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
 32static bool nowayout = WATCHDOG_NOWAYOUT;
 33module_param(nowayout, bool, 0);
 34MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 35				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 36
 37struct menf21bmc_wdt {
 38	struct watchdog_device wdt;
 39	struct i2c_client *i2c_client;
 40};
 41
 42static 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
 62static 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
 69static 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
 77static int
 78menf21bmc_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
 98static 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
105static const struct watchdog_info menf21bmc_wdt_info = {
106	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
107	.identity = DEVNAME,
108};
109
110static 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
118static 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->wdt.parent = &pdev->dev;
134	drv_data->i2c_client = i2c_client;
135
136	/*
137	 * Get the current wdt timeout value from the BMC because
138	 * the BMC will save the value set before if the system restarts.
139	 */
140	bmc_timeout = i2c_smbus_read_word_data(drv_data->i2c_client,
141					       BMC_CMD_WD_TIME);
142	if (bmc_timeout < 0) {
143		dev_err(&pdev->dev, "failed to get current WDT timeout\n");
144		return bmc_timeout;
145	}
146
147	watchdog_init_timeout(&drv_data->wdt, bmc_timeout / 10, &pdev->dev);
148	watchdog_set_nowayout(&drv_data->wdt, nowayout);
149	watchdog_set_drvdata(&drv_data->wdt, drv_data);
150	platform_set_drvdata(pdev, drv_data);
151
152	ret = menf21bmc_wdt_set_bootstatus(drv_data);
153	if (ret < 0) {
154		dev_err(&pdev->dev, "failed to set Watchdog bootstatus\n");
155		return ret;
156	}
157
158	ret = watchdog_register_device(&drv_data->wdt);
159	if (ret) {
160		dev_err(&pdev->dev, "failed to register Watchdog device\n");
161		return ret;
162	}
163
164	dev_info(&pdev->dev, "MEN 14F021P00 BMC Watchdog device enabled\n");
165
166	return 0;
167}
168
169static int menf21bmc_wdt_remove(struct platform_device *pdev)
170{
171	struct menf21bmc_wdt *drv_data = platform_get_drvdata(pdev);
172
173	dev_warn(&pdev->dev,
174		 "Unregister MEN 14F021P00 BMC Watchdog device, board may reset\n");
175
176	watchdog_unregister_device(&drv_data->wdt);
177
178	return 0;
179}
180
181static void menf21bmc_wdt_shutdown(struct platform_device *pdev)
182{
183	struct menf21bmc_wdt *drv_data = platform_get_drvdata(pdev);
184
185	i2c_smbus_write_word_data(drv_data->i2c_client,
186				  BMC_CMD_WD_OFF, BMC_WD_OFF_VAL);
187}
188
189static struct  platform_driver menf21bmc_wdt = {
190	.driver		= {
191		.name	= DEVNAME,
192	},
193	.probe		= menf21bmc_wdt_probe,
194	.remove		= menf21bmc_wdt_remove,
195	.shutdown	= menf21bmc_wdt_shutdown,
196};
197
198module_platform_driver(menf21bmc_wdt);
199
200MODULE_DESCRIPTION("MEN 14F021P00 BMC Watchdog driver");
201MODULE_AUTHOR("Andreas Werner <andreas.werner@men.de>");
202MODULE_LICENSE("GPL v2");
203MODULE_ALIAS("platform:menf21bmc_wdt");