1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Watchdog driver for the A21 VME CPU Boards
4 *
5 * Copyright (C) 2013 MEN Mikro Elektronik Nuernberg GmbH
6 *
7 */
8#include <linux/module.h>
9#include <linux/moduleparam.h>
10#include <linux/types.h>
11#include <linux/kernel.h>
12#include <linux/slab.h>
13#include <linux/platform_device.h>
14#include <linux/watchdog.h>
15#include <linux/uaccess.h>
16#include <linux/gpio/consumer.h>
17#include <linux/delay.h>
18#include <linux/bitops.h>
19#include <linux/of.h>
20
21#define NUM_GPIOS 6
22
23enum a21_wdt_gpios {
24	GPIO_WD_ENAB,
25	GPIO_WD_FAST,
26	GPIO_WD_TRIG,
27	GPIO_WD_RST0,
28	GPIO_WD_RST1,
29	GPIO_WD_RST2,
30};
31
32struct a21_wdt_drv {
33	struct watchdog_device wdt;
34	struct gpio_desc *gpios[NUM_GPIOS];
35};
36
37static bool nowayout = WATCHDOG_NOWAYOUT;
38module_param(nowayout, bool, 0);
39MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
40			    __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
41
42static unsigned int a21_wdt_get_bootstatus(struct a21_wdt_drv *drv)
43{
44	int reset = 0;
45
46	reset |= gpiod_get_value(drv->gpios[GPIO_WD_RST0]) ? (1 << 0) : 0;
47	reset |= gpiod_get_value(drv->gpios[GPIO_WD_RST1]) ? (1 << 1) : 0;
48	reset |= gpiod_get_value(drv->gpios[GPIO_WD_RST2]) ? (1 << 2) : 0;
49
50	return reset;
51}
52
53static int a21_wdt_start(struct watchdog_device *wdt)
54{
55	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
56
57	gpiod_set_value(drv->gpios[GPIO_WD_ENAB], 1);
58
59	return 0;
60}
61
62static int a21_wdt_stop(struct watchdog_device *wdt)
63{
64	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
65
66	gpiod_set_value(drv->gpios[GPIO_WD_ENAB], 0);
67
68	return 0;
69}
70
71static int a21_wdt_ping(struct watchdog_device *wdt)
72{
73	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
74
75	gpiod_set_value(drv->gpios[GPIO_WD_TRIG], 0);
76	ndelay(10);
77	gpiod_set_value(drv->gpios[GPIO_WD_TRIG], 1);
78
79	return 0;
80}
81
82static int a21_wdt_set_timeout(struct watchdog_device *wdt,
83			       unsigned int timeout)
84{
85	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
86
87	if (timeout != 1 && timeout != 30) {
88		dev_err(wdt->parent, "Only 1 and 30 allowed as timeout\n");
89		return -EINVAL;
90	}
91
92	if (timeout == 30 && wdt->timeout == 1) {
93		dev_err(wdt->parent,
94			"Transition from fast to slow mode not allowed\n");
95		return -EINVAL;
96	}
97
98	if (timeout == 1)
99		gpiod_set_value(drv->gpios[GPIO_WD_FAST], 1);
100	else
101		gpiod_set_value(drv->gpios[GPIO_WD_FAST], 0);
102
103	wdt->timeout = timeout;
104
105	return 0;
106}
107
108static const struct watchdog_info a21_wdt_info = {
109	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
110	.identity = "MEN A21 Watchdog",
111};
112
113static const struct watchdog_ops a21_wdt_ops = {
114	.owner = THIS_MODULE,
115	.start = a21_wdt_start,
116	.stop = a21_wdt_stop,
117	.ping = a21_wdt_ping,
118	.set_timeout = a21_wdt_set_timeout,
119};
120
121static struct watchdog_device a21_wdt = {
122	.info = &a21_wdt_info,
123	.ops = &a21_wdt_ops,
124	.min_timeout = 1,
125	.max_timeout = 30,
126};
127
128static int a21_wdt_probe(struct platform_device *pdev)
129{
130	struct device *dev = &pdev->dev;
131	struct a21_wdt_drv *drv;
132	unsigned int reset = 0;
133	int num_gpios;
134	int ret;
135	int i;
136
137	drv = devm_kzalloc(dev, sizeof(struct a21_wdt_drv), GFP_KERNEL);
138	if (!drv)
139		return -ENOMEM;
140
141	num_gpios = gpiod_count(dev, NULL);
142	if (num_gpios != NUM_GPIOS) {
143		dev_err(dev, "gpios DT property wrong, got %d want %d",
144			num_gpios, NUM_GPIOS);
145		return -ENODEV;
146	}
147
148	/* Request the used GPIOs */
149	for (i = 0; i < num_gpios; i++) {
150		enum gpiod_flags gflags;
151
152		if (i < GPIO_WD_RST0)
153			gflags = GPIOD_ASIS;
154		else
155			gflags = GPIOD_IN;
156		drv->gpios[i] = devm_gpiod_get_index(dev, NULL, i, gflags);
157		if (IS_ERR(drv->gpios[i]))
158			return PTR_ERR(drv->gpios[i]);
159
160		gpiod_set_consumer_name(drv->gpios[i], "MEN A21 Watchdog");
161
162		/*
163		 * Retrieve the initial value from the GPIOs that should be
164		 * output, then set up the line as output with that value.
165		 */
166		if (i < GPIO_WD_RST0) {
167			int val;
168
169			val = gpiod_get_value(drv->gpios[i]);
170			gpiod_direction_output(drv->gpios[i], val);
171		}
172	}
173
174	watchdog_init_timeout(&a21_wdt, 30, dev);
175	watchdog_set_nowayout(&a21_wdt, nowayout);
176	watchdog_set_drvdata(&a21_wdt, drv);
177	a21_wdt.parent = dev;
178
179	reset = a21_wdt_get_bootstatus(drv);
180	if (reset == 2)
181		a21_wdt.bootstatus |= WDIOF_EXTERN1;
182	else if (reset == 4)
183		a21_wdt.bootstatus |= WDIOF_CARDRESET;
184	else if (reset == 5)
185		a21_wdt.bootstatus |= WDIOF_POWERUNDER;
186	else if (reset == 7)
187		a21_wdt.bootstatus |= WDIOF_EXTERN2;
188
189	drv->wdt = a21_wdt;
190	dev_set_drvdata(dev, drv);
191
192	ret = devm_watchdog_register_device(dev, &a21_wdt);
193	if (ret)
194		return ret;
195
196	dev_info(dev, "MEN A21 watchdog timer driver enabled\n");
197
198	return 0;
199}
200
201static void a21_wdt_shutdown(struct platform_device *pdev)
202{
203	struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
204
205	gpiod_set_value(drv->gpios[GPIO_WD_ENAB], 0);
206}
207
208static const struct of_device_id a21_wdt_ids[] = {
209	{ .compatible = "men,a021-wdt" },
210	{ },
211};
212MODULE_DEVICE_TABLE(of, a21_wdt_ids);
213
214static struct platform_driver a21_wdt_driver = {
215	.probe = a21_wdt_probe,
216	.shutdown = a21_wdt_shutdown,
217	.driver = {
218		.name = "a21-watchdog",
219		.of_match_table = a21_wdt_ids,
220	},
221};
222
223module_platform_driver(a21_wdt_driver);
224
225MODULE_AUTHOR("MEN Mikro Elektronik");
226MODULE_DESCRIPTION("MEN A21 Watchdog");
227MODULE_LICENSE("GPL");
228MODULE_ALIAS("platform:a21-watchdog");
229