linux/arch/sh/drivers/heartbeat.c
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   1/*
   2 * Generic heartbeat driver for regular LED banks
   3 *
   4 * Copyright (C) 2007  Paul Mundt
   5 *
   6 * Most SH reference boards include a number of individual LEDs that can
   7 * be independently controlled (either via a pre-defined hardware
   8 * function or via the LED class, if desired -- the hardware tends to
   9 * encapsulate some of the same "triggers" that the LED class supports,
  10 * so there's not too much value in it).
  11 *
  12 * Additionally, most of these boards also have a LED bank that we've
  13 * traditionally used for strobing the load average. This use case is
  14 * handled by this driver, rather than giving each LED bit position its
  15 * own struct device.
  16 *
  17 * This file is subject to the terms and conditions of the GNU General Public
  18 * License.  See the file "COPYING" in the main directory of this archive
  19 * for more details.
  20 */
  21#include <linux/init.h>
  22#include <linux/module.h>
  23#include <linux/platform_device.h>
  24#include <linux/sched.h>
  25#include <linux/timer.h>
  26#include <linux/io.h>
  27#include <asm/heartbeat.h>
  28
  29#define DRV_NAME "heartbeat"
  30#define DRV_VERSION "0.1.1"
  31
  32static unsigned char default_bit_pos[] = { 0, 1, 2, 3, 4, 5, 6, 7 };
  33
  34static inline void heartbeat_toggle_bit(struct heartbeat_data *hd,
  35                                        unsigned bit, unsigned int inverted)
  36{
  37        unsigned int new;
  38
  39        new = (1 << hd->bit_pos[bit]);
  40        if (inverted)
  41                new = ~new;
  42
  43        switch (hd->regsize) {
  44        case 32:
  45                iowrite32(new, hd->base);
  46                break;
  47        case 16:
  48                iowrite16(new, hd->base);
  49                break;
  50        default:
  51                iowrite8(new, hd->base);
  52                break;
  53        }
  54}
  55
  56static void heartbeat_timer(unsigned long data)
  57{
  58        struct heartbeat_data *hd = (struct heartbeat_data *)data;
  59        static unsigned bit = 0, up = 1;
  60
  61        heartbeat_toggle_bit(hd, bit, hd->flags & HEARTBEAT_INVERTED);
  62
  63        bit += up;
  64        if ((bit == 0) || (bit == (hd->nr_bits)-1))
  65                up = -up;
  66
  67        mod_timer(&hd->timer, jiffies + (110 - ((300 << FSHIFT) /
  68                        ((avenrun[0] / 5) + (3 << FSHIFT)))));
  69}
  70
  71static int heartbeat_drv_probe(struct platform_device *pdev)
  72{
  73        struct resource *res;
  74        struct heartbeat_data *hd;
  75
  76        if (unlikely(pdev->num_resources != 1)) {
  77                dev_err(&pdev->dev, "invalid number of resources\n");
  78                return -EINVAL;
  79        }
  80
  81        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  82        if (unlikely(res == NULL)) {
  83                dev_err(&pdev->dev, "invalid resource\n");
  84                return -EINVAL;
  85        }
  86
  87        if (pdev->dev.platform_data) {
  88                hd = pdev->dev.platform_data;
  89        } else {
  90                hd = kzalloc(sizeof(struct heartbeat_data), GFP_KERNEL);
  91                if (unlikely(!hd))
  92                        return -ENOMEM;
  93        }
  94
  95        hd->base = ioremap_nocache(res->start, res->end - res->start + 1);
  96        if (unlikely(!hd->base)) {
  97                dev_err(&pdev->dev, "ioremap failed\n");
  98
  99                if (!pdev->dev.platform_data)
 100                        kfree(hd);
 101
 102                return -ENXIO;
 103        }
 104
 105        if (!hd->nr_bits) {
 106                hd->bit_pos = default_bit_pos;
 107                hd->nr_bits = ARRAY_SIZE(default_bit_pos);
 108        }
 109
 110        if (!hd->regsize)
 111                hd->regsize = 8;        /* default access size */
 112
 113        setup_timer(&hd->timer, heartbeat_timer, (unsigned long)hd);
 114        platform_set_drvdata(pdev, hd);
 115
 116        return mod_timer(&hd->timer, jiffies + 1);
 117}
 118
 119static int heartbeat_drv_remove(struct platform_device *pdev)
 120{
 121        struct heartbeat_data *hd = platform_get_drvdata(pdev);
 122
 123        del_timer_sync(&hd->timer);
 124        iounmap(hd->base);
 125
 126        platform_set_drvdata(pdev, NULL);
 127
 128        if (!pdev->dev.platform_data)
 129                kfree(hd);
 130
 131        return 0;
 132}
 133
 134static struct platform_driver heartbeat_driver = {
 135        .probe          = heartbeat_drv_probe,
 136        .remove         = heartbeat_drv_remove,
 137        .driver         = {
 138                .name   = DRV_NAME,
 139        },
 140};
 141
 142static int __init heartbeat_init(void)
 143{
 144        printk(KERN_NOTICE DRV_NAME ": version %s loaded\n", DRV_VERSION);
 145        return platform_driver_register(&heartbeat_driver);
 146}
 147
 148static void __exit heartbeat_exit(void)
 149{
 150        platform_driver_unregister(&heartbeat_driver);
 151}
 152module_init(heartbeat_init);
 153module_exit(heartbeat_exit);
 154
 155MODULE_VERSION(DRV_VERSION);
 156MODULE_AUTHOR("Paul Mundt");
 157MODULE_LICENSE("GPL v2");
 158