1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * drivers/char/watchdog/max63xx_wdt.c
4 *
5 * Driver for max63{69,70,71,72,73,74} watchdog timers
6 *
7 * Copyright (C) 2009 Marc Zyngier <maz@misterjones.org>
8 *
9 * This driver assumes the watchdog pins are memory mapped (as it is
10 * the case for the Arcom Zeus). Should it be connected over GPIOs or
11 * another interface, some abstraction will have to be introduced.
12 */
13
14#include <linux/err.h>
15#include <linux/module.h>
16#include <linux/moduleparam.h>
17#include <linux/mod_devicetable.h>
18#include <linux/types.h>
19#include <linux/kernel.h>
20#include <linux/watchdog.h>
21#include <linux/bitops.h>
22#include <linux/platform_device.h>
23#include <linux/spinlock.h>
24#include <linux/io.h>
25#include <linux/slab.h>
26#include <linux/property.h>
27
28#define DEFAULT_HEARTBEAT 60
29#define MAX_HEARTBEAT     60
30
31static unsigned int heartbeat = DEFAULT_HEARTBEAT;
32static bool nowayout  = WATCHDOG_NOWAYOUT;
33
34/*
35 * Memory mapping: a single byte, 3 first lower bits to select bit 3
36 * to ping the watchdog.
37 */
38#define MAX6369_WDSET	(7 << 0)
39#define MAX6369_WDI	(1 << 3)
40
41#define MAX6369_WDSET_DISABLED	3
42
43static int nodelay;
44
45struct max63xx_wdt {
46	struct watchdog_device wdd;
47	const struct max63xx_timeout *timeout;
48
49	/* memory mapping */
50	void __iomem *base;
51	spinlock_t lock;
52
53	/* WDI and WSET bits write access routines */
54	void (*ping)(struct max63xx_wdt *wdt);
55	void (*set)(struct max63xx_wdt *wdt, u8 set);
56};
57
58/*
59 * The timeout values used are actually the absolute minimum the chip
60 * offers. Typical values on my board are slightly over twice as long
61 * (10s setting ends up with a 25s timeout), and can be up to 3 times
62 * the nominal setting (according to the datasheet). So please take
63 * these values with a grain of salt. Same goes for the initial delay
64 * "feature". Only max6373/74 have a few settings without this initial
65 * delay (selected with the "nodelay" parameter).
66 *
67 * I also decided to remove from the tables any timeout smaller than a
68 * second, as it looked completly overkill...
69 */
70
71/* Timeouts in second */
72struct max63xx_timeout {
73	const u8 wdset;
74	const u8 tdelay;
75	const u8 twd;
76};
77
78static const struct max63xx_timeout max6369_table[] = {
79	{ 5,  1,  1 },
80	{ 6, 10, 10 },
81	{ 7, 60, 60 },
82	{ },
83};
84
85static const struct max63xx_timeout max6371_table[] = {
86	{ 6, 60,  3 },
87	{ 7, 60, 60 },
88	{ },
89};
90
91static const struct max63xx_timeout max6373_table[] = {
92	{ 2, 60,  1 },
93	{ 5,  0,  1 },
94	{ 1,  3,  3 },
95	{ 7, 60, 10 },
96	{ 6,  0, 10 },
97	{ },
98};
99
100static const struct max63xx_timeout *
101max63xx_select_timeout(const struct max63xx_timeout *table, int value)
102{
103	while (table->twd) {
104		if (value <= table->twd) {
105			if (nodelay && table->tdelay == 0)
106				return table;
107
108			if (!nodelay)
109				return table;
110		}
111
112		table++;
113	}
114
115	return NULL;
116}
117
118static int max63xx_wdt_ping(struct watchdog_device *wdd)
119{
120	struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
121
122	wdt->ping(wdt);
123	return 0;
124}
125
126static int max63xx_wdt_start(struct watchdog_device *wdd)
127{
128	struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
129
130	wdt->set(wdt, wdt->timeout->wdset);
131
132	/* check for a edge triggered startup */
133	if (wdt->timeout->tdelay == 0)
134		wdt->ping(wdt);
135	return 0;
136}
137
138static int max63xx_wdt_stop(struct watchdog_device *wdd)
139{
140	struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
141
142	wdt->set(wdt, MAX6369_WDSET_DISABLED);
143	return 0;
144}
145
146static const struct watchdog_ops max63xx_wdt_ops = {
147	.owner = THIS_MODULE,
148	.start = max63xx_wdt_start,
149	.stop = max63xx_wdt_stop,
150	.ping = max63xx_wdt_ping,
151};
152
153static const struct watchdog_info max63xx_wdt_info = {
154	.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
155	.identity = "max63xx Watchdog",
156};
157
158static void max63xx_mmap_ping(struct max63xx_wdt *wdt)
159{
160	u8 val;
161
162	spin_lock(&wdt->lock);
163
164	val = __raw_readb(wdt->base);
165
166	__raw_writeb(val | MAX6369_WDI, wdt->base);
167	__raw_writeb(val & ~MAX6369_WDI, wdt->base);
168
169	spin_unlock(&wdt->lock);
170}
171
172static void max63xx_mmap_set(struct max63xx_wdt *wdt, u8 set)
173{
174	u8 val;
175
176	spin_lock(&wdt->lock);
177
178	val = __raw_readb(wdt->base);
179	val &= ~MAX6369_WDSET;
180	val |= set & MAX6369_WDSET;
181	__raw_writeb(val, wdt->base);
182
183	spin_unlock(&wdt->lock);
184}
185
186static int max63xx_mmap_init(struct platform_device *p, struct max63xx_wdt *wdt)
187{
188	wdt->base = devm_platform_ioremap_resource(p, 0);
189	if (IS_ERR(wdt->base))
190		return PTR_ERR(wdt->base);
191
192	spin_lock_init(&wdt->lock);
193
194	wdt->ping = max63xx_mmap_ping;
195	wdt->set = max63xx_mmap_set;
196	return 0;
197}
198
199static int max63xx_wdt_probe(struct platform_device *pdev)
200{
201	struct device *dev = &pdev->dev;
202	struct max63xx_wdt *wdt;
203	const struct max63xx_timeout *table;
204	int err;
205
206	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
207	if (!wdt)
208		return -ENOMEM;
209
210	/* Attempt to use fwnode first */
211	table = device_get_match_data(dev);
212	if (!table)
213		table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
214
215	if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
216		heartbeat = DEFAULT_HEARTBEAT;
217
218	wdt->timeout = max63xx_select_timeout(table, heartbeat);
219	if (!wdt->timeout) {
220		dev_err(dev, "unable to satisfy %ds heartbeat request\n",
221			heartbeat);
222		return -EINVAL;
223	}
224
225	err = max63xx_mmap_init(pdev, wdt);
226	if (err)
227		return err;
228
229	platform_set_drvdata(pdev, &wdt->wdd);
230	watchdog_set_drvdata(&wdt->wdd, wdt);
231
232	wdt->wdd.parent = dev;
233	wdt->wdd.timeout = wdt->timeout->twd;
234	wdt->wdd.info = &max63xx_wdt_info;
235	wdt->wdd.ops = &max63xx_wdt_ops;
236
237	watchdog_set_nowayout(&wdt->wdd, nowayout);
238
239	err = devm_watchdog_register_device(dev, &wdt->wdd);
240	if (err)
241		return err;
242
243	dev_info(dev, "using %ds heartbeat with %ds initial delay\n",
244		 wdt->timeout->twd, wdt->timeout->tdelay);
245	return 0;
246}
247
248static const struct platform_device_id max63xx_id_table[] = {
249	{ "max6369_wdt", (kernel_ulong_t)max6369_table, },
250	{ "max6370_wdt", (kernel_ulong_t)max6369_table, },
251	{ "max6371_wdt", (kernel_ulong_t)max6371_table, },
252	{ "max6372_wdt", (kernel_ulong_t)max6371_table, },
253	{ "max6373_wdt", (kernel_ulong_t)max6373_table, },
254	{ "max6374_wdt", (kernel_ulong_t)max6373_table, },
255	{ },
256};
257MODULE_DEVICE_TABLE(platform, max63xx_id_table);
258
259static const struct of_device_id max63xx_dt_id_table[] = {
260	{ .compatible = "maxim,max6369", .data = max6369_table, },
261	{ .compatible = "maxim,max6370", .data = max6369_table, },
262	{ .compatible = "maxim,max6371", .data = max6371_table, },
263	{ .compatible = "maxim,max6372", .data = max6371_table, },
264	{ .compatible = "maxim,max6373", .data = max6373_table, },
265	{ .compatible = "maxim,max6374", .data = max6373_table, },
266	{ }
267};
268MODULE_DEVICE_TABLE(of, max63xx_dt_id_table);
269
270static struct platform_driver max63xx_wdt_driver = {
271	.probe		= max63xx_wdt_probe,
272	.id_table	= max63xx_id_table,
273	.driver		= {
274		.name	= "max63xx_wdt",
275		.of_match_table = max63xx_dt_id_table,
276	},
277};
278
279module_platform_driver(max63xx_wdt_driver);
280
281MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
282MODULE_DESCRIPTION("max63xx Watchdog Driver");
283
284module_param(heartbeat, int, 0);
285MODULE_PARM_DESC(heartbeat,
286		 "Watchdog heartbeat period in seconds from 1 to "
287		 __MODULE_STRING(MAX_HEARTBEAT) ", default "
288		 __MODULE_STRING(DEFAULT_HEARTBEAT));
289
290module_param(nowayout, bool, 0);
291MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
292		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
293
294module_param(nodelay, int, 0);
295MODULE_PARM_DESC(nodelay,
296		 "Force selection of a timeout setting without initial delay "
297		 "(max6373/74 only, default=0)");
298
299MODULE_LICENSE("GPL v2");
300