1// SPDX-License-Identifier: GPL-2.0
2/*
3 * MStar WDT driver
4 *
5 * Copyright (C) 2019 - 2021 Daniel Palmer
6 * Copyright (C) 2021 Romain Perier
7 *
8 */
9
10#include <linux/clk.h>
11#include <linux/io.h>
12#include <linux/mod_devicetable.h>
13#include <linux/module.h>
14#include <linux/platform_device.h>
15#include <linux/watchdog.h>
16
17#define REG_WDT_CLR			0x0
18#define REG_WDT_MAX_PRD_L		0x10
19#define REG_WDT_MAX_PRD_H		0x14
20
21#define MSC313E_WDT_MIN_TIMEOUT		1
22#define MSC313E_WDT_DEFAULT_TIMEOUT	30
23
24static unsigned int timeout;
25
26module_param(timeout, int, 0);
27MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds");
28
29struct msc313e_wdt_priv {
30	void __iomem *base;
31	struct watchdog_device wdev;
32	struct clk *clk;
33};
34
35static int msc313e_wdt_start(struct watchdog_device *wdev)
36{
37	struct msc313e_wdt_priv *priv = watchdog_get_drvdata(wdev);
38	u32 timeout;
39	int err;
40
41	err = clk_prepare_enable(priv->clk);
42	if (err)
43		return err;
44
45	timeout = wdev->timeout * clk_get_rate(priv->clk);
46	writew(timeout & 0xffff, priv->base + REG_WDT_MAX_PRD_L);
47	writew((timeout >> 16) & 0xffff, priv->base + REG_WDT_MAX_PRD_H);
48	writew(1, priv->base + REG_WDT_CLR);
49	return 0;
50}
51
52static int msc313e_wdt_ping(struct watchdog_device *wdev)
53{
54	struct msc313e_wdt_priv *priv = watchdog_get_drvdata(wdev);
55
56	writew(1, priv->base + REG_WDT_CLR);
57	return 0;
58}
59
60static int msc313e_wdt_stop(struct watchdog_device *wdev)
61{
62	struct msc313e_wdt_priv *priv = watchdog_get_drvdata(wdev);
63
64	writew(0, priv->base + REG_WDT_MAX_PRD_L);
65	writew(0, priv->base + REG_WDT_MAX_PRD_H);
66	writew(0, priv->base + REG_WDT_CLR);
67	clk_disable_unprepare(priv->clk);
68	return 0;
69}
70
71static int msc313e_wdt_settimeout(struct watchdog_device *wdev, unsigned int new_time)
72{
73	wdev->timeout = new_time;
74
75	return msc313e_wdt_start(wdev);
76}
77
78static const struct watchdog_info msc313e_wdt_ident = {
79	.identity = "MSC313e watchdog",
80	.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
81};
82
83static const struct watchdog_ops msc313e_wdt_ops = {
84	.owner = THIS_MODULE,
85	.start = msc313e_wdt_start,
86	.stop = msc313e_wdt_stop,
87	.ping = msc313e_wdt_ping,
88	.set_timeout = msc313e_wdt_settimeout,
89};
90
91static const struct of_device_id msc313e_wdt_of_match[] = {
92	{ .compatible = "mstar,msc313e-wdt", },
93	{ /* sentinel */ }
94};
95MODULE_DEVICE_TABLE(of, msc313e_wdt_of_match);
96
97static int msc313e_wdt_probe(struct platform_device *pdev)
98{
99	struct device *dev = &pdev->dev;
100	struct msc313e_wdt_priv *priv;
101
102	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
103	if (!priv)
104		return -ENOMEM;
105
106	priv->base = devm_platform_ioremap_resource(pdev, 0);
107	if (IS_ERR(priv->base))
108		return PTR_ERR(priv->base);
109
110	priv->clk = devm_clk_get(dev, NULL);
111	if (IS_ERR(priv->clk)) {
112		dev_err(dev, "No input clock\n");
113		return PTR_ERR(priv->clk);
114	}
115
116	priv->wdev.info = &msc313e_wdt_ident,
117	priv->wdev.ops = &msc313e_wdt_ops,
118	priv->wdev.parent = dev;
119	priv->wdev.min_timeout = MSC313E_WDT_MIN_TIMEOUT;
120	priv->wdev.max_timeout = U32_MAX / clk_get_rate(priv->clk);
121	priv->wdev.timeout = MSC313E_WDT_DEFAULT_TIMEOUT;
122
123	/* If the period is non-zero the WDT is running */
124	if (readw(priv->base + REG_WDT_MAX_PRD_L) | (readw(priv->base + REG_WDT_MAX_PRD_H) << 16))
125		set_bit(WDOG_HW_RUNNING, &priv->wdev.status);
126
127	watchdog_set_drvdata(&priv->wdev, priv);
128
129	watchdog_init_timeout(&priv->wdev, timeout, dev);
130	watchdog_stop_on_reboot(&priv->wdev);
131	watchdog_stop_on_unregister(&priv->wdev);
132
133	return devm_watchdog_register_device(dev, &priv->wdev);
134}
135
136static int __maybe_unused msc313e_wdt_suspend(struct device *dev)
137{
138	struct msc313e_wdt_priv *priv = dev_get_drvdata(dev);
139
140	if (watchdog_active(&priv->wdev))
141		msc313e_wdt_stop(&priv->wdev);
142
143	return 0;
144}
145
146static int __maybe_unused msc313e_wdt_resume(struct device *dev)
147{
148	struct msc313e_wdt_priv *priv = dev_get_drvdata(dev);
149
150	if (watchdog_active(&priv->wdev))
151		msc313e_wdt_start(&priv->wdev);
152
153	return 0;
154}
155
156static SIMPLE_DEV_PM_OPS(msc313e_wdt_pm_ops, msc313e_wdt_suspend, msc313e_wdt_resume);
157
158static struct platform_driver msc313e_wdt_driver = {
159	.driver = {
160		.name = "msc313e-wdt",
161		.of_match_table = msc313e_wdt_of_match,
162		.pm = &msc313e_wdt_pm_ops,
163	},
164	.probe = msc313e_wdt_probe,
165};
166module_platform_driver(msc313e_wdt_driver);
167
168MODULE_AUTHOR("Daniel Palmer <daniel@thingy.jp>");
169MODULE_DESCRIPTION("Watchdog driver for MStar MSC313e");
170MODULE_LICENSE("GPL v2");
171