drivers/watchdog/m54xx_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * drivers/watchdog/m54xx_wdt.c
   4  *
   5  * Watchdog driver for ColdFire MCF547x & MCF548x processors
   6  * Copyright 2010 (c) Philippe De Muyter <phdm@macqel.be>
   7  *
   8  * Adapted from the IXP4xx watchdog driver, which carries these notices:
   9  *
  10  *  Author: Deepak Saxena <dsaxena@plexity.net>
  11  *
  12  *  Copyright 2004 (c) MontaVista, Software, Inc.
  13  *  Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
  14  *
  15  */
  16
  17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  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 #include <linux/io.h>
  31
  32 #include <asm/coldfire.h>
  33 #include <asm/m54xxsim.h>
  34 #include <asm/m54xxgpt.h>
  35
  36 static bool nowayout = WATCHDOG_NOWAYOUT;
  37 static unsigned int heartbeat = 30;     /* (secs) Default is 0.5 minute */
  38 static unsigned long wdt_status;
  39
  40 #define WDT_IN_USE              0
  41 #define WDT_OK_TO_CLOSE         1
  42
  43 static void wdt_enable(void)
  44 {
  45         unsigned int gms0;
  46
  47         /* preserve GPIO usage, if any */
  48         gms0 = __raw_readl(MCF_GPT_GMS0);
  49         if (gms0 & MCF_GPT_GMS_TMS_GPIO)
  50                 gms0 &= (MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_GPIO_MASK
  51                                                         | MCF_GPT_GMS_OD);
  52         else
  53                 gms0 = MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_OD;
  54         __raw_writel(gms0, MCF_GPT_GMS0);
  55         __raw_writel(MCF_GPT_GCIR_PRE(heartbeat*(MCF_BUSCLK/0xffff)) |
  56                         MCF_GPT_GCIR_CNT(0xffff), MCF_GPT_GCIR0);
  57         gms0 |= MCF_GPT_GMS_OCPW(0xA5) | MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE;
  58         __raw_writel(gms0, MCF_GPT_GMS0);
  59 }
  60
  61 static void wdt_disable(void)
  62 {
  63         unsigned int gms0;
  64
  65         /* disable watchdog */
  66         gms0 = __raw_readl(MCF_GPT_GMS0);
  67         gms0 &= ~(MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE);
  68         __raw_writel(gms0, MCF_GPT_GMS0);
  69 }
  70
  71 static void wdt_keepalive(void)
  72 {
  73         unsigned int gms0;
  74
  75         gms0 = __raw_readl(MCF_GPT_GMS0);
  76         gms0 |= MCF_GPT_GMS_OCPW(0xA5);
  77         __raw_writel(gms0, MCF_GPT_GMS0);
  78 }
  79
  80 static int m54xx_wdt_open(struct inode *inode, struct file *file)
  81 {
  82         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  83                 return -EBUSY;
  84
  85         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  86         wdt_enable();
  87         return stream_open(inode, file);
  88 }
  89
  90 static ssize_t m54xx_wdt_write(struct file *file, const char *data,
  91                                                 size_t len, loff_t *ppos)
  92 {
  93         if (len) {
  94                 if (!nowayout) {
  95                         size_t i;
  96
  97                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  98
  99                         for (i = 0; i != len; i++) {
 100                                 char c;
 101
 102                                 if (get_user(c, data + i))
 103                                         return -EFAULT;
 104                                 if (c == 'V')
 105                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 106                         }
 107                 }
 108                 wdt_keepalive();
 109         }
 110         return len;
 111 }
 112
 113 static const struct watchdog_info ident = {
 114         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
 115                                 WDIOF_KEEPALIVEPING,
 116         .identity       = "Coldfire M54xx Watchdog",
 117 };
 118
 119 static long m54xx_wdt_ioctl(struct file *file, unsigned int cmd,
 120                                                          unsigned long arg)
 121 {
 122         int ret = -ENOTTY;
 123         int time;
 124
 125         switch (cmd) {
 126         case WDIOC_GETSUPPORT:
 127                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 128                                    sizeof(ident)) ? -EFAULT : 0;
 129                 break;
 130
 131         case WDIOC_GETSTATUS:
 132                 ret = put_user(0, (int *)arg);
 133                 break;
 134
 135         case WDIOC_GETBOOTSTATUS:
 136                 ret = put_user(0, (int *)arg);
 137                 break;
 138
 139         case WDIOC_KEEPALIVE:
 140                 wdt_keepalive();
 141                 ret = 0;
 142                 break;
 143
 144         case WDIOC_SETTIMEOUT:
 145                 ret = get_user(time, (int *)arg);
 146                 if (ret)
 147                         break;
 148
 149                 if (time <= 0 || time > 30) {
 150                         ret = -EINVAL;
 151                         break;
 152                 }
 153
 154                 heartbeat = time;
 155                 wdt_enable();
 156                 fallthrough;
 157
 158         case WDIOC_GETTIMEOUT:
 159                 ret = put_user(heartbeat, (int *)arg);
 160                 break;
 161         }
 162         return ret;
 163 }
 164
 165 static int m54xx_wdt_release(struct inode *inode, struct file *file)
 166 {
 167         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 168                 wdt_disable();
 169         else {
 170                 pr_crit("Device closed unexpectedly - 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 m54xx_wdt_fops = {
 181         .owner          = THIS_MODULE,
 182         .write          = m54xx_wdt_write,
 183         .unlocked_ioctl = m54xx_wdt_ioctl,
 184         .compat_ioctl   = compat_ptr_ioctl,
 185         .open           = m54xx_wdt_open,
 186         .release        = m54xx_wdt_release,
 187 };
 188
 189 static struct miscdevice m54xx_wdt_miscdev = {
 190         .minor          = WATCHDOG_MINOR,
 191         .name           = "watchdog",
 192         .fops           = &m54xx_wdt_fops,
 193 };
 194
 195 static int __init m54xx_wdt_init(void)
 196 {
 197         if (!request_mem_region(MCF_GPT_GCIR0, 4, "Coldfire M54xx Watchdog")) {
 198                 pr_warn("I/O region busy\n");
 199                 return -EBUSY;
 200         }
 201         pr_info("driver is loaded\n");
 202
 203         return misc_register(&m54xx_wdt_miscdev);
 204 }
 205
 206 static void __exit m54xx_wdt_exit(void)
 207 {
 208         misc_deregister(&m54xx_wdt_miscdev);
 209         release_mem_region(MCF_GPT_GCIR0, 4);
 210 }
 211
 212 module_init(m54xx_wdt_init);
 213 module_exit(m54xx_wdt_exit);
 214
 215 MODULE_AUTHOR("Philippe De Muyter <phdm@macqel.be>");
 216 MODULE_DESCRIPTION("Coldfire M54xx Watchdog");
 217
 218 module_param(heartbeat, int, 0);
 219 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 30s)");
 220
 221 module_param(nowayout, bool, 0);
 222 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 223
 224 MODULE_LICENSE("GPL");