1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * MOXA ART SoCs watchdog driver.
  4 *
  5 * Copyright (C) 2013 Jonas Jensen
  6 *
  7 * Jonas Jensen <jonas.jensen@gmail.com>
  8 *
  9 */
 10
 11#include <linux/clk.h>
 12#include <linux/io.h>
 13#include <linux/module.h>
 14#include <linux/mod_devicetable.h>
 15#include <linux/err.h>
 16#include <linux/kernel.h>
 17#include <linux/platform_device.h>
 18#include <linux/watchdog.h>
 19#include <linux/moduleparam.h>
 20
 21#define REG_COUNT			0x4
 22#define REG_MODE			0x8
 23#define REG_ENABLE			0xC
 24
 25struct moxart_wdt_dev {
 26	struct watchdog_device dev;
 27	void __iomem *base;
 28	unsigned int clock_frequency;
 29};
 30
 31static int heartbeat;
 32
 33static int moxart_wdt_restart(struct watchdog_device *wdt_dev,
 34			      unsigned long action, void *data)
 35{
 36	struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 37
 38	writel(1, moxart_wdt->base + REG_COUNT);
 39	writel(0x5ab9, moxart_wdt->base + REG_MODE);
 40	writel(0x03, moxart_wdt->base + REG_ENABLE);
 41
 42	return 0;
 43}
 44
 45static int moxart_wdt_stop(struct watchdog_device *wdt_dev)
 46{
 47	struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 48
 49	writel(0, moxart_wdt->base + REG_ENABLE);
 50
 51	return 0;
 52}
 53
 54static int moxart_wdt_start(struct watchdog_device *wdt_dev)
 55{
 56	struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 57
 58	writel(moxart_wdt->clock_frequency * wdt_dev->timeout,
 59	       moxart_wdt->base + REG_COUNT);
 60	writel(0x5ab9, moxart_wdt->base + REG_MODE);
 61	writel(0x03, moxart_wdt->base + REG_ENABLE);
 62
 63	return 0;
 64}
 65
 66static int moxart_wdt_set_timeout(struct watchdog_device *wdt_dev,
 67				  unsigned int timeout)
 68{
 69	wdt_dev->timeout = timeout;
 70
 71	return 0;
 72}
 73
 74static const struct watchdog_info moxart_wdt_info = {
 75	.identity       = "moxart-wdt",
 76	.options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 77			  WDIOF_MAGICCLOSE,
 78};
 79
 80static const struct watchdog_ops moxart_wdt_ops = {
 81	.owner          = THIS_MODULE,
 82	.start          = moxart_wdt_start,
 83	.stop           = moxart_wdt_stop,
 84	.set_timeout    = moxart_wdt_set_timeout,
 85	.restart        = moxart_wdt_restart,
 86};
 87
 88static int moxart_wdt_probe(struct platform_device *pdev)
 89{
 90	struct moxart_wdt_dev *moxart_wdt;
 91	struct device *dev = &pdev->dev;
 92	struct clk *clk;
 93	int err;
 94	unsigned int max_timeout;
 95	bool nowayout = WATCHDOG_NOWAYOUT;
 96
 97	moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
 98	if (!moxart_wdt)
 99		return -ENOMEM;
100
101	platform_set_drvdata(pdev, moxart_wdt);
102
103	moxart_wdt->base = devm_platform_ioremap_resource(pdev, 0);
104	if (IS_ERR(moxart_wdt->base))
105		return PTR_ERR(moxart_wdt->base);
106
107	clk = devm_clk_get(dev, NULL);
108	if (IS_ERR(clk)) {
109		pr_err("%s: of_clk_get failed\n", __func__);
110		return PTR_ERR(clk);
111	}
112
113	moxart_wdt->clock_frequency = clk_get_rate(clk);
114	if (moxart_wdt->clock_frequency == 0) {
115		pr_err("%s: incorrect clock frequency\n", __func__);
116		return -EINVAL;
117	}
118
119	max_timeout = UINT_MAX / moxart_wdt->clock_frequency;
120
121	moxart_wdt->dev.info = &moxart_wdt_info;
122	moxart_wdt->dev.ops = &moxart_wdt_ops;
123	moxart_wdt->dev.timeout = max_timeout;
124	moxart_wdt->dev.min_timeout = 1;
125	moxart_wdt->dev.max_timeout = max_timeout;
126	moxart_wdt->dev.parent = dev;
127
128	watchdog_init_timeout(&moxart_wdt->dev, heartbeat, dev);
129	watchdog_set_nowayout(&moxart_wdt->dev, nowayout);
130	watchdog_set_restart_priority(&moxart_wdt->dev, 128);
131
132	watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
133
134	watchdog_stop_on_unregister(&moxart_wdt->dev);
135	err = devm_watchdog_register_device(dev, &moxart_wdt->dev);
136	if (err)
137		return err;
138
139	dev_dbg(dev, "Watchdog enabled (heartbeat=%d sec, nowayout=%d)\n",
140		moxart_wdt->dev.timeout, nowayout);
141
142	return 0;
143}
144
145static const struct of_device_id moxart_watchdog_match[] = {
146	{ .compatible = "moxa,moxart-watchdog" },
147	{ },
148};
149MODULE_DEVICE_TABLE(of, moxart_watchdog_match);
150
151static struct platform_driver moxart_wdt_driver = {
152	.probe      = moxart_wdt_probe,
153	.driver     = {
154		.name		= "moxart-watchdog",
155		.of_match_table	= moxart_watchdog_match,
156	},
157};
158module_platform_driver(moxart_wdt_driver);
159
160module_param(heartbeat, int, 0);
161MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
162
163MODULE_DESCRIPTION("MOXART watchdog driver");
164MODULE_LICENSE("GPL");
165MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");