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6adb730d MM |
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 | ||
6e2ac20e | 14 | #include <linux/debugfs.h> |
6adb730d MM |
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; | |
6e2ac20e MM |
59 | #ifdef CONFIG_BCM_KONA_WDT_DEBUG |
60 | unsigned long busy_count; | |
61 | struct dentry *debugfs; | |
62 | #endif | |
6adb730d MM |
63 | }; |
64 | ||
6e2ac20e | 65 | static int secure_register_read(struct bcm_kona_wdt *wdt, uint32_t offset) |
6adb730d MM |
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); | |
6e2ac20e | 78 | val = readl_relaxed(wdt->base + offset); |
6adb730d MM |
79 | count++; |
80 | } while ((val & SECWDOG_WD_LOAD_FLAG) && count < SECWDOG_MAX_TRY); | |
81 | ||
6e2ac20e MM |
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 | ||
6adb730d MM |
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 | ||
6e2ac20e MM |
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, ret; | |
103 | unsigned long flags; | |
104 | struct bcm_kona_wdt *wdt = s->private; | |
105 | ||
106 | if (!wdt) | |
107 | return seq_puts(s, "No device pointer\n"); | |
108 | ||
109 | spin_lock_irqsave(&wdt->lock, flags); | |
110 | ctl_val = secure_register_read(wdt, SECWDOG_CTRL_REG); | |
111 | cur_val = secure_register_read(wdt, SECWDOG_COUNT_REG); | |
112 | spin_unlock_irqrestore(&wdt->lock, flags); | |
113 | ||
114 | if (ctl_val < 0 || cur_val < 0) { | |
115 | ret = seq_puts(s, "Error accessing hardware\n"); | |
116 | } else { | |
117 | int ctl, cur, ctl_sec, cur_sec, res; | |
118 | ||
119 | ctl = ctl_val & SECWDOG_COUNT_MASK; | |
120 | res = (ctl_val & SECWDOG_RES_MASK) >> SECWDOG_CLKS_SHIFT; | |
121 | cur = cur_val & SECWDOG_COUNT_MASK; | |
122 | ctl_sec = TICKS_TO_SECS(ctl, wdt); | |
123 | cur_sec = TICKS_TO_SECS(cur, wdt); | |
124 | ret = seq_printf(s, "Resolution: %d / %d\n" | |
125 | "Control: %d s / %d (%#x) ticks\n" | |
126 | "Current: %d s / %d (%#x) ticks\n" | |
127 | "Busy count: %lu\n", res, | |
128 | wdt->resolution, ctl_sec, ctl, ctl, cur_sec, | |
129 | cur, cur, wdt->busy_count); | |
130 | } | |
131 | ||
132 | return ret; | |
133 | } | |
134 | ||
135 | static int bcm_kona_dbg_open(struct inode *inode, struct file *file) | |
136 | { | |
137 | return single_open(file, bcm_kona_wdt_dbg_show, inode->i_private); | |
138 | } | |
139 | ||
140 | static const struct file_operations bcm_kona_dbg_operations = { | |
141 | .open = bcm_kona_dbg_open, | |
142 | .read = seq_read, | |
143 | .llseek = seq_lseek, | |
144 | .release = single_release, | |
145 | }; | |
146 | ||
147 | static void bcm_kona_wdt_debug_init(struct platform_device *pdev) | |
148 | { | |
149 | struct dentry *dir; | |
150 | struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev); | |
151 | ||
152 | if (!wdt) | |
153 | return; | |
154 | ||
155 | wdt->debugfs = NULL; | |
156 | ||
157 | dir = debugfs_create_dir(BCM_KONA_WDT_NAME, NULL); | |
158 | if (IS_ERR_OR_NULL(dir)) | |
159 | return; | |
160 | ||
161 | if (debugfs_create_file("info", S_IFREG | S_IRUGO, dir, wdt, | |
162 | &bcm_kona_dbg_operations)) | |
163 | wdt->debugfs = dir; | |
164 | else | |
165 | debugfs_remove_recursive(dir); | |
166 | } | |
167 | ||
168 | static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) | |
169 | { | |
170 | struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev); | |
171 | ||
172 | if (wdt && wdt->debugfs) { | |
173 | debugfs_remove_recursive(wdt->debugfs); | |
174 | wdt->debugfs = NULL; | |
175 | } | |
176 | } | |
177 | ||
178 | #else | |
179 | ||
180 | static void bcm_kona_wdt_debug_init(struct platform_device *pdev) {} | |
181 | static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) {} | |
182 | ||
183 | #endif /* CONFIG_BCM_KONA_WDT_DEBUG */ | |
184 | ||
6adb730d MM |
185 | static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt, |
186 | unsigned mask, unsigned newval) | |
187 | { | |
188 | int val; | |
189 | unsigned long flags; | |
190 | int ret = 0; | |
191 | ||
192 | spin_lock_irqsave(&wdt->lock, flags); | |
193 | ||
6e2ac20e | 194 | val = secure_register_read(wdt, SECWDOG_CTRL_REG); |
6adb730d MM |
195 | if (val < 0) { |
196 | ret = val; | |
197 | } else { | |
198 | val &= ~mask; | |
199 | val |= newval; | |
200 | writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG); | |
201 | } | |
202 | ||
203 | spin_unlock_irqrestore(&wdt->lock, flags); | |
204 | ||
205 | return ret; | |
206 | } | |
207 | ||
208 | static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt) | |
209 | { | |
210 | if (wdt->resolution > SECWDOG_MAX_RES) | |
211 | return -EINVAL; | |
212 | ||
213 | return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK, | |
214 | wdt->resolution << SECWDOG_CLKS_SHIFT); | |
215 | } | |
216 | ||
217 | static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog, | |
218 | unsigned watchdog_flags) | |
219 | { | |
220 | struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); | |
221 | ||
222 | return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK, | |
223 | SECS_TO_TICKS(wdog->timeout, wdt) | | |
224 | watchdog_flags); | |
225 | } | |
226 | ||
227 | static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog, | |
228 | unsigned int t) | |
229 | { | |
230 | wdog->timeout = t; | |
231 | return 0; | |
232 | } | |
233 | ||
234 | static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog) | |
235 | { | |
236 | struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); | |
237 | int val; | |
238 | unsigned long flags; | |
239 | ||
240 | spin_lock_irqsave(&wdt->lock, flags); | |
6e2ac20e | 241 | val = secure_register_read(wdt, SECWDOG_COUNT_REG); |
6adb730d MM |
242 | spin_unlock_irqrestore(&wdt->lock, flags); |
243 | ||
244 | if (val < 0) | |
245 | return val; | |
246 | ||
247 | return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt); | |
248 | } | |
249 | ||
250 | static int bcm_kona_wdt_start(struct watchdog_device *wdog) | |
251 | { | |
252 | return bcm_kona_wdt_set_timeout_reg(wdog, | |
253 | SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK); | |
254 | } | |
255 | ||
256 | static int bcm_kona_wdt_stop(struct watchdog_device *wdog) | |
257 | { | |
258 | struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); | |
259 | ||
260 | return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK | | |
261 | SECWDOG_SRSTEN_MASK, 0); | |
262 | } | |
263 | ||
264 | static struct watchdog_ops bcm_kona_wdt_ops = { | |
265 | .owner = THIS_MODULE, | |
266 | .start = bcm_kona_wdt_start, | |
267 | .stop = bcm_kona_wdt_stop, | |
268 | .set_timeout = bcm_kona_wdt_set_timeout, | |
269 | .get_timeleft = bcm_kona_wdt_get_timeleft, | |
270 | }; | |
271 | ||
272 | static struct watchdog_info bcm_kona_wdt_info = { | |
273 | .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | | |
274 | WDIOF_KEEPALIVEPING, | |
275 | .identity = "Broadcom Kona Watchdog Timer", | |
276 | }; | |
277 | ||
278 | static struct watchdog_device bcm_kona_wdt_wdd = { | |
279 | .info = &bcm_kona_wdt_info, | |
280 | .ops = &bcm_kona_wdt_ops, | |
281 | .min_timeout = 1, | |
282 | .max_timeout = SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION, | |
283 | .timeout = SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION, | |
284 | }; | |
285 | ||
286 | static void bcm_kona_wdt_shutdown(struct platform_device *pdev) | |
287 | { | |
288 | bcm_kona_wdt_stop(&bcm_kona_wdt_wdd); | |
289 | } | |
290 | ||
291 | static int bcm_kona_wdt_probe(struct platform_device *pdev) | |
292 | { | |
293 | struct device *dev = &pdev->dev; | |
294 | struct bcm_kona_wdt *wdt; | |
295 | struct resource *res; | |
296 | int ret; | |
297 | ||
298 | wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); | |
299 | if (!wdt) | |
300 | return -ENOMEM; | |
301 | ||
302 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
303 | wdt->base = devm_ioremap_resource(dev, res); | |
304 | if (IS_ERR(wdt->base)) | |
305 | return -ENODEV; | |
306 | ||
307 | wdt->resolution = SECWDOG_DEFAULT_RESOLUTION; | |
308 | ret = bcm_kona_wdt_set_resolution_reg(wdt); | |
309 | if (ret) { | |
310 | dev_err(dev, "Failed to set resolution (error: %d)", ret); | |
311 | return ret; | |
312 | } | |
313 | ||
314 | spin_lock_init(&wdt->lock); | |
315 | platform_set_drvdata(pdev, wdt); | |
316 | watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt); | |
317 | ||
318 | ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0); | |
319 | if (ret) { | |
320 | dev_err(dev, "Failed set watchdog timeout"); | |
321 | return ret; | |
322 | } | |
323 | ||
324 | ret = watchdog_register_device(&bcm_kona_wdt_wdd); | |
325 | if (ret) { | |
326 | dev_err(dev, "Failed to register watchdog device"); | |
327 | return ret; | |
328 | } | |
329 | ||
6e2ac20e | 330 | bcm_kona_wdt_debug_init(pdev); |
6adb730d MM |
331 | dev_dbg(dev, "Broadcom Kona Watchdog Timer"); |
332 | ||
333 | return 0; | |
334 | } | |
335 | ||
336 | static int bcm_kona_wdt_remove(struct platform_device *pdev) | |
337 | { | |
6e2ac20e | 338 | bcm_kona_wdt_debug_exit(pdev); |
6adb730d MM |
339 | bcm_kona_wdt_shutdown(pdev); |
340 | watchdog_unregister_device(&bcm_kona_wdt_wdd); | |
341 | dev_dbg(&pdev->dev, "Watchdog driver disabled"); | |
342 | ||
343 | return 0; | |
344 | } | |
345 | ||
346 | static const struct of_device_id bcm_kona_wdt_of_match[] = { | |
347 | { .compatible = "brcm,kona-wdt", }, | |
348 | {}, | |
349 | }; | |
350 | MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match); | |
351 | ||
352 | static struct platform_driver bcm_kona_wdt_driver = { | |
353 | .driver = { | |
354 | .name = BCM_KONA_WDT_NAME, | |
355 | .owner = THIS_MODULE, | |
356 | .of_match_table = bcm_kona_wdt_of_match, | |
357 | }, | |
358 | .probe = bcm_kona_wdt_probe, | |
359 | .remove = bcm_kona_wdt_remove, | |
360 | .shutdown = bcm_kona_wdt_shutdown, | |
361 | }; | |
362 | ||
363 | module_platform_driver(bcm_kona_wdt_driver); | |
364 | ||
365 | MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME); | |
366 | MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>"); | |
367 | MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver"); | |
368 | MODULE_LICENSE("GPL v2"); |