1/*
2 * Mediatek Watchdog Driver
3 *
4 * Copyright (C) 2014 Matthias Brugger
5 *
6 * Matthias Brugger <matthias.bgg@gmail.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16 * GNU General Public License for more details.
17 *
18 * Based on sunxi_wdt.c
19 */
20
21#include <linux/err.h>
22#include <linux/init.h>
23#include <linux/io.h>
24#include <linux/kernel.h>
25#include <linux/module.h>
26#include <linux/moduleparam.h>
27#include <linux/of.h>
28#include <linux/platform_device.h>
29#include <linux/types.h>
30#include <linux/watchdog.h>
31#include <linux/notifier.h>
32#include <linux/reboot.h>
33#include <linux/delay.h>
34
35#define WDT_MAX_TIMEOUT		31
36#define WDT_MIN_TIMEOUT		1
37#define WDT_LENGTH_TIMEOUT(n)	((n) << 5)
38
39#define WDT_LENGTH		0x04
40#define WDT_LENGTH_KEY		0x8
41
42#define WDT_RST			0x08
43#define WDT_RST_RELOAD		0x1971
44
45#define WDT_MODE		0x00
46#define WDT_MODE_EN		(1 << 0)
47#define WDT_MODE_EXT_POL_LOW	(0 << 1)
48#define WDT_MODE_EXT_POL_HIGH	(1 << 1)
49#define WDT_MODE_EXRST_EN	(1 << 2)
50#define WDT_MODE_IRQ_EN		(1 << 3)
51#define WDT_MODE_AUTO_START	(1 << 4)
52#define WDT_MODE_DUAL_EN	(1 << 6)
53#define WDT_MODE_KEY		0x22000000
54
55#define WDT_SWRST		0x14
56#define WDT_SWRST_KEY		0x1209
57
58#define DRV_NAME		"mtk-wdt"
59#define DRV_VERSION		"1.0"
60
61static bool nowayout = WATCHDOG_NOWAYOUT;
62static unsigned int timeout = WDT_MAX_TIMEOUT;
63
64struct mtk_wdt_dev {
65	struct watchdog_device wdt_dev;
66	void __iomem *wdt_base;
67	struct notifier_block restart_handler;
68};
69
70static int mtk_reset_handler(struct notifier_block *this, unsigned long mode,
71				void *cmd)
72{
73	struct mtk_wdt_dev *mtk_wdt;
74	void __iomem *wdt_base;
75
76	mtk_wdt = container_of(this, struct mtk_wdt_dev, restart_handler);
77	wdt_base = mtk_wdt->wdt_base;
78
79	while (1) {
80		writel(WDT_SWRST_KEY, wdt_base + WDT_SWRST);
81		mdelay(5);
82	}
83
84	return NOTIFY_DONE;
85}
86
87static int mtk_wdt_ping(struct watchdog_device *wdt_dev)
88{
89	struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
90	void __iomem *wdt_base = mtk_wdt->wdt_base;
91
92	iowrite32(WDT_RST_RELOAD, wdt_base + WDT_RST);
93
94	return 0;
95}
96
97static int mtk_wdt_set_timeout(struct watchdog_device *wdt_dev,
98				unsigned int timeout)
99{
100	struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
101	void __iomem *wdt_base = mtk_wdt->wdt_base;
102	u32 reg;
103
104	wdt_dev->timeout = timeout;
105
106	/*
107	 * One bit is the value of 512 ticks
108	 * The clock has 32 KHz
109	 */
110	reg = WDT_LENGTH_TIMEOUT(timeout << 6) | WDT_LENGTH_KEY;
111	iowrite32(reg, wdt_base + WDT_LENGTH);
112
113	mtk_wdt_ping(wdt_dev);
114
115	return 0;
116}
117
118static int mtk_wdt_stop(struct watchdog_device *wdt_dev)
119{
120	struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
121	void __iomem *wdt_base = mtk_wdt->wdt_base;
122	u32 reg;
123
124	reg = readl(wdt_base + WDT_MODE);
125	reg &= ~WDT_MODE_EN;
126	iowrite32(reg, wdt_base + WDT_MODE);
127
128	return 0;
129}
130
131static int mtk_wdt_start(struct watchdog_device *wdt_dev)
132{
133	u32 reg;
134	struct mtk_wdt_dev *mtk_wdt = watchdog_get_drvdata(wdt_dev);
135	void __iomem *wdt_base = mtk_wdt->wdt_base;
136	int ret;
137
138	ret = mtk_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
139	if (ret < 0)
140		return ret;
141
142	reg = ioread32(wdt_base + WDT_MODE);
143	reg &= ~(WDT_MODE_IRQ_EN | WDT_MODE_DUAL_EN);
144	reg |= (WDT_MODE_EN | WDT_MODE_KEY);
145	iowrite32(reg, wdt_base + WDT_MODE);
146
147	return 0;
148}
149
150static const struct watchdog_info mtk_wdt_info = {
151	.identity	= DRV_NAME,
152	.options	= WDIOF_SETTIMEOUT |
153			  WDIOF_KEEPALIVEPING |
154			  WDIOF_MAGICCLOSE,
155};
156
157static const struct watchdog_ops mtk_wdt_ops = {
158	.owner		= THIS_MODULE,
159	.start		= mtk_wdt_start,
160	.stop		= mtk_wdt_stop,
161	.ping		= mtk_wdt_ping,
162	.set_timeout	= mtk_wdt_set_timeout,
163};
164
165static int mtk_wdt_probe(struct platform_device *pdev)
166{
167	struct mtk_wdt_dev *mtk_wdt;
168	struct resource *res;
169	int err;
170
171	mtk_wdt = devm_kzalloc(&pdev->dev, sizeof(*mtk_wdt), GFP_KERNEL);
172	if (!mtk_wdt)
173		return -ENOMEM;
174
175	platform_set_drvdata(pdev, mtk_wdt);
176
177	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
178	mtk_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
179	if (IS_ERR(mtk_wdt->wdt_base))
180		return PTR_ERR(mtk_wdt->wdt_base);
181
182	mtk_wdt->wdt_dev.info = &mtk_wdt_info;
183	mtk_wdt->wdt_dev.ops = &mtk_wdt_ops;
184	mtk_wdt->wdt_dev.timeout = WDT_MAX_TIMEOUT;
185	mtk_wdt->wdt_dev.max_timeout = WDT_MAX_TIMEOUT;
186	mtk_wdt->wdt_dev.min_timeout = WDT_MIN_TIMEOUT;
187	mtk_wdt->wdt_dev.parent = &pdev->dev;
188
189	watchdog_init_timeout(&mtk_wdt->wdt_dev, timeout, &pdev->dev);
190	watchdog_set_nowayout(&mtk_wdt->wdt_dev, nowayout);
191
192	watchdog_set_drvdata(&mtk_wdt->wdt_dev, mtk_wdt);
193
194	mtk_wdt_stop(&mtk_wdt->wdt_dev);
195
196	err = watchdog_register_device(&mtk_wdt->wdt_dev);
197	if (unlikely(err))
198		return err;
199
200	mtk_wdt->restart_handler.notifier_call = mtk_reset_handler;
201	mtk_wdt->restart_handler.priority = 128;
202	err = register_restart_handler(&mtk_wdt->restart_handler);
203	if (err)
204		dev_warn(&pdev->dev,
205			"cannot register restart handler (err=%d)\n", err);
206
207	dev_info(&pdev->dev, "Watchdog enabled (timeout=%d sec, nowayout=%d)\n",
208			mtk_wdt->wdt_dev.timeout, nowayout);
209
210	return 0;
211}
212
213static int mtk_wdt_remove(struct platform_device *pdev)
214{
215	struct mtk_wdt_dev *mtk_wdt = platform_get_drvdata(pdev);
216
217	unregister_restart_handler(&mtk_wdt->restart_handler);
218
219	watchdog_unregister_device(&mtk_wdt->wdt_dev);
220
221	return 0;
222}
223
224static const struct of_device_id mtk_wdt_dt_ids[] = {
225	{ .compatible = "mediatek,mt6589-wdt" },
226	{ /* sentinel */ }
227};
228MODULE_DEVICE_TABLE(of, mtk_wdt_dt_ids);
229
230static struct platform_driver mtk_wdt_driver = {
231	.probe		= mtk_wdt_probe,
232	.remove		= mtk_wdt_remove,
233	.driver		= {
234		.name		= DRV_NAME,
235		.of_match_table	= mtk_wdt_dt_ids,
236	},
237};
238
239module_platform_driver(mtk_wdt_driver);
240
241module_param(timeout, uint, 0);
242MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
243
244module_param(nowayout, bool, 0);
245MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
246			__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
247
248MODULE_LICENSE("GPL");
249MODULE_AUTHOR("Matthias Brugger <matthias.bgg@gmail.com>");
250MODULE_DESCRIPTION("Mediatek WatchDog Timer Driver");
251MODULE_VERSION(DRV_VERSION);
252