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Linux/drivers/watchdog/dw_wdt.c

  1 /*
  2  * Copyright 2010-2011 Picochip Ltd., Jamie Iles
  3  * http://www.picochip.com
  4  *
  5  * This program is free software; you can redistribute it and/or
  6  * modify it under the terms of the GNU General Public License
  7  * as published by the Free Software Foundation; either version
  8  * 2 of the License, or (at your option) any later version.
  9  *
 10  * This file implements a driver for the Synopsys DesignWare watchdog device
 11  * in the many subsystems. The watchdog has 16 different timeout periods
 12  * and these are a function of the input clock frequency.
 13  *
 14  * The DesignWare watchdog cannot be stopped once it has been started so we
 15  * do not implement a stop function. The watchdog core will continue to send
 16  * heartbeat requests after the watchdog device has been closed.
 17  */
 18 
 19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 20 
 21 #include <linux/bitops.h>
 22 #include <linux/clk.h>
 23 #include <linux/delay.h>
 24 #include <linux/err.h>
 25 #include <linux/io.h>
 26 #include <linux/kernel.h>
 27 #include <linux/module.h>
 28 #include <linux/moduleparam.h>
 29 #include <linux/notifier.h>
 30 #include <linux/of.h>
 31 #include <linux/pm.h>
 32 #include <linux/platform_device.h>
 33 #include <linux/reboot.h>
 34 #include <linux/watchdog.h>
 35 
 36 #define WDOG_CONTROL_REG_OFFSET             0x00
 37 #define WDOG_CONTROL_REG_WDT_EN_MASK        0x01
 38 #define WDOG_TIMEOUT_RANGE_REG_OFFSET       0x04
 39 #define WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT    4
 40 #define WDOG_CURRENT_COUNT_REG_OFFSET       0x08
 41 #define WDOG_COUNTER_RESTART_REG_OFFSET     0x0c
 42 #define WDOG_COUNTER_RESTART_KICK_VALUE     0x76
 43 
 44 /* The maximum TOP (timeout period) value that can be set in the watchdog. */
 45 #define DW_WDT_MAX_TOP          15
 46 
 47 #define DW_WDT_DEFAULT_SECONDS  30
 48 
 49 static bool nowayout = WATCHDOG_NOWAYOUT;
 50 module_param(nowayout, bool, 0);
 51 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
 52                  "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 53 
 54 struct dw_wdt {
 55         void __iomem            *regs;
 56         struct clk              *clk;
 57         unsigned long           rate;
 58         struct notifier_block   restart_handler;
 59         struct watchdog_device  wdd;
 60 };
 61 
 62 #define to_dw_wdt(wdd)  container_of(wdd, struct dw_wdt, wdd)
 63 
 64 static inline int dw_wdt_is_enabled(struct dw_wdt *dw_wdt)
 65 {
 66         return readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET) &
 67                 WDOG_CONTROL_REG_WDT_EN_MASK;
 68 }
 69 
 70 static inline int dw_wdt_top_in_seconds(struct dw_wdt *dw_wdt, unsigned top)
 71 {
 72         /*
 73          * There are 16 possible timeout values in 0..15 where the number of
 74          * cycles is 2 ^ (16 + i) and the watchdog counts down.
 75          */
 76         return (1U << (16 + top)) / dw_wdt->rate;
 77 }
 78 
 79 static int dw_wdt_get_top(struct dw_wdt *dw_wdt)
 80 {
 81         int top = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
 82 
 83         return dw_wdt_top_in_seconds(dw_wdt, top);
 84 }
 85 
 86 static int dw_wdt_ping(struct watchdog_device *wdd)
 87 {
 88         struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
 89 
 90         writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt->regs +
 91                WDOG_COUNTER_RESTART_REG_OFFSET);
 92 
 93         return 0;
 94 }
 95 
 96 static int dw_wdt_set_timeout(struct watchdog_device *wdd, unsigned int top_s)
 97 {
 98         struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
 99         int i, top_val = DW_WDT_MAX_TOP;
100 
101         /*
102          * Iterate over the timeout values until we find the closest match. We
103          * always look for >=.
104          */
105         for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
106                 if (dw_wdt_top_in_seconds(dw_wdt, i) >= top_s) {
107                         top_val = i;
108                         break;
109                 }
110 
111         /*
112          * Set the new value in the watchdog.  Some versions of dw_wdt
113          * have have TOPINIT in the TIMEOUT_RANGE register (as per
114          * CP_WDT_DUAL_TOP in WDT_COMP_PARAMS_1).  On those we
115          * effectively get a pat of the watchdog right here.
116          */
117         writel(top_val | top_val << WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT,
118                dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
119 
120         wdd->timeout = dw_wdt_top_in_seconds(dw_wdt, top_val);
121 
122         return 0;
123 }
124 
125 static int dw_wdt_start(struct watchdog_device *wdd)
126 {
127         struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
128 
129         dw_wdt_set_timeout(wdd, wdd->timeout);
130 
131         set_bit(WDOG_HW_RUNNING, &wdd->status);
132 
133         writel(WDOG_CONTROL_REG_WDT_EN_MASK,
134                dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
135 
136         return 0;
137 }
138 
139 static int dw_wdt_restart_handle(struct notifier_block *this,
140                                  unsigned long mode, void *cmd)
141 {
142         struct dw_wdt *dw_wdt;
143         u32 val;
144 
145         dw_wdt = container_of(this, struct dw_wdt, restart_handler);
146 
147         writel(0, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
148         val = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
149         if (val & WDOG_CONTROL_REG_WDT_EN_MASK)
150                 writel(WDOG_COUNTER_RESTART_KICK_VALUE,
151                        dw_wdt->regs + WDOG_COUNTER_RESTART_REG_OFFSET);
152         else
153                 writel(WDOG_CONTROL_REG_WDT_EN_MASK,
154                        dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
155 
156         /* wait for reset to assert... */
157         mdelay(500);
158 
159         return NOTIFY_DONE;
160 }
161 
162 static unsigned int dw_wdt_get_timeleft(struct watchdog_device *wdd)
163 {
164         struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
165 
166         return readl(dw_wdt->regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
167                 dw_wdt->rate;
168 }
169 
170 static const struct watchdog_info dw_wdt_ident = {
171         .options        = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
172                           WDIOF_MAGICCLOSE,
173         .identity       = "Synopsys DesignWare Watchdog",
174 };
175 
176 static const struct watchdog_ops dw_wdt_ops = {
177         .owner          = THIS_MODULE,
178         .start          = dw_wdt_start,
179         .ping           = dw_wdt_ping,
180         .set_timeout    = dw_wdt_set_timeout,
181         .get_timeleft   = dw_wdt_get_timeleft,
182 };
183 
184 #ifdef CONFIG_PM_SLEEP
185 static int dw_wdt_suspend(struct device *dev)
186 {
187         struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
188 
189         clk_disable_unprepare(dw_wdt->clk);
190 
191         return 0;
192 }
193 
194 static int dw_wdt_resume(struct device *dev)
195 {
196         struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
197         int err = clk_prepare_enable(dw_wdt->clk);
198 
199         if (err)
200                 return err;
201 
202         dw_wdt_ping(&dw_wdt->wdd);
203 
204         return 0;
205 }
206 #endif /* CONFIG_PM_SLEEP */
207 
208 static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);
209 
210 static int dw_wdt_drv_probe(struct platform_device *pdev)
211 {
212         struct device *dev = &pdev->dev;
213         struct watchdog_device *wdd;
214         struct dw_wdt *dw_wdt;
215         struct resource *mem;
216         int ret;
217 
218         dw_wdt = devm_kzalloc(dev, sizeof(*dw_wdt), GFP_KERNEL);
219         if (!dw_wdt)
220                 return -ENOMEM;
221 
222         mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
223         dw_wdt->regs = devm_ioremap_resource(dev, mem);
224         if (IS_ERR(dw_wdt->regs))
225                 return PTR_ERR(dw_wdt->regs);
226 
227         dw_wdt->clk = devm_clk_get(dev, NULL);
228         if (IS_ERR(dw_wdt->clk))
229                 return PTR_ERR(dw_wdt->clk);
230 
231         ret = clk_prepare_enable(dw_wdt->clk);
232         if (ret)
233                 return ret;
234 
235         dw_wdt->rate = clk_get_rate(dw_wdt->clk);
236         if (dw_wdt->rate == 0) {
237                 ret = -EINVAL;
238                 goto out_disable_clk;
239         }
240 
241         wdd = &dw_wdt->wdd;
242         wdd->info = &dw_wdt_ident;
243         wdd->ops = &dw_wdt_ops;
244         wdd->min_timeout = 1;
245         wdd->max_hw_heartbeat_ms =
246                 dw_wdt_top_in_seconds(dw_wdt, DW_WDT_MAX_TOP) * 1000;
247         wdd->parent = dev;
248 
249         watchdog_set_drvdata(wdd, dw_wdt);
250         watchdog_set_nowayout(wdd, nowayout);
251         watchdog_init_timeout(wdd, 0, dev);
252 
253         /*
254          * If the watchdog is already running, use its already configured
255          * timeout. Otherwise use the default or the value provided through
256          * devicetree.
257          */
258         if (dw_wdt_is_enabled(dw_wdt)) {
259                 wdd->timeout = dw_wdt_get_top(dw_wdt);
260                 set_bit(WDOG_HW_RUNNING, &wdd->status);
261         } else {
262                 wdd->timeout = DW_WDT_DEFAULT_SECONDS;
263                 watchdog_init_timeout(wdd, 0, dev);
264         }
265 
266         platform_set_drvdata(pdev, dw_wdt);
267 
268         ret = watchdog_register_device(wdd);
269         if (ret)
270                 goto out_disable_clk;
271 
272         dw_wdt->restart_handler.notifier_call = dw_wdt_restart_handle;
273         dw_wdt->restart_handler.priority = 128;
274         ret = register_restart_handler(&dw_wdt->restart_handler);
275         if (ret)
276                 pr_warn("cannot register restart handler\n");
277 
278         return 0;
279 
280 out_disable_clk:
281         clk_disable_unprepare(dw_wdt->clk);
282         return ret;
283 }
284 
285 static int dw_wdt_drv_remove(struct platform_device *pdev)
286 {
287         struct dw_wdt *dw_wdt = platform_get_drvdata(pdev);
288 
289         unregister_restart_handler(&dw_wdt->restart_handler);
290         watchdog_unregister_device(&dw_wdt->wdd);
291         clk_disable_unprepare(dw_wdt->clk);
292 
293         return 0;
294 }
295 
296 #ifdef CONFIG_OF
297 static const struct of_device_id dw_wdt_of_match[] = {
298         { .compatible = "snps,dw-wdt", },
299         { /* sentinel */ }
300 };
301 MODULE_DEVICE_TABLE(of, dw_wdt_of_match);
302 #endif
303 
304 static struct platform_driver dw_wdt_driver = {
305         .probe          = dw_wdt_drv_probe,
306         .remove         = dw_wdt_drv_remove,
307         .driver         = {
308                 .name   = "dw_wdt",
309                 .of_match_table = of_match_ptr(dw_wdt_of_match),
310                 .pm     = &dw_wdt_pm_ops,
311         },
312 };
313 
314 module_platform_driver(dw_wdt_driver);
315 
316 MODULE_AUTHOR("Jamie Iles");
317 MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
318 MODULE_LICENSE("GPL");
319 

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