/arch/arm/kernel/pmu.c

  1/*
  2 *  linux/arch/arm/kernel/pmu.c
  3 *
  4 *  Copyright (C) 2009 picoChip Designs Ltd, Jamie Iles
  5 *  Copyright (C) 2010 ARM Ltd, Will Deacon
  6 *
  7 * This program is free software; you can redistribute it and/or modify
  8 * it under the terms of the GNU General Public License version 2 as
  9 * published by the Free Software Foundation.
 10 *
 11 */
 12
 13#define pr_fmt(fmt) "PMU: " fmt
 14
 15#include <linux/cpumask.h>
 16#include <linux/err.h>
 17#include <linux/interrupt.h>
 18#include <linux/kernel.h>
 19#include <linux/module.h>
 20#include <linux/platform_device.h>
 21
 22#include <asm/pmu.h>
 23
 24static volatile long pmu_lock;
 25
 26static struct platform_device *pmu_devices[ARM_NUM_PMU_DEVICES];
 27
 28static int __devinit pmu_device_probe(struct platform_device *pdev)
 29{
 30
 31	if (pdev->id < 0 || pdev->id >= ARM_NUM_PMU_DEVICES) {
 32		pr_warning("received registration request for unknown "
 33				"device %d\n", pdev->id);
 34		return -EINVAL;
 35	}
 36
 37	if (pmu_devices[pdev->id])
 38		pr_warning("registering new PMU device type %d overwrites "
 39				"previous registration!\n", pdev->id);
 40	else
 41		pr_info("registered new PMU device of type %d\n",
 42				pdev->id);
 43
 44	pmu_devices[pdev->id] = pdev;
 45	return 0;
 46}
 47
 48static struct platform_driver pmu_driver = {
 49	.driver		= {
 50		.name	= "arm-pmu",
 51	},
 52	.probe		= pmu_device_probe,
 53};
 54
 55static int __init register_pmu_driver(void)
 56{
 57	return platform_driver_register(&pmu_driver);
 58}
 59device_initcall(register_pmu_driver);
 60
 61struct platform_device *
 62reserve_pmu(enum arm_pmu_type device)
 63{
 64	struct platform_device *pdev;
 65
 66	if (test_and_set_bit_lock(device, &pmu_lock)) {
 67		pdev = ERR_PTR(-EBUSY);
 68	} else if (pmu_devices[device] == NULL) {
 69		clear_bit_unlock(device, &pmu_lock);
 70		pdev = ERR_PTR(-ENODEV);
 71	} else {
 72		pdev = pmu_devices[device];
 73	}
 74
 75	return pdev;
 76}
 77EXPORT_SYMBOL_GPL(reserve_pmu);
 78
 79int
 80release_pmu(struct platform_device *pdev)
 81{
 82	if (WARN_ON(pdev != pmu_devices[pdev->id]))
 83		return -EINVAL;
 84	clear_bit_unlock(pdev->id, &pmu_lock);
 85	return 0;
 86}
 87EXPORT_SYMBOL_GPL(release_pmu);
 88
 89static int
 90set_irq_affinity(int irq,
 91		 unsigned int cpu)
 92{
 93#ifdef CONFIG_SMP
 94	int err = irq_set_affinity(irq, cpumask_of(cpu));
 95	if (err)
 96		pr_warning("unable to set irq affinity (irq=%d, cpu=%u)\n",
 97			   irq, cpu);
 98	return err;
 99#else
100	return 0;
101#endif
102}
103
104static int
105init_cpu_pmu(void)
106{
107	int i, err = 0;
108	struct platform_device *pdev = pmu_devices[ARM_PMU_DEVICE_CPU];
109
110	if (!pdev) {
111		err = -ENODEV;
112		goto out;
113	}
114
115	for (i = 0; i < pdev->num_resources; ++i) {
116		err = set_irq_affinity(platform_get_irq(pdev, i), i);
117		if (err)
118			break;
119	}
120
121out:
122	return err;
123}
124
125int
126init_pmu(enum arm_pmu_type device)
127{
128	int err = 0;
129
130	switch (device) {
131	case ARM_PMU_DEVICE_CPU:
132		err = init_cpu_pmu();
133		break;
134	default:
135		pr_warning("attempt to initialise unknown device %d\n",
136				device);
137		err = -EINVAL;
138	}
139
140	return err;
141}
142EXPORT_SYMBOL_GPL(init_pmu);