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Message-ID: <20231122121235.827122-8-peterlin@andestech.com>
Date: Wed, 22 Nov 2023 20:12:29 +0800
From: Yu Chien Peter Lin <peterlin@...estech.com>
To: <acme@...nel.org>, <adrian.hunter@...el.com>,
<ajones@...tanamicro.com>, <alexander.shishkin@...ux.intel.com>,
<andre.przywara@....com>, <anup@...infault.org>,
<aou@...s.berkeley.edu>, <atishp@...shpatra.org>,
<conor+dt@...nel.org>, <conor.dooley@...rochip.com>,
<conor@...nel.org>, <devicetree@...r.kernel.org>,
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<geert+renesas@...der.be>, <guoren@...nel.org>, <heiko@...ech.de>,
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<jolsa@...nel.org>, <jszhang@...nel.org>,
<krzysztof.kozlowski+dt@...aro.org>,
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<linux-riscv@...ts.infradead.org>, <linux-sunxi@...ts.linux.dev>,
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<namhyung@...nel.org>, <palmer@...belt.com>,
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Subject: [PATCH v4 07/13] RISC-V: Move T-Head PMU to CPU feature alternative framework
The custom PMU extension aims to support perf event sampling prior
to the ratification of Sscofpmf. Instead of diverting the bits and
register reserved for future standard, a set of custom registers is
added. Hence, we may consider it as a CPU feature rather than an
erratum.
T-Head cores need to append "xtheadpmu" to the riscv,isa-extensions
for each cpu node in device tree, and enable CONFIG_THEAD_CUSTOM_PMU
for proper functioning as of this commit.
Signed-off-by: Yu Chien Peter Lin <peterlin@...estech.com>
---
Hi All,
This is in preparation for introducing other PMU alternative.
We follow Conor's suggestion [1][2] to use cpu feature alternative
framework rather than errata, I'm happy to drop the patch if someone
is willing to take care of this for T-Head's platforms (or sticking
with CPU errata alternative?)
[1] https://patchwork.kernel.org/project/linux-riscv/patch/20230907021635.1002738-4-peterlin@andestech.com/#25503860
[2] https://patchwork.kernel.org/project/linux-riscv/patch/20231023004100.2663486-8-peterlin@andestech.com/#25565650
Changes v1 -> v2:
- New patch
Changes v2 -> v3:
- Removed m{vendor/arch/imp}id checks in pmu_sbi_setup_irqs()
Changes v3 -> v4:
- No change
---
arch/riscv/Kconfig.errata | 13 -------------
arch/riscv/errata/thead/errata.c | 19 -------------------
arch/riscv/include/asm/errata_list.h | 15 +--------------
arch/riscv/include/asm/hwcap.h | 1 +
arch/riscv/kernel/cpufeature.c | 1 +
drivers/perf/Kconfig | 13 +++++++++++++
drivers/perf/riscv_pmu_sbi.c | 19 ++++++++++++++-----
7 files changed, 30 insertions(+), 51 deletions(-)
diff --git a/arch/riscv/Kconfig.errata b/arch/riscv/Kconfig.errata
index e2c731cfed8c..0d19f47d1018 100644
--- a/arch/riscv/Kconfig.errata
+++ b/arch/riscv/Kconfig.errata
@@ -86,17 +86,4 @@ config ERRATA_THEAD_CMO
If you don't know what to do here, say "Y".
-config ERRATA_THEAD_PMU
- bool "Apply T-Head PMU errata"
- depends on ERRATA_THEAD && RISCV_PMU_SBI
- default y
- help
- The T-Head C9xx cores implement a PMU overflow extension very
- similar to the core SSCOFPMF extension.
-
- This will apply the overflow errata to handle the non-standard
- behaviour via the regular SBI PMU driver and interface.
-
- If you don't know what to do here, say "Y".
-
endmenu # "CPU errata selection"
diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c
index 0554ed4bf087..5de5f7209132 100644
--- a/arch/riscv/errata/thead/errata.c
+++ b/arch/riscv/errata/thead/errata.c
@@ -53,22 +53,6 @@ static bool errata_probe_cmo(unsigned int stage,
return true;
}
-static bool errata_probe_pmu(unsigned int stage,
- unsigned long arch_id, unsigned long impid)
-{
- if (!IS_ENABLED(CONFIG_ERRATA_THEAD_PMU))
- return false;
-
- /* target-c9xx cores report arch_id and impid as 0 */
- if (arch_id != 0 || impid != 0)
- return false;
-
- if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
- return false;
-
- return true;
-}
-
static u32 thead_errata_probe(unsigned int stage,
unsigned long archid, unsigned long impid)
{
@@ -80,9 +64,6 @@ static u32 thead_errata_probe(unsigned int stage,
if (errata_probe_cmo(stage, archid, impid))
cpu_req_errata |= BIT(ERRATA_THEAD_CMO);
- if (errata_probe_pmu(stage, archid, impid))
- cpu_req_errata |= BIT(ERRATA_THEAD_PMU);
-
return cpu_req_errata;
}
diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h
index 4ed21a62158c..9bccc2ba0eb5 100644
--- a/arch/riscv/include/asm/errata_list.h
+++ b/arch/riscv/include/asm/errata_list.h
@@ -25,8 +25,7 @@
#ifdef CONFIG_ERRATA_THEAD
#define ERRATA_THEAD_PBMT 0
#define ERRATA_THEAD_CMO 1
-#define ERRATA_THEAD_PMU 2
-#define ERRATA_THEAD_NUMBER 3
+#define ERRATA_THEAD_NUMBER 2
#endif
#ifdef __ASSEMBLY__
@@ -147,18 +146,6 @@ asm volatile(ALTERNATIVE_2( \
"r"((unsigned long)(_start) + (_size)) \
: "a0")
-#define THEAD_C9XX_RV_IRQ_PMU 17
-#define THEAD_C9XX_CSR_SCOUNTEROF 0x5c5
-
-#define ALT_SBI_PMU_OVERFLOW(__ovl) \
-asm volatile(ALTERNATIVE( \
- "csrr %0, " __stringify(CSR_SSCOUNTOVF), \
- "csrr %0, " __stringify(THEAD_C9XX_CSR_SCOUNTEROF), \
- THEAD_VENDOR_ID, ERRATA_THEAD_PMU, \
- CONFIG_ERRATA_THEAD_PMU) \
- : "=r" (__ovl) : \
- : "memory")
-
#endif /* __ASSEMBLY__ */
#endif
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index 06d30526ef3b..c85ee34c78d9 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -57,6 +57,7 @@
#define RISCV_ISA_EXT_ZIHPM 42
#define RISCV_ISA_EXT_SMSTATEEN 43
#define RISCV_ISA_EXT_ZICOND 44
+#define RISCV_ISA_EXT_XTHEADPMU 45
#define RISCV_ISA_EXT_MAX 64
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index b3785ffc1570..e606f588d366 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -185,6 +185,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
__RISCV_ISA_EXT_DATA(svinval, RISCV_ISA_EXT_SVINVAL),
__RISCV_ISA_EXT_DATA(svnapot, RISCV_ISA_EXT_SVNAPOT),
__RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT),
+ __RISCV_ISA_EXT_DATA(xtheadpmu, RISCV_ISA_EXT_XTHEADPMU),
};
const size_t riscv_isa_ext_count = ARRAY_SIZE(riscv_isa_ext);
diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
index 273d67ecf6d2..c71b6f16bdfa 100644
--- a/drivers/perf/Kconfig
+++ b/drivers/perf/Kconfig
@@ -86,6 +86,19 @@ config RISCV_PMU_SBI
full perf feature support i.e. counter overflow, privilege mode
filtering, counter configuration.
+config THEAD_CUSTOM_PMU
+ bool "T-Head custom PMU support"
+ depends on RISCV_ALTERNATIVE && RISCV_PMU_SBI
+ default y
+ help
+ The T-Head C9xx cores implement a PMU overflow extension very
+ similar to the core SSCOFPMF extension.
+
+ This will patch the overflow CSR and handle the non-standard
+ behaviour via the regular SBI PMU driver and interface.
+
+ If you don't know what to do here, say "Y".
+
config ARM_PMU_ACPI
depends on ARM_PMU && ACPI
def_bool y
diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
index 2edbc37abadf..31ca79846399 100644
--- a/drivers/perf/riscv_pmu_sbi.c
+++ b/drivers/perf/riscv_pmu_sbi.c
@@ -20,10 +20,21 @@
#include <linux/cpu_pm.h>
#include <linux/sched/clock.h>
-#include <asm/errata_list.h>
#include <asm/sbi.h>
#include <asm/cpufeature.h>
+#define THEAD_C9XX_RV_IRQ_PMU 17
+#define THEAD_C9XX_CSR_SCOUNTEROF 0x5c5
+
+#define ALT_SBI_PMU_OVERFLOW(__ovl) \
+asm volatile(ALTERNATIVE( \
+ "csrr %0, " __stringify(CSR_SSCOUNTOVF), \
+ "csrr %0, " __stringify(THEAD_C9XX_CSR_SCOUNTEROF), \
+ 0, RISCV_ISA_EXT_XTHEADPMU, \
+ CONFIG_THEAD_CUSTOM_PMU) \
+ : "=r" (__ovl) : \
+ : "memory")
+
#define SYSCTL_NO_USER_ACCESS 0
#define SYSCTL_USER_ACCESS 1
#define SYSCTL_LEGACY 2
@@ -808,10 +819,8 @@ static int pmu_sbi_setup_irqs(struct riscv_pmu *pmu, struct platform_device *pde
if (riscv_isa_extension_available(NULL, SSCOFPMF)) {
riscv_pmu_irq_num = RV_IRQ_PMU;
riscv_pmu_use_irq = true;
- } else if (IS_ENABLED(CONFIG_ERRATA_THEAD_PMU) &&
- riscv_cached_mvendorid(0) == THEAD_VENDOR_ID &&
- riscv_cached_marchid(0) == 0 &&
- riscv_cached_mimpid(0) == 0) {
+ } else if (riscv_isa_extension_available(NULL, XTHEADPMU) &&
+ IS_ENABLED(CONFIG_THEAD_CUSTOM_PMU)) {
riscv_pmu_irq_num = THEAD_C9XX_RV_IRQ_PMU;
riscv_pmu_use_irq = true;
}
--
2.34.1
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