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Linux/drivers/watchdog/bcm2835_wdt.c

  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 

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