1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Watchdog driver for CSR Atlas7
  4 *
  5 * Copyright (c) 2015 Cambridge Silicon Radio Limited, a CSR plc group company.
  6 */
  7
  8#include <linux/clk.h>
  9#include <linux/io.h>
 10#include <linux/module.h>
 11#include <linux/moduleparam.h>
 12#include <linux/of.h>
 13#include <linux/platform_device.h>
 14#include <linux/watchdog.h>
 15
 16#define ATLAS7_TIMER_WDT_INDEX		5
 17#define ATLAS7_WDT_DEFAULT_TIMEOUT	20
 18
 19#define ATLAS7_WDT_CNT_CTRL	(0 + 4 * ATLAS7_TIMER_WDT_INDEX)
 20#define ATLAS7_WDT_CNT_MATCH	(0x18 + 4 * ATLAS7_TIMER_WDT_INDEX)
 21#define ATLAS7_WDT_CNT		(0x48 +  4 * ATLAS7_TIMER_WDT_INDEX)
 22#define ATLAS7_WDT_CNT_EN	(BIT(0) | BIT(1))
 23#define ATLAS7_WDT_EN		0x64
 24
 25static unsigned int timeout = ATLAS7_WDT_DEFAULT_TIMEOUT;
 26static bool nowayout = WATCHDOG_NOWAYOUT;
 27
 28module_param(timeout, uint, 0);
 29module_param(nowayout, bool, 0);
 30
 31MODULE_PARM_DESC(timeout, "Default watchdog timeout (in seconds)");
 32MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 33			__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 34
 35struct atlas7_wdog {
 36	struct device *dev;
 37	void __iomem *base;
 38	unsigned long tick_rate;
 39	struct clk *clk;
 40};
 41
 42static unsigned int atlas7_wdt_gettimeleft(struct watchdog_device *wdd)
 43{
 44	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
 45	u32 counter, match, delta;
 46
 47	counter = readl(wdt->base + ATLAS7_WDT_CNT);
 48	match = readl(wdt->base + ATLAS7_WDT_CNT_MATCH);
 49	delta = match - counter;
 50
 51	return  delta / wdt->tick_rate;
 52}
 53
 54static int atlas7_wdt_ping(struct watchdog_device *wdd)
 55{
 56	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
 57	u32 counter, match, delta;
 58
 59	counter = readl(wdt->base + ATLAS7_WDT_CNT);
 60	delta = wdd->timeout * wdt->tick_rate;
 61	match = counter + delta;
 62
 63	writel(match, wdt->base + ATLAS7_WDT_CNT_MATCH);
 64
 65	return 0;
 66}
 67
 68static int atlas7_wdt_enable(struct watchdog_device *wdd)
 69{
 70	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
 71
 72	atlas7_wdt_ping(wdd);
 73
 74	writel(readl(wdt->base + ATLAS7_WDT_CNT_CTRL) | ATLAS7_WDT_CNT_EN,
 75	      wdt->base + ATLAS7_WDT_CNT_CTRL);
 76	writel(1, wdt->base + ATLAS7_WDT_EN);
 77
 78	return 0;
 79}
 80
 81static int atlas7_wdt_disable(struct watchdog_device *wdd)
 82{
 83	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
 84
 85	writel(0, wdt->base + ATLAS7_WDT_EN);
 86	writel(readl(wdt->base + ATLAS7_WDT_CNT_CTRL) & ~ATLAS7_WDT_CNT_EN,
 87	      wdt->base + ATLAS7_WDT_CNT_CTRL);
 88
 89	return 0;
 90}
 91
 92static int atlas7_wdt_settimeout(struct watchdog_device *wdd, unsigned int to)
 93{
 94	wdd->timeout = to;
 95
 96	return 0;
 97}
 98
 99#define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
100
101static const struct watchdog_info atlas7_wdt_ident = {
102	.options = OPTIONS,
103	.firmware_version = 0,
104	.identity = "atlas7 Watchdog",
105};
106
107static const struct watchdog_ops atlas7_wdt_ops = {
108	.owner = THIS_MODULE,
109	.start = atlas7_wdt_enable,
110	.stop = atlas7_wdt_disable,
111	.get_timeleft = atlas7_wdt_gettimeleft,
112	.ping = atlas7_wdt_ping,
113	.set_timeout = atlas7_wdt_settimeout,
114};
115
116static struct watchdog_device atlas7_wdd = {
117	.info = &atlas7_wdt_ident,
118	.ops = &atlas7_wdt_ops,
119	.timeout = ATLAS7_WDT_DEFAULT_TIMEOUT,
120};
121
122static const struct of_device_id atlas7_wdt_ids[] = {
123	{ .compatible = "sirf,atlas7-tick"},
124	{}
125};
126
127static void atlas7_clk_disable_unprepare(void *data)
128{
129	clk_disable_unprepare(data);
130}
131
132static int atlas7_wdt_probe(struct platform_device *pdev)
133{
134	struct device *dev = &pdev->dev;
135	struct atlas7_wdog *wdt;
136	struct clk *clk;
137	int ret;
138
139	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
140	if (!wdt)
141		return -ENOMEM;
142	wdt->base = devm_platform_ioremap_resource(pdev, 0);
143	if (IS_ERR(wdt->base))
144		return PTR_ERR(wdt->base);
145
146	clk = devm_clk_get(dev, NULL);
147	if (IS_ERR(clk))
148		return PTR_ERR(clk);
149	ret = clk_prepare_enable(clk);
150	if (ret) {
151		dev_err(dev, "clk enable failed\n");
152		return ret;
153	}
154	ret = devm_add_action_or_reset(dev, atlas7_clk_disable_unprepare, clk);
155	if (ret)
156		return ret;
157
158	/* disable watchdog hardware */
159	writel(0, wdt->base + ATLAS7_WDT_CNT_CTRL);
160
161	wdt->tick_rate = clk_get_rate(clk);
162	if (!wdt->tick_rate)
163		return -EINVAL;
164
165	wdt->clk = clk;
166	atlas7_wdd.min_timeout = 1;
167	atlas7_wdd.max_timeout = UINT_MAX / wdt->tick_rate;
168
169	watchdog_init_timeout(&atlas7_wdd, 0, dev);
170	watchdog_set_nowayout(&atlas7_wdd, nowayout);
171
172	watchdog_set_drvdata(&atlas7_wdd, wdt);
173	platform_set_drvdata(pdev, &atlas7_wdd);
174
175	watchdog_stop_on_reboot(&atlas7_wdd);
176	watchdog_stop_on_unregister(&atlas7_wdd);
177	return devm_watchdog_register_device(dev, &atlas7_wdd);
178}
179
180static int __maybe_unused atlas7_wdt_suspend(struct device *dev)
181{
182	/*
183	 * NOTE:timer controller registers settings are saved
184	 * and restored back by the timer-atlas7.c
185	 */
186	return 0;
187}
188
189static int __maybe_unused atlas7_wdt_resume(struct device *dev)
190{
191	struct watchdog_device *wdd = dev_get_drvdata(dev);
192
193	/*
194	 * NOTE: Since timer controller registers settings are saved
195	 * and restored back by the timer-atlas7.c, so we need not
196	 * update WD settings except refreshing timeout.
197	 */
198	atlas7_wdt_ping(wdd);
199
200	return 0;
201}
202
203static SIMPLE_DEV_PM_OPS(atlas7_wdt_pm_ops,
204		atlas7_wdt_suspend, atlas7_wdt_resume);
205
206MODULE_DEVICE_TABLE(of, atlas7_wdt_ids);
207
208static struct platform_driver atlas7_wdt_driver = {
209	.driver = {
210		.name = "atlas7-wdt",
211		.pm = &atlas7_wdt_pm_ops,
212		.of_match_table	= atlas7_wdt_ids,
213	},
214	.probe = atlas7_wdt_probe,
215};
216module_platform_driver(atlas7_wdt_driver);
217
218MODULE_DESCRIPTION("CSRatlas7 watchdog driver");
219MODULE_AUTHOR("Guo Zeng <Guo.Zeng@csr.com>");
220MODULE_LICENSE("GPL v2");
221MODULE_ALIAS("platform:atlas7-wdt");