1/*
  2 * Watchdog driver for CSR Atlas7
  3 *
  4 * Copyright (c) 2015 Cambridge Silicon Radio Limited, a CSR plc group company.
  5 *
  6 * Licensed under GPLv2.
  7 */
  8
  9#include <linux/clk.h>
 10#include <linux/io.h>
 11#include <linux/module.h>
 12#include <linux/moduleparam.h>
 13#include <linux/of.h>
 14#include <linux/platform_device.h>
 15#include <linux/watchdog.h>
 16
 17#define ATLAS7_TIMER_WDT_INDEX		5
 18#define ATLAS7_WDT_DEFAULT_TIMEOUT	20
 19
 20#define ATLAS7_WDT_CNT_CTRL	(0 + 4 * ATLAS7_TIMER_WDT_INDEX)
 21#define ATLAS7_WDT_CNT_MATCH	(0x18 + 4 * ATLAS7_TIMER_WDT_INDEX)
 22#define ATLAS7_WDT_CNT		(0x48 +  4 * ATLAS7_TIMER_WDT_INDEX)
 23#define ATLAS7_WDT_CNT_EN	(BIT(0) | BIT(1))
 24#define ATLAS7_WDT_EN		0x64
 25
 26static unsigned int timeout = ATLAS7_WDT_DEFAULT_TIMEOUT;
 27static bool nowayout = WATCHDOG_NOWAYOUT;
 28
 29module_param(timeout, uint, 0);
 30module_param(nowayout, bool, 0);
 31
 32MODULE_PARM_DESC(timeout, "Default watchdog timeout (in seconds)");
 33MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 34			__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 35
 36struct atlas7_wdog {
 37	struct device *dev;
 38	void __iomem *base;
 39	unsigned long tick_rate;
 40	struct clk *clk;
 41};
 42
 43static unsigned int atlas7_wdt_gettimeleft(struct watchdog_device *wdd)
 44{
 45	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
 46	u32 counter, match, delta;
 47
 48	counter = readl(wdt->base + ATLAS7_WDT_CNT);
 49	match = readl(wdt->base + ATLAS7_WDT_CNT_MATCH);
 50	delta = match - counter;
 51
 52	return  delta / wdt->tick_rate;
 53}
 54
 55static int atlas7_wdt_ping(struct watchdog_device *wdd)
 56{
 57	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
 58	u32 counter, match, delta;
 59
 60	counter = readl(wdt->base + ATLAS7_WDT_CNT);
 61	delta = wdd->timeout * wdt->tick_rate;
 62	match = counter + delta;
 63
 64	writel(match, wdt->base + ATLAS7_WDT_CNT_MATCH);
 65
 66	return 0;
 67}
 68
 69static int atlas7_wdt_enable(struct watchdog_device *wdd)
 70{
 71	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
 72
 73	atlas7_wdt_ping(wdd);
 74
 75	writel(readl(wdt->base + ATLAS7_WDT_CNT_CTRL) | ATLAS7_WDT_CNT_EN,
 76	      wdt->base + ATLAS7_WDT_CNT_CTRL);
 77	writel(1, wdt->base + ATLAS7_WDT_EN);
 78
 79	return 0;
 80}
 81
 82static int atlas7_wdt_disable(struct watchdog_device *wdd)
 83{
 84	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
 85
 86	writel(0, wdt->base + ATLAS7_WDT_EN);
 87	writel(readl(wdt->base + ATLAS7_WDT_CNT_CTRL) & ~ATLAS7_WDT_CNT_EN,
 88	      wdt->base + ATLAS7_WDT_CNT_CTRL);
 89
 90	return 0;
 91}
 92
 93static int atlas7_wdt_settimeout(struct watchdog_device *wdd, unsigned int to)
 94{
 95	wdd->timeout = to;
 96
 97	return 0;
 98}
 99
100#define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
101
102static const struct watchdog_info atlas7_wdt_ident = {
103	.options = OPTIONS,
104	.firmware_version = 0,
105	.identity = "atlas7 Watchdog",
106};
107
108static const struct watchdog_ops atlas7_wdt_ops = {
109	.owner = THIS_MODULE,
110	.start = atlas7_wdt_enable,
111	.stop = atlas7_wdt_disable,
112	.get_timeleft = atlas7_wdt_gettimeleft,
113	.ping = atlas7_wdt_ping,
114	.set_timeout = atlas7_wdt_settimeout,
115};
116
117static struct watchdog_device atlas7_wdd = {
118	.info = &atlas7_wdt_ident,
119	.ops = &atlas7_wdt_ops,
120	.timeout = ATLAS7_WDT_DEFAULT_TIMEOUT,
121};
122
123static const struct of_device_id atlas7_wdt_ids[] = {
124	{ .compatible = "sirf,atlas7-tick"},
125	{}
126};
127
128static int atlas7_wdt_probe(struct platform_device *pdev)
129{
130	struct device_node *np = pdev->dev.of_node;
131	struct atlas7_wdog *wdt;
132	struct resource *res;
133	struct clk *clk;
134	int ret;
135
136	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
137	if (!wdt)
138		return -ENOMEM;
139	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
140	wdt->base = devm_ioremap_resource(&pdev->dev, res);
141	if (IS_ERR(wdt->base))
142		return PTR_ERR(wdt->base);
143
144	clk = of_clk_get(np, 0);
145	if (IS_ERR(clk))
146		return PTR_ERR(clk);
147	ret = clk_prepare_enable(clk);
148	if (ret) {
149		dev_err(&pdev->dev, "clk enable failed\n");
150		goto err;
151	}
152
153	/* disable watchdog hardware */
154	writel(0, wdt->base + ATLAS7_WDT_CNT_CTRL);
155
156	wdt->tick_rate = clk_get_rate(clk);
157	if (!wdt->tick_rate) {
158		ret = -EINVAL;
159		goto err1;
160	}
161
162	wdt->clk = clk;
163	atlas7_wdd.min_timeout = 1;
164	atlas7_wdd.max_timeout = UINT_MAX / wdt->tick_rate;
165
166	watchdog_init_timeout(&atlas7_wdd, 0, &pdev->dev);
167	watchdog_set_nowayout(&atlas7_wdd, nowayout);
168
169	watchdog_set_drvdata(&atlas7_wdd, wdt);
170	platform_set_drvdata(pdev, &atlas7_wdd);
171
172	ret = watchdog_register_device(&atlas7_wdd);
173	if (ret)
174		goto err1;
175
176	return 0;
177
178err1:
179	clk_disable_unprepare(clk);
180err:
181	clk_put(clk);
182	return ret;
183}
184
185static void atlas7_wdt_shutdown(struct platform_device *pdev)
186{
187	struct watchdog_device *wdd = platform_get_drvdata(pdev);
188	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
189
190	atlas7_wdt_disable(wdd);
191	clk_disable_unprepare(wdt->clk);
192}
193
194static int atlas7_wdt_remove(struct platform_device *pdev)
195{
196	struct watchdog_device *wdd = platform_get_drvdata(pdev);
197	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
198
199	atlas7_wdt_shutdown(pdev);
200	clk_put(wdt->clk);
201	return 0;
202}
203
204static int __maybe_unused atlas7_wdt_suspend(struct device *dev)
205{
206	/*
207	 * NOTE:timer controller registers settings are saved
208	 * and restored back by the timer-atlas7.c
209	 */
210	return 0;
211}
212
213static int __maybe_unused atlas7_wdt_resume(struct device *dev)
214{
215	struct watchdog_device *wdd = dev_get_drvdata(dev);
216
217	/*
218	 * NOTE: Since timer controller registers settings are saved
219	 * and restored back by the timer-atlas7.c, so we need not
220	 * update WD settings except refreshing timeout.
221	 */
222	atlas7_wdt_ping(wdd);
223
224	return 0;
225}
226
227static SIMPLE_DEV_PM_OPS(atlas7_wdt_pm_ops,
228		atlas7_wdt_suspend, atlas7_wdt_resume);
229
230MODULE_DEVICE_TABLE(of, atlas7_wdt_ids);
231
232static struct platform_driver atlas7_wdt_driver = {
233	.driver = {
234		.name = "atlas7-wdt",
235		.pm = &atlas7_wdt_pm_ops,
236		.of_match_table	= atlas7_wdt_ids,
237	},
238	.probe = atlas7_wdt_probe,
239	.remove = atlas7_wdt_remove,
240	.shutdown = atlas7_wdt_shutdown,
241};
242module_platform_driver(atlas7_wdt_driver);
243
244MODULE_DESCRIPTION("CSRatlas7 watchdog driver");
245MODULE_AUTHOR("Guo Zeng <Guo.Zeng@csr.com>");
246MODULE_LICENSE("GPL v2");
247MODULE_ALIAS("platform:atlas7-wdt");