heartbeat.c

Go to the documentation of this file.

/*
 * Generic heartbeat driver for regular LED banks
 *
 * Copyright (C) 2007 - 2010  Paul Mundt
 *
 * Most SH reference boards include a number of individual LEDs that can
 * be independently controlled (either via a pre-defined hardware
 * function or via the LED class, if desired -- the hardware tends to
 * encapsulate some of the same "triggers" that the LED class supports,
 * so there's not too much value in it).
 *
 * Additionally, most of these boards also have a LED bank that we've
 * traditionally used for strobing the load average. This use case is
 * handled by this driver, rather than giving each LED bit position its
 * own struct device.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <asm/heartbeat.h>

#define DRV_NAME "heartbeat"
#define DRV_VERSION "0.1.2"

static unsigned char default_bit_pos[] = { 0, 1, 2, 3, 4, 5, 6, 7 };

static inline void heartbeat_toggle_bit(struct heartbeat_data *hd,
                    unsigned bit, unsigned int inverted)
{
    unsigned int new;

    new = (1 << hd->bit_pos[bit]);
    if (inverted)
        new = ~new;

    new &= hd->mask;

    switch (hd->regsize) {
    case 32:
        new |= ioread32(hd->base) & ~hd->mask;
        iowrite32(new, hd->base);
        break;
    case 16:
        new |= ioread16(hd->base) & ~hd->mask;
        iowrite16(new, hd->base);
        break;
    default:
        new |= ioread8(hd->base) & ~hd->mask;
        iowrite8(new, hd->base);
        break;
    }
}

static void heartbeat_timer(unsigned long data)
{
    struct heartbeat_data *hd = (struct heartbeat_data *)data;
    static unsigned bit = 0, up = 1;

    heartbeat_toggle_bit(hd, bit, hd->flags & HEARTBEAT_INVERTED);

    bit += up;
    if ((bit == 0) || (bit == (hd->nr_bits)-1))
        up = -up;

    mod_timer(&hd->timer, jiffies + (110 - ((300 << FSHIFT) /
            ((avenrun[0] / 5) + (3 << FSHIFT)))));
}

static int heartbeat_drv_probe(struct platform_device *pdev)
{
    struct resource *res;
    struct heartbeat_data *hd;
    int i;

    if (unlikely(pdev->num_resources != 1)) {
        dev_err(&pdev->dev, "invalid number of resources\n");
        return -EINVAL;
    }

    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (unlikely(res == NULL)) {
        dev_err(&pdev->dev, "invalid resource\n");
        return -EINVAL;
    }

    if (pdev->dev.platform_data) {
        hd = pdev->dev.platform_data;
    } else {
        hd = kzalloc(sizeof(struct heartbeat_data), GFP_KERNEL);
        if (unlikely(!hd))
            return -ENOMEM;
    }

    hd->base = ioremap_nocache(res->start, resource_size(res));
    if (unlikely(!hd->base)) {
        dev_err(&pdev->dev, "ioremap failed\n");

        if (!pdev->dev.platform_data)
            kfree(hd);

        return -ENXIO;
    }

    if (!hd->nr_bits) {
        hd->bit_pos = default_bit_pos;
        hd->nr_bits = ARRAY_SIZE(default_bit_pos);
    }

    hd->mask = 0;
    for (i = 0; i < hd->nr_bits; i++)
        hd->mask |= (1 << hd->bit_pos[i]);

    if (!hd->regsize) {
        switch (res->flags & IORESOURCE_MEM_TYPE_MASK) {
        case IORESOURCE_MEM_32BIT:
            hd->regsize = 32;
            break;
        case IORESOURCE_MEM_16BIT:
            hd->regsize = 16;
            break;
        case IORESOURCE_MEM_8BIT:
        default:
            hd->regsize = 8;
            break;
        }
    }

    setup_timer(&hd->timer, heartbeat_timer, (unsigned long)hd);
    platform_set_drvdata(pdev, hd);

    return mod_timer(&hd->timer, jiffies + 1);
}

static int heartbeat_drv_remove(struct platform_device *pdev)
{
    struct heartbeat_data *hd = platform_get_drvdata(pdev);

    del_timer_sync(&hd->timer);
    iounmap(hd->base);

    platform_set_drvdata(pdev, NULL);

    if (!pdev->dev.platform_data)
        kfree(hd);

    return 0;
}

static struct platform_driver heartbeat_driver = {
    .probe      = heartbeat_drv_probe,
    .remove     = heartbeat_drv_remove,
    .driver     = {
        .name   = DRV_NAME,
    },
};

static int __init heartbeat_init(void)
{
    printk(KERN_NOTICE DRV_NAME ": version %s loaded\n", DRV_VERSION);
    return platform_driver_register(&heartbeat_driver);
}

static void __exit heartbeat_exit(void)
{
    platform_driver_unregister(&heartbeat_driver);
}
module_init(heartbeat_init);
module_exit(heartbeat_exit);

MODULE_VERSION(DRV_VERSION);
MODULE_AUTHOR("Paul Mundt");
MODULE_LICENSE("GPL v2");