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 dev_info(wdog->dev, "Watchdog timer stopped"); 83 return 0; 84 } 85 86 static int bcm2835_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t) 87 { 88 wdog->timeout = t; 89 return 0; 90 } 91 92 static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog) 93 { 94 struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); 95 96 uint32_t ret = readl_relaxed(wdt->base + PM_WDOG); 97 return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET); 98 } 99 100 static struct watchdog_ops bcm2835_wdt_ops = { 101 .owner = THIS_MODULE, 102 .start = bcm2835_wdt_start, 103 .stop = bcm2835_wdt_stop, 104 .set_timeout = bcm2835_wdt_set_timeout, 105 .get_timeleft = bcm2835_wdt_get_timeleft, 106 }; 107 108 static struct watchdog_info bcm2835_wdt_info = { 109 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | 110 WDIOF_KEEPALIVEPING, 111 .identity = "Broadcom BCM2835 Watchdog timer", 112 }; 113 114 static struct watchdog_device bcm2835_wdt_wdd = { 115 .info = &bcm2835_wdt_info, 116 .ops = &bcm2835_wdt_ops, 117 .min_timeout = 1, 118 .max_timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET), 119 .timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET), 120 }; 121 122 static int 123 bcm2835_restart(struct notifier_block *this, unsigned long mode, void *cmd) 124 { 125 struct bcm2835_wdt *wdt = container_of(this, struct bcm2835_wdt, 126 restart_handler); 127 u32 val; 128 129 /* use a timeout of 10 ticks (~150us) */ 130 writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG); 131 val = readl_relaxed(wdt->base + PM_RSTC); 132 val &= PM_RSTC_WRCFG_CLR; 133 val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET; 134 writel_relaxed(val, wdt->base + PM_RSTC); 135 136 /* No sleeping, possibly atomic. */ 137 mdelay(1); 138 139 return 0; 140 } 141 142 /* 143 * We can't really power off, but if we do the normal reset scheme, and 144 * indicate to bootcode.bin not to reboot, then most of the chip will be 145 * powered off. 146 */ 147 static void bcm2835_power_off(void) 148 { 149 struct device_node *np = 150 of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt"); 151 struct platform_device *pdev = of_find_device_by_node(np); 152 struct bcm2835_wdt *wdt = platform_get_drvdata(pdev); 153 u32 val; 154 155 /* 156 * We set the watchdog hard reset bit here to distinguish this reset 157 * from the normal (full) reset. bootcode.bin will not reboot after a 158 * hard reset. 159 */ 160 val = readl_relaxed(wdt->base + PM_RSTS); 161 val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT; 162 writel_relaxed(val, wdt->base + PM_RSTS); 163 164 /* Continue with normal reset mechanism */ 165 bcm2835_restart(&wdt->restart_handler, REBOOT_HARD, NULL); 166 } 167 168 static int bcm2835_wdt_probe(struct platform_device *pdev) 169 { 170 struct device *dev = &pdev->dev; 171 struct device_node *np = dev->of_node; 172 struct bcm2835_wdt *wdt; 173 int err; 174 175 wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL); 176 if (!wdt) 177 return -ENOMEM; 178 platform_set_drvdata(pdev, wdt); 179 180 spin_lock_init(&wdt->lock); 181 182 wdt->base = of_iomap(np, 0); 183 if (!wdt->base) { 184 dev_err(dev, "Failed to remap watchdog regs"); 185 return -ENODEV; 186 } 187 188 watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt); 189 watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev); 190 watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout); 191 bcm2835_wdt_wdd.parent = &pdev->dev; 192 err = watchdog_register_device(&bcm2835_wdt_wdd); 193 if (err) { 194 dev_err(dev, "Failed to register watchdog device"); 195 iounmap(wdt->base); 196 return err; 197 } 198 199 wdt->restart_handler.notifier_call = bcm2835_restart; 200 wdt->restart_handler.priority = 128; 201 register_restart_handler(&wdt->restart_handler); 202 if (pm_power_off == NULL) 203 pm_power_off = bcm2835_power_off; 204 205 dev_info(dev, "Broadcom BCM2835 watchdog timer"); 206 return 0; 207 } 208 209 static int bcm2835_wdt_remove(struct platform_device *pdev) 210 { 211 struct bcm2835_wdt *wdt = platform_get_drvdata(pdev); 212 213 unregister_restart_handler(&wdt->restart_handler); 214 if (pm_power_off == bcm2835_power_off) 215 pm_power_off = NULL; 216 watchdog_unregister_device(&bcm2835_wdt_wdd); 217 iounmap(wdt->base); 218 219 return 0; 220 } 221 222 static void bcm2835_wdt_shutdown(struct platform_device *pdev) 223 { 224 bcm2835_wdt_stop(&bcm2835_wdt_wdd); 225 } 226 227 static const struct of_device_id bcm2835_wdt_of_match[] = { 228 { .compatible = "brcm,bcm2835-pm-wdt", }, 229 {}, 230 }; 231 MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match); 232 233 static struct platform_driver bcm2835_wdt_driver = { 234 .probe = bcm2835_wdt_probe, 235 .remove = bcm2835_wdt_remove, 236 .shutdown = bcm2835_wdt_shutdown, 237 .driver = { 238 .name = "bcm2835-wdt", 239 .of_match_table = bcm2835_wdt_of_match, 240 }, 241 }; 242 module_platform_driver(bcm2835_wdt_driver); 243 244 module_param(heartbeat, uint, 0); 245 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds"); 246 247 module_param(nowayout, bool, 0); 248 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 249 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 250 251 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>"); 252 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer"); 253 MODULE_LICENSE("GPL"); 254