1 /*
2  *  MEN 14F021P00 Board Management Controller (BMC) Watchdog Driver.
3  *
4  *  Copyright (C) 2014 MEN Mikro Elektronik Nuernberg GmbH
5  *
6  *  This program is free software; you can redistribute  it and/or modify it
7  *  under  the terms of  the GNU General  Public License as published by the
8  *  Free Software Foundation;  either version 2 of the  License, or (at your
9  *  option) any later version.
10  */
11 
12 #include <linux/kernel.h>
13 #include <linux/device.h>
14 #include <linux/module.h>
15 #include <linux/watchdog.h>
16 #include <linux/platform_device.h>
17 #include <linux/i2c.h>
18 
19 #define DEVNAME "menf21bmc_wdt"
20 
21 #define BMC_CMD_WD_ON		0x11
22 #define BMC_CMD_WD_OFF		0x12
23 #define BMC_CMD_WD_TRIG		0x13
24 #define BMC_CMD_WD_TIME		0x14
25 #define BMC_CMD_WD_STATE	0x17
26 #define BMC_WD_OFF_VAL		0x69
27 #define BMC_CMD_RST_RSN		0x92
28 
29 #define BMC_WD_TIMEOUT_MIN	1	/* in sec */
30 #define BMC_WD_TIMEOUT_MAX	6553	/* in sec */
31 
32 static bool nowayout = WATCHDOG_NOWAYOUT;
33 module_param(nowayout, bool, 0);
34 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
35 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
36 
37 struct menf21bmc_wdt {
38 	struct watchdog_device wdt;
39 	struct i2c_client *i2c_client;
40 };
41 
42 static int menf21bmc_wdt_set_bootstatus(struct menf21bmc_wdt *data)
43 {
44 	int rst_rsn;
45 
46 	rst_rsn = i2c_smbus_read_byte_data(data->i2c_client, BMC_CMD_RST_RSN);
47 	if (rst_rsn < 0)
48 		return rst_rsn;
49 
50 	if (rst_rsn == 0x02)
51 		data->wdt.bootstatus |= WDIOF_CARDRESET;
52 	else if (rst_rsn == 0x05)
53 		data->wdt.bootstatus |= WDIOF_EXTERN1;
54 	else if (rst_rsn == 0x06)
55 		data->wdt.bootstatus |= WDIOF_EXTERN2;
56 	else if (rst_rsn == 0x0A)
57 		data->wdt.bootstatus |= WDIOF_POWERUNDER;
58 
59 	return 0;
60 }
61 
62 static int menf21bmc_wdt_start(struct watchdog_device *wdt)
63 {
64 	struct menf21bmc_wdt *drv_data = watchdog_get_drvdata(wdt);
65 
66 	return i2c_smbus_write_byte(drv_data->i2c_client, BMC_CMD_WD_ON);
67 }
68 
69 static int menf21bmc_wdt_stop(struct watchdog_device *wdt)
70 {
71 	struct menf21bmc_wdt *drv_data = watchdog_get_drvdata(wdt);
72 
73 	return i2c_smbus_write_byte_data(drv_data->i2c_client,
74 					 BMC_CMD_WD_OFF, BMC_WD_OFF_VAL);
75 }
76 
77 static int
78 menf21bmc_wdt_settimeout(struct watchdog_device *wdt, unsigned int timeout)
79 {
80 	int ret;
81 	struct menf21bmc_wdt *drv_data = watchdog_get_drvdata(wdt);
82 
83 	/*
84 	 *  BMC Watchdog does have a resolution of 100ms.
85 	 *  Watchdog API defines the timeout in seconds, so we have to
86 	 *  multiply the value.
87 	 */
88 	ret = i2c_smbus_write_word_data(drv_data->i2c_client,
89 					BMC_CMD_WD_TIME, timeout * 10);
90 	if (ret < 0)
91 		return ret;
92 
93 	wdt->timeout = timeout;
94 
95 	return 0;
96 }
97 
98 static int menf21bmc_wdt_ping(struct watchdog_device *wdt)
99 {
100 	struct menf21bmc_wdt *drv_data = watchdog_get_drvdata(wdt);
101 
102 	return i2c_smbus_write_byte(drv_data->i2c_client, BMC_CMD_WD_TRIG);
103 }
104 
105 static const struct watchdog_info menf21bmc_wdt_info = {
106 	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
107 	.identity = DEVNAME,
108 };
109 
110 static const struct watchdog_ops menf21bmc_wdt_ops = {
111 	.owner		= THIS_MODULE,
112 	.start		= menf21bmc_wdt_start,
113 	.stop		= menf21bmc_wdt_stop,
114 	.ping		= menf21bmc_wdt_ping,
115 	.set_timeout	= menf21bmc_wdt_settimeout,
116 };
117 
118 static int menf21bmc_wdt_probe(struct platform_device *pdev)
119 {
120 	int ret, bmc_timeout;
121 	struct menf21bmc_wdt *drv_data;
122 	struct i2c_client *i2c_client = to_i2c_client(pdev->dev.parent);
123 
124 	drv_data = devm_kzalloc(&pdev->dev,
125 				sizeof(struct menf21bmc_wdt), GFP_KERNEL);
126 	if (!drv_data)
127 		return -ENOMEM;
128 
129 	drv_data->wdt.ops = &menf21bmc_wdt_ops;
130 	drv_data->wdt.info = &menf21bmc_wdt_info;
131 	drv_data->wdt.min_timeout = BMC_WD_TIMEOUT_MIN;
132 	drv_data->wdt.max_timeout = BMC_WD_TIMEOUT_MAX;
133 	drv_data->i2c_client = i2c_client;
134 
135 	/*
136 	 * Get the current wdt timeout value from the BMC because
137 	 * the BMC will save the value set before if the system restarts.
138 	 */
139 	bmc_timeout = i2c_smbus_read_word_data(drv_data->i2c_client,
140 					       BMC_CMD_WD_TIME);
141 	if (bmc_timeout < 0) {
142 		dev_err(&pdev->dev, "failed to get current WDT timeout\n");
143 		return bmc_timeout;
144 	}
145 
146 	watchdog_init_timeout(&drv_data->wdt, bmc_timeout / 10, &pdev->dev);
147 	watchdog_set_nowayout(&drv_data->wdt, nowayout);
148 	watchdog_set_drvdata(&drv_data->wdt, drv_data);
149 	platform_set_drvdata(pdev, drv_data);
150 
151 	ret = menf21bmc_wdt_set_bootstatus(drv_data);
152 	if (ret < 0) {
153 		dev_err(&pdev->dev, "failed to set Watchdog bootstatus\n");
154 		return ret;
155 	}
156 
157 	ret = watchdog_register_device(&drv_data->wdt);
158 	if (ret) {
159 		dev_err(&pdev->dev, "failed to register Watchdog device\n");
160 		return ret;
161 	}
162 
163 	dev_info(&pdev->dev, "MEN 14F021P00 BMC Watchdog device enabled\n");
164 
165 	return 0;
166 }
167 
168 static int menf21bmc_wdt_remove(struct platform_device *pdev)
169 {
170 	struct menf21bmc_wdt *drv_data = platform_get_drvdata(pdev);
171 
172 	dev_warn(&pdev->dev,
173 		 "Unregister MEN 14F021P00 BMC Watchdog device, board may reset\n");
174 
175 	watchdog_unregister_device(&drv_data->wdt);
176 
177 	return 0;
178 }
179 
180 static void menf21bmc_wdt_shutdown(struct platform_device *pdev)
181 {
182 	struct menf21bmc_wdt *drv_data = platform_get_drvdata(pdev);
183 
184 	i2c_smbus_write_word_data(drv_data->i2c_client,
185 				  BMC_CMD_WD_OFF, BMC_WD_OFF_VAL);
186 }
187 
188 static struct  platform_driver menf21bmc_wdt = {
189 	.driver		= {
190 		.name	= DEVNAME,
191 	},
192 	.probe		= menf21bmc_wdt_probe,
193 	.remove		= menf21bmc_wdt_remove,
194 	.shutdown	= menf21bmc_wdt_shutdown,
195 };
196 
197 module_platform_driver(menf21bmc_wdt);
198 
199 MODULE_DESCRIPTION("MEN 14F021P00 BMC Watchdog driver");
200 MODULE_AUTHOR("Andreas Werner <andreas.werner@men.de>");
201 MODULE_LICENSE("GPL v2");
202 MODULE_ALIAS("platform:menf21bmc_wdt");
203