1/*
  2 * System monitoring driver for DA9055 PMICs.
  3 *
  4 * Copyright(c) 2012 Dialog Semiconductor Ltd.
  5 *
  6 * Author: David Dajun Chen <dchen@diasemi.com>
  7 *
  8 * This program is free software; you can redistribute it and/or modify
  9 * it under the terms of the GNU General Public License as published by
 10 * the Free Software Foundation; either version 2 of the License, or
 11 * (at your option) any later version.
 12 *
 13 */
 14
 15#include <linux/module.h>
 16#include <linux/types.h>
 17#include <linux/kernel.h>
 18#include <linux/slab.h>
 19#include <linux/platform_device.h>
 20#include <linux/watchdog.h>
 21#include <linux/delay.h>
 22
 23#include <linux/mfd/da9055/core.h>
 24#include <linux/mfd/da9055/reg.h>
 25
 26static bool nowayout = WATCHDOG_NOWAYOUT;
 27module_param(nowayout, bool, 0);
 28MODULE_PARM_DESC(nowayout,
 29		 "Watchdog cannot be stopped once started (default="
 30		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 31
 32#define DA9055_DEF_TIMEOUT	4
 33#define DA9055_TWDMIN		256
 34
 35struct da9055_wdt_data {
 36	struct watchdog_device wdt;
 37	struct da9055 *da9055;
 38};
 39
 40static const struct {
 41	u8 reg_val;
 42	int user_time;  /* In seconds */
 43} da9055_wdt_maps[] = {
 44	{ 0, 0 },
 45	{ 1, 2 },
 46	{ 2, 4 },
 47	{ 3, 8 },
 48	{ 4, 16 },
 49	{ 5, 32 },
 50	{ 5, 33 },  /* Actual time  32.768s so included both 32s and 33s */
 51	{ 6, 65 },
 52	{ 6, 66 },  /* Actual time 65.536s so include both, 65s and 66s */
 53	{ 7, 131 },
 54};
 55
 56static int da9055_wdt_set_timeout(struct watchdog_device *wdt_dev,
 57				  unsigned int timeout)
 58{
 59	struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
 60	struct da9055 *da9055 = driver_data->da9055;
 61	int ret, i;
 62
 63	for (i = 0; i < ARRAY_SIZE(da9055_wdt_maps); i++)
 64		if (da9055_wdt_maps[i].user_time == timeout)
 65			break;
 66
 67	if (i == ARRAY_SIZE(da9055_wdt_maps))
 68		ret = -EINVAL;
 69	else
 70		ret = da9055_reg_update(da9055, DA9055_REG_CONTROL_B,
 71					DA9055_TWDSCALE_MASK,
 72					da9055_wdt_maps[i].reg_val <<
 73					DA9055_TWDSCALE_SHIFT);
 74	if (ret < 0) {
 75		dev_err(da9055->dev,
 76			"Failed to update timescale bit, %d\n", ret);
 77		return ret;
 78	}
 79
 80	wdt_dev->timeout = timeout;
 81
 82	return 0;
 83}
 84
 85static int da9055_wdt_ping(struct watchdog_device *wdt_dev)
 86{
 87	struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
 88	struct da9055 *da9055 = driver_data->da9055;
 89
 90	/*
 91	 * We have a minimum time for watchdog window called TWDMIN. A write
 92	 * to the watchdog before this elapsed time will cause an error.
 93	 */
 94	mdelay(DA9055_TWDMIN);
 95
 96	/* Reset the watchdog timer */
 97	return da9055_reg_update(da9055, DA9055_REG_CONTROL_E,
 98				 DA9055_WATCHDOG_MASK, 1);
 99}
100
101static int da9055_wdt_start(struct watchdog_device *wdt_dev)
102{
103	return da9055_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
104}
105
106static int da9055_wdt_stop(struct watchdog_device *wdt_dev)
107{
108	return da9055_wdt_set_timeout(wdt_dev, 0);
109}
110
111static struct watchdog_info da9055_wdt_info = {
112	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
113	.identity	= "DA9055 Watchdog",
114};
115
116static const struct watchdog_ops da9055_wdt_ops = {
117	.owner = THIS_MODULE,
118	.start = da9055_wdt_start,
119	.stop = da9055_wdt_stop,
120	.ping = da9055_wdt_ping,
121	.set_timeout = da9055_wdt_set_timeout,
122};
123
124static int da9055_wdt_probe(struct platform_device *pdev)
125{
126	struct da9055 *da9055 = dev_get_drvdata(pdev->dev.parent);
127	struct da9055_wdt_data *driver_data;
128	struct watchdog_device *da9055_wdt;
129	int ret;
130
131	driver_data = devm_kzalloc(&pdev->dev, sizeof(*driver_data),
132				   GFP_KERNEL);
133	if (!driver_data)
134		return -ENOMEM;
135
136	driver_data->da9055 = da9055;
137
138	da9055_wdt = &driver_data->wdt;
139
140	da9055_wdt->timeout = DA9055_DEF_TIMEOUT;
141	da9055_wdt->info = &da9055_wdt_info;
142	da9055_wdt->ops = &da9055_wdt_ops;
143	da9055_wdt->parent = &pdev->dev;
144	watchdog_set_nowayout(da9055_wdt, nowayout);
145	watchdog_set_drvdata(da9055_wdt, driver_data);
146
147	ret = da9055_wdt_stop(da9055_wdt);
148	if (ret < 0) {
149		dev_err(&pdev->dev, "Failed to stop watchdog, %d\n", ret);
150		goto err;
151	}
152
153	platform_set_drvdata(pdev, driver_data);
154
155	ret = watchdog_register_device(&driver_data->wdt);
156	if (ret != 0)
157		dev_err(da9055->dev, "watchdog_register_device() failed: %d\n",
158			ret);
159
160err:
161	return ret;
162}
163
164static int da9055_wdt_remove(struct platform_device *pdev)
165{
166	struct da9055_wdt_data *driver_data = platform_get_drvdata(pdev);
167
168	watchdog_unregister_device(&driver_data->wdt);
169
170	return 0;
171}
172
173static struct platform_driver da9055_wdt_driver = {
174	.probe = da9055_wdt_probe,
175	.remove = da9055_wdt_remove,
176	.driver = {
177		.name	= "da9055-watchdog",
178	},
179};
180
181module_platform_driver(da9055_wdt_driver);
182
183MODULE_AUTHOR("David Dajun Chen <dchen@diasemi.com>");
184MODULE_DESCRIPTION("DA9055 watchdog");
185MODULE_LICENSE("GPL");
186MODULE_ALIAS("platform:da9055-watchdog");