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Linux/drivers/watchdog/imx2_wdt.c

  1 /*
  2  * Watchdog driver for IMX2 and later processors
  3  *
  4  *  Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <w.sang@pengutronix.de>
  5  *  Copyright (C) 2014 Freescale Semiconductor, Inc.
  6  *
  7  * some parts adapted by similar drivers from Darius Augulis and Vladimir
  8  * Zapolskiy, additional improvements by Wim Van Sebroeck.
  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 version 2 as published by
 12  * the Free Software Foundation.
 13  *
 14  * NOTE: MX1 has a slightly different Watchdog than MX2 and later:
 15  *
 16  *                      MX1:            MX2+:
 17  *                      ----            -----
 18  * Registers:           32-bit          16-bit
 19  * Stopable timer:      Yes             No
 20  * Need to enable clk:  No              Yes
 21  * Halt on suspend:     Manual          Can be automatic
 22  */
 23 
 24 #include <linux/clk.h>
 25 #include <linux/init.h>
 26 #include <linux/io.h>
 27 #include <linux/jiffies.h>
 28 #include <linux/kernel.h>
 29 #include <linux/module.h>
 30 #include <linux/moduleparam.h>
 31 #include <linux/platform_device.h>
 32 #include <linux/regmap.h>
 33 #include <linux/timer.h>
 34 #include <linux/watchdog.h>
 35 
 36 #define DRIVER_NAME "imx2-wdt"
 37 
 38 #define IMX2_WDT_WCR            0x00            /* Control Register */
 39 #define IMX2_WDT_WCR_WT         (0xFF << 8)     /* -> Watchdog Timeout Field */
 40 #define IMX2_WDT_WCR_WRE        (1 << 3)        /* -> WDOG Reset Enable */
 41 #define IMX2_WDT_WCR_WDE        (1 << 2)        /* -> Watchdog Enable */
 42 #define IMX2_WDT_WCR_WDZST      (1 << 0)        /* -> Watchdog timer Suspend */
 43 
 44 #define IMX2_WDT_WSR            0x02            /* Service Register */
 45 #define IMX2_WDT_SEQ1           0x5555          /* -> service sequence 1 */
 46 #define IMX2_WDT_SEQ2           0xAAAA          /* -> service sequence 2 */
 47 
 48 #define IMX2_WDT_WRSR           0x04            /* Reset Status Register */
 49 #define IMX2_WDT_WRSR_TOUT      (1 << 1)        /* -> Reset due to Timeout */
 50 
 51 #define IMX2_WDT_MAX_TIME       128
 52 #define IMX2_WDT_DEFAULT_TIME   60              /* in seconds */
 53 
 54 #define WDOG_SEC_TO_COUNT(s)    ((s * 2 - 1) << 8)
 55 
 56 struct imx2_wdt_device {
 57         struct clk *clk;
 58         struct regmap *regmap;
 59         struct timer_list timer;        /* Pings the watchdog when closed */
 60         struct watchdog_device wdog;
 61 };
 62 
 63 static bool nowayout = WATCHDOG_NOWAYOUT;
 64 module_param(nowayout, bool, 0);
 65 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 66                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 67 
 68 
 69 static unsigned timeout = IMX2_WDT_DEFAULT_TIME;
 70 module_param(timeout, uint, 0);
 71 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
 72                                 __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
 73 
 74 static const struct watchdog_info imx2_wdt_info = {
 75         .identity = "imx2+ watchdog",
 76         .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 77 };
 78 
 79 static inline void imx2_wdt_setup(struct watchdog_device *wdog)
 80 {
 81         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 82         u32 val;
 83 
 84         regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
 85 
 86         /* Suspend timer in low power mode, write once-only */
 87         val |= IMX2_WDT_WCR_WDZST;
 88         /* Strip the old watchdog Time-Out value */
 89         val &= ~IMX2_WDT_WCR_WT;
 90         /* Generate reset if WDOG times out */
 91         val &= ~IMX2_WDT_WCR_WRE;
 92         /* Keep Watchdog Disabled */
 93         val &= ~IMX2_WDT_WCR_WDE;
 94         /* Set the watchdog's Time-Out value */
 95         val |= WDOG_SEC_TO_COUNT(wdog->timeout);
 96 
 97         regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
 98 
 99         /* enable the watchdog */
100         val |= IMX2_WDT_WCR_WDE;
101         regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
102 }
103 
104 static inline bool imx2_wdt_is_running(struct imx2_wdt_device *wdev)
105 {
106         u32 val;
107 
108         regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
109 
110         return val & IMX2_WDT_WCR_WDE;
111 }
112 
113 static int imx2_wdt_ping(struct watchdog_device *wdog)
114 {
115         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
116 
117         regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ1);
118         regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ2);
119         return 0;
120 }
121 
122 static void imx2_wdt_timer_ping(unsigned long arg)
123 {
124         struct watchdog_device *wdog = (struct watchdog_device *)arg;
125         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
126 
127         /* ping it every wdog->timeout / 2 seconds to prevent reboot */
128         imx2_wdt_ping(wdog);
129         mod_timer(&wdev->timer, jiffies + wdog->timeout * HZ / 2);
130 }
131 
132 static int imx2_wdt_set_timeout(struct watchdog_device *wdog,
133                                 unsigned int new_timeout)
134 {
135         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
136 
137         regmap_update_bits(wdev->regmap, IMX2_WDT_WCR, IMX2_WDT_WCR_WT,
138                            WDOG_SEC_TO_COUNT(new_timeout));
139         return 0;
140 }
141 
142 static int imx2_wdt_start(struct watchdog_device *wdog)
143 {
144         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
145 
146         if (imx2_wdt_is_running(wdev)) {
147                 /* delete the timer that pings the watchdog after close */
148                 del_timer_sync(&wdev->timer);
149                 imx2_wdt_set_timeout(wdog, wdog->timeout);
150         } else
151                 imx2_wdt_setup(wdog);
152 
153         return imx2_wdt_ping(wdog);
154 }
155 
156 static int imx2_wdt_stop(struct watchdog_device *wdog)
157 {
158         /*
159          * We don't need a clk_disable, it cannot be disabled once started.
160          * We use a timer to ping the watchdog while /dev/watchdog is closed
161          */
162         imx2_wdt_timer_ping((unsigned long)wdog);
163         return 0;
164 }
165 
166 static inline void imx2_wdt_ping_if_active(struct watchdog_device *wdog)
167 {
168         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
169 
170         if (imx2_wdt_is_running(wdev)) {
171                 imx2_wdt_set_timeout(wdog, wdog->timeout);
172                 imx2_wdt_timer_ping((unsigned long)wdog);
173         }
174 }
175 
176 static struct watchdog_ops imx2_wdt_ops = {
177         .owner = THIS_MODULE,
178         .start = imx2_wdt_start,
179         .stop = imx2_wdt_stop,
180         .ping = imx2_wdt_ping,
181         .set_timeout = imx2_wdt_set_timeout,
182 };
183 
184 static struct regmap_config imx2_wdt_regmap_config = {
185         .reg_bits = 16,
186         .reg_stride = 2,
187         .val_bits = 16,
188         .max_register = 0x8,
189 };
190 
191 static int __init imx2_wdt_probe(struct platform_device *pdev)
192 {
193         struct imx2_wdt_device *wdev;
194         struct watchdog_device *wdog;
195         struct resource *res;
196         void __iomem *base;
197         int ret;
198         u32 val;
199 
200         wdev = devm_kzalloc(&pdev->dev, sizeof(*wdev), GFP_KERNEL);
201         if (!wdev)
202                 return -ENOMEM;
203 
204         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
205         base = devm_ioremap_resource(&pdev->dev, res);
206         if (IS_ERR(base))
207                 return PTR_ERR(base);
208 
209         wdev->regmap = devm_regmap_init_mmio_clk(&pdev->dev, NULL, base,
210                                                  &imx2_wdt_regmap_config);
211         if (IS_ERR(wdev->regmap)) {
212                 dev_err(&pdev->dev, "regmap init failed\n");
213                 return PTR_ERR(wdev->regmap);
214         }
215 
216         wdev->clk = devm_clk_get(&pdev->dev, NULL);
217         if (IS_ERR(wdev->clk)) {
218                 dev_err(&pdev->dev, "can't get Watchdog clock\n");
219                 return PTR_ERR(wdev->clk);
220         }
221 
222         wdog                    = &wdev->wdog;
223         wdog->info              = &imx2_wdt_info;
224         wdog->ops               = &imx2_wdt_ops;
225         wdog->min_timeout       = 1;
226         wdog->max_timeout       = IMX2_WDT_MAX_TIME;
227 
228         clk_prepare_enable(wdev->clk);
229 
230         regmap_read(wdev->regmap, IMX2_WDT_WRSR, &val);
231         wdog->bootstatus = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
232 
233         wdog->timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
234         if (wdog->timeout != timeout)
235                 dev_warn(&pdev->dev, "Initial timeout out of range! Clamped from %u to %u\n",
236                          timeout, wdog->timeout);
237 
238         platform_set_drvdata(pdev, wdog);
239         watchdog_set_drvdata(wdog, wdev);
240         watchdog_set_nowayout(wdog, nowayout);
241         watchdog_init_timeout(wdog, timeout, &pdev->dev);
242 
243         setup_timer(&wdev->timer, imx2_wdt_timer_ping, (unsigned long)wdog);
244 
245         imx2_wdt_ping_if_active(wdog);
246 
247         ret = watchdog_register_device(wdog);
248         if (ret) {
249                 dev_err(&pdev->dev, "cannot register watchdog device\n");
250                 return ret;
251         }
252 
253         dev_info(&pdev->dev, "timeout %d sec (nowayout=%d)\n",
254                  wdog->timeout, nowayout);
255 
256         return 0;
257 }
258 
259 static int __exit imx2_wdt_remove(struct platform_device *pdev)
260 {
261         struct watchdog_device *wdog = platform_get_drvdata(pdev);
262         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
263 
264         watchdog_unregister_device(wdog);
265 
266         if (imx2_wdt_is_running(wdev)) {
267                 del_timer_sync(&wdev->timer);
268                 imx2_wdt_ping(wdog);
269                 dev_crit(&pdev->dev, "Device removed: Expect reboot!\n");
270         }
271         return 0;
272 }
273 
274 static void imx2_wdt_shutdown(struct platform_device *pdev)
275 {
276         struct watchdog_device *wdog = platform_get_drvdata(pdev);
277         struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
278 
279         if (imx2_wdt_is_running(wdev)) {
280                 /*
281                  * We are running, we need to delete the timer but will
282                  * give max timeout before reboot will take place
283                  */
284                 del_timer_sync(&wdev->timer);
285                 imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
286                 imx2_wdt_ping(wdog);
287                 dev_crit(&pdev->dev, "Device shutdown: Expect reboot!\n");
288         }
289 }
290 
291 static const struct of_device_id imx2_wdt_dt_ids[] = {
292         { .compatible = "fsl,imx21-wdt", },
293         { /* sentinel */ }
294 };
295 MODULE_DEVICE_TABLE(of, imx2_wdt_dt_ids);
296 
297 static struct platform_driver imx2_wdt_driver = {
298         .remove         = __exit_p(imx2_wdt_remove),
299         .shutdown       = imx2_wdt_shutdown,
300         .driver         = {
301                 .name   = DRIVER_NAME,
302                 .owner  = THIS_MODULE,
303                 .of_match_table = imx2_wdt_dt_ids,
304         },
305 };
306 
307 module_platform_driver_probe(imx2_wdt_driver, imx2_wdt_probe);
308 
309 MODULE_AUTHOR("Wolfram Sang");
310 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
311 MODULE_LICENSE("GPL v2");
312 MODULE_ALIAS("platform:" DRIVER_NAME);
313 

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