1/*
  2 * MOXA ART SoCs watchdog driver.
  3 *
  4 * Copyright (C) 2013 Jonas Jensen
  5 *
  6 * Jonas Jensen <jonas.jensen@gmail.com>
  7 *
  8 * This file is licensed under the terms of the GNU General Public
  9 * License version 2.  This program is licensed "as is" without any
 10 * warranty of any kind, whether express or implied.
 11 */
 12
 13#include <linux/clk.h>
 14#include <linux/io.h>
 15#include <linux/module.h>
 16#include <linux/mod_devicetable.h>
 17#include <linux/err.h>
 18#include <linux/kernel.h>
 19#include <linux/platform_device.h>
 20#include <linux/watchdog.h>
 21#include <linux/moduleparam.h>
 22
 23#define REG_COUNT			0x4
 24#define REG_MODE			0x8
 25#define REG_ENABLE			0xC
 26
 27struct moxart_wdt_dev {
 28	struct watchdog_device dev;
 29	void __iomem *base;
 30	unsigned int clock_frequency;
 31};
 32
 33static int heartbeat;
 34
 35static int moxart_wdt_restart(struct watchdog_device *wdt_dev,
 36			      unsigned long action, void *data)
 37{
 38	struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 39
 40	writel(1, moxart_wdt->base + REG_COUNT);
 41	writel(0x5ab9, moxart_wdt->base + REG_MODE);
 42	writel(0x03, moxart_wdt->base + REG_ENABLE);
 43
 44	return 0;
 45}
 46
 47static int moxart_wdt_stop(struct watchdog_device *wdt_dev)
 48{
 49	struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 50
 51	writel(0, moxart_wdt->base + REG_ENABLE);
 52
 53	return 0;
 54}
 55
 56static int moxart_wdt_start(struct watchdog_device *wdt_dev)
 57{
 58	struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 59
 60	writel(moxart_wdt->clock_frequency * wdt_dev->timeout,
 61	       moxart_wdt->base + REG_COUNT);
 62	writel(0x5ab9, moxart_wdt->base + REG_MODE);
 63	writel(0x03, moxart_wdt->base + REG_ENABLE);
 64
 65	return 0;
 66}
 67
 68static int moxart_wdt_set_timeout(struct watchdog_device *wdt_dev,
 69				  unsigned int timeout)
 70{
 71	wdt_dev->timeout = timeout;
 72
 73	return 0;
 74}
 75
 76static const struct watchdog_info moxart_wdt_info = {
 77	.identity       = "moxart-wdt",
 78	.options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 79			  WDIOF_MAGICCLOSE,
 80};
 81
 82static const struct watchdog_ops moxart_wdt_ops = {
 83	.owner          = THIS_MODULE,
 84	.start          = moxart_wdt_start,
 85	.stop           = moxart_wdt_stop,
 86	.set_timeout    = moxart_wdt_set_timeout,
 87	.restart        = moxart_wdt_restart,
 88};
 89
 90static int moxart_wdt_probe(struct platform_device *pdev)
 91{
 92	struct moxart_wdt_dev *moxart_wdt;
 93	struct device *dev = &pdev->dev;
 94	struct clk *clk;
 95	int err;
 96	unsigned int max_timeout;
 97	bool nowayout = WATCHDOG_NOWAYOUT;
 98
 99	moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
100	if (!moxart_wdt)
101		return -ENOMEM;
102
103	platform_set_drvdata(pdev, moxart_wdt);
104
105	moxart_wdt->base = devm_platform_ioremap_resource(pdev, 0);
106	if (IS_ERR(moxart_wdt->base))
107		return PTR_ERR(moxart_wdt->base);
108
109	clk = devm_clk_get(dev, NULL);
110	if (IS_ERR(clk)) {
111		pr_err("%s: of_clk_get failed\n", __func__);
112		return PTR_ERR(clk);
113	}
114
115	moxart_wdt->clock_frequency = clk_get_rate(clk);
116	if (moxart_wdt->clock_frequency == 0) {
117		pr_err("%s: incorrect clock frequency\n", __func__);
118		return -EINVAL;
119	}
120
121	max_timeout = UINT_MAX / moxart_wdt->clock_frequency;
122
123	moxart_wdt->dev.info = &moxart_wdt_info;
124	moxart_wdt->dev.ops = &moxart_wdt_ops;
125	moxart_wdt->dev.timeout = max_timeout;
126	moxart_wdt->dev.min_timeout = 1;
127	moxart_wdt->dev.max_timeout = max_timeout;
128	moxart_wdt->dev.parent = dev;
129
130	watchdog_init_timeout(&moxart_wdt->dev, heartbeat, dev);
131	watchdog_set_nowayout(&moxart_wdt->dev, nowayout);
132	watchdog_set_restart_priority(&moxart_wdt->dev, 128);
133
134	watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
135
136	watchdog_stop_on_unregister(&moxart_wdt->dev);
137	err = devm_watchdog_register_device(dev, &moxart_wdt->dev);
138	if (err)
139		return err;
140
141	dev_dbg(dev, "Watchdog enabled (heartbeat=%d sec, nowayout=%d)\n",
142		moxart_wdt->dev.timeout, nowayout);
143
144	return 0;
145}
146
147static const struct of_device_id moxart_watchdog_match[] = {
148	{ .compatible = "moxa,moxart-watchdog" },
149	{ },
150};
151MODULE_DEVICE_TABLE(of, moxart_watchdog_match);
152
153static struct platform_driver moxart_wdt_driver = {
154	.probe      = moxart_wdt_probe,
155	.driver     = {
156		.name		= "moxart-watchdog",
157		.of_match_table	= moxart_watchdog_match,
158	},
159};
160module_platform_driver(moxart_wdt_driver);
161
162module_param(heartbeat, int, 0);
163MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
164
165MODULE_DESCRIPTION("MOXART watchdog driver");
166MODULE_LICENSE("GPL");
167MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");