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 int bcm2835_wdt_start(struct watchdog_device *wdog) 59 { 60 struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); 61 uint32_t cur; 62 unsigned long flags; 63 64 spin_lock_irqsave(&wdt->lock, flags); 65 66 writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) & 67 PM_WDOG_TIME_SET), wdt->base + PM_WDOG); 68 cur = readl_relaxed(wdt->base + PM_RSTC); 69 writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) | 70 PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC); 71 72 spin_unlock_irqrestore(&wdt->lock, flags); 73 74 return 0; 75 } 76 77 static int bcm2835_wdt_stop(struct watchdog_device *wdog) 78 { 79 struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); 80 81 writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC); 82 return 0; 83 } 84 85 static int bcm2835_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t) 86 { 87 wdog->timeout = t; 88 return 0; 89 } 90 91 static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog) 92 { 93 struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); 94 95 uint32_t ret = readl_relaxed(wdt->base + PM_WDOG); 96 return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET); 97 } 98 99 static struct watchdog_ops bcm2835_wdt_ops = { 100 .owner = THIS_MODULE, 101 .start = bcm2835_wdt_start, 102 .stop = bcm2835_wdt_stop, 103 .set_timeout = bcm2835_wdt_set_timeout, 104 .get_timeleft = bcm2835_wdt_get_timeleft, 105 }; 106 107 static struct watchdog_info bcm2835_wdt_info = { 108 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | 109 WDIOF_KEEPALIVEPING, 110 .identity = "Broadcom BCM2835 Watchdog timer", 111 }; 112 113 static struct watchdog_device bcm2835_wdt_wdd = { 114 .info = &bcm2835_wdt_info, 115 .ops = &bcm2835_wdt_ops, 116 .min_timeout = 1, 117 .max_timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET), 118 .timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET), 119 }; 120 121 static int 122 bcm2835_restart(struct notifier_block *this, unsigned long mode, void *cmd) 123 { 124 struct bcm2835_wdt *wdt = container_of(this, struct bcm2835_wdt, 125 restart_handler); 126 u32 val; 127 128 /* use a timeout of 10 ticks (~150us) */ 129 writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG); 130 val = readl_relaxed(wdt->base + PM_RSTC); 131 val &= PM_RSTC_WRCFG_CLR; 132 val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET; 133 writel_relaxed(val, wdt->base + PM_RSTC); 134 135 /* No sleeping, possibly atomic. */ 136 mdelay(1); 137 138 return 0; 139 } 140 141 /* 142 * We can't really power off, but if we do the normal reset scheme, and 143 * indicate to bootcode.bin not to reboot, then most of the chip will be 144 * powered off. 145 */ 146 static void bcm2835_power_off(void) 147 { 148 struct device_node *np = 149 of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt"); 150 struct platform_device *pdev = of_find_device_by_node(np); 151 struct bcm2835_wdt *wdt = platform_get_drvdata(pdev); 152 u32 val; 153 154 /* 155 * We set the watchdog hard reset bit here to distinguish this reset 156 * from the normal (full) reset. bootcode.bin will not reboot after a 157 * hard reset. 158 */ 159 val = readl_relaxed(wdt->base + PM_RSTS); 160 val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT; 161 writel_relaxed(val, wdt->base + PM_RSTS); 162 163 /* Continue with normal reset mechanism */ 164 bcm2835_restart(&wdt->restart_handler, REBOOT_HARD, NULL); 165 } 166 167 static int bcm2835_wdt_probe(struct platform_device *pdev) 168 { 169 struct device *dev = &pdev->dev; 170 struct device_node *np = dev->of_node; 171 struct bcm2835_wdt *wdt; 172 int err; 173 174 wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL); 175 if (!wdt) 176 return -ENOMEM; 177 platform_set_drvdata(pdev, wdt); 178 179 spin_lock_init(&wdt->lock); 180 181 wdt->base = of_iomap(np, 0); 182 if (!wdt->base) { 183 dev_err(dev, "Failed to remap watchdog regs"); 184 return -ENODEV; 185 } 186 187 watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt); 188 watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev); 189 watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout); 190 bcm2835_wdt_wdd.parent = &pdev->dev; 191 err = watchdog_register_device(&bcm2835_wdt_wdd); 192 if (err) { 193 dev_err(dev, "Failed to register watchdog device"); 194 iounmap(wdt->base); 195 return err; 196 } 197 198 wdt->restart_handler.notifier_call = bcm2835_restart; 199 wdt->restart_handler.priority = 128; 200 register_restart_handler(&wdt->restart_handler); 201 if (pm_power_off == NULL) 202 pm_power_off = bcm2835_power_off; 203 204 dev_info(dev, "Broadcom BCM2835 watchdog timer"); 205 return 0; 206 } 207 208 static int bcm2835_wdt_remove(struct platform_device *pdev) 209 { 210 struct bcm2835_wdt *wdt = platform_get_drvdata(pdev); 211 212 unregister_restart_handler(&wdt->restart_handler); 213 if (pm_power_off == bcm2835_power_off) 214 pm_power_off = NULL; 215 watchdog_unregister_device(&bcm2835_wdt_wdd); 216 iounmap(wdt->base); 217 218 return 0; 219 } 220 221 static void bcm2835_wdt_shutdown(struct platform_device *pdev) 222 { 223 bcm2835_wdt_stop(&bcm2835_wdt_wdd); 224 } 225 226 static const struct of_device_id bcm2835_wdt_of_match[] = { 227 { .compatible = "brcm,bcm2835-pm-wdt", }, 228 {}, 229 }; 230 MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match); 231 232 static struct platform_driver bcm2835_wdt_driver = { 233 .probe = bcm2835_wdt_probe, 234 .remove = bcm2835_wdt_remove, 235 .shutdown = bcm2835_wdt_shutdown, 236 .driver = { 237 .name = "bcm2835-wdt", 238 .of_match_table = bcm2835_wdt_of_match, 239 }, 240 }; 241 module_platform_driver(bcm2835_wdt_driver); 242 243 module_param(heartbeat, uint, 0); 244 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds"); 245 246 module_param(nowayout, bool, 0); 247 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 248 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 249 250 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>"); 251 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer"); 252 MODULE_LICENSE("GPL"); 253