1/*
2 * Watchdog driver for Cirrus Logic EP93xx family of devices.
3 *
4 * Copyright (c) 2004 Ray Lehtiniemi
5 * Copyright (c) 2006 Tower Technologies
6 * Based on ep93xx driver, bits from alim7101_wdt.c
7 *
8 * Authors: Ray Lehtiniemi <rayl@mail.com>,
9 *	Alessandro Zummo <a.zummo@towertech.it>
10 *
11 * Copyright (c) 2012 H Hartley Sweeten <hsweeten@visionengravers.com>
12 *	Convert to a platform device and use the watchdog framework API
13 *
14 * This file is licensed under the terms of the GNU General Public
15 * License version 2. This program is licensed "as is" without any
16 * warranty of any kind, whether express or implied.
17 *
18 * This watchdog fires after 250msec, which is a too short interval
19 * for us to rely on the user space daemon alone. So we ping the
20 * wdt each ~200msec and eventually stop doing it if the user space
21 * daemon dies.
22 *
23 * TODO:
24 *
25 *	- Test last reset from watchdog status
26 *	- Add a few missing ioctls
27 */
28
29#include <linux/platform_device.h>
30#include <linux/module.h>
31#include <linux/watchdog.h>
32#include <linux/timer.h>
33#include <linux/io.h>
34
35#define WDT_VERSION	"0.4"
36
37/* default timeout (secs) */
38#define WDT_TIMEOUT 30
39
40static bool nowayout = WATCHDOG_NOWAYOUT;
41module_param(nowayout, bool, 0);
42MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
43
44static unsigned int timeout = WDT_TIMEOUT;
45module_param(timeout, uint, 0);
46MODULE_PARM_DESC(timeout,
47	"Watchdog timeout in seconds. (1<=timeout<=3600, default="
48				__MODULE_STRING(WDT_TIMEOUT) ")");
49
50static void __iomem *mmio_base;
51static struct timer_list timer;
52static unsigned long next_heartbeat;
53
54#define EP93XX_WATCHDOG		0x00
55#define EP93XX_WDSTATUS		0x04
56
57/* reset the wdt every ~200ms - the heartbeat of the device is 0.250 seconds*/
58#define WDT_INTERVAL (HZ/5)
59
60static void ep93xx_wdt_timer_ping(unsigned long data)
61{
62	if (time_before(jiffies, next_heartbeat))
63		writel(0x5555, mmio_base + EP93XX_WATCHDOG);
64
65	/* Re-set the timer interval */
66	mod_timer(&timer, jiffies + WDT_INTERVAL);
67}
68
69static int ep93xx_wdt_start(struct watchdog_device *wdd)
70{
71	next_heartbeat = jiffies + (timeout * HZ);
72
73	writel(0xaaaa, mmio_base + EP93XX_WATCHDOG);
74	mod_timer(&timer, jiffies + WDT_INTERVAL);
75
76	return 0;
77}
78
79static int ep93xx_wdt_stop(struct watchdog_device *wdd)
80{
81	del_timer_sync(&timer);
82	writel(0xaa55, mmio_base + EP93XX_WATCHDOG);
83
84	return 0;
85}
86
87static int ep93xx_wdt_keepalive(struct watchdog_device *wdd)
88{
89	/* user land ping */
90	next_heartbeat = jiffies + (timeout * HZ);
91
92	return 0;
93}
94
95static const struct watchdog_info ep93xx_wdt_ident = {
96	.options	= WDIOF_CARDRESET |
97			  WDIOF_MAGICCLOSE |
98			  WDIOF_KEEPALIVEPING,
99	.identity	= "EP93xx Watchdog",
100};
101
102static struct watchdog_ops ep93xx_wdt_ops = {
103	.owner		= THIS_MODULE,
104	.start		= ep93xx_wdt_start,
105	.stop		= ep93xx_wdt_stop,
106	.ping		= ep93xx_wdt_keepalive,
107};
108
109static struct watchdog_device ep93xx_wdt_wdd = {
110	.info		= &ep93xx_wdt_ident,
111	.ops		= &ep93xx_wdt_ops,
112};
113
114static int ep93xx_wdt_probe(struct platform_device *pdev)
115{
116	struct resource *res;
117	unsigned long val;
118	int err;
119
120	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
121	mmio_base = devm_ioremap_resource(&pdev->dev, res);
122	if (IS_ERR(mmio_base))
123		return PTR_ERR(mmio_base);
124
125	if (timeout < 1 || timeout > 3600) {
126		timeout = WDT_TIMEOUT;
127		dev_warn(&pdev->dev,
128			"timeout value must be 1<=x<=3600, using %d\n",
129			timeout);
130	}
131
132	val = readl(mmio_base + EP93XX_WATCHDOG);
133	ep93xx_wdt_wdd.bootstatus = (val & 0x01) ? WDIOF_CARDRESET : 0;
134	ep93xx_wdt_wdd.timeout = timeout;
135	ep93xx_wdt_wdd.parent = &pdev->dev;
136
137	watchdog_set_nowayout(&ep93xx_wdt_wdd, nowayout);
138
139	setup_timer(&timer, ep93xx_wdt_timer_ping, 1);
140
141	err = watchdog_register_device(&ep93xx_wdt_wdd);
142	if (err)
143		return err;
144
145	dev_info(&pdev->dev,
146		"EP93XX watchdog, driver version " WDT_VERSION "%s\n",
147		(val & 0x08) ? " (nCS1 disable detected)" : "");
148
149	return 0;
150}
151
152static int ep93xx_wdt_remove(struct platform_device *pdev)
153{
154	watchdog_unregister_device(&ep93xx_wdt_wdd);
155	return 0;
156}
157
158static struct platform_driver ep93xx_wdt_driver = {
159	.driver		= {
160		.name	= "ep93xx-wdt",
161	},
162	.probe		= ep93xx_wdt_probe,
163	.remove		= ep93xx_wdt_remove,
164};
165
166module_platform_driver(ep93xx_wdt_driver);
167
168MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>");
169MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
170MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
171MODULE_DESCRIPTION("EP93xx Watchdog");
172MODULE_LICENSE("GPL");
173MODULE_VERSION(WDT_VERSION);
174