ARM: 6064/1: pmu: register IRQs at runtime

The current PMU infrastructure for ARM requires that the IRQs for the PMU
device are fixed at compile time and are selected based on the ARCH_ or MACH_ flags. This has the disadvantage of tying the Kernel down to a
particular board as far as profiling is concerned.

This patch replaces the compile-time IRQ registration with a runtime mechanism which allows the IRQs to be registered with the framework as
a platform_device.

A further advantage of this change is that there is scope for registering
different types of performance counters in the future by changing the id
of the platform_device and attaching different resources to it.

Acked-by: Jamie Iles <jamie.iles@picochip.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 126 insertions, 80 deletions

diff --git a/arch/arm/include/asm/pmu.h b/arch/arm/include/asm/pmu.h
index 44bec1f02cb0..8ccea012722c 100644
--- a/arch/arm/include/asm/pmu.h
+++ b/arch/arm/include/asm/pmu.h
@@ -19,31 +19,26 @@ enum arm_pmu_type {
 
 #ifdef CONFIG_CPU_HAS_PMU
 
-struct pmu_irqs {
-        const int   *irqs;
-        int         num_irqs;
-};
-
 /**
  * reserve_pmu() - reserve the hardware performance counters
  *
  * Reserve the hardware performance counters in the system for exclusive use.
- * The 'struct pmu_irqs' for the system is returned on success, ERR_PTR()
+ * The platform_device for the system is returned on success, ERR_PTR()
  * encoded error on failure.
  */
-extern const struct pmu_irqs *
-reserve_pmu(void);
+extern struct platform_device *
+reserve_pmu(enum arm_pmu_type device);
 
 /**
  * release_pmu() - Relinquish control of the performance counters
  *
  * Release the performance counters and allow someone else to use them.
  * Callers must have disabled the counters and released IRQs before calling
- * this. The 'struct pmu_irqs' returned from reserve_pmu() must be passed as
+ * this. The platform_device returned from reserve_pmu() must be passed as
  * a cookie.
  */
 extern int
-release_pmu(const struct pmu_irqs *irqs);
+release_pmu(struct platform_device *pdev);
 
 /**
  * init_pmu() - Initialise the PMU.
@@ -53,24 +48,26 @@ release_pmu(const struct pmu_irqs *irqs);
  * the actual hardware initialisation.
  */
 extern int
-init_pmu(void);
+init_pmu(enum arm_pmu_type device);
 
 #else /* CONFIG_CPU_HAS_PMU */
 
-static inline const struct pmu_irqs *
-reserve_pmu(void)
+#include <linux/err.h>
+
+static inline struct platform_device *
+reserve_pmu(enum arm_pmu_type device)
 {
         return ERR_PTR(-ENODEV);
 }
 
 static inline int
-release_pmu(const struct pmu_irqs *irqs)
+release_pmu(struct platform_device *pdev)
 {
         return -ENODEV;
 }
 
 static inline int
-init_pmu(void)
+init_pmu(enum arm_pmu_type device)
 {
         return -ENODEV;
 }
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 9e70f2053f9a..89a77fcb13e3 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -17,6 +17,7 @@
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <linux/perf_event.h>
+#include <linux/platform_device.h>
 #include <linux/spinlock.h>
 #include <linux/uaccess.h>
 
@@ -26,7 +27,7 @@
 #include <asm/pmu.h>
 #include <asm/stacktrace.h>
 
-static const struct pmu_irqs *pmu_irqs;
+static struct platform_device *pmu_device;
 
 /*
  * Hardware lock to serialize accesses to PMU registers. Needed for the
@@ -314,38 +315,44 @@ validate_group(struct perf_event *event)
 static int
 armpmu_reserve_hardware(void)
 {
-        int i;
-        int err;
+        int i, err = -ENODEV, irq;
 
-        pmu_irqs = reserve_pmu();
-        if (IS_ERR(pmu_irqs)) {
+        pmu_device = reserve_pmu(ARM_PMU_DEVICE_CPU);
+        if (IS_ERR(pmu_device)) {
                 pr_warning("unable to reserve pmu\n");
-                return PTR_ERR(pmu_irqs);
+                return PTR_ERR(pmu_device);
         }
 
-        init_pmu();
+        init_pmu(ARM_PMU_DEVICE_CPU);
 
-        if (pmu_irqs->num_irqs < 1) {
+        if (pmu_device->num_resources < 1) {
                 pr_err("no irqs for PMUs defined\n");
                 return -ENODEV;
         }
 
-        for (i = 0; i < pmu_irqs->num_irqs; ++i) {
-                err = request_irq(pmu_irqs->irqs[i], armpmu->handle_irq,
+        for (i = 0; i < pmu_device->num_resources; ++i) {
+                irq = platform_get_irq(pmu_device, i);
+                if (irq < 0)
+                        continue;
+
+                err = request_irq(irq, armpmu->handle_irq,
                                   IRQF_DISABLED | IRQF_NOBALANCING,
                                   "armpmu", NULL);
                 if (err) {
-                        pr_warning("unable to request IRQ%d for ARM "
-                                   "perf counters\n", pmu_irqs->irqs[i]);
+                        pr_warning("unable to request IRQ%d for ARM perf "
+                                "counters\n", irq);
                         break;
                 }
         }
 
         if (err) {
-                for (i = i - 1; i >= 0; --i)
-                        free_irq(pmu_irqs->irqs[i], NULL);
-                release_pmu(pmu_irqs);
-                pmu_irqs = NULL;
+                for (i = i - 1; i >= 0; --i) {
+                        irq = platform_get_irq(pmu_device, i);
+                        if (irq >= 0)
+                                free_irq(irq, NULL);
+                }
+                release_pmu(pmu_device);
+                pmu_device = NULL;
         }
 
         return err;
@@ -354,14 +361,17 @@ armpmu_reserve_hardware(void)
 static void
 armpmu_release_hardware(void)
 {
-        int i;
+        int i, irq;
 
-        for (i = pmu_irqs->num_irqs - 1; i >= 0; --i)
-                free_irq(pmu_irqs->irqs[i], NULL);
+        for (i = pmu_device->num_resources - 1; i >= 0; --i) {
+                irq = platform_get_irq(pmu_device, i);
+                if (irq >= 0)
+                        free_irq(irq, NULL);
+        }
         armpmu->stop();
 
-        release_pmu(pmu_irqs);
-        pmu_irqs = NULL;
+        release_pmu(pmu_device);
+        pmu_device = NULL;
 }
 
 static atomic_t active_events = ATOMIC_INIT(0);
diff --git a/arch/arm/kernel/pmu.c b/arch/arm/kernel/pmu.c
index a124312e343f..b8af96ea62e6 100644
--- a/arch/arm/kernel/pmu.c
+++ b/arch/arm/kernel/pmu.c
@@ -2,6 +2,7 @@
  *  linux/arch/arm/kernel/pmu.c
  *
  *  Copyright (C) 2009 picoChip Designs Ltd, Jamie Iles
+ *  Copyright (C) 2010 ARM Ltd, Will Deacon
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -9,65 +10,78 @@
  *
  */
 
+#define pr_fmt(fmt) "PMU: " fmt
+
 #include <linux/cpumask.h>
 #include <linux/err.h>
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/platform_device.h>
 
 #include <asm/pmu.h>
 
-/*
- * Define the IRQs for the system. We could use something like a platform
- * device but that seems fairly heavyweight for this. Also, the performance
- * counters can't be removed or hotplugged.
- *
- * Ordering is important: init_pmu() will use the ordering to set the affinity
- * to the corresponding core. e.g. the first interrupt will go to cpu 0, the
- * second goes to cpu 1 etc.
- */
-static const int irqs[] = {
-#if defined(CONFIG_ARCH_OMAP2)
-        3,
-#elif defined(CONFIG_ARCH_BCMRING)
-        IRQ_PMUIRQ,
-#elif defined(CONFIG_MACH_REALVIEW_EB)
-        IRQ_EB11MP_PMU_CPU0,
-        IRQ_EB11MP_PMU_CPU1,
-        IRQ_EB11MP_PMU_CPU2,
-        IRQ_EB11MP_PMU_CPU3,
-#elif defined(CONFIG_ARCH_OMAP3)
-        INT_34XX_BENCH_MPU_EMUL,
-#elif defined(CONFIG_ARCH_IOP32X)
-        IRQ_IOP32X_CORE_PMU,
-#elif defined(CONFIG_ARCH_IOP33X)
-        IRQ_IOP33X_CORE_PMU,
-#elif defined(CONFIG_ARCH_PXA)
-        IRQ_PMU,
-#endif
-};
+static volatile long pmu_lock;
+
+static struct platform_device *pmu_devices[ARM_NUM_PMU_DEVICES];
+
+static int __devinit pmu_device_probe(struct platform_device *pdev)
+{
+
+        if (pdev->id < 0 || pdev->id >= ARM_NUM_PMU_DEVICES) {
+                pr_warning("received registration request for unknown "
+                                "device %d\n", pdev->id);
+                return -EINVAL;
+        }
+
+        if (pmu_devices[pdev->id])
+                pr_warning("registering new PMU device type %d overwrites "
+                                "previous registration!\n", pdev->id);
+        else
+                pr_info("registered new PMU device of type %d\n",
+                                pdev->id);
 
-static const struct pmu_irqs pmu_irqs = {
-        .irqs       = irqs,
-        .num_irqs   = ARRAY_SIZE(irqs),
+        pmu_devices[pdev->id] = pdev;
+        return 0;
+}
+
+static struct platform_driver pmu_driver = {
+        .driver         = {
+                .name   = "arm-pmu",
+        },
+        .probe          = pmu_device_probe,
 };
 
-static volatile long pmu_lock;
+static int __init register_pmu_driver(void)
+{
+        return platform_driver_register(&pmu_driver);
+}
+device_initcall(register_pmu_driver);
 
-const struct pmu_irqs *
-reserve_pmu(void)
+struct platform_device *
+reserve_pmu(enum arm_pmu_type device)
 {
-        return test_and_set_bit_lock(0, &pmu_lock) ? ERR_PTR(-EBUSY) :
-                &pmu_irqs;
+        struct platform_device *pdev;
+
+        if (test_and_set_bit_lock(device, &pmu_lock)) {
+                pdev = ERR_PTR(-EBUSY);
+        } else if (pmu_devices[device] == NULL) {
+                clear_bit_unlock(device, &pmu_lock);
+                pdev = ERR_PTR(-ENODEV);
+        } else {
+                pdev = pmu_devices[device];
+        }
+
+        return pdev;
 }
 EXPORT_SYMBOL_GPL(reserve_pmu);
 
 int
-release_pmu(const struct pmu_irqs *irqs)
+release_pmu(struct platform_device *pdev)
 {
-        if (WARN_ON(irqs != &pmu_irqs))
+        if (WARN_ON(pdev != pmu_devices[pdev->id]))
                 return -EINVAL;
-        clear_bit_unlock(0, &pmu_lock);
+        clear_bit_unlock(pdev->id, &pmu_lock);
         return 0;
 }
 EXPORT_SYMBOL_GPL(release_pmu);
@@ -87,17 +101,42 @@ set_irq_affinity(int irq,
 #endif
 }
 
-int
-init_pmu(void)
+static int
+init_cpu_pmu(void)
 {
         int i, err = 0;
+        struct platform_device *pdev = pmu_devices[ARM_PMU_DEVICE_CPU];
+
+        if (!pdev) {
+                err = -ENODEV;
+                goto out;
+        }
 
-        for (i = 0; i < pmu_irqs.num_irqs; ++i) {
-                err = set_irq_affinity(pmu_irqs.irqs[i], i);
+        for (i = 0; i < pdev->num_resources; ++i) {
+                err = set_irq_affinity(platform_get_irq(pdev, i), i);
                 if (err)
                         break;
         }
 
+out:
+        return err;
+}
+
+int
+init_pmu(enum arm_pmu_type device)
+{
+        int err = 0;
+
+        switch (device) {
+        case ARM_PMU_DEVICE_CPU:
+                err = init_cpu_pmu();
+                break;
+        default:
+                pr_warning("attempt to initialise unknown device %d\n",
+                                device);
+                err = -EINVAL;
+        }
+
         return err;
 }
 EXPORT_SYMBOL_GPL(init_pmu);