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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         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 

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