1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2013 Broadcom Corporation
4 *
5 */
6
7 #include <linux/debugfs.h>
8 #include <linux/delay.h>
9 #include <linux/err.h>
10 #include <linux/io.h>
11 #include <linux/module.h>
12 #include <linux/of_address.h>
13 #include <linux/platform_device.h>
14 #include <linux/watchdog.h>
15
16 #define SECWDOG_CTRL_REG 0x00000000
17 #define SECWDOG_COUNT_REG 0x00000004
18
19 #define SECWDOG_RESERVED_MASK 0x1dffffff
20 #define SECWDOG_WD_LOAD_FLAG 0x10000000
21 #define SECWDOG_EN_MASK 0x08000000
22 #define SECWDOG_SRSTEN_MASK 0x04000000
23 #define SECWDOG_RES_MASK 0x00f00000
24 #define SECWDOG_COUNT_MASK 0x000fffff
25
26 #define SECWDOG_MAX_COUNT SECWDOG_COUNT_MASK
27 #define SECWDOG_CLKS_SHIFT 20
28 #define SECWDOG_MAX_RES 15
29 #define SECWDOG_DEFAULT_RESOLUTION 4
30 #define SECWDOG_MAX_TRY 1000
31
32 #define SECS_TO_TICKS(x, w) ((x) << (w)->resolution)
33 #define TICKS_TO_SECS(x, w) ((x) >> (w)->resolution)
34
35 #define BCM_KONA_WDT_NAME "bcm_kona_wdt"
36
37 struct bcm_kona_wdt {
38 void __iomem *base;
39 /*
40 * One watchdog tick is 1/(2^resolution) seconds. Resolution can take
41 * the values 0-15, meaning one tick can be 1s to 30.52us. Our default
42 * resolution of 4 means one tick is 62.5ms.
43 *
44 * The watchdog counter is 20 bits. Depending on resolution, the maximum
45 * counter value of 0xfffff expires after about 12 days (resolution 0)
46 * down to only 32s (resolution 15). The default resolution of 4 gives
47 * us a maximum of about 18 hours and 12 minutes before the watchdog
48 * times out.
49 */
50 int resolution;
51 spinlock_t lock;
52 #ifdef CONFIG_BCM_KONA_WDT_DEBUG
53 unsigned long busy_count;
54 struct dentry *debugfs;
55 #endif
56 };
57
secure_register_read(struct bcm_kona_wdt * wdt,uint32_t offset)58 static int secure_register_read(struct bcm_kona_wdt *wdt, uint32_t offset)
59 {
60 uint32_t val;
61 unsigned count = 0;
62
63 /*
64 * If the WD_LOAD_FLAG is set, the watchdog counter field is being
65 * updated in hardware. Once the WD timer is updated in hardware, it
66 * gets cleared.
67 */
68 do {
69 if (unlikely(count > 1))
70 udelay(5);
71 val = readl_relaxed(wdt->base + offset);
72 count++;
73 } while ((val & SECWDOG_WD_LOAD_FLAG) && count < SECWDOG_MAX_TRY);
74
75 #ifdef CONFIG_BCM_KONA_WDT_DEBUG
76 /* Remember the maximum number iterations due to WD_LOAD_FLAG */
77 if (count > wdt->busy_count)
78 wdt->busy_count = count;
79 #endif
80
81 /* This is the only place we return a negative value. */
82 if (val & SECWDOG_WD_LOAD_FLAG)
83 return -ETIMEDOUT;
84
85 /* We always mask out reserved bits. */
86 val &= SECWDOG_RESERVED_MASK;
87
88 return val;
89 }
90
91 #ifdef CONFIG_BCM_KONA_WDT_DEBUG
92
bcm_kona_show(struct seq_file * s,void * data)93 static int bcm_kona_show(struct seq_file *s, void *data)
94 {
95 int ctl_val, cur_val;
96 unsigned long flags;
97 struct bcm_kona_wdt *wdt = s->private;
98
99 if (!wdt) {
100 seq_puts(s, "No device pointer\n");
101 return 0;
102 }
103
104 spin_lock_irqsave(&wdt->lock, flags);
105 ctl_val = secure_register_read(wdt, SECWDOG_CTRL_REG);
106 cur_val = secure_register_read(wdt, SECWDOG_COUNT_REG);
107 spin_unlock_irqrestore(&wdt->lock, flags);
108
109 if (ctl_val < 0 || cur_val < 0) {
110 seq_puts(s, "Error accessing hardware\n");
111 } else {
112 int ctl, cur, ctl_sec, cur_sec, res;
113
114 ctl = ctl_val & SECWDOG_COUNT_MASK;
115 res = (ctl_val & SECWDOG_RES_MASK) >> SECWDOG_CLKS_SHIFT;
116 cur = cur_val & SECWDOG_COUNT_MASK;
117 ctl_sec = TICKS_TO_SECS(ctl, wdt);
118 cur_sec = TICKS_TO_SECS(cur, wdt);
119 seq_printf(s,
120 "Resolution: %d / %d\n"
121 "Control: %d s / %d (%#x) ticks\n"
122 "Current: %d s / %d (%#x) ticks\n"
123 "Busy count: %lu\n",
124 res, wdt->resolution,
125 ctl_sec, ctl, ctl,
126 cur_sec, cur, cur,
127 wdt->busy_count);
128 }
129
130 return 0;
131 }
132
133 DEFINE_SHOW_ATTRIBUTE(bcm_kona);
134
bcm_kona_wdt_debug_init(struct platform_device * pdev)135 static void bcm_kona_wdt_debug_init(struct platform_device *pdev)
136 {
137 struct dentry *dir;
138 struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
139
140 if (!wdt)
141 return;
142
143 wdt->debugfs = NULL;
144
145 dir = debugfs_create_dir(BCM_KONA_WDT_NAME, NULL);
146
147 debugfs_create_file("info", S_IFREG | S_IRUGO, dir, wdt,
148 &bcm_kona_fops);
149 wdt->debugfs = dir;
150 }
151
bcm_kona_wdt_debug_exit(struct platform_device * pdev)152 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev)
153 {
154 struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
155
156 if (wdt)
157 debugfs_remove_recursive(wdt->debugfs);
158 }
159
160 #else
161
bcm_kona_wdt_debug_init(struct platform_device * pdev)162 static void bcm_kona_wdt_debug_init(struct platform_device *pdev) {}
bcm_kona_wdt_debug_exit(struct platform_device * pdev)163 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) {}
164
165 #endif /* CONFIG_BCM_KONA_WDT_DEBUG */
166
bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt * wdt,unsigned mask,unsigned newval)167 static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt,
168 unsigned mask, unsigned newval)
169 {
170 int val;
171 unsigned long flags;
172 int ret = 0;
173
174 spin_lock_irqsave(&wdt->lock, flags);
175
176 val = secure_register_read(wdt, SECWDOG_CTRL_REG);
177 if (val < 0) {
178 ret = val;
179 } else {
180 val &= ~mask;
181 val |= newval;
182 writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG);
183 }
184
185 spin_unlock_irqrestore(&wdt->lock, flags);
186
187 return ret;
188 }
189
bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt * wdt)190 static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt)
191 {
192 if (wdt->resolution > SECWDOG_MAX_RES)
193 return -EINVAL;
194
195 return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK,
196 wdt->resolution << SECWDOG_CLKS_SHIFT);
197 }
198
bcm_kona_wdt_set_timeout_reg(struct watchdog_device * wdog,unsigned watchdog_flags)199 static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog,
200 unsigned watchdog_flags)
201 {
202 struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
203
204 return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK,
205 SECS_TO_TICKS(wdog->timeout, wdt) |
206 watchdog_flags);
207 }
208
bcm_kona_wdt_set_timeout(struct watchdog_device * wdog,unsigned int t)209 static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog,
210 unsigned int t)
211 {
212 wdog->timeout = t;
213 return 0;
214 }
215
bcm_kona_wdt_get_timeleft(struct watchdog_device * wdog)216 static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog)
217 {
218 struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
219 int val;
220 unsigned long flags;
221
222 spin_lock_irqsave(&wdt->lock, flags);
223 val = secure_register_read(wdt, SECWDOG_COUNT_REG);
224 spin_unlock_irqrestore(&wdt->lock, flags);
225
226 if (val < 0)
227 return val;
228
229 return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt);
230 }
231
bcm_kona_wdt_start(struct watchdog_device * wdog)232 static int bcm_kona_wdt_start(struct watchdog_device *wdog)
233 {
234 return bcm_kona_wdt_set_timeout_reg(wdog,
235 SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK);
236 }
237
bcm_kona_wdt_stop(struct watchdog_device * wdog)238 static int bcm_kona_wdt_stop(struct watchdog_device *wdog)
239 {
240 struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog);
241
242 return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK |
243 SECWDOG_SRSTEN_MASK, 0);
244 }
245
246 static const struct watchdog_ops bcm_kona_wdt_ops = {
247 .owner = THIS_MODULE,
248 .start = bcm_kona_wdt_start,
249 .stop = bcm_kona_wdt_stop,
250 .set_timeout = bcm_kona_wdt_set_timeout,
251 .get_timeleft = bcm_kona_wdt_get_timeleft,
252 };
253
254 static const struct watchdog_info bcm_kona_wdt_info = {
255 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
256 WDIOF_KEEPALIVEPING,
257 .identity = "Broadcom Kona Watchdog Timer",
258 };
259
260 static struct watchdog_device bcm_kona_wdt_wdd = {
261 .info = &bcm_kona_wdt_info,
262 .ops = &bcm_kona_wdt_ops,
263 .min_timeout = 1,
264 .max_timeout = SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
265 .timeout = SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION,
266 };
267
bcm_kona_wdt_probe(struct platform_device * pdev)268 static int bcm_kona_wdt_probe(struct platform_device *pdev)
269 {
270 struct device *dev = &pdev->dev;
271 struct bcm_kona_wdt *wdt;
272 int ret;
273
274 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
275 if (!wdt)
276 return -ENOMEM;
277
278 spin_lock_init(&wdt->lock);
279
280 wdt->base = devm_platform_ioremap_resource(pdev, 0);
281 if (IS_ERR(wdt->base))
282 return PTR_ERR(wdt->base);
283
284 wdt->resolution = SECWDOG_DEFAULT_RESOLUTION;
285 ret = bcm_kona_wdt_set_resolution_reg(wdt);
286 if (ret) {
287 dev_err(dev, "Failed to set resolution (error: %d)", ret);
288 return ret;
289 }
290
291 platform_set_drvdata(pdev, wdt);
292 watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt);
293 bcm_kona_wdt_wdd.parent = dev;
294
295 ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0);
296 if (ret) {
297 dev_err(dev, "Failed set watchdog timeout");
298 return ret;
299 }
300
301 watchdog_stop_on_reboot(&bcm_kona_wdt_wdd);
302 watchdog_stop_on_unregister(&bcm_kona_wdt_wdd);
303 ret = devm_watchdog_register_device(dev, &bcm_kona_wdt_wdd);
304 if (ret)
305 return ret;
306
307 bcm_kona_wdt_debug_init(pdev);
308 dev_dbg(dev, "Broadcom Kona Watchdog Timer");
309
310 return 0;
311 }
312
bcm_kona_wdt_remove(struct platform_device * pdev)313 static void bcm_kona_wdt_remove(struct platform_device *pdev)
314 {
315 bcm_kona_wdt_debug_exit(pdev);
316 dev_dbg(&pdev->dev, "Watchdog driver disabled");
317 }
318
319 static const struct of_device_id bcm_kona_wdt_of_match[] = {
320 { .compatible = "brcm,kona-wdt", },
321 {},
322 };
323 MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match);
324
325 static struct platform_driver bcm_kona_wdt_driver = {
326 .driver = {
327 .name = BCM_KONA_WDT_NAME,
328 .of_match_table = bcm_kona_wdt_of_match,
329 },
330 .probe = bcm_kona_wdt_probe,
331 .remove = bcm_kona_wdt_remove,
332 };
333
334 module_platform_driver(bcm_kona_wdt_driver);
335
336 MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME);
337 MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>");
338 MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver");
339 MODULE_LICENSE("GPL v2");
340