1/*
2 * txx9wdt: A Hardware Watchdog Driver for TXx9 SoCs
3 *
4 * Copyright (C) 2007 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13#include <linux/module.h>
14#include <linux/moduleparam.h>
15#include <linux/types.h>
16#include <linux/miscdevice.h>
17#include <linux/watchdog.h>
18#include <linux/init.h>
19#include <linux/platform_device.h>
20#include <linux/clk.h>
21#include <linux/err.h>
22#include <linux/io.h>
23#include <asm/txx9tmr.h>
24
25#define WD_TIMER_CCD	7		/* 1/256 */
26#define WD_TIMER_CLK	(clk_get_rate(txx9_imclk) / (2 << WD_TIMER_CCD))
27#define WD_MAX_TIMEOUT	((0xffffffff >> (32 - TXX9_TIMER_BITS)) / WD_TIMER_CLK)
28#define TIMER_MARGIN	60		/* Default is 60 seconds */
29
30static unsigned int timeout = TIMER_MARGIN;	/* in seconds */
31module_param(timeout, uint, 0);
32MODULE_PARM_DESC(timeout,
33	"Watchdog timeout in seconds. "
34	"(0<timeout<((2^" __MODULE_STRING(TXX9_TIMER_BITS) ")/(IMCLK/256)), "
35	"default=" __MODULE_STRING(TIMER_MARGIN) ")");
36
37static bool nowayout = WATCHDOG_NOWAYOUT;
38module_param(nowayout, bool, 0);
39MODULE_PARM_DESC(nowayout,
40	"Watchdog cannot be stopped once started "
41	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
42
43static struct txx9_tmr_reg __iomem *txx9wdt_reg;
44static struct clk *txx9_imclk;
45static DEFINE_SPINLOCK(txx9_lock);
46
47static int txx9wdt_ping(struct watchdog_device *wdt_dev)
48{
49	spin_lock(&txx9_lock);
50	__raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
51	spin_unlock(&txx9_lock);
52	return 0;
53}
54
55static int txx9wdt_start(struct watchdog_device *wdt_dev)
56{
57	spin_lock(&txx9_lock);
58	__raw_writel(WD_TIMER_CLK * wdt_dev->timeout, &txx9wdt_reg->cpra);
59	__raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr);
60	__raw_writel(0, &txx9wdt_reg->tisr);	/* clear pending interrupt */
61	__raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG,
62		     &txx9wdt_reg->tcr);
63	__raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
64	spin_unlock(&txx9_lock);
65	return 0;
66}
67
68static int txx9wdt_stop(struct watchdog_device *wdt_dev)
69{
70	spin_lock(&txx9_lock);
71	__raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr);
72	__raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE,
73		     &txx9wdt_reg->tcr);
74	spin_unlock(&txx9_lock);
75	return 0;
76}
77
78static int txx9wdt_set_timeout(struct watchdog_device *wdt_dev,
79			       unsigned int new_timeout)
80{
81	wdt_dev->timeout = new_timeout;
82	txx9wdt_stop(wdt_dev);
83	txx9wdt_start(wdt_dev);
84	return 0;
85}
86
87static const struct watchdog_info txx9wdt_info = {
88	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
89	.identity = "Hardware Watchdog for TXx9",
90};
91
92static const struct watchdog_ops txx9wdt_ops = {
93	.owner = THIS_MODULE,
94	.start = txx9wdt_start,
95	.stop = txx9wdt_stop,
96	.ping = txx9wdt_ping,
97	.set_timeout = txx9wdt_set_timeout,
98};
99
100static struct watchdog_device txx9wdt = {
101	.info = &txx9wdt_info,
102	.ops = &txx9wdt_ops,
103};
104
105static int __init txx9wdt_probe(struct platform_device *dev)
106{
107	struct resource *res;
108	int ret;
109
110	txx9_imclk = clk_get(NULL, "imbus_clk");
111	if (IS_ERR(txx9_imclk)) {
112		ret = PTR_ERR(txx9_imclk);
113		txx9_imclk = NULL;
114		goto exit;
115	}
116	ret = clk_enable(txx9_imclk);
117	if (ret) {
118		clk_put(txx9_imclk);
119		txx9_imclk = NULL;
120		goto exit;
121	}
122
123	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
124	txx9wdt_reg = devm_request_and_ioremap(&dev->dev, res);
125	if (!txx9wdt_reg) {
126		ret = -EBUSY;
127		goto exit;
128	}
129
130	if (timeout < 1 || timeout > WD_MAX_TIMEOUT)
131		timeout = TIMER_MARGIN;
132	txx9wdt.timeout = timeout;
133	txx9wdt.min_timeout = 1;
134	txx9wdt.max_timeout = WD_MAX_TIMEOUT;
135	watchdog_set_nowayout(&txx9wdt, nowayout);
136
137	ret = watchdog_register_device(&txx9wdt);
138	if (ret)
139		goto exit;
140
141	pr_info("Hardware Watchdog Timer: timeout=%d sec (max %ld) (nowayout= %d)\n",
142		timeout, WD_MAX_TIMEOUT, nowayout);
143
144	return 0;
145exit:
146	if (txx9_imclk) {
147		clk_disable(txx9_imclk);
148		clk_put(txx9_imclk);
149	}
150	return ret;
151}
152
153static int __exit txx9wdt_remove(struct platform_device *dev)
154{
155	watchdog_unregister_device(&txx9wdt);
156	clk_disable(txx9_imclk);
157	clk_put(txx9_imclk);
158	return 0;
159}
160
161static void txx9wdt_shutdown(struct platform_device *dev)
162{
163	txx9wdt_stop(&txx9wdt);
164}
165
166static struct platform_driver txx9wdt_driver = {
167	.remove = __exit_p(txx9wdt_remove),
168	.shutdown = txx9wdt_shutdown,
169	.driver = {
170		.name = "txx9wdt",
171		.owner = THIS_MODULE,
172	},
173};
174
175static int __init watchdog_init(void)
176{
177	return platform_driver_probe(&txx9wdt_driver, txx9wdt_probe);
178}
179
180static void __exit watchdog_exit(void)
181{
182	platform_driver_unregister(&txx9wdt_driver);
183}
184
185module_init(watchdog_init);
186module_exit(watchdog_exit);
187
188MODULE_DESCRIPTION("TXx9 Watchdog Driver");
189MODULE_LICENSE("GPL");
190MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
191MODULE_ALIAS("platform:txx9wdt");
192