1/*
  2 *  Copyright (C) 2015 Mans Rullgard <mans@mansr.com>
  3 *  SMP86xx/SMP87xx Watchdog driver
  4 *
  5 *  This program is free software; you can redistribute it and/or modify it
  6 *  under  the terms of the GNU General  Public License as published by the
  7 *  Free Software Foundation;  either version 2 of the License, or (at your
  8 *  option) any later version.
  9 */
 10
 11#include <linux/bitops.h>
 12#include <linux/clk.h>
 13#include <linux/delay.h>
 14#include <linux/io.h>
 15#include <linux/kernel.h>
 16#include <linux/module.h>
 17#include <linux/moduleparam.h>
 18#include <linux/notifier.h>
 19#include <linux/platform_device.h>
 20#include <linux/reboot.h>
 21#include <linux/watchdog.h>
 22
 23#define DEFAULT_TIMEOUT 30
 24
 25static bool nowayout = WATCHDOG_NOWAYOUT;
 26module_param(nowayout, bool, 0);
 27MODULE_PARM_DESC(nowayout,
 28		 "Watchdog cannot be stopped once started (default="
 29		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 30
 31static unsigned int timeout;
 32module_param(timeout, int, 0);
 33MODULE_PARM_DESC(timeout, "Watchdog timeout");
 34
 35/*
 36 * Counter counts down from programmed value.  Reset asserts when
 37 * the counter reaches 1.
 38 */
 39#define WD_COUNTER		0
 40
 41#define WD_CONFIG		4
 42#define WD_CONFIG_XTAL_IN	BIT(0)
 43#define WD_CONFIG_DISABLE	BIT(31)
 44
 45struct tangox_wdt_device {
 46	struct watchdog_device wdt;
 47	void __iomem *base;
 48	unsigned long clk_rate;
 49	struct clk *clk;
 50	struct notifier_block restart;
 51};
 52
 53static int tangox_wdt_set_timeout(struct watchdog_device *wdt,
 54				  unsigned int new_timeout)
 55{
 56	wdt->timeout = new_timeout;
 57
 58	return 0;
 59}
 60
 61static int tangox_wdt_start(struct watchdog_device *wdt)
 62{
 63	struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
 64	u32 ticks;
 65
 66	ticks = 1 + wdt->timeout * dev->clk_rate;
 67	writel(ticks, dev->base + WD_COUNTER);
 68
 69	return 0;
 70}
 71
 72static int tangox_wdt_stop(struct watchdog_device *wdt)
 73{
 74	struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
 75
 76	writel(0, dev->base + WD_COUNTER);
 77
 78	return 0;
 79}
 80
 81static unsigned int tangox_wdt_get_timeleft(struct watchdog_device *wdt)
 82{
 83	struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
 84	u32 count;
 85
 86	count = readl(dev->base + WD_COUNTER);
 87
 88	if (!count)
 89		return 0;
 90
 91	return (count - 1) / dev->clk_rate;
 92}
 93
 94static const struct watchdog_info tangox_wdt_info = {
 95	.options  = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 96	.identity = "tangox watchdog",
 97};
 98
 99static const struct watchdog_ops tangox_wdt_ops = {
100	.start		= tangox_wdt_start,
101	.stop		= tangox_wdt_stop,
102	.set_timeout	= tangox_wdt_set_timeout,
103	.get_timeleft	= tangox_wdt_get_timeleft,
104};
105
106static int tangox_wdt_restart(struct notifier_block *nb, unsigned long action,
107			      void *data)
108{
109	struct tangox_wdt_device *dev =
110		container_of(nb, struct tangox_wdt_device, restart);
111
112	writel(1, dev->base + WD_COUNTER);
113
114	return NOTIFY_DONE;
115}
116
117static int tangox_wdt_probe(struct platform_device *pdev)
118{
119	struct tangox_wdt_device *dev;
120	struct resource *res;
121	u32 config;
122	int err;
123
124	dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
125	if (!dev)
126		return -ENOMEM;
127
128	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
129	dev->base = devm_ioremap_resource(&pdev->dev, res);
130	if (IS_ERR(dev->base))
131		return PTR_ERR(dev->base);
132
133	dev->clk = devm_clk_get(&pdev->dev, NULL);
134	if (IS_ERR(dev->clk))
135		return PTR_ERR(dev->clk);
136
137	err = clk_prepare_enable(dev->clk);
138	if (err)
139		return err;
140
141	dev->clk_rate = clk_get_rate(dev->clk);
142	if (!dev->clk_rate) {
143		err = -EINVAL;
144		goto err;
145	}
146
147	dev->wdt.parent = &pdev->dev;
148	dev->wdt.info = &tangox_wdt_info;
149	dev->wdt.ops = &tangox_wdt_ops;
150	dev->wdt.timeout = DEFAULT_TIMEOUT;
151	dev->wdt.min_timeout = 1;
152	dev->wdt.max_timeout = (U32_MAX - 1) / dev->clk_rate;
153
154	watchdog_init_timeout(&dev->wdt, timeout, &pdev->dev);
155	watchdog_set_nowayout(&dev->wdt, nowayout);
156	watchdog_set_drvdata(&dev->wdt, dev);
157
158	/*
159	 * Deactivate counter if disable bit is set to avoid
160	 * accidental reset.
161	 */
162	config = readl(dev->base + WD_CONFIG);
163	if (config & WD_CONFIG_DISABLE)
164		writel(0, dev->base + WD_COUNTER);
165
166	writel(WD_CONFIG_XTAL_IN, dev->base + WD_CONFIG);
167
168	/*
169	 * Mark as active and restart with configured timeout if
170	 * already running.
171	 */
172	if (readl(dev->base + WD_COUNTER)) {
173		set_bit(WDOG_ACTIVE, &dev->wdt.status);
174		tangox_wdt_start(&dev->wdt);
175	}
176
177	err = watchdog_register_device(&dev->wdt);
178	if (err)
179		goto err;
180
181	platform_set_drvdata(pdev, dev);
182
183	dev->restart.notifier_call = tangox_wdt_restart;
184	dev->restart.priority = 128;
185	err = register_restart_handler(&dev->restart);
186	if (err)
187		dev_warn(&pdev->dev, "failed to register restart handler\n");
188
189	dev_info(&pdev->dev, "SMP86xx/SMP87xx watchdog registered\n");
190
191	return 0;
192
193 err:
194	clk_disable_unprepare(dev->clk);
195	return err;
196}
197
198static int tangox_wdt_remove(struct platform_device *pdev)
199{
200	struct tangox_wdt_device *dev = platform_get_drvdata(pdev);
201
202	tangox_wdt_stop(&dev->wdt);
203	clk_disable_unprepare(dev->clk);
204
205	unregister_restart_handler(&dev->restart);
206	watchdog_unregister_device(&dev->wdt);
207
208	return 0;
209}
210
211static const struct of_device_id tangox_wdt_dt_ids[] = {
212	{ .compatible = "sigma,smp8642-wdt" },
213	{ .compatible = "sigma,smp8759-wdt" },
214	{ }
215};
216MODULE_DEVICE_TABLE(of, tangox_wdt_dt_ids);
217
218static struct platform_driver tangox_wdt_driver = {
219	.probe	= tangox_wdt_probe,
220	.remove	= tangox_wdt_remove,
221	.driver	= {
222		.name		= "tangox-wdt",
223		.of_match_table	= tangox_wdt_dt_ids,
224	},
225};
226
227module_platform_driver(tangox_wdt_driver);
228
229MODULE_AUTHOR("Mans Rullgard <mans@mansr.com>");
230MODULE_DESCRIPTION("SMP86xx/SMP87xx Watchdog driver");
231MODULE_LICENSE("GPL");