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/types.h> 17 #include <linux/module.h> 18 #include <linux/io.h> 19 #include <linux/watchdog.h> 20 #include <linux/platform_device.h> 21 #include <linux/of_address.h> 22 #include <linux/miscdevice.h> 23 24 #define PM_RSTC 0x1c 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_RSTC_WRCFG_SET 0x00000030 32 #define PM_RSTC_WRCFG_FULL_RESET 0x00000020 33 #define PM_RSTC_RESET 0x00000102 34 35 #define SECS_TO_WDOG_TICKS(x) ((x) << 16) 36 #define WDOG_TICKS_TO_SECS(x) ((x) >> 16) 37 38 struct bcm2835_wdt { 39 void __iomem *base; 40 spinlock_t lock; 41 }; 42 43 static unsigned int heartbeat; 44 static bool nowayout = WATCHDOG_NOWAYOUT; 45 46 static int bcm2835_wdt_start(struct watchdog_device *wdog) 47 { 48 struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); 49 uint32_t cur; 50 unsigned long flags; 51 52 spin_lock_irqsave(&wdt->lock, flags); 53 54 writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) & 55 PM_WDOG_TIME_SET), wdt->base + PM_WDOG); 56 cur = readl_relaxed(wdt->base + PM_RSTC); 57 writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) | 58 PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC); 59 60 spin_unlock_irqrestore(&wdt->lock, flags); 61 62 return 0; 63 } 64 65 static int bcm2835_wdt_stop(struct watchdog_device *wdog) 66 { 67 struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); 68 69 writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC); 70 dev_info(wdog->dev, "Watchdog timer stopped"); 71 return 0; 72 } 73 74 static int bcm2835_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t) 75 { 76 wdog->timeout = t; 77 return 0; 78 } 79 80 static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog) 81 { 82 struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog); 83 84 uint32_t ret = readl_relaxed(wdt->base + PM_WDOG); 85 return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET); 86 } 87 88 static struct watchdog_ops bcm2835_wdt_ops = { 89 .owner = THIS_MODULE, 90 .start = bcm2835_wdt_start, 91 .stop = bcm2835_wdt_stop, 92 .set_timeout = bcm2835_wdt_set_timeout, 93 .get_timeleft = bcm2835_wdt_get_timeleft, 94 }; 95 96 static struct watchdog_info bcm2835_wdt_info = { 97 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | 98 WDIOF_KEEPALIVEPING, 99 .identity = "Broadcom BCM2835 Watchdog timer", 100 }; 101 102 static struct watchdog_device bcm2835_wdt_wdd = { 103 .info = &bcm2835_wdt_info, 104 .ops = &bcm2835_wdt_ops, 105 .min_timeout = 1, 106 .max_timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET), 107 .timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET), 108 }; 109 110 static int bcm2835_wdt_probe(struct platform_device *pdev) 111 { 112 struct device *dev = &pdev->dev; 113 struct device_node *np = dev->of_node; 114 struct bcm2835_wdt *wdt; 115 int err; 116 117 wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL); 118 if (!wdt) { 119 dev_err(dev, "Failed to allocate memory for watchdog device"); 120 return -ENOMEM; 121 } 122 platform_set_drvdata(pdev, wdt); 123 124 spin_lock_init(&wdt->lock); 125 126 wdt->base = of_iomap(np, 0); 127 if (!wdt->base) { 128 dev_err(dev, "Failed to remap watchdog regs"); 129 return -ENODEV; 130 } 131 132 watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt); 133 watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev); 134 watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout); 135 err = watchdog_register_device(&bcm2835_wdt_wdd); 136 if (err) { 137 dev_err(dev, "Failed to register watchdog device"); 138 iounmap(wdt->base); 139 return err; 140 } 141 142 dev_info(dev, "Broadcom BCM2835 watchdog timer"); 143 return 0; 144 } 145 146 static int bcm2835_wdt_remove(struct platform_device *pdev) 147 { 148 struct bcm2835_wdt *wdt = platform_get_drvdata(pdev); 149 150 watchdog_unregister_device(&bcm2835_wdt_wdd); 151 iounmap(wdt->base); 152 153 return 0; 154 } 155 156 static void bcm2835_wdt_shutdown(struct platform_device *pdev) 157 { 158 bcm2835_wdt_stop(&bcm2835_wdt_wdd); 159 } 160 161 static const struct of_device_id bcm2835_wdt_of_match[] = { 162 { .compatible = "brcm,bcm2835-pm-wdt", }, 163 {}, 164 }; 165 MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match); 166 167 static struct platform_driver bcm2835_wdt_driver = { 168 .probe = bcm2835_wdt_probe, 169 .remove = bcm2835_wdt_remove, 170 .shutdown = bcm2835_wdt_shutdown, 171 .driver = { 172 .name = "bcm2835-wdt", 173 .owner = THIS_MODULE, 174 .of_match_table = bcm2835_wdt_of_match, 175 }, 176 }; 177 module_platform_driver(bcm2835_wdt_driver); 178 179 module_param(heartbeat, uint, 0); 180 MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds"); 181 182 module_param(nowayout, bool, 0); 183 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 184 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 185 186 MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>"); 187 MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer"); 188 MODULE_LICENSE("GPL"); 189 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 190