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;
 48
 49static bool nowayout = WATCHDOG_NOWAYOUT;
 50module_param(nowayout, bool, 0);
 51MODULE_PARM_DESC(nowayout,
 52		"Watchdog cannot be stopped once started (default="
 53		__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 54
 55static inline void rt_wdt_w32(unsigned reg, u32 val)
 56{
 57	iowrite32(val, rt288x_wdt_base + reg);
 58}
 59
 60static inline u32 rt_wdt_r32(unsigned reg)
 61{
 62	return ioread32(rt288x_wdt_base + reg);
 63}
 64
 65static int rt288x_wdt_ping(struct watchdog_device *w)
 66{
 67	rt_wdt_w32(TIMER_REG_TMR1LOAD, w->timeout * rt288x_wdt_freq);
 68
 69	return 0;
 70}
 71
 72static int rt288x_wdt_start(struct watchdog_device *w)
 73{
 74	u32 t;
 75
 76	t = rt_wdt_r32(TIMER_REG_TMR1CTL);
 77	t &= ~(TMR1CTL_MODE_MASK << TMR1CTL_MODE_SHIFT |
 78		TMR1CTL_PRESCALE_MASK);
 79	t |= (TMR1CTL_MODE_WDT << TMR1CTL_MODE_SHIFT |
 80		TMR1CTL_PRESCALE_65536);
 81	rt_wdt_w32(TIMER_REG_TMR1CTL, t);
 82
 83	rt288x_wdt_ping(w);
 84
 85	t = rt_wdt_r32(TIMER_REG_TMR1CTL);
 86	t |= TMR1CTL_ENABLE;
 87	rt_wdt_w32(TIMER_REG_TMR1CTL, t);
 88
 89	return 0;
 90}
 91
 92static int rt288x_wdt_stop(struct watchdog_device *w)
 93{
 94	u32 t;
 95
 96	rt288x_wdt_ping(w);
 97
 98	t = rt_wdt_r32(TIMER_REG_TMR1CTL);
 99	t &= ~TMR1CTL_ENABLE;
100	rt_wdt_w32(TIMER_REG_TMR1CTL, t);
101
102	return 0;
103}
104
105static int rt288x_wdt_set_timeout(struct watchdog_device *w, unsigned int t)
106{
107	w->timeout = t;
108	rt288x_wdt_ping(w);
109
110	return 0;
111}
112
113static int rt288x_wdt_bootcause(void)
114{
115	if (rt_sysc_r32(SYSC_RSTSTAT) & WDT_RST_CAUSE)
116		return WDIOF_CARDRESET;
117
118	return 0;
119}
120
121static struct watchdog_info rt288x_wdt_info = {
122	.identity = "Ralink Watchdog",
123	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
124};
125
126static struct watchdog_ops rt288x_wdt_ops = {
127	.owner = THIS_MODULE,
128	.start = rt288x_wdt_start,
129	.stop = rt288x_wdt_stop,
130	.ping = rt288x_wdt_ping,
131	.set_timeout = rt288x_wdt_set_timeout,
132};
133
134static struct watchdog_device rt288x_wdt_dev = {
135	.info = &rt288x_wdt_info,
136	.ops = &rt288x_wdt_ops,
137	.min_timeout = 1,
138};
139
140static int rt288x_wdt_probe(struct platform_device *pdev)
141{
142	struct resource *res;
143	int ret;
144
145	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
146	rt288x_wdt_base = devm_ioremap_resource(&pdev->dev, res);
147	if (IS_ERR(rt288x_wdt_base))
148		return PTR_ERR(rt288x_wdt_base);
149
150	rt288x_wdt_clk = devm_clk_get(&pdev->dev, NULL);
151	if (IS_ERR(rt288x_wdt_clk))
152		return PTR_ERR(rt288x_wdt_clk);
153
154	device_reset(&pdev->dev);
155
156	rt288x_wdt_freq = clk_get_rate(rt288x_wdt_clk) / RALINK_WDT_PRESCALE;
157
158	rt288x_wdt_dev.dev = &pdev->dev;
159	rt288x_wdt_dev.bootstatus = rt288x_wdt_bootcause();
160
161	rt288x_wdt_dev.max_timeout = (0xfffful / rt288x_wdt_freq);
162	rt288x_wdt_dev.timeout = rt288x_wdt_dev.max_timeout;
163
164	watchdog_set_nowayout(&rt288x_wdt_dev, nowayout);
165
166	ret = watchdog_register_device(&rt288x_wdt_dev);
167	if (!ret)
168		dev_info(&pdev->dev, "Initialized\n");
169
170	return 0;
171}
172
173static int rt288x_wdt_remove(struct platform_device *pdev)
174{
175	watchdog_unregister_device(&rt288x_wdt_dev);
176
177	return 0;
178}
179
180static void rt288x_wdt_shutdown(struct platform_device *pdev)
181{
182	rt288x_wdt_stop(&rt288x_wdt_dev);
183}
184
185static const struct of_device_id rt288x_wdt_match[] = {
186	{ .compatible = "ralink,rt2880-wdt" },
187	{},
188};
189MODULE_DEVICE_TABLE(of, rt288x_wdt_match);
190
191static struct platform_driver rt288x_wdt_driver = {
192	.probe		= rt288x_wdt_probe,
193	.remove		= rt288x_wdt_remove,
194	.shutdown	= rt288x_wdt_shutdown,
195	.driver		= {
196		.name		= KBUILD_MODNAME,
197		.owner		= THIS_MODULE,
198		.of_match_table	= rt288x_wdt_match,
199	},
200};
201
202module_platform_driver(rt288x_wdt_driver);
203
204MODULE_DESCRIPTION("MediaTek/Ralink RT288x/RT3xxx hardware watchdog driver");
205MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org");
206MODULE_LICENSE("GPL v2");