1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Retu watchdog driver
4 *
5 * Copyright (C) 2004, 2005 Nokia Corporation
6 *
7 * Based on code written by Amit Kucheria and Michael Buesch.
8 * Rewritten by Aaro Koskinen.
9 */
10
11#include <linux/slab.h>
12#include <linux/errno.h>
13#include <linux/device.h>
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/mfd/retu.h>
17#include <linux/watchdog.h>
18#include <linux/platform_device.h>
19
20/* Watchdog timer values in seconds */
21#define RETU_WDT_MAX_TIMER	63
22
23struct retu_wdt_dev {
24	struct retu_dev		*rdev;
25	struct device		*dev;
26	struct delayed_work	ping_work;
27};
28
29/*
30 * Since Retu watchdog cannot be disabled in hardware, we must kick it
31 * with a timer until userspace watchdog software takes over. If
32 * CONFIG_WATCHDOG_NOWAYOUT is set, we never start the feeding.
33 */
34static void retu_wdt_ping_enable(struct retu_wdt_dev *wdev)
35{
36	retu_write(wdev->rdev, RETU_REG_WATCHDOG, RETU_WDT_MAX_TIMER);
37	schedule_delayed_work(&wdev->ping_work,
38			round_jiffies_relative(RETU_WDT_MAX_TIMER * HZ / 2));
39}
40
41static void retu_wdt_ping_disable(struct retu_wdt_dev *wdev)
42{
43	retu_write(wdev->rdev, RETU_REG_WATCHDOG, RETU_WDT_MAX_TIMER);
44	cancel_delayed_work_sync(&wdev->ping_work);
45}
46
47static void retu_wdt_ping_work(struct work_struct *work)
48{
49	struct retu_wdt_dev *wdev = container_of(to_delayed_work(work),
50						struct retu_wdt_dev, ping_work);
51	retu_wdt_ping_enable(wdev);
52}
53
54static int retu_wdt_start(struct watchdog_device *wdog)
55{
56	struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);
57
58	retu_wdt_ping_disable(wdev);
59
60	return retu_write(wdev->rdev, RETU_REG_WATCHDOG, wdog->timeout);
61}
62
63static int retu_wdt_stop(struct watchdog_device *wdog)
64{
65	struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);
66
67	retu_wdt_ping_enable(wdev);
68
69	return 0;
70}
71
72static int retu_wdt_ping(struct watchdog_device *wdog)
73{
74	struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);
75
76	return retu_write(wdev->rdev, RETU_REG_WATCHDOG, wdog->timeout);
77}
78
79static int retu_wdt_set_timeout(struct watchdog_device *wdog,
80				unsigned int timeout)
81{
82	struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);
83
84	wdog->timeout = timeout;
85	return retu_write(wdev->rdev, RETU_REG_WATCHDOG, wdog->timeout);
86}
87
88static const struct watchdog_info retu_wdt_info = {
89	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
90	.identity = "Retu watchdog",
91};
92
93static const struct watchdog_ops retu_wdt_ops = {
94	.owner		= THIS_MODULE,
95	.start		= retu_wdt_start,
96	.stop		= retu_wdt_stop,
97	.ping		= retu_wdt_ping,
98	.set_timeout	= retu_wdt_set_timeout,
99};
100
101static int retu_wdt_probe(struct platform_device *pdev)
102{
103	struct retu_dev *rdev = dev_get_drvdata(pdev->dev.parent);
104	bool nowayout = WATCHDOG_NOWAYOUT;
105	struct watchdog_device *retu_wdt;
106	struct retu_wdt_dev *wdev;
107	int ret;
108
109	retu_wdt = devm_kzalloc(&pdev->dev, sizeof(*retu_wdt), GFP_KERNEL);
110	if (!retu_wdt)
111		return -ENOMEM;
112
113	wdev = devm_kzalloc(&pdev->dev, sizeof(*wdev), GFP_KERNEL);
114	if (!wdev)
115		return -ENOMEM;
116
117	retu_wdt->info		= &retu_wdt_info;
118	retu_wdt->ops		= &retu_wdt_ops;
119	retu_wdt->timeout	= RETU_WDT_MAX_TIMER;
120	retu_wdt->min_timeout	= 0;
121	retu_wdt->max_timeout	= RETU_WDT_MAX_TIMER;
122	retu_wdt->parent	= &pdev->dev;
123
124	watchdog_set_drvdata(retu_wdt, wdev);
125	watchdog_set_nowayout(retu_wdt, nowayout);
126
127	wdev->rdev		= rdev;
128	wdev->dev		= &pdev->dev;
129
130	INIT_DELAYED_WORK(&wdev->ping_work, retu_wdt_ping_work);
131
132	ret = watchdog_register_device(retu_wdt);
133	if (ret < 0)
134		return ret;
135
136	if (nowayout)
137		retu_wdt_ping(retu_wdt);
138	else
139		retu_wdt_ping_enable(wdev);
140
141	platform_set_drvdata(pdev, retu_wdt);
142
143	return 0;
144}
145
146static int retu_wdt_remove(struct platform_device *pdev)
147{
148	struct watchdog_device *wdog = platform_get_drvdata(pdev);
149	struct retu_wdt_dev *wdev = watchdog_get_drvdata(wdog);
150
151	watchdog_unregister_device(wdog);
152	cancel_delayed_work_sync(&wdev->ping_work);
153
154	return 0;
155}
156
157static struct platform_driver retu_wdt_driver = {
158	.probe		= retu_wdt_probe,
159	.remove		= retu_wdt_remove,
160	.driver		= {
161		.name	= "retu-wdt",
162	},
163};
164module_platform_driver(retu_wdt_driver);
165
166MODULE_ALIAS("platform:retu-wdt");
167MODULE_DESCRIPTION("Retu watchdog");
168MODULE_AUTHOR("Amit Kucheria");
169MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>");
170MODULE_LICENSE("GPL");
171