1/*
2 * Ralink RT288x/RT3xxx/MT76xx built-in hardware watchdog timer
3 *
4 * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
5 * Copyright (C) 2013 John Crispin <blogic@openwrt.org>
6 *
7 * This driver was based on: drivers/watchdog/softdog.c
8 *
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License version 2 as published
11 * by the Free Software Foundation.
12 */
13
14#include <linux/clk.h>
15#include <linux/reset.h>
16#include <linux/module.h>
17#include <linux/kernel.h>
18#include <linux/watchdog.h>
19#include <linux/moduleparam.h>
20#include <linux/platform_device.h>
21
22#include <asm/mach-ralink/ralink_regs.h>
23
24#define SYSC_RSTSTAT			0x38
25#define WDT_RST_CAUSE			BIT(1)
26
27#define RALINK_WDT_TIMEOUT		30
28#define RALINK_WDT_PRESCALE		65536
29
30#define TIMER_REG_TMR1LOAD		0x00
31#define TIMER_REG_TMR1CTL		0x08
32
33#define TMRSTAT_TMR1RST			BIT(5)
34
35#define TMR1CTL_ENABLE			BIT(7)
36#define TMR1CTL_MODE_SHIFT		4
37#define TMR1CTL_MODE_MASK		0x3
38#define TMR1CTL_MODE_FREE_RUNNING	0x0
39#define TMR1CTL_MODE_PERIODIC		0x1
40#define TMR1CTL_MODE_TIMEOUT		0x2
41#define TMR1CTL_MODE_WDT		0x3
42#define TMR1CTL_PRESCALE_MASK		0xf
43#define TMR1CTL_PRESCALE_65536		0xf
44
45static struct clk *rt288x_wdt_clk;
46static unsigned long rt288x_wdt_freq;
47static void __iomem *rt288x_wdt_base;
48static struct reset_control *rt288x_wdt_reset;
49
50static bool nowayout = WATCHDOG_NOWAYOUT;
51module_param(nowayout, bool, 0);
52MODULE_PARM_DESC(nowayout,
53		"Watchdog cannot be stopped once started (default="
54		__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
55
56static inline void rt_wdt_w32(unsigned reg, u32 val)
57{
58	iowrite32(val, rt288x_wdt_base + reg);
59}
60
61static inline u32 rt_wdt_r32(unsigned reg)
62{
63	return ioread32(rt288x_wdt_base + reg);
64}
65
66static int rt288x_wdt_ping(struct watchdog_device *w)
67{
68	rt_wdt_w32(TIMER_REG_TMR1LOAD, w->timeout * rt288x_wdt_freq);
69
70	return 0;
71}
72
73static int rt288x_wdt_start(struct watchdog_device *w)
74{
75	u32 t;
76
77	t = rt_wdt_r32(TIMER_REG_TMR1CTL);
78	t &= ~(TMR1CTL_MODE_MASK << TMR1CTL_MODE_SHIFT |
79		TMR1CTL_PRESCALE_MASK);
80	t |= (TMR1CTL_MODE_WDT << TMR1CTL_MODE_SHIFT |
81		TMR1CTL_PRESCALE_65536);
82	rt_wdt_w32(TIMER_REG_TMR1CTL, t);
83
84	rt288x_wdt_ping(w);
85
86	t = rt_wdt_r32(TIMER_REG_TMR1CTL);
87	t |= TMR1CTL_ENABLE;
88	rt_wdt_w32(TIMER_REG_TMR1CTL, t);
89
90	return 0;
91}
92
93static int rt288x_wdt_stop(struct watchdog_device *w)
94{
95	u32 t;
96
97	rt288x_wdt_ping(w);
98
99	t = rt_wdt_r32(TIMER_REG_TMR1CTL);
100	t &= ~TMR1CTL_ENABLE;
101	rt_wdt_w32(TIMER_REG_TMR1CTL, t);
102
103	return 0;
104}
105
106static int rt288x_wdt_set_timeout(struct watchdog_device *w, unsigned int t)
107{
108	w->timeout = t;
109	rt288x_wdt_ping(w);
110
111	return 0;
112}
113
114static int rt288x_wdt_bootcause(void)
115{
116	if (rt_sysc_r32(SYSC_RSTSTAT) & WDT_RST_CAUSE)
117		return WDIOF_CARDRESET;
118
119	return 0;
120}
121
122static struct watchdog_info rt288x_wdt_info = {
123	.identity = "Ralink Watchdog",
124	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
125};
126
127static struct watchdog_ops rt288x_wdt_ops = {
128	.owner = THIS_MODULE,
129	.start = rt288x_wdt_start,
130	.stop = rt288x_wdt_stop,
131	.ping = rt288x_wdt_ping,
132	.set_timeout = rt288x_wdt_set_timeout,
133};
134
135static struct watchdog_device rt288x_wdt_dev = {
136	.info = &rt288x_wdt_info,
137	.ops = &rt288x_wdt_ops,
138	.min_timeout = 1,
139};
140
141static int rt288x_wdt_probe(struct platform_device *pdev)
142{
143	struct resource *res;
144	int ret;
145
146	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
147	rt288x_wdt_base = devm_ioremap_resource(&pdev->dev, res);
148	if (IS_ERR(rt288x_wdt_base))
149		return PTR_ERR(rt288x_wdt_base);
150
151	rt288x_wdt_clk = devm_clk_get(&pdev->dev, NULL);
152	if (IS_ERR(rt288x_wdt_clk))
153		return PTR_ERR(rt288x_wdt_clk);
154
155	rt288x_wdt_reset = devm_reset_control_get(&pdev->dev, NULL);
156	if (!IS_ERR(rt288x_wdt_reset))
157		reset_control_deassert(rt288x_wdt_reset);
158
159	rt288x_wdt_freq = clk_get_rate(rt288x_wdt_clk) / RALINK_WDT_PRESCALE;
160
161	rt288x_wdt_dev.dev = &pdev->dev;
162	rt288x_wdt_dev.bootstatus = rt288x_wdt_bootcause();
163	rt288x_wdt_dev.max_timeout = (0xfffful / rt288x_wdt_freq);
164
165	watchdog_init_timeout(&rt288x_wdt_dev, rt288x_wdt_dev.max_timeout,
166			      &pdev->dev);
167	watchdog_set_nowayout(&rt288x_wdt_dev, nowayout);
168
169	ret = watchdog_register_device(&rt288x_wdt_dev);
170	if (!ret)
171		dev_info(&pdev->dev, "Initialized\n");
172
173	return 0;
174}
175
176static int rt288x_wdt_remove(struct platform_device *pdev)
177{
178	watchdog_unregister_device(&rt288x_wdt_dev);
179
180	return 0;
181}
182
183static void rt288x_wdt_shutdown(struct platform_device *pdev)
184{
185	rt288x_wdt_stop(&rt288x_wdt_dev);
186}
187
188static const struct of_device_id rt288x_wdt_match[] = {
189	{ .compatible = "ralink,rt2880-wdt" },
190	{},
191};
192MODULE_DEVICE_TABLE(of, rt288x_wdt_match);
193
194static struct platform_driver rt288x_wdt_driver = {
195	.probe		= rt288x_wdt_probe,
196	.remove		= rt288x_wdt_remove,
197	.shutdown	= rt288x_wdt_shutdown,
198	.driver		= {
199		.name		= KBUILD_MODNAME,
200		.of_match_table	= rt288x_wdt_match,
201	},
202};
203
204module_platform_driver(rt288x_wdt_driver);
205
206MODULE_DESCRIPTION("MediaTek/Ralink RT288x/RT3xxx hardware watchdog driver");
207MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org");
208MODULE_LICENSE("GPL v2");
209