1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Ralink MT7621/MT7628 built-in hardware watchdog timer
4 *
5 * Copyright (C) 2014 John Crispin <john@phrozen.org>
6 *
7 * This driver was based on: drivers/watchdog/rt2880_wdt.c
8 */
9
10#include <linux/clk.h>
11#include <linux/reset.h>
12#include <linux/module.h>
13#include <linux/kernel.h>
14#include <linux/watchdog.h>
15#include <linux/moduleparam.h>
16#include <linux/platform_device.h>
17#include <linux/mod_devicetable.h>
18#include <linux/mfd/syscon.h>
19#include <linux/regmap.h>
20
21#define SYSC_RSTSTAT 0x38
22#define WDT_RST_CAUSE BIT(1)
23
24#define RALINK_WDT_TIMEOUT 30
25
26#define TIMER_REG_TMRSTAT 0x00
27#define TIMER_REG_TMR1LOAD 0x24
28#define TIMER_REG_TMR1CTL 0x20
29
30#define TMR1CTL_ENABLE BIT(7)
31#define TMR1CTL_RESTART BIT(9)
32#define TMR1CTL_PRESCALE_SHIFT 16
33
34struct mt7621_wdt_data {
35 void __iomem *base;
36 struct reset_control *rst;
37 struct regmap *sysc;
38 struct watchdog_device wdt;
39};
40
41static bool nowayout = WATCHDOG_NOWAYOUT;
42module_param(nowayout, bool, 0);
43MODULE_PARM_DESC(nowayout,
44 "Watchdog cannot be stopped once started (default="
45 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
46
47static inline void rt_wdt_w32(void __iomem *base, unsigned int reg, u32 val)
48{
49 iowrite32(val, base + reg);
50}
51
52static inline u32 rt_wdt_r32(void __iomem *base, unsigned int reg)
53{
54 return ioread32(base + reg);
55}
56
57static int mt7621_wdt_ping(struct watchdog_device *w)
58{
59 struct mt7621_wdt_data *drvdata = watchdog_get_drvdata(wdd: w);
60
61 rt_wdt_w32(base: drvdata->base, TIMER_REG_TMRSTAT, TMR1CTL_RESTART);
62
63 return 0;
64}
65
66static int mt7621_wdt_set_timeout(struct watchdog_device *w, unsigned int t)
67{
68 struct mt7621_wdt_data *drvdata = watchdog_get_drvdata(wdd: w);
69
70 w->timeout = t;
71 rt_wdt_w32(base: drvdata->base, TIMER_REG_TMR1LOAD, val: t * 1000);
72 mt7621_wdt_ping(w);
73
74 return 0;
75}
76
77static int mt7621_wdt_start(struct watchdog_device *w)
78{
79 struct mt7621_wdt_data *drvdata = watchdog_get_drvdata(wdd: w);
80 u32 t;
81
82 /* set the prescaler to 1ms == 1000us */
83 rt_wdt_w32(base: drvdata->base, TIMER_REG_TMR1CTL, val: 1000 << TMR1CTL_PRESCALE_SHIFT);
84
85 mt7621_wdt_set_timeout(w, t: w->timeout);
86
87 t = rt_wdt_r32(base: drvdata->base, TIMER_REG_TMR1CTL);
88 t |= TMR1CTL_ENABLE;
89 rt_wdt_w32(base: drvdata->base, TIMER_REG_TMR1CTL, val: t);
90
91 return 0;
92}
93
94static int mt7621_wdt_stop(struct watchdog_device *w)
95{
96 struct mt7621_wdt_data *drvdata = watchdog_get_drvdata(wdd: w);
97 u32 t;
98
99 mt7621_wdt_ping(w);
100
101 t = rt_wdt_r32(base: drvdata->base, TIMER_REG_TMR1CTL);
102 t &= ~TMR1CTL_ENABLE;
103 rt_wdt_w32(base: drvdata->base, TIMER_REG_TMR1CTL, val: t);
104
105 return 0;
106}
107
108static int mt7621_wdt_bootcause(struct mt7621_wdt_data *d)
109{
110 u32 val;
111
112 regmap_read(map: d->sysc, SYSC_RSTSTAT, val: &val);
113 if (val & WDT_RST_CAUSE)
114 return WDIOF_CARDRESET;
115
116 return 0;
117}
118
119static int mt7621_wdt_is_running(struct watchdog_device *w)
120{
121 struct mt7621_wdt_data *drvdata = watchdog_get_drvdata(wdd: w);
122
123 return !!(rt_wdt_r32(base: drvdata->base, TIMER_REG_TMR1CTL) & TMR1CTL_ENABLE);
124}
125
126static const struct watchdog_info mt7621_wdt_info = {
127 .identity = "Mediatek Watchdog",
128 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
129};
130
131static const struct watchdog_ops mt7621_wdt_ops = {
132 .owner = THIS_MODULE,
133 .start = mt7621_wdt_start,
134 .stop = mt7621_wdt_stop,
135 .ping = mt7621_wdt_ping,
136 .set_timeout = mt7621_wdt_set_timeout,
137};
138
139static int mt7621_wdt_probe(struct platform_device *pdev)
140{
141 struct device_node *np = pdev->dev.of_node;
142 struct device *dev = &pdev->dev;
143 struct watchdog_device *mt7621_wdt;
144 struct mt7621_wdt_data *drvdata;
145 int err;
146
147 drvdata = devm_kzalloc(dev, size: sizeof(*drvdata), GFP_KERNEL);
148 if (!drvdata)
149 return -ENOMEM;
150
151 drvdata->sysc = syscon_regmap_lookup_by_phandle(np, property: "mediatek,sysctl");
152 if (IS_ERR(ptr: drvdata->sysc)) {
153 drvdata->sysc = syscon_regmap_lookup_by_compatible(s: "mediatek,mt7621-sysc");
154 if (IS_ERR(ptr: drvdata->sysc))
155 return PTR_ERR(ptr: drvdata->sysc);
156 }
157
158 drvdata->base = devm_platform_ioremap_resource(pdev, index: 0);
159 if (IS_ERR(ptr: drvdata->base))
160 return PTR_ERR(ptr: drvdata->base);
161
162 drvdata->rst = devm_reset_control_get_exclusive(dev, NULL);
163 if (!IS_ERR(ptr: drvdata->rst))
164 reset_control_deassert(rstc: drvdata->rst);
165
166 mt7621_wdt = &drvdata->wdt;
167 mt7621_wdt->info = &mt7621_wdt_info;
168 mt7621_wdt->ops = &mt7621_wdt_ops;
169 mt7621_wdt->min_timeout = 1;
170 mt7621_wdt->max_timeout = 0xfffful / 1000;
171 mt7621_wdt->parent = dev;
172
173 mt7621_wdt->bootstatus = mt7621_wdt_bootcause(d: drvdata);
174
175 watchdog_init_timeout(wdd: mt7621_wdt, timeout_parm: mt7621_wdt->max_timeout, dev);
176 watchdog_set_nowayout(wdd: mt7621_wdt, nowayout);
177 watchdog_set_drvdata(wdd: mt7621_wdt, data: drvdata);
178
179 if (mt7621_wdt_is_running(w: mt7621_wdt)) {
180 /*
181 * Make sure to apply timeout from watchdog core, taking
182 * the prescaler of this driver here into account (the
183 * boot loader might be using a different prescaler).
184 *
185 * To avoid spurious resets because of different scaling,
186 * we first disable the watchdog, set the new prescaler
187 * and timeout, and then re-enable the watchdog.
188 */
189 mt7621_wdt_stop(w: mt7621_wdt);
190 mt7621_wdt_start(w: mt7621_wdt);
191 set_bit(WDOG_HW_RUNNING, addr: &mt7621_wdt->status);
192 }
193
194 err = devm_watchdog_register_device(dev, &drvdata->wdt);
195 if (err)
196 return err;
197
198 platform_set_drvdata(pdev, data: drvdata);
199
200 return 0;
201}
202
203static void mt7621_wdt_shutdown(struct platform_device *pdev)
204{
205 struct mt7621_wdt_data *drvdata = platform_get_drvdata(pdev);
206
207 mt7621_wdt_stop(w: &drvdata->wdt);
208}
209
210static const struct of_device_id mt7621_wdt_match[] = {
211 { .compatible = "mediatek,mt7621-wdt" },
212 {},
213};
214MODULE_DEVICE_TABLE(of, mt7621_wdt_match);
215
216static struct platform_driver mt7621_wdt_driver = {
217 .probe = mt7621_wdt_probe,
218 .shutdown = mt7621_wdt_shutdown,
219 .driver = {
220 .name = KBUILD_MODNAME,
221 .of_match_table = mt7621_wdt_match,
222 },
223};
224
225module_platform_driver(mt7621_wdt_driver);
226
227MODULE_DESCRIPTION("MediaTek MT762x hardware watchdog driver");
228MODULE_AUTHOR("John Crispin <john@phrozen.org");
229MODULE_LICENSE("GPL v2");
230

source code of linux/drivers/watchdog/mt7621_wdt.c