rework structure

bare-metal-bsp/drivers/clic/clic_driver.c

@@ -0,0 +1,163 @@
+// See LICENSE for license details.
+
+#include "sifive/devices/clic.h"
+#include "clic/clic_driver.h"
+#include "platform.h"
+#include "encoding.h"
+#include <string.h>
+
+
+void volatile_memzero(uint8_t * base, unsigned int size) {
+  volatile uint8_t * ptr;
+  for (ptr = base; ptr < (base + size); ptr++){
+    *ptr = 0;
+  }
+}
+
+// Note that there are no assertions or bounds checking on these
+// parameter values.
+void clic_init (
+                clic_instance_t * this_clic,
+                uintptr_t hart_addr,
+                interrupt_function_ptr_t* vect_table,
+                interrupt_function_ptr_t default_handler,
+                uint32_t num_irq,
+                uint32_t num_config_bits
+                )
+{
+  this_clic->hart_addr=  hart_addr;
+  this_clic->vect_table= vect_table;
+  this_clic->num_config_bits= num_config_bits;
+
+  //initialize vector table
+  for(int i=0;i++;i<num_irq)  {
+    this_clic->vect_table[i] = default_handler;
+  }
+
+  //set base vectors
+  write_csr(mtvt, vect_table);
+
+
+  //clear all interrupt enables and pending
+  volatile_memzero((uint8_t*)(this_clic->hart_addr+CLIC_INTIE), num_irq);
+  volatile_memzero((uint8_t*)(this_clic->hart_addr+CLIC_INTIP), num_irq);
+
+  //clear nlbits and nvbits; all interrupts trap to level 15
+  *(volatile uint8_t*)(this_clic->hart_addr+CLIC_CFG)=0;
+
+}
+
+void clic_install_handler (clic_instance_t * this_clic, uint32_t source, interrupt_function_ptr_t handler) {
+    this_clic->vect_table[source] = handler;
+}
+
+void clic_enable_interrupt (clic_instance_t * this_clic, uint32_t source) {
+    *(volatile uint8_t*)(this_clic->hart_addr+CLIC_INTIE+source) = 1;
+}
+
+void clic_disable_interrupt (clic_instance_t * this_clic, uint32_t source){
+  *(volatile uint8_t*)(this_clic->hart_addr+CLIC_INTIE+source) = 0;
+}
+
+void clic_set_pending(clic_instance_t * this_clic, uint32_t source){
+  *(volatile uint8_t*)(this_clic->hart_addr+CLIC_INTIP+source) = 1;
+}
+
+void clic_clear_pending(clic_instance_t * this_clic, uint32_t source){
+  *(volatile uint8_t*)(this_clic->hart_addr+CLIC_INTIP+source) = 0;
+}
+
+void clic_set_intcfg (clic_instance_t * this_clic, uint32_t source, uint32_t intcfg){
+  *(volatile uint8_t*)(this_clic->hart_addr+CLIC_INTCFG+source) = intcfg;
+}
+
+uint8_t clic_get_intcfg  (clic_instance_t * this_clic, uint32_t source){
+  return *(volatile uint8_t*)(this_clic->hart_addr+CLIC_INTCFG+source);
+}
+
+void clic_set_cliccfg (clic_instance_t * this_clic, uint32_t cfg){
+  *(volatile uint8_t*)(this_clic->hart_addr+CLIC_CFG) = cfg;
+}
+
+uint8_t clic_get_cliccfg  (clic_instance_t * this_clic){
+  return *(volatile uint8_t*)(this_clic->hart_addr+CLIC_CFG);
+}
+
+//sets an interrupt level based encoding of nmbits, nlbits
+uint8_t clic_set_int_level( clic_instance_t * this_clic, uint32_t source, uint8_t level) {
+  //extract nlbits
+  uint8_t nlbits = clic_get_cliccfg(this_clic);
+  nlbits = (nlbits >>1) & 0x7;
+
+  //shift level right to mask off unused bits
+  level = level>>((this_clic->num_config_bits)-nlbits); //plus this_clic->nmbits which is always 0 for now.
+  //shift level into correct bit position
+  level = level << (8-this_clic->num_config_bits) + (this_clic->num_config_bits - nlbits);
+ 
+  //write to clicintcfg
+  uint8_t current_intcfg = clic_get_intcfg(this_clic, source);
+  clic_set_intcfg(this_clic, source, (current_intcfg | level));
+
+  return level;
+}
+
+//gets an interrupt level based encoding of nmbits, nlbits
+uint8_t clic_get_int_level( clic_instance_t * this_clic, uint32_t source) {
+  uint8_t level;
+  level = clic_get_intcfg(this_clic, source);
+
+  //extract nlbits
+  uint8_t nlbits = clic_get_cliccfg(this_clic);
+  nlbits = (nlbits >>1) & 0x7;
+
+  //shift level
+  level = level >> (8-(this_clic->num_config_bits));
+
+  //shift level right to mask off priority bits
+  level = level>>(this_clic->num_config_bits-nlbits); //this_clic->nmbits which is always 0 for now.
+
+  return level;
+}
+
+//sets an interrupt priority based encoding of nmbits, nlbits
+uint8_t clic_set_int_priority( clic_instance_t * this_clic, uint32_t source, uint8_t priority) {
+  //priority bits = num_config_bits - nlbits
+  //extract nlbits
+  uint8_t nlbits = clic_get_cliccfg(this_clic);
+  nlbits = (nlbits >>1) & 0x7;
+
+  uint8_t priority_bits = this_clic->num_config_bits-nlbits;
+  if(priority_bits = 0) {
+    //no bits to set
+    return 0;
+  }
+  //mask off unused bits
+  priority = priority >> (8-priority_bits);
+  //shift into the correct bit position
+  priority = priority << (8-(this_clic->num_config_bits));
+
+  //write to clicintcfg
+  uint8_t current_intcfg = clic_get_intcfg(this_clic, source);
+  clic_set_intcfg(this_clic, source, (current_intcfg | priority));
+  return current_intcfg;
+}
+
+//gets an interrupt priority based encoding of nmbits, nlbits
+uint8_t clic_get_int_priority( clic_instance_t * this_clic, uint32_t source) {
+  uint8_t priority;
+  priority = clic_get_intcfg(this_clic, source);
+
+  //extract nlbits
+  uint8_t nlbits = clic_get_cliccfg(this_clic);
+  nlbits = (nlbits >>1) & 0x7;
+
+  //shift left to mask off level bits
+  priority = priority << nlbits;
+
+  //shift priority
+  priority = priority >> (8-((this_clic->num_config_bits)+nlbits));
+
+ return priority;
+}
+
+

bare-metal-bsp/drivers/clic/clic_driver.h

@@ -0,0 +1,44 @@
+// See LICENSE file for licence details
+
+#ifndef PLIC_DRIVER_H
+#define PLIC_DRIVER_H
+
+
+__BEGIN_DECLS
+
+#include "platform.h"
+
+typedef void (*interrupt_function_ptr_t) (void);
+
+typedef struct __clic_instance_t
+{
+  uintptr_t hart_addr;
+  interrupt_function_ptr_t* vect_table;
+  uint32_t num_config_bits;
+  uint32_t num_sources;  
+} clic_instance_t;
+
+// Note that there are no assertions or bounds checking on these
+// parameter values.
+void clic_init (clic_instance_t * this_clic, uintptr_t hart_addr, interrupt_function_ptr_t* vect_table, interrupt_function_ptr_t default_handler, uint32_t num_irq,uint32_t num_config_bits);
+void clic_install_handler (clic_instance_t * this_clic, uint32_t source, interrupt_function_ptr_t handler);
+void clic_enable_interrupt (clic_instance_t * this_clic, uint32_t source);
+void clic_disable_interrupt (clic_instance_t * this_clic, uint32_t source);
+void clic_set_pending(clic_instance_t * this_clic, uint32_t source);
+void clic_clear_pending(clic_instance_t * this_clic, uint32_t source);
+void clic_set_intcfg (clic_instance_t * this_clic, uint32_t source, uint32_t intcfg);
+uint8_t clic_get_intcfg (clic_instance_t * this_clic, uint32_t source);
+void clic_set_cliccfg (clic_instance_t * this_clic, uint32_t cfg);
+uint8_t clic_get_cliccfg  (clic_instance_t * this_clic);
+//sets an interrupt level based encoding of nmbits, nlbits
+uint8_t clic_set_int_level( clic_instance_t * this_clic, uint32_t source, uint8_t level);
+//get an interrupt level based encoding of nmbits, nlbits
+uint8_t clic_get_int_level( clic_instance_t * this_clic, uint32_t source);
+//sets an interrupt priority based encoding of nmbits, nlbits
+uint8_t clic_set_int_priority( clic_instance_t * this_clic, uint32_t source, uint8_t priority);
+//sets an interrupt priority based encoding of nmbits, nlbits
+uint8_t clic_get_int_priority( clic_instance_t * this_clic, uint32_t source);
+
+__END_DECLS
+
+#endif

bare-metal-bsp/drivers/fe300prci/fe300prci_driver.c

@@ -0,0 +1,252 @@
+// See LICENSE file for license details
+
+#include "platform.h"
+
+#ifdef PRCI_BASE_ADDR
+#include "fe300prci/fe300prci_driver.h"
+#include <unistd.h>
+
+#define rdmcycle(x)  {				       \
+    uint32_t lo, hi, hi2;			       \
+    __asm__ __volatile__ ("1:\n\t"		       \
+			  "csrr %0, mcycleh\n\t"       \
+			  "csrr %1, mcycle\n\t"	       \
+			  "csrr %2, mcycleh\n\t"		\
+			  "bne  %0, %2, 1b\n\t"			\
+			  : "=r" (hi), "=r" (lo), "=r" (hi2)) ;	\
+    *(x) = lo | ((uint64_t) hi << 32); 				\
+  }
+
+uint32_t PRCI_measure_mcycle_freq(uint32_t mtime_ticks, uint32_t mtime_freq)
+{
+
+  uint32_t start_mtime = CLINT_REG(CLINT_MTIME);
+  uint32_t end_mtime = start_mtime + mtime_ticks + 1;
+
+  // Make sure we won't get rollover.
+  while (end_mtime < start_mtime){
+    start_mtime = CLINT_REG(CLINT_MTIME);
+    end_mtime = start_mtime + mtime_ticks + 1;
+  }
+
+  // Don't start measuring until mtime edge.
+  uint32_t tmp = start_mtime;
+  do {
+    start_mtime = CLINT_REG(CLINT_MTIME);
+  } while (start_mtime == tmp);
+  
+  uint64_t start_mcycle;
+  rdmcycle(&start_mcycle);
+  
+  while (CLINT_REG(CLINT_MTIME) < end_mtime) ;
+  
+  uint64_t end_mcycle;
+  rdmcycle(&end_mcycle);
+  uint32_t difference = (uint32_t) (end_mcycle - start_mcycle);
+
+  uint64_t freq = ((uint64_t) difference * mtime_freq) / mtime_ticks;
+  return (uint32_t) freq & 0xFFFFFFFF;
+  
+}
+ 
+
+void PRCI_use_hfrosc(int div, int trim)
+{
+  // Make sure the HFROSC is running at its default setting
+  // It is OK to change this even if we are running off of it.
+  
+  PRCI_REG(PRCI_HFROSCCFG) = (ROSC_DIV(div) | ROSC_TRIM(trim) | ROSC_EN(1));
+
+  while ((PRCI_REG(PRCI_HFROSCCFG) & ROSC_RDY(1)) == 0);
+  
+  PRCI_REG(PRCI_PLLCFG) &= ~PLL_SEL(1);
+}
+
+void PRCI_use_pll(int refsel, int bypass,
+			 int r, int f, int q, int finaldiv,
+			 int hfroscdiv, int hfrosctrim)
+{
+  // Ensure that we aren't running off the PLL before we mess with it.
+  if (PRCI_REG(PRCI_PLLCFG) & PLL_SEL(1)) {
+    // Make sure the HFROSC is running at its default setting
+    PRCI_use_hfrosc(4, 16);
+  }
+  
+  // Set PLL Source to be HFXOSC if desired.
+  uint32_t config_value = 0;
+
+  config_value |= PLL_REFSEL(refsel);
+  
+  if (bypass) {
+    // Bypass
+    config_value |= PLL_BYPASS(1);
+
+    PRCI_REG(PRCI_PLLCFG) = config_value;
+
+    // If we don't have an HFXTAL, this doesn't really matter.
+    // Set our Final output divide to divide-by-1:
+    PRCI_REG(PRCI_PLLDIV) = (PLL_FINAL_DIV_BY_1(1) | PLL_FINAL_DIV(0));
+  } else {
+  
+    // To overclock, use the hfrosc
+    if (hfrosctrim >= 0 && hfroscdiv >= 0) {
+      PRCI_use_hfrosc(hfroscdiv, hfrosctrim);
+    }
+    
+    // Set DIV Settings for PLL
+    
+    // (Legal values of f_REF are 6-48MHz)
+
+    // Set DIVR to divide-by-2 to get 8MHz frequency
+    // (legal values of f_R are 6-12 MHz)
+
+    config_value |= PLL_BYPASS(1);
+    config_value |= PLL_R(r);
+
+    // Set DIVF to get 512Mhz frequncy
+    // There is an implied multiply-by-2, 16Mhz.
+    // So need to write 32-1
+    // (legal values of f_F are 384-768 MHz)
+    config_value |= PLL_F(f);
+
+    // Set DIVQ to divide-by-2 to get 256 MHz frequency
+    // (legal values of f_Q are 50-400Mhz)
+    config_value |= PLL_Q(q);
+
+    // Set our Final output divide to divide-by-1:
+    if (finaldiv == 1){
+      PRCI_REG(PRCI_PLLDIV) = (PLL_FINAL_DIV_BY_1(1) | PLL_FINAL_DIV(0));
+    } else {
+      PRCI_REG(PRCI_PLLDIV) = (PLL_FINAL_DIV(finaldiv-1));
+    }
+
+    PRCI_REG(PRCI_PLLCFG) = config_value;
+
+    // Un-Bypass the PLL.
+    PRCI_REG(PRCI_PLLCFG) &= ~PLL_BYPASS(1);
+
+    // Wait for PLL Lock
+    // Note that the Lock signal can be glitchy.
+    // Need to wait 100 us
+    // RTC is running at 32kHz.
+    // So wait 4 ticks of RTC.
+    uint32_t now = CLINT_REG(CLINT_MTIME);
+    while (CLINT_REG(CLINT_MTIME) - now < 4) ;
+    
+    // Now it is safe to check for PLL Lock
+    while ((PRCI_REG(PRCI_PLLCFG) & PLL_LOCK(1)) == 0);
+
+  }
+
+  // Switch over to PLL Clock source
+  PRCI_REG(PRCI_PLLCFG) |= PLL_SEL(1);
+
+  // If we're running off HFXOSC, turn off the HFROSC to
+  // save power.
+  if (refsel) {
+    PRCI_REG(PRCI_HFROSCCFG) &= ~ROSC_EN(1);
+  }
+  
+}
+
+void PRCI_use_default_clocks()
+{
+  // Turn off the LFROSC
+  AON_REG(AON_LFROSC) &= ~ROSC_EN(1);
+
+  // Use HFROSC
+  PRCI_use_hfrosc(4, 16);
+}
+
+void PRCI_use_hfxosc(uint32_t finaldiv)
+{
+  
+  PRCI_use_pll(1, // Use HFXTAL
+	       1, // Bypass = 1
+	       0, // PLL settings don't matter
+	       0, // PLL settings don't matter
+	       0, // PLL settings don't matter
+	       finaldiv,
+	       -1,
+	       -1);
+}
+
+// This is a generic function, which
+// doesn't span the entire range of HFROSC settings.
+// It only adjusts the trim, which can span a hundred MHz or so.
+// This function does not check the legality of the PLL settings
+// at all, and it is quite possible to configure invalid PLL settings
+// this way.
+// It returns the actual measured CPU frequency.
+
+uint32_t PRCI_set_hfrosctrim_for_f_cpu(uint32_t f_cpu, PRCI_freq_target target )
+{
+
+  uint32_t hfrosctrim = 0;
+  uint32_t hfroscdiv = 4;
+  uint32_t prev_trim = 0;
+
+  // In this function we use PLL settings which
+  // will give us a 32x multiplier from the output
+  // of the HFROSC source to the output of the
+  // PLL. We first measure our HFROSC to get the
+  // right trim, then finally use it as the PLL source.
+  // We should really check here that the f_cpu
+  // requested is something in the limit of the PLL. For
+  // now that is up to the user.
+
+  // This will undershoot for frequencies not divisible by 16.
+  uint32_t desired_hfrosc_freq = (f_cpu/ 16);
+
+  PRCI_use_hfrosc(hfroscdiv, hfrosctrim);
+  
+  // Ignore the first run (for icache reasons)
+  uint32_t cpu_freq = PRCI_measure_mcycle_freq(3000, RTC_FREQ);
+
+  cpu_freq = PRCI_measure_mcycle_freq(3000, RTC_FREQ);
+  uint32_t prev_freq = cpu_freq;
+  
+  while ((cpu_freq < desired_hfrosc_freq) && (hfrosctrim < 0x1F)){
+    prev_trim = hfrosctrim;
+    prev_freq = cpu_freq;
+    hfrosctrim ++;
+    PRCI_use_hfrosc(hfroscdiv, hfrosctrim);
+    cpu_freq = PRCI_measure_mcycle_freq(3000, RTC_FREQ);
+  } 
+
+  // We couldn't go low enough
+  if (prev_freq > desired_hfrosc_freq){
+    PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, prev_trim);
+    cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ);
+    return cpu_freq;
+  }
+  
+  // We couldn't go high enough
+  if (cpu_freq < desired_hfrosc_freq){
+    PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, prev_trim);
+    cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ);
+    return cpu_freq;
+  }
+
+  // Check for over/undershoot
+  switch(target) {
+  case(PRCI_FREQ_CLOSEST):
+    if ((desired_hfrosc_freq - prev_freq) < (cpu_freq - desired_hfrosc_freq)) {
+      PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, prev_trim);
+    } else {
+      PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, hfrosctrim);
+    }
+    break;
+  case(PRCI_FREQ_UNDERSHOOT):
+    PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, prev_trim);
+    break;
+  default:
+    PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, hfrosctrim);
+  }
+
+  cpu_freq =  PRCI_measure_mcycle_freq(1000, RTC_FREQ);
+  return cpu_freq;
+
+}
+
+#endif

bare-metal-bsp/drivers/fe300prci/fe300prci_driver.h

@@ -0,0 +1,79 @@
+// See LICENSE file for license details
+
+#ifndef _FE300PRCI_DRIVER_H_
+#define _FE300PRCI_DRIVER_H_
+
+__BEGIN_DECLS
+
+#include <unistd.h>
+
+typedef enum prci_freq_target {
+  
+  PRCI_FREQ_OVERSHOOT,
+  PRCI_FREQ_CLOSEST,
+  PRCI_FREQ_UNDERSHOOT
+
+} PRCI_freq_target;
+
+/* Measure and return the approximate frequency of the 
+ * CPU, as given by measuring the mcycle counter against 
+ * the mtime ticks.
+ */
+uint32_t PRCI_measure_mcycle_freq(uint32_t mtime_ticks, uint32_t mtime_freq);
+
+/* Safely switch over to the HFROSC using the given div
+ * and trim settings.
+ */
+void PRCI_use_hfrosc(int div, int trim);
+
+/* Safely switch over to the 16MHz HFXOSC,
+ * applying the finaldiv clock divider (1 is the lowest
+ * legal value).
+ */
+void PRCI_use_hfxosc(uint32_t finaldiv);
+
+/* Safely switch over to the PLL using the given
+ * settings.
+ * 
+ * Note that not all combinations of the inputs are actually
+ * legal, and this function does not check for their
+ * legality ("safely" means that this function won't turn off
+ * or glitch the clock the CPU is actually running off, but
+ * doesn't protect against you making it too fast or slow.)
+ */
+
+void PRCI_use_pll(int refsel, int bypass,
+			 int r, int f, int q, int finaldiv,
+			 int hfroscdiv, int hfrosctrim);
+
+/* Use the default clocks configured at reset.
+ * This is ~16Mhz HFROSC and turns off the LFROSC
+ * (on the current FE310 Dev Platforms, an external LFROSC is 
+ * used as it is more power efficient).
+ */
+void PRCI_use_default_clocks();
+
+/* This routine will adjust the HFROSC trim
+ * while using HFROSC as the clock source, 
+ * measure the resulting frequency, then
+ * use it as the PLL clock source, 
+ * in an attempt to get over, under, or close to the 
+ * requested frequency. It returns the actual measured 
+ * frequency. 
+ *
+ * Note that the requested frequency must be within the 
+ * range supported by the PLL so not all values are 
+ * achievable with this function, and not all 
+ * are guaranteed to actually work. The PLL
+ * is rated higher than the hardware.
+ * 
+ * There is no check on the desired f_cpu frequency, it
+ * is up to the user to specify something reasonable.
+ */
+
+uint32_t PRCI_set_hfrosctrim_for_f_cpu(uint32_t f_cpu, PRCI_freq_target target);
+
+__END_DECLS
+
+#endif
+  

bare-metal-bsp/drivers/plic/plic_driver.c

@@ -0,0 +1,127 @@
+// See LICENSE for license details.
+
+#include "sifive/devices/plic.h"
+#include "plic/plic_driver.h"
+#include "platform.h"
+#include "encoding.h"
+#include <string.h>
+
+
+// Note that there are no assertions or bounds checking on these
+// parameter values.
+
+void volatile_memzero(uint8_t * base, unsigned int size)
+{
+  volatile uint8_t * ptr;
+  for (ptr = base; ptr < (base + size); ptr++){
+    *ptr = 0;
+  }
+}
+
+void PLIC_init (
+                plic_instance_t * this_plic,
+                uintptr_t         base_addr,
+                uint32_t num_sources,
+                uint32_t num_priorities
+                )
+{
+  
+  this_plic->base_addr = base_addr;
+  this_plic->num_sources = num_sources;
+  this_plic->num_priorities = num_priorities;
+  
+  // Disable all interrupts (don't assume that these registers are reset).
+  unsigned long hart_id = read_csr(mhartid);
+  volatile_memzero((uint8_t*) (this_plic->base_addr +
+                               PLIC_ENABLE_OFFSET +
+                               (hart_id << PLIC_ENABLE_SHIFT_PER_TARGET)),
+                   (num_sources + 8) / 8);
+  
+  // Set all priorities to 0 (equal priority -- don't assume that these are reset).
+  volatile_memzero ((uint8_t *)(this_plic->base_addr +
+                                PLIC_PRIORITY_OFFSET),
+                    (num_sources + 1) << PLIC_PRIORITY_SHIFT_PER_SOURCE);
+
+  // Set the threshold to 0.
+  volatile plic_threshold* threshold = (plic_threshold*)
+    (this_plic->base_addr +
+     PLIC_THRESHOLD_OFFSET +
+     (hart_id << PLIC_THRESHOLD_SHIFT_PER_TARGET));
+
+  *threshold = 0;
+  
+}
+
+void PLIC_set_threshold (plic_instance_t * this_plic,
+			 plic_threshold threshold){
+
+  unsigned long hart_id = read_csr(mhartid);  
+  volatile plic_threshold* threshold_ptr = (plic_threshold*) (this_plic->base_addr +
+                                                              PLIC_THRESHOLD_OFFSET +
+                                                              (hart_id << PLIC_THRESHOLD_SHIFT_PER_TARGET));
+
+  *threshold_ptr = threshold;
+
+}
+  
+
+void PLIC_enable_interrupt (plic_instance_t * this_plic, plic_source source){
+
+  unsigned long hart_id = read_csr(mhartid);
+  volatile uint8_t * current_ptr = (volatile uint8_t *)(this_plic->base_addr +
+                                                        PLIC_ENABLE_OFFSET +
+                                                        (hart_id << PLIC_ENABLE_SHIFT_PER_TARGET) +
+                                                        (source >> 3));
+  uint8_t current = *current_ptr;
+  current = current | ( 1 << (source & 0x7));
+  *current_ptr = current;
+
+}
+
+void PLIC_disable_interrupt (plic_instance_t * this_plic, plic_source source){
+  
+  unsigned long hart_id = read_csr(mhartid);
+  volatile uint8_t * current_ptr = (volatile uint8_t *) (this_plic->base_addr +
+                                                         PLIC_ENABLE_OFFSET +
+                                                         (hart_id << PLIC_ENABLE_SHIFT_PER_TARGET) +
+                                                         (source >> 3));
+  uint8_t current = *current_ptr;
+  current = current & ~(( 1 << (source & 0x7)));
+  *current_ptr = current;
+  
+}
+
+void PLIC_set_priority (plic_instance_t * this_plic, plic_source source, plic_priority priority){
+
+  if (this_plic->num_priorities > 0) {
+    volatile plic_priority * priority_ptr = (volatile plic_priority *)
+      (this_plic->base_addr +
+       PLIC_PRIORITY_OFFSET +
+       (source << PLIC_PRIORITY_SHIFT_PER_SOURCE));
+    *priority_ptr = priority;
+  }
+}
+
+plic_source PLIC_claim_interrupt(plic_instance_t * this_plic){
+  
+  unsigned long hart_id = read_csr(mhartid);
+
+  volatile plic_source * claim_addr = (volatile plic_source * )
+    (this_plic->base_addr +
+     PLIC_CLAIM_OFFSET +
+     (hart_id << PLIC_CLAIM_SHIFT_PER_TARGET));
+
+  return  *claim_addr;
+  
+}
+
+void PLIC_complete_interrupt(plic_instance_t * this_plic, plic_source source){
+  
+  unsigned long hart_id = read_csr(mhartid);
+  volatile plic_source * claim_addr = (volatile plic_source *) (this_plic->base_addr +
+                                                                PLIC_CLAIM_OFFSET +
+                                                                (hart_id << PLIC_CLAIM_SHIFT_PER_TARGET));
+  *claim_addr = source;
+  
+}
+

bare-metal-bsp/drivers/plic/plic_driver.h

@@ -0,0 +1,51 @@
+// See LICENSE file for licence details
+
+#ifndef PLIC_DRIVER_H
+#define PLIC_DRIVER_H
+
+
+__BEGIN_DECLS
+
+#include "platform.h"
+
+typedef struct __plic_instance_t
+{
+  uintptr_t base_addr;
+
+  uint32_t num_sources;
+  uint32_t num_priorities;
+  
+} plic_instance_t;
+
+typedef uint32_t plic_source;
+typedef uint32_t plic_priority;
+typedef uint32_t plic_threshold;
+
+void PLIC_init (
+                plic_instance_t * this_plic,
+                uintptr_t         base_addr,
+                uint32_t num_sources,
+                uint32_t num_priorities
+                );
+
+void PLIC_set_threshold (plic_instance_t * this_plic,
+			 plic_threshold threshold);
+  
+void PLIC_enable_interrupt (plic_instance_t * this_plic,
+			    plic_source source);
+
+void PLIC_disable_interrupt (plic_instance_t * this_plic,
+			     plic_source source);
+  
+void PLIC_set_priority (plic_instance_t * this_plic,
+			plic_source source,
+			plic_priority priority);
+
+plic_source PLIC_claim_interrupt(plic_instance_t * this_plic);
+
+void PLIC_complete_interrupt(plic_instance_t * this_plic,
+			     plic_source source);
+
+__END_DECLS
+
+#endif

bare-metal-bsp/env/.gitignore

@@ -0,0 +1 @@
+/*.o

bare-metal-bsp/env/common-clang.mk

@@ -0,0 +1,72 @@
+# See LICENSE for license details.
+
+ifndef _SIFIVE_MK_COMMON
+_SIFIVE_MK_COMMON := # defined
+
+.PHONY: all
+all: $(TARGET)
+
+include $(BSP_BASE)/libwrap/libwrap.mk
+
+ENV_DIR = $(BSP_BASE)/env
+PLATFORM_DIR = $(ENV_DIR)/$(BOARD)
+
+ASM_SRCS += $(ENV_DIR)/start.S
+ASM_SRCS += $(ENV_DIR)/entry.S
+C_SRCS += $(PLATFORM_DIR)/init.c
+
+LINKER_SCRIPT := $(PLATFORM_DIR)/$(LINK_TARGET).lds
+
+INCLUDES += -I$(BSP_BASE)/include
+INCLUDES += -I$(BSP_BASE)/drivers/
+INCLUDES += -I$(ENV_DIR)
+INCLUDES += -I$(PLATFORM_DIR)
+
+TOOL_DIR ?= $(BSP_BASE)/../toolchain/bin/
+
+LDFLAGS += -T $(LINKER_SCRIPT) -nostartfiles
+LDFLAGS += -L$(ENV_DIR) --specs=nano.specs
+
+ASM_OBJS := $(ASM_SRCS:.S=.o)
+C_OBJS   := $(C_SRCS:.c=.o)
+CXX_OBJS := $(CXX_SRCS:.cpp=.o)
+
+LINK_OBJS += $(ASM_OBJS) $(C_OBJS) $(CXX_OBJS)
+LINK_DEPS += $(LINKER_SCRIPT)
+
+CLEAN_OBJS += $(TARGET) $(LINK_OBJS)
+
+CFLAGS += -march=$(RISCV_ARCH)
+CFLAGS += -mabi=$(RISCV_ABI)
+CFLAGS += -mcmodel=medany
+
+TRIPLET?=riscv32
+CXX=$(LLVM_TOOL_DIR)clang++ --target=$(TRIPLET) -isystem $(TOOL_DIR)/../$(TRIPLET)/include
+CC=$(LLVM_TOOL_DIR)clang --target=$(TRIPLET) -isystem $(TOOL_DIR)/../$(TRIPLET)/include
+LD=$(TOOL_DIR)$(TRIPLET)-gcc
+AR=$(TOOL_DIR)$(TRIPLET)-ar
+OBJDUMP := $(TOOL_DIR)/$(TRIPLET)-objdump
+
+
+$(TARGET): $(LINK_OBJS) $(LINK_DEPS)
+	$(LD) $(LINK_OBJS) $(LDFLAGS) $(LIBWRAP) -o $@
+	$(OBJDUMP) -d -S $(TARGET) > $(TARGET).dis
+	
+$(ASM_OBJS): %.o: %.S $(HEADERS)
+	$(CC) $(CFLAGS) $(INCLUDES) -c -o $@ $<
+
+$(C_OBJS): %.o: %.c $(HEADERS)
+	$(CC) $(CFLAGS) $(INCLUDES) -include sys/cdefs.h -c -o $@ $<
+
+$(CXX_OBJS): %.o: %.cpp $(HEADERS)
+	$(CXX) $(CFLAGS) $(CXXFLAGS) $(INCLUDES) -include sys/cdefs.h -c -o $@ $<
+
+.PHONY: clean
+clean:
+	rm -f $(TARGET) $(LINK_OBJS)
+
+.PHONY: clean-all
+clean-all:
+	rm -f $(CLEAN_OBJS) $(LIBWRAP)
+
+endif

bare-metal-bsp/env/common-gcc.mk

@@ -0,0 +1,74 @@
+ifndef _MK_COMMON
+_MK_COMMON := # defined
+
+.PHONY: all
+all: $(TARGET)
+
+include $(BSP_BASE)/libwrap/libwrap.mk
+
+BOARD?=iss
+ENV_DIR = $(BSP_BASE)/env
+PLATFORM_DIR = $(ENV_DIR)/$(BOARD)
+
+ASM_SRCS += $(ENV_DIR)/start.S
+ASM_SRCS += $(ENV_DIR)/entry.S
+C_SRCS += $(PLATFORM_DIR)/init.c
+
+LINKER_SCRIPT := $(PLATFORM_DIR)/$(LINK_TARGET).lds
+
+INCLUDES += -I$(BSP_BASE)/include
+INCLUDES += -I$(BSP_BASE)/drivers/
+INCLUDES += -I$(ENV_DIR)
+INCLUDES += -I$(PLATFORM_DIR)
+
+TOOL_DIR ?= $(BSP_BASE)/../toolchain/bin/
+
+LDFLAGS += -march=$(RISCV_ARCH) -mabi=$(RISCV_ABI)
+LDFLAGS += -T $(LINKER_SCRIPT) -Wl,-Map=$(TARGET).map  -nostartfiles
+LDFLAGS += -L$(ENV_DIR)
+# --specs=nano.specs
+
+ASM_OBJS := $(ASM_SRCS:.S=.o)
+C_OBJS   := $(C_SRCS:.c=.o)
+CXX_OBJS := $(CXX_SRCS:.cpp=.o)
+
+LINK_OBJS += $(ASM_OBJS) $(C_OBJS) $(CXX_OBJS)
+LINK_DEPS += $(LINKER_SCRIPT)
+
+CLEAN_OBJS += $(TARGET) $(LINK_OBJS)
+
+GCCVERSION = $(shell $(CC) --version | grep gcc | awk '{print($NF);}')
+ifeq ($(GCCVERSION),9.2)
+  CFLAGS += -march=$(RISCV_ARCH)
+else
+  CFLAGS += -march=$(RISCV_ARCH)_zicsr_zifencei
+endif
+CFLAGS += -mabi=$(RISCV_ABI)
+CFLAGS += -mcmodel=medany
+
+TRIPLET?=riscv64-unknown-elf
+CXX=$(TOOL_DIR)$(TRIPLET)-c++
+CC=$(TOOL_DIR)$(TRIPLET)-gcc
+LD=$(TOOL_DIR)$(TRIPLET)-gcc
+AR=$(TOOL_DIR)$(TRIPLET)-ar
+OBJDUMP := $(TOOL_DIR)$(TRIPLET)-objdump
+
+
+$(TARGET): $(LINK_OBJS) $(LINK_DEPS)
+	$(LD) $(LINK_OBJS) $(LDFLAGS) $(LIBWRAP) -o $@
+	$(OBJDUMP) -d -S $(TARGET) > $(TARGET).dis
+	
+$(ASM_OBJS): %.o: %.S $(HEADERS)
+	$(CC) $(CFLAGS) $(INCLUDES) -c -o $@ $<
+
+$(C_OBJS): %.o: %.c $(HEADERS)
+	$(CC) $(CFLAGS) $(INCLUDES) -include sys/cdefs.h -c -o $@ $<
+
+$(CXX_OBJS): %.o: %.cpp $(HEADERS)
+	$(CXX) $(CFLAGS) $(CXXFLAGS) $(INCLUDES) -include sys/cdefs.h -c -o $@ $<
+
+.PHONY: clean
+clean:
+	rm -f $(CLEAN_OBJS) $(LIBWRAP)
+
+endif

bare-metal-bsp/env/entry.S

@@ -0,0 +1,99 @@
+// See LICENSE for license details
+
+#ifndef ENTRY_S
+#define ENTRY_S
+
+#include "encoding.h"
+#include "rtl/bits.h"
+
+  .section      .text.entry	
+  .align 2
+  .global trap_entry
+trap_entry:
+  addi sp, sp, -32*REGBYTES
+
+  STORE x1, 1*REGBYTES(sp)
+  STORE x2, 2*REGBYTES(sp)
+  STORE x3, 3*REGBYTES(sp)
+  STORE x4, 4*REGBYTES(sp)
+  STORE x5, 5*REGBYTES(sp)
+  STORE x6, 6*REGBYTES(sp)
+  STORE x7, 7*REGBYTES(sp)
+  STORE x8, 8*REGBYTES(sp)
+  STORE x9, 9*REGBYTES(sp)
+  STORE x10, 10*REGBYTES(sp)
+  STORE x11, 11*REGBYTES(sp)
+  STORE x12, 12*REGBYTES(sp)
+  STORE x13, 13*REGBYTES(sp)
+  STORE x14, 14*REGBYTES(sp)
+  STORE x15, 15*REGBYTES(sp)
+#ifndef __riscv_abi_rve
+  STORE x16, 16*REGBYTES(sp)
+  STORE x17, 17*REGBYTES(sp)
+  STORE x18, 18*REGBYTES(sp)
+  STORE x19, 19*REGBYTES(sp)
+  STORE x20, 20*REGBYTES(sp)
+  STORE x21, 21*REGBYTES(sp)
+  STORE x22, 22*REGBYTES(sp)
+  STORE x23, 23*REGBYTES(sp)
+  STORE x24, 24*REGBYTES(sp)
+  STORE x25, 25*REGBYTES(sp)
+  STORE x26, 26*REGBYTES(sp)
+  STORE x27, 27*REGBYTES(sp)
+  STORE x28, 28*REGBYTES(sp)
+  STORE x29, 29*REGBYTES(sp)
+  STORE x30, 30*REGBYTES(sp)
+  STORE x31, 31*REGBYTES(sp)
+#endif
+  csrr a0, mcause
+  csrr a1, mepc
+  mv a2, sp
+  call handle_trap
+  csrw mepc, a0
+
+  # Remain in M-mode after mret
+  li t0, MSTATUS_MPP
+  csrs mstatus, t0
+
+  LOAD x1, 1*REGBYTES(sp)
+  LOAD x2, 2*REGBYTES(sp)
+  LOAD x3, 3*REGBYTES(sp)
+  LOAD x4, 4*REGBYTES(sp)
+  LOAD x5, 5*REGBYTES(sp)
+  LOAD x6, 6*REGBYTES(sp)
+  LOAD x7, 7*REGBYTES(sp)
+  LOAD x8, 8*REGBYTES(sp)
+  LOAD x9, 9*REGBYTES(sp)
+  LOAD x10, 10*REGBYTES(sp)
+  LOAD x11, 11*REGBYTES(sp)
+  LOAD x12, 12*REGBYTES(sp)
+  LOAD x13, 13*REGBYTES(sp)
+  LOAD x14, 14*REGBYTES(sp)
+  LOAD x15, 15*REGBYTES(sp)
+#ifndef __riscv_abi_rve
+  LOAD x16, 16*REGBYTES(sp)
+  LOAD x17, 17*REGBYTES(sp)
+  LOAD x18, 18*REGBYTES(sp)
+  LOAD x19, 19*REGBYTES(sp)
+  LOAD x20, 20*REGBYTES(sp)
+  LOAD x21, 21*REGBYTES(sp)
+  LOAD x22, 22*REGBYTES(sp)
+  LOAD x23, 23*REGBYTES(sp)
+  LOAD x24, 24*REGBYTES(sp)
+  LOAD x25, 25*REGBYTES(sp)
+  LOAD x26, 26*REGBYTES(sp)
+  LOAD x27, 27*REGBYTES(sp)
+  LOAD x28, 28*REGBYTES(sp)
+  LOAD x29, 29*REGBYTES(sp)
+  LOAD x30, 30*REGBYTES(sp)
+  LOAD x31, 31*REGBYTES(sp)
+#endif
+  addi sp, sp, 32*REGBYTES
+  mret
+
+.weak handle_trap
+handle_trap:
+1:
+  j 1b
+	
+#endif

bare-metal-bsp/env/iss/.gitignore

@@ -0,0 +1 @@
+/*.o

bare-metal-bsp/env/iss/init.c

@@ -0,0 +1,107 @@
+#include <stdint.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include "platform.h"
+#include "encoding.h"
+
+extern int main(int argc, char** argv);
+extern void trap_entry();
+
+static unsigned long mtime_lo(void)
+{
+    unsigned long ret;
+    __asm volatile("rdtime %0":"=r"(ret));
+    return ret;
+}
+
+
+#if __riscv_xlen==32
+
+static uint32_t mtime_hi(void)
+{
+    unsigned long ret;
+    __asm volatile("rdtimeh %0":"=r"(ret));
+    return ret;
+}
+
+uint64_t get_timer_value()
+{
+  while (1) {
+    uint32_t hi = mtime_hi();
+    uint32_t lo = mtime_lo();
+    if (hi == mtime_hi())
+      return ((uint64_t)hi << 32) | lo;
+  }
+}
+
+#elif __riscv_xlen==64
+
+uint64_t get_timer_value()
+{
+  return mtime_lo();
+}
+
+#endif
+
+unsigned long get_timer_freq()
+{
+  return 32768;
+}
+
+unsigned long get_cpu_freq()
+{
+  return 10000000;
+}
+
+void init_pll(void){
+
+}
+
+#ifdef USE_PLIC
+extern void handle_m_ext_interrupt();
+#endif
+
+#ifdef USE_M_TIME
+extern void handle_m_time_interrupt();
+#endif
+
+uintptr_t handle_trap(uintptr_t mcause, uintptr_t epc)
+{
+  if (0){
+#ifdef USE_PLIC
+    // External Machine-Level interrupt from PLIC
+  } else if ((mcause & MCAUSE_INT) && ((mcause & MCAUSE_CAUSE) == IRQ_M_EXT)) {
+    handle_m_ext_interrupt();
+#endif
+#ifdef USE_M_TIME
+    // External Machine-Level interrupt from PLIC
+  } else if ((mcause & MCAUSE_INT) && ((mcause & MCAUSE_CAUSE) == IRQ_M_TIMER)){
+    handle_m_time_interrupt();
+#endif
+  }
+  else {
+    write(1, "trap\n", 5);
+    _exit(1 + mcause);
+  }
+  return epc;
+}
+
+void _init()
+{
+  
+#ifndef NO_INIT
+  init_pll();
+  printf("core freq at %d Hz\n", get_cpu_freq());
+  write_csr(mtvec, &trap_entry);
+  if (read_csr(misa) & (1 << ('F' - 'A'))) { // if F extension is present
+    write_csr(mstatus, MSTATUS_FS); // allow FPU instructions without trapping
+    write_csr(fcsr, 0); // initialize rounding mode, undefined at reset
+  }
+#endif
+  
+}
+
+void _fini()
+{
+}

bare-metal-bsp/env/iss/link.lds

@@ -0,0 +1,174 @@
+OUTPUT_ARCH( "riscv" )
+
+ENTRY( _start )
+
+MEMORY
+{
+  flash (rxai!w) : ORIGIN = 0x00000020, LENGTH = 1M
+  ram (wxa!ri) :   ORIGIN = 0x10000000, LENGTH = 16K
+}
+
+PHDRS
+{
+  flash PT_LOAD;
+  ram_init PT_LOAD;
+  ram PT_NULL;
+}
+
+SECTIONS
+{
+  __stack_size = DEFINED(__stack_size) ? __stack_size : 2K;
+
+  .init ORIGIN(flash)        :
+  {
+    KEEP (*(SORT_NONE(.init)))
+  } >flash AT>flash :flash
+
+  .text           :
+  {
+    *(.text.unlikely .text.unlikely.*)
+    *(.text.startup .text.startup.*)
+    *(.text .text.*)
+    *(.gnu.linkonce.t.*)
+  } >flash AT>flash :flash
+
+  .fini           :
+  {
+    KEEP (*(SORT_NONE(.fini)))
+  } >flash AT>flash :flash
+
+  PROVIDE (__etext = .);
+  PROVIDE (_etext = .);
+  PROVIDE (etext = .);
+
+  .rodata         :
+  {
+    *(.rdata)
+    *(.rodata .rodata.*)
+    *(.gnu.linkonce.r.*)
+  } >flash AT>flash :flash
+
+  . = ALIGN(4);
+
+  .preinit_array  :
+  {
+    PROVIDE_HIDDEN (__preinit_array_start = .);
+    KEEP (*(.preinit_array))
+    PROVIDE_HIDDEN (__preinit_array_end = .);
+  } >flash AT>flash :flash
+
+  .init_array     :
+  {
+    PROVIDE_HIDDEN (__init_array_start = .);
+    KEEP (*(SORT_BY_INIT_PRIORITY(.init_array.*) SORT_BY_INIT_PRIORITY(.ctors.*)))
+    KEEP (*(.init_array EXCLUDE_FILE (*crtbegin.o *crtbegin?.o *crtend.o *crtend?.o ) .ctors))
+    PROVIDE_HIDDEN (__init_array_end = .);
+  } >flash AT>flash :flash
+
+  .fini_array     :
+  {
+    PROVIDE_HIDDEN (__fini_array_start = .);
+    KEEP (*(SORT_BY_INIT_PRIORITY(.fini_array.*) SORT_BY_INIT_PRIORITY(.dtors.*)))
+    KEEP (*(.fini_array EXCLUDE_FILE (*crtbegin.o *crtbegin?.o *crtend.o *crtend?.o ) .dtors))
+    PROVIDE_HIDDEN (__fini_array_end = .);
+  } >flash AT>flash :flash
+
+  .ctors          :
+  {
+    /* gcc uses crtbegin.o to find the start of
+       the constructors, so we make sure it is
+       first.  Because this is a wildcard, it
+       doesn't matter if the user does not
+       actually link against crtbegin.o; the
+       linker won't look for a file to match a
+       wildcard.  The wildcard also means that it
+       doesn't matter which directory crtbegin.o
+       is in.  */
+    KEEP (*crtbegin.o(.ctors))
+    KEEP (*crtbegin?.o(.ctors))
+    /* We don't want to include the .ctor section from
+       the crtend.o file until after the sorted ctors.
+       The .ctor section from the crtend file contains the
+       end of ctors marker and it must be last */
+    KEEP (*(EXCLUDE_FILE (*crtend.o *crtend?.o ) .ctors))
+    KEEP (*(SORT(.ctors.*)))
+    KEEP (*(.ctors))
+  } >flash AT>flash :flash
+
+  .dtors          :
+  {
+    KEEP (*crtbegin.o(.dtors))
+    KEEP (*crtbegin?.o(.dtors))
+    KEEP (*(EXCLUDE_FILE (*crtend.o *crtend?.o ) .dtors))
+    KEEP (*(SORT(.dtors.*)))
+    KEEP (*(.dtors))
+  } >flash AT>flash :flash
+
+  .lalign         :
+  {
+    . = ALIGN(4);
+    PROVIDE( _data_lma = . );
+  } >flash AT>flash :flash
+
+  .dalign         :
+  {
+    . = ALIGN(4);
+    PROVIDE( _data = . );
+  } >ram AT>flash :ram_init
+
+  .data          :
+  {
+    __DATA_BEGIN__ = .;
+    *(.data .data.*)
+    *(.gnu.linkonce.d.*)
+  } >ram AT>flash :ram_init
+
+  .srodata        :
+  {
+    PROVIDE( _gp = . + 0x800 );
+    *(.srodata.cst16)
+    *(.srodata.cst8)
+    *(.srodata.cst4)
+    *(.srodata.cst2)
+    *(.srodata .srodata.*)
+  } >ram AT>flash :ram_init
+
+  .sdata          :
+  {
+    __SDATA_BEGIN__ = .;
+    *(.sdata .sdata.*)
+    *(.gnu.linkonce.s.*)
+  } >ram AT>flash :ram_init
+
+  . = ALIGN(4);
+  PROVIDE( _edata = . );
+  PROVIDE( edata = . );
+
+  PROVIDE( _fbss = . );
+  PROVIDE( __bss_start = . );
+  .bss            :
+  {
+    *(.sbss*)
+    *(.gnu.linkonce.sb.*)
+    *(.bss .bss.*)
+    *(.gnu.linkonce.b.*)
+    *(COMMON)
+    . = ALIGN(4);
+  } >ram AT>ram :ram
+
+  . = ALIGN(8);
+  __BSS_END__ = .;
+  __global_pointer$ = MIN(__SDATA_BEGIN__ + 0x800,  MAX(__DATA_BEGIN__ + 0x800, __BSS_END__ - 0x800));
+  PROVIDE( _end = . );
+  PROVIDE( end = . );
+
+  .stack ORIGIN(ram) + LENGTH(ram) - __stack_size :
+  {
+    PROVIDE( _heap_end = . );
+    . = __stack_size;
+    PROVIDE( _sp = . );
+  } >ram AT>ram :ram
+
+  PROVIDE( tohost = 0xfffffff0 );
+  PROVIDE( fromhost = 0xfffffff8 );
+}

bare-metal-bsp/env/iss/platform.h

@@ -0,0 +1,30 @@
+// See LICENSE for license details.
+
+#ifndef _ISS_PLATFORM_H
+#define _ISS_PLATFORM_H
+
+// Some things missing from the official encoding.h
+#define MCAUSE_INT         0x80000000
+#define MCAUSE_CAUSE       0x7FFFFFFF
+
+#include "rtl/const.h"
+/****************************************************************************
+ * Platform definitions
+ *****************************************************************************/
+
+#define MEM_BASE_ADDR _AC(0x00000000,UL)
+
+// Helper functions
+#define _REG32(p, i) (*(volatile uint32_t *) ((p) + (i)))
+#define _REG32P(p, i) ((volatile uint32_t *) ((p) + (i)))
+
+// Misc
+
+#include <stdint.h>
+
+void init_pll(void);
+unsigned long get_cpu_freq(void);
+unsigned long get_timer_freq(void);
+uint64_t get_timer_value(void);
+
+#endif /* _ISS_PLATFORM_H */

bare-metal-bsp/env/rtl/.gitignore

@@ -0,0 +1 @@
+/*.o

bare-metal-bsp/env/rtl/init.c

@@ -0,0 +1,107 @@
+#include <stdint.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include "platform.h"
+#include "encoding.h"
+
+extern int main(int argc, char** argv);
+extern void trap_entry();
+
+static unsigned long mtime_lo(void)
+{
+    unsigned long ret;
+    __asm volatile("rdtime %0":"=r"(ret));
+    return ret;
+}
+
+
+#if __riscv_xlen==32
+
+static uint32_t mtime_hi(void)
+{
+    unsigned long ret;
+    __asm volatile("rdtimeh %0":"=r"(ret));
+    return ret;
+}
+
+uint64_t get_timer_value()
+{
+  while (1) {
+    uint32_t hi = mtime_hi();
+    uint32_t lo = mtime_lo();
+    if (hi == mtime_hi())
+      return ((uint64_t)hi << 32) | lo;
+  }
+}
+
+#elif __riscv_xlen==64
+
+uint64_t get_timer_value()
+{
+  return mtime_lo();
+}
+
+#endif
+
+unsigned long get_timer_freq()
+{
+  return 32768;
+}
+
+unsigned long get_cpu_freq()
+{
+  return 10000000;
+}
+
+void init_pll(void){
+
+}
+
+#ifdef USE_PLIC
+extern void handle_m_ext_interrupt();
+#endif
+
+#ifdef USE_M_TIME
+extern void handle_m_time_interrupt();
+#endif
+
+uintptr_t handle_trap(uintptr_t mcause, uintptr_t epc)
+{
+  if (0){
+#ifdef USE_PLIC
+    // External Machine-Level interrupt from PLIC
+  } else if ((mcause & MCAUSE_INT) && ((mcause & MCAUSE_CAUSE) == IRQ_M_EXT)) {
+    handle_m_ext_interrupt();
+#endif
+#ifdef USE_M_TIME
+    // External Machine-Level interrupt from PLIC
+  } else if ((mcause & MCAUSE_INT) && ((mcause & MCAUSE_CAUSE) == IRQ_M_TIMER)){
+    handle_m_time_interrupt();
+#endif
+  }
+  else {
+    write(1, "trap\n", 5);
+    _exit(1 + mcause);
+  }
+  return epc;
+}
+
+void _init()
+{
+  
+#ifndef NO_INIT
+  init_pll();
+  printf("core freq at %d Hz\n", get_cpu_freq());
+  write_csr(mtvec, &trap_entry);
+  if (read_csr(misa) & (1 << ('F' - 'A'))) { // if F extension is present
+    write_csr(mstatus, MSTATUS_FS); // allow FPU instructions without trapping
+    write_csr(fcsr, 0); // initialize rounding mode, undefined at reset
+  }
+#endif
+  
+}
+
+void _fini()
+{
+}

bare-metal-bsp/env/rtl/link.lds

@@ -0,0 +1,170 @@
+OUTPUT_ARCH( "riscv" )
+
+ENTRY( _start )
+
+MEMORY
+{
+  flash (rxai!w) : ORIGIN = 0x00000000, LENGTH = 1M
+  ram (wxa!ri) :   ORIGIN = 0x10000000, LENGTH = 16K
+}
+
+PHDRS
+{
+  flash PT_LOAD;
+  ram_init PT_LOAD;
+  ram PT_NULL;
+}
+
+SECTIONS
+{
+  __stack_size = DEFINED(__stack_size) ? __stack_size : 2K;
+
+  .init ORIGIN(flash)        :
+  {
+    KEEP (*(SORT_NONE(.init)))
+  } >flash AT>flash :flash
+
+  .text           :
+  {
+    *(.text.unlikely .text.unlikely.*)
+    *(.text.startup .text.startup.*)
+    *(.text .text.*)
+    *(.gnu.linkonce.t.*)
+  } >flash AT>flash :flash
+
+  .fini           :
+  {
+    KEEP (*(SORT_NONE(.fini)))
+  } >flash AT>flash :flash
+
+  PROVIDE (__etext = .);
+  PROVIDE (_etext = .);
+  PROVIDE (etext = .);
+
+  .rodata         :
+  {
+    *(.rdata)
+    *(.rodata .rodata.*)
+    *(.gnu.linkonce.r.*)
+  } >flash AT>flash :flash
+
+  . = ALIGN(4);
+
+  .preinit_array  :
+  {
+    PROVIDE_HIDDEN (__preinit_array_start = .);
+    KEEP (*(.preinit_array))
+    PROVIDE_HIDDEN (__preinit_array_end = .);
+  } >flash AT>flash :flash
+
+  .init_array     :
+  {
+    PROVIDE_HIDDEN (__init_array_start = .);
+    KEEP (*(SORT_BY_INIT_PRIORITY(.init_array.*) SORT_BY_INIT_PRIORITY(.ctors.*)))
+    KEEP (*(.init_array EXCLUDE_FILE (*crtbegin.o *crtbegin?.o *crtend.o *crtend?.o ) .ctors))
+    PROVIDE_HIDDEN (__init_array_end = .);
+  } >flash AT>flash :flash
+
+  .fini_array     :
+  {
+    PROVIDE_HIDDEN (__fini_array_start = .);
+    KEEP (*(SORT_BY_INIT_PRIORITY(.fini_array.*) SORT_BY_INIT_PRIORITY(.dtors.*)))
+    KEEP (*(.fini_array EXCLUDE_FILE (*crtbegin.o *crtbegin?.o *crtend.o *crtend?.o ) .dtors))
+    PROVIDE_HIDDEN (__fini_array_end = .);
+  } >flash AT>flash :flash
+
+  .ctors          :
+  {
+    /* gcc uses crtbegin.o to find the start of
+       the constructors, so we make sure it is
+       first.  Because this is a wildcard, it
+       doesn't matter if the user does not
+       actually link against crtbegin.o; the
+       linker won't look for a file to match a
+       wildcard.  The wildcard also means that it
+       doesn't matter which directory crtbegin.o
+       is in.  */
+    KEEP (*crtbegin.o(.ctors))
+    KEEP (*crtbegin?.o(.ctors))
+    /* We don't want to include the .ctor section from
+       the crtend.o file until after the sorted ctors.
+       The .ctor section from the crtend file contains the
+       end of ctors marker and it must be last */
+    KEEP (*(EXCLUDE_FILE (*crtend.o *crtend?.o ) .ctors))
+    KEEP (*(SORT(.ctors.*)))
+    KEEP (*(.ctors))
+  } >flash AT>flash :flash
+
+  .dtors          :
+  {
+    KEEP (*crtbegin.o(.dtors))
+    KEEP (*crtbegin?.o(.dtors))
+    KEEP (*(EXCLUDE_FILE (*crtend.o *crtend?.o ) .dtors))
+    KEEP (*(SORT(.dtors.*)))
+    KEEP (*(.dtors))
+  } >flash AT>flash :flash
+
+  .lalign         :
+  {
+    . = ALIGN(4);
+    PROVIDE( _data_lma = . );
+  } >flash AT>flash :flash
+
+  .dalign         :
+  {
+    . = ALIGN(4);
+    PROVIDE( _data = . );
+  } >ram AT>flash :ram_init
+
+  .data          :
+  {
+    *(.data .data.*)
+    *(.gnu.linkonce.d.*)
+  } >ram AT>flash :ram_init
+
+  .srodata        :
+  {
+    PROVIDE( _gp = . + 0x800 );
+    *(.srodata.cst16)
+    *(.srodata.cst8)
+    *(.srodata.cst4)
+    *(.srodata.cst2)
+    *(.srodata .srodata.*)
+  } >ram AT>flash :ram_init
+
+  .sdata          :
+  {
+    *(.sdata .sdata.*)
+    *(.gnu.linkonce.s.*)
+  } >ram AT>flash :ram_init
+
+  . = ALIGN(4);
+  PROVIDE( _edata = . );
+  PROVIDE( edata = . );
+
+  PROVIDE( _fbss = . );
+  PROVIDE( __bss_start = . );
+  .bss            :
+  {
+    *(.sbss*)
+    *(.gnu.linkonce.sb.*)
+    *(.bss .bss.*)
+    *(.gnu.linkonce.b.*)
+    *(COMMON)
+    . = ALIGN(4);
+  } >ram AT>ram :ram
+
+  . = ALIGN(8);
+  PROVIDE( _end = . );
+  PROVIDE( end = . );
+
+  .stack ORIGIN(ram) + LENGTH(ram) - __stack_size :
+  {
+    PROVIDE( _heap_end = . );
+    . = __stack_size;
+    PROVIDE( _sp = . );
+  } >ram AT>ram :ram
+
+  PROVIDE( tohost = 0x00018000 );
+  PROVIDE( fromhost = 0xfffffff8 );
+}

bare-metal-bsp/env/rtl/platform.h

@@ -0,0 +1,30 @@
+// See LICENSE for license details.
+
+#ifndef _ISS_PLATFORM_H
+#define _ISS_PLATFORM_H
+
+// Some things missing from the official encoding.h
+#define MCAUSE_INT         0x80000000
+#define MCAUSE_CAUSE       0x7FFFFFFF
+
+#include "rtl/const.h"
+/****************************************************************************
+ * Platform definitions
+ *****************************************************************************/
+
+#define MEM_BASE_ADDR _AC(0x00000000,UL)
+
+// Helper functions
+#define _REG32(p, i) (*(volatile uint32_t *) ((p) + (i)))
+#define _REG32P(p, i) ((volatile uint32_t *) ((p) + (i)))
+
+// Misc
+
+#include <stdint.h>
+
+void init_pll(void);
+unsigned long get_cpu_freq(void);
+unsigned long get_timer_freq(void);
+uint64_t get_timer_value(void);
+
+#endif /* _ISS_PLATFORM_H */

bare-metal-bsp/env/start.S

@@ -0,0 +1,58 @@
+// See LICENSE for license details.
+
+	.section .init
+	.globl _start
+	.type _start,@function
+
+_start:
+.option push
+.option norelax
+    la gp, __global_pointer$
+.option pop
+	la sp, _sp
+
+	/* Load data section */
+	la a0, _data_lma
+	la a1, _data
+	la a2, _edata
+	bgeu a1, a2, 2f
+1:
+	lw t0, (a0)
+	sw t0, (a1)
+	addi a0, a0, 4
+	addi a1, a1, 4
+	bltu a1, a2, 1b
+2:
+
+	/* Clear bss section */
+	la a0, __bss_start
+	la a1, _end
+	bgeu a0, a1, 2f
+1:
+	sw zero, (a0)
+	addi a0, a0, 4
+	bltu a0, a1, 1b
+2:
+
+	/* Call global constructors */
+#ifdef HAVE_INIT_FINI
+	la a0, __libc_fini_array
+	call atexit
+	call __libc_init_array
+#endif
+#ifndef __riscv_float_abi_soft
+	/* Enable FPU */
+	li t0, MSTATUS_FS
+	csrs mstatus, t0
+	csrr t1, mstatus
+	and t1, t1, t0
+	beqz t1, 1f
+	fssr x0
+1:
+#endif
+
+	/* argc = argv = 0 */
+	li a0, 0
+	li a1, 0
+	call main
+	tail _exit

bare-metal-bsp/include/rtl/bits.h

@@ -0,0 +1,35 @@
+#ifndef _RISCV_BITS_H
+#define _RISCV_BITS_H
+
+#define likely(x) __builtin_expect((x), 1)
+#define unlikely(x) __builtin_expect((x), 0)
+
+#define ROUNDUP(a, b) ((((a)-1)/(b)+1)*(b))
+#define ROUNDDOWN(a, b) ((a)/(b)*(b))
+
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+#define CLAMP(a, lo, hi) MIN(MAX(a, lo), hi)
+
+#define EXTRACT_FIELD(val, which) (((val) & (which)) / ((which) & ~((which)-1)))
+#define INSERT_FIELD(val, which, fieldval) (((val) & ~(which)) | ((fieldval) * ((which) & ~((which)-1))))
+
+#define STR(x) XSTR(x)
+#define XSTR(x) #x
+
+#ifdef __riscv64
+# define SLL32    sllw
+# define STORE    sd
+# define LOAD     ld
+# define LWU      lwu
+# define LOG_REGBYTES 3
+#else
+# define SLL32    sll
+# define STORE    sw
+# define LOAD     lw
+# define LWU      lw
+# define LOG_REGBYTES 2
+#endif
+#define REGBYTES (1 << LOG_REGBYTES)
+
+#endif

bare-metal-bsp/include/rtl/const.h

@@ -0,0 +1,27 @@
+#ifndef _RTL_CONST_H
+#define _RTL_CONST_H
+
+#ifdef __ASSEMBLER__
+#define _AC(X,Y)        X
+#define _AT(T,X)        X
+#else
+#define _AC(X,Y)        (X##Y)
+#define _AT(T,X)        ((T)(X))
+#endif /* !__ASSEMBLER__*/
+
+#define _BITUL(x)       (_AC(1,UL) << (x))
+#define _BITULL(x)      (_AC(1,ULL) << (x))
+
+#define UART0_BASE_ADDR 0xffff0000ULL
+
+#define UART_REG_TXFIFO         0x00
+#define UART_REG_RXFIFO         0x04
+#define UART_REG_TXCTRL         0x08
+#define UART_REG_RXCTRL         0x0c
+#define UART_REG_IE             0x10
+#define UART_REG_IP             0x14
+#define UART_REG_DIV            0x18
+#define UART_TXEN               0x1
+
+#define UART0_REG(ADDR) *((volatile uint32_t*) (UART0_BASE_ADDR + ADDR))
+#endif /* _RTL_CONST_H */

bare-metal-bsp/include/rtl/sections.h

@@ -0,0 +1,16 @@
+#ifndef _SECTIONS_H
+#define _SECTIONS_H
+
+extern unsigned char _rom[];
+extern unsigned char _rom_end[];
+
+extern unsigned char _ram[];
+extern unsigned char _ram_end[];
+
+extern unsigned char _ftext[];
+extern unsigned char _etext[];
+extern unsigned char _fbss[];
+extern unsigned char _ebss[];
+extern unsigned char _end[];
+
+#endif /* _SECTIONS_H */

bare-metal-bsp/libwrap/libwrap.mk

@@ -0,0 +1,53 @@
+ifndef _MK_LIBWRAP
+_MK_LIBWRAP := # defined
+
+LIBWRAP_DIR := $(dir $(lastword $(MAKEFILE_LIST)))
+LIBWRAP_DIR := $(LIBWRAP_DIR:/=)
+
+LIBWRAP_SRCS := \
+	stdlib/malloc.c \
+	sys/open.c \
+	sys/lseek.c \
+	sys/read.c \
+	sys/write.c \
+	sys/fstat.c \
+	sys/stat.c \
+	sys/close.c \
+	sys/link.c \
+	sys/unlink.c \
+	sys/execve.c \
+	sys/fork.c \
+	sys/getpid.c \
+	sys/kill.c \
+	sys/wait.c \
+	sys/isatty.c \
+	sys/times.c \
+	sys/sbrk.c \
+	sys/_exit.c \
+	misc/write_hex.c \
+	sys/printf.c
+
+LIBWRAP_SRCS := $(foreach f,$(LIBWRAP_SRCS),$(LIBWRAP_DIR)/$(f))
+LIBWRAP_OBJS := $(LIBWRAP_SRCS:.c=.o)
+
+LIBWRAP_SYMS := malloc free \
+	open lseek read write fstat stat close link unlink \
+	execve fork getpid kill wait \
+	isatty times sbrk _exit
+
+LIBWRAP := libwrap.a
+
+LINK_DEPS += $(LIBWRAP)
+
+LDFLAGS += $(foreach s,$(LIBWRAP_SYMS),-Wl,--wrap=$(s))
+LDFLAGS += -L. -Wl,--start-group -lwrap -lc -Wl,--end-group
+
+CLEAN_OBJS += $(LIBWRAP_OBJS)
+
+$(LIBWRAP_OBJS): %.o: %.c $(HEADERS)
+	$(CC) $(CFLAGS) $(INCLUDES) -c -o $@ $<
+
+$(LIBWRAP): $(LIBWRAP_OBJS)
+	$(AR) rcs $@ $^
+
+endif # _MK_LIBWRAP

bare-metal-bsp/libwrap/misc/.gitignore

@@ -0,0 +1 @@
+/*.o

bare-metal-bsp/libwrap/misc/write_hex.c

@@ -0,0 +1,19 @@
+/* See LICENSE of license details. */
+
+#include <stdint.h>
+#include <unistd.h>
+#include "platform.h"
+
+void write_hex(int fd, uint32_t hex)
+{
+  uint8_t ii;
+  uint8_t jj;
+  char towrite;
+  write(fd , "0x", 2);
+  for (ii = 8 ; ii > 0; ii--) {
+    jj = ii - 1;
+    uint8_t digit = ((hex & (0xF << (jj*4))) >> (jj*4));
+    towrite = digit < 0xA ? ('0' + digit) : ('A' +  (digit - 0xA));
+    write(fd, &towrite, 1);
+  }
+}

bare-metal-bsp/libwrap/stdlib/.gitignore

@@ -0,0 +1 @@
+/*.o

bare-metal-bsp/libwrap/stdlib/malloc.c

@@ -0,0 +1,17 @@
+/* See LICENSE for license details. */
+
+/* These functions are intended for embedded RV32 systems and are
+   obviously incorrect in general. */
+
+void* __wrap_malloc(unsigned long sz)
+{
+  extern void* sbrk(long);
+  void* res = sbrk(sz);
+  if ((long)res == -1)
+    return 0;
+  return res;
+}
+
+void __wrap_free(void* ptr)
+{
+}

bare-metal-bsp/libwrap/sys/.gitignore

@@ -0,0 +1 @@
+/*.o

bare-metal-bsp/libwrap/sys/_exit.c

@@ -0,0 +1,21 @@
+/* See LICENSE of license details. */
+
+#include <unistd.h>
+#include "platform.h"
+
+extern volatile uint32_t tohost;
+extern volatile uint32_t fromhost;
+
+void __wrap__exit(int code)
+{
+//volatile uint32_t* leds = (uint32_t*) (GPIO_BASE_ADDR + GPIO_OUT_OFFSET);
+  const char message[] = "\nProgam has exited with code:";
+//*leds = (~(code));
+
+  write(STDERR_FILENO, message, sizeof(message) - 1);
+  write_hex(STDERR_FILENO, code);
+  write(STDERR_FILENO, "\n", 1);
+  tohost = code+1;
+  write(STDERR_FILENO, "\x04", 1);
+  for (;;);
+}

bare-metal-bsp/libwrap/sys/close.c

@@ -0,0 +1,9 @@
+/* See LICENSE of license details. */
+
+#include <errno.h>
+#include "stub.h"
+
+int __wrap_close(int fd)
+{
+  return _stub(EBADF);
+}

bare-metal-bsp/libwrap/sys/execve.c

@@ -0,0 +1,9 @@
+/* See LICENSE of license details. */
+
+#include <errno.h>
+#include "stub.h"
+
+int __wrap_execve(const char* name, char* const argv[], char* const env[])
+{
+  return _stub(ENOMEM);
+}

bare-metal-bsp/libwrap/sys/fork.c

@@ -0,0 +1,9 @@
+/* See LICENSE of license details. */
+
+#include <errno.h>
+#include "stub.h"
+
+int fork(void)
+{
+  return _stub(EAGAIN);
+}

bare-metal-bsp/libwrap/sys/fstat.c

@@ -0,0 +1,16 @@
+/* See LICENSE of license details. */
+
+#include <errno.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include "stub.h"
+
+int __wrap_fstat(int fd, struct stat* st)
+{
+  if (isatty(fd)) {
+    st->st_mode = S_IFCHR;
+    return 0;
+  }
+
+  return _stub(EBADF);
+}

bare-metal-bsp/libwrap/sys/getpid.c

@@ -0,0 +1,6 @@
+/* See LICENSE of license details. */
+
+int __wrap_getpid(void)
+{
+  return 1;
+}

bare-metal-bsp/libwrap/sys/isatty.c

@@ -0,0 +1,11 @@
+/* See LICENSE of license details. */
+
+#include <unistd.h>
+
+int __wrap_isatty(int fd)
+{
+  if (fd == STDOUT_FILENO || fd == STDERR_FILENO)
+    return 1;
+
+  return 0;
+}

bare-metal-bsp/libwrap/sys/kill.c

@@ -0,0 +1,9 @@
+/* See LICENSE of license details. */
+
+#include <errno.h>
+#include "stub.h"
+
+int __wrap_kill(int pid, int sig)
+{
+  return _stub(EINVAL);
+}

bare-metal-bsp/libwrap/sys/link.c

@@ -0,0 +1,9 @@
+/* See LICENSE of license details. */
+
+#include <errno.h>
+#include "stub.h"
+
+int __wrap_link(const char *old_name, const char *new_name)
+{
+  return _stub(EMLINK);
+}

bare-metal-bsp/libwrap/sys/lseek.c

@@ -0,0 +1,14 @@
+/* See LICENSE of license details. */
+
+#include <errno.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include "stub.h"
+
+off_t __wrap_lseek(int fd, off_t ptr, int dir)
+{
+  if (isatty(fd))
+    return 0;
+
+  return _stub(EBADF);
+}

bare-metal-bsp/libwrap/sys/open.c

@@ -0,0 +1,9 @@
+/* See LICENSE of license details. */
+
+#include <errno.h>
+#include "stub.h"
+
+int __wrap_open(const char* name, int flags, int mode)
+{
+  return _stub(ENOENT);
+}

bare-metal-bsp/libwrap/sys/openat.c

@@ -0,0 +1,9 @@
+/* See LICENSE of license details. */
+
+#include <errno.h>
+#include "stub.h"
+
+int __wrap_openat(int dirfd, const char* name, int flags, int mode)
+{
+  return _stub(ENOENT);
+}

bare-metal-bsp/libwrap/sys/printf.c

@@ -0,0 +1,278 @@
+/* The functions in this file are only meant to support Dhrystone on an
+ * embedded RV32 system and are obviously incorrect in general. */
+
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <unistd.h>
+
+#undef putchar
+int putchar(int ch)
+{
+  return write(STDOUT_FILENO, &ch, 1) == 1 ? ch : -1;
+}
+
+size_t strnlen (const char *str, size_t n)
+{
+  const char *start = str;
+  while (n-- > 0 && *str) str++;
+  return str - start;
+}
+
+static void sprintf_putch(int ch, void** data)
+{
+  char** pstr = (char**)data;
+  **pstr = ch;
+  (*pstr)++;
+}
+
+static unsigned long getuint(va_list *ap, int lflag)
+{
+  if (lflag)
+    return va_arg(*ap, unsigned long);
+  else
+    return va_arg(*ap, unsigned int);
+}
+
+static long getint(va_list *ap, int lflag)
+{
+  if (lflag)
+    return va_arg(*ap, long);
+  else
+    return va_arg(*ap, int);
+}
+
+static inline void printnum(void (*putch)(int, void**), void **putdat,
+                    unsigned long num, unsigned base, int width, int padc)
+{
+  unsigned digs[sizeof(num)*8];
+  int pos = 0;
+
+  while (1)
+  {
+    digs[pos++] = num % base;
+    if (num < base)
+      break;
+    num /= base;
+  }
+
+  while (width-- > pos)
+    putch(padc, putdat);
+
+  while (pos-- > 0)
+    putch(digs[pos] + (digs[pos] >= 10 ? 'a' - 10 : '0'), putdat);
+}
+
+static inline void print_double(void (*putch)(int, void**), void **putdat,
+                                double num, int width, int prec)
+{
+  union {
+    double d;
+    uint64_t u;
+  } u;
+  u.d = num;
+
+  if (u.u & (1ULL << 63)) {
+    putch('-', putdat);
+    u.u &= ~(1ULL << 63);
+  }
+
+  for (int i = 0; i < prec; i++)
+    u.d *= 10;
+
+  char buf[32], *pbuf = buf;
+  printnum(sprintf_putch, (void**)&pbuf, (unsigned long)u.d, 10, 0, 0);
+  if (prec > 0) {
+    for (int i = 0; i < prec; i++) {
+      pbuf[-i] = pbuf[-i-1];
+    }
+    pbuf[-prec] = '.';
+    pbuf++;
+  }
+
+  for (char* p = buf; p < pbuf; p++)
+    putch(*p, putdat);
+}
+
+static void vprintfmt(void (*putch)(int, void**), void **putdat, const char *fmt, va_list ap)
+{
+  register const char* p;
+  const char* last_fmt;
+  register int ch, err;
+  unsigned long num;
+  int base, lflag, width, precision, altflag;
+  char padc;
+
+  while (1) {
+    while ((ch = *(unsigned char *) fmt) != '%') {
+      if (ch == '\0')
+        return;
+      fmt++;
+      putch(ch, putdat);
+    }
+    fmt++;
+
+    // Process a %-escape sequence
+    last_fmt = fmt;
+    padc = ' ';
+    width = -1;
+    precision = -1;
+    lflag = 0;
+    altflag = 0;
+  reswitch:
+    switch (ch = *(unsigned char *) fmt++) {
+
+    // flag to pad on the right
+    case '-':
+      padc = '-';
+      goto reswitch;
+      
+    // flag to pad with 0's instead of spaces
+    case '0':
+      padc = '0';
+      goto reswitch;
+
+    // width field
+    case '1':
+    case '2':
+    case '3':
+    case '4':
+    case '5':
+    case '6':
+    case '7':
+    case '8':
+    case '9':
+      for (precision = 0; ; ++fmt) {
+        precision = precision * 10 + ch - '0';
+        ch = *fmt;
+        if (ch < '0' || ch > '9')
+          break;
+      }
+      goto process_precision;
+
+    case '*':
+      precision = va_arg(ap, int);
+      goto process_precision;
+
+    case '.':
+      if (width < 0)
+        width = 0;
+      goto reswitch;
+
+    case '#':
+      altflag = 1;
+      goto reswitch;
+
+    process_precision:
+      if (width < 0)
+        width = precision, precision = -1;
+      goto reswitch;
+
+    // long flag
+    case 'l':
+      if (lflag)
+        goto bad;
+      goto reswitch;
+
+    // character
+    case 'c':
+      putch(va_arg(ap, int), putdat);
+      break;
+
+    // double
+    case 'f':
+      print_double(putch, putdat, va_arg(ap, double), width, precision);
+      break;
+
+    // string
+    case 's':
+      if ((p = va_arg(ap, char *)) == NULL)
+        p = "(null)";
+      if (width > 0 && padc != '-')
+        for (width -= strnlen(p, precision); width > 0; width--)
+          putch(padc, putdat);
+      for (; (ch = *p) != '\0' && (precision < 0 || --precision >= 0); width--) {
+        putch(ch, putdat);
+        p++;
+      }
+      for (; width > 0; width--)
+        putch(' ', putdat);
+      break;
+
+    // (signed) decimal
+    case 'd':
+      num = getint(&ap, lflag);
+      if ((long) num < 0) {
+        putch('-', putdat);
+        num = -(long) num;
+      }
+      base = 10;
+      goto signed_number;
+
+    // unsigned decimal
+    case 'u':
+      base = 10;
+      goto unsigned_number;
+
+    // (unsigned) octal
+    case 'o':
+      // should do something with padding so it's always 3 octits
+      base = 8;
+      goto unsigned_number;
+
+    // pointer
+    case 'p':
+      lflag = 1;
+      putch('0', putdat);
+      putch('x', putdat);
+      /* fall through to 'x' */
+
+    // (unsigned) hexadecimal
+    case 'x':
+      base = 16;
+    unsigned_number:
+      num = getuint(&ap, lflag);
+    signed_number:
+      printnum(putch, putdat, num, base, width, padc);
+      break;
+
+    // escaped '%' character
+    case '%':
+      putch(ch, putdat);
+      break;
+      
+    // unrecognized escape sequence - just print it literally
+    default:
+    bad:
+      putch('%', putdat);
+      fmt = last_fmt;
+      break;
+    }
+  }
+}
+
+int __wrap_printf(const char* fmt, ...)
+{
+  va_list ap;
+  va_start(ap, fmt);
+
+  vprintfmt((void*)putchar, 0, fmt, ap);
+
+  va_end(ap);
+  return 0; // incorrect return value, but who cares, anyway?
+}
+
+int __wrap_sprintf(char* str, const char* fmt, ...)
+{
+  va_list ap;
+  char* str0 = str;
+  va_start(ap, fmt);
+
+  vprintfmt(sprintf_putch, (void**)&str, fmt, ap);
+  *str = 0;
+
+  va_end(ap);
+  return str - str0;
+}

bare-metal-bsp/libwrap/sys/read.c

@@ -0,0 +1,30 @@
+/* See LICENSE of license details. */
+
+#include <stdint.h>
+#include <errno.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+#include "platform.h"
+#include "stub.h"
+
+ssize_t __wrap_read(int fd, void* ptr, size_t len)
+{
+  uint8_t * current = (uint8_t *)ptr;
+  volatile uint32_t * uart_rx = (uint32_t *)(UART0_BASE_ADDR + UART_REG_RXFIFO);
+  volatile uint8_t * uart_rx_cnt = (uint8_t *)(UART0_BASE_ADDR + UART_REG_RXCTRL + 2);
+
+  ssize_t result = 0;
+
+  if (isatty(fd)) {
+    for (current = (uint8_t *)ptr;
+        (current < ((uint8_t *)ptr) + len) && (*uart_rx_cnt > 0);
+        current ++) {
+      *current = *uart_rx;
+      result++;
+    }
+    return result;
+  }
+
+  return _stub(EBADF);
+}

bare-metal-bsp/libwrap/sys/sbrk.c

@@ -0,0 +1,16 @@
+/* See LICENSE of license details. */
+
+#include <stddef.h>
+
+void *__wrap_sbrk(ptrdiff_t incr)
+{
+  extern char _end[];
+  extern char _heap_end[];
+  static char *curbrk = _end;
+
+  if ((curbrk + incr < _end) || (curbrk + incr > _heap_end))
+    return NULL - 1;
+
+  curbrk += incr;
+  return curbrk - incr;
+}

bare-metal-bsp/libwrap/sys/stat.c

@@ -0,0 +1,10 @@
+/* See LICENSE of license details. */
+
+#include <errno.h>
+#include <sys/stat.h>
+#include "stub.h"
+
+int __wrap_stat(const char* file, struct stat* st)
+{
+  return _stub(EACCES);
+}

bare-metal-bsp/libwrap/sys/stub.h

@@ -0,0 +1,10 @@
+/* See LICENSE of license details. */
+#ifndef _SIFIVE_SYS_STUB_H
+#define _SIFIVE_SYS_STUB_H
+
+static inline int _stub(int err)
+{
+  return -1;
+}
+
+#endif /* _SIFIVE_SYS_STUB_H */

bare-metal-bsp/libwrap/sys/times.c

@@ -0,0 +1,10 @@
+/* See LICENSE of license details. */
+
+#include <errno.h>
+#include <sys/times.h>
+#include "stub.h"
+
+clock_t __wrap_times(struct tms* buf)
+{
+  return _stub(EACCES);
+}

bare-metal-bsp/libwrap/sys/unlink.c

@@ -0,0 +1,9 @@
+/* See LICENSE of license details. */
+
+#include <errno.h>
+#include "stub.h"
+
+int __wrap_unlink(const char* name)
+{
+  return _stub(ENOENT);
+}

bare-metal-bsp/libwrap/sys/wait.c

@@ -0,0 +1,9 @@
+/* See LICENSE of license details. */
+
+#include <errno.h>
+#include "stub.h"
+
+int wait(int* status)
+{
+  return _stub(ECHILD);
+}

bare-metal-bsp/libwrap/sys/write.c

@@ -0,0 +1,29 @@
+/* See LICENSE of license details. */
+
+#include <stdint.h>
+#include <errno.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+#include "platform.h"
+#include "stub.h"
+
+ssize_t __wrap_write(int fd, const void* ptr, size_t len)
+{
+  const uint8_t * current = (const char *)ptr;
+
+  if (isatty(fd)) {
+    for (size_t jj = 0; jj < len; jj++) {
+      while (UART0_REG(UART_REG_TXFIFO) & 0x80000000) ;
+      UART0_REG(UART_REG_TXFIFO) = current[jj];
+
+      if (current[jj] == '\n') {
+        while (UART0_REG(UART_REG_TXFIFO) & 0x80000000) ;
+        UART0_REG(UART_REG_TXFIFO) = '\r';
+      }
+    }
+    return len;
+  }
+
+  return _stub(EBADF);
+}