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Linux/drivers/watchdog/bcm_kona_wdt.c

  1 /*
  2  * Copyright (C) 2013 Broadcom Corporation
  3  *
  4  * This program is free software; you can redistribute it and/or
  5  * modify it under the terms of the GNU General Public License as
  6  * published by the Free Software Foundation version 2.
  7  *
  8  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
  9  * kind, whether express or implied; without even the implied warranty
 10  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 11  * GNU General Public License for more details.
 12  */
 13 
 14 #include <linux/debugfs.h>
 15 #include <linux/delay.h>
 16 #include <linux/err.h>
 17 #include <linux/io.h>
 18 #include <linux/module.h>
 19 #include <linux/of_address.h>
 20 #include <linux/platform_device.h>
 21 #include <linux/watchdog.h>
 22 
 23 #define SECWDOG_CTRL_REG                0x00000000
 24 #define SECWDOG_COUNT_REG               0x00000004
 25 
 26 #define SECWDOG_RESERVED_MASK           0x1dffffff
 27 #define SECWDOG_WD_LOAD_FLAG            0x10000000
 28 #define SECWDOG_EN_MASK                 0x08000000
 29 #define SECWDOG_SRSTEN_MASK             0x04000000
 30 #define SECWDOG_RES_MASK                0x00f00000
 31 #define SECWDOG_COUNT_MASK              0x000fffff
 32 
 33 #define SECWDOG_MAX_COUNT               SECWDOG_COUNT_MASK
 34 #define SECWDOG_CLKS_SHIFT              20
 35 #define SECWDOG_MAX_RES                 15
 36 #define SECWDOG_DEFAULT_RESOLUTION      4
 37 #define SECWDOG_MAX_TRY                 1000
 38 
 39 #define SECS_TO_TICKS(x, w)             ((x) << (w)->resolution)
 40 #define TICKS_TO_SECS(x, w)             ((x) >> (w)->resolution)
 41 
 42 #define BCM_KONA_WDT_NAME               "bcm_kona_wdt"
 43 
 44 struct bcm_kona_wdt {
 45         void __iomem *base;
 46         /*
 47          * One watchdog tick is 1/(2^resolution) seconds. Resolution can take
 48          * the values 0-15, meaning one tick can be 1s to 30.52us. Our default
 49          * resolution of 4 means one tick is 62.5ms.
 50          *
 51          * The watchdog counter is 20 bits. Depending on resolution, the maximum
 52          * counter value of 0xfffff expires after about 12 days (resolution 0)
 53          * down to only 32s (resolution 15). The default resolution of 4 gives
 54          * us a maximum of about 18 hours and 12 minutes before the watchdog
 55          * times out.
 56          */
 57         int resolution;
 58         spinlock_t lock;
 59 #ifdef CONFIG_BCM_KONA_WDT_DEBUG
 60         unsigned long busy_count;
 61         struct dentry *debugfs;
 62 #endif
 63 };
 64 
 65 static int secure_register_read(struct bcm_kona_wdt *wdt, uint32_t offset)
 66 {
 67         uint32_t val;
 68         unsigned count = 0;
 69 
 70         /*
 71          * If the WD_LOAD_FLAG is set, the watchdog counter field is being
 72          * updated in hardware. Once the WD timer is updated in hardware, it
 73          * gets cleared.
 74          */
 75         do {
 76                 if (unlikely(count > 1))
 77                         udelay(5);
 78                 val = readl_relaxed(wdt->base + offset);
 79                 count++;
 80         } while ((val & SECWDOG_WD_LOAD_FLAG) && count < SECWDOG_MAX_TRY);
 81 
 82 #ifdef CONFIG_BCM_KONA_WDT_DEBUG
 83         /* Remember the maximum number iterations due to WD_LOAD_FLAG */
 84         if (count > wdt->busy_count)
 85                 wdt->busy_count = count;
 86 #endif
 87 
 88         /* This is the only place we return a negative value. */
 89         if (val & SECWDOG_WD_LOAD_FLAG)
 90                 return -ETIMEDOUT;
 91 
 92         /* We always mask out reserved bits. */
 93         val &= SECWDOG_RESERVED_MASK;
 94 
 95         return val;
 96 }
 97 
 98 #ifdef CONFIG_BCM_KONA_WDT_DEBUG
 99 
100 static int bcm_kona_wdt_dbg_show(struct seq_file *s, void *data)
101 {
102         int ctl_val, cur_val;
103         unsigned long flags;
104         struct bcm_kona_wdt *wdt = s->private;
105 
106         if (!wdt) {
107                 seq_puts(s, "No device pointer\n");
108                 return 0;
109         }
110 
111         spin_lock_irqsave(&wdt->lock, flags);
112         ctl_val = secure_register_read(wdt, SECWDOG_CTRL_REG);
113         cur_val = secure_register_read(wdt, SECWDOG_COUNT_REG);
114         spin_unlock_irqrestore(&wdt->lock, flags);
115 
116         if (ctl_val < 0 || cur_val < 0) {
117                 seq_puts(s, "Error accessing hardware\n");
118         } else {
119                 int ctl, cur, ctl_sec, cur_sec, res;
120 
121                 ctl = ctl_val & SECWDOG_COUNT_MASK;
122                 res = (ctl_val & SECWDOG_RES_MASK) >> SECWDOG_CLKS_SHIFT;
123                 cur = cur_val & SECWDOG_COUNT_MASK;
124                 ctl_sec = TICKS_TO_SECS(ctl, wdt);
125                 cur_sec = TICKS_TO_SECS(cur, wdt);
126                 seq_printf(s,
127                            "Resolution: %d / %d\n"
128                            "Control: %d s / %d (%#x) ticks\n"
129                            "Current: %d s / %d (%#x) ticks\n"
130                            "Busy count: %lu\n",
131                            res, wdt->resolution,
132                            ctl_sec, ctl, ctl,
133                            cur_sec, cur, cur,
134                            wdt->busy_count);
135         }
136 
137         return 0;
138 }
139 
140 static int bcm_kona_dbg_open(struct inode *inode, struct file *file)
141 {
142         return single_open(file, bcm_kona_wdt_dbg_show, inode->i_private);
143 }
144 
145 static const struct file_operations bcm_kona_dbg_operations = {
146         .open           = bcm_kona_dbg_open,
147         .read           = seq_read,
148         .llseek         = seq_lseek,
149         .release        = single_release,
150 };
151 
152 static void bcm_kona_wdt_debug_init(struct platform_device *pdev)
153 {
154         struct dentry *dir;
155         struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
156 
157         if (!wdt)
158                 return;
159 
160         wdt->debugfs = NULL;
161 
162         dir = debugfs_create_dir(BCM_KONA_WDT_NAME, NULL);
163         if (IS_ERR_OR_NULL(dir))
164                 return;
165 
166         if (debugfs_create_file("info", S_IFREG | S_IRUGO, dir, wdt,
167                                 &bcm_kona_dbg_operations))
168                 wdt->debugfs = dir;
169         else
170                 debugfs_remove_recursive(dir);
171 }
172 
173 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev)
174 {
175         struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
176 
177         if (wdt && wdt->debugfs) {
178                 debugfs_remove_recursive(wdt->debugfs);
179                 wdt->debugfs = NULL;
180         }
181 }
182 
183 #else
184 
185 static void bcm_kona_wdt_debug_init(struct platform_device *pdev) {}
186 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) {}
187 
188 #endif /* CONFIG_BCM_KONA_WDT_DEBUG */
189 
190 static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt,
191                                         unsigned mask, unsigned newval)
192 {
193         int val;
194         unsigned long flags;
195         int ret = 0;
196 
197         spin_lock_irqsave(&wdt->lock, flags);
198 
199         val = secure_register_read(wdt, SECWDOG_CTRL_REG);
200         if (val < 0) {
201                 ret = val;
202         } else {
203                 val &= ~mask;
204                 val |= newval;
205                 writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG);
206         }
207 
208         spin_unlock_irqrestore(&wdt->lock, flags);
209 
210         return ret;
211 }
212 
213 static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt)
214 {
215         if (wdt->resolution > SECWDOG_MAX_RES)
216                 return -EINVAL;
217 
218         return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK,
219                                         wdt->resolution << SECWDOG_CLKS_SHIFT);
220 }
221 
222 static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog,
223                                         unsigned watchdog_flags)
224 {
225         struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
226 
227         return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK,
228                                         SECS_TO_TICKS(wdog->timeout, wdt) |
229                                         watchdog_flags);
230 }
231 
232 static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog,
233         unsigned int t)
234 {
235         wdog->timeout = t;
236         return 0;
237 }
238 
239 static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog)
240 {
241         struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
242         int val;
243         unsigned long flags;
244 
245         spin_lock_irqsave(&wdt->lock, flags);
246         val = secure_register_read(wdt, SECWDOG_COUNT_REG);
247         spin_unlock_irqrestore(&wdt->lock, flags);
248 
249         if (val < 0)
250                 return val;
251 
252         return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt);
253 }
254 
255 static int bcm_kona_wdt_start(struct watchdog_device *wdog)
256 {
257         return bcm_kona_wdt_set_timeout_reg(wdog,
258                                         SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK);
259 }
260 
261 static int bcm_kona_wdt_stop(struct watchdog_device *wdog)
262 {
263         struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
264 
265         return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK |
266                                             SECWDOG_SRSTEN_MASK, 0);
267 }
268 
269 static struct watchdog_ops bcm_kona_wdt_ops = {
270         .owner =        THIS_MODULE,
271         .start =        bcm_kona_wdt_start,
272         .stop =         bcm_kona_wdt_stop,
273         .set_timeout =  bcm_kona_wdt_set_timeout,
274         .get_timeleft = bcm_kona_wdt_get_timeleft,
275 };
276 
277 static struct watchdog_info bcm_kona_wdt_info = {
278         .options =      WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
279                         WDIOF_KEEPALIVEPING,
280         .identity =     "Broadcom Kona Watchdog Timer",
281 };
282 
283 static struct watchdog_device bcm_kona_wdt_wdd = {
284         .info =         &bcm_kona_wdt_info,
285         .ops =          &bcm_kona_wdt_ops,
286         .min_timeout =  1,
287         .max_timeout =  SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
288         .timeout =      SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
289 };
290 
291 static void bcm_kona_wdt_shutdown(struct platform_device *pdev)
292 {
293         bcm_kona_wdt_stop(&bcm_kona_wdt_wdd);
294 }
295 
296 static int bcm_kona_wdt_probe(struct platform_device *pdev)
297 {
298         struct device *dev = &pdev->dev;
299         struct bcm_kona_wdt *wdt;
300         struct resource *res;
301         int ret;
302 
303         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
304         if (!wdt)
305                 return -ENOMEM;
306 
307         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
308         wdt->base = devm_ioremap_resource(dev, res);
309         if (IS_ERR(wdt->base))
310                 return -ENODEV;
311 
312         wdt->resolution = SECWDOG_DEFAULT_RESOLUTION;
313         ret = bcm_kona_wdt_set_resolution_reg(wdt);
314         if (ret) {
315                 dev_err(dev, "Failed to set resolution (error: %d)", ret);
316                 return ret;
317         }
318 
319         spin_lock_init(&wdt->lock);
320         platform_set_drvdata(pdev, wdt);
321         watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt);
322 
323         ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0);
324         if (ret) {
325                 dev_err(dev, "Failed set watchdog timeout");
326                 return ret;
327         }
328 
329         ret = watchdog_register_device(&bcm_kona_wdt_wdd);
330         if (ret) {
331                 dev_err(dev, "Failed to register watchdog device");
332                 return ret;
333         }
334 
335         bcm_kona_wdt_debug_init(pdev);
336         dev_dbg(dev, "Broadcom Kona Watchdog Timer");
337 
338         return 0;
339 }
340 
341 static int bcm_kona_wdt_remove(struct platform_device *pdev)
342 {
343         bcm_kona_wdt_debug_exit(pdev);
344         bcm_kona_wdt_shutdown(pdev);
345         watchdog_unregister_device(&bcm_kona_wdt_wdd);
346         dev_dbg(&pdev->dev, "Watchdog driver disabled");
347 
348         return 0;
349 }
350 
351 static const struct of_device_id bcm_kona_wdt_of_match[] = {
352         { .compatible = "brcm,kona-wdt", },
353         {},
354 };
355 MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match);
356 
357 static struct platform_driver bcm_kona_wdt_driver = {
358         .driver = {
359                         .name = BCM_KONA_WDT_NAME,
360                         .of_match_table = bcm_kona_wdt_of_match,
361                   },
362         .probe = bcm_kona_wdt_probe,
363         .remove = bcm_kona_wdt_remove,
364         .shutdown = bcm_kona_wdt_shutdown,
365 };
366 
367 module_platform_driver(bcm_kona_wdt_driver);
368 
369 MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME);
370 MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>");
371 MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver");
372 MODULE_LICENSE("GPL v2");
373 

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