1/*
  2 *      Meson Watchdog Driver
  3 *
  4 *      Copyright (c) 2014 Carlo Caione
  5 *
  6 *      This program is free software; you can redistribute it and/or
  7 *      modify it under the terms of the GNU General Public License
  8 *      as published by the Free Software Foundation; either version
  9 *      2 of the License, or (at your option) any later version.
 10 */
 11
 12#include <linux/clk.h>
 13#include <linux/delay.h>
 14#include <linux/err.h>
 15#include <linux/init.h>
 16#include <linux/io.h>
 17#include <linux/kernel.h>
 18#include <linux/module.h>
 19#include <linux/moduleparam.h>
 20#include <linux/of.h>
 21#include <linux/of_device.h>
 22#include <linux/platform_device.h>
 23#include <linux/types.h>
 24#include <linux/watchdog.h>
 25
 26#define DRV_NAME		"meson_wdt"
 27
 28#define MESON_WDT_TC		0x00
 29#define MESON_WDT_DC_RESET	(3 << 24)
 30
 31#define MESON_WDT_RESET		0x04
 32
 33#define MESON_WDT_TIMEOUT	30
 34#define MESON_WDT_MIN_TIMEOUT	1
 35
 36#define MESON_SEC_TO_TC(s, c)	((s) * (c))
 37
 38static bool nowayout = WATCHDOG_NOWAYOUT;
 39static unsigned int timeout = MESON_WDT_TIMEOUT;
 40
 41struct meson_wdt_data {
 42	unsigned int enable;
 43	unsigned int terminal_count_mask;
 44	unsigned int count_unit;
 45};
 46
 47static struct meson_wdt_data meson6_wdt_data = {
 48	.enable			= BIT(22),
 49	.terminal_count_mask	= 0x3fffff,
 50	.count_unit		= 100000, /* 10 us */
 51};
 52
 53static struct meson_wdt_data meson8b_wdt_data = {
 54	.enable			= BIT(19),
 55	.terminal_count_mask	= 0xffff,
 56	.count_unit		= 7812, /* 128 us */
 57};
 58
 59struct meson_wdt_dev {
 60	struct watchdog_device wdt_dev;
 61	void __iomem *wdt_base;
 62	const struct meson_wdt_data *data;
 63};
 64
 65static int meson_wdt_restart(struct watchdog_device *wdt_dev,
 66			     unsigned long action, void *data)
 67{
 68	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
 69	u32 tc_reboot = MESON_WDT_DC_RESET;
 70
 71	tc_reboot |= meson_wdt->data->enable;
 72
 73	while (1) {
 74		writel(tc_reboot, meson_wdt->wdt_base + MESON_WDT_TC);
 75		mdelay(5);
 76	}
 77
 78	return 0;
 79}
 80
 81static int meson_wdt_ping(struct watchdog_device *wdt_dev)
 82{
 83	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
 84
 85	writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
 86
 87	return 0;
 88}
 89
 90static void meson_wdt_change_timeout(struct watchdog_device *wdt_dev,
 91				     unsigned int timeout)
 92{
 93	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
 94	u32 reg;
 95
 96	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
 97	reg &= ~meson_wdt->data->terminal_count_mask;
 98	reg |= MESON_SEC_TO_TC(timeout, meson_wdt->data->count_unit);
 99	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
100}
101
102static int meson_wdt_set_timeout(struct watchdog_device *wdt_dev,
103				 unsigned int timeout)
104{
105	wdt_dev->timeout = timeout;
106
107	meson_wdt_change_timeout(wdt_dev, timeout);
108	meson_wdt_ping(wdt_dev);
109
110	return 0;
111}
112
113static int meson_wdt_stop(struct watchdog_device *wdt_dev)
114{
115	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
116	u32 reg;
117
118	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
119	reg &= ~meson_wdt->data->enable;
120	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
121
122	return 0;
123}
124
125static int meson_wdt_start(struct watchdog_device *wdt_dev)
126{
127	struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
128	u32 reg;
129
130	meson_wdt_change_timeout(wdt_dev, meson_wdt->wdt_dev.timeout);
131	meson_wdt_ping(wdt_dev);
132
133	reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
134	reg |= meson_wdt->data->enable;
135	writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
136
137	return 0;
138}
139
140static const struct watchdog_info meson_wdt_info = {
141	.identity	= DRV_NAME,
142	.options	= WDIOF_SETTIMEOUT |
143			  WDIOF_KEEPALIVEPING |
144			  WDIOF_MAGICCLOSE,
145};
146
147static const struct watchdog_ops meson_wdt_ops = {
148	.owner		= THIS_MODULE,
149	.start		= meson_wdt_start,
150	.stop		= meson_wdt_stop,
151	.ping		= meson_wdt_ping,
152	.set_timeout	= meson_wdt_set_timeout,
153	.restart        = meson_wdt_restart,
154};
155
156static const struct of_device_id meson_wdt_dt_ids[] = {
157	{ .compatible = "amlogic,meson6-wdt", .data = &meson6_wdt_data },
158	{ .compatible = "amlogic,meson8b-wdt", .data = &meson8b_wdt_data },
159	{ /* sentinel */ }
160};
161MODULE_DEVICE_TABLE(of, meson_wdt_dt_ids);
162
163static int meson_wdt_probe(struct platform_device *pdev)
164{
165	struct resource *res;
166	struct meson_wdt_dev *meson_wdt;
167	const struct of_device_id *of_id;
168	int err;
169
170	meson_wdt = devm_kzalloc(&pdev->dev, sizeof(*meson_wdt), GFP_KERNEL);
171	if (!meson_wdt)
172		return -ENOMEM;
173
174	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
175	meson_wdt->wdt_base = devm_ioremap_resource(&pdev->dev, res);
176	if (IS_ERR(meson_wdt->wdt_base))
177		return PTR_ERR(meson_wdt->wdt_base);
178
179	of_id = of_match_device(meson_wdt_dt_ids, &pdev->dev);
180	if (!of_id) {
181		dev_err(&pdev->dev, "Unable to initialize WDT data\n");
182		return -ENODEV;
183	}
184	meson_wdt->data = of_id->data;
185
186	meson_wdt->wdt_dev.parent = &pdev->dev;
187	meson_wdt->wdt_dev.info = &meson_wdt_info;
188	meson_wdt->wdt_dev.ops = &meson_wdt_ops;
189	meson_wdt->wdt_dev.max_timeout =
190		meson_wdt->data->terminal_count_mask / meson_wdt->data->count_unit;
191	meson_wdt->wdt_dev.min_timeout = MESON_WDT_MIN_TIMEOUT;
192	meson_wdt->wdt_dev.timeout = min_t(unsigned int,
193					   MESON_WDT_TIMEOUT,
194					   meson_wdt->wdt_dev.max_timeout);
195
196	watchdog_set_drvdata(&meson_wdt->wdt_dev, meson_wdt);
197
198	watchdog_init_timeout(&meson_wdt->wdt_dev, timeout, &pdev->dev);
199	watchdog_set_nowayout(&meson_wdt->wdt_dev, nowayout);
200	watchdog_set_restart_priority(&meson_wdt->wdt_dev, 128);
201
202	meson_wdt_stop(&meson_wdt->wdt_dev);
203
204	err = watchdog_register_device(&meson_wdt->wdt_dev);
205	if (err)
206		return err;
207
208	platform_set_drvdata(pdev, meson_wdt);
209
210	dev_info(&pdev->dev, "Watchdog enabled (timeout=%d sec, nowayout=%d)",
211		 meson_wdt->wdt_dev.timeout, nowayout);
212
213	return 0;
214}
215
216static int meson_wdt_remove(struct platform_device *pdev)
217{
218	struct meson_wdt_dev *meson_wdt = platform_get_drvdata(pdev);
219
220	watchdog_unregister_device(&meson_wdt->wdt_dev);
221
222	return 0;
223}
224
225static void meson_wdt_shutdown(struct platform_device *pdev)
226{
227	struct meson_wdt_dev *meson_wdt = platform_get_drvdata(pdev);
228
229	meson_wdt_stop(&meson_wdt->wdt_dev);
230}
231
232static struct platform_driver meson_wdt_driver = {
233	.probe		= meson_wdt_probe,
234	.remove		= meson_wdt_remove,
235	.shutdown	= meson_wdt_shutdown,
236	.driver		= {
237		.name		= DRV_NAME,
238		.of_match_table	= meson_wdt_dt_ids,
239	},
240};
241
242module_platform_driver(meson_wdt_driver);
243
244module_param(timeout, uint, 0);
245MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
246
247module_param(nowayout, bool, 0);
248MODULE_PARM_DESC(nowayout,
249		 "Watchdog cannot be stopped once started (default="
250		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
251
252MODULE_LICENSE("GPL");
253MODULE_AUTHOR("Carlo Caione <carlo@caione.org>");
254MODULE_DESCRIPTION("Meson Watchdog Timer Driver");