2 * Watchdog driver for Renesas WDT watchdog
4 * Copyright (C) 2015-17 Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
5 * Copyright (C) 2015-17 Renesas Electronics Corporation
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License version 2 as published by
9 * the Free Software Foundation.
11 #include <linux/bitops.h>
12 #include <linux/clk.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
17 #include <linux/platform_device.h>
18 #include <linux/pm_runtime.h>
19 #include <linux/smp.h>
20 #include <linux/sys_soc.h>
21 #include <linux/watchdog.h>
25 #define RWTCSRA_WOVF BIT(4)
26 #define RWTCSRA_WRFLG BIT(5)
27 #define RWTCSRA_TME BIT(7)
30 #define RWDT_DEFAULT_TIMEOUT 60U
33 * In probe, clk_rate is checked to be not more than 16 bit * biggest clock
34 * divider (12 bits). d is only a factor to fully utilize the WDT counter and
35 * will not exceed its 16 bits. Thus, no overflow, we stay below 32 bits.
37 #define MUL_BY_CLKS_PER_SEC(p, d) \
38 DIV_ROUND_UP((d) * (p)->clk_rate, clk_divs[(p)->cks])
40 /* d is 16 bit, clk_divs 12 bit -> no 32 bit overflow */
41 #define DIV_BY_CLKS_PER_SEC(p, d) ((d) * clk_divs[(p)->cks] / (p)->clk_rate)
43 static const unsigned int clk_divs[] = { 1, 4, 16, 32, 64, 128, 1024, 4096 };
45 static bool nowayout = WATCHDOG_NOWAYOUT;
46 module_param(nowayout, bool, 0);
47 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
48 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
52 struct watchdog_device wdev;
53 unsigned long clk_rate;
58 static void rwdt_write(struct rwdt_priv *priv, u32 val, unsigned int reg)
65 writel_relaxed(val, priv->base + reg);
68 static int rwdt_init_timeout(struct watchdog_device *wdev)
70 struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
72 rwdt_write(priv, 65536 - MUL_BY_CLKS_PER_SEC(priv, wdev->timeout), RWTCNT);
77 static int rwdt_start(struct watchdog_device *wdev)
79 struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
81 pm_runtime_get_sync(wdev->parent);
83 rwdt_write(priv, 0, RWTCSRB);
84 rwdt_write(priv, priv->cks, RWTCSRA);
85 rwdt_init_timeout(wdev);
87 while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG)
90 rwdt_write(priv, priv->cks | RWTCSRA_TME, RWTCSRA);
95 static int rwdt_stop(struct watchdog_device *wdev)
97 struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
99 rwdt_write(priv, priv->cks, RWTCSRA);
100 pm_runtime_put(wdev->parent);
105 static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev)
107 struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
108 u16 val = readw_relaxed(priv->base + RWTCNT);
110 return DIV_BY_CLKS_PER_SEC(priv, 65536 - val);
113 static const struct watchdog_info rwdt_ident = {
114 .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
115 .identity = "Renesas WDT Watchdog",
118 static const struct watchdog_ops rwdt_ops = {
119 .owner = THIS_MODULE,
122 .ping = rwdt_init_timeout,
123 .get_timeleft = rwdt_get_timeleft,
126 #if defined(CONFIG_ARCH_RCAR_GEN2) && defined(CONFIG_SMP)
128 * Watchdog-reset integration is broken on early revisions of R-Car Gen2 SoCs
130 static const struct soc_device_attribute rwdt_quirks_match[] = {
134 .data = (void *)1, /* needs single CPU */
137 .revision = "ES[12].*",
138 .data = (void *)1, /* needs single CPU */
142 .data = (void *)0, /* needs SMP disabled */
147 static bool rwdt_blacklisted(struct device *dev)
149 const struct soc_device_attribute *attr;
151 attr = soc_device_match(rwdt_quirks_match);
152 if (attr && setup_max_cpus > (uintptr_t)attr->data) {
153 dev_info(dev, "Watchdog blacklisted on %s %s\n", attr->soc_id,
160 #else /* !CONFIG_ARCH_RCAR_GEN2 || !CONFIG_SMP */
161 static inline bool rwdt_blacklisted(struct device *dev) { return false; }
162 #endif /* !CONFIG_ARCH_RCAR_GEN2 || !CONFIG_SMP */
164 static int rwdt_probe(struct platform_device *pdev)
166 struct rwdt_priv *priv;
167 struct resource *res;
169 unsigned long clks_per_sec;
172 if (rwdt_blacklisted(&pdev->dev))
175 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
179 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
180 priv->base = devm_ioremap_resource(&pdev->dev, res);
181 if (IS_ERR(priv->base))
182 return PTR_ERR(priv->base);
184 clk = devm_clk_get(&pdev->dev, NULL);
188 pm_runtime_enable(&pdev->dev);
190 pm_runtime_get_sync(&pdev->dev);
191 priv->clk_rate = clk_get_rate(clk);
192 pm_runtime_put(&pdev->dev);
194 if (!priv->clk_rate) {
199 for (i = ARRAY_SIZE(clk_divs) - 1; i >= 0; i--) {
200 clks_per_sec = priv->clk_rate / clk_divs[i];
201 if (clks_per_sec && clks_per_sec < 65536) {
208 dev_err(&pdev->dev, "Can't find suitable clock divider\n");
213 priv->wdev.info = &rwdt_ident,
214 priv->wdev.ops = &rwdt_ops,
215 priv->wdev.parent = &pdev->dev;
216 priv->wdev.min_timeout = 1;
217 priv->wdev.max_timeout = DIV_BY_CLKS_PER_SEC(priv, 65536);
218 priv->wdev.timeout = min(priv->wdev.max_timeout, RWDT_DEFAULT_TIMEOUT);
220 platform_set_drvdata(pdev, priv);
221 watchdog_set_drvdata(&priv->wdev, priv);
222 watchdog_set_nowayout(&priv->wdev, nowayout);
224 /* This overrides the default timeout only if DT configuration was found */
225 ret = watchdog_init_timeout(&priv->wdev, 0, &pdev->dev);
227 dev_warn(&pdev->dev, "Specified timeout value invalid, using default\n");
229 ret = watchdog_register_device(&priv->wdev);
236 pm_runtime_disable(&pdev->dev);
240 static int rwdt_remove(struct platform_device *pdev)
242 struct rwdt_priv *priv = platform_get_drvdata(pdev);
244 watchdog_unregister_device(&priv->wdev);
245 pm_runtime_disable(&pdev->dev);
250 static int __maybe_unused rwdt_suspend(struct device *dev)
252 struct rwdt_priv *priv = dev_get_drvdata(dev);
254 if (watchdog_active(&priv->wdev)) {
255 priv->time_left = readw(priv->base + RWTCNT);
256 rwdt_stop(&priv->wdev);
261 static int __maybe_unused rwdt_resume(struct device *dev)
263 struct rwdt_priv *priv = dev_get_drvdata(dev);
265 if (watchdog_active(&priv->wdev)) {
266 rwdt_start(&priv->wdev);
267 rwdt_write(priv, priv->time_left, RWTCNT);
272 static SIMPLE_DEV_PM_OPS(rwdt_pm_ops, rwdt_suspend, rwdt_resume);
274 static const struct of_device_id rwdt_ids[] = {
275 { .compatible = "renesas,rcar-gen2-wdt", },
276 { .compatible = "renesas,rcar-gen3-wdt", },
279 MODULE_DEVICE_TABLE(of, rwdt_ids);
281 static struct platform_driver rwdt_driver = {
283 .name = "renesas_wdt",
284 .of_match_table = rwdt_ids,
288 .remove = rwdt_remove,
290 module_platform_driver(rwdt_driver);
292 MODULE_DESCRIPTION("Renesas WDT Watchdog Driver");
293 MODULE_LICENSE("GPL v2");
294 MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");