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 
28 static bool nowayout = WATCHDOG_NOWAYOUT;
29 module_param(nowayout, bool, 0);
30 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
31 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
32 
33 struct menf21bmc_wdt {
34 	struct watchdog_device wdt;
35 	struct i2c_client *i2c_client;
36 };
37 
38 static 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 
58 static 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 
65 static 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 
73 static int
74 menf21bmc_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 
94 static 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 
101 static const struct watchdog_info menf21bmc_wdt_info = {
102 	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
103 	.identity = DEVNAME,
104 };
105 
106 static 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 
114 static 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 		dev_err(dev, "failed to register Watchdog device\n");
157 		return ret;
158 	}
159 
160 	dev_info(dev, "MEN 14F021P00 BMC Watchdog device enabled\n");
161 
162 	return 0;
163 }
164 
165 static void menf21bmc_wdt_shutdown(struct platform_device *pdev)
166 {
167 	struct menf21bmc_wdt *drv_data = platform_get_drvdata(pdev);
168 
169 	i2c_smbus_write_word_data(drv_data->i2c_client,
170 				  BMC_CMD_WD_OFF, BMC_WD_OFF_VAL);
171 }
172 
173 static struct  platform_driver menf21bmc_wdt = {
174 	.driver		= {
175 		.name	= DEVNAME,
176 	},
177 	.probe		= menf21bmc_wdt_probe,
178 	.shutdown	= menf21bmc_wdt_shutdown,
179 };
180 
181 module_platform_driver(menf21bmc_wdt);
182 
183 MODULE_DESCRIPTION("MEN 14F021P00 BMC Watchdog driver");
184 MODULE_AUTHOR("Andreas Werner <andreas.werner@men.de>");
185 MODULE_LICENSE("GPL v2");
186 MODULE_ALIAS("platform:menf21bmc_wdt");
187