1/*
  2 * da9062_wdt.c - WDT device driver for DA9062
  3 * Copyright (C) 2015  Dialog Semiconductor Ltd.
  4 *
  5 * This program is free software; you can redistribute it and/or
  6 * modify it under the terms of the GNU General Public License
  7 * as published by the Free Software Foundation; either version 2
  8 * of the License, or (at your option) any later version.
  9 *
 10 * This program is distributed in the hope that it will be useful,
 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 13 * GNU General Public License for more details.
 14 */
 15
 16#include <linux/kernel.h>
 17#include <linux/module.h>
 18#include <linux/watchdog.h>
 19#include <linux/platform_device.h>
 20#include <linux/uaccess.h>
 21#include <linux/slab.h>
 22#include <linux/delay.h>
 23#include <linux/jiffies.h>
 24#include <linux/mfd/da9062/registers.h>
 25#include <linux/mfd/da9062/core.h>
 26#include <linux/regmap.h>
 27#include <linux/of.h>
 28
 29static const unsigned int wdt_timeout[] = { 0, 2, 4, 8, 16, 32, 65, 131 };
 30#define DA9062_TWDSCALE_DISABLE		0
 31#define DA9062_TWDSCALE_MIN		1
 32#define DA9062_TWDSCALE_MAX		(ARRAY_SIZE(wdt_timeout) - 1)
 33#define DA9062_WDT_MIN_TIMEOUT		wdt_timeout[DA9062_TWDSCALE_MIN]
 34#define DA9062_WDT_MAX_TIMEOUT		wdt_timeout[DA9062_TWDSCALE_MAX]
 35#define DA9062_WDG_DEFAULT_TIMEOUT	wdt_timeout[DA9062_TWDSCALE_MAX-1]
 36#define DA9062_RESET_PROTECTION_MS	300
 37
 38struct da9062_watchdog {
 39	struct da9062 *hw;
 40	struct watchdog_device wdtdev;
 41	unsigned long j_time_stamp;
 42};
 43
 44static void da9062_set_window_start(struct da9062_watchdog *wdt)
 45{
 46	wdt->j_time_stamp = jiffies;
 47}
 48
 49static void da9062_apply_window_protection(struct da9062_watchdog *wdt)
 50{
 51	unsigned long delay = msecs_to_jiffies(DA9062_RESET_PROTECTION_MS);
 52	unsigned long timeout = wdt->j_time_stamp + delay;
 53	unsigned long now = jiffies;
 54	unsigned int diff_ms;
 55
 56	/* if time-limit has not elapsed then wait for remainder */
 57	if (time_before(now, timeout)) {
 58		diff_ms = jiffies_to_msecs(timeout-now);
 59		dev_dbg(wdt->hw->dev,
 60			"Kicked too quickly. Delaying %u msecs\n", diff_ms);
 61		msleep(diff_ms);
 62	}
 63}
 64
 65static unsigned int da9062_wdt_timeout_to_sel(unsigned int secs)
 66{
 67	unsigned int i;
 68
 69	for (i = DA9062_TWDSCALE_MIN; i <= DA9062_TWDSCALE_MAX; i++) {
 70		if (wdt_timeout[i] >= secs)
 71			return i;
 72	}
 73
 74	return DA9062_TWDSCALE_MAX;
 75}
 76
 77static int da9062_reset_watchdog_timer(struct da9062_watchdog *wdt)
 78{
 79	int ret;
 80
 81	da9062_apply_window_protection(wdt);
 82
 83	ret = regmap_update_bits(wdt->hw->regmap,
 84			   DA9062AA_CONTROL_F,
 85			   DA9062AA_WATCHDOG_MASK,
 86			   DA9062AA_WATCHDOG_MASK);
 87
 88	da9062_set_window_start(wdt);
 89
 90	return ret;
 91}
 92
 93static int da9062_wdt_update_timeout_register(struct da9062_watchdog *wdt,
 94					      unsigned int regval)
 95{
 96	struct da9062 *chip = wdt->hw;
 97	int ret;
 98
 99	ret = da9062_reset_watchdog_timer(wdt);
100	if (ret)
101		return ret;
102
103	return regmap_update_bits(chip->regmap,
104				  DA9062AA_CONTROL_D,
105				  DA9062AA_TWDSCALE_MASK,
106				  regval);
107}
108
109static int da9062_wdt_start(struct watchdog_device *wdd)
110{
111	struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
112	unsigned int selector;
113	int ret;
114
115	selector = da9062_wdt_timeout_to_sel(wdt->wdtdev.timeout);
116	ret = da9062_wdt_update_timeout_register(wdt, selector);
117	if (ret)
118		dev_err(wdt->hw->dev, "Watchdog failed to start (err = %d)\n",
119			ret);
120
121	return ret;
122}
123
124static int da9062_wdt_stop(struct watchdog_device *wdd)
125{
126	struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
127	int ret;
128
129	ret = da9062_reset_watchdog_timer(wdt);
130	if (ret) {
131		dev_err(wdt->hw->dev, "Failed to ping the watchdog (err = %d)\n",
132			ret);
133		return ret;
134	}
135
136	ret = regmap_update_bits(wdt->hw->regmap,
137				 DA9062AA_CONTROL_D,
138				 DA9062AA_TWDSCALE_MASK,
139				 DA9062_TWDSCALE_DISABLE);
140	if (ret)
141		dev_err(wdt->hw->dev, "Watchdog failed to stop (err = %d)\n",
142			ret);
143
144	return ret;
145}
146
147static int da9062_wdt_ping(struct watchdog_device *wdd)
148{
149	struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
150	int ret;
151
152	ret = da9062_reset_watchdog_timer(wdt);
153	if (ret)
154		dev_err(wdt->hw->dev, "Failed to ping the watchdog (err = %d)\n",
155			ret);
156
157	return ret;
158}
159
160static int da9062_wdt_set_timeout(struct watchdog_device *wdd,
161				  unsigned int timeout)
162{
163	struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
164	unsigned int selector;
165	int ret;
166
167	selector = da9062_wdt_timeout_to_sel(timeout);
168	ret = da9062_wdt_update_timeout_register(wdt, selector);
169	if (ret)
170		dev_err(wdt->hw->dev, "Failed to set watchdog timeout (err = %d)\n",
171			ret);
172	else
173		wdd->timeout = wdt_timeout[selector];
174
175	return ret;
176}
177
178static const struct watchdog_info da9062_watchdog_info = {
179	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
180	.identity = "DA9062 WDT",
181};
182
183static const struct watchdog_ops da9062_watchdog_ops = {
184	.owner = THIS_MODULE,
185	.start = da9062_wdt_start,
186	.stop = da9062_wdt_stop,
187	.ping = da9062_wdt_ping,
188	.set_timeout = da9062_wdt_set_timeout,
189};
190
191static int da9062_wdt_probe(struct platform_device *pdev)
192{
193	int ret;
194	struct da9062 *chip;
195	struct da9062_watchdog *wdt;
196
197	chip = dev_get_drvdata(pdev->dev.parent);
198	if (!chip)
199		return -EINVAL;
200
201	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
202	if (!wdt)
203		return -ENOMEM;
204
205	wdt->hw = chip;
206
207	wdt->wdtdev.info = &da9062_watchdog_info;
208	wdt->wdtdev.ops = &da9062_watchdog_ops;
209	wdt->wdtdev.min_timeout = DA9062_WDT_MIN_TIMEOUT;
210	wdt->wdtdev.max_timeout = DA9062_WDT_MAX_TIMEOUT;
211	wdt->wdtdev.timeout = DA9062_WDG_DEFAULT_TIMEOUT;
212	wdt->wdtdev.status = WATCHDOG_NOWAYOUT_INIT_STATUS;
213	wdt->wdtdev.parent = &pdev->dev;
214
215	watchdog_set_drvdata(&wdt->wdtdev, wdt);
216	dev_set_drvdata(&pdev->dev, wdt);
217
218	ret = watchdog_register_device(&wdt->wdtdev);
219	if (ret < 0) {
220		dev_err(wdt->hw->dev,
221			"watchdog registration failed (%d)\n", ret);
222		return ret;
223	}
224
225	da9062_set_window_start(wdt);
226
227	ret = da9062_wdt_ping(&wdt->wdtdev);
228	if (ret < 0)
229		watchdog_unregister_device(&wdt->wdtdev);
230
231	return ret;
232}
233
234static int da9062_wdt_remove(struct platform_device *pdev)
235{
236	struct da9062_watchdog *wdt = dev_get_drvdata(&pdev->dev);
237
238	watchdog_unregister_device(&wdt->wdtdev);
239	return 0;
240}
241
242static struct platform_driver da9062_wdt_driver = {
243	.probe = da9062_wdt_probe,
244	.remove = da9062_wdt_remove,
245	.driver = {
246		.name = "da9062-watchdog",
247	},
248};
249module_platform_driver(da9062_wdt_driver);
250
251MODULE_AUTHOR("S Twiss <stwiss.opensource@diasemi.com>");
252MODULE_DESCRIPTION("WDT device driver for Dialog DA9062");
253MODULE_LICENSE("GPL");
254MODULE_ALIAS("platform:da9062-watchdog");