1// SPDX-License-Identifier: GPL-2.0+
2/*
3 *  Copyright (C) 2015 Mans Rullgard <mans@mansr.com>
4 *  SMP86xx/SMP87xx Watchdog driver
5 */
6
7#include <linux/bitops.h>
8#include <linux/clk.h>
9#include <linux/delay.h>
10#include <linux/io.h>
11#include <linux/kernel.h>
12#include <linux/module.h>
13#include <linux/moduleparam.h>
14#include <linux/mod_devicetable.h>
15#include <linux/platform_device.h>
16#include <linux/watchdog.h>
17
18#define DEFAULT_TIMEOUT 30
19
20static bool nowayout = WATCHDOG_NOWAYOUT;
21module_param(nowayout, bool, 0);
22MODULE_PARM_DESC(nowayout,
23		 "Watchdog cannot be stopped once started (default="
24		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
25
26static unsigned int timeout;
27module_param(timeout, int, 0);
28MODULE_PARM_DESC(timeout, "Watchdog timeout");
29
30/*
31 * Counter counts down from programmed value.  Reset asserts when
32 * the counter reaches 1.
33 */
34#define WD_COUNTER		0
35
36#define WD_CONFIG		4
37#define WD_CONFIG_XTAL_IN	BIT(0)
38#define WD_CONFIG_DISABLE	BIT(31)
39
40struct tangox_wdt_device {
41	struct watchdog_device wdt;
42	void __iomem *base;
43	unsigned long clk_rate;
44	struct clk *clk;
45};
46
47static int tangox_wdt_set_timeout(struct watchdog_device *wdt,
48				  unsigned int new_timeout)
49{
50	wdt->timeout = new_timeout;
51
52	return 0;
53}
54
55static int tangox_wdt_start(struct watchdog_device *wdt)
56{
57	struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
58	u32 ticks;
59
60	ticks = 1 + wdt->timeout * dev->clk_rate;
61	writel(ticks, dev->base + WD_COUNTER);
62
63	return 0;
64}
65
66static int tangox_wdt_stop(struct watchdog_device *wdt)
67{
68	struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
69
70	writel(0, dev->base + WD_COUNTER);
71
72	return 0;
73}
74
75static unsigned int tangox_wdt_get_timeleft(struct watchdog_device *wdt)
76{
77	struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
78	u32 count;
79
80	count = readl(dev->base + WD_COUNTER);
81
82	if (!count)
83		return 0;
84
85	return (count - 1) / dev->clk_rate;
86}
87
88static const struct watchdog_info tangox_wdt_info = {
89	.options  = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
90	.identity = "tangox watchdog",
91};
92
93static int tangox_wdt_restart(struct watchdog_device *wdt,
94			      unsigned long action, void *data)
95{
96	struct tangox_wdt_device *dev = watchdog_get_drvdata(wdt);
97
98	writel(1, dev->base + WD_COUNTER);
99
100	return 0;
101}
102
103static const struct watchdog_ops tangox_wdt_ops = {
104	.start		= tangox_wdt_start,
105	.stop		= tangox_wdt_stop,
106	.set_timeout	= tangox_wdt_set_timeout,
107	.get_timeleft	= tangox_wdt_get_timeleft,
108	.restart	= tangox_wdt_restart,
109};
110
111static void tangox_clk_disable_unprepare(void *data)
112{
113	clk_disable_unprepare(data);
114}
115
116static int tangox_wdt_probe(struct platform_device *pdev)
117{
118	struct tangox_wdt_device *dev;
119	u32 config;
120	int err;
121
122	dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
123	if (!dev)
124		return -ENOMEM;
125
126	dev->base = devm_platform_ioremap_resource(pdev, 0);
127	if (IS_ERR(dev->base))
128		return PTR_ERR(dev->base);
129
130	dev->clk = devm_clk_get(&pdev->dev, NULL);
131	if (IS_ERR(dev->clk))
132		return PTR_ERR(dev->clk);
133
134	err = clk_prepare_enable(dev->clk);
135	if (err)
136		return err;
137	err = devm_add_action_or_reset(&pdev->dev,
138				       tangox_clk_disable_unprepare, dev->clk);
139	if (err)
140		return err;
141
142	dev->clk_rate = clk_get_rate(dev->clk);
143	if (!dev->clk_rate)
144		return -EINVAL;
145
146	dev->wdt.parent = &pdev->dev;
147	dev->wdt.info = &tangox_wdt_info;
148	dev->wdt.ops = &tangox_wdt_ops;
149	dev->wdt.timeout = DEFAULT_TIMEOUT;
150	dev->wdt.min_timeout = 1;
151	dev->wdt.max_hw_heartbeat_ms = (U32_MAX - 1) / dev->clk_rate;
152
153	watchdog_init_timeout(&dev->wdt, timeout, &pdev->dev);
154	watchdog_set_nowayout(&dev->wdt, nowayout);
155	watchdog_set_drvdata(&dev->wdt, dev);
156
157	/*
158	 * Deactivate counter if disable bit is set to avoid
159	 * accidental reset.
160	 */
161	config = readl(dev->base + WD_CONFIG);
162	if (config & WD_CONFIG_DISABLE)
163		writel(0, dev->base + WD_COUNTER);
164
165	writel(WD_CONFIG_XTAL_IN, dev->base + WD_CONFIG);
166
167	/*
168	 * Mark as active and restart with configured timeout if
169	 * already running.
170	 */
171	if (readl(dev->base + WD_COUNTER)) {
172		set_bit(WDOG_HW_RUNNING, &dev->wdt.status);
173		tangox_wdt_start(&dev->wdt);
174	}
175
176	watchdog_set_restart_priority(&dev->wdt, 128);
177
178	watchdog_stop_on_unregister(&dev->wdt);
179	err = devm_watchdog_register_device(&pdev->dev, &dev->wdt);
180	if (err)
181		return err;
182
183	platform_set_drvdata(pdev, dev);
184
185	dev_info(&pdev->dev, "SMP86xx/SMP87xx watchdog registered\n");
186
187	return 0;
188}
189
190static const struct of_device_id tangox_wdt_dt_ids[] = {
191	{ .compatible = "sigma,smp8642-wdt" },
192	{ .compatible = "sigma,smp8759-wdt" },
193	{ }
194};
195MODULE_DEVICE_TABLE(of, tangox_wdt_dt_ids);
196
197static struct platform_driver tangox_wdt_driver = {
198	.probe	= tangox_wdt_probe,
199	.driver	= {
200		.name		= "tangox-wdt",
201		.of_match_table	= tangox_wdt_dt_ids,
202	},
203};
204
205module_platform_driver(tangox_wdt_driver);
206
207MODULE_AUTHOR("Mans Rullgard <mans@mansr.com>");
208MODULE_DESCRIPTION("SMP86xx/SMP87xx Watchdog driver");
209MODULE_LICENSE("GPL");
210