1 // SPDX-License-Identifier: GPL-2.0
3 * Watchdog driver for Renesas WDT watchdog
5 * Copyright (C) 2015-17 Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
6 * Copyright (C) 2015-17 Renesas Electronics Corporation
8 #include <linux/bitops.h>
11 #include <linux/kernel.h>
12 #include <linux/module.h>
14 #include <linux/platform_device.h>
15 #include <linux/pm_runtime.h>
16 #include <linux/smp.h>
17 #include <linux/sys_soc.h>
18 #include <linux/watchdog.h>
22 #define RWTCSRA_WOVF BIT(4)
23 #define RWTCSRA_WRFLG BIT(5)
24 #define RWTCSRA_TME BIT(7)
27 #define RWDT_DEFAULT_TIMEOUT 60U
30 * In probe, clk_rate is checked to be not more than 16 bit * biggest clock
31 * divider (12 bits). d is only a factor to fully utilize the WDT counter and
32 * will not exceed its 16 bits. Thus, no overflow, we stay below 32 bits.
34 #define MUL_BY_CLKS_PER_SEC(p, d) \
35 DIV_ROUND_UP((d) * (p)->clk_rate, clk_divs[(p)->cks])
37 /* d is 16 bit, clk_divs 12 bit -> no 32 bit overflow */
38 #define DIV_BY_CLKS_PER_SEC(p, d) ((d) * clk_divs[(p)->cks] / (p)->clk_rate)
40 static const unsigned int clk_divs[] = { 1, 4, 16, 32, 64, 128, 1024, 4096 };
42 static bool nowayout = WATCHDOG_NOWAYOUT;
43 module_param(nowayout, bool, 0);
44 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
45 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
49 struct watchdog_device wdev;
50 unsigned long clk_rate;
54 static void rwdt_write(struct rwdt_priv *priv, u32 val, unsigned int reg)
61 writel_relaxed(val, priv->base + reg);
64 static int rwdt_init_timeout(struct watchdog_device *wdev)
66 struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
68 rwdt_write(priv, 65536 - MUL_BY_CLKS_PER_SEC(priv, wdev->timeout), RWTCNT);
73 static int rwdt_start(struct watchdog_device *wdev)
75 struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
78 pm_runtime_get_sync(wdev->parent);
80 /* Stop the timer before we modify any register */
81 val = readb_relaxed(priv->base + RWTCSRA) & ~RWTCSRA_TME;
82 rwdt_write(priv, val, RWTCSRA);
84 rwdt_init_timeout(wdev);
85 rwdt_write(priv, priv->cks, RWTCSRA);
86 rwdt_write(priv, 0, RWTCSRB);
88 while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG)
91 rwdt_write(priv, priv->cks | RWTCSRA_TME, RWTCSRA);
96 static int rwdt_stop(struct watchdog_device *wdev)
98 struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
100 rwdt_write(priv, priv->cks, RWTCSRA);
101 pm_runtime_put(wdev->parent);
106 static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev)
108 struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
109 u16 val = readw_relaxed(priv->base + RWTCNT);
111 return DIV_BY_CLKS_PER_SEC(priv, 65536 - val);
114 static int rwdt_restart(struct watchdog_device *wdev, unsigned long action,
117 struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
120 rwdt_write(priv, 0xffff, RWTCNT);
124 static const struct watchdog_info rwdt_ident = {
125 .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
127 .identity = "Renesas WDT Watchdog",
130 static const struct watchdog_ops rwdt_ops = {
131 .owner = THIS_MODULE,
134 .ping = rwdt_init_timeout,
135 .get_timeleft = rwdt_get_timeleft,
136 .restart = rwdt_restart,
139 #if defined(CONFIG_ARCH_RCAR_GEN2) && defined(CONFIG_SMP)
141 * Watchdog-reset integration is broken on early revisions of R-Car Gen2 SoCs
143 static const struct soc_device_attribute rwdt_quirks_match[] = {
147 .data = (void *)1, /* needs single CPU */
151 .data = (void *)1, /* needs single CPU */
155 .data = (void *)0, /* needs SMP disabled */
160 static bool rwdt_blacklisted(struct device *dev)
162 const struct soc_device_attribute *attr;
164 attr = soc_device_match(rwdt_quirks_match);
165 if (attr && setup_max_cpus > (uintptr_t)attr->data) {
166 dev_info(dev, "Watchdog blacklisted on %s %s\n", attr->soc_id,
173 #else /* !CONFIG_ARCH_RCAR_GEN2 || !CONFIG_SMP */
174 static inline bool rwdt_blacklisted(struct device *dev) { return false; }
175 #endif /* !CONFIG_ARCH_RCAR_GEN2 || !CONFIG_SMP */
177 static int rwdt_probe(struct platform_device *pdev)
179 struct rwdt_priv *priv;
180 struct resource *res;
182 unsigned long clks_per_sec;
185 if (rwdt_blacklisted(&pdev->dev))
188 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
192 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
193 priv->base = devm_ioremap_resource(&pdev->dev, res);
194 if (IS_ERR(priv->base))
195 return PTR_ERR(priv->base);
197 clk = devm_clk_get(&pdev->dev, NULL);
201 pm_runtime_enable(&pdev->dev);
202 pm_runtime_get_sync(&pdev->dev);
203 priv->clk_rate = clk_get_rate(clk);
204 priv->wdev.bootstatus = (readb_relaxed(priv->base + RWTCSRA) &
205 RWTCSRA_WOVF) ? WDIOF_CARDRESET : 0;
206 pm_runtime_put(&pdev->dev);
208 if (!priv->clk_rate) {
213 for (i = ARRAY_SIZE(clk_divs) - 1; i >= 0; i--) {
214 clks_per_sec = priv->clk_rate / clk_divs[i];
215 if (clks_per_sec && clks_per_sec < 65536) {
222 dev_err(&pdev->dev, "Can't find suitable clock divider\n");
227 priv->wdev.info = &rwdt_ident;
228 priv->wdev.ops = &rwdt_ops;
229 priv->wdev.parent = &pdev->dev;
230 priv->wdev.min_timeout = 1;
231 priv->wdev.max_timeout = DIV_BY_CLKS_PER_SEC(priv, 65536);
232 priv->wdev.timeout = min(priv->wdev.max_timeout, RWDT_DEFAULT_TIMEOUT);
234 platform_set_drvdata(pdev, priv);
235 watchdog_set_drvdata(&priv->wdev, priv);
236 watchdog_set_nowayout(&priv->wdev, nowayout);
237 watchdog_set_restart_priority(&priv->wdev, 0);
238 watchdog_stop_on_unregister(&priv->wdev);
240 /* This overrides the default timeout only if DT configuration was found */
241 ret = watchdog_init_timeout(&priv->wdev, 0, &pdev->dev);
243 dev_warn(&pdev->dev, "Specified timeout value invalid, using default\n");
245 ret = watchdog_register_device(&priv->wdev);
252 pm_runtime_disable(&pdev->dev);
256 static int rwdt_remove(struct platform_device *pdev)
258 struct rwdt_priv *priv = platform_get_drvdata(pdev);
260 watchdog_unregister_device(&priv->wdev);
261 pm_runtime_disable(&pdev->dev);
266 static int __maybe_unused rwdt_suspend(struct device *dev)
268 struct rwdt_priv *priv = dev_get_drvdata(dev);
270 if (watchdog_active(&priv->wdev))
271 rwdt_stop(&priv->wdev);
276 static int __maybe_unused rwdt_resume(struct device *dev)
278 struct rwdt_priv *priv = dev_get_drvdata(dev);
280 if (watchdog_active(&priv->wdev))
281 rwdt_start(&priv->wdev);
286 static SIMPLE_DEV_PM_OPS(rwdt_pm_ops, rwdt_suspend, rwdt_resume);
288 static const struct of_device_id rwdt_ids[] = {
289 { .compatible = "renesas,rcar-gen2-wdt", },
290 { .compatible = "renesas,rcar-gen3-wdt", },
293 MODULE_DEVICE_TABLE(of, rwdt_ids);
295 static struct platform_driver rwdt_driver = {
297 .name = "renesas_wdt",
298 .of_match_table = rwdt_ids,
302 .remove = rwdt_remove,
304 module_platform_driver(rwdt_driver);
306 MODULE_DESCRIPTION("Renesas WDT Watchdog Driver");
307 MODULE_LICENSE("GPL v2");
308 MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");