1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * txx9wdt: A Hardware Watchdog Driver for TXx9 SoCs
4 *
5 * Copyright (C) 2007 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
6 */
7
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10#include <linux/module.h>
11#include <linux/moduleparam.h>
12#include <linux/types.h>
13#include <linux/watchdog.h>
14#include <linux/init.h>
15#include <linux/platform_device.h>
16#include <linux/clk.h>
17#include <linux/err.h>
18#include <linux/io.h>
19#include <asm/txx9tmr.h>
20
21#define WD_TIMER_CCD	7		/* 1/256 */
22#define WD_TIMER_CLK	(clk_get_rate(txx9_imclk) / (2 << WD_TIMER_CCD))
23#define WD_MAX_TIMEOUT	((0xffffffff >> (32 - TXX9_TIMER_BITS)) / WD_TIMER_CLK)
24#define TIMER_MARGIN	60		/* Default is 60 seconds */
25
26static unsigned int timeout = TIMER_MARGIN;	/* in seconds */
27module_param(timeout, uint, 0);
28MODULE_PARM_DESC(timeout,
29	"Watchdog timeout in seconds. "
30	"(0<timeout<((2^" __MODULE_STRING(TXX9_TIMER_BITS) ")/(IMCLK/256)), "
31	"default=" __MODULE_STRING(TIMER_MARGIN) ")");
32
33static bool nowayout = WATCHDOG_NOWAYOUT;
34module_param(nowayout, bool, 0);
35MODULE_PARM_DESC(nowayout,
36	"Watchdog cannot be stopped once started "
37	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
38
39static struct txx9_tmr_reg __iomem *txx9wdt_reg;
40static struct clk *txx9_imclk;
41static DEFINE_SPINLOCK(txx9_lock);
42
43static int txx9wdt_ping(struct watchdog_device *wdt_dev)
44{
45	spin_lock(&txx9_lock);
46	__raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
47	spin_unlock(&txx9_lock);
48	return 0;
49}
50
51static int txx9wdt_start(struct watchdog_device *wdt_dev)
52{
53	spin_lock(&txx9_lock);
54	__raw_writel(WD_TIMER_CLK * wdt_dev->timeout, &txx9wdt_reg->cpra);
55	__raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr);
56	__raw_writel(0, &txx9wdt_reg->tisr);	/* clear pending interrupt */
57	__raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG,
58		     &txx9wdt_reg->tcr);
59	__raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
60	spin_unlock(&txx9_lock);
61	return 0;
62}
63
64static int txx9wdt_stop(struct watchdog_device *wdt_dev)
65{
66	spin_lock(&txx9_lock);
67	__raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr);
68	__raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE,
69		     &txx9wdt_reg->tcr);
70	spin_unlock(&txx9_lock);
71	return 0;
72}
73
74static int txx9wdt_set_timeout(struct watchdog_device *wdt_dev,
75			       unsigned int new_timeout)
76{
77	wdt_dev->timeout = new_timeout;
78	txx9wdt_stop(wdt_dev);
79	txx9wdt_start(wdt_dev);
80	return 0;
81}
82
83static const struct watchdog_info txx9wdt_info = {
84	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
85	.identity = "Hardware Watchdog for TXx9",
86};
87
88static const struct watchdog_ops txx9wdt_ops = {
89	.owner = THIS_MODULE,
90	.start = txx9wdt_start,
91	.stop = txx9wdt_stop,
92	.ping = txx9wdt_ping,
93	.set_timeout = txx9wdt_set_timeout,
94};
95
96static struct watchdog_device txx9wdt = {
97	.info = &txx9wdt_info,
98	.ops = &txx9wdt_ops,
99};
100
101static int txx9wdt_probe(struct platform_device *dev)
102{
103	int ret;
104
105	txx9_imclk = clk_get(NULL, "imbus_clk");
106	if (IS_ERR(txx9_imclk)) {
107		ret = PTR_ERR(txx9_imclk);
108		txx9_imclk = NULL;
109		goto exit;
110	}
111	ret = clk_prepare_enable(txx9_imclk);
112	if (ret) {
113		clk_put(txx9_imclk);
114		txx9_imclk = NULL;
115		goto exit;
116	}
117
118	txx9wdt_reg = devm_platform_ioremap_resource(dev, 0);
119	if (IS_ERR(txx9wdt_reg)) {
120		ret = PTR_ERR(txx9wdt_reg);
121		goto exit;
122	}
123
124	if (timeout < 1 || timeout > WD_MAX_TIMEOUT)
125		timeout = TIMER_MARGIN;
126	txx9wdt.timeout = timeout;
127	txx9wdt.min_timeout = 1;
128	txx9wdt.max_timeout = WD_MAX_TIMEOUT;
129	txx9wdt.parent = &dev->dev;
130	watchdog_set_nowayout(&txx9wdt, nowayout);
131
132	ret = watchdog_register_device(&txx9wdt);
133	if (ret)
134		goto exit;
135
136	pr_info("Hardware Watchdog Timer: timeout=%d sec (max %ld) (nowayout= %d)\n",
137		timeout, WD_MAX_TIMEOUT, nowayout);
138
139	return 0;
140exit:
141	if (txx9_imclk) {
142		clk_disable_unprepare(txx9_imclk);
143		clk_put(txx9_imclk);
144	}
145	return ret;
146}
147
148static void txx9wdt_remove(struct platform_device *dev)
149{
150	watchdog_unregister_device(&txx9wdt);
151	clk_disable_unprepare(txx9_imclk);
152	clk_put(txx9_imclk);
153}
154
155static void txx9wdt_shutdown(struct platform_device *dev)
156{
157	txx9wdt_stop(&txx9wdt);
158}
159
160static struct platform_driver txx9wdt_driver = {
161	.probe = txx9wdt_probe,
162	.remove_new = txx9wdt_remove,
163	.shutdown = txx9wdt_shutdown,
164	.driver = {
165		.name = "txx9wdt",
166	},
167};
168module_platform_driver(txx9wdt_driver);
169
170MODULE_DESCRIPTION("TXx9 Watchdog Driver");
171MODULE_LICENSE("GPL");
172MODULE_ALIAS("platform:txx9wdt");
173