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 #include <asm/heartbeat.h>
  28
  29 #define DRV_NAME "heartbeat"
  30 #define DRV_VERSION "0.1.1"
  31
  32 static unsigned char default_bit_pos[] = { 0, 1, 2, 3, 4, 5, 6, 7 };
  33
  34 static 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
  56 static 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
  71 static 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
 119 static 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
 134 static struct platform_driver heartbeat_driver = {
 135         .probe          = heartbeat_drv_probe,
 136         .remove         = heartbeat_drv_remove,
 137         .driver         = {
 138                 .name   = DRV_NAME,
 139         },
 140 };
 141
 142 static 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
 148 static void __exit heartbeat_exit(void)
 149 {
 150         platform_driver_unregister(&heartbeat_driver);
 151 }
 152 module_init(heartbeat_init);
 153 module_exit(heartbeat_exit);
 154
 155 MODULE_VERSION(DRV_VERSION);
 156 MODULE_AUTHOR("Paul Mundt");
 157 MODULE_LICENSE("GPLv2");