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/watchdog.h>
17#include <linux/init.h>
18#include <linux/platform_device.h>
19#include <linux/clk.h>
20#include <linux/err.h>
21#include <linux/io.h>
22#include <asm/txx9tmr.h>
23
24#define WD_TIMER_CCD	7		/* 1/256 */
25#define WD_TIMER_CLK	(clk_get_rate(txx9_imclk) / (2 << WD_TIMER_CCD))
26#define WD_MAX_TIMEOUT	((0xffffffff >> (32 - TXX9_TIMER_BITS)) / WD_TIMER_CLK)
27#define TIMER_MARGIN	60		/* Default is 60 seconds */
28
29static unsigned int timeout = TIMER_MARGIN;	/* in seconds */
30module_param(timeout, uint, 0);
31MODULE_PARM_DESC(timeout,
32	"Watchdog timeout in seconds. "
33	"(0<timeout<((2^" __MODULE_STRING(TXX9_TIMER_BITS) ")/(IMCLK/256)), "
34	"default=" __MODULE_STRING(TIMER_MARGIN) ")");
35
36static bool nowayout = WATCHDOG_NOWAYOUT;
37module_param(nowayout, bool, 0);
38MODULE_PARM_DESC(nowayout,
39	"Watchdog cannot be stopped once started "
40	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
41
42static struct txx9_tmr_reg __iomem *txx9wdt_reg;
43static struct clk *txx9_imclk;
44static DEFINE_SPINLOCK(txx9_lock);
45
46static int txx9wdt_ping(struct watchdog_device *wdt_dev)
47{
48	spin_lock(&txx9_lock);
49	__raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
50	spin_unlock(&txx9_lock);
51	return 0;
52}
53
54static int txx9wdt_start(struct watchdog_device *wdt_dev)
55{
56	spin_lock(&txx9_lock);
57	__raw_writel(WD_TIMER_CLK * wdt_dev->timeout, &txx9wdt_reg->cpra);
58	__raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr);
59	__raw_writel(0, &txx9wdt_reg->tisr);	/* clear pending interrupt */
60	__raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG,
61		     &txx9wdt_reg->tcr);
62	__raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
63	spin_unlock(&txx9_lock);
64	return 0;
65}
66
67static int txx9wdt_stop(struct watchdog_device *wdt_dev)
68{
69	spin_lock(&txx9_lock);
70	__raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr);
71	__raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE,
72		     &txx9wdt_reg->tcr);
73	spin_unlock(&txx9_lock);
74	return 0;
75}
76
77static int txx9wdt_set_timeout(struct watchdog_device *wdt_dev,
78			       unsigned int new_timeout)
79{
80	wdt_dev->timeout = new_timeout;
81	txx9wdt_stop(wdt_dev);
82	txx9wdt_start(wdt_dev);
83	return 0;
84}
85
86static const struct watchdog_info txx9wdt_info = {
87	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
88	.identity = "Hardware Watchdog for TXx9",
89};
90
91static const struct watchdog_ops txx9wdt_ops = {
92	.owner = THIS_MODULE,
93	.start = txx9wdt_start,
94	.stop = txx9wdt_stop,
95	.ping = txx9wdt_ping,
96	.set_timeout = txx9wdt_set_timeout,
97};
98
99static struct watchdog_device txx9wdt = {
100	.info = &txx9wdt_info,
101	.ops = &txx9wdt_ops,
102};
103
104static int __init txx9wdt_probe(struct platform_device *dev)
105{
106	struct resource *res;
107	int ret;
108
109	txx9_imclk = clk_get(NULL, "imbus_clk");
110	if (IS_ERR(txx9_imclk)) {
111		ret = PTR_ERR(txx9_imclk);
112		txx9_imclk = NULL;
113		goto exit;
114	}
115	ret = clk_enable(txx9_imclk);
116	if (ret) {
117		clk_put(txx9_imclk);
118		txx9_imclk = NULL;
119		goto exit;
120	}
121
122	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
123	txx9wdt_reg = devm_ioremap_resource(&dev->dev, res);
124	if (IS_ERR(txx9wdt_reg)) {
125		ret = PTR_ERR(txx9wdt_reg);
126		goto exit;
127	}
128
129	if (timeout < 1 || timeout > WD_MAX_TIMEOUT)
130		timeout = TIMER_MARGIN;
131	txx9wdt.timeout = timeout;
132	txx9wdt.min_timeout = 1;
133	txx9wdt.max_timeout = WD_MAX_TIMEOUT;
134	watchdog_set_nowayout(&txx9wdt, nowayout);
135
136	ret = watchdog_register_device(&txx9wdt);
137	if (ret)
138		goto exit;
139
140	pr_info("Hardware Watchdog Timer: timeout=%d sec (max %ld) (nowayout= %d)\n",
141		timeout, WD_MAX_TIMEOUT, nowayout);
142
143	return 0;
144exit:
145	if (txx9_imclk) {
146		clk_disable(txx9_imclk);
147		clk_put(txx9_imclk);
148	}
149	return ret;
150}
151
152static int __exit txx9wdt_remove(struct platform_device *dev)
153{
154	watchdog_unregister_device(&txx9wdt);
155	clk_disable(txx9_imclk);
156	clk_put(txx9_imclk);
157	return 0;
158}
159
160static void txx9wdt_shutdown(struct platform_device *dev)
161{
162	txx9wdt_stop(&txx9wdt);
163}
164
165static struct platform_driver txx9wdt_driver = {
166	.remove = __exit_p(txx9wdt_remove),
167	.shutdown = txx9wdt_shutdown,
168	.driver = {
169		.name = "txx9wdt",
170	},
171};
172
173module_platform_driver_probe(txx9wdt_driver, txx9wdt_probe);
174
175MODULE_DESCRIPTION("TXx9 Watchdog Driver");
176MODULE_LICENSE("GPL");
177MODULE_ALIAS("platform:txx9wdt");
178