1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Watchdog driver for Cirrus Logic EP93xx family of devices.
4 *
5 * Copyright (c) 2004 Ray Lehtiniemi
6 * Copyright (c) 2006 Tower Technologies
7 * Based on ep93xx driver, bits from alim7101_wdt.c
8 *
9 * Authors: Ray Lehtiniemi <rayl@mail.com>,
10 *	Alessandro Zummo <a.zummo@towertech.it>
11 *
12 * Copyright (c) 2012 H Hartley Sweeten <hsweeten@visionengravers.com>
13 *	Convert to a platform device and use the watchdog framework API
14 *
15 * This watchdog fires after 250msec, which is a too short interval
16 * for us to rely on the user space daemon alone. So we ping the
17 * wdt each ~200msec and eventually stop doing it if the user space
18 * daemon dies.
19 */
20
21#include <linux/platform_device.h>
22#include <linux/module.h>
23#include <linux/watchdog.h>
24#include <linux/io.h>
25
26/* default timeout (secs) */
27#define WDT_TIMEOUT 30
28
29static bool nowayout = WATCHDOG_NOWAYOUT;
30module_param(nowayout, bool, 0);
31MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
32
33static unsigned int timeout;
34module_param(timeout, uint, 0);
35MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds.");
36
37#define EP93XX_WATCHDOG		0x00
38#define EP93XX_WDSTATUS		0x04
39
40struct ep93xx_wdt_priv {
41	void __iomem *mmio;
42	struct watchdog_device wdd;
43};
44
45static int ep93xx_wdt_start(struct watchdog_device *wdd)
46{
47	struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
48
49	writel(0xaaaa, priv->mmio + EP93XX_WATCHDOG);
50
51	return 0;
52}
53
54static int ep93xx_wdt_stop(struct watchdog_device *wdd)
55{
56	struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
57
58	writel(0xaa55, priv->mmio + EP93XX_WATCHDOG);
59
60	return 0;
61}
62
63static int ep93xx_wdt_ping(struct watchdog_device *wdd)
64{
65	struct ep93xx_wdt_priv *priv = watchdog_get_drvdata(wdd);
66
67	writel(0x5555, priv->mmio + EP93XX_WATCHDOG);
68
69	return 0;
70}
71
72static const struct watchdog_info ep93xx_wdt_ident = {
73	.options	= WDIOF_CARDRESET |
74			  WDIOF_SETTIMEOUT |
75			  WDIOF_MAGICCLOSE |
76			  WDIOF_KEEPALIVEPING,
77	.identity	= "EP93xx Watchdog",
78};
79
80static const struct watchdog_ops ep93xx_wdt_ops = {
81	.owner		= THIS_MODULE,
82	.start		= ep93xx_wdt_start,
83	.stop		= ep93xx_wdt_stop,
84	.ping		= ep93xx_wdt_ping,
85};
86
87static int ep93xx_wdt_probe(struct platform_device *pdev)
88{
89	struct device *dev = &pdev->dev;
90	struct ep93xx_wdt_priv *priv;
91	struct watchdog_device *wdd;
92	unsigned long val;
93	int ret;
94
95	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
96	if (!priv)
97		return -ENOMEM;
98
99	priv->mmio = devm_platform_ioremap_resource(pdev, 0);
100	if (IS_ERR(priv->mmio))
101		return PTR_ERR(priv->mmio);
102
103	val = readl(priv->mmio + EP93XX_WATCHDOG);
104
105	wdd = &priv->wdd;
106	wdd->bootstatus = (val & 0x01) ? WDIOF_CARDRESET : 0;
107	wdd->info = &ep93xx_wdt_ident;
108	wdd->ops = &ep93xx_wdt_ops;
109	wdd->min_timeout = 1;
110	wdd->max_hw_heartbeat_ms = 200;
111	wdd->parent = dev;
112
113	watchdog_set_nowayout(wdd, nowayout);
114
115	wdd->timeout = WDT_TIMEOUT;
116	watchdog_init_timeout(wdd, timeout, dev);
117
118	watchdog_set_drvdata(wdd, priv);
119
120	ret = devm_watchdog_register_device(dev, wdd);
121	if (ret)
122		return ret;
123
124	dev_info(dev, "EP93XX watchdog driver %s\n",
125		 (val & 0x08) ? " (nCS1 disable detected)" : "");
126
127	return 0;
128}
129
130static struct platform_driver ep93xx_wdt_driver = {
131	.driver		= {
132		.name	= "ep93xx-wdt",
133	},
134	.probe		= ep93xx_wdt_probe,
135};
136
137module_platform_driver(ep93xx_wdt_driver);
138
139MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>");
140MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
141MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
142MODULE_DESCRIPTION("EP93xx Watchdog");
143MODULE_LICENSE("GPL");
144