tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
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/types.h>
21#include <linux/kernel.h>
22#include <linux/miscdevice.h>
23#include <linux/watchdog.h>
24#include <linux/init.h>
25#include <linux/bitops.h>
26#include <linux/platform_device.h>
27#include <linux/spinlock.h>
28#include <linux/io.h>
29#include <linux/slab.h>
30
31#define DEFAULT_HEARTBEAT 60
32#define MAX_HEARTBEAT 60
33
34static unsigned int heartbeat = DEFAULT_HEARTBEAT;
35static bool nowayout = WATCHDOG_NOWAYOUT;
36
37/*
38 * Memory mapping: a single byte, 3 first lower bits to select bit 3
39 * to ping the watchdog.
40 */
41#define MAX6369_WDSET (7 << 0)
42#define MAX6369_WDI (1 << 3)
43
44static DEFINE_SPINLOCK(io_lock);
45
46static int nodelay;
47static void __iomem *wdt_base;
48
49/*
50 * The timeout values used are actually the absolute minimum the chip
51 * offers. Typical values on my board are slightly over twice as long
52 * (10s setting ends up with a 25s timeout), and can be up to 3 times
53 * the nominal setting (according to the datasheet). So please take
54 * these values with a grain of salt. Same goes for the initial delay
55 * "feature". Only max6373/74 have a few settings without this initial
56 * delay (selected with the "nodelay" parameter).
57 *
58 * I also decided to remove from the tables any timeout smaller than a
59 * second, as it looked completly overkill...
60 */
61
62/* Timeouts in second */
63struct max63xx_timeout {
64 u8 wdset;
65 u8 tdelay;
66 u8 twd;
67};
68
69static struct max63xx_timeout max6369_table[] = {
70 { 5, 1, 1 },
71 { 6, 10, 10 },
72 { 7, 60, 60 },
73 { },
74};
75
76static struct max63xx_timeout max6371_table[] = {
77 { 6, 60, 3 },
78 { 7, 60, 60 },
79 { },
80};
81
82static struct max63xx_timeout max6373_table[] = {
83 { 2, 60, 1 },
84 { 5, 0, 1 },
85 { 1, 3, 3 },
86 { 7, 60, 10 },
87 { 6, 0, 10 },
88 { },
89};
90
91static struct max63xx_timeout *current_timeout;
92
93static struct max63xx_timeout *
94max63xx_select_timeout(struct max63xx_timeout *table, int value)
95{
96 while (table->twd) {
97 if (value <= table->twd) {
98 if (nodelay && table->tdelay == 0)
99 return table;
100
101 if (!nodelay)
102 return table;
103 }
104
105 table++;
106 }
107
108 return NULL;
109}
110
111static int max63xx_wdt_ping(struct watchdog_device *wdd)
112{
113 u8 val;
114
115 spin_lock(&io_lock);
116
117 val = __raw_readb(wdt_base);
118
119 __raw_writeb(val | MAX6369_WDI, wdt_base);
120 __raw_writeb(val & ~MAX6369_WDI, wdt_base);
121
122 spin_unlock(&io_lock);
123 return 0;
124}
125
126static int max63xx_wdt_start(struct watchdog_device *wdd)
127{
128 struct max63xx_timeout *entry = watchdog_get_drvdata(wdd);
129 u8 val;
130
131 spin_lock(&io_lock);
132
133 val = __raw_readb(wdt_base);
134 val &= ~MAX6369_WDSET;
135 val |= entry->wdset;
136 __raw_writeb(val, wdt_base);
137
138 spin_unlock(&io_lock);
139
140 /* check for a edge triggered startup */
141 if (entry->tdelay == 0)
142 max63xx_wdt_ping(wdd);
143 return 0;
144}
145
146static int max63xx_wdt_stop(struct watchdog_device *wdd)
147{
148 u8 val;
149
150 spin_lock(&io_lock);
151
152 val = __raw_readb(wdt_base);
153 val &= ~MAX6369_WDSET;
154 val |= 3;
155 __raw_writeb(val, wdt_base);
156
157 spin_unlock(&io_lock);
158 return 0;
159}
160
161static const struct watchdog_info max63xx_wdt_info = {
162 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
163 .identity = "max63xx Watchdog",
164};
165
166static const struct watchdog_ops max63xx_wdt_ops = {
167 .owner = THIS_MODULE,
168 .start = max63xx_wdt_start,
169 .stop = max63xx_wdt_stop,
170 .ping = max63xx_wdt_ping,
171};
172
173static struct watchdog_device max63xx_wdt_dev = {
174 .info = &max63xx_wdt_info,
175 .ops = &max63xx_wdt_ops,
176};
177
178static int max63xx_wdt_probe(struct platform_device *pdev)
179{
180 struct resource *wdt_mem;
181 struct max63xx_timeout *table;
182
183 table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
184
185 if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
186 heartbeat = DEFAULT_HEARTBEAT;
187
188 dev_info(&pdev->dev, "requesting %ds heartbeat\n", heartbeat);
189 current_timeout = max63xx_select_timeout(table, heartbeat);
190
191 if (!current_timeout) {
192 dev_err(&pdev->dev, "unable to satisfy heartbeat request\n");
193 return -EINVAL;
194 }
195
196 dev_info(&pdev->dev, "using %ds heartbeat with %ds initial delay\n",
197 current_timeout->twd, current_timeout->tdelay);
198
199 heartbeat = current_timeout->twd;
200
201 wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
202 wdt_base = devm_ioremap_resource(&pdev->dev, wdt_mem);
203 if (IS_ERR(wdt_base))
204 return PTR_ERR(wdt_base);
205
206 max63xx_wdt_dev.timeout = heartbeat;
207 watchdog_set_nowayout(&max63xx_wdt_dev, nowayout);
208 watchdog_set_drvdata(&max63xx_wdt_dev, current_timeout);
209
210 return watchdog_register_device(&max63xx_wdt_dev);
211}
212
213static int max63xx_wdt_remove(struct platform_device *pdev)
214{
215 watchdog_unregister_device(&max63xx_wdt_dev);
216 return 0;
217}
218
219static struct platform_device_id max63xx_id_table[] = {
220 { "max6369_wdt", (kernel_ulong_t)max6369_table, },
221 { "max6370_wdt", (kernel_ulong_t)max6369_table, },
222 { "max6371_wdt", (kernel_ulong_t)max6371_table, },
223 { "max6372_wdt", (kernel_ulong_t)max6371_table, },
224 { "max6373_wdt", (kernel_ulong_t)max6373_table, },
225 { "max6374_wdt", (kernel_ulong_t)max6373_table, },
226 { },
227};
228MODULE_DEVICE_TABLE(platform, max63xx_id_table);
229
230static struct platform_driver max63xx_wdt_driver = {
231 .probe = max63xx_wdt_probe,
232 .remove = max63xx_wdt_remove,
233 .id_table = max63xx_id_table,
234 .driver = {
235 .name = "max63xx_wdt",
236 .owner = THIS_MODULE,
237 },
238};
239
240module_platform_driver(max63xx_wdt_driver);
241
242MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
243MODULE_DESCRIPTION("max63xx Watchdog Driver");
244
245module_param(heartbeat, int, 0);
246MODULE_PARM_DESC(heartbeat,
247 "Watchdog heartbeat period in seconds from 1 to "
248 __MODULE_STRING(MAX_HEARTBEAT) ", default "
249 __MODULE_STRING(DEFAULT_HEARTBEAT));
250
251module_param(nowayout, bool, 0);
252MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
253 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
254
255module_param(nodelay, int, 0);
256MODULE_PARM_DESC(nodelay,
257 "Force selection of a timeout setting without initial delay "
258 "(max6373/74 only, default=0)");
259
260MODULE_LICENSE("GPL");
261MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);