[PATCH v2 2/4] RISC-V: Support CPUID for risc-v in perf

[João Mário Domingos]

This patch creates the header.c file for the risc-v architecture and introduces support for
PMU identification through sysfs.
It is now possible to configure pmu-events in risc-v.

Depends on patch [1], that introduces the id sysfs file.

Signed-off-by: João Mário Domingos <joao.mario at tecnico.ulisboa.pt>
---
 drivers/perf/riscv_pmu.c            | 18 ++++++++
 tools/perf/arch/riscv/util/Build    |  1 +
 tools/perf/arch/riscv/util/header.c | 66 +++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+)
 create mode 100644 tools/perf/arch/riscv/util/header.c

diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
index 0c853e23f679..3752ffd4edaf 100644
--- a/drivers/perf/riscv_pmu.c
+++ b/drivers/perf/riscv_pmu.c
@@ -17,6 +17,23 @@
 
 #include <asm/sbi.h>
 
+PMU_FORMAT_ATTR(event, "config:0-63");
+
+static struct attribute *riscv_arch_formats_attr[] = {
+	&format_attr_event.attr,
+	NULL,
+};
+
+static struct attribute_group riscv_pmu_format_group = {
+	.name = "format",
+	.attrs = riscv_arch_formats_attr,
+};
+
+static const struct attribute_group *riscv_pmu_attr_groups[] = {
+	&riscv_pmu_format_group,
+	NULL,
+};
+
 static unsigned long csr_read_num(int csr_num)
 {
 #define switchcase_csr_read(__csr_num, __val)		{\
@@ -314,6 +331,7 @@ struct riscv_pmu *riscv_pmu_alloc(void)
 			cpuc->events[i] = NULL;
 	}
 	pmu->pmu = (struct pmu) {
+		.attr_groups	= riscv_pmu_attr_groups,
 		.event_init	= riscv_pmu_event_init,
 		.add		= riscv_pmu_add,
 		.del		= riscv_pmu_del,
diff --git a/tools/perf/arch/riscv/util/Build b/tools/perf/arch/riscv/util/Build
index 7d3050134ae0..603dbb5ae4dc 100644
--- a/tools/perf/arch/riscv/util/Build
+++ b/tools/perf/arch/riscv/util/Build
@@ -1,4 +1,5 @@
 perf-y += perf_regs.o
+perf-y += header.o
 
 perf-$(CONFIG_DWARF) += dwarf-regs.o
 perf-$(CONFIG_LIBDW_DWARF_UNWIND) += unwind-libdw.o
diff --git a/tools/perf/arch/riscv/util/header.c b/tools/perf/arch/riscv/util/header.c
new file mode 100644
index 000000000000..b4ca8a768f11
--- /dev/null
+++ b/tools/perf/arch/riscv/util/header.c
@@ -0,0 +1,66 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <api/fs/fs.h>
+#include <errno.h>
+#include "../../util/debug.h"
+#include "../../util/header.h"
+
+#define STR_LEN 1024
+#define ID_SIZE 64
+
+static int _get_cpuid(char *buf, size_t sz)
+{
+	const char *sysfs = sysfs__mountpoint();
+	u64 id = 0;
+	char path[PATH_MAX];
+	FILE *file;
+
+	if (!sysfs || sz < ID_SIZE)
+		return -EINVAL;
+
+	scnprintf(path, PATH_MAX, "%s/devices/platform/soc/soc:pmu/id",
+			sysfs);
+
+	file = fopen(path, "r");
+	if (!file) {
+		pr_debug("fopen failed for file %s\n", path);
+		return -EINVAL;
+	}
+	if (!fgets(buf, ID_SIZE, file)) {
+		fclose(file);
+		return -EINVAL;
+	}
+
+	fclose(file);
+
+	/*Check if value is numeric and remove special characters*/
+	id = strtoul(buf, NULL, 16);
+	if (!id)
+		return -EINVAL;
+	scnprintf(buf, ID_SIZE, "0x%lx", id);
+
+	return 0;
+}
+
+char *get_cpuid_str(struct perf_pmu *pmu __maybe_unused)
+{
+	char *buf = NULL;
+	int res;
+
+	if (!pmu)
+		return NULL;
+
+	buf = malloc(ID_SIZE);
+	if (!buf)
+		return NULL;
+
+	/* read id */
+	res = _get_cpuid(buf, ID_SIZE);
+	if (res) {
+		pr_err("failed to get cpuid string for PMU %s\n", pmu->name);
+		free(buf);
+		buf = NULL;
+	}
+
+	return buf;
+}
-- 
2.17.1