Jamie Iles | c9353ae | 2011-01-24 12:19:12 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Copyright 2010-2011 Picochip Ltd., Jamie Iles |
| 3 | * http://www.picochip.com |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or |
| 6 | * modify it under the terms of the GNU General Public License |
| 7 | * as published by the Free Software Foundation; either version |
| 8 | * 2 of the License, or (at your option) any later version. |
| 9 | * |
| 10 | * This file implements a driver for the Synopsys DesignWare watchdog device |
| 11 | * in the many ARM subsystems. The watchdog has 16 different timeout periods |
| 12 | * and these are a function of the input clock frequency. |
| 13 | * |
| 14 | * The DesignWare watchdog cannot be stopped once it has been started so we |
| 15 | * use a software timer to implement a ping that will keep the watchdog alive. |
| 16 | * If we receive an expected close for the watchdog then we keep the timer |
| 17 | * running, otherwise the timer is stopped and the watchdog will expire. |
| 18 | */ |
Joe Perches | 27c766a | 2012-02-15 15:06:19 -0800 | [diff] [blame] | 19 | |
| 20 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
Jamie Iles | c9353ae | 2011-01-24 12:19:12 +0000 | [diff] [blame] | 21 | |
| 22 | #include <linux/bitops.h> |
| 23 | #include <linux/clk.h> |
| 24 | #include <linux/device.h> |
| 25 | #include <linux/err.h> |
| 26 | #include <linux/fs.h> |
| 27 | #include <linux/io.h> |
| 28 | #include <linux/kernel.h> |
| 29 | #include <linux/miscdevice.h> |
| 30 | #include <linux/module.h> |
| 31 | #include <linux/moduleparam.h> |
| 32 | #include <linux/pm.h> |
| 33 | #include <linux/platform_device.h> |
| 34 | #include <linux/spinlock.h> |
| 35 | #include <linux/timer.h> |
| 36 | #include <linux/uaccess.h> |
| 37 | #include <linux/watchdog.h> |
| 38 | |
| 39 | #define WDOG_CONTROL_REG_OFFSET 0x00 |
| 40 | #define WDOG_CONTROL_REG_WDT_EN_MASK 0x01 |
| 41 | #define WDOG_TIMEOUT_RANGE_REG_OFFSET 0x04 |
| 42 | #define WDOG_CURRENT_COUNT_REG_OFFSET 0x08 |
| 43 | #define WDOG_COUNTER_RESTART_REG_OFFSET 0x0c |
| 44 | #define WDOG_COUNTER_RESTART_KICK_VALUE 0x76 |
| 45 | |
| 46 | /* The maximum TOP (timeout period) value that can be set in the watchdog. */ |
| 47 | #define DW_WDT_MAX_TOP 15 |
| 48 | |
Wim Van Sebroeck | 86a1e18 | 2012-03-05 16:51:11 +0100 | [diff] [blame] | 49 | static bool nowayout = WATCHDOG_NOWAYOUT; |
| 50 | module_param(nowayout, bool, 0); |
Jamie Iles | c9353ae | 2011-01-24 12:19:12 +0000 | [diff] [blame] | 51 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " |
| 52 | "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
| 53 | |
| 54 | #define WDT_TIMEOUT (HZ / 2) |
| 55 | |
| 56 | static struct { |
| 57 | spinlock_t lock; |
| 58 | void __iomem *regs; |
| 59 | struct clk *clk; |
| 60 | unsigned long in_use; |
| 61 | unsigned long next_heartbeat; |
| 62 | struct timer_list timer; |
| 63 | int expect_close; |
| 64 | } dw_wdt; |
| 65 | |
| 66 | static inline int dw_wdt_is_enabled(void) |
| 67 | { |
| 68 | return readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET) & |
| 69 | WDOG_CONTROL_REG_WDT_EN_MASK; |
| 70 | } |
| 71 | |
| 72 | static inline int dw_wdt_top_in_seconds(unsigned top) |
| 73 | { |
| 74 | /* |
| 75 | * There are 16 possible timeout values in 0..15 where the number of |
| 76 | * cycles is 2 ^ (16 + i) and the watchdog counts down. |
| 77 | */ |
| 78 | return (1 << (16 + top)) / clk_get_rate(dw_wdt.clk); |
| 79 | } |
| 80 | |
| 81 | static int dw_wdt_get_top(void) |
| 82 | { |
| 83 | int top = readl(dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF; |
| 84 | |
| 85 | return dw_wdt_top_in_seconds(top); |
| 86 | } |
| 87 | |
| 88 | static inline void dw_wdt_set_next_heartbeat(void) |
| 89 | { |
| 90 | dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ; |
| 91 | } |
| 92 | |
| 93 | static int dw_wdt_set_top(unsigned top_s) |
| 94 | { |
| 95 | int i, top_val = DW_WDT_MAX_TOP; |
| 96 | |
| 97 | /* |
| 98 | * Iterate over the timeout values until we find the closest match. We |
| 99 | * always look for >=. |
| 100 | */ |
| 101 | for (i = 0; i <= DW_WDT_MAX_TOP; ++i) |
| 102 | if (dw_wdt_top_in_seconds(i) >= top_s) { |
| 103 | top_val = i; |
| 104 | break; |
| 105 | } |
| 106 | |
| 107 | /* Set the new value in the watchdog. */ |
| 108 | writel(top_val, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET); |
| 109 | |
| 110 | dw_wdt_set_next_heartbeat(); |
| 111 | |
| 112 | return dw_wdt_top_in_seconds(top_val); |
| 113 | } |
| 114 | |
| 115 | static void dw_wdt_keepalive(void) |
| 116 | { |
| 117 | writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs + |
| 118 | WDOG_COUNTER_RESTART_REG_OFFSET); |
| 119 | } |
| 120 | |
| 121 | static void dw_wdt_ping(unsigned long data) |
| 122 | { |
| 123 | if (time_before(jiffies, dw_wdt.next_heartbeat) || |
| 124 | (!nowayout && !dw_wdt.in_use)) { |
| 125 | dw_wdt_keepalive(); |
| 126 | mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT); |
| 127 | } else |
| 128 | pr_crit("keepalive missed, machine will reset\n"); |
| 129 | } |
| 130 | |
| 131 | static int dw_wdt_open(struct inode *inode, struct file *filp) |
| 132 | { |
| 133 | if (test_and_set_bit(0, &dw_wdt.in_use)) |
| 134 | return -EBUSY; |
| 135 | |
| 136 | /* Make sure we don't get unloaded. */ |
| 137 | __module_get(THIS_MODULE); |
| 138 | |
| 139 | spin_lock(&dw_wdt.lock); |
| 140 | if (!dw_wdt_is_enabled()) { |
| 141 | /* |
| 142 | * The watchdog is not currently enabled. Set the timeout to |
| 143 | * the maximum and then start it. |
| 144 | */ |
| 145 | dw_wdt_set_top(DW_WDT_MAX_TOP); |
| 146 | writel(WDOG_CONTROL_REG_WDT_EN_MASK, |
| 147 | dw_wdt.regs + WDOG_CONTROL_REG_OFFSET); |
| 148 | } |
| 149 | |
| 150 | dw_wdt_set_next_heartbeat(); |
| 151 | |
| 152 | spin_unlock(&dw_wdt.lock); |
| 153 | |
| 154 | return nonseekable_open(inode, filp); |
| 155 | } |
| 156 | |
| 157 | ssize_t dw_wdt_write(struct file *filp, const char __user *buf, size_t len, |
| 158 | loff_t *offset) |
| 159 | { |
| 160 | if (!len) |
| 161 | return 0; |
| 162 | |
| 163 | if (!nowayout) { |
| 164 | size_t i; |
| 165 | |
| 166 | dw_wdt.expect_close = 0; |
| 167 | |
| 168 | for (i = 0; i < len; ++i) { |
| 169 | char c; |
| 170 | |
| 171 | if (get_user(c, buf + i)) |
| 172 | return -EFAULT; |
| 173 | |
| 174 | if (c == 'V') { |
| 175 | dw_wdt.expect_close = 1; |
| 176 | break; |
| 177 | } |
| 178 | } |
| 179 | } |
| 180 | |
| 181 | dw_wdt_set_next_heartbeat(); |
| 182 | mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT); |
| 183 | |
| 184 | return len; |
| 185 | } |
| 186 | |
| 187 | static u32 dw_wdt_time_left(void) |
| 188 | { |
| 189 | return readl(dw_wdt.regs + WDOG_CURRENT_COUNT_REG_OFFSET) / |
| 190 | clk_get_rate(dw_wdt.clk); |
| 191 | } |
| 192 | |
| 193 | static const struct watchdog_info dw_wdt_ident = { |
| 194 | .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | |
| 195 | WDIOF_MAGICCLOSE, |
| 196 | .identity = "Synopsys DesignWare Watchdog", |
| 197 | }; |
| 198 | |
| 199 | static long dw_wdt_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) |
| 200 | { |
| 201 | unsigned long val; |
| 202 | int timeout; |
| 203 | |
| 204 | switch (cmd) { |
| 205 | case WDIOC_GETSUPPORT: |
| 206 | return copy_to_user((struct watchdog_info *)arg, &dw_wdt_ident, |
| 207 | sizeof(dw_wdt_ident)) ? -EFAULT : 0; |
| 208 | |
| 209 | case WDIOC_GETSTATUS: |
| 210 | case WDIOC_GETBOOTSTATUS: |
| 211 | return put_user(0, (int *)arg); |
| 212 | |
| 213 | case WDIOC_KEEPALIVE: |
| 214 | dw_wdt_set_next_heartbeat(); |
| 215 | return 0; |
| 216 | |
| 217 | case WDIOC_SETTIMEOUT: |
| 218 | if (get_user(val, (int __user *)arg)) |
| 219 | return -EFAULT; |
| 220 | timeout = dw_wdt_set_top(val); |
| 221 | return put_user(timeout , (int __user *)arg); |
| 222 | |
| 223 | case WDIOC_GETTIMEOUT: |
| 224 | return put_user(dw_wdt_get_top(), (int __user *)arg); |
| 225 | |
| 226 | case WDIOC_GETTIMELEFT: |
| 227 | /* Get the time left until expiry. */ |
| 228 | if (get_user(val, (int __user *)arg)) |
| 229 | return -EFAULT; |
| 230 | return put_user(dw_wdt_time_left(), (int __user *)arg); |
| 231 | |
| 232 | default: |
| 233 | return -ENOTTY; |
| 234 | } |
| 235 | } |
| 236 | |
| 237 | static int dw_wdt_release(struct inode *inode, struct file *filp) |
| 238 | { |
| 239 | clear_bit(0, &dw_wdt.in_use); |
| 240 | |
| 241 | if (!dw_wdt.expect_close) { |
| 242 | del_timer(&dw_wdt.timer); |
| 243 | |
| 244 | if (!nowayout) |
| 245 | pr_crit("unexpected close, system will reboot soon\n"); |
| 246 | else |
| 247 | pr_crit("watchdog cannot be disabled, system will reboot soon\n"); |
| 248 | } |
| 249 | |
| 250 | dw_wdt.expect_close = 0; |
| 251 | |
| 252 | return 0; |
| 253 | } |
| 254 | |
| 255 | #ifdef CONFIG_PM |
| 256 | static int dw_wdt_suspend(struct device *dev) |
| 257 | { |
| 258 | clk_disable(dw_wdt.clk); |
| 259 | |
| 260 | return 0; |
| 261 | } |
| 262 | |
| 263 | static int dw_wdt_resume(struct device *dev) |
| 264 | { |
| 265 | int err = clk_enable(dw_wdt.clk); |
| 266 | |
| 267 | if (err) |
| 268 | return err; |
| 269 | |
| 270 | dw_wdt_keepalive(); |
| 271 | |
| 272 | return 0; |
| 273 | } |
| 274 | |
| 275 | static const struct dev_pm_ops dw_wdt_pm_ops = { |
| 276 | .suspend = dw_wdt_suspend, |
| 277 | .resume = dw_wdt_resume, |
| 278 | }; |
| 279 | #endif /* CONFIG_PM */ |
| 280 | |
| 281 | static const struct file_operations wdt_fops = { |
| 282 | .owner = THIS_MODULE, |
| 283 | .llseek = no_llseek, |
| 284 | .open = dw_wdt_open, |
| 285 | .write = dw_wdt_write, |
| 286 | .unlocked_ioctl = dw_wdt_ioctl, |
| 287 | .release = dw_wdt_release |
| 288 | }; |
| 289 | |
| 290 | static struct miscdevice dw_wdt_miscdev = { |
| 291 | .fops = &wdt_fops, |
| 292 | .name = "watchdog", |
| 293 | .minor = WATCHDOG_MINOR, |
| 294 | }; |
| 295 | |
Bill Pemberton | 2d991a1 | 2012-11-19 13:21:41 -0500 | [diff] [blame] | 296 | static int dw_wdt_drv_probe(struct platform_device *pdev) |
Jamie Iles | c9353ae | 2011-01-24 12:19:12 +0000 | [diff] [blame] | 297 | { |
| 298 | int ret; |
| 299 | struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
| 300 | |
| 301 | if (!mem) |
| 302 | return -EINVAL; |
| 303 | |
Thierry Reding | 4c271bb | 2013-01-21 11:09:25 +0100 | [diff] [blame] | 304 | dw_wdt.regs = devm_ioremap_resource(&pdev->dev, mem); |
| 305 | if (IS_ERR(dw_wdt.regs)) |
| 306 | return PTR_ERR(dw_wdt.regs); |
Jamie Iles | c9353ae | 2011-01-24 12:19:12 +0000 | [diff] [blame] | 307 | |
| 308 | dw_wdt.clk = clk_get(&pdev->dev, NULL); |
| 309 | if (IS_ERR(dw_wdt.clk)) |
| 310 | return PTR_ERR(dw_wdt.clk); |
| 311 | |
| 312 | ret = clk_enable(dw_wdt.clk); |
| 313 | if (ret) |
| 314 | goto out_put_clk; |
| 315 | |
| 316 | spin_lock_init(&dw_wdt.lock); |
| 317 | |
| 318 | ret = misc_register(&dw_wdt_miscdev); |
| 319 | if (ret) |
| 320 | goto out_disable_clk; |
| 321 | |
| 322 | dw_wdt_set_next_heartbeat(); |
| 323 | setup_timer(&dw_wdt.timer, dw_wdt_ping, 0); |
| 324 | mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT); |
| 325 | |
| 326 | return 0; |
| 327 | |
| 328 | out_disable_clk: |
| 329 | clk_disable(dw_wdt.clk); |
| 330 | out_put_clk: |
| 331 | clk_put(dw_wdt.clk); |
| 332 | |
| 333 | return ret; |
| 334 | } |
| 335 | |
Bill Pemberton | 4b12b89 | 2012-11-19 13:26:24 -0500 | [diff] [blame] | 336 | static int dw_wdt_drv_remove(struct platform_device *pdev) |
Jamie Iles | c9353ae | 2011-01-24 12:19:12 +0000 | [diff] [blame] | 337 | { |
| 338 | misc_deregister(&dw_wdt_miscdev); |
| 339 | |
| 340 | clk_disable(dw_wdt.clk); |
| 341 | clk_put(dw_wdt.clk); |
| 342 | |
| 343 | return 0; |
| 344 | } |
| 345 | |
| 346 | static struct platform_driver dw_wdt_driver = { |
| 347 | .probe = dw_wdt_drv_probe, |
Bill Pemberton | 8226871 | 2012-11-19 13:21:12 -0500 | [diff] [blame] | 348 | .remove = dw_wdt_drv_remove, |
Jamie Iles | c9353ae | 2011-01-24 12:19:12 +0000 | [diff] [blame] | 349 | .driver = { |
| 350 | .name = "dw_wdt", |
| 351 | .owner = THIS_MODULE, |
| 352 | #ifdef CONFIG_PM |
| 353 | .pm = &dw_wdt_pm_ops, |
| 354 | #endif /* CONFIG_PM */ |
| 355 | }, |
| 356 | }; |
| 357 | |
Axel Lin | b8ec611 | 2011-11-29 13:56:27 +0800 | [diff] [blame] | 358 | module_platform_driver(dw_wdt_driver); |
Jamie Iles | c9353ae | 2011-01-24 12:19:12 +0000 | [diff] [blame] | 359 | |
| 360 | MODULE_AUTHOR("Jamie Iles"); |
| 361 | MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver"); |
| 362 | MODULE_LICENSE("GPL"); |
| 363 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |