ARM: 6064/1: pmu: register IRQs at runtime
authorWill Deacon <will.deacon@arm.com>
Thu, 29 Apr 2010 16:13:24 +0000 (17:13 +0100)
committerRussell King <rmk+kernel@arm.linux.org.uk>
Mon, 17 May 2010 10:53:57 +0000 (11:53 +0100)
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>
arch/arm/include/asm/pmu.h
arch/arm/kernel/perf_event.c
arch/arm/kernel/pmu.c

index 44bec1f..8ccea01 100644 (file)
@@ -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;
 }
index 9e70f20..89a77fc 100644 (file)
@@ -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);
index a124312..b8af96e 100644 (file)
@@ -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
  *
  */
 
+#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);