1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *  MEN 14F021P00 Board Management Controller (BMC) Watchdog Driver.
4 *
5 *  Copyright (C) 2014 MEN Mikro Elektronik Nuernberg GmbH
6 */
7
8#include <linux/kernel.h>
9#include <linux/device.h>
10#include <linux/module.h>
11#include <linux/watchdog.h>
12#include <linux/platform_device.h>
13#include <linux/i2c.h>
14
15#define DEVNAME "menf21bmc_wdt"
16
17#define BMC_CMD_WD_ON		0x11
18#define BMC_CMD_WD_OFF		0x12
19#define BMC_CMD_WD_TRIG		0x13
20#define BMC_CMD_WD_TIME		0x14
21#define BMC_CMD_WD_STATE	0x17
22#define BMC_WD_OFF_VAL		0x69
23#define BMC_CMD_RST_RSN		0x92
24
25#define BMC_WD_TIMEOUT_MIN	1	/* in sec */
26#define BMC_WD_TIMEOUT_MAX	6553	/* in sec */
27
28static bool nowayout = WATCHDOG_NOWAYOUT;
29module_param(nowayout, bool, 0);
30MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
31				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
32
33struct menf21bmc_wdt {
34	struct watchdog_device wdt;
35	struct i2c_client *i2c_client;
36};
37
38static int menf21bmc_wdt_set_bootstatus(struct menf21bmc_wdt *data)
39{
40	int rst_rsn;
41
42	rst_rsn = i2c_smbus_read_byte_data(data->i2c_client, BMC_CMD_RST_RSN);
43	if (rst_rsn < 0)
44		return rst_rsn;
45
46	if (rst_rsn == 0x02)
47		data->wdt.bootstatus |= WDIOF_CARDRESET;
48	else if (rst_rsn == 0x05)
49		data->wdt.bootstatus |= WDIOF_EXTERN1;
50	else if (rst_rsn == 0x06)
51		data->wdt.bootstatus |= WDIOF_EXTERN2;
52	else if (rst_rsn == 0x0A)
53		data->wdt.bootstatus |= WDIOF_POWERUNDER;
54
55	return 0;
56}
57
58static int menf21bmc_wdt_start(struct watchdog_device *wdt)
59{
60	struct menf21bmc_wdt *drv_data = watchdog_get_drvdata(wdt);
61
62	return i2c_smbus_write_byte(drv_data->i2c_client, BMC_CMD_WD_ON);
63}
64
65static int menf21bmc_wdt_stop(struct watchdog_device *wdt)
66{
67	struct menf21bmc_wdt *drv_data = watchdog_get_drvdata(wdt);
68
69	return i2c_smbus_write_byte_data(drv_data->i2c_client,
70					 BMC_CMD_WD_OFF, BMC_WD_OFF_VAL);
71}
72
73static int
74menf21bmc_wdt_settimeout(struct watchdog_device *wdt, unsigned int timeout)
75{
76	int ret;
77	struct menf21bmc_wdt *drv_data = watchdog_get_drvdata(wdt);
78
79	/*
80	 *  BMC Watchdog does have a resolution of 100ms.
81	 *  Watchdog API defines the timeout in seconds, so we have to
82	 *  multiply the value.
83	 */
84	ret = i2c_smbus_write_word_data(drv_data->i2c_client,
85					BMC_CMD_WD_TIME, timeout * 10);
86	if (ret < 0)
87		return ret;
88
89	wdt->timeout = timeout;
90
91	return 0;
92}
93
94static int menf21bmc_wdt_ping(struct watchdog_device *wdt)
95{
96	struct menf21bmc_wdt *drv_data = watchdog_get_drvdata(wdt);
97
98	return i2c_smbus_write_byte(drv_data->i2c_client, BMC_CMD_WD_TRIG);
99}
100
101static const struct watchdog_info menf21bmc_wdt_info = {
102	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
103	.identity = DEVNAME,
104};
105
106static const struct watchdog_ops menf21bmc_wdt_ops = {
107	.owner		= THIS_MODULE,
108	.start		= menf21bmc_wdt_start,
109	.stop		= menf21bmc_wdt_stop,
110	.ping		= menf21bmc_wdt_ping,
111	.set_timeout	= menf21bmc_wdt_settimeout,
112};
113
114static int menf21bmc_wdt_probe(struct platform_device *pdev)
115{
116	struct device *dev = &pdev->dev;
117	int ret, bmc_timeout;
118	struct menf21bmc_wdt *drv_data;
119	struct i2c_client *i2c_client = to_i2c_client(dev->parent);
120
121	drv_data = devm_kzalloc(dev, sizeof(struct menf21bmc_wdt), GFP_KERNEL);
122	if (!drv_data)
123		return -ENOMEM;
124
125	drv_data->wdt.ops = &menf21bmc_wdt_ops;
126	drv_data->wdt.info = &menf21bmc_wdt_info;
127	drv_data->wdt.min_timeout = BMC_WD_TIMEOUT_MIN;
128	drv_data->wdt.max_timeout = BMC_WD_TIMEOUT_MAX;
129	drv_data->wdt.parent = dev;
130	drv_data->i2c_client = i2c_client;
131
132	/*
133	 * Get the current wdt timeout value from the BMC because
134	 * the BMC will save the value set before if the system restarts.
135	 */
136	bmc_timeout = i2c_smbus_read_word_data(drv_data->i2c_client,
137					       BMC_CMD_WD_TIME);
138	if (bmc_timeout < 0) {
139		dev_err(dev, "failed to get current WDT timeout\n");
140		return bmc_timeout;
141	}
142
143	watchdog_init_timeout(&drv_data->wdt, bmc_timeout / 10, dev);
144	watchdog_set_nowayout(&drv_data->wdt, nowayout);
145	watchdog_set_drvdata(&drv_data->wdt, drv_data);
146	platform_set_drvdata(pdev, drv_data);
147
148	ret = menf21bmc_wdt_set_bootstatus(drv_data);
149	if (ret < 0) {
150		dev_err(dev, "failed to set Watchdog bootstatus\n");
151		return ret;
152	}
153
154	ret = devm_watchdog_register_device(dev, &drv_data->wdt);
155	if (ret)
156		return ret;
157
158	dev_info(dev, "MEN 14F021P00 BMC Watchdog device enabled\n");
159
160	return 0;
161}
162
163static void menf21bmc_wdt_shutdown(struct platform_device *pdev)
164{
165	struct menf21bmc_wdt *drv_data = platform_get_drvdata(pdev);
166
167	i2c_smbus_write_word_data(drv_data->i2c_client,
168				  BMC_CMD_WD_OFF, BMC_WD_OFF_VAL);
169}
170
171static struct  platform_driver menf21bmc_wdt = {
172	.driver		= {
173		.name	= DEVNAME,
174	},
175	.probe		= menf21bmc_wdt_probe,
176	.shutdown	= menf21bmc_wdt_shutdown,
177};
178
179module_platform_driver(menf21bmc_wdt);
180
181MODULE_DESCRIPTION("MEN 14F021P00 BMC Watchdog driver");
182MODULE_AUTHOR("Andreas Werner <andreas.werner@men.de>");
183MODULE_LICENSE("GPL v2");
184MODULE_ALIAS("platform:menf21bmc_wdt");
185