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
24#include <linux/platform_device.h>
25#include <linux/module.h>
26#include <linux/watchdog.h>
27#include <linux/io.h>
28
29/* default timeout (secs) */
30#define WDT_TIMEOUT 30
31
32static bool nowayout = WATCHDOG_NOWAYOUT;
33module_param(nowayout, bool, 0);
34MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
35
36static unsigned int timeout;
37module_param(timeout, uint, 0);
38MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds.");
39
40#define EP93XX_WATCHDOG		0x00
41#define EP93XX_WDSTATUS		0x04
42
43struct ep93xx_wdt_priv {
44	void __iomem *mmio;
45	struct watchdog_device wdd;
46};
47
48static int ep93xx_wdt_start(struct watchdog_device *wdd)
49{
50	struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
51
52	writel(0xaaaa, priv->mmio + EP93XX_WATCHDOG);
53
54	return 0;
55}
56
57static int ep93xx_wdt_stop(struct watchdog_device *wdd)
58{
59	struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
60
61	writel(0xaa55, priv->mmio + EP93XX_WATCHDOG);
62
63	return 0;
64}
65
66static int ep93xx_wdt_ping(struct watchdog_device *wdd)
67{
68	struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
69
70	writel(0x5555, priv->mmio + EP93XX_WATCHDOG);
71
72	return 0;
73}
74
75static const struct watchdog_info ep93xx_wdt_ident = {
76	.options	= WDIOF_CARDRESET |
77			  WDIOF_SETTIMEOUT |
78			  WDIOF_MAGICCLOSE |
79			  WDIOF_KEEPALIVEPING,
80	.identity	= "EP93xx Watchdog",
81};
82
83static const struct watchdog_ops ep93xx_wdt_ops = {
84	.owner		= THIS_MODULE,
85	.start		= ep93xx_wdt_start,
86	.stop		= ep93xx_wdt_stop,
87	.ping		= ep93xx_wdt_ping,
88};
89
90static int ep93xx_wdt_probe(struct platform_device *pdev)
91{
92	struct device *dev = &pdev->dev;
93	struct ep93xx_wdt_priv *priv;
94	struct watchdog_device *wdd;
95	unsigned long val;
96	int ret;
97
98	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
99	if (!priv)
100		return -ENOMEM;
101
102	priv->mmio = devm_platform_ioremap_resource(pdev, 0);
103	if (IS_ERR(priv->mmio))
104		return PTR_ERR(priv->mmio);
105
106	val = readl(priv->mmio + EP93XX_WATCHDOG);
107
108	wdd = &priv->wdd;
109	wdd->bootstatus = (val & 0x01) ? WDIOF_CARDRESET : 0;
110	wdd->info = &ep93xx_wdt_ident;
111	wdd->ops = &ep93xx_wdt_ops;
112	wdd->min_timeout = 1;
113	wdd->max_hw_heartbeat_ms = 200;
114	wdd->parent = dev;
115
116	watchdog_set_nowayout(wdd, nowayout);
117
118	wdd->timeout = WDT_TIMEOUT;
119	watchdog_init_timeout(wdd, timeout, dev);
120
121	watchdog_set_drvdata(wdd, priv);
122
123	ret = devm_watchdog_register_device(dev, wdd);
124	if (ret)
125		return ret;
126
127	dev_info(dev, "EP93XX watchdog driver %s\n",
128		 (val & 0x08) ? " (nCS1 disable detected)" : "");
129
130	return 0;
131}
132
133static struct platform_driver ep93xx_wdt_driver = {
134	.driver		= {
135		.name	= "ep93xx-wdt",
136	},
137	.probe		= ep93xx_wdt_probe,
138};
139
140module_platform_driver(ep93xx_wdt_driver);
141
142MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>");
143MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
144MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
145MODULE_DESCRIPTION("EP93xx Watchdog");
146MODULE_LICENSE("GPL");
147