1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *      Meson Watchdog Driver
4 *
5 *      Copyright (c) 2014 Carlo Caione
6 */
7
8#include <linux/clk.h>
9#include <linux/delay.h>
10#include <linux/err.h>
11#include <linux/init.h>
12#include <linux/io.h>
13#include <linux/kernel.h>
14#include <linux/mod_devicetable.h>
15#include <linux/module.h>
16#include <linux/moduleparam.h>
17#include <linux/platform_device.h>
18#include <linux/property.h>
19#include <linux/types.h>
20#include <linux/watchdog.h>
21
22#define DRV_NAME		"meson_wdt"
23
24#define MESON_WDT_TC		0x00
25#define MESON_WDT_DC_RESET	(3 << 24)
26
27#define MESON_WDT_RESET		0x04
28
29#define MESON_WDT_TIMEOUT	30
30#define MESON_WDT_MIN_TIMEOUT	1
31
32#define MESON_SEC_TO_TC(s, c)	((s) * (c))
33
34static bool nowayout = WATCHDOG_NOWAYOUT;
35static unsigned int timeout;
36
37struct meson_wdt_data {
38	unsigned int enable;
39	unsigned int terminal_count_mask;
40	unsigned int count_unit;
41};
42
43static struct meson_wdt_data meson6_wdt_data = {
44	.enable			= BIT(22),
45	.terminal_count_mask	= 0x3fffff,
46	.count_unit		= 100000, /* 10 us */
47};
48
49static struct meson_wdt_data meson8b_wdt_data = {
50	.enable			= BIT(19),
51	.terminal_count_mask	= 0xffff,
52	.count_unit		= 7812, /* 128 us */
53};
54
55struct meson_wdt_dev {
56	struct watchdog_device wdt_dev;
57	void __iomem *wdt_base;
58	const struct meson_wdt_data *data;
59};
60
61static int meson_wdt_restart(struct watchdog_device *wdt_dev,
62			     unsigned long action, void *data)
63{
64	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
65	u32 tc_reboot = MESON_WDT_DC_RESET;
66
67	tc_reboot |= meson_wdt->data->enable;
68
69	while (1) {
70		writel(tc_reboot, meson_wdt->wdt_base + MESON_WDT_TC);
71		mdelay(5);
72	}
73
74	return 0;
75}
76
77static int meson_wdt_ping(struct watchdog_device *wdt_dev)
78{
79	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
80
81	writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
82
83	return 0;
84}
85
86static void meson_wdt_change_timeout(struct watchdog_device *wdt_dev,
87				     unsigned int timeout)
88{
89	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
90	u32 reg;
91
92	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
93	reg &= ~meson_wdt->data->terminal_count_mask;
94	reg |= MESON_SEC_TO_TC(timeout, meson_wdt->data->count_unit);
95	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
96}
97
98static int meson_wdt_set_timeout(struct watchdog_device *wdt_dev,
99				 unsigned int timeout)
100{
101	wdt_dev->timeout = timeout;
102
103	meson_wdt_change_timeout(wdt_dev, timeout);
104	meson_wdt_ping(wdt_dev);
105
106	return 0;
107}
108
109static int meson_wdt_stop(struct watchdog_device *wdt_dev)
110{
111	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
112	u32 reg;
113
114	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
115	reg &= ~meson_wdt->data->enable;
116	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
117
118	return 0;
119}
120
121static int meson_wdt_start(struct watchdog_device *wdt_dev)
122{
123	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
124	u32 reg;
125
126	meson_wdt_change_timeout(wdt_dev, meson_wdt->wdt_dev.timeout);
127	meson_wdt_ping(wdt_dev);
128
129	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
130	reg |= meson_wdt->data->enable;
131	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
132
133	return 0;
134}
135
136static const struct watchdog_info meson_wdt_info = {
137	.identity	= DRV_NAME,
138	.options	= WDIOF_SETTIMEOUT |
139			  WDIOF_KEEPALIVEPING |
140			  WDIOF_MAGICCLOSE,
141};
142
143static const struct watchdog_ops meson_wdt_ops = {
144	.owner		= THIS_MODULE,
145	.start		= meson_wdt_start,
146	.stop		= meson_wdt_stop,
147	.ping		= meson_wdt_ping,
148	.set_timeout	= meson_wdt_set_timeout,
149	.restart        = meson_wdt_restart,
150};
151
152static const struct of_device_id meson_wdt_dt_ids[] = {
153	{ .compatible = "amlogic,meson6-wdt", .data = &meson6_wdt_data },
154	{ .compatible = "amlogic,meson8-wdt", .data = &meson6_wdt_data },
155	{ .compatible = "amlogic,meson8b-wdt", .data = &meson8b_wdt_data },
156	{ .compatible = "amlogic,meson8m2-wdt", .data = &meson8b_wdt_data },
157	{ /* sentinel */ }
158};
159MODULE_DEVICE_TABLE(of, meson_wdt_dt_ids);
160
161static int meson_wdt_probe(struct platform_device *pdev)
162{
163	struct device *dev = &pdev->dev;
164	struct meson_wdt_dev *meson_wdt;
165	int err;
166
167	meson_wdt = devm_kzalloc(dev, sizeof(*meson_wdt), GFP_KERNEL);
168	if (!meson_wdt)
169		return -ENOMEM;
170
171	meson_wdt->wdt_base = devm_platform_ioremap_resource(pdev, 0);
172	if (IS_ERR(meson_wdt->wdt_base))
173		return PTR_ERR(meson_wdt->wdt_base);
174
175	meson_wdt->data = device_get_match_data(dev);
176
177	meson_wdt->wdt_dev.parent = dev;
178	meson_wdt->wdt_dev.info = &meson_wdt_info;
179	meson_wdt->wdt_dev.ops = &meson_wdt_ops;
180	meson_wdt->wdt_dev.max_timeout =
181		meson_wdt->data->terminal_count_mask / meson_wdt->data->count_unit;
182	meson_wdt->wdt_dev.min_timeout = MESON_WDT_MIN_TIMEOUT;
183	meson_wdt->wdt_dev.timeout = min_t(unsigned int,
184					   MESON_WDT_TIMEOUT,
185					   meson_wdt->wdt_dev.max_timeout);
186
187	watchdog_set_drvdata(&meson_wdt->wdt_dev, meson_wdt);
188
189	watchdog_init_timeout(&meson_wdt->wdt_dev, timeout, dev);
190	watchdog_set_nowayout(&meson_wdt->wdt_dev, nowayout);
191	watchdog_set_restart_priority(&meson_wdt->wdt_dev, 128);
192
193	meson_wdt_stop(&meson_wdt->wdt_dev);
194
195	watchdog_stop_on_reboot(&meson_wdt->wdt_dev);
196	err = devm_watchdog_register_device(dev, &meson_wdt->wdt_dev);
197	if (err)
198		return err;
199
200	dev_info(dev, "Watchdog enabled (timeout=%d sec, nowayout=%d)",
201		 meson_wdt->wdt_dev.timeout, nowayout);
202
203	return 0;
204}
205
206static struct platform_driver meson_wdt_driver = {
207	.probe		= meson_wdt_probe,
208	.driver		= {
209		.name		= DRV_NAME,
210		.of_match_table	= meson_wdt_dt_ids,
211	},
212};
213
214module_platform_driver(meson_wdt_driver);
215
216module_param(timeout, uint, 0);
217MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
218
219module_param(nowayout, bool, 0);
220MODULE_PARM_DESC(nowayout,
221		 "Watchdog cannot be stopped once started (default="
222		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
223
224MODULE_LICENSE("GPL");
225MODULE_AUTHOR("Carlo Caione <carlo@caione.org>");
226MODULE_DESCRIPTION("Meson Watchdog Timer Driver");
227