1/*
2 * drivers/char/watchdog/max63xx_wdt.c
3 *
4 * Driver for max63{69,70,71,72,73,74} watchdog timers
5 *
6 * Copyright (C) 2009 Marc Zyngier <maz@misterjones.org>
7 *
8 * This file is licensed under the terms of the GNU General Public
9 * License version 2. This program is licensed "as is" without any
10 * warranty of any kind, whether express or implied.
11 *
12 * This driver assumes the watchdog pins are memory mapped (as it is
13 * the case for the Arcom Zeus). Should it be connected over GPIOs or
14 * another interface, some abstraction will have to be introduced.
15 */
16
17#include <linux/err.h>
18#include <linux/module.h>
19#include <linux/moduleparam.h>
20#include <linux/mod_devicetable.h>
21#include <linux/types.h>
22#include <linux/kernel.h>
23#include <linux/watchdog.h>
24#include <linux/bitops.h>
25#include <linux/platform_device.h>
26#include <linux/spinlock.h>
27#include <linux/io.h>
28#include <linux/slab.h>
29
30#define DEFAULT_HEARTBEAT 60
31#define MAX_HEARTBEAT     60
32
33static unsigned int heartbeat = DEFAULT_HEARTBEAT;
34static bool nowayout  = WATCHDOG_NOWAYOUT;
35
36/*
37 * Memory mapping: a single byte, 3 first lower bits to select bit 3
38 * to ping the watchdog.
39 */
40#define MAX6369_WDSET	(7 << 0)
41#define MAX6369_WDI	(1 << 3)
42
43#define MAX6369_WDSET_DISABLED	3
44
45static int nodelay;
46
47struct max63xx_wdt {
48	struct watchdog_device wdd;
49	const struct max63xx_timeout *timeout;
50
51	/* memory mapping */
52	void __iomem *base;
53	spinlock_t lock;
54
55	/* WDI and WSET bits write access routines */
56	void (*ping)(struct max63xx_wdt *wdt);
57	void (*set)(struct max63xx_wdt *wdt, u8 set);
58};
59
60/*
61 * The timeout values used are actually the absolute minimum the chip
62 * offers. Typical values on my board are slightly over twice as long
63 * (10s setting ends up with a 25s timeout), and can be up to 3 times
64 * the nominal setting (according to the datasheet). So please take
65 * these values with a grain of salt. Same goes for the initial delay
66 * "feature". Only max6373/74 have a few settings without this initial
67 * delay (selected with the "nodelay" parameter).
68 *
69 * I also decided to remove from the tables any timeout smaller than a
70 * second, as it looked completly overkill...
71 */
72
73/* Timeouts in second */
74struct max63xx_timeout {
75	const u8 wdset;
76	const u8 tdelay;
77	const u8 twd;
78};
79
80static const struct max63xx_timeout max6369_table[] = {
81	{ 5,  1,  1 },
82	{ 6, 10, 10 },
83	{ 7, 60, 60 },
84	{ },
85};
86
87static const struct max63xx_timeout max6371_table[] = {
88	{ 6, 60,  3 },
89	{ 7, 60, 60 },
90	{ },
91};
92
93static const struct max63xx_timeout max6373_table[] = {
94	{ 2, 60,  1 },
95	{ 5,  0,  1 },
96	{ 1,  3,  3 },
97	{ 7, 60, 10 },
98	{ 6,  0, 10 },
99	{ },
100};
101
102static struct max63xx_timeout *
103max63xx_select_timeout(struct max63xx_timeout *table, int value)
104{
105	while (table->twd) {
106		if (value <= table->twd) {
107			if (nodelay && table->tdelay == 0)
108				return table;
109
110			if (!nodelay)
111				return table;
112		}
113
114		table++;
115	}
116
117	return NULL;
118}
119
120static int max63xx_wdt_ping(struct watchdog_device *wdd)
121{
122	struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
123
124	wdt->ping(wdt);
125	return 0;
126}
127
128static int max63xx_wdt_start(struct watchdog_device *wdd)
129{
130	struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
131
132	wdt->set(wdt, wdt->timeout->wdset);
133
134	/* check for a edge triggered startup */
135	if (wdt->timeout->tdelay == 0)
136		wdt->ping(wdt);
137	return 0;
138}
139
140static int max63xx_wdt_stop(struct watchdog_device *wdd)
141{
142	struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
143
144	wdt->set(wdt, MAX6369_WDSET_DISABLED);
145	return 0;
146}
147
148static const struct watchdog_ops max63xx_wdt_ops = {
149	.owner = THIS_MODULE,
150	.start = max63xx_wdt_start,
151	.stop = max63xx_wdt_stop,
152	.ping = max63xx_wdt_ping,
153};
154
155static const struct watchdog_info max63xx_wdt_info = {
156	.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
157	.identity = "max63xx Watchdog",
158};
159
160static void max63xx_mmap_ping(struct max63xx_wdt *wdt)
161{
162	u8 val;
163
164	spin_lock(&wdt->lock);
165
166	val = __raw_readb(wdt->base);
167
168	__raw_writeb(val | MAX6369_WDI, wdt->base);
169	__raw_writeb(val & ~MAX6369_WDI, wdt->base);
170
171	spin_unlock(&wdt->lock);
172}
173
174static void max63xx_mmap_set(struct max63xx_wdt *wdt, u8 set)
175{
176	u8 val;
177
178	spin_lock(&wdt->lock);
179
180	val = __raw_readb(wdt->base);
181	val &= ~MAX6369_WDSET;
182	val |= set & MAX6369_WDSET;
183	__raw_writeb(val, wdt->base);
184
185	spin_unlock(&wdt->lock);
186}
187
188static int max63xx_mmap_init(struct platform_device *p, struct max63xx_wdt *wdt)
189{
190	wdt->base = devm_platform_ioremap_resource(p, 0);
191	if (IS_ERR(wdt->base))
192		return PTR_ERR(wdt->base);
193
194	spin_lock_init(&wdt->lock);
195
196	wdt->ping = max63xx_mmap_ping;
197	wdt->set = max63xx_mmap_set;
198	return 0;
199}
200
201static int max63xx_wdt_probe(struct platform_device *pdev)
202{
203	struct device *dev = &pdev->dev;
204	struct max63xx_wdt *wdt;
205	struct max63xx_timeout *table;
206	int err;
207
208	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
209	if (!wdt)
210		return -ENOMEM;
211
212	table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
213
214	if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
215		heartbeat = DEFAULT_HEARTBEAT;
216
217	wdt->timeout = max63xx_select_timeout(table, heartbeat);
218	if (!wdt->timeout) {
219		dev_err(dev, "unable to satisfy %ds heartbeat request\n",
220			heartbeat);
221		return -EINVAL;
222	}
223
224	err = max63xx_mmap_init(pdev, wdt);
225	if (err)
226		return err;
227
228	platform_set_drvdata(pdev, &wdt->wdd);
229	watchdog_set_drvdata(&wdt->wdd, wdt);
230
231	wdt->wdd.parent = dev;
232	wdt->wdd.timeout = wdt->timeout->twd;
233	wdt->wdd.info = &max63xx_wdt_info;
234	wdt->wdd.ops = &max63xx_wdt_ops;
235
236	watchdog_set_nowayout(&wdt->wdd, nowayout);
237
238	err = devm_watchdog_register_device(dev, &wdt->wdd);
239	if (err)
240		return err;
241
242	dev_info(dev, "using %ds heartbeat with %ds initial delay\n",
243		 wdt->timeout->twd, wdt->timeout->tdelay);
244	return 0;
245}
246
247static const struct platform_device_id max63xx_id_table[] = {
248	{ "max6369_wdt", (kernel_ulong_t)max6369_table, },
249	{ "max6370_wdt", (kernel_ulong_t)max6369_table, },
250	{ "max6371_wdt", (kernel_ulong_t)max6371_table, },
251	{ "max6372_wdt", (kernel_ulong_t)max6371_table, },
252	{ "max6373_wdt", (kernel_ulong_t)max6373_table, },
253	{ "max6374_wdt", (kernel_ulong_t)max6373_table, },
254	{ },
255};
256MODULE_DEVICE_TABLE(platform, max63xx_id_table);
257
258static struct platform_driver max63xx_wdt_driver = {
259	.probe		= max63xx_wdt_probe,
260	.id_table	= max63xx_id_table,
261	.driver		= {
262		.name	= "max63xx_wdt",
263	},
264};
265
266module_platform_driver(max63xx_wdt_driver);
267
268MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
269MODULE_DESCRIPTION("max63xx Watchdog Driver");
270
271module_param(heartbeat, int, 0);
272MODULE_PARM_DESC(heartbeat,
273		 "Watchdog heartbeat period in seconds from 1 to "
274		 __MODULE_STRING(MAX_HEARTBEAT) ", default "
275		 __MODULE_STRING(DEFAULT_HEARTBEAT));
276
277module_param(nowayout, bool, 0);
278MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
279		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
280
281module_param(nodelay, int, 0);
282MODULE_PARM_DESC(nodelay,
283		 "Force selection of a timeout setting without initial delay "
284		 "(max6373/74 only, default=0)");
285
286MODULE_LICENSE("GPL v2");
287