1/*
2 *      Meson Watchdog Driver
3 *
4 *      Copyright (c) 2014 Carlo Caione
5 *
6 *      This program is free software; you can redistribute it and/or
7 *      modify it under the terms of the GNU General Public License
8 *      as published by the Free Software Foundation; either version
9 *      2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/clk.h>
13#include <linux/delay.h>
14#include <linux/err.h>
15#include <linux/init.h>
16#include <linux/io.h>
17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/moduleparam.h>
20#include <linux/notifier.h>
21#include <linux/of.h>
22#include <linux/platform_device.h>
23#include <linux/reboot.h>
24#include <linux/types.h>
25#include <linux/watchdog.h>
26
27#define DRV_NAME		"meson_wdt"
28
29#define MESON_WDT_TC		0x00
30#define MESON_WDT_TC_EN		BIT(22)
31#define MESON_WDT_TC_TM_MASK	0x3fffff
32#define MESON_WDT_DC_RESET	(3 << 24)
33
34#define MESON_WDT_RESET		0x04
35
36#define MESON_WDT_TIMEOUT	30
37#define MESON_WDT_MIN_TIMEOUT	1
38#define MESON_WDT_MAX_TIMEOUT	(MESON_WDT_TC_TM_MASK / 100000)
39
40#define MESON_SEC_TO_TC(s)	((s) * 100000)
41
42static bool nowayout = WATCHDOG_NOWAYOUT;
43static unsigned int timeout = MESON_WDT_TIMEOUT;
44
45struct meson_wdt_dev {
46	struct watchdog_device wdt_dev;
47	void __iomem *wdt_base;
48	struct notifier_block restart_handler;
49};
50
51static int meson_restart_handle(struct notifier_block *this, unsigned long mode,
52				void *cmd)
53{
54	u32 tc_reboot = MESON_WDT_DC_RESET | MESON_WDT_TC_EN;
55	struct meson_wdt_dev *meson_wdt = container_of(this,
56						       struct meson_wdt_dev,
57						       restart_handler);
58
59	while (1) {
60		writel(tc_reboot, meson_wdt->wdt_base + MESON_WDT_TC);
61		mdelay(5);
62	}
63
64	return NOTIFY_DONE;
65}
66
67static int meson_wdt_ping(struct watchdog_device *wdt_dev)
68{
69	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
70
71	writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
72
73	return 0;
74}
75
76static void meson_wdt_change_timeout(struct watchdog_device *wdt_dev,
77				     unsigned int timeout)
78{
79	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
80	u32 reg;
81
82	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
83	reg &= ~MESON_WDT_TC_TM_MASK;
84	reg |= MESON_SEC_TO_TC(timeout);
85	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
86}
87
88static int meson_wdt_set_timeout(struct watchdog_device *wdt_dev,
89				 unsigned int timeout)
90{
91	wdt_dev->timeout = timeout;
92
93	meson_wdt_change_timeout(wdt_dev, timeout);
94	meson_wdt_ping(wdt_dev);
95
96	return 0;
97}
98
99static int meson_wdt_stop(struct watchdog_device *wdt_dev)
100{
101	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
102	u32 reg;
103
104	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
105	reg &= ~MESON_WDT_TC_EN;
106	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
107
108	return 0;
109}
110
111static int meson_wdt_start(struct watchdog_device *wdt_dev)
112{
113	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
114	u32 reg;
115
116	meson_wdt_change_timeout(wdt_dev, meson_wdt->wdt_dev.timeout);
117	meson_wdt_ping(wdt_dev);
118
119	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
120	reg |= MESON_WDT_TC_EN;
121	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
122
123	return 0;
124}
125
126static const struct watchdog_info meson_wdt_info = {
127	.identity	= DRV_NAME,
128	.options	= WDIOF_SETTIMEOUT |
129			  WDIOF_KEEPALIVEPING |
130			  WDIOF_MAGICCLOSE,
131};
132
133static const struct watchdog_ops meson_wdt_ops = {
134	.owner		= THIS_MODULE,
135	.start		= meson_wdt_start,
136	.stop		= meson_wdt_stop,
137	.ping		= meson_wdt_ping,
138	.set_timeout	= meson_wdt_set_timeout,
139};
140
141static int meson_wdt_probe(struct platform_device *pdev)
142{
143	struct resource *res;
144	struct meson_wdt_dev *meson_wdt;
145	int err;
146
147	meson_wdt = devm_kzalloc(&pdev->dev, sizeof(*meson_wdt), GFP_KERNEL);
148	if (!meson_wdt)
149		return -ENOMEM;
150
151	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
152	meson_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
153	if (IS_ERR(meson_wdt->wdt_base))
154		return PTR_ERR(meson_wdt->wdt_base);
155
156	meson_wdt->wdt_dev.parent = &pdev->dev;
157	meson_wdt->wdt_dev.info = &meson_wdt_info;
158	meson_wdt->wdt_dev.ops = &meson_wdt_ops;
159	meson_wdt->wdt_dev.timeout = MESON_WDT_TIMEOUT;
160	meson_wdt->wdt_dev.max_timeout = MESON_WDT_MAX_TIMEOUT;
161	meson_wdt->wdt_dev.min_timeout = MESON_WDT_MIN_TIMEOUT;
162
163	watchdog_set_drvdata(&meson_wdt->wdt_dev, meson_wdt);
164
165	watchdog_init_timeout(&meson_wdt->wdt_dev, timeout, &pdev->dev);
166	watchdog_set_nowayout(&meson_wdt->wdt_dev, nowayout);
167
168	meson_wdt_stop(&meson_wdt->wdt_dev);
169
170	err = watchdog_register_device(&meson_wdt->wdt_dev);
171	if (err)
172		return err;
173
174	platform_set_drvdata(pdev, meson_wdt);
175
176	meson_wdt->restart_handler.notifier_call = meson_restart_handle;
177	meson_wdt->restart_handler.priority = 128;
178	err = register_restart_handler(&meson_wdt->restart_handler);
179	if (err)
180		dev_err(&pdev->dev,
181			"cannot register restart handler (err=%d)\n", err);
182
183	dev_info(&pdev->dev, "Watchdog enabled (timeout=%d sec, nowayout=%d)",
184		 meson_wdt->wdt_dev.timeout, nowayout);
185
186	return 0;
187}
188
189static int meson_wdt_remove(struct platform_device *pdev)
190{
191	struct meson_wdt_dev *meson_wdt = platform_get_drvdata(pdev);
192
193	unregister_restart_handler(&meson_wdt->restart_handler);
194
195	watchdog_unregister_device(&meson_wdt->wdt_dev);
196
197	return 0;
198}
199
200static void meson_wdt_shutdown(struct platform_device *pdev)
201{
202	struct meson_wdt_dev *meson_wdt = platform_get_drvdata(pdev);
203
204	meson_wdt_stop(&meson_wdt->wdt_dev);
205}
206
207static const struct of_device_id meson_wdt_dt_ids[] = {
208	{ .compatible = "amlogic,meson6-wdt" },
209	{ /* sentinel */ }
210};
211MODULE_DEVICE_TABLE(of, meson_wdt_dt_ids);
212
213static struct platform_driver meson_wdt_driver = {
214	.probe		= meson_wdt_probe,
215	.remove		= meson_wdt_remove,
216	.shutdown	= meson_wdt_shutdown,
217	.driver		= {
218		.owner		= THIS_MODULE,
219		.name		= DRV_NAME,
220		.of_match_table	= meson_wdt_dt_ids,
221	},
222};
223
224module_platform_driver(meson_wdt_driver);
225
226module_param(timeout, uint, 0);
227MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
228
229module_param(nowayout, bool, 0);
230MODULE_PARM_DESC(nowayout,
231		 "Watchdog cannot be stopped once started (default="
232		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
233
234MODULE_LICENSE("GPL");
235MODULE_AUTHOR("Carlo Caione <carlo@caione.org>");
236MODULE_DESCRIPTION("Meson Watchdog Timer Driver");
237