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lib: sbi: Detect number of bits implemented in mhpmcounter

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RISC-V privilege specification allows the implementation to have less
than 64 bits.

Add a function to detect the number of implemented bits in mhpmcounter
dynamically at runtime.

Reviewed-by: Xiang W <wxjstz@126.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
Signed-off-by: Atish Patra <atish.patra@wdc.com>
This commit is contained in:
Atish Patra
2021-07-10 09:18:05 -07:00
committed by Anup Patel
parent d3a96cc469
commit 0829f2bc28
2 changed files with 49 additions and 0 deletions
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1
include/sbi/sbi_hart.h
View File

@@ -44,6 +44,7 @@ void sbi_hart_delegation_dump(struct sbi_scratch *scratch,
unsigned int sbi_hart_pmp_count(struct sbi_scratch *scratch);
unsigned long sbi_hart_pmp_granularity(struct sbi_scratch *scratch);
unsigned int sbi_hart_pmp_addrbits(struct sbi_scratch *scratch);
unsigned int sbi_hart_mhpm_bits(struct sbi_scratch *scratch);
int sbi_hart_pmp_configure(struct sbi_scratch *scratch);
bool sbi_hart_has_feature(struct sbi_scratch *scratch, unsigned long feature);
void sbi_hart_get_features_str(struct sbi_scratch *scratch,

48
lib/sbi/sbi_hart.c
View File

@@ -33,6 +33,7 @@ struct hart_features {
unsigned int pmp_addr_bits;
unsigned long pmp_gran;
unsigned int mhpm_count;
unsigned int mhpm_bits;
};
static unsigned long hart_features_offset;
@@ -177,6 +178,14 @@ unsigned int sbi_hart_pmp_addrbits(struct sbi_scratch *scratch)
return hfeatures->pmp_addr_bits;
}
unsigned int sbi_hart_mhpm_bits(struct sbi_scratch *scratch)
{
struct hart_features *hfeatures =
sbi_scratch_offset_ptr(scratch, hart_features_offset);
return hfeatures->mhpm_bits;
}
int sbi_hart_pmp_configure(struct sbi_scratch *scratch)
{
struct sbi_domain_memregion *reg;
@@ -330,6 +339,37 @@ static unsigned long hart_pmp_get_allowed_addr(void)
return val;
}
static int hart_pmu_get_allowed_bits(void)
{
unsigned long val = ~(0UL);
struct sbi_trap_info trap = {0};
int num_bits = 0;
/**
* It is assumed that platforms will implement same number of bits for
* all the performance counters including mcycle/minstret.
*/
csr_write_allowed(CSR_MHPMCOUNTER3, (ulong)&trap, val);
if (!trap.cause) {
val = csr_read_allowed(CSR_MHPMCOUNTER3, (ulong)&trap);
if (trap.cause)
return 0;
}
num_bits = __fls(val) + 1;
#if __riscv_xlen == 32
csr_write_allowed(CSR_MHPMCOUNTER3H, (ulong)&trap, val);
if (!trap.cause) {
val = csr_read_allowed(CSR_MHPMCOUNTER3H, (ulong)&trap);
if (trap.cause)
return num_bits;
}
num_bits += __fls(val) + 1;
#endif
return num_bits;
}
static void hart_detect_features(struct sbi_scratch *scratch)
{
struct sbi_trap_info trap = {0};
@@ -395,9 +435,17 @@ __pmp_skip:
/* Detect number of MHPM counters */
__check_csr(CSR_MHPMCOUNTER3, 0, 1UL, mhpm_count, __mhpm_skip);
hfeatures->mhpm_bits = hart_pmu_get_allowed_bits();
__check_csr_4(CSR_MHPMCOUNTER4, 0, 1UL, mhpm_count, __mhpm_skip);
__check_csr_8(CSR_MHPMCOUNTER8, 0, 1UL, mhpm_count, __mhpm_skip);
__check_csr_16(CSR_MHPMCOUNTER16, 0, 1UL, mhpm_count, __mhpm_skip);
/**
* No need to check for MHPMCOUNTERH for RV32 as they are expected to be
* implemented if MHPMCOUNTER is implemented.
*/
__mhpm_skip:
#undef __check_csr_64