1/*
2 * Moschip MCS814x Watchdog driver
3 *
4 * Copyright (C) 2012, Florian Fainelli <florian@openwrt.org>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
19 */
20
21#include <linux/module.h>
22#include <linux/slab.h>
23#include <linux/init.h>
24#include <linux/platform_device.h>
25#include <linux/miscdevice.h>
26#include <linux/watchdog.h>
27#include <linux/io.h>
28#include <linux/err.h>
29#include <linux/clk.h>
30#include <linux/of.h>
31
32#define WDT_COUNT	0x00
33#define WDT_CTRL	0x04
34#define  WDT_CTRL_EN	0x1
35
36/* watchdog frequency */
37#define WDT_MAX_VALUE	(0xffffffff)
38
39struct mcs814x_wdt {
40	void __iomem		*regs;
41	spinlock_t		lock;
42	struct watchdog_device	wdt_dev;
43	struct clk		*clk;
44};
45
46static int mcs814x_wdt_start(struct watchdog_device *dev)
47{
48	struct mcs814x_wdt *wdt = watchdog_get_drvdata(dev);
49	u32 reg;
50
51	spin_lock(&wdt->lock);
52	reg = readl_relaxed(wdt->regs + WDT_CTRL);
53	reg |= WDT_CTRL_EN;
54	writel_relaxed(reg, wdt->regs + WDT_CTRL);
55	spin_unlock(&wdt->lock);
56
57	return 0;
58}
59
60static int mcs814x_wdt_stop(struct watchdog_device *dev)
61{
62	struct mcs814x_wdt *wdt = watchdog_get_drvdata(dev);
63	u32 reg;
64
65	spin_lock(&wdt->lock);
66	reg = readl_relaxed(wdt->regs + WDT_CTRL);
67	reg &= ~WDT_CTRL_EN;
68	writel_relaxed(reg, wdt->regs + WDT_CTRL);
69	spin_unlock(&wdt->lock);
70
71	return 0;
72}
73
74static int mcs814x_wdt_set_timeout(struct watchdog_device *dev,
75				unsigned int new_timeout)
76{
77	struct mcs814x_wdt *wdt = watchdog_get_drvdata(dev);
78
79	spin_lock(&wdt->lock);
80	/* watchdog counts upward and rollover (0xfffffff -> 0)
81	 * triggers the reboot
82	 */
83	writel_relaxed(WDT_MAX_VALUE - (new_timeout * clk_get_rate(wdt->clk)),
84		wdt->regs + WDT_COUNT);
85	spin_unlock(&wdt->lock);
86
87	return 0;
88}
89
90static int mcs814x_wdt_ping(struct watchdog_device *dev)
91{
92	/* restart the watchdog */
93	mcs814x_wdt_stop(dev);
94	mcs814x_wdt_set_timeout(dev, dev->timeout);
95	mcs814x_wdt_start(dev);
96
97	return 0;
98}
99
100static const struct watchdog_info mcs814x_wdt_ident = {
101	.options	= WDIOF_CARDRESET | WDIOF_SETTIMEOUT |
102			  WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
103	.identity	= "MCS814x Watchdog",
104};
105
106static struct watchdog_ops mcs814x_wdt_ops = {
107	.owner		= THIS_MODULE,
108	.start		= mcs814x_wdt_start,
109	.stop		= mcs814x_wdt_stop,
110	.set_timeout	= mcs814x_wdt_set_timeout,
111	.ping		= mcs814x_wdt_ping,
112};
113
114static int mcs814x_wdt_probe(struct platform_device *pdev)
115{
116	struct resource *res;
117	struct mcs814x_wdt *wdt;
118	int ret;
119	struct clk *clk;
120
121	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
122	if (!res)
123		return -ENODEV;
124
125	clk = clk_get(NULL, "wdt");
126	if (IS_ERR_OR_NULL(clk)) {
127		dev_err(&pdev->dev, "failed to get watchdog clock\n");
128		return PTR_ERR(clk);
129	}
130
131	wdt = kzalloc(sizeof(*wdt), GFP_KERNEL);
132	if (!wdt) {
133		ret = -ENOMEM;
134		goto out_clk;
135	}
136
137	spin_lock_init(&wdt->lock);
138	wdt->clk = clk;
139	wdt->wdt_dev.info = &mcs814x_wdt_ident;
140	wdt->wdt_dev.ops = &mcs814x_wdt_ops;
141	wdt->wdt_dev.min_timeout = 1;
142	/* approximately 10995 secs */
143	wdt->wdt_dev.max_timeout = (WDT_MAX_VALUE / clk_get_rate(clk));
144
145	platform_set_drvdata(pdev, wdt);
146
147	/* only ioremap registers, because the register is shared */
148	wdt->regs = devm_ioremap(&pdev->dev, res->start, resource_size(res));
149	if (!wdt->regs) {
150		ret = -ENOMEM;
151		goto out;
152	}
153
154	watchdog_set_drvdata(&wdt->wdt_dev, wdt);
155
156	ret = watchdog_register_device(&wdt->wdt_dev);
157	if (ret) {
158		dev_err(&pdev->dev, "cannot register watchdog: %d\n", ret);
159		goto out;
160	}
161
162	dev_info(&pdev->dev, "registered\n");
163	return 0;
164
165out:
166	platform_set_drvdata(pdev, NULL);
167	kfree(wdt);
168out_clk:
169	clk_put(clk);
170	return ret;
171}
172
173static int mcs814x_wdt_remove(struct platform_device *pdev)
174{
175	struct mcs814x_wdt *wdt = platform_get_drvdata(pdev);
176
177	clk_put(wdt->clk);
178	watchdog_unregister_device(&wdt->wdt_dev);
179	watchdog_set_drvdata(&wdt->wdt_dev, NULL);
180	kfree(wdt);
181	platform_set_drvdata(pdev, NULL);
182
183	return 0;
184}
185
186static const struct of_device_id mcs814x_wdt_ids[] = {
187	{ .compatible = "moschip,mcs814x-wdt", },
188	{ /* sentinel */ },
189};
190
191static struct platform_driver mcs814x_wdt_driver = {
192	.driver	= {
193		.name	= "mcs814x-wdt",
194		.owner	= THIS_MODULE,
195		.of_match_table = mcs814x_wdt_ids,
196	},
197	.probe		= mcs814x_wdt_probe,
198	.remove		= mcs814x_wdt_remove,
199};
200
201module_platform_driver(mcs814x_wdt_driver);
202
203MODULE_AUTHOR("Florian Fainelli <florian@openwrt.org>");
204MODULE_DESCRIPTION("Moschip MCS814x Watchdog driver");
205MODULE_LICENSE("GPL");
206MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
207MODULE_ALIAS("platform:mcs814x-wdt");
208