[PATCH v3 1/4] RISC-V: Create unique identification for SoC PMU

Nikita Shubin
2022-06-07T13:18:43Z

From: João Mário Domingos <joao.mario@tecnico.ulisboa.pt>

The SBI PMU platform driver did not provide any identification for
perf events matching. This patch introduces a new sysfs file inside the
platform device (soc:pmu/id) for pmu identification.

The identification is a 64-bit value generated as:
[63-32]: mvendorid;
[31]: marchid[MSB];
[30-16]: marchid[15-0];
[15-0]: mimpid[15MSBs];

The CSRs are detailed in the RISC-V privileged spec [1].
The marchid is split in MSB + 15LSBs, due to the MSB being used for
open-source architecture identification.

[1] https://github.com/riscv/riscv-isa-manual

Signed-off-by: João Mário Domingos <joao.mario@tecnico.ulisboa.pt>
Tested-by: Nikita Shubin <n.shubin@yadro.com>
---
arch/riscv/kernel/sbi.c | 3 +++
drivers/perf/riscv_pmu_sbi.c | 47 ++++++++++++++++++++++++++++++++++++
2 files changed, 50 insertions(+)

diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
index 775d3322b422..50dd9b6ecc9e 100644
--- a/arch/riscv/kernel/sbi.c
+++ b/arch/riscv/kernel/sbi.c
@@ -627,16 +627,19 @@ long sbi_get_mvendorid(void)
{
return __sbi_base_ecall(SBI_EXT_BASE_GET_MVENDORID);
}
+EXPORT_SYMBOL(sbi_get_mvendorid);

long sbi_get_marchid(void)
{
return __sbi_base_ecall(SBI_EXT_BASE_GET_MARCHID);
}
+EXPORT_SYMBOL(sbi_get_marchid);

long sbi_get_mimpid(void)
{
return __sbi_base_ecall(SBI_EXT_BASE_GET_MIMPID);
}
+EXPORT_SYMBOL(sbi_get_mimpid);

static void sbi_send_cpumask_ipi(const struct cpumask *target)
{
diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
index a1317a483512..15ab3dc68e7a 100644
--- a/drivers/perf/riscv_pmu_sbi.c
+++ b/drivers/perf/riscv_pmu_sbi.c
@@ -693,6 +693,46 @@ static int pmu_sbi_setup_irqs(struct riscv_pmu *pmu, struct platform_device *pde
return 0;
}

+static uint64_t pmu_sbi_get_pmu_id(void)
+{
+ union sbi_pmu_id {
+ uint64_t value;
+ struct {
+ uint16_t imp:16;
+ uint16_t arch:16;
+ uint32_t vendor:32;
+ };
+ } pmuid;
+
+ pmuid.value = 0;
+ pmuid.vendor = (uint32_t) sbi_get_mvendorid();
+ pmuid.arch = (sbi_get_marchid() >> (63 - 15) & (1 << 15)) | (sbi_get_marchid() & 0x7FFF);
+ pmuid.imp = (sbi_get_mimpid() >> 16);
+
+ return pmuid.value;
+}
+
+static ssize_t pmu_sbi_id_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ int len;
+
+ len = sprintf(buf, "0x%llx\n", pmu_sbi_get_pmu_id());
+ if (len <= 0)
+ dev_err(dev, "mydrv: Invalid sprintf len: %dn", len);
+
+ return len;
+}
+
+static DEVICE_ATTR(id, S_IRUGO | S_IWUSR, pmu_sbi_id_show, 0);
+
+static struct attribute *pmu_sbi_attrs[] = {
+ &dev_attr_id.attr,
+ NULL
+};
+
+ATTRIBUTE_GROUPS(pmu_sbi);
+
static int pmu_sbi_device_probe(struct platform_device *pdev)
{
struct riscv_pmu *pmu = NULL;
@@ -729,6 +769,13 @@ static int pmu_sbi_device_probe(struct platform_device *pdev)
pmu->ctr_clear_idx = pmu_sbi_ctr_clear_idx;
pmu->ctr_read = pmu_sbi_ctr_read;

+ ret = sysfs_create_group(&pdev->dev.kobj, &pmu_sbi_group);
+ if (ret) {
+ dev_err(&pdev->dev, "sysfs creation failed\n");
+ return ret;
+ }
+ pdev->dev.groups = pmu_sbi_groups;
+
ret = cpuhp_state_add_instance(CPUHP_AP_PERF_RISCV_STARTING, &pmu->node);
if (ret)
return ret;
--
2.35.1