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1/*
2 * Watchdog driver for Alphascale ASM9260.
3 *
4 * Copyright (c) 2014 Oleksij Rempel <linux@rempel-privat.de>
5 *
6 * Licensed under GPLv2 or later.
7 */
8
9#include <linux/bitops.h>
10#include <linux/clk.h>
11#include <linux/delay.h>
12#include <linux/interrupt.h>
13#include <linux/io.h>
14#include <linux/module.h>
15#include <linux/of.h>
16#include <linux/platform_device.h>
17#include <linux/reboot.h>
18#include <linux/reset.h>
19#include <linux/watchdog.h>
20
21#define CLOCK_FREQ 1000000
22
23/* Watchdog Mode register */
24#define HW_WDMOD 0x00
25/* Wake interrupt. Set by HW, can't be cleared. */
26#define BM_MOD_WDINT BIT(3)
27/* This bit set if timeout reached. Cleared by SW. */
28#define BM_MOD_WDTOF BIT(2)
29/* HW Reset on timeout */
30#define BM_MOD_WDRESET BIT(1)
31/* WD enable */
32#define BM_MOD_WDEN BIT(0)
33
34/*
35 * Watchdog Timer Constant register
36 * Minimal value is 0xff, the meaning of this value
37 * depends on used clock: T = WDCLK * (0xff + 1) * 4
38 */
39#define HW_WDTC 0x04
40#define BM_WDTC_MAX(freq) (0x7fffffff / (freq))
41
42/* Watchdog Feed register */
43#define HW_WDFEED 0x08
44
45/* Watchdog Timer Value register */
46#define HW_WDTV 0x0c
47
48#define ASM9260_WDT_DEFAULT_TIMEOUT 30
49
50enum asm9260_wdt_mode {
51 HW_RESET,
52 SW_RESET,
53 DEBUG,
54};
55
56struct asm9260_wdt_priv {
57 struct device *dev;
58 struct watchdog_device wdd;
59 struct clk *clk;
60 struct clk *clk_ahb;
61 struct reset_control *rst;
62 struct notifier_block restart_handler;
63
64 void __iomem *iobase;
65 int irq;
66 unsigned long wdt_freq;
67 enum asm9260_wdt_mode mode;
68};
69
70static int asm9260_wdt_feed(struct watchdog_device *wdd)
71{
72 struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
73
74 iowrite32(0xaa, priv->iobase + HW_WDFEED);
75 iowrite32(0x55, priv->iobase + HW_WDFEED);
76
77 return 0;
78}
79
80static unsigned int asm9260_wdt_gettimeleft(struct watchdog_device *wdd)
81{
82 struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
83 u32 counter;
84
85 counter = ioread32(priv->iobase + HW_WDTV);
86
87 return DIV_ROUND_CLOSEST(counter, priv->wdt_freq);
88}
89
90static int asm9260_wdt_updatetimeout(struct watchdog_device *wdd)
91{
92 struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
93 u32 counter;
94
95 counter = wdd->timeout * priv->wdt_freq;
96
97 iowrite32(counter, priv->iobase + HW_WDTC);
98
99 return 0;
100}
101
102static int asm9260_wdt_enable(struct watchdog_device *wdd)
103{
104 struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
105 u32 mode = 0;
106
107 if (priv->mode == HW_RESET)
108 mode = BM_MOD_WDRESET;
109
110 iowrite32(BM_MOD_WDEN | mode, priv->iobase + HW_WDMOD);
111
112 asm9260_wdt_updatetimeout(wdd);
113
114 asm9260_wdt_feed(wdd);
115
116 return 0;
117}
118
119static int asm9260_wdt_disable(struct watchdog_device *wdd)
120{
121 struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
122
123 /* The only way to disable WD is to reset it. */
124 reset_control_assert(priv->rst);
125 reset_control_deassert(priv->rst);
126
127 return 0;
128}
129
130static int asm9260_wdt_settimeout(struct watchdog_device *wdd, unsigned int to)
131{
132 wdd->timeout = to;
133 asm9260_wdt_updatetimeout(wdd);
134
135 return 0;
136}
137
138static void asm9260_wdt_sys_reset(struct asm9260_wdt_priv *priv)
139{
140 /* init WD if it was not started */
141
142 iowrite32(BM_MOD_WDEN | BM_MOD_WDRESET, priv->iobase + HW_WDMOD);
143
144 iowrite32(0xff, priv->iobase + HW_WDTC);
145 /* first pass correct sequence */
146 asm9260_wdt_feed(&priv->wdd);
147 /*
148 * Then write wrong pattern to the feed to trigger reset
149 * ASAP.
150 */
151 iowrite32(0xff, priv->iobase + HW_WDFEED);
152
153 mdelay(1000);
154}
155
156static irqreturn_t asm9260_wdt_irq(int irq, void *devid)
157{
158 struct asm9260_wdt_priv *priv = devid;
159 u32 stat;
160
161 stat = ioread32(priv->iobase + HW_WDMOD);
162 if (!(stat & BM_MOD_WDINT))
163 return IRQ_NONE;
164
165 if (priv->mode == DEBUG) {
166 dev_info(priv->dev, "Watchdog Timeout. Do nothing.\n");
167 } else {
168 dev_info(priv->dev, "Watchdog Timeout. Doing SW Reset.\n");
169 asm9260_wdt_sys_reset(priv);
170 }
171
172 return IRQ_HANDLED;
173}
174
175static int asm9260_restart_handler(struct notifier_block *this,
176 unsigned long mode, void *cmd)
177{
178 struct asm9260_wdt_priv *priv =
179 container_of(this, struct asm9260_wdt_priv, restart_handler);
180
181 asm9260_wdt_sys_reset(priv);
182
183 return NOTIFY_DONE;
184}
185
186static const struct watchdog_info asm9260_wdt_ident = {
187 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING
188 | WDIOF_MAGICCLOSE,
189 .identity = "Alphascale asm9260 Watchdog",
190};
191
192static struct watchdog_ops asm9260_wdt_ops = {
193 .owner = THIS_MODULE,
194 .start = asm9260_wdt_enable,
195 .stop = asm9260_wdt_disable,
196 .get_timeleft = asm9260_wdt_gettimeleft,
197 .ping = asm9260_wdt_feed,
198 .set_timeout = asm9260_wdt_settimeout,
199};
200
201static int asm9260_wdt_get_dt_clks(struct asm9260_wdt_priv *priv)
202{
203 int err;
204 unsigned long clk;
205
206 priv->clk = devm_clk_get(priv->dev, "mod");
207 if (IS_ERR(priv->clk)) {
208 dev_err(priv->dev, "Failed to get \"mod\" clk\n");
209 return PTR_ERR(priv->clk);
210 }
211
212 /* configure AHB clock */
213 priv->clk_ahb = devm_clk_get(priv->dev, "ahb");
214 if (IS_ERR(priv->clk_ahb)) {
215 dev_err(priv->dev, "Failed to get \"ahb\" clk\n");
216 return PTR_ERR(priv->clk_ahb);
217 }
218
219 err = clk_prepare_enable(priv->clk_ahb);
220 if (err) {
221 dev_err(priv->dev, "Failed to enable ahb_clk!\n");
222 return err;
223 }
224
225 err = clk_set_rate(priv->clk, CLOCK_FREQ);
226 if (err) {
227 clk_disable_unprepare(priv->clk_ahb);
228 dev_err(priv->dev, "Failed to set rate!\n");
229 return err;
230 }
231
232 err = clk_prepare_enable(priv->clk);
233 if (err) {
234 clk_disable_unprepare(priv->clk_ahb);
235 dev_err(priv->dev, "Failed to enable clk!\n");
236 return err;
237 }
238
239 /* wdt has internal divider */
240 clk = clk_get_rate(priv->clk);
241 if (!clk) {
242 clk_disable_unprepare(priv->clk);
243 clk_disable_unprepare(priv->clk_ahb);
244 dev_err(priv->dev, "Failed, clk is 0!\n");
245 return -EINVAL;
246 }
247
248 priv->wdt_freq = clk / 2;
249
250 return 0;
251}
252
253static void asm9260_wdt_get_dt_mode(struct asm9260_wdt_priv *priv)
254{
255 const char *tmp;
256 int ret;
257
258 /* default mode */
259 priv->mode = HW_RESET;
260
261 ret = of_property_read_string(priv->dev->of_node,
262 "alphascale,mode", &tmp);
263 if (ret < 0)
264 return;
265
266 if (!strcmp(tmp, "hw"))
267 priv->mode = HW_RESET;
268 else if (!strcmp(tmp, "sw"))
269 priv->mode = SW_RESET;
270 else if (!strcmp(tmp, "debug"))
271 priv->mode = DEBUG;
272 else
273 dev_warn(priv->dev, "unknown reset-type: %s. Using default \"hw\" mode.",
274 tmp);
275}
276
277static int asm9260_wdt_probe(struct platform_device *pdev)
278{
279 struct asm9260_wdt_priv *priv;
280 struct watchdog_device *wdd;
281 struct resource *res;
282 int ret;
283 const char * const mode_name[] = { "hw", "sw", "debug", };
284
285 priv = devm_kzalloc(&pdev->dev, sizeof(struct asm9260_wdt_priv),
286 GFP_KERNEL);
287 if (!priv)
288 return -ENOMEM;
289
290 priv->dev = &pdev->dev;
291
292 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
293 priv->iobase = devm_ioremap_resource(&pdev->dev, res);
294 if (IS_ERR(priv->iobase))
295 return PTR_ERR(priv->iobase);
296
297 ret = asm9260_wdt_get_dt_clks(priv);
298 if (ret)
299 return ret;
300
301 priv->rst = devm_reset_control_get(&pdev->dev, "wdt_rst");
302 if (IS_ERR(priv->rst))
303 return PTR_ERR(priv->rst);
304
305 wdd = &priv->wdd;
306 wdd->info = &asm9260_wdt_ident;
307 wdd->ops = &asm9260_wdt_ops;
308 wdd->min_timeout = 1;
309 wdd->max_timeout = BM_WDTC_MAX(priv->wdt_freq);
310 wdd->parent = &pdev->dev;
311
312 watchdog_set_drvdata(wdd, priv);
313
314 /*
315 * If 'timeout-sec' unspecified in devicetree, assume a 30 second
316 * default, unless the max timeout is less than 30 seconds, then use
317 * the max instead.
318 */
319 wdd->timeout = ASM9260_WDT_DEFAULT_TIMEOUT;
320 watchdog_init_timeout(wdd, 0, &pdev->dev);
321
322 asm9260_wdt_get_dt_mode(priv);
323
324 if (priv->mode != HW_RESET)
325 priv->irq = platform_get_irq(pdev, 0);
326
327 if (priv->irq > 0) {
328 /*
329 * Not all supported platforms specify an interrupt for the
330 * watchdog, so let's make it optional.
331 */
332 ret = devm_request_irq(&pdev->dev, priv->irq,
333 asm9260_wdt_irq, 0, pdev->name, priv);
334 if (ret < 0)
335 dev_warn(&pdev->dev, "failed to request IRQ\n");
336 }
337
338 ret = watchdog_register_device(wdd);
339 if (ret)
340 goto clk_off;
341
342 platform_set_drvdata(pdev, priv);
343
344 priv->restart_handler.notifier_call = asm9260_restart_handler;
345 priv->restart_handler.priority = 128;
346 ret = register_restart_handler(&priv->restart_handler);
347 if (ret)
348 dev_warn(&pdev->dev, "cannot register restart handler\n");
349
350 dev_info(&pdev->dev, "Watchdog enabled (timeout: %d sec, mode: %s)\n",
351 wdd->timeout, mode_name[priv->mode]);
352 return 0;
353
354clk_off:
355 clk_disable_unprepare(priv->clk);
356 clk_disable_unprepare(priv->clk_ahb);
357 return ret;
358}
359
360static void asm9260_wdt_shutdown(struct platform_device *pdev)
361{
362 struct asm9260_wdt_priv *priv = platform_get_drvdata(pdev);
363
364 asm9260_wdt_disable(&priv->wdd);
365}
366
367static int asm9260_wdt_remove(struct platform_device *pdev)
368{
369 struct asm9260_wdt_priv *priv = platform_get_drvdata(pdev);
370
371 asm9260_wdt_disable(&priv->wdd);
372
373 unregister_restart_handler(&priv->restart_handler);
374
375 watchdog_unregister_device(&priv->wdd);
376
377 clk_disable_unprepare(priv->clk);
378 clk_disable_unprepare(priv->clk_ahb);
379
380 return 0;
381}
382
383static const struct of_device_id asm9260_wdt_of_match[] = {
384 { .compatible = "alphascale,asm9260-wdt"},
385 {},
386};
387MODULE_DEVICE_TABLE(of, asm9260_wdt_of_match);
388
389static struct platform_driver asm9260_wdt_driver = {
390 .driver = {
391 .name = "asm9260-wdt",
392 .owner = THIS_MODULE,
393 .of_match_table = asm9260_wdt_of_match,
394 },
395 .probe = asm9260_wdt_probe,
396 .remove = asm9260_wdt_remove,
397 .shutdown = asm9260_wdt_shutdown,
398};
399module_platform_driver(asm9260_wdt_driver);
400
401MODULE_DESCRIPTION("asm9260 WatchDog Timer Driver");
402MODULE_AUTHOR("Oleksij Rempel <linux@rempel-privat.de>");
403MODULE_LICENSE("GPL");