1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Watchdog driver for Broadcom BCM2835 4 * 5 * "bcm2708_wdog" driver written by Luke Diamand that was obtained from 6 * branch "rpi-3.6.y" of git://github.com/raspberrypi/linux.git was used 7 * as a hardware reference for the Broadcom BCM2835 watchdog timer. 8 * 9 * Copyright (C) 2013 Lubomir Rintel <lkundrak@v3.sk> 10 * 11 */ 12 13 #include <linux/delay.h> 14 #include <linux/types.h> 15 #include <linux/mfd/bcm2835-pm.h> 16 #include <linux/module.h> 17 #include <linux/io.h> 18 #include <linux/watchdog.h> 19 #include <linux/platform_device.h> 20 #include <linux/of_address.h> 21 #include <linux/of_platform.h> 22 23 #define PM_RSTC 0x1c 24 #define PM_RSTS 0x20 25 #define PM_WDOG 0x24 26 27 #define PM_PASSWORD 0x5a000000 28 29 #define PM_WDOG_TIME_SET 0x000fffff 30 #define PM_RSTC_WRCFG_CLR 0xffffffcf 31 #define PM_RSTS_HADWRH_SET 0x00000040 32 #define PM_RSTC_WRCFG_SET 0x00000030 33 #define PM_RSTC_WRCFG_FULL_RESET 0x00000020 34 #define PM_RSTC_RESET 0x00000102 35 36 /* 37 * The Raspberry Pi firmware uses the RSTS register to know which partition 38 * to boot from. The partition value is spread into bits 0, 2, 4, 6, 8, 10. 39 * Partition 63 is a special partition used by the firmware to indicate halt. 40 */ 41 #define PM_RSTS_RASPBERRYPI_HALT 0x555 42 43 #define SECS_TO_WDOG_TICKS(x) ((x) << 16) 44 #define WDOG_TICKS_TO_SECS(x) ((x) >> 16) 45 46 struct bcm2835_wdt { 47 void __iomem *base; 48 spinlock_t lock; 49 }; 50 51 static struct bcm2835_wdt *bcm2835_power_off_wdt; 52 53 static unsigned int heartbeat; 54 static bool nowayout = WATCHDOG_NOWAYOUT; 55 56 static bool bcm2835_wdt_is_running(struct bcm2835_wdt *wdt) 57 { 58 uint32_t cur; 59 60 cur = readl(wdt->base + PM_RSTC); 61 62 return !!(cur & PM_RSTC_WRCFG_FULL_RESET); 63 } 64 65 static int bcm2835_wdt_start(struct watchdog_device *wdog) 66 { 67 struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); 68 uint32_t cur; 69 unsigned long flags; 70 71 spin_lock_irqsave(&wdt->lock, flags); 72 73 writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) & 74 PM_WDOG_TIME_SET), wdt->base + PM_WDOG); 75 cur = readl_relaxed(wdt->base + PM_RSTC); 76 writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) | 77 PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC); 78 79 spin_unlock_irqrestore(&wdt->lock, flags); 80 81 return 0; 82 } 83 84 static int bcm2835_wdt_stop(struct watchdog_device *wdog) 85 { 86 struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); 87 88 writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC); 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 void __bcm2835_restart(struct bcm2835_wdt *wdt) 101 { 102 u32 val; 103 104 /* use a timeout of 10 ticks (~150us) */ 105 writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG); 106 val = readl_relaxed(wdt->base + PM_RSTC); 107 val &= PM_RSTC_WRCFG_CLR; 108 val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET; 109 writel_relaxed(val, wdt->base + PM_RSTC); 110 111 /* No sleeping, possibly atomic. */ 112 mdelay(1); 113 } 114 115 static int bcm2835_restart(struct watchdog_device *wdog, 116 unsigned long action, void *data) 117 { 118 struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); 119 120 __bcm2835_restart(wdt); 121 122 return 0; 123 } 124 125 static const struct watchdog_ops bcm2835_wdt_ops = { 126 .owner = THIS_MODULE, 127 .start = bcm2835_wdt_start, 128 .stop = bcm2835_wdt_stop, 129 .get_timeleft = bcm2835_wdt_get_timeleft, 130 .restart = bcm2835_restart, 131 }; 132 133 static const struct watchdog_info bcm2835_wdt_info = { 134 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | 135 WDIOF_KEEPALIVEPING, 136 .identity = "Broadcom BCM2835 Watchdog timer", 137 }; 138 139 static struct watchdog_device bcm2835_wdt_wdd = { 140 .info = &bcm2835_wdt_info, 141 .ops = &bcm2835_wdt_ops, 142 .min_timeout = 1, 143 .max_timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET), 144 .timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET), 145 }; 146 147 /* 148 * We can't really power off, but if we do the normal reset scheme, and 149 * indicate to bootcode.bin not to reboot, then most of the chip will be 150 * powered off. 151 */ 152 static void bcm2835_power_off(void) 153 { 154 struct bcm2835_wdt *wdt = bcm2835_power_off_wdt; 155 u32 val; 156 157 /* 158 * We set the watchdog hard reset bit here to distinguish this reset 159 * from the normal (full) reset. bootcode.bin will not reboot after a 160 * hard reset. 161 */ 162 val = readl_relaxed(wdt->base + PM_RSTS); 163 val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT; 164 writel_relaxed(val, wdt->base + PM_RSTS); 165 166 /* Continue with normal reset mechanism */ 167 __bcm2835_restart(wdt); 168 } 169 170 static int bcm2835_wdt_probe(struct platform_device *pdev) 171 { 172 struct bcm2835_pm *pm = dev_get_drvdata(pdev->dev.parent); 173 struct device *dev = &pdev->dev; 174 struct bcm2835_wdt *wdt; 175 int err; 176 177 wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL); 178 if (!wdt) 179 return -ENOMEM; 180 181 spin_lock_init(&wdt->lock); 182 183 wdt->base = pm->base; 184 185 watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt); 186 watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev); 187 watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout); 188 bcm2835_wdt_wdd.parent = dev; 189 if (bcm2835_wdt_is_running(wdt)) { 190 /* 191 * The currently active timeout value (set by the 192 * bootloader) may be different from the module 193 * heartbeat parameter or the value in device 194 * tree. But we just need to set WDOG_HW_RUNNING, 195 * because then the framework will "immediately" ping 196 * the device, updating the timeout. 197 */ 198 set_bit(WDOG_HW_RUNNING, &bcm2835_wdt_wdd.status); 199 } 200 201 watchdog_set_restart_priority(&bcm2835_wdt_wdd, 128); 202 203 watchdog_stop_on_reboot(&bcm2835_wdt_wdd); 204 err = devm_watchdog_register_device(dev, &bcm2835_wdt_wdd); 205 if (err) 206 return err; 207 208 if (of_device_is_system_power_controller(pdev->dev.parent->of_node)) { 209 if (!pm_power_off) { 210 pm_power_off = bcm2835_power_off; 211 bcm2835_power_off_wdt = wdt; 212 } else { 213 dev_info(dev, "Poweroff handler already present!\n"); 214 } 215 } 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 if (pm_power_off == bcm2835_power_off) 224 pm_power_off = NULL; 225 226 return 0; 227 } 228 229 static struct platform_driver bcm2835_wdt_driver = { 230 .probe = bcm2835_wdt_probe, 231 .remove = bcm2835_wdt_remove, 232 .driver = { 233 .name = "bcm2835-wdt", 234 }, 235 }; 236 module_platform_driver(bcm2835_wdt_driver); 237 238 module_param(heartbeat, uint, 0); 239 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds"); 240 241 module_param(nowayout, bool, 0); 242 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 243 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 244 245 MODULE_ALIAS("platform:bcm2835-wdt"); 246 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>"); 247 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer"); 248 MODULE_LICENSE("GPL"); 249