1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Watchdog driver for TS-4800 based boards
  4 *
  5 * Copyright (c) 2015 - Savoir-faire Linux
  6 *
  7 */
  8
  9#include <linux/kernel.h>
 10#include <linux/mfd/syscon.h>
 11#include <linux/module.h>
 12#include <linux/of.h>
 13#include <linux/platform_device.h>
 14#include <linux/regmap.h>
 15#include <linux/watchdog.h>
 16
 17static bool nowayout = WATCHDOG_NOWAYOUT;
 18module_param(nowayout, bool, 0);
 19MODULE_PARM_DESC(nowayout,
 20	"Watchdog cannot be stopped once started (default="
 21	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 22
 23/* possible feed values */
 24#define TS4800_WDT_FEED_2S       0x1
 25#define TS4800_WDT_FEED_10S      0x2
 26#define TS4800_WDT_DISABLE       0x3
 27
 28struct ts4800_wdt {
 29	struct watchdog_device  wdd;
 30	struct regmap           *regmap;
 31	u32                     feed_offset;
 32	u32                     feed_val;
 33};
 34
 35/*
 36 * TS-4800 supports the following timeout values:
 37 *
 38 *   value desc
 39 *   ---------------------
 40 *     0    feed for 338ms
 41 *     1    feed for 2.706s
 42 *     2    feed for 10.824s
 43 *     3    disable watchdog
 44 *
 45 * Keep the regmap/timeout map ordered by timeout
 46 */
 47static const struct {
 48	const int timeout;
 49	const int regval;
 50} ts4800_wdt_map[] = {
 51	{ 2,  TS4800_WDT_FEED_2S },
 52	{ 10, TS4800_WDT_FEED_10S },
 53};
 54
 55#define MAX_TIMEOUT_INDEX       (ARRAY_SIZE(ts4800_wdt_map) - 1)
 56
 57static void ts4800_write_feed(struct ts4800_wdt *wdt, u32 val)
 58{
 59	regmap_write(wdt->regmap, wdt->feed_offset, val);
 60}
 61
 62static int ts4800_wdt_start(struct watchdog_device *wdd)
 63{
 64	struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
 65
 66	ts4800_write_feed(wdt, wdt->feed_val);
 67	return 0;
 68}
 69
 70static int ts4800_wdt_stop(struct watchdog_device *wdd)
 71{
 72	struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
 73
 74	ts4800_write_feed(wdt, TS4800_WDT_DISABLE);
 75	return 0;
 76}
 77
 78static int ts4800_wdt_set_timeout(struct watchdog_device *wdd,
 79				  unsigned int timeout)
 80{
 81	struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
 82	int i;
 83
 84	for (i = 0; i < MAX_TIMEOUT_INDEX; i++) {
 85		if (ts4800_wdt_map[i].timeout >= timeout)
 86			break;
 87	}
 88
 89	wdd->timeout = ts4800_wdt_map[i].timeout;
 90	wdt->feed_val = ts4800_wdt_map[i].regval;
 91
 92	return 0;
 93}
 94
 95static const struct watchdog_ops ts4800_wdt_ops = {
 96	.owner = THIS_MODULE,
 97	.start = ts4800_wdt_start,
 98	.stop = ts4800_wdt_stop,
 99	.set_timeout = ts4800_wdt_set_timeout,
100};
101
102static const struct watchdog_info ts4800_wdt_info = {
103	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
104	.identity = "TS-4800 Watchdog",
105};
106
107static int ts4800_wdt_probe(struct platform_device *pdev)
108{
109	struct device *dev = &pdev->dev;
110	struct device_node *np = dev->of_node;
111	struct device_node *syscon_np;
112	struct watchdog_device *wdd;
113	struct ts4800_wdt *wdt;
114	u32 reg;
115	int ret;
116
117	syscon_np = of_parse_phandle(np, "syscon", 0);
118	if (!syscon_np) {
119		dev_err(dev, "no syscon property\n");
120		return -ENODEV;
121	}
122
123	ret = of_property_read_u32_index(np, "syscon", 1, &reg);
124	if (ret < 0) {
125		dev_err(dev, "no offset in syscon\n");
126		of_node_put(syscon_np);
127		return ret;
128	}
129
130	/* allocate memory for watchdog struct */
131	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
132	if (!wdt) {
133		of_node_put(syscon_np);
134		return -ENOMEM;
135	}
136
137	/* set regmap and offset to know where to write */
138	wdt->feed_offset = reg;
139	wdt->regmap = syscon_node_to_regmap(syscon_np);
140	of_node_put(syscon_np);
141	if (IS_ERR(wdt->regmap)) {
142		dev_err(dev, "cannot get parent's regmap\n");
143		return PTR_ERR(wdt->regmap);
144	}
145
146	/* Initialize struct watchdog_device */
147	wdd = &wdt->wdd;
148	wdd->parent = dev;
149	wdd->info = &ts4800_wdt_info;
150	wdd->ops = &ts4800_wdt_ops;
151	wdd->min_timeout = ts4800_wdt_map[0].timeout;
152	wdd->max_timeout = ts4800_wdt_map[MAX_TIMEOUT_INDEX].timeout;
153
154	watchdog_set_drvdata(wdd, wdt);
155	watchdog_set_nowayout(wdd, nowayout);
156	watchdog_init_timeout(wdd, 0, dev);
157
158	/*
159	 * As this watchdog supports only a few values, ts4800_wdt_set_timeout
160	 * must be called to initialize timeout and feed_val with valid values.
161	 * Default to maximum timeout if none, or an invalid one, is provided in
162	 * device tree.
163	 */
164	if (!wdd->timeout)
165		wdd->timeout = wdd->max_timeout;
166	ts4800_wdt_set_timeout(wdd, wdd->timeout);
167
168	/*
169	 * The feed register is write-only, so it is not possible to determine
170	 * watchdog's state. Disable it to be in a known state.
171	 */
172	ts4800_wdt_stop(wdd);
173
174	ret = devm_watchdog_register_device(dev, wdd);
175	if (ret)
176		return ret;
177
178	platform_set_drvdata(pdev, wdt);
179
180	dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n",
181		 wdd->timeout, nowayout);
182
183	return 0;
184}
185
186static const struct of_device_id ts4800_wdt_of_match[] = {
187	{ .compatible = "technologic,ts4800-wdt", },
188	{ },
189};
190MODULE_DEVICE_TABLE(of, ts4800_wdt_of_match);
191
192static struct platform_driver ts4800_wdt_driver = {
193	.probe		= ts4800_wdt_probe,
194	.driver		= {
195		.name	= "ts4800_wdt",
196		.of_match_table = ts4800_wdt_of_match,
197	},
198};
199
200module_platform_driver(ts4800_wdt_driver);
201
202MODULE_AUTHOR("Damien Riegel <damien.riegel@savoirfairelinux.com>");
203MODULE_LICENSE("GPL v2");
204MODULE_ALIAS("platform:ts4800_wdt");