[PATCH V4 2/4] arm_pmu: acpi: Add a representative platform device for TRBE

Anshuman Khandual
2023-08-08T08:23:37Z

ACPI TRBE does not have a HID for identification which could create and add
a platform device into the platform bus. Also without a platform device, it
cannot be probed and bound to a platform driver.

This creates a dummy platform device for TRBE after ascertaining that ACPI
provides required interrupts uniformly across all cpus on the system. This
device gets created inside drivers/perf/arm_pmu_acpi.c to accommodate TRBE
being built as a module.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
arch/arm64/include/asm/acpi.h | 3 +++
drivers/perf/arm_pmu_acpi.c | 35 +++++++++++++++++++++++++++++++++++
include/linux/perf/arm_pmu.h | 1 +
3 files changed, 39 insertions(+)

diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
index bd68e1b7f29f..4d537d56eb84 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -42,6 +42,9 @@
#define ACPI_MADT_GICC_SPE (offsetof(struct acpi_madt_generic_interrupt, \
spe_interrupt) + sizeof(u16))

+#define ACPI_MADT_GICC_TRBE (offsetof(struct acpi_madt_generic_interrupt, \
+ trbe_interrupt) + sizeof(u16))
+
/* Basic configuration for ACPI */
#ifdef CONFIG_ACPI
pgprot_t __acpi_get_mem_attribute(phys_addr_t addr);
diff --git a/drivers/perf/arm_pmu_acpi.c b/drivers/perf/arm_pmu_acpi.c
index 72454bef2a70..845683ca7c64 100644
--- a/drivers/perf/arm_pmu_acpi.c
+++ b/drivers/perf/arm_pmu_acpi.c
@@ -164,6 +164,40 @@ static inline void arm_spe_acpi_register_device(void)
}
#endif /* CONFIG_ARM_SPE_PMU */

+#if IS_ENABLED(CONFIG_CORESIGHT_TRBE)
+static struct resource trbe_resources[] = {
+ {
+ /* irq */
+ .flags = IORESOURCE_IRQ,
+ }
+};
+
+static struct platform_device trbe_dev = {
+ .name = ARMV8_TRBE_PDEV_NAME,
+ .id = -1,
+ .resource = trbe_resources,
+ .num_resources = ARRAY_SIZE(trbe_resources)
+};
+
+static u16 arm_trbe_parse_gsi(struct acpi_madt_generic_interrupt *gicc)
+{
+ return gicc->trbe_interrupt;
+}
+
+static void arm_trbe_acpi_register_device(void)
+{
+ int ret = arm_acpi_register_pmu_device(&trbe_dev, ACPI_MADT_GICC_TRBE,
+ arm_trbe_parse_gsi);
+ if (ret)
+ pr_warn("ACPI: TRBE: Unable to register device\n");
+}
+#else
+static inline void arm_trbe_acpi_register_device(void)
+{
+
+}
+#endif /* CONFIG_CORESIGHT_TRBE */
+
static int arm_pmu_acpi_parse_irqs(void)
{
int irq, cpu, irq_cpu, err;
@@ -399,6 +433,7 @@ static int arm_pmu_acpi_init(void)
return 0;

arm_spe_acpi_register_device();
+ arm_trbe_acpi_register_device();

return 0;
}
diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
index a0801f68762b..143fbc10ecfe 100644
--- a/include/linux/perf/arm_pmu.h
+++ b/include/linux/perf/arm_pmu.h
@@ -187,5 +187,6 @@ void armpmu_free_irq(int irq, int cpu);
#endif /* CONFIG_ARM_PMU */

#define ARMV8_SPE_PDEV_NAME "arm,spe-v1"
+#define ARMV8_TRBE_PDEV_NAME "arm,trbe"

#endif /* __ARM_PMU_H__ */
--
2.25.1