drivers/watchdog/lantiq_wdt.c

   1 /*
   2  *  This program is free software; you can redistribute it and/or modify it
   3  *  under the terms of the GNU General Public License version 2 as published
   4  *  by the Free Software Foundation.
   5  *
   6  *  Copyright (C) 2010 John Crispin <blogic@openwrt.org>
   7  *  Based on EP93xx wdt driver
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/fs.h>
  12 #include <linux/miscdevice.h>
  13 #include <linux/watchdog.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/uaccess.h>
  16 #include <linux/clk.h>
  17 #include <linux/io.h>
  18
  19 #include <lantiq.h>
  20
  21 /* Section 3.4 of the datasheet
  22  * The password sequence protects the WDT control register from unintended
  23  * write actions, which might cause malfunction of the WDT.
  24  *
  25  * essentially the following two magic passwords need to be written to allow
  26  * IO access to the WDT core
  27  */
  28 #define LTQ_WDT_PW1             0x00BE0000
  29 #define LTQ_WDT_PW2             0x00DC0000
  30
  31 #define LTQ_WDT_CR              0x0     /* watchdog control register */
  32 #define LTQ_WDT_SR              0x8     /* watchdog status register */
  33
  34 #define LTQ_WDT_SR_EN           (0x1 << 31)     /* enable bit */
  35 #define LTQ_WDT_SR_PWD          (0x3 << 26)     /* turn on power */
  36 #define LTQ_WDT_SR_CLKDIV       (0x3 << 24)     /* turn on clock and set */
  37                                                 /* divider to 0x40000 */
  38 #define LTQ_WDT_DIVIDER         0x40000
  39 #define LTQ_MAX_TIMEOUT         ((1 << 16) - 1) /* the reload field is 16 bit */
  40
  41 static int nowayout = WATCHDOG_NOWAYOUT;
  42
  43 static void __iomem *ltq_wdt_membase;
  44 static unsigned long ltq_io_region_clk_rate;
  45
  46 static unsigned long ltq_wdt_bootstatus;
  47 static unsigned long ltq_wdt_in_use;
  48 static int ltq_wdt_timeout = 30;
  49 static int ltq_wdt_ok_to_close;
  50
  51 static void
  52 ltq_wdt_enable(void)
  53 {
  54         unsigned long int timeout = ltq_wdt_timeout *
  55                         (ltq_io_region_clk_rate / LTQ_WDT_DIVIDER) + 0x1000;
  56         if (timeout > LTQ_MAX_TIMEOUT)
  57                 timeout = LTQ_MAX_TIMEOUT;
  58
  59         /* write the first password magic */
  60         ltq_w32(LTQ_WDT_PW1, ltq_wdt_membase + LTQ_WDT_CR);
  61         /* write the second magic plus the configuration and new timeout */
  62         ltq_w32(LTQ_WDT_SR_EN | LTQ_WDT_SR_PWD | LTQ_WDT_SR_CLKDIV |
  63                 LTQ_WDT_PW2 | timeout, ltq_wdt_membase + LTQ_WDT_CR);
  64 }
  65
  66 static void
  67 ltq_wdt_disable(void)
  68 {
  69         /* write the first password magic */
  70         ltq_w32(LTQ_WDT_PW1, ltq_wdt_membase + LTQ_WDT_CR);
  71         /* write the second password magic with no config
  72          * this turns the watchdog off
  73          */
  74         ltq_w32(LTQ_WDT_PW2, ltq_wdt_membase + LTQ_WDT_CR);
  75 }
  76
  77 static ssize_t
  78 ltq_wdt_write(struct file *file, const char __user *data,
  79                 size_t len, loff_t *ppos)
  80 {
  81         if (len) {
  82                 if (!nowayout) {
  83                         size_t i;
  84
  85                         ltq_wdt_ok_to_close = 0;
  86                         for (i = 0; i != len; i++) {
  87                                 char c;
  88
  89                                 if (get_user(c, data + i))
  90                                         return -EFAULT;
  91                                 if (c == 'V')
  92                                         ltq_wdt_ok_to_close = 1;
  93                                 else
  94                                         ltq_wdt_ok_to_close = 0;
  95                         }
  96                 }
  97                 ltq_wdt_enable();
  98         }
  99
 100         return len;
 101 }
 102
 103 static struct watchdog_info ident = {
 104         .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 105                         WDIOF_CARDRESET,
 106         .identity = "ltq_wdt",
 107 };
 108
 109 static long
 110 ltq_wdt_ioctl(struct file *file,
 111                 unsigned int cmd, unsigned long arg)
 112 {
 113         int ret = -ENOTTY;
 114
 115         switch (cmd) {
 116         case WDIOC_GETSUPPORT:
 117                 ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
 118                                 sizeof(ident)) ? -EFAULT : 0;
 119                 break;
 120
 121         case WDIOC_GETBOOTSTATUS:
 122                 ret = put_user(ltq_wdt_bootstatus, (int __user *)arg);
 123                 break;
 124
 125         case WDIOC_GETSTATUS:
 126                 ret = put_user(0, (int __user *)arg);
 127                 break;
 128
 129         case WDIOC_SETTIMEOUT:
 130                 ret = get_user(ltq_wdt_timeout, (int __user *)arg);
 131                 if (!ret)
 132                         ltq_wdt_enable();
 133                 /* intentional drop through */
 134         case WDIOC_GETTIMEOUT:
 135                 ret = put_user(ltq_wdt_timeout, (int __user *)arg);
 136                 break;
 137
 138         case WDIOC_KEEPALIVE:
 139                 ltq_wdt_enable();
 140                 ret = 0;
 141                 break;
 142         }
 143         return ret;
 144 }
 145
 146 static int
 147 ltq_wdt_open(struct inode *inode, struct file *file)
 148 {
 149         if (test_and_set_bit(0, &ltq_wdt_in_use))
 150                 return -EBUSY;
 151         ltq_wdt_in_use = 1;
 152         ltq_wdt_enable();
 153
 154         return nonseekable_open(inode, file);
 155 }
 156
 157 static int
 158 ltq_wdt_release(struct inode *inode, struct file *file)
 159 {
 160         if (ltq_wdt_ok_to_close)
 161                 ltq_wdt_disable();
 162         else
 163                 pr_err("ltq_wdt: watchdog closed without warning\n");
 164         ltq_wdt_ok_to_close = 0;
 165         clear_bit(0, &ltq_wdt_in_use);
 166
 167         return 0;
 168 }
 169
 170 static const struct file_operations ltq_wdt_fops = {
 171         .owner          = THIS_MODULE,
 172         .write          = ltq_wdt_write,
 173         .unlocked_ioctl = ltq_wdt_ioctl,
 174         .open           = ltq_wdt_open,
 175         .release        = ltq_wdt_release,
 176         .llseek         = no_llseek,
 177 };
 178
 179 static struct miscdevice ltq_wdt_miscdev = {
 180         .minor  = WATCHDOG_MINOR,
 181         .name   = "watchdog",
 182         .fops   = &ltq_wdt_fops,
 183 };
 184
 185 static int __init
 186 ltq_wdt_probe(struct platform_device *pdev)
 187 {
 188         struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 189         struct clk *clk;
 190
 191         if (!res) {
 192                 dev_err(&pdev->dev, "cannot obtain I/O memory region");
 193                 return -ENOENT;
 194         }
 195         res = devm_request_mem_region(&pdev->dev, res->start,
 196                 resource_size(res), dev_name(&pdev->dev));
 197         if (!res) {
 198                 dev_err(&pdev->dev, "cannot request I/O memory region");
 199                 return -EBUSY;
 200         }
 201         ltq_wdt_membase = devm_ioremap_nocache(&pdev->dev, res->start,
 202                 resource_size(res));
 203         if (!ltq_wdt_membase) {
 204                 dev_err(&pdev->dev, "cannot remap I/O memory region\n");
 205                 return -ENOMEM;
 206         }
 207
 208         /* we do not need to enable the clock as it is always running */
 209         clk = clk_get(&pdev->dev, "io");
 210         WARN_ON(!clk);
 211         ltq_io_region_clk_rate = clk_get_rate(clk);
 212         clk_put(clk);
 213
 214         if (ltq_reset_cause() == LTQ_RST_CAUSE_WDTRST)
 215                 ltq_wdt_bootstatus = WDIOF_CARDRESET;
 216
 217         return misc_register(&ltq_wdt_miscdev);
 218 }
 219
 220 static int __devexit
 221 ltq_wdt_remove(struct platform_device *pdev)
 222 {
 223         misc_deregister(&ltq_wdt_miscdev);
 224
 225         if (ltq_wdt_membase)
 226                 iounmap(ltq_wdt_membase);
 227
 228         return 0;
 229 }
 230
 231
 232 static struct platform_driver ltq_wdt_driver = {
 233         .remove = __devexit_p(ltq_wdt_remove),
 234         .driver = {
 235                 .name = "ltq_wdt",
 236                 .owner = THIS_MODULE,
 237         },
 238 };
 239
 240 static int __init
 241 init_ltq_wdt(void)
 242 {
 243         return platform_driver_probe(&ltq_wdt_driver, ltq_wdt_probe);
 244 }
 245
 246 static void __exit
 247 exit_ltq_wdt(void)
 248 {
 249         return platform_driver_unregister(&ltq_wdt_driver);
 250 }
 251
 252 module_init(init_ltq_wdt);
 253 module_exit(exit_ltq_wdt);
 254
 255 module_param(nowayout, int, 0);
 256 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 257
 258 MODULE_AUTHOR("John Crispin <blogic@openwrt.org>");
 259 MODULE_DESCRIPTION("Lantiq SoC Watchdog");
 260 MODULE_LICENSE("GPL");
 261 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);