drivers/watchdog/sa1100_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  *      Watchdog driver for the SA11x0/PXA2xx
   4  *
   5  *      (c) Copyright 2000 Oleg Drokin <green@crimea.edu>
   6  *          Based on SoftDog driver by Alan Cox <alan@lxorguk.ukuu.org.uk>
   7  *
   8  *      Neither Oleg Drokin nor iXcelerator.com admit liability nor provide
   9  *      warranty for any of this software. This material is provided
  10  *      "AS-IS" and at no charge.
  11  *
  12  *      (c) Copyright 2000           Oleg Drokin <green@crimea.edu>
  13  *
  14  *      27/11/2000 Initial release
  15  */
  16
  17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  18
  19 #include <linux/module.h>
  20 #include <linux/moduleparam.h>
  21 #include <linux/clk.h>
  22 #include <linux/types.h>
  23 #include <linux/kernel.h>
  24 #include <linux/fs.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/miscdevice.h>
  27 #include <linux/watchdog.h>
  28 #include <linux/init.h>
  29 #include <linux/io.h>
  30 #include <linux/bitops.h>
  31 #include <linux/uaccess.h>
  32 #include <linux/timex.h>
  33
  34 #define REG_OSMR0       0x0000  /* OS timer Match Reg. 0 */
  35 #define REG_OSMR1       0x0004  /* OS timer Match Reg. 1 */
  36 #define REG_OSMR2       0x0008  /* OS timer Match Reg. 2 */
  37 #define REG_OSMR3       0x000c  /* OS timer Match Reg. 3 */
  38 #define REG_OSCR        0x0010  /* OS timer Counter Reg. */
  39 #define REG_OSSR        0x0014  /* OS timer Status Reg. */
  40 #define REG_OWER        0x0018  /* OS timer Watch-dog Enable Reg. */
  41 #define REG_OIER        0x001C  /* OS timer Interrupt Enable Reg. */
  42
  43 #define OSSR_M3         (1 << 3)        /* Match status channel 3 */
  44 #define OSSR_M2         (1 << 2)        /* Match status channel 2 */
  45 #define OSSR_M1         (1 << 1)        /* Match status channel 1 */
  46 #define OSSR_M0         (1 << 0)        /* Match status channel 0 */
  47
  48 #define OWER_WME        (1 << 0)        /* Watchdog Match Enable */
  49
  50 #define OIER_E3         (1 << 3)        /* Interrupt enable channel 3 */
  51 #define OIER_E2         (1 << 2)        /* Interrupt enable channel 2 */
  52 #define OIER_E1         (1 << 1)        /* Interrupt enable channel 1 */
  53 #define OIER_E0         (1 << 0)        /* Interrupt enable channel 0 */
  54
  55 static unsigned long oscr_freq;
  56 static unsigned long sa1100wdt_users;
  57 static unsigned int pre_margin;
  58 static int boot_status;
  59 static void __iomem *reg_base;
  60
  61 static inline void sa1100_wr(u32 val, u32 offset)
  62 {
  63         writel_relaxed(val, reg_base + offset);
  64 }
  65
  66 static inline u32 sa1100_rd(u32 offset)
  67 {
  68         return readl_relaxed(reg_base + offset);
  69 }
  70
  71 /*
  72  *      Allow only one person to hold it open
  73  */
  74 static int sa1100dog_open(struct inode *inode, struct file *file)
  75 {
  76         if (test_and_set_bit(1, &sa1100wdt_users))
  77                 return -EBUSY;
  78
  79         /* Activate SA1100 Watchdog timer */
  80         sa1100_wr(sa1100_rd(REG_OSCR) + pre_margin, REG_OSMR3);
  81         sa1100_wr(OSSR_M3, REG_OSSR);
  82         sa1100_wr(OWER_WME, REG_OWER);
  83         sa1100_wr(sa1100_rd(REG_OIER) | OIER_E3, REG_OIER);
  84         return stream_open(inode, file);
  85 }
  86
  87 /*
  88  * The watchdog cannot be disabled.
  89  *
  90  * Previous comments suggested that turning off the interrupt by
  91  * clearing REG_OIER[E3] would prevent the watchdog timing out but this
  92  * does not appear to be true (at least on the PXA255).
  93  */
  94 static int sa1100dog_release(struct inode *inode, struct file *file)
  95 {
  96         pr_crit("Device closed - timer will not stop\n");
  97         clear_bit(1, &sa1100wdt_users);
  98         return 0;
  99 }
 100
 101 static ssize_t sa1100dog_write(struct file *file, const char __user *data,
 102                                                 size_t len, loff_t *ppos)
 103 {
 104         if (len)
 105                 /* Refresh OSMR3 timer. */
 106                 sa1100_wr(sa1100_rd(REG_OSCR) + pre_margin, REG_OSMR3);
 107         return len;
 108 }
 109
 110 static const struct watchdog_info ident = {
 111         .options        = WDIOF_CARDRESET | WDIOF_SETTIMEOUT
 112                                 | WDIOF_KEEPALIVEPING,
 113         .identity       = "SA1100/PXA255 Watchdog",
 114         .firmware_version       = 1,
 115 };
 116
 117 static long sa1100dog_ioctl(struct file *file, unsigned int cmd,
 118                                                         unsigned long arg)
 119 {
 120         int ret = -ENOTTY;
 121         int time;
 122         void __user *argp = (void __user *)arg;
 123         int __user *p = argp;
 124
 125         switch (cmd) {
 126         case WDIOC_GETSUPPORT:
 127                 ret = copy_to_user(argp, &ident,
 128                                    sizeof(ident)) ? -EFAULT : 0;
 129                 break;
 130
 131         case WDIOC_GETSTATUS:
 132                 ret = put_user(0, p);
 133                 break;
 134
 135         case WDIOC_GETBOOTSTATUS:
 136                 ret = put_user(boot_status, p);
 137                 break;
 138
 139         case WDIOC_KEEPALIVE:
 140                 sa1100_wr(sa1100_rd(REG_OSCR) + pre_margin, REG_OSMR3);
 141                 ret = 0;
 142                 break;
 143
 144         case WDIOC_SETTIMEOUT:
 145                 ret = get_user(time, p);
 146                 if (ret)
 147                         break;
 148
 149                 if (time <= 0 || (oscr_freq * (long long)time >= 0xffffffff)) {
 150                         ret = -EINVAL;
 151                         break;
 152                 }
 153
 154                 pre_margin = oscr_freq * time;
 155                 sa1100_wr(sa1100_rd(REG_OSCR) + pre_margin, REG_OSMR3);
 156                 fallthrough;
 157
 158         case WDIOC_GETTIMEOUT:
 159                 ret = put_user(pre_margin / oscr_freq, p);
 160                 break;
 161         }
 162         return ret;
 163 }
 164
 165 static const struct file_operations sa1100dog_fops = {
 166         .owner          = THIS_MODULE,
 167         .write          = sa1100dog_write,
 168         .unlocked_ioctl = sa1100dog_ioctl,
 169         .compat_ioctl   = compat_ptr_ioctl,
 170         .open           = sa1100dog_open,
 171         .release        = sa1100dog_release,
 172 };
 173
 174 static struct miscdevice sa1100dog_miscdev = {
 175         .minor          = WATCHDOG_MINOR,
 176         .name           = "watchdog",
 177         .fops           = &sa1100dog_fops,
 178 };
 179
 180 static int margin = 60;         /* (secs) Default is 1 minute */
 181 static struct clk *clk;
 182
 183 static int sa1100dog_probe(struct platform_device *pdev)
 184 {
 185         int ret;
 186         int *platform_data;
 187         struct resource *res;
 188
 189         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 190         if (!res)
 191                 return -ENXIO;
 192         reg_base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
 193         if (!reg_base)
 194                 return -ENOMEM;
 195
 196         clk = clk_get(NULL, "OSTIMER0");
 197         if (IS_ERR(clk)) {
 198                 pr_err("SA1100/PXA2xx Watchdog Timer: clock not found: %d\n",
 199                        (int) PTR_ERR(clk));
 200                 return PTR_ERR(clk);
 201         }
 202
 203         ret = clk_prepare_enable(clk);
 204         if (ret) {
 205                 pr_err("SA1100/PXA2xx Watchdog Timer: clock failed to prepare+enable: %d\n",
 206                        ret);
 207                 goto err;
 208         }
 209
 210         oscr_freq = clk_get_rate(clk);
 211
 212         platform_data = pdev->dev.platform_data;
 213         if (platform_data && *platform_data)
 214                 boot_status = WDIOF_CARDRESET;
 215         pre_margin = oscr_freq * margin;
 216
 217         ret = misc_register(&sa1100dog_miscdev);
 218         if (ret == 0) {
 219                 pr_info("SA1100/PXA2xx Watchdog Timer: timer margin %d sec\n",
 220                         margin);
 221                 return 0;
 222         }
 223
 224         clk_disable_unprepare(clk);
 225 err:
 226         clk_put(clk);
 227         return ret;
 228 }
 229
 230 static void sa1100dog_remove(struct platform_device *pdev)
 231 {
 232         misc_deregister(&sa1100dog_miscdev);
 233         clk_disable_unprepare(clk);
 234         clk_put(clk);
 235 }
 236
 237 static struct platform_driver sa1100dog_driver = {
 238         .driver.name = "sa1100_wdt",
 239         .probe    = sa1100dog_probe,
 240         .remove   = sa1100dog_remove,
 241 };
 242 module_platform_driver(sa1100dog_driver);
 243
 244 MODULE_AUTHOR("Oleg Drokin <green@crimea.edu>");
 245 MODULE_DESCRIPTION("SA1100/PXA2xx Watchdog");
 246
 247 module_param(margin, int, 0);
 248 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
 249
 250 MODULE_LICENSE("GPL");