2 * Watchdog driver for Alphascale ASM9260.
4 * Copyright (c) 2014 Oleksij Rempel <linux@rempel-privat.de>
6 * Licensed under GPLv2 or later.
9 #include <linux/bitops.h>
10 #include <linux/clk.h>
11 #include <linux/delay.h>
12 #include <linux/interrupt.h>
14 #include <linux/module.h>
16 #include <linux/platform_device.h>
17 #include <linux/reset.h>
18 #include <linux/watchdog.h>
20 #define CLOCK_FREQ 1000000
22 /* Watchdog Mode register */
24 /* Wake interrupt. Set by HW, can't be cleared. */
25 #define BM_MOD_WDINT BIT(3)
26 /* This bit set if timeout reached. Cleared by SW. */
27 #define BM_MOD_WDTOF BIT(2)
28 /* HW Reset on timeout */
29 #define BM_MOD_WDRESET BIT(1)
31 #define BM_MOD_WDEN BIT(0)
34 * Watchdog Timer Constant register
35 * Minimal value is 0xff, the meaning of this value
36 * depends on used clock: T = WDCLK * (0xff + 1) * 4
39 #define BM_WDTC_MAX(freq) (0x7fffffff / (freq))
41 /* Watchdog Feed register */
42 #define HW_WDFEED 0x08
44 /* Watchdog Timer Value register */
47 #define ASM9260_WDT_DEFAULT_TIMEOUT 30
49 enum asm9260_wdt_mode {
55 struct asm9260_wdt_priv {
57 struct watchdog_device wdd;
60 struct reset_control *rst;
64 unsigned long wdt_freq;
65 enum asm9260_wdt_mode mode;
68 static int asm9260_wdt_feed(struct watchdog_device *wdd)
70 struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
72 iowrite32(0xaa, priv->iobase + HW_WDFEED);
73 iowrite32(0x55, priv->iobase + HW_WDFEED);
78 static unsigned int asm9260_wdt_gettimeleft(struct watchdog_device *wdd)
80 struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
83 counter = ioread32(priv->iobase + HW_WDTV);
85 return counter / priv->wdt_freq;
88 static int asm9260_wdt_updatetimeout(struct watchdog_device *wdd)
90 struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
93 counter = wdd->timeout * priv->wdt_freq;
95 iowrite32(counter, priv->iobase + HW_WDTC);
100 static int asm9260_wdt_enable(struct watchdog_device *wdd)
102 struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
105 if (priv->mode == HW_RESET)
106 mode = BM_MOD_WDRESET;
108 iowrite32(BM_MOD_WDEN | mode, priv->iobase + HW_WDMOD);
110 asm9260_wdt_updatetimeout(wdd);
112 asm9260_wdt_feed(wdd);
117 static int asm9260_wdt_disable(struct watchdog_device *wdd)
119 struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
121 /* The only way to disable WD is to reset it. */
122 reset_control_assert(priv->rst);
123 reset_control_deassert(priv->rst);
128 static int asm9260_wdt_settimeout(struct watchdog_device *wdd, unsigned int to)
131 asm9260_wdt_updatetimeout(wdd);
136 static void asm9260_wdt_sys_reset(struct asm9260_wdt_priv *priv)
138 /* init WD if it was not started */
140 iowrite32(BM_MOD_WDEN | BM_MOD_WDRESET, priv->iobase + HW_WDMOD);
142 iowrite32(0xff, priv->iobase + HW_WDTC);
143 /* first pass correct sequence */
144 asm9260_wdt_feed(&priv->wdd);
146 * Then write wrong pattern to the feed to trigger reset
149 iowrite32(0xff, priv->iobase + HW_WDFEED);
154 static irqreturn_t asm9260_wdt_irq(int irq, void *devid)
156 struct asm9260_wdt_priv *priv = devid;
159 stat = ioread32(priv->iobase + HW_WDMOD);
160 if (!(stat & BM_MOD_WDINT))
163 if (priv->mode == DEBUG) {
164 dev_info(priv->dev, "Watchdog Timeout. Do nothing.\n");
166 dev_info(priv->dev, "Watchdog Timeout. Doing SW Reset.\n");
167 asm9260_wdt_sys_reset(priv);
173 static int asm9260_restart(struct watchdog_device *wdd, unsigned long action,
176 struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
178 asm9260_wdt_sys_reset(priv);
183 static const struct watchdog_info asm9260_wdt_ident = {
184 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING
186 .identity = "Alphascale asm9260 Watchdog",
189 static const struct watchdog_ops asm9260_wdt_ops = {
190 .owner = THIS_MODULE,
191 .start = asm9260_wdt_enable,
192 .stop = asm9260_wdt_disable,
193 .get_timeleft = asm9260_wdt_gettimeleft,
194 .ping = asm9260_wdt_feed,
195 .set_timeout = asm9260_wdt_settimeout,
196 .restart = asm9260_restart,
199 static int asm9260_wdt_get_dt_clks(struct asm9260_wdt_priv *priv)
204 priv->clk = devm_clk_get(priv->dev, "mod");
205 if (IS_ERR(priv->clk)) {
206 dev_err(priv->dev, "Failed to get \"mod\" clk\n");
207 return PTR_ERR(priv->clk);
210 /* configure AHB clock */
211 priv->clk_ahb = devm_clk_get(priv->dev, "ahb");
212 if (IS_ERR(priv->clk_ahb)) {
213 dev_err(priv->dev, "Failed to get \"ahb\" clk\n");
214 return PTR_ERR(priv->clk_ahb);
217 err = clk_prepare_enable(priv->clk_ahb);
219 dev_err(priv->dev, "Failed to enable ahb_clk!\n");
223 err = clk_set_rate(priv->clk, CLOCK_FREQ);
225 clk_disable_unprepare(priv->clk_ahb);
226 dev_err(priv->dev, "Failed to set rate!\n");
230 err = clk_prepare_enable(priv->clk);
232 clk_disable_unprepare(priv->clk_ahb);
233 dev_err(priv->dev, "Failed to enable clk!\n");
237 /* wdt has internal divider */
238 clk = clk_get_rate(priv->clk);
240 clk_disable_unprepare(priv->clk);
241 clk_disable_unprepare(priv->clk_ahb);
242 dev_err(priv->dev, "Failed, clk is 0!\n");
246 priv->wdt_freq = clk / 2;
251 static void asm9260_wdt_get_dt_mode(struct asm9260_wdt_priv *priv)
257 priv->mode = HW_RESET;
259 ret = of_property_read_string(priv->dev->of_node,
260 "alphascale,mode", &tmp);
264 if (!strcmp(tmp, "hw"))
265 priv->mode = HW_RESET;
266 else if (!strcmp(tmp, "sw"))
267 priv->mode = SW_RESET;
268 else if (!strcmp(tmp, "debug"))
271 dev_warn(priv->dev, "unknown reset-type: %s. Using default \"hw\" mode.",
275 static int asm9260_wdt_probe(struct platform_device *pdev)
277 struct asm9260_wdt_priv *priv;
278 struct watchdog_device *wdd;
280 static const char * const mode_name[] = { "hw", "sw", "debug", };
282 priv = devm_kzalloc(&pdev->dev, sizeof(struct asm9260_wdt_priv),
287 priv->dev = &pdev->dev;
289 priv->iobase = devm_platform_ioremap_resource(pdev, 0);
290 if (IS_ERR(priv->iobase))
291 return PTR_ERR(priv->iobase);
293 priv->rst = devm_reset_control_get_exclusive(&pdev->dev, "wdt_rst");
294 if (IS_ERR(priv->rst))
295 return PTR_ERR(priv->rst);
297 ret = asm9260_wdt_get_dt_clks(priv);
302 wdd->info = &asm9260_wdt_ident;
303 wdd->ops = &asm9260_wdt_ops;
304 wdd->min_timeout = 1;
305 wdd->max_timeout = BM_WDTC_MAX(priv->wdt_freq);
306 wdd->parent = &pdev->dev;
308 watchdog_set_drvdata(wdd, priv);
311 * If 'timeout-sec' unspecified in devicetree, assume a 30 second
312 * default, unless the max timeout is less than 30 seconds, then use
315 wdd->timeout = ASM9260_WDT_DEFAULT_TIMEOUT;
316 watchdog_init_timeout(wdd, 0, &pdev->dev);
318 asm9260_wdt_get_dt_mode(priv);
320 if (priv->mode != HW_RESET)
321 priv->irq = platform_get_irq(pdev, 0);
325 * Not all supported platforms specify an interrupt for the
326 * watchdog, so let's make it optional.
328 ret = devm_request_irq(&pdev->dev, priv->irq,
329 asm9260_wdt_irq, 0, pdev->name, priv);
331 dev_warn(&pdev->dev, "failed to request IRQ\n");
334 watchdog_set_restart_priority(wdd, 128);
336 ret = watchdog_register_device(wdd);
340 platform_set_drvdata(pdev, priv);
342 dev_info(&pdev->dev, "Watchdog enabled (timeout: %d sec, mode: %s)\n",
343 wdd->timeout, mode_name[priv->mode]);
347 clk_disable_unprepare(priv->clk);
348 clk_disable_unprepare(priv->clk_ahb);
352 static void asm9260_wdt_shutdown(struct platform_device *pdev)
354 struct asm9260_wdt_priv *priv = platform_get_drvdata(pdev);
356 asm9260_wdt_disable(&priv->wdd);
359 static int asm9260_wdt_remove(struct platform_device *pdev)
361 struct asm9260_wdt_priv *priv = platform_get_drvdata(pdev);
363 asm9260_wdt_disable(&priv->wdd);
365 watchdog_unregister_device(&priv->wdd);
367 clk_disable_unprepare(priv->clk);
368 clk_disable_unprepare(priv->clk_ahb);
373 static const struct of_device_id asm9260_wdt_of_match[] = {
374 { .compatible = "alphascale,asm9260-wdt"},
377 MODULE_DEVICE_TABLE(of, asm9260_wdt_of_match);
379 static struct platform_driver asm9260_wdt_driver = {
381 .name = "asm9260-wdt",
382 .of_match_table = asm9260_wdt_of_match,
384 .probe = asm9260_wdt_probe,
385 .remove = asm9260_wdt_remove,
386 .shutdown = asm9260_wdt_shutdown,
388 module_platform_driver(asm9260_wdt_driver);
390 MODULE_DESCRIPTION("asm9260 WatchDog Timer Driver");
391 MODULE_AUTHOR("Oleksij Rempel <linux@rempel-privat.de>");
392 MODULE_LICENSE("GPL");