1// SPDX-License-Identifier: GPL-2.0+
  2/*
  3 *  Copyright (C) 2015 Mans Rullgard <mans@mansr.com>
  4 *  SMP86xx/SMP87xx Watchdog driver
  5 */
  6
  7#include <linux/bitops.h>
  8#include <linux/clk.h>
  9#include <linux/delay.h>
 10#include <linux/io.h>
 11#include <linux/kernel.h>
 12#include <linux/module.h>
 13#include <linux/moduleparam.h>
 14#include <linux/platform_device.h>
 15#include <linux/watchdog.h>
 16
 17#define DEFAULT_TIMEOUT 30
 18
 19static bool nowayout = WATCHDOG_NOWAYOUT;
 20module_param(nowayout, bool, 0);
 21MODULE_PARM_DESC(nowayout,
 22		 "Watchdog cannot be stopped once started (default="
 23		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 24
 25static unsigned int timeout;
 26module_param(timeout, int, 0);
 27MODULE_PARM_DESC(timeout, "Watchdog timeout");
 28
 29/*
 30 * Counter counts down from programmed value.  Reset asserts when
 31 * the counter reaches 1.
 32 */
 33#define WD_COUNTER		0
 34
 35#define WD_CONFIG		4
 36#define WD_CONFIG_XTAL_IN	BIT(0)
 37#define WD_CONFIG_DISABLE	BIT(31)
 38
 39struct tangox_wdt_device {
 40	struct watchdog_device wdt;
 41	void __iomem *base;
 42	unsigned long clk_rate;
 43	struct clk *clk;
 44};
 45
 46static int tangox_wdt_set_timeout(struct watchdog_device *wdt,
 47				  unsigned int new_timeout)
 48{
 49	wdt->timeout = new_timeout;
 50
 51	return 0;
 52}
 53
 54static int tangox_wdt_start(struct watchdog_device *wdt)
 55{
 56	struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
 57	u32 ticks;
 58
 59	ticks = 1 + wdt->timeout * dev->clk_rate;
 60	writel(ticks, dev->base + WD_COUNTER);
 61
 62	return 0;
 63}
 64
 65static int tangox_wdt_stop(struct watchdog_device *wdt)
 66{
 67	struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
 68
 69	writel(0, dev->base + WD_COUNTER);
 70
 71	return 0;
 72}
 73
 74static unsigned int tangox_wdt_get_timeleft(struct watchdog_device *wdt)
 75{
 76	struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
 77	u32 count;
 78
 79	count = readl(dev->base + WD_COUNTER);
 80
 81	if (!count)
 82		return 0;
 83
 84	return (count - 1) / dev->clk_rate;
 85}
 86
 87static const struct watchdog_info tangox_wdt_info = {
 88	.options  = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 89	.identity = "tangox watchdog",
 90};
 91
 92static int tangox_wdt_restart(struct watchdog_device *wdt,
 93			      unsigned long action, void *data)
 94{
 95	struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
 96
 97	writel(1, dev->base + WD_COUNTER);
 98
 99	return 0;
100}
101
102static const struct watchdog_ops tangox_wdt_ops = {
103	.start		= tangox_wdt_start,
104	.stop		= tangox_wdt_stop,
105	.set_timeout	= tangox_wdt_set_timeout,
106	.get_timeleft	= tangox_wdt_get_timeleft,
107	.restart	= tangox_wdt_restart,
108};
109
110static int tangox_wdt_probe(struct platform_device *pdev)
111{
112	struct tangox_wdt_device *dev;
113	struct resource *res;
114	u32 config;
115	int err;
116
117	dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
118	if (!dev)
119		return -ENOMEM;
120
121	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
122	dev->base = devm_ioremap_resource(&pdev->dev, res);
123	if (IS_ERR(dev->base))
124		return PTR_ERR(dev->base);
125
126	dev->clk = devm_clk_get(&pdev->dev, NULL);
127	if (IS_ERR(dev->clk))
128		return PTR_ERR(dev->clk);
129
130	err = clk_prepare_enable(dev->clk);
131	if (err)
132		return err;
133
134	dev->clk_rate = clk_get_rate(dev->clk);
135	if (!dev->clk_rate) {
136		err = -EINVAL;
137		goto err;
138	}
139
140	dev->wdt.parent = &pdev->dev;
141	dev->wdt.info = &tangox_wdt_info;
142	dev->wdt.ops = &tangox_wdt_ops;
143	dev->wdt.timeout = DEFAULT_TIMEOUT;
144	dev->wdt.min_timeout = 1;
145	dev->wdt.max_hw_heartbeat_ms = (U32_MAX - 1) / dev->clk_rate;
146
147	watchdog_init_timeout(&dev->wdt, timeout, &pdev->dev);
148	watchdog_set_nowayout(&dev->wdt, nowayout);
149	watchdog_set_drvdata(&dev->wdt, dev);
150
151	/*
152	 * Deactivate counter if disable bit is set to avoid
153	 * accidental reset.
154	 */
155	config = readl(dev->base + WD_CONFIG);
156	if (config & WD_CONFIG_DISABLE)
157		writel(0, dev->base + WD_COUNTER);
158
159	writel(WD_CONFIG_XTAL_IN, dev->base + WD_CONFIG);
160
161	/*
162	 * Mark as active and restart with configured timeout if
163	 * already running.
164	 */
165	if (readl(dev->base + WD_COUNTER)) {
166		set_bit(WDOG_HW_RUNNING, &dev->wdt.status);
167		tangox_wdt_start(&dev->wdt);
168	}
169
170	watchdog_set_restart_priority(&dev->wdt, 128);
171
172	err = watchdog_register_device(&dev->wdt);
173	if (err)
174		goto err;
175
176	platform_set_drvdata(pdev, dev);
177
178	dev_info(&pdev->dev, "SMP86xx/SMP87xx watchdog registered\n");
179
180	return 0;
181
182 err:
183	clk_disable_unprepare(dev->clk);
184	return err;
185}
186
187static int tangox_wdt_remove(struct platform_device *pdev)
188{
189	struct tangox_wdt_device *dev = platform_get_drvdata(pdev);
190
191	tangox_wdt_stop(&dev->wdt);
192	clk_disable_unprepare(dev->clk);
193
194	watchdog_unregister_device(&dev->wdt);
195
196	return 0;
197}
198
199static const struct of_device_id tangox_wdt_dt_ids[] = {
200	{ .compatible = "sigma,smp8642-wdt" },
201	{ .compatible = "sigma,smp8759-wdt" },
202	{ }
203};
204MODULE_DEVICE_TABLE(of, tangox_wdt_dt_ids);
205
206static struct platform_driver tangox_wdt_driver = {
207	.probe	= tangox_wdt_probe,
208	.remove	= tangox_wdt_remove,
209	.driver	= {
210		.name		= "tangox-wdt",
211		.of_match_table	= tangox_wdt_dt_ids,
212	},
213};
214
215module_platform_driver(tangox_wdt_driver);
216
217MODULE_AUTHOR("Mans Rullgard <mans@mansr.com>");
218MODULE_DESCRIPTION("SMP86xx/SMP87xx Watchdog driver");
219MODULE_LICENSE("GPL");