[PATCH 3/8] arm64: pmu: Add support for probing with ACPI

[Jeremy Linton]

From: Mark Salter <msalter at redhat.com>

In the case of ACPI, the PMU IRQ information is contained in the
MADT table. Also, since the PMU does not exist as a device in the
ACPI DSDT table, it is necessary to create a platform device so
that the appropriate driver probing is triggered.

Signed-off-by: Mark Salter <msalter at redhat.com>
Signed-off-by: Jeremy Linton <jeremy.linton at arm.com>
---

 NOTE: Much of the code in pmu_acpi_init() is replaced in a later version
       of this patch. The later version of the patch cleans up some of the
       possible style/error handling issues that have been pointed out with
       this version.

 arch/arm64/kernel/smp.c      |  5 +++
 drivers/perf/Kconfig         |  4 ++
 drivers/perf/Makefile        |  1 +
 drivers/perf/arm_pmu_acpi.c  | 97 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/perf/arm_pmu.h |  7 ++++
 5 files changed, 114 insertions(+)
 create mode 100644 drivers/perf/arm_pmu_acpi.c

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 678e084..5c96d23 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -37,6 +37,7 @@
 #include <linux/completion.h>
 #include <linux/of.h>
 #include <linux/irq_work.h>
+#include <linux/perf/arm_pmu.h>
 
 #include <asm/alternative.h>
 #include <asm/atomic.h>
@@ -540,6 +541,7 @@ acpi_map_gic_cpu_interface(struct acpi_madt_generic_interrupt *processor)
 			return;
 		}
 		bootcpu_valid = true;
+		arm_pmu_parse_acpi(0, processor);
 		return;
 	}
 
@@ -560,6 +562,9 @@ acpi_map_gic_cpu_interface(struct acpi_madt_generic_interrupt *processor)
 	 */
 	acpi_set_mailbox_entry(cpu_count, processor);
 
+	/* get PMU irq info */
+	arm_pmu_parse_acpi(cpu_count, processor);
+
 	cpu_count++;
 }
 
diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
index 04e2653..818fa3b 100644
--- a/drivers/perf/Kconfig
+++ b/drivers/perf/Kconfig
@@ -12,4 +12,8 @@ config ARM_PMU
 	  Say y if you want to use CPU performance monitors on ARM-based
 	  systems.
 
+config ARM_PMU_ACPI
+	def_bool y
+	depends on ARM_PMU && ACPI
+
 endmenu
diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
index acd2397..fd8090d 100644
--- a/drivers/perf/Makefile
+++ b/drivers/perf/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_ARM_PMU) += arm_pmu.o
+obj-$(CONFIG_ARM_PMU_ACPI) += arm_pmu_acpi.o
diff --git a/drivers/perf/arm_pmu_acpi.c b/drivers/perf/arm_pmu_acpi.c
new file mode 100644
index 0000000..98c452d
--- /dev/null
+++ b/drivers/perf/arm_pmu_acpi.c
@@ -0,0 +1,97 @@
+/*
+ * PMU support
+ *
+ * Copyright (C) 2015 Red Hat Inc.
+ * Author: Mark Salter <msalter at redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include <linux/perf/arm_pmu.h>
+#include <linux/platform_device.h>
+#include <linux/acpi.h>
+#include <linux/irq.h>
+#include <linux/irqdesc.h>
+
+#define PMU_PDEV_NAME "armv8-pmu"
+
+struct pmu_irq {
+	int gsi;
+	int trigger;
+};
+
+static struct pmu_irq pmu_irqs[NR_CPUS] __initdata;
+
+void __init arm_pmu_parse_acpi(int cpu, struct acpi_madt_generic_interrupt *gic)
+{
+	pmu_irqs[cpu].gsi = gic->performance_interrupt;
+	if (gic->flags & ACPI_MADT_PERFORMANCE_IRQ_MODE)
+		pmu_irqs[cpu].trigger = ACPI_EDGE_SENSITIVE;
+	else
+		pmu_irqs[cpu].trigger = ACPI_LEVEL_SENSITIVE;
+}
+
+static int __init pmu_acpi_init(void)
+{
+	struct platform_device *pdev;
+	struct pmu_irq *pirq = pmu_irqs;
+	struct resource	*res, *r;
+	int err = -ENOMEM;
+	int i, count, irq;
+
+	if (acpi_disabled)
+		return 0;
+
+	/* Must have irq for boot boot cpu, at least */
+	if (pirq->gsi == 0)
+		return -EINVAL;
+
+	irq = acpi_register_gsi(NULL, pirq->gsi, pirq->trigger,
+				ACPI_ACTIVE_HIGH);
+
+	if (irq_is_percpu(irq))
+		count = 1;
+	else
+		for (i = 1, count = 1; i < NR_CPUS; i++)
+			if (pmu_irqs[i].gsi)
+				++count;
+
+	pdev = platform_device_alloc(PMU_PDEV_NAME, -1);
+	if (!pdev)
+		goto err_free_gsi;
+
+	res = kcalloc(count, sizeof(*res), GFP_KERNEL);
+	if (!res)
+		goto err_free_device;
+
+	for (i = 0, r = res; i < count; i++, pirq++, r++) {
+		if (i)
+			irq = acpi_register_gsi(NULL, pirq->gsi, pirq->trigger,
+						ACPI_ACTIVE_HIGH);
+		r->start = r->end = irq;
+		r->flags = IORESOURCE_IRQ;
+		if (pirq->trigger == ACPI_EDGE_SENSITIVE)
+			r->flags |= IORESOURCE_IRQ_HIGHEDGE;
+		else
+			r->flags |= IORESOURCE_IRQ_HIGHLEVEL;
+	}
+
+	err = platform_device_add_resources(pdev, res, count);
+	if (!err)
+		err = platform_device_add(pdev);
+	kfree(res);
+	if (!err)
+		return 0;
+
+err_free_device:
+	platform_device_put(pdev);
+
+err_free_gsi:
+	for (i = 0; i < count; i++)
+		acpi_unregister_gsi(pmu_irqs[i].gsi);
+
+	return err;
+}
+arch_initcall(pmu_acpi_init);
diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
index 7e814fe..9ed9fdc 100644
--- a/include/linux/perf/arm_pmu.h
+++ b/include/linux/perf/arm_pmu.h
@@ -156,4 +156,11 @@ int arm_pmu_device_probe(struct platform_device *pdev,
 
 #endif /* CONFIG_ARM_PMU */
 
+#ifdef CONFIG_ARM_PMU_ACPI
+struct acpi_madt_generic_interrupt;
+void arm_pmu_parse_acpi(int cpu, struct acpi_madt_generic_interrupt *gic);
+#else
+#define arm_pmu_parse_acpi(a, b) do { } while (0)
+#endif /* CONFIG_ARM_PMU_ACPI */
+
 #endif /* __ARM_PMU_H__ */
-- 
2.5.5