1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Atheros AR71XX/AR724X/AR913X built-in hardware watchdog timer. 4 * 5 * Copyright (C) 2008-2011 Gabor Juhos <juhosg@openwrt.org> 6 * Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org> 7 * 8 * This driver was based on: drivers/watchdog/ixp4xx_wdt.c 9 * Author: Deepak Saxena <dsaxena@plexity.net> 10 * Copyright 2004 (c) MontaVista, Software, Inc. 11 * 12 * which again was based on sa1100 driver, 13 * Copyright (C) 2000 Oleg Drokin <green@crimea.edu> 14 */ 15 16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 17 18 #include <linux/bitops.h> 19 #include <linux/delay.h> 20 #include <linux/errno.h> 21 #include <linux/fs.h> 22 #include <linux/io.h> 23 #include <linux/kernel.h> 24 #include <linux/miscdevice.h> 25 #include <linux/module.h> 26 #include <linux/moduleparam.h> 27 #include <linux/platform_device.h> 28 #include <linux/types.h> 29 #include <linux/watchdog.h> 30 #include <linux/clk.h> 31 #include <linux/err.h> 32 #include <linux/of.h> 33 #include <linux/of_platform.h> 34 #include <linux/uaccess.h> 35 36 #define DRIVER_NAME "ath79-wdt" 37 38 #define WDT_TIMEOUT 15 /* seconds */ 39 40 #define WDOG_REG_CTRL 0x00 41 #define WDOG_REG_TIMER 0x04 42 43 #define WDOG_CTRL_LAST_RESET BIT(31) 44 #define WDOG_CTRL_ACTION_MASK 3 45 #define WDOG_CTRL_ACTION_NONE 0 /* no action */ 46 #define WDOG_CTRL_ACTION_GPI 1 /* general purpose interrupt */ 47 #define WDOG_CTRL_ACTION_NMI 2 /* NMI */ 48 #define WDOG_CTRL_ACTION_FCR 3 /* full chip reset */ 49 50 static bool nowayout = WATCHDOG_NOWAYOUT; 51 module_param(nowayout, bool, 0); 52 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " 53 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 54 55 static int timeout = WDT_TIMEOUT; 56 module_param(timeout, int, 0); 57 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds " 58 "(default=" __MODULE_STRING(WDT_TIMEOUT) "s)"); 59 60 static unsigned long wdt_flags; 61 62 #define WDT_FLAGS_BUSY 0 63 #define WDT_FLAGS_EXPECT_CLOSE 1 64 65 static struct clk *wdt_clk; 66 static unsigned long wdt_freq; 67 static int boot_status; 68 static int max_timeout; 69 static void __iomem *wdt_base; 70 71 static inline void ath79_wdt_wr(unsigned reg, u32 val) 72 { 73 iowrite32(val, wdt_base + reg); 74 } 75 76 static inline u32 ath79_wdt_rr(unsigned reg) 77 { 78 return ioread32(wdt_base + reg); 79 } 80 81 static inline void ath79_wdt_keepalive(void) 82 { 83 ath79_wdt_wr(WDOG_REG_TIMER, wdt_freq * timeout); 84 /* flush write */ 85 ath79_wdt_rr(WDOG_REG_TIMER); 86 } 87 88 static inline void ath79_wdt_enable(void) 89 { 90 ath79_wdt_keepalive(); 91 92 /* 93 * Updating the TIMER register requires a few microseconds 94 * on the AR934x SoCs at least. Use a small delay to ensure 95 * that the TIMER register is updated within the hardware 96 * before enabling the watchdog. 97 */ 98 udelay(2); 99 100 ath79_wdt_wr(WDOG_REG_CTRL, WDOG_CTRL_ACTION_FCR); 101 /* flush write */ 102 ath79_wdt_rr(WDOG_REG_CTRL); 103 } 104 105 static inline void ath79_wdt_disable(void) 106 { 107 ath79_wdt_wr(WDOG_REG_CTRL, WDOG_CTRL_ACTION_NONE); 108 /* flush write */ 109 ath79_wdt_rr(WDOG_REG_CTRL); 110 } 111 112 static int ath79_wdt_set_timeout(int val) 113 { 114 if (val < 1 || val > max_timeout) 115 return -EINVAL; 116 117 timeout = val; 118 ath79_wdt_keepalive(); 119 120 return 0; 121 } 122 123 static int ath79_wdt_open(struct inode *inode, struct file *file) 124 { 125 if (test_and_set_bit(WDT_FLAGS_BUSY, &wdt_flags)) 126 return -EBUSY; 127 128 clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags); 129 ath79_wdt_enable(); 130 131 return stream_open(inode, file); 132 } 133 134 static int ath79_wdt_release(struct inode *inode, struct file *file) 135 { 136 if (test_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags)) 137 ath79_wdt_disable(); 138 else { 139 pr_crit("device closed unexpectedly, watchdog timer will not stop!\n"); 140 ath79_wdt_keepalive(); 141 } 142 143 clear_bit(WDT_FLAGS_BUSY, &wdt_flags); 144 clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags); 145 146 return 0; 147 } 148 149 static ssize_t ath79_wdt_write(struct file *file, const char *data, 150 size_t len, loff_t *ppos) 151 { 152 if (len) { 153 if (!nowayout) { 154 size_t i; 155 156 clear_bit(WDT_FLAGS_EXPECT_CLOSE, &wdt_flags); 157 158 for (i = 0; i != len; i++) { 159 char c; 160 161 if (get_user(c, data + i)) 162 return -EFAULT; 163 164 if (c == 'V') 165 set_bit(WDT_FLAGS_EXPECT_CLOSE, 166 &wdt_flags); 167 } 168 } 169 170 ath79_wdt_keepalive(); 171 } 172 173 return len; 174 } 175 176 static const struct watchdog_info ath79_wdt_info = { 177 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | 178 WDIOF_MAGICCLOSE | WDIOF_CARDRESET, 179 .firmware_version = 0, 180 .identity = "ATH79 watchdog", 181 }; 182 183 static long ath79_wdt_ioctl(struct file *file, unsigned int cmd, 184 unsigned long arg) 185 { 186 void __user *argp = (void __user *)arg; 187 int __user *p = argp; 188 int err; 189 int t; 190 191 switch (cmd) { 192 case WDIOC_GETSUPPORT: 193 err = copy_to_user(argp, &ath79_wdt_info, 194 sizeof(ath79_wdt_info)) ? -EFAULT : 0; 195 break; 196 197 case WDIOC_GETSTATUS: 198 err = put_user(0, p); 199 break; 200 201 case WDIOC_GETBOOTSTATUS: 202 err = put_user(boot_status, p); 203 break; 204 205 case WDIOC_KEEPALIVE: 206 ath79_wdt_keepalive(); 207 err = 0; 208 break; 209 210 case WDIOC_SETTIMEOUT: 211 err = get_user(t, p); 212 if (err) 213 break; 214 215 err = ath79_wdt_set_timeout(t); 216 if (err) 217 break; 218 fallthrough; 219 220 case WDIOC_GETTIMEOUT: 221 err = put_user(timeout, p); 222 break; 223 224 default: 225 err = -ENOTTY; 226 break; 227 } 228 229 return err; 230 } 231 232 static const struct file_operations ath79_wdt_fops = { 233 .owner = THIS_MODULE, 234 .llseek = no_llseek, 235 .write = ath79_wdt_write, 236 .unlocked_ioctl = ath79_wdt_ioctl, 237 .compat_ioctl = compat_ptr_ioctl, 238 .open = ath79_wdt_open, 239 .release = ath79_wdt_release, 240 }; 241 242 static struct miscdevice ath79_wdt_miscdev = { 243 .minor = WATCHDOG_MINOR, 244 .name = "watchdog", 245 .fops = &ath79_wdt_fops, 246 }; 247 248 static int ath79_wdt_probe(struct platform_device *pdev) 249 { 250 u32 ctrl; 251 int err; 252 253 if (wdt_base) 254 return -EBUSY; 255 256 wdt_base = devm_platform_ioremap_resource(pdev, 0); 257 if (IS_ERR(wdt_base)) 258 return PTR_ERR(wdt_base); 259 260 wdt_clk = devm_clk_get(&pdev->dev, "wdt"); 261 if (IS_ERR(wdt_clk)) 262 return PTR_ERR(wdt_clk); 263 264 err = clk_prepare_enable(wdt_clk); 265 if (err) 266 return err; 267 268 wdt_freq = clk_get_rate(wdt_clk); 269 if (!wdt_freq) { 270 err = -EINVAL; 271 goto err_clk_disable; 272 } 273 274 max_timeout = (0xfffffffful / wdt_freq); 275 if (timeout < 1 || timeout > max_timeout) { 276 timeout = max_timeout; 277 dev_info(&pdev->dev, 278 "timeout value must be 0 < timeout < %d, using %d\n", 279 max_timeout, timeout); 280 } 281 282 ctrl = ath79_wdt_rr(WDOG_REG_CTRL); 283 boot_status = (ctrl & WDOG_CTRL_LAST_RESET) ? WDIOF_CARDRESET : 0; 284 285 err = misc_register(&ath79_wdt_miscdev); 286 if (err) { 287 dev_err(&pdev->dev, 288 "unable to register misc device, err=%d\n", err); 289 goto err_clk_disable; 290 } 291 292 return 0; 293 294 err_clk_disable: 295 clk_disable_unprepare(wdt_clk); 296 return err; 297 } 298 299 static void ath79_wdt_remove(struct platform_device *pdev) 300 { 301 misc_deregister(&ath79_wdt_miscdev); 302 clk_disable_unprepare(wdt_clk); 303 } 304 305 static void ath79_wdt_shutdown(struct platform_device *pdev) 306 { 307 ath79_wdt_disable(); 308 } 309 310 #ifdef CONFIG_OF 311 static const struct of_device_id ath79_wdt_match[] = { 312 { .compatible = "qca,ar7130-wdt" }, 313 {}, 314 }; 315 MODULE_DEVICE_TABLE(of, ath79_wdt_match); 316 #endif 317 318 static struct platform_driver ath79_wdt_driver = { 319 .probe = ath79_wdt_probe, 320 .remove_new = ath79_wdt_remove, 321 .shutdown = ath79_wdt_shutdown, 322 .driver = { 323 .name = DRIVER_NAME, 324 .of_match_table = of_match_ptr(ath79_wdt_match), 325 }, 326 }; 327 328 module_platform_driver(ath79_wdt_driver); 329 330 MODULE_DESCRIPTION("Atheros AR71XX/AR724X/AR913X hardware watchdog driver"); 331 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org"); 332 MODULE_AUTHOR("Imre Kaloz <kaloz@openwrt.org"); 333 MODULE_LICENSE("GPL v2"); 334 MODULE_ALIAS("platform:" DRIVER_NAME); 335