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