drivers/watchdog/m548x_wdt.c

   1 /*
   2  * drivers/watchdog/m548x_wdt.c
   3  *
   4  * Watchdog driver for ColdFire MCF548x processors
   5  * Copyright 2010 (c) Philippe De Muyter <phdm@macqel.be>
   6  *
   7  * Adapted from the IXP4xx watchdog driver, which carries these notices:
   8  *
   9  *  Author: Deepak Saxena <dsaxena@plexity.net>
  10  *
  11  *  Copyright 2004 (c) MontaVista, Software, Inc.
  12  *  Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
  13  *
  14  * This file is licensed under  the terms of the GNU General Public
  15  * License version 2. This program is licensed "as is" without any
  16  * warranty of any kind, whether express or implied.
  17  */
  18
  19 #include <linux/module.h>
  20 #include <linux/moduleparam.h>
  21 #include <linux/types.h>
  22 #include <linux/kernel.h>
  23 #include <linux/fs.h>
  24 #include <linux/miscdevice.h>
  25 #include <linux/watchdog.h>
  26 #include <linux/init.h>
  27 #include <linux/bitops.h>
  28 #include <linux/ioport.h>
  29 #include <linux/uaccess.h>
  30
  31 #include <asm/coldfire.h>
  32 #include <asm/m548xsim.h>
  33 #include <asm/m548xgpt.h>
  34
  35 static int nowayout = WATCHDOG_NOWAYOUT;
  36 static unsigned int heartbeat = 30;     /* (secs) Default is 0.5 minute */
  37 static unsigned long wdt_status;
  38
  39 #define WDT_IN_USE              0
  40 #define WDT_OK_TO_CLOSE         1
  41
  42 static void wdt_enable(void)
  43 {
  44         unsigned int gms0;
  45
  46         /* preserve GPIO usage, if any */
  47         gms0 = __raw_readl(MCF_MBAR + MCF_GPT_GMS0);
  48         if (gms0 & MCF_GPT_GMS_TMS_GPIO)
  49                 gms0 &= (MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_GPIO_MASK
  50                                                         | MCF_GPT_GMS_OD);
  51         else
  52                 gms0 = MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_OD;
  53         __raw_writel(gms0, MCF_MBAR + MCF_GPT_GMS0);
  54         __raw_writel(MCF_GPT_GCIR_PRE(heartbeat*(MCF_BUSCLK/0xffff)) |
  55                         MCF_GPT_GCIR_CNT(0xffff), MCF_MBAR + MCF_GPT_GCIR0);
  56         gms0 |= MCF_GPT_GMS_OCPW(0xA5) | MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE;
  57         __raw_writel(gms0, MCF_MBAR + MCF_GPT_GMS0);
  58 }
  59
  60 static void wdt_disable(void)
  61 {
  62         unsigned int gms0;
  63
  64         /* disable watchdog */
  65         gms0 = __raw_readl(MCF_MBAR + MCF_GPT_GMS0);
  66         gms0 &= ~(MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE);
  67         __raw_writel(gms0, MCF_MBAR + MCF_GPT_GMS0);
  68 }
  69
  70 static void wdt_keepalive(void)
  71 {
  72         unsigned int gms0;
  73
  74         gms0 = __raw_readl(MCF_MBAR + MCF_GPT_GMS0);
  75         gms0 |= MCF_GPT_GMS_OCPW(0xA5);
  76         __raw_writel(gms0, MCF_MBAR + MCF_GPT_GMS0);
  77 }
  78
  79 static int m548x_wdt_open(struct inode *inode, struct file *file)
  80 {
  81         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  82                 return -EBUSY;
  83
  84         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  85         wdt_enable();
  86         return nonseekable_open(inode, file);
  87 }
  88
  89 static ssize_t m548x_wdt_write(struct file *file, const char *data,
  90                                                 size_t len, loff_t *ppos)
  91 {
  92         if (len) {
  93                 if (!nowayout) {
  94                         size_t i;
  95
  96                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  97
  98                         for (i = 0; i != len; i++) {
  99                                 char c;
 100
 101                                 if (get_user(c, data + i))
 102                                         return -EFAULT;
 103                                 if (c == 'V')
 104                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 105                         }
 106                 }
 107                 wdt_keepalive();
 108         }
 109         return len;
 110 }
 111
 112 static const struct watchdog_info ident = {
 113         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
 114                                 WDIOF_KEEPALIVEPING,
 115         .identity       = "Coldfire M548x Watchdog",
 116 };
 117
 118 static long m548x_wdt_ioctl(struct file *file, unsigned int cmd,
 119                                                          unsigned long arg)
 120 {
 121         int ret = -ENOTTY;
 122         int time;
 123
 124         switch (cmd) {
 125         case WDIOC_GETSUPPORT:
 126                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 127                                    sizeof(ident)) ? -EFAULT : 0;
 128                 break;
 129
 130         case WDIOC_GETSTATUS:
 131                 ret = put_user(0, (int *)arg);
 132                 break;
 133
 134         case WDIOC_GETBOOTSTATUS:
 135                 ret = put_user(0, (int *)arg);
 136                 break;
 137
 138         case WDIOC_KEEPALIVE:
 139                 wdt_keepalive();
 140                 ret = 0;
 141                 break;
 142
 143         case WDIOC_SETTIMEOUT:
 144                 ret = get_user(time, (int *)arg);
 145                 if (ret)
 146                         break;
 147
 148                 if (time <= 0 || time > 30) {
 149                         ret = -EINVAL;
 150                         break;
 151                 }
 152
 153                 heartbeat = time;
 154                 wdt_enable();
 155                 /* Fall through */
 156
 157         case WDIOC_GETTIMEOUT:
 158                 ret = put_user(heartbeat, (int *)arg);
 159                 break;
 160         }
 161         return ret;
 162 }
 163
 164 static int m548x_wdt_release(struct inode *inode, struct file *file)
 165 {
 166         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 167                 wdt_disable();
 168         else {
 169                 printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "
 170                                         "timer will not stop\n");
 171                 wdt_keepalive();
 172         }
 173         clear_bit(WDT_IN_USE, &wdt_status);
 174         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 175
 176         return 0;
 177 }
 178
 179
 180 static const struct file_operations m548x_wdt_fops = {
 181         .owner          = THIS_MODULE,
 182         .llseek         = no_llseek,
 183         .write          = m548x_wdt_write,
 184         .unlocked_ioctl = m548x_wdt_ioctl,
 185         .open           = m548x_wdt_open,
 186         .release        = m548x_wdt_release,
 187 };
 188
 189 static struct miscdevice m548x_wdt_miscdev = {
 190         .minor          = WATCHDOG_MINOR,
 191         .name           = "watchdog",
 192         .fops           = &m548x_wdt_fops,
 193 };
 194
 195 static int __init m548x_wdt_init(void)
 196 {
 197         if (!request_mem_region(MCF_MBAR + MCF_GPT_GCIR0, 4,
 198                                                 "Coldfire M548x Watchdog")) {
 199                 printk(KERN_WARNING
 200                                 "Coldfire M548x Watchdog : I/O region busy\n");
 201                 return -EBUSY;
 202         }
 203         printk(KERN_INFO "ColdFire watchdog driver is loaded.\n");
 204
 205         return misc_register(&m548x_wdt_miscdev);
 206 }
 207
 208 static void __exit m548x_wdt_exit(void)
 209 {
 210         misc_deregister(&m548x_wdt_miscdev);
 211         release_mem_region(MCF_MBAR + MCF_GPT_GCIR0, 4);
 212 }
 213
 214 module_init(m548x_wdt_init);
 215 module_exit(m548x_wdt_exit);
 216
 217 MODULE_AUTHOR("Philippe De Muyter <phdm@macqel.be>");
 218 MODULE_DESCRIPTION("Coldfire M548x Watchdog");
 219
 220 module_param(heartbeat, int, 0);
 221 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 30s)");
 222
 223 module_param(nowayout, int, 0);
 224 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 225
 226 MODULE_LICENSE("GPL");
 227 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);