arch/sh/drivers/heartbeat.c

   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
  28 #define DRV_NAME "heartbeat"
  29 #define DRV_VERSION "0.1.0"
  30
  31 struct heartbeat_data {
  32         void __iomem *base;
  33         unsigned char bit_pos[8];
  34         struct timer_list timer;
  35 };
  36
  37 static void heartbeat_timer(unsigned long data)
  38 {
  39         struct heartbeat_data *hd = (struct heartbeat_data *)data;
  40         static unsigned bit = 0, up = 1;
  41
  42         ctrl_outw(1 << hd->bit_pos[bit], (unsigned long)hd->base);
  43         if (up)
  44                 if (bit == (ARRAY_SIZE(hd->bit_pos) - 1)) {
  45                         bit--;
  46                         up = 0;
  47                 } else
  48                         bit++;
  49         else if (bit == 0)
  50                 up = 1;
  51         else
  52                 bit--;
  53
  54         mod_timer(&hd->timer, jiffies + (110 - ((300 << FSHIFT) /
  55                         ((avenrun[0] / 5) + (3 << FSHIFT)))));
  56 }
  57
  58 static int heartbeat_drv_probe(struct platform_device *pdev)
  59 {
  60         struct resource *res;
  61         struct heartbeat_data *hd;
  62
  63         if (unlikely(pdev->num_resources != 1)) {
  64                 dev_err(&pdev->dev, "invalid number of resources\n");
  65                 return -EINVAL;
  66         }
  67
  68         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  69         if (unlikely(res == NULL)) {
  70                 dev_err(&pdev->dev, "invalid resource\n");
  71                 return -EINVAL;
  72         }
  73
  74         hd = kmalloc(sizeof(struct heartbeat_data), GFP_KERNEL);
  75         if (unlikely(!hd))
  76                 return -ENOMEM;
  77
  78         if (pdev->dev.platform_data) {
  79                 memcpy(hd->bit_pos, pdev->dev.platform_data,
  80                        ARRAY_SIZE(hd->bit_pos));
  81         } else {
  82                 int i;
  83
  84                 for (i = 0; i < ARRAY_SIZE(hd->bit_pos); i++)
  85                         hd->bit_pos[i] = i;
  86         }
  87
  88         hd->base = (void __iomem *)res->start;
  89
  90         setup_timer(&hd->timer, heartbeat_timer, (unsigned long)hd);
  91         platform_set_drvdata(pdev, hd);
  92
  93         return mod_timer(&hd->timer, jiffies + 1);
  94 }
  95
  96 static int heartbeat_drv_remove(struct platform_device *pdev)
  97 {
  98         struct heartbeat_data *hd = platform_get_drvdata(pdev);
  99
 100         del_timer_sync(&hd->timer);
 101
 102         platform_set_drvdata(pdev, NULL);
 103
 104         kfree(hd);
 105
 106         return 0;
 107 }
 108
 109 static struct platform_driver heartbeat_driver = {
 110         .probe          = heartbeat_drv_probe,
 111         .remove         = heartbeat_drv_remove,
 112         .driver         = {
 113                 .name   = DRV_NAME,
 114         },
 115 };
 116
 117 static int __init heartbeat_init(void)
 118 {
 119         printk(KERN_NOTICE DRV_NAME ": version %s loaded\n", DRV_VERSION);
 120         return platform_driver_register(&heartbeat_driver);
 121 }
 122
 123 static void __exit heartbeat_exit(void)
 124 {
 125         platform_driver_unregister(&heartbeat_driver);
 126 }
 127 module_init(heartbeat_init);
 128 module_exit(heartbeat_exit);
 129
 130 MODULE_VERSION(DRV_VERSION);
 131 MODULE_AUTHOR("Paul Mundt");
 132 MODULE_LICENSE("GPLv2");