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lib: sbi: Add Sscpuutil (CPU Utilization) extension support #11

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lib: sbi: Add Sscpuutil (CPU Utilization) extension support #11

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18 changes: 18 additions & 0 deletions include/sbi/riscv_encoding.h
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Original file line number Diff line number Diff line change
Expand Up @@ -265,6 +265,10 @@
#define CSR_CYCLE 0xc00
#define CSR_TIME 0xc01
#define CSR_INSTRET 0xc02

/* Sscpuutil: CPU active time counter (address TBD, using placeholder) */
#define CSR_ACTTIME 0xc31
#define CSR_ACTTIMEH 0xcb1
#define CSR_HPMCOUNTER3 0xc03
#define CSR_HPMCOUNTER4 0xc04
#define CSR_HPMCOUNTER5 0xc05
Expand Down Expand Up @@ -612,6 +616,12 @@
#define CSR_MHPMCOUNTER29 0xb1d
#define CSR_MHPMCOUNTER30 0xb1e
#define CSR_MHPMCOUNTER31 0xb1f

/* Sscpuutil: M-mode CPU active time counter (address TBD, using placeholder) */
#define CSR_MACTTIME 0xb31
#define CSR_MACTTIMEH 0xbb1
#define CSR_MCPUUTILEN 0x320
#define CSR_SCPUUTILEN 0x120
#define CSR_MCYCLEH 0xb80
#define CSR_MINSTRETH 0xb82
#define CSR_MHPMCOUNTER3H 0xb83
Expand Down Expand Up @@ -827,6 +837,14 @@
#define SMSTATEEN0_HSENVCFG (_ULL(1) << SMSTATEEN0_HSENVCFG_SHIFT)
#define SMSTATEEN_STATEN_SHIFT 63
#define SMSTATEEN_STATEN (_ULL(1) << SMSTATEEN_STATEN_SHIFT)
/* Sscpuutil: acttime access control (bit position TBD) */
#define SMSTATEEN0_CPUUTIL_SHIFT 55
#define SMSTATEEN0_CPUUTIL (_ULL(1) << SMSTATEEN0_CPUUTIL_SHIFT)

/* Sscpuutil mcpuutilen enable bits */
#define CPUUTILEN_CORECYC (1UL << 0)
#define CPUUTILEN_ACTTIME (1UL << 1)
#define CPUUTILEN_ALL (CPUUTILEN_CORECYC | CPUUTILEN_ACTTIME)

/* ===== Instruction Encodings ===== */

Expand Down
2 changes: 2 additions & 0 deletions include/sbi/sbi_hart.h
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Original file line number Diff line number Diff line change
Expand Up @@ -81,6 +81,8 @@ enum sbi_hart_extensions {
SBI_HART_EXT_SSCTR,
/** HART has Ssstateen extension **/
SBI_HART_EXT_SSSTATEEN,
/** Hart has Sscpuutil extension (CPU utilization) */
SBI_HART_EXT_SSCPUUTIL,

/** Maximum index of Hart extension */
SBI_HART_EXT_MAX,
Expand Down
46 changes: 44 additions & 2 deletions lib/sbi/sbi_hart.c
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Original file line number Diff line number Diff line change
Expand Up @@ -63,8 +63,17 @@ static void mstatus_init(struct sbi_scratch *scratch)
csr_write(CSR_MCOUNTEREN, -1);

/* All programmable counters will start running at runtime after S-mode request */
if (sbi_hart_priv_version(scratch) >= SBI_HART_PRIV_VER_1_11)
csr_write(CSR_MCOUNTINHIBIT, 0xFFFFFFF8);
if (sbi_hart_priv_version(scratch) >= SBI_HART_PRIV_VER_1_11) {
unsigned long inhibit_val = 0xFFFFFFF8;
/*
* When Sscpuutil is available, keep cycle running
* (clear mcountinhibit.CY) so that the frequency ratio
* Dcycle/Dacttime remains valid.
*/
if (sbi_hart_has_extension(scratch, SBI_HART_EXT_SSCPUUTIL))
inhibit_val &= ~(1UL << 0);
csr_write(CSR_MCOUNTINHIBIT, inhibit_val);
}

/**
* The mhpmeventn[h] CSR should be initialized with interrupt disabled
Expand Down Expand Up @@ -110,12 +119,37 @@ static void mstatus_init(struct sbi_scratch *scratch)
else
mstateen_val &= ~SMSTATEEN0_CTR;

if (sbi_hart_has_extension(scratch, SBI_HART_EXT_SSCPUUTIL))
mstateen_val |= SMSTATEEN0_CPUUTIL;
else
mstateen_val &= ~SMSTATEEN0_CPUUTIL;

csr_write64(CSR_MSTATEEN0, mstateen_val);
csr_write64(CSR_MSTATEEN1, SMSTATEEN_STATEN);
csr_write64(CSR_MSTATEEN2, SMSTATEEN_STATEN);
csr_write64(CSR_MSTATEEN3, SMSTATEEN_STATEN);
}

/*
* For platforms with dedicated mcpuutilen (Sscpuutil-style),
* enable both counters for S/U-mode access.
* Directly probe the CSR since extension detection may not
* cover all naming variants (sscpuutil vs sscpuutil).
*/
{
struct sbi_trap_info __trap = {0};
csr_read_allowed(CSR_MCPUUTILEN, &__trap);
if (!__trap.cause) {
csr_write(CSR_MCPUUTILEN, CPUUTILEN_ALL);
csr_write(CSR_SCPUUTILEN, CPUUTILEN_ALL);
sbi_printf("mcpuutilen/scpuutilen: set to 0x%lx (direct probe)\n",
(unsigned long)CPUUTILEN_ALL);
} else {
sbi_printf("mcpuutilen: CSR not present (cause=%lu)\n",
__trap.cause);
}
}

if (sbi_hart_has_extension(scratch, SBI_HART_EXT_SSSTATEEN)) {
if (misa_extension('S')) {
csr_write(CSR_SSTATEEN0, 0);
Expand Down Expand Up @@ -715,6 +749,7 @@ const struct sbi_hart_ext_data sbi_hart_ext[] = {
__SBI_HART_EXT_DATA(smctr, SBI_HART_EXT_SMCTR),
__SBI_HART_EXT_DATA(ssctr, SBI_HART_EXT_SSCTR),
__SBI_HART_EXT_DATA(ssstateen, SBI_HART_EXT_SSSTATEEN),
__SBI_HART_EXT_DATA(sscpuutil, SBI_HART_EXT_SSCPUUTIL),
};

_Static_assert(SBI_HART_EXT_MAX == array_size(sbi_hart_ext),
Expand Down Expand Up @@ -959,6 +994,13 @@ static int hart_detect_features(struct sbi_scratch *scratch)
}

/* Counter overflow/filtering is not useful without mcounter/inhibit */
/* Detect if hart supports Sscpuutil (CPU utilization) */
csr_read_allowed(CSR_MACTTIME, &trap);
sbi_printf("SSCPUUTIL: CSR_MACTTIME(0xb21) probe: trap.cause=%lu\n",
trap.cause);
__check_ext_csr(SBI_HART_PRIV_VER_1_12,
CSR_MACTTIME, SBI_HART_EXT_SSCPUUTIL);

/* Detect if hart supports sscofpmf */
__check_ext_csr(SBI_HART_PRIV_VER_1_11,
CSR_SCOUNTOVF, SBI_HART_EXT_SSCOFPMF);
Expand Down
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