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#include <asm/system_misc.h>
 23
 24#define REG_COUNT			0x4
 25#define REG_MODE			0x8
 26#define REG_ENABLE			0xC
 27
 28struct moxart_wdt_dev {
 29	struct watchdog_device dev;
 30	void __iomem *base;
 31	unsigned int clock_frequency;
 32};
 33
 34static struct moxart_wdt_dev *moxart_restart_ctx;
 35
 36static int heartbeat;
 37
 38static void moxart_wdt_restart(enum reboot_mode reboot_mode, const char *cmd)
 39{
 40	writel(1, moxart_restart_ctx->base + REG_COUNT);
 41	writel(0x5ab9, moxart_restart_ctx->base + REG_MODE);
 42	writel(0x03, moxart_restart_ctx->base + REG_ENABLE);
 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};
 86
 87static int moxart_wdt_probe(struct platform_device *pdev)
 88{
 89	struct moxart_wdt_dev *moxart_wdt;
 90	struct device *dev = &pdev->dev;
 91	struct device_node *node = dev->of_node;
 92	struct resource *res;
 93	struct clk *clk;
 94	int err;
 95	unsigned int max_timeout;
 96	bool nowayout = WATCHDOG_NOWAYOUT;
 97
 98	moxart_wdt = devm_kzalloc(dev, sizeof(*moxart_wdt), GFP_KERNEL);
 99	if (!moxart_wdt)
100		return -ENOMEM;
101
102	platform_set_drvdata(pdev, moxart_wdt);
103
104	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
105	moxart_wdt->base = devm_ioremap_resource(dev, res);
106	if (IS_ERR(moxart_wdt->base))
107		return PTR_ERR(moxart_wdt->base);
108
109	clk = of_clk_get(node, 0);
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
133	watchdog_set_drvdata(&moxart_wdt->dev, moxart_wdt);
134
135	err = watchdog_register_device(&moxart_wdt->dev);
136	if (err)
137		return err;
138
139	moxart_restart_ctx = moxart_wdt;
140	arm_pm_restart = moxart_wdt_restart;
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	arm_pm_restart = NULL;
153	moxart_wdt_stop(&moxart_wdt->dev);
154	watchdog_unregister_device(&moxart_wdt->dev);
155
156	return 0;
157}
158
159static const struct of_device_id moxart_watchdog_match[] = {
160	{ .compatible = "moxa,moxart-watchdog" },
161	{ },
162};
163
164static struct platform_driver moxart_wdt_driver = {
165	.probe      = moxart_wdt_probe,
166	.remove     = moxart_wdt_remove,
167	.driver     = {
168		.name		= "moxart-watchdog",
169		.owner		= THIS_MODULE,
170		.of_match_table	= moxart_watchdog_match,
171	},
172};
173module_platform_driver(moxart_wdt_driver);
174
175module_param(heartbeat, int, 0);
176MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds");
177
178MODULE_DESCRIPTION("MOXART watchdog driver");
179MODULE_LICENSE("GPL");
180MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");