1/*
  2 * Watchdog driver for the A21 VME CPU Boards
  3 *
  4 * Copyright (C) 2013 MEN Mikro Elektronik Nuernberg GmbH
  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
  9 */
 10#include <linux/module.h>
 11#include <linux/moduleparam.h>
 12#include <linux/types.h>
 13#include <linux/kernel.h>
 14#include <linux/slab.h>
 15#include <linux/platform_device.h>
 16#include <linux/watchdog.h>
 17#include <linux/uaccess.h>
 18#include <linux/gpio.h>
 19#include <linux/of_gpio.h>
 20#include <linux/delay.h>
 21#include <linux/bitops.h>
 22
 23#define NUM_GPIOS 6
 24
 25enum a21_wdt_gpios {
 26	GPIO_WD_ENAB,
 27	GPIO_WD_FAST,
 28	GPIO_WD_TRIG,
 29	GPIO_WD_RST0,
 30	GPIO_WD_RST1,
 31	GPIO_WD_RST2,
 32};
 33
 34struct a21_wdt_drv {
 35	struct watchdog_device wdt;
 36	struct mutex lock;
 37	unsigned gpios[NUM_GPIOS];
 38};
 39
 40static bool nowayout = WATCHDOG_NOWAYOUT;
 41module_param(nowayout, bool, 0);
 42MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 43			    __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 44
 45static unsigned int a21_wdt_get_bootstatus(struct a21_wdt_drv *drv)
 46{
 47	int reset = 0;
 48
 49	reset |= gpio_get_value(drv->gpios[GPIO_WD_RST0]) ? (1 << 0) : 0;
 50	reset |= gpio_get_value(drv->gpios[GPIO_WD_RST1]) ? (1 << 1) : 0;
 51	reset |= gpio_get_value(drv->gpios[GPIO_WD_RST2]) ? (1 << 2) : 0;
 52
 53	return reset;
 54}
 55
 56static int a21_wdt_start(struct watchdog_device *wdt)
 57{
 58	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
 59
 60	mutex_lock(&drv->lock);
 61
 62	gpio_set_value(drv->gpios[GPIO_WD_ENAB], 1);
 63
 64	mutex_unlock(&drv->lock);
 65
 66	return 0;
 67}
 68
 69static int a21_wdt_stop(struct watchdog_device *wdt)
 70{
 71	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
 72
 73	mutex_lock(&drv->lock);
 74
 75	gpio_set_value(drv->gpios[GPIO_WD_ENAB], 0);
 76
 77	mutex_unlock(&drv->lock);
 78
 79	return 0;
 80}
 81
 82static int a21_wdt_ping(struct watchdog_device *wdt)
 83{
 84	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
 85
 86	mutex_lock(&drv->lock);
 87
 88	gpio_set_value(drv->gpios[GPIO_WD_TRIG], 0);
 89	ndelay(10);
 90	gpio_set_value(drv->gpios[GPIO_WD_TRIG], 1);
 91
 92	mutex_unlock(&drv->lock);
 93
 94	return 0;
 95}
 96
 97static int a21_wdt_set_timeout(struct watchdog_device *wdt,
 98			       unsigned int timeout)
 99{
100	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
101
102	if (timeout != 1 && timeout != 30) {
103		dev_err(wdt->parent, "Only 1 and 30 allowed as timeout\n");
104		return -EINVAL;
105	}
106
107	if (timeout == 30 && wdt->timeout == 1) {
108		dev_err(wdt->parent,
109			"Transition from fast to slow mode not allowed\n");
110		return -EINVAL;
111	}
112
113	mutex_lock(&drv->lock);
114
115	if (timeout == 1)
116		gpio_set_value(drv->gpios[GPIO_WD_FAST], 1);
117	else
118		gpio_set_value(drv->gpios[GPIO_WD_FAST], 0);
119
120	wdt->timeout = timeout;
121
122	mutex_unlock(&drv->lock);
123
124	return 0;
125}
126
127static const struct watchdog_info a21_wdt_info = {
128	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
129	.identity = "MEN A21 Watchdog",
130};
131
132static const struct watchdog_ops a21_wdt_ops = {
133	.owner = THIS_MODULE,
134	.start = a21_wdt_start,
135	.stop = a21_wdt_stop,
136	.ping = a21_wdt_ping,
137	.set_timeout = a21_wdt_set_timeout,
138};
139
140static struct watchdog_device a21_wdt = {
141	.info = &a21_wdt_info,
142	.ops = &a21_wdt_ops,
143	.min_timeout = 1,
144	.max_timeout = 30,
145};
146
147static int a21_wdt_probe(struct platform_device *pdev)
148{
149	struct device_node *node;
150	struct a21_wdt_drv *drv;
151	unsigned int reset = 0;
152	int num_gpios;
153	int ret;
154	int i;
155
156	drv = devm_kzalloc(&pdev->dev, sizeof(struct a21_wdt_drv), GFP_KERNEL);
157	if (!drv)
158		return -ENOMEM;
159
160	/* Fill GPIO pin array */
161	node = pdev->dev.of_node;
162
163	num_gpios = of_gpio_count(node);
164	if (num_gpios != NUM_GPIOS) {
165		dev_err(&pdev->dev, "gpios DT property wrong, got %d want %d",
166			num_gpios, NUM_GPIOS);
167		return -ENODEV;
168	}
169
170	for (i = 0; i < num_gpios; i++) {
171		int val;
172
173		val = of_get_gpio(node, i);
174		if (val < 0)
175			return val;
176
177		drv->gpios[i] = val;
178	}
179
180	/* Request the used GPIOs */
181	for (i = 0; i < num_gpios; i++) {
182		ret = devm_gpio_request(&pdev->dev, drv->gpios[i],
183					"MEN A21 Watchdog");
184		if (ret)
185			return ret;
186
187		if (i < GPIO_WD_RST0)
188			ret = gpio_direction_output(drv->gpios[i],
189						gpio_get_value(drv->gpios[i]));
190		else		/* GPIO_WD_RST[0..2] are inputs */
191			ret = gpio_direction_input(drv->gpios[i]);
192		if (ret)
193			return ret;
194	}
195
196	mutex_init(&drv->lock);
197	watchdog_init_timeout(&a21_wdt, 30, &pdev->dev);
198	watchdog_set_nowayout(&a21_wdt, nowayout);
199	watchdog_set_drvdata(&a21_wdt, drv);
200	a21_wdt.parent = &pdev->dev;
201
202	reset = a21_wdt_get_bootstatus(drv);
203	if (reset == 2)
204		a21_wdt.bootstatus |= WDIOF_EXTERN1;
205	else if (reset == 4)
206		a21_wdt.bootstatus |= WDIOF_CARDRESET;
207	else if (reset == 5)
208		a21_wdt.bootstatus |= WDIOF_POWERUNDER;
209	else if (reset == 7)
210		a21_wdt.bootstatus |= WDIOF_EXTERN2;
211
212	drv->wdt = a21_wdt;
213	dev_set_drvdata(&pdev->dev, drv);
214
215	ret = watchdog_register_device(&a21_wdt);
216	if (ret) {
217		dev_err(&pdev->dev, "Cannot register watchdog device\n");
218		goto err_register_wd;
219	}
220
221	dev_info(&pdev->dev, "MEN A21 watchdog timer driver enabled\n");
222
223	return 0;
224
225err_register_wd:
226	mutex_destroy(&drv->lock);
227
228	return ret;
229}
230
231static int a21_wdt_remove(struct platform_device *pdev)
232{
233	struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
234
235	dev_warn(&pdev->dev,
236		"Unregistering A21 watchdog driver, board may reboot\n");
237
238	watchdog_unregister_device(&drv->wdt);
239
240	mutex_destroy(&drv->lock);
241
242	return 0;
243}
244
245static void a21_wdt_shutdown(struct platform_device *pdev)
246{
247	struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
248
249	gpio_set_value(drv->gpios[GPIO_WD_ENAB], 0);
250}
251
252static const struct of_device_id a21_wdt_ids[] = {
253	{ .compatible = "men,a021-wdt" },
254	{ },
255};
256MODULE_DEVICE_TABLE(of, a21_wdt_ids);
257
258static struct platform_driver a21_wdt_driver = {
259	.probe = a21_wdt_probe,
260	.remove = a21_wdt_remove,
261	.shutdown = a21_wdt_shutdown,
262	.driver = {
263		.name = "a21-watchdog",
264		.of_match_table = a21_wdt_ids,
265	},
266};
267
268module_platform_driver(a21_wdt_driver);
269
270MODULE_AUTHOR("MEN Mikro Elektronik");
271MODULE_DESCRIPTION("MEN A21 Watchdog");
272MODULE_LICENSE("GPL");
273MODULE_ALIAS("platform:a21-watchdog");