1 /* 2 * Watchdog driver for Broadcom BCM2835 3 * 4 * "bcm2708_wdog" driver written by Luke Diamand that was obtained from 5 * branch "rpi-3.6.y" of git://github.com/raspberrypi/linux.git was used 6 * as a hardware reference for the Broadcom BCM2835 watchdog timer. 7 * 8 * Copyright (C) 2013 Lubomir Rintel <lkundrak@v3.sk> 9 * 10 * This program is free software; you can redistribute it and/or modify it 11 * under the terms of the GNU General Public License as published by the 12 * Free Software Foundation; either version 2 of the License, or (at your 13 * option) any later version. 14 */ 15 16 #include <linux/delay.h> 17 #include <linux/reboot.h> 18 #include <linux/types.h> 19 #include <linux/module.h> 20 #include <linux/io.h> 21 #include <linux/watchdog.h> 22 #include <linux/platform_device.h> 23 #include <linux/of_address.h> 24 #include <linux/of_platform.h> 25 26 #define PM_RSTC 0x1c 27 #define PM_RSTS 0x20 28 #define PM_WDOG 0x24 29 30 #define PM_PASSWORD 0x5a000000 31 32 #define PM_WDOG_TIME_SET 0x000fffff 33 #define PM_RSTC_WRCFG_CLR 0xffffffcf 34 #define PM_RSTS_HADWRH_SET 0x00000040 35 #define PM_RSTC_WRCFG_SET 0x00000030 36 #define PM_RSTC_WRCFG_FULL_RESET 0x00000020 37 #define PM_RSTC_RESET 0x00000102 38 39 /* 40 * The Raspberry Pi firmware uses the RSTS register to know which partiton 41 * to boot from. The partiton value is spread into bits 0, 2, 4, 6, 8, 10. 42 * Partiton 63 is a special partition used by the firmware to indicate halt. 43 */ 44 #define PM_RSTS_RASPBERRYPI_HALT 0x555 45 46 #define SECS_TO_WDOG_TICKS(x) ((x) << 16) 47 #define WDOG_TICKS_TO_SECS(x) ((x) >> 16) 48 49 struct bcm2835_wdt { 50 void __iomem *base; 51 spinlock_t lock; 52 struct notifier_block restart_handler; 53 }; 54 55 static unsigned int heartbeat; 56 static bool nowayout = WATCHDOG_NOWAYOUT; 57 58 static bool bcm2835_wdt_is_running(struct bcm2835_wdt *wdt) 59 { 60 uint32_t cur; 61 62 cur = readl(wdt->base + PM_RSTC); 63 64 return !!(cur & PM_RSTC_WRCFG_FULL_RESET); 65 } 66 67 static int bcm2835_wdt_start(struct watchdog_device *wdog) 68 { 69 struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); 70 uint32_t cur; 71 unsigned long flags; 72 73 spin_lock_irqsave(&wdt->lock, flags); 74 75 writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) & 76 PM_WDOG_TIME_SET), wdt->base + PM_WDOG); 77 cur = readl_relaxed(wdt->base + PM_RSTC); 78 writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) | 79 PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC); 80 81 spin_unlock_irqrestore(&wdt->lock, flags); 82 83 return 0; 84 } 85 86 static int bcm2835_wdt_stop(struct watchdog_device *wdog) 87 { 88 struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); 89 90 writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC); 91 return 0; 92 } 93 94 static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog) 95 { 96 struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); 97 98 uint32_t ret = readl_relaxed(wdt->base + PM_WDOG); 99 return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET); 100 } 101 102 static const struct watchdog_ops bcm2835_wdt_ops = { 103 .owner = THIS_MODULE, 104 .start = bcm2835_wdt_start, 105 .stop = bcm2835_wdt_stop, 106 .get_timeleft = bcm2835_wdt_get_timeleft, 107 }; 108 109 static const struct watchdog_info bcm2835_wdt_info = { 110 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | 111 WDIOF_KEEPALIVEPING, 112 .identity = "Broadcom BCM2835 Watchdog timer", 113 }; 114 115 static struct watchdog_device bcm2835_wdt_wdd = { 116 .info = &bcm2835_wdt_info, 117 .ops = &bcm2835_wdt_ops, 118 .min_timeout = 1, 119 .max_timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET), 120 .timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET), 121 }; 122 123 static int 124 bcm2835_restart(struct notifier_block *this, unsigned long mode, void *cmd) 125 { 126 struct bcm2835_wdt *wdt = container_of(this, struct bcm2835_wdt, 127 restart_handler); 128 u32 val; 129 130 /* use a timeout of 10 ticks (~150us) */ 131 writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG); 132 val = readl_relaxed(wdt->base + PM_RSTC); 133 val &= PM_RSTC_WRCFG_CLR; 134 val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET; 135 writel_relaxed(val, wdt->base + PM_RSTC); 136 137 /* No sleeping, possibly atomic. */ 138 mdelay(1); 139 140 return 0; 141 } 142 143 /* 144 * We can't really power off, but if we do the normal reset scheme, and 145 * indicate to bootcode.bin not to reboot, then most of the chip will be 146 * powered off. 147 */ 148 static void bcm2835_power_off(void) 149 { 150 struct device_node *np = 151 of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt"); 152 struct platform_device *pdev = of_find_device_by_node(np); 153 struct bcm2835_wdt *wdt = platform_get_drvdata(pdev); 154 u32 val; 155 156 /* 157 * We set the watchdog hard reset bit here to distinguish this reset 158 * from the normal (full) reset. bootcode.bin will not reboot after a 159 * hard reset. 160 */ 161 val = readl_relaxed(wdt->base + PM_RSTS); 162 val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT; 163 writel_relaxed(val, wdt->base + PM_RSTS); 164 165 /* Continue with normal reset mechanism */ 166 bcm2835_restart(&wdt->restart_handler, REBOOT_HARD, NULL); 167 } 168 169 static int bcm2835_wdt_probe(struct platform_device *pdev) 170 { 171 struct device *dev = &pdev->dev; 172 struct device_node *np = dev->of_node; 173 struct bcm2835_wdt *wdt; 174 int err; 175 176 wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL); 177 if (!wdt) 178 return -ENOMEM; 179 platform_set_drvdata(pdev, wdt); 180 181 spin_lock_init(&wdt->lock); 182 183 wdt->base = of_iomap(np, 0); 184 if (!wdt->base) { 185 dev_err(dev, "Failed to remap watchdog regs"); 186 return -ENODEV; 187 } 188 189 watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt); 190 watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev); 191 watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout); 192 bcm2835_wdt_wdd.parent = &pdev->dev; 193 if (bcm2835_wdt_is_running(wdt)) { 194 /* 195 * The currently active timeout value (set by the 196 * bootloader) may be different from the module 197 * heartbeat parameter or the value in device 198 * tree. But we just need to set WDOG_HW_RUNNING, 199 * because then the framework will "immediately" ping 200 * the device, updating the timeout. 201 */ 202 set_bit(WDOG_HW_RUNNING, &bcm2835_wdt_wdd.status); 203 } 204 err = watchdog_register_device(&bcm2835_wdt_wdd); 205 if (err) { 206 dev_err(dev, "Failed to register watchdog device"); 207 iounmap(wdt->base); 208 return err; 209 } 210 211 wdt->restart_handler.notifier_call = bcm2835_restart; 212 wdt->restart_handler.priority = 128; 213 register_restart_handler(&wdt->restart_handler); 214 if (pm_power_off == NULL) 215 pm_power_off = bcm2835_power_off; 216 217 dev_info(dev, "Broadcom BCM2835 watchdog timer"); 218 return 0; 219 } 220 221 static int bcm2835_wdt_remove(struct platform_device *pdev) 222 { 223 struct bcm2835_wdt *wdt = platform_get_drvdata(pdev); 224 225 unregister_restart_handler(&wdt->restart_handler); 226 if (pm_power_off == bcm2835_power_off) 227 pm_power_off = NULL; 228 watchdog_unregister_device(&bcm2835_wdt_wdd); 229 iounmap(wdt->base); 230 231 return 0; 232 } 233 234 static void bcm2835_wdt_shutdown(struct platform_device *pdev) 235 { 236 bcm2835_wdt_stop(&bcm2835_wdt_wdd); 237 } 238 239 static const struct of_device_id bcm2835_wdt_of_match[] = { 240 { .compatible = "brcm,bcm2835-pm-wdt", }, 241 {}, 242 }; 243 MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match); 244 245 static struct platform_driver bcm2835_wdt_driver = { 246 .probe = bcm2835_wdt_probe, 247 .remove = bcm2835_wdt_remove, 248 .shutdown = bcm2835_wdt_shutdown, 249 .driver = { 250 .name = "bcm2835-wdt", 251 .of_match_table = bcm2835_wdt_of_match, 252 }, 253 }; 254 module_platform_driver(bcm2835_wdt_driver); 255 256 module_param(heartbeat, uint, 0); 257 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds"); 258 259 module_param(nowayout, bool, 0); 260 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 261 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 262 263 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>"); 264 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer"); 265 MODULE_LICENSE("GPL"); 266