1/*
  2 * Watchdog driver for Ricoh RN5T618 PMIC
  3 *
  4 * Copyright (C) 2014 Beniamino Galvani <b.galvani@gmail.com>
  5 *
  6 * This program is free software; you can redistribute it and/or
  7 * modify it under the terms of the GNU General Public License
  8 * version 2 as published by the Free Software Foundation.
  9 *
 10 * You should have received a copy of the GNU General Public License
 11 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 12 */
 13
 14#include <linux/device.h>
 15#include <linux/mfd/rn5t618.h>
 16#include <linux/module.h>
 17#include <linux/platform_device.h>
 18#include <linux/watchdog.h>
 19
 20#define DRIVER_NAME "rn5t618-wdt"
 21
 22static bool nowayout = WATCHDOG_NOWAYOUT;
 23static unsigned int timeout;
 24
 25module_param(timeout, uint, 0);
 26MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds");
 27
 28module_param(nowayout, bool, 0);
 29MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 30		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 31
 32struct rn5t618_wdt {
 33	struct watchdog_device wdt_dev;
 34	struct rn5t618 *rn5t618;
 35};
 36
 37/*
 38 * This array encodes the values of WDOGTIM field for the supported
 39 * watchdog expiration times. If the watchdog is not accessed before
 40 * the timer expiration, the PMU generates an interrupt and if the CPU
 41 * doesn't clear it within one second the system is restarted.
 42 */
 43static const struct {
 44	u8 reg_val;
 45	unsigned int time;
 46} rn5t618_wdt_map[] = {
 47	{ 0, 1 },
 48	{ 1, 8 },
 49	{ 2, 32 },
 50	{ 3, 128 },
 51};
 52
 53static int rn5t618_wdt_set_timeout(struct watchdog_device *wdt_dev,
 54				   unsigned int t)
 55{
 56	struct rn5t618_wdt *wdt = watchdog_get_drvdata(wdt_dev);
 57	int ret, i;
 58
 59	for (i = 0; i < ARRAY_SIZE(rn5t618_wdt_map); i++) {
 60		if (rn5t618_wdt_map[i].time + 1 >= t)
 61			break;
 62	}
 63
 64	if (i == ARRAY_SIZE(rn5t618_wdt_map))
 65		return -EINVAL;
 66
 67	ret = regmap_update_bits(wdt->rn5t618->regmap, RN5T618_WATCHDOG,
 68				 RN5T618_WATCHDOG_WDOGTIM_M,
 69				 rn5t618_wdt_map[i].reg_val);
 70	if (!ret)
 71		wdt_dev->timeout = rn5t618_wdt_map[i].time;
 72
 73	return ret;
 74}
 75
 76static int rn5t618_wdt_start(struct watchdog_device *wdt_dev)
 77{
 78	struct rn5t618_wdt *wdt = watchdog_get_drvdata(wdt_dev);
 79	int ret;
 80
 81	ret = rn5t618_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
 82	if (ret)
 83		return ret;
 84
 85	/* enable repower-on */
 86	ret = regmap_update_bits(wdt->rn5t618->regmap, RN5T618_REPCNT,
 87				 RN5T618_REPCNT_REPWRON,
 88				 RN5T618_REPCNT_REPWRON);
 89	if (ret)
 90		return ret;
 91
 92	/* enable watchdog */
 93	ret = regmap_update_bits(wdt->rn5t618->regmap, RN5T618_WATCHDOG,
 94				 RN5T618_WATCHDOG_WDOGEN,
 95				 RN5T618_WATCHDOG_WDOGEN);
 96	if (ret)
 97		return ret;
 98
 99	/* enable watchdog interrupt */
100	return regmap_update_bits(wdt->rn5t618->regmap, RN5T618_PWRIREN,
101				  RN5T618_PWRIRQ_IR_WDOG,
102				  RN5T618_PWRIRQ_IR_WDOG);
103}
104
105static int rn5t618_wdt_stop(struct watchdog_device *wdt_dev)
106{
107	struct rn5t618_wdt *wdt = watchdog_get_drvdata(wdt_dev);
108
109	return regmap_update_bits(wdt->rn5t618->regmap, RN5T618_WATCHDOG,
110				  RN5T618_WATCHDOG_WDOGEN, 0);
111}
112
113static int rn5t618_wdt_ping(struct watchdog_device *wdt_dev)
114{
115	struct rn5t618_wdt *wdt = watchdog_get_drvdata(wdt_dev);
116	unsigned int val;
117	int ret;
118
119	/* The counter is restarted after a R/W access to watchdog register */
120	ret = regmap_read(wdt->rn5t618->regmap, RN5T618_WATCHDOG, &val);
121	if (ret)
122		return ret;
123
124	ret = regmap_write(wdt->rn5t618->regmap, RN5T618_WATCHDOG, val);
125	if (ret)
126		return ret;
127
128	/* Clear pending watchdog interrupt */
129	return regmap_update_bits(wdt->rn5t618->regmap, RN5T618_PWRIRQ,
130				  RN5T618_PWRIRQ_IR_WDOG, 0);
131}
132
133static struct watchdog_info rn5t618_wdt_info = {
134	.options	= WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
135			  WDIOF_KEEPALIVEPING,
136	.identity	= DRIVER_NAME,
137};
138
139static const struct watchdog_ops rn5t618_wdt_ops = {
140	.owner          = THIS_MODULE,
141	.start          = rn5t618_wdt_start,
142	.stop           = rn5t618_wdt_stop,
143	.ping           = rn5t618_wdt_ping,
144	.set_timeout    = rn5t618_wdt_set_timeout,
145};
146
147static int rn5t618_wdt_probe(struct platform_device *pdev)
148{
149	struct rn5t618 *rn5t618 = dev_get_drvdata(pdev->dev.parent);
150	struct rn5t618_wdt *wdt;
151	int min_timeout, max_timeout;
152
153	wdt = devm_kzalloc(&pdev->dev, sizeof(struct rn5t618_wdt), GFP_KERNEL);
154	if (!wdt)
155		return -ENOMEM;
156
157	min_timeout = rn5t618_wdt_map[0].time;
158	max_timeout = rn5t618_wdt_map[ARRAY_SIZE(rn5t618_wdt_map) - 1].time;
159
160	wdt->rn5t618 = rn5t618;
161	wdt->wdt_dev.info = &rn5t618_wdt_info;
162	wdt->wdt_dev.ops = &rn5t618_wdt_ops;
163	wdt->wdt_dev.min_timeout = min_timeout;
164	wdt->wdt_dev.max_timeout = max_timeout;
165	wdt->wdt_dev.timeout = max_timeout;
166	wdt->wdt_dev.parent = &pdev->dev;
167
168	watchdog_set_drvdata(&wdt->wdt_dev, wdt);
169	watchdog_init_timeout(&wdt->wdt_dev, timeout, &pdev->dev);
170	watchdog_set_nowayout(&wdt->wdt_dev, nowayout);
171
172	platform_set_drvdata(pdev, wdt);
173
174	return watchdog_register_device(&wdt->wdt_dev);
175}
176
177static int rn5t618_wdt_remove(struct platform_device *pdev)
178{
179	struct rn5t618_wdt *wdt = platform_get_drvdata(pdev);
180
181	watchdog_unregister_device(&wdt->wdt_dev);
182
183	return 0;
184}
185
186static struct platform_driver rn5t618_wdt_driver = {
187	.probe = rn5t618_wdt_probe,
188	.remove = rn5t618_wdt_remove,
189	.driver = {
190		.name	= DRIVER_NAME,
191	},
192};
193
194module_platform_driver(rn5t618_wdt_driver);
195
196MODULE_AUTHOR("Beniamino Galvani <b.galvani@gmail.com>");
197MODULE_DESCRIPTION("RN5T618 watchdog driver");
198MODULE_LICENSE("GPL v2");