lib: utils/irqchip: Add FDT based driver for IMSIC

We add simple FDT irqchip driver for IMSIC so that generic platform
(and other FDT based platforms) can utilize common IMIC library.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>

include/sbi_utils/fdt/fdt_helper.h

@@ -68,6 +68,12 @@ int fdt_parse_uart8250_node(void *fdt, int nodeoffset,
 int fdt_parse_uart8250(void *fdt, struct platform_uart_data *uart,
 		       const char *compatible);
 
+struct imsic_data;
+
+bool fdt_check_imsic_mlevel(void *fdt);
+
+int fdt_parse_imsic_node(void *fdt, int nodeoff, struct imsic_data *imsic);
+
 struct plic_data;
 
 int fdt_parse_plic_node(void *fdt, int nodeoffset, struct plic_data *plic);

lib/utils/fdt/fdt_helper.c

@@ -13,6 +13,7 @@
 #include <sbi/sbi_platform.h>
 #include <sbi/sbi_scratch.h>
 #include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi_utils/irqchip/imsic.h>
 #include <sbi_utils/irqchip/plic.h>
 
 #define DEFAULT_UART_FREQ		0
@@ -465,6 +466,108 @@ int fdt_parse_uart8250(void *fdt, struct platform_uart_data *uart,
 	return fdt_parse_uart8250_node(fdt, nodeoffset, uart);
 }
 
+bool fdt_check_imsic_mlevel(void *fdt)
+{
+	const fdt32_t *val;
+	int i, len, noff = 0;
+
+	if (!fdt)
+		return false;
+
+	while ((noff = fdt_node_offset_by_compatible(fdt, noff,
+						     "riscv,imsics")) >= 0) {
+		val = fdt_getprop(fdt, noff, "interrupts-extended", &len);
+		if (val && len > sizeof(fdt32_t)) {
+			len = len / sizeof(fdt32_t);
+			for (i = 0; i < len; i += 2) {
+				if (fdt32_to_cpu(val[i + 1]) == IRQ_M_EXT)
+					return true;
+			}
+		}
+	}
+
+	return false;
+}
+
+int fdt_parse_imsic_node(void *fdt, int nodeoff, struct imsic_data *imsic)
+{
+	const fdt32_t *val;
+	struct imsic_regs *regs;
+	uint64_t reg_addr, reg_size;
+	int i, rc, len, nr_parent_irqs;
+
+	if (nodeoff < 0 || !imsic || !fdt)
+		return SBI_ENODEV;
+
+	imsic->targets_mmode = false;
+	val = fdt_getprop(fdt, nodeoff, "interrupts-extended", &len);
+	if (val && len > sizeof(fdt32_t)) {
+		len = len / sizeof(fdt32_t);
+		nr_parent_irqs = len / 2;
+		for (i = 0; i < len; i += 2) {
+			if (fdt32_to_cpu(val[i + 1]) == IRQ_M_EXT) {
+				imsic->targets_mmode = true;
+				break;
+			}
+		}
+	} else
+		return SBI_EINVAL;
+
+	val = fdt_getprop(fdt, nodeoff, "riscv,guest-index-bits", &len);
+	if (val && len > 0)
+		imsic->guest_index_bits = fdt32_to_cpu(*val);
+	else
+		imsic->guest_index_bits = 0;
+
+	val = fdt_getprop(fdt, nodeoff, "riscv,hart-index-bits", &len);
+	if (val && len > 0) {
+		imsic->hart_index_bits = fdt32_to_cpu(*val);
+	} else {
+		imsic->hart_index_bits = sbi_fls(nr_parent_irqs);
+		if ((1UL << imsic->hart_index_bits) < nr_parent_irqs)
+			imsic->hart_index_bits++;
+	}
+
+	val = fdt_getprop(fdt, nodeoff, "riscv,group-index-bits", &len);
+	if (val && len > 0)
+		imsic->group_index_bits = fdt32_to_cpu(*val);
+	else
+		imsic->group_index_bits = 0;
+
+	val = fdt_getprop(fdt, nodeoff, "riscv,group-index-shift", &len);
+	if (val && len > 0)
+		imsic->group_index_shift = fdt32_to_cpu(*val);
+	else
+		imsic->group_index_shift = 2 * IMSIC_MMIO_PAGE_SHIFT;
+
+	val = fdt_getprop(fdt, nodeoff, "riscv,num-ids", &len);
+	if (val && len > 0)
+		imsic->num_ids = fdt32_to_cpu(*val);
+	else
+		return SBI_EINVAL;
+
+	for (i = 0; i < IMSIC_MAX_REGS; i++) {
+		regs = &imsic->regs[i];
+		regs->addr = 0;
+		regs->size = 0;
+	}
+
+	for (i = 0; i < (IMSIC_MAX_REGS - 1); i++) {
+		regs = &imsic->regs[i];
+
+		rc = fdt_get_node_addr_size(fdt, nodeoff, i,
+					    &reg_addr, &reg_size);
+		if (rc < 0 || !reg_addr || !reg_size)
+			break;
+		regs->addr = reg_addr;
+		regs->size = reg_size;
+	};
+	if (!imsic->regs[0].size)
+		return SBI_EINVAL;
+
+	return 0;
+}
+
 int fdt_parse_plic_node(void *fdt, int nodeoffset, struct plic_data *plic)
 {
 	int len, rc;

lib/utils/irqchip/fdt_irqchip.c

@@ -12,9 +12,11 @@
 #include <sbi_utils/fdt/fdt_helper.h>
 #include <sbi_utils/irqchip/fdt_irqchip.h>
 
+extern struct fdt_irqchip fdt_irqchip_imsic;
 extern struct fdt_irqchip fdt_irqchip_plic;
 
 static struct fdt_irqchip *irqchip_drivers[] = {
+	&fdt_irqchip_imsic,
 	&fdt_irqchip_plic
 };
 

lib/utils/irqchip/fdt_irqchip_imsic.c

@@ -0,0 +1,106 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2021 Western Digital Corporation or its affiliates.
+ * Copyright (c) 2022 Ventana Micro Systems Inc.
+ *
+ * Authors:
+ *   Anup Patel <anup.patel@wdc.com>
+ */
+
+#include <libfdt.h>
+#include <sbi/riscv_asm.h>
+#include <sbi/sbi_error.h>
+#include <sbi/sbi_hartmask.h>
+#include <sbi_utils/fdt/fdt_helper.h>
+#include <sbi_utils/irqchip/fdt_irqchip.h>
+#include <sbi_utils/irqchip/imsic.h>
+
+#define IMSIC_MAX_NR			16
+
+static unsigned long imsic_count = 0;
+static struct imsic_data imsic[IMSIC_MAX_NR];
+
+static int irqchip_imsic_update_hartid_table(void *fdt, int nodeoff,
+					     struct imsic_data *id)
+{
+	const fdt32_t *val;
+	u32 phandle, hwirq, hartid;
+	int i, err, count, cpu_offset, cpu_intc_offset;
+
+	val = fdt_getprop(fdt, nodeoff, "interrupts-extended", &count);
+	if (!val || count < sizeof(fdt32_t))
+		return SBI_EINVAL;
+	count = count / sizeof(fdt32_t);
+
+	for (i = 0; i < count; i += 2) {
+		phandle = fdt32_to_cpu(val[i]);
+		hwirq = fdt32_to_cpu(val[i + 1]);
+
+		cpu_intc_offset = fdt_node_offset_by_phandle(fdt, phandle);
+		if (cpu_intc_offset < 0)
+			continue;
+
+		cpu_offset = fdt_parent_offset(fdt, cpu_intc_offset);
+		if (cpu_intc_offset < 0)
+			continue;
+
+		err = fdt_parse_hart_id(fdt, cpu_offset, &hartid);
+		if (err)
+			return SBI_EINVAL;
+		if (SBI_HARTMASK_MAX_BITS <= hartid)
+			return SBI_EINVAL;
+
+		switch (hwirq) {
+		case IRQ_M_EXT:
+			err = imsic_map_hartid_to_data(hartid, id, i / 2);
+			if (err)
+				return err;
+			break;
+		default:
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static int irqchip_imsic_cold_init(void *fdt, int nodeoff,
+				    const struct fdt_match *match)
+{
+	int rc;
+	struct imsic_data *id;
+
+	if (IMSIC_MAX_NR <= imsic_count)
+		return SBI_ENOSPC;
+	id = &imsic[imsic_count];
+
+	rc = fdt_parse_imsic_node(fdt, nodeoff, id);
+	if (rc)
+		return rc;
+	if (!id->targets_mmode)
+		return 0;
+
+	rc = irqchip_imsic_update_hartid_table(fdt, nodeoff, id);
+	if (rc)
+		return rc;
+
+	rc = imsic_cold_irqchip_init(id);
+	if (rc)
+		return rc;
+
+	imsic_count++;
+
+	return 0;
+}
+
+static const struct fdt_match irqchip_imsic_match[] = {
+	{ .compatible = "riscv,imsics" },
+	{ },
+};
+
+struct fdt_irqchip fdt_irqchip_imsic = {
+	.match_table = irqchip_imsic_match,
+	.cold_init = irqchip_imsic_cold_init,
+	.warm_init = imsic_warm_irqchip_init,
+};

lib/utils/irqchip/objects.mk

@@ -8,6 +8,7 @@
 #
 
 libsbiutils-objs-y += irqchip/fdt_irqchip.o
+libsbiutils-objs-y += irqchip/fdt_irqchip_imsic.o
 libsbiutils-objs-y += irqchip/fdt_irqchip_plic.o
 libsbiutils-objs-y += irqchip/imsic.o
 libsbiutils-objs-y += irqchip/plic.o

platform/generic/platform.c

@@ -18,6 +18,7 @@
 #include <sbi_utils/fdt/fdt_helper.h>
 #include <sbi_utils/fdt/fdt_pmu.h>
 #include <sbi_utils/irqchip/fdt_irqchip.h>
+#include <sbi_utils/irqchip/imsic.h>
 #include <sbi_utils/serial/fdt_serial.h>
 #include <sbi_utils/timer/fdt_timer.h>
 #include <sbi_utils/ipi/fdt_ipi.h>
@@ -56,6 +57,7 @@ static void fw_platform_lookup_special(void *fdt, int root_offset)
 }
 
 extern struct sbi_platform platform;
+static bool platform_has_mlevel_imsic = false;
 static u32 generic_hart_index2id[SBI_HARTMASK_MAX_BITS] = { 0 };
 
 /*
@@ -110,6 +112,8 @@ unsigned long fw_platform_init(unsigned long arg0, unsigned long arg1,
 
 	platform.hart_count = hart_count;
 
+	platform_has_mlevel_imsic = fdt_check_imsic_mlevel(fdt);
+
 	/* Return original FDT pointer */
 	return arg1;
 
@@ -118,6 +122,13 @@ fail:
 		wfi();
 }
 
+static int generic_nascent_init(void)
+{
+	if (platform_has_mlevel_imsic)
+		imsic_local_irqchip_init();
+	return 0;
+}
+
 static int generic_early_init(bool cold_boot)
 {
 	if (!generic_plat || !generic_plat->early_init)
@@ -210,6 +221,7 @@ static uint64_t generic_pmu_xlate_to_mhpmevent(uint32_t event_idx,
 }
 
 const struct sbi_platform_operations platform_ops = {
+	.nascent_init		= generic_nascent_init,
 	.early_init		= generic_early_init,
 	.final_init		= generic_final_init,
 	.early_exit		= generic_early_exit,