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/err.h>
 17#include <linux/kernel.h>
 18#include <linux/platform_device.h>
 19#include <linux/watchdog.h>
 20#include <linux/moduleparam.h>
 21
 22#define REG_COUNT			0x4
 23#define REG_MODE			0x8
 24#define REG_ENABLE			0xC
 25
 26struct moxart_wdt_dev {
 27	struct watchdog_device dev;
 28	void __iomem *base;
 29	unsigned int clock_frequency;
 30};
 31
 32static int heartbeat;
 33
 34static int moxart_wdt_restart(struct watchdog_device *wdt_dev,
 35			      unsigned long action, void *data)
 36{
 37	struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 38
 39	writel(1, moxart_wdt->base + REG_COUNT);
 40	writel(0x5ab9, moxart_wdt->base + REG_MODE);
 41	writel(0x03, moxart_wdt->base + REG_ENABLE);
 42
 43	return 0;
 44}
 45
 46static int moxart_wdt_stop(struct watchdog_device *wdt_dev)
 47{
 48	struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 49
 50	writel(0, moxart_wdt->base + REG_ENABLE);
 51
 52	return 0;
 53}
 54
 55static int moxart_wdt_start(struct watchdog_device *wdt_dev)
 56{
 57	struct moxart_wdt_dev *moxart_wdt = watchdog_get_drvdata(wdt_dev);
 58
 59	writel(moxart_wdt->clock_frequency * wdt_dev->timeout,
 60	       moxart_wdt->base + REG_COUNT);
 61	writel(0x5ab9, moxart_wdt->base + REG_MODE);
 62	writel(0x03, moxart_wdt->base + REG_ENABLE);
 63
 64	return 0;
 65}
 66
 67static int moxart_wdt_set_timeout(struct watchdog_device *wdt_dev,
 68				  unsigned int timeout)
 69{
 70	wdt_dev->timeout = timeout;
 71
 72	return 0;
 73}
 74
 75static const struct watchdog_info moxart_wdt_info = {
 76	.identity       = "moxart-wdt",
 77	.options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 78			  WDIOF_MAGICCLOSE,
 79};
 80
 81static const struct watchdog_ops moxart_wdt_ops = {
 82	.owner          = THIS_MODULE,
 83	.start          = moxart_wdt_start,
 84	.stop           = moxart_wdt_stop,
 85	.set_timeout    = moxart_wdt_set_timeout,
 86	.restart        = moxart_wdt_restart,
 87};
 88
 89static int moxart_wdt_probe(struct platform_device *pdev)
 90{
 91	struct moxart_wdt_dev *moxart_wdt;
 92	struct device *dev = &pdev->dev;
 93	struct device_node *node = dev->of_node;
 94	struct resource *res;
 95	struct clk *clk;
 96	int err;
 97	unsigned int max_timeout;
 98	bool nowayout = WATCHDOG_NOWAYOUT;
 99
100	moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
101	if (!moxart_wdt)
102		return -ENOMEM;
103
104	platform_set_drvdata(pdev, moxart_wdt);
105
106	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
107	moxart_wdt->base = devm_ioremap_resource(dev, res);
108	if (IS_ERR(moxart_wdt->base))
109		return PTR_ERR(moxart_wdt->base);
110
111	clk = of_clk_get(node, 0);
112	if (IS_ERR(clk)) {
113		pr_err("%s: of_clk_get failed\n", __func__);
114		return PTR_ERR(clk);
115	}
116
117	moxart_wdt->clock_frequency = clk_get_rate(clk);
118	if (moxart_wdt->clock_frequency == 0) {
119		pr_err("%s: incorrect clock frequency\n", __func__);
120		return -EINVAL;
121	}
122
123	max_timeout = UINT_MAX / moxart_wdt->clock_frequency;
124
125	moxart_wdt->dev.info = &moxart_wdt_info;
126	moxart_wdt->dev.ops = &moxart_wdt_ops;
127	moxart_wdt->dev.timeout = max_timeout;
128	moxart_wdt->dev.min_timeout = 1;
129	moxart_wdt->dev.max_timeout = max_timeout;
130	moxart_wdt->dev.parent = dev;
131
132	watchdog_init_timeout(&moxart_wdt->dev, heartbeat, dev);
133	watchdog_set_nowayout(&moxart_wdt->dev, nowayout);
134	watchdog_set_restart_priority(&moxart_wdt->dev, 128);
135
136	watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
137
138	err = watchdog_register_device(&moxart_wdt->dev);
139	if (err)
140		return err;
141
142	dev_dbg(dev, "Watchdog enabled (heartbeat=%d sec, nowayout=%d)\n",
143		moxart_wdt->dev.timeout, nowayout);
144
145	return 0;
146}
147
148static int moxart_wdt_remove(struct platform_device *pdev)
149{
150	struct moxart_wdt_dev *moxart_wdt = platform_get_drvdata(pdev);
151
152	moxart_wdt_stop(&moxart_wdt->dev);
153
154	return 0;
155}
156
157static const struct of_device_id moxart_watchdog_match[] = {
158	{ .compatible = "moxa,moxart-watchdog" },
159	{ },
160};
161MODULE_DEVICE_TABLE(of, moxart_watchdog_match);
162
163static struct platform_driver moxart_wdt_driver = {
164	.probe      = moxart_wdt_probe,
165	.remove     = moxart_wdt_remove,
166	.driver     = {
167		.name		= "moxart-watchdog",
168		.of_match_table	= moxart_watchdog_match,
169	},
170};
171module_platform_driver(moxart_wdt_driver);
172
173module_param(heartbeat, int, 0);
174MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
175
176MODULE_DESCRIPTION("MOXART watchdog driver");
177MODULE_LICENSE("GPL");
178MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");