hwmon: PMBus device driver

This driver adds support for hardware monitoring features of various PMBus
devices.
Signed-off-by: NGuenter Roeck <guenter.roeck@ericsson.com>
Acked-by: NJonathan Cameron <jic23@cam.ac.uk>

drivers/hwmon/Kconfig

@@ -756,6 +756,31 @@ config SENSORS_PCF8591
 	  These devices are hard to detect and rarely found on mainstream
 	  hardware.  If unsure, say N.
 
+config PMBUS
+	tristate "PMBus support"
+	depends on I2C && EXPERIMENTAL
+	default n
+	help
+	  Say yes here if you want to enable PMBus support.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called pmbus_core.
+
+if PMBUS
+
+config SENSORS_PMBUS
+	tristate "Generic PMBus devices"
+	default n
+	help
+	  If you say yes here you get hardware monitoring support for generic
+	  PMBus devices, including but not limited to BMR450, BMR451, BMR453,
+	  BMR454, and LTC2978.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called pmbus.
+
+endif # PMBUS
+
 config SENSORS_SHT15
 	tristate "Sensiron humidity and temperature sensors. SHT15 and compat."
 	depends on GENERIC_GPIO

drivers/hwmon/Makefile

@@ -114,6 +114,10 @@ obj-$(CONFIG_SENSORS_W83L786NG)	+= w83l786ng.o
 obj-$(CONFIG_SENSORS_WM831X)	+= wm831x-hwmon.o
 obj-$(CONFIG_SENSORS_WM8350)	+= wm8350-hwmon.o
 
+# PMBus drivers
+obj-$(CONFIG_PMBUS)		+= pmbus_core.o
+obj-$(CONFIG_SENSORS_PMBUS)	+= pmbus.o
+
 ifeq ($(CONFIG_HWMON_DEBUG_CHIP),y)
 EXTRA_CFLAGS += -DDEBUG
 endif

drivers/hwmon/pmbus.c

+/*
+ * Hardware monitoring driver for PMBus devices
+ *
+ * Copyright (c) 2010, 2011 Ericsson AB.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/i2c.h>
+#include "pmbus.h"
+
+/*
+ * Find sensor groups and status registers on each page.
+ */
+static void pmbus_find_sensor_groups(struct i2c_client *client,
+				     struct pmbus_driver_info *info)
+{
+	int page;
+
+	/* Sensors detected on page 0 only */
+	if (pmbus_check_word_register(client, 0, PMBUS_READ_VIN))
+		info->func[0] |= PMBUS_HAVE_VIN;
+	if (pmbus_check_word_register(client, 0, PMBUS_READ_VCAP))
+		info->func[0] |= PMBUS_HAVE_VCAP;
+	if (pmbus_check_word_register(client, 0, PMBUS_READ_IIN))
+		info->func[0] |= PMBUS_HAVE_IIN;
+	if (pmbus_check_word_register(client, 0, PMBUS_READ_PIN))
+		info->func[0] |= PMBUS_HAVE_PIN;
+	if (info->func[0]
+	    && pmbus_check_byte_register(client, 0, PMBUS_STATUS_INPUT))
+		info->func[0] |= PMBUS_HAVE_STATUS_INPUT;
+	if (pmbus_check_word_register(client, 0, PMBUS_READ_FAN_SPEED_1)) {
+		info->func[0] |= PMBUS_HAVE_FAN12;
+		if (pmbus_check_byte_register(client, 0, PMBUS_STATUS_FAN_12))
+			info->func[0] |= PMBUS_HAVE_STATUS_FAN12;
+	}
+	if (pmbus_check_word_register(client, 0, PMBUS_READ_FAN_SPEED_3)) {
+		info->func[0] |= PMBUS_HAVE_FAN34;
+		if (pmbus_check_byte_register(client, 0, PMBUS_STATUS_FAN_34))
+			info->func[0] |= PMBUS_HAVE_STATUS_FAN34;
+	}
+	if (pmbus_check_word_register(client, 0, PMBUS_READ_TEMPERATURE_1)) {
+		info->func[0] |= PMBUS_HAVE_TEMP;
+		if (pmbus_check_byte_register(client, 0,
+					      PMBUS_STATUS_TEMPERATURE))
+			info->func[0] |= PMBUS_HAVE_STATUS_TEMP;
+	}
+
+	/* Sensors detected on all pages */
+	for (page = 0; page < info->pages; page++) {
+		if (pmbus_check_word_register(client, page, PMBUS_READ_VOUT)) {
+			info->func[page] |= PMBUS_HAVE_VOUT;
+			if (pmbus_check_byte_register(client, page,
+						      PMBUS_STATUS_VOUT))
+				info->func[page] |= PMBUS_HAVE_STATUS_VOUT;
+		}
+		if (pmbus_check_word_register(client, page, PMBUS_READ_IOUT)) {
+			info->func[page] |= PMBUS_HAVE_IOUT;
+			if (pmbus_check_byte_register(client, 0,
+						      PMBUS_STATUS_IOUT))
+				info->func[page] |= PMBUS_HAVE_STATUS_IOUT;
+		}
+		if (pmbus_check_word_register(client, page, PMBUS_READ_POUT))
+			info->func[page] |= PMBUS_HAVE_POUT;
+	}
+}
+
+/*
+ * Identify chip parameters.
+ */
+static int pmbus_identify(struct i2c_client *client,
+			  struct pmbus_driver_info *info)
+{
+	if (!info->pages) {
+		/*
+		 * Check if the PAGE command is supported. If it is,
+		 * keep setting the page number until it fails or until the
+		 * maximum number of pages has been reached. Assume that
+		 * this is the number of pages supported by the chip.
+		 */
+		if (pmbus_check_byte_register(client, 0, PMBUS_PAGE)) {
+			int page;
+
+			for (page = 1; page < PMBUS_PAGES; page++) {
+				if (pmbus_set_page(client, page) < 0)
+					break;
+			}
+			pmbus_set_page(client, 0);
+			info->pages = page;
+		} else {
+			info->pages = 1;
+		}
+	}
+
+	/*
+	 * We should check if the COEFFICIENTS register is supported.
+	 * If it is, and the chip is configured for direct mode, we can read
+	 * the coefficients from the chip, one set per group of sensor
+	 * registers.
+	 *
+	 * To do this, we will need access to a chip which actually supports the
+	 * COEFFICIENTS command, since the command is too complex to implement
+	 * without testing it.
+	 */
+
+	/* Try to find sensor groups  */
+	pmbus_find_sensor_groups(client, info);
+
+	return 0;
+}
+
+static int pmbus_probe(struct i2c_client *client,
+		       const struct i2c_device_id *id)
+{
+	struct pmbus_driver_info *info;
+	int ret;
+
+	info = kzalloc(sizeof(struct pmbus_driver_info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	info->pages = id->driver_data;
+	info->identify = pmbus_identify;
+
+	ret = pmbus_do_probe(client, id, info);
+	if (ret < 0)
+		goto out;
+	return 0;
+
+out:
+	kfree(info);
+	return ret;
+}
+
+static int pmbus_remove(struct i2c_client *client)
+{
+	int ret;
+	const struct pmbus_driver_info *info;
+
+	info = pmbus_get_driver_info(client);
+	ret = pmbus_do_remove(client);
+	kfree(info);
+	return ret;
+}
+
+/*
+ * Use driver_data to set the number of pages supported by the chip.
+ */
+static const struct i2c_device_id pmbus_id[] = {
+	{"bmr450", 1},
+	{"bmr451", 1},
+	{"bmr453", 1},
+	{"bmr454", 1},
+	{"ltc2978", 8},
+	{"pmbus", 0},
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, pmbus_id);
+
+/* This is the driver that will be inserted */
+static struct i2c_driver pmbus_driver = {
+	.driver = {
+		   .name = "pmbus",
+		   },
+	.probe = pmbus_probe,
+	.remove = pmbus_remove,
+	.id_table = pmbus_id,
+};
+
+static int __init pmbus_init(void)
+{
+	return i2c_add_driver(&pmbus_driver);
+}
+
+static void __exit pmbus_exit(void)
+{
+	i2c_del_driver(&pmbus_driver);
+}
+
+MODULE_AUTHOR("Guenter Roeck");
+MODULE_DESCRIPTION("Generic PMBus driver");
+MODULE_LICENSE("GPL");
+module_init(pmbus_init);
+module_exit(pmbus_exit);

drivers/hwmon/pmbus.h

+/*
+ * pmbus.h - Common defines and structures for PMBus devices
+ *
+ * Copyright (c) 2010, 2011 Ericsson AB.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef PMBUS_H
+#define PMBUS_H
+
+/*
+ * Registers
+ */
+#define PMBUS_PAGE			0x00
+#define PMBUS_OPERATION			0x01
+#define PMBUS_ON_OFF_CONFIG		0x02
+#define PMBUS_CLEAR_FAULTS		0x03
+#define PMBUS_PHASE			0x04
+
+#define PMBUS_CAPABILITY		0x19
+#define PMBUS_QUERY			0x1A
+
+#define PMBUS_VOUT_MODE			0x20
+#define PMBUS_VOUT_COMMAND		0x21
+#define PMBUS_VOUT_TRIM			0x22
+#define PMBUS_VOUT_CAL_OFFSET		0x23
+#define PMBUS_VOUT_MAX			0x24
+#define PMBUS_VOUT_MARGIN_HIGH		0x25
+#define PMBUS_VOUT_MARGIN_LOW		0x26
+#define PMBUS_VOUT_TRANSITION_RATE	0x27
+#define PMBUS_VOUT_DROOP		0x28
+#define PMBUS_VOUT_SCALE_LOOP		0x29
+#define PMBUS_VOUT_SCALE_MONITOR	0x2A
+
+#define PMBUS_COEFFICIENTS		0x30
+#define PMBUS_POUT_MAX			0x31
+
+#define PMBUS_FAN_CONFIG_12		0x3A
+#define PMBUS_FAN_COMMAND_1		0x3B
+#define PMBUS_FAN_COMMAND_2		0x3C
+#define PMBUS_FAN_CONFIG_34		0x3D
+#define PMBUS_FAN_COMMAND_3		0x3E
+#define PMBUS_FAN_COMMAND_4		0x3F
+
+#define PMBUS_VOUT_OV_FAULT_LIMIT	0x40
+#define PMBUS_VOUT_OV_FAULT_RESPONSE	0x41
+#define PMBUS_VOUT_OV_WARN_LIMIT	0x42
+#define PMBUS_VOUT_UV_WARN_LIMIT	0x43
+#define PMBUS_VOUT_UV_FAULT_LIMIT	0x44
+#define PMBUS_VOUT_UV_FAULT_RESPONSE	0x45
+#define PMBUS_IOUT_OC_FAULT_LIMIT	0x46
+#define PMBUS_IOUT_OC_FAULT_RESPONSE	0x47
+#define PMBUS_IOUT_OC_LV_FAULT_LIMIT	0x48
+#define PMBUS_IOUT_OC_LV_FAULT_RESPONSE	0x49
+#define PMBUS_IOUT_OC_WARN_LIMIT	0x4A
+#define PMBUS_IOUT_UC_FAULT_LIMIT	0x4B
+#define PMBUS_IOUT_UC_FAULT_RESPONSE	0x4C
+
+#define PMBUS_OT_FAULT_LIMIT		0x4F
+#define PMBUS_OT_FAULT_RESPONSE		0x50
+#define PMBUS_OT_WARN_LIMIT		0x51
+#define PMBUS_UT_WARN_LIMIT		0x52
+#define PMBUS_UT_FAULT_LIMIT		0x53
+#define PMBUS_UT_FAULT_RESPONSE		0x54
+#define PMBUS_VIN_OV_FAULT_LIMIT	0x55
+#define PMBUS_VIN_OV_FAULT_RESPONSE	0x56
+#define PMBUS_VIN_OV_WARN_LIMIT		0x57
+#define PMBUS_VIN_UV_WARN_LIMIT		0x58
+#define PMBUS_VIN_UV_FAULT_LIMIT	0x59
+
+#define PMBUS_IIN_OC_FAULT_LIMIT	0x5B
+#define PMBUS_IIN_OC_WARN_LIMIT		0x5D
+
+#define PMBUS_POUT_OP_FAULT_LIMIT	0x68
+#define PMBUS_POUT_OP_WARN_LIMIT	0x6A
+#define PMBUS_PIN_OP_WARN_LIMIT		0x6B
+
+#define PMBUS_STATUS_BYTE		0x78
+#define PMBUS_STATUS_WORD		0x79
+#define PMBUS_STATUS_VOUT		0x7A
+#define PMBUS_STATUS_IOUT		0x7B
+#define PMBUS_STATUS_INPUT		0x7C
+#define PMBUS_STATUS_TEMPERATURE	0x7D
+#define PMBUS_STATUS_CML		0x7E
+#define PMBUS_STATUS_OTHER		0x7F
+#define PMBUS_STATUS_MFR_SPECIFIC	0x80
+#define PMBUS_STATUS_FAN_12		0x81
+#define PMBUS_STATUS_FAN_34		0x82
+
+#define PMBUS_READ_VIN			0x88
+#define PMBUS_READ_IIN			0x89
+#define PMBUS_READ_VCAP			0x8A
+#define PMBUS_READ_VOUT			0x8B
+#define PMBUS_READ_IOUT			0x8C
+#define PMBUS_READ_TEMPERATURE_1	0x8D
+#define PMBUS_READ_TEMPERATURE_2	0x8E
+#define PMBUS_READ_TEMPERATURE_3	0x8F
+#define PMBUS_READ_FAN_SPEED_1		0x90
+#define PMBUS_READ_FAN_SPEED_2		0x91
+#define PMBUS_READ_FAN_SPEED_3		0x92
+#define PMBUS_READ_FAN_SPEED_4		0x93
+#define PMBUS_READ_DUTY_CYCLE		0x94
+#define PMBUS_READ_FREQUENCY		0x95
+#define PMBUS_READ_POUT			0x96
+#define PMBUS_READ_PIN			0x97
+
+#define PMBUS_REVISION			0x98
+#define PMBUS_MFR_ID			0x99
+#define PMBUS_MFR_MODEL			0x9A
+#define PMBUS_MFR_REVISION		0x9B
+#define PMBUS_MFR_LOCATION		0x9C
+#define PMBUS_MFR_DATE			0x9D
+#define PMBUS_MFR_SERIAL		0x9E
+
+/*
+ * CAPABILITY
+ */
+#define PB_CAPABILITY_SMBALERT		(1<<4)
+#define PB_CAPABILITY_ERROR_CHECK	(1<<7)
+
+/*
+ * VOUT_MODE
+ */
+#define PB_VOUT_MODE_MODE_MASK		0xe0
+#define PB_VOUT_MODE_PARAM_MASK		0x1f
+
+#define PB_VOUT_MODE_LINEAR		0x00
+#define PB_VOUT_MODE_VID		0x20
+#define PB_VOUT_MODE_DIRECT		0x40
+
+/*
+ * Fan configuration
+ */
+#define PB_FAN_2_PULSE_MASK		((1 << 0) | (1 << 1))
+#define PB_FAN_2_RPM			(1 << 2)
+#define PB_FAN_2_INSTALLED		(1 << 3)
+#define PB_FAN_1_PULSE_MASK		((1 << 4) | (1 << 5))
+#define PB_FAN_1_RPM			(1 << 6)
+#define PB_FAN_1_INSTALLED		(1 << 7)
+
+/*
+ * STATUS_BYTE, STATUS_WORD (lower)
+ */
+#define PB_STATUS_NONE_ABOVE		(1<<0)
+#define PB_STATUS_CML			(1<<1)
+#define PB_STATUS_TEMPERATURE		(1<<2)
+#define PB_STATUS_VIN_UV		(1<<3)
+#define PB_STATUS_IOUT_OC		(1<<4)
+#define PB_STATUS_VOUT_OV		(1<<5)
+#define PB_STATUS_OFF			(1<<6)
+#define PB_STATUS_BUSY			(1<<7)
+
+/*
+ * STATUS_WORD (upper)
+ */
+#define PB_STATUS_UNKNOWN		(1<<8)
+#define PB_STATUS_OTHER			(1<<9)
+#define PB_STATUS_FANS			(1<<10)
+#define PB_STATUS_POWER_GOOD_N		(1<<11)
+#define PB_STATUS_WORD_MFR		(1<<12)
+#define PB_STATUS_INPUT			(1<<13)
+#define PB_STATUS_IOUT_POUT		(1<<14)
+#define PB_STATUS_VOUT			(1<<15)
+
+/*
+ * STATUS_IOUT
+ */
+#define PB_POUT_OP_WARNING		(1<<0)
+#define PB_POUT_OP_FAULT		(1<<1)
+#define PB_POWER_LIMITING		(1<<2)
+#define PB_CURRENT_SHARE_FAULT		(1<<3)
+#define PB_IOUT_UC_FAULT		(1<<4)
+#define PB_IOUT_OC_WARNING		(1<<5)
+#define PB_IOUT_OC_LV_FAULT		(1<<6)
+#define PB_IOUT_OC_FAULT		(1<<7)
+
+/*
+ * STATUS_VOUT, STATUS_INPUT
+ */
+#define PB_VOLTAGE_UV_FAULT		(1<<4)
+#define PB_VOLTAGE_UV_WARNING		(1<<5)
+#define PB_VOLTAGE_OV_WARNING		(1<<6)
+#define PB_VOLTAGE_OV_FAULT		(1<<7)
+
+/*
+ * STATUS_INPUT
+ */
+#define PB_PIN_OP_WARNING		(1<<0)
+#define PB_IIN_OC_WARNING		(1<<1)
+#define PB_IIN_OC_FAULT			(1<<2)
+
+/*
+ * STATUS_TEMPERATURE
+ */
+#define PB_TEMP_UT_FAULT		(1<<4)
+#define PB_TEMP_UT_WARNING		(1<<5)
+#define PB_TEMP_OT_WARNING		(1<<6)
+#define PB_TEMP_OT_FAULT		(1<<7)
+
+/*
+ * STATUS_FAN
+ */
+#define PB_FAN_AIRFLOW_WARNING		(1<<0)
+#define PB_FAN_AIRFLOW_FAULT		(1<<1)
+#define PB_FAN_FAN2_SPEED_OVERRIDE	(1<<2)
+#define PB_FAN_FAN1_SPEED_OVERRIDE	(1<<3)
+#define PB_FAN_FAN2_WARNING		(1<<4)
+#define PB_FAN_FAN1_WARNING		(1<<5)
+#define PB_FAN_FAN2_FAULT		(1<<6)
+#define PB_FAN_FAN1_FAULT		(1<<7)
+
+/*
+ * CML_FAULT_STATUS
+ */
+#define PB_CML_FAULT_OTHER_MEM_LOGIC	(1<<0)
+#define PB_CML_FAULT_OTHER_COMM		(1<<1)
+#define PB_CML_FAULT_PROCESSOR		(1<<3)
+#define PB_CML_FAULT_MEMORY		(1<<4)
+#define PB_CML_FAULT_PACKET_ERROR	(1<<5)
+#define PB_CML_FAULT_INVALID_DATA	(1<<6)
+#define PB_CML_FAULT_INVALID_COMMAND	(1<<7)
+
+enum pmbus_sensor_classes {
+	PSC_VOLTAGE_IN = 0,
+	PSC_VOLTAGE_OUT,
+	PSC_CURRENT_IN,
+	PSC_CURRENT_OUT,
+	PSC_POWER,
+	PSC_TEMPERATURE,
+	PSC_FAN,
+	PSC_NUM_CLASSES		/* Number of power sensor classes */
+};
+
+#define PMBUS_PAGES	32	/* Per PMBus specification */
+
+/* Functionality bit mask */
+#define PMBUS_HAVE_VIN		(1 << 0)
+#define PMBUS_HAVE_VCAP		(1 << 1)
+#define PMBUS_HAVE_VOUT		(1 << 2)
+#define PMBUS_HAVE_IIN		(1 << 3)
+#define PMBUS_HAVE_IOUT		(1 << 4)
+#define PMBUS_HAVE_PIN		(1 << 5)
+#define PMBUS_HAVE_POUT		(1 << 6)
+#define PMBUS_HAVE_FAN12	(1 << 7)
+#define PMBUS_HAVE_FAN34	(1 << 8)
+#define PMBUS_HAVE_TEMP		(1 << 9)
+#define PMBUS_HAVE_TEMP2	(1 << 10)
+#define PMBUS_HAVE_TEMP3	(1 << 11)
+#define PMBUS_HAVE_STATUS_VOUT	(1 << 12)
+#define PMBUS_HAVE_STATUS_IOUT	(1 << 13)
+#define PMBUS_HAVE_STATUS_INPUT	(1 << 14)
+#define PMBUS_HAVE_STATUS_TEMP	(1 << 15)
+#define PMBUS_HAVE_STATUS_FAN12	(1 << 16)
+#define PMBUS_HAVE_STATUS_FAN34	(1 << 17)
+
+struct pmbus_driver_info {
+	int pages;		/* Total number of pages */
+	bool direct[PSC_NUM_CLASSES];
+				/* true if device uses direct data format
+				   for the given sensor class */
+	/*
+	 * Support one set of coefficients for each sensor type
+	 * Used for chips providing data in direct mode.
+	 */
+	int m[PSC_NUM_CLASSES];	/* mantissa for direct data format */
+	int b[PSC_NUM_CLASSES];	/* offset */
+	int R[PSC_NUM_CLASSES];	/* exponent */
+
+	u32 func[PMBUS_PAGES];	/* Functionality, per page */
+	/*
+	 * The get_status function maps manufacturing specific status values
+	 * into PMBus standard status values.
+	 * This function is optional and only necessary if chip specific status
+	 * register values have to be mapped into standard PMBus status register
+	 * values.
+	 */
+	int (*get_status)(struct i2c_client *client, int page, int reg);
+	/*
+	 * The identify function determines supported PMBus functionality.
+	 * This function is only necessary if a chip driver supports multiple
+	 * chips, and the chip functionality is not pre-determined.
+	 */
+	int (*identify)(struct i2c_client *client,
+			struct pmbus_driver_info *info);
+};
+
+/* Function declarations */
+
+int pmbus_set_page(struct i2c_client *client, u8 page);
+int pmbus_read_word_data(struct i2c_client *client, u8 page, u8 reg);
+void pmbus_clear_faults(struct i2c_client *client);
+bool pmbus_check_byte_register(struct i2c_client *client, int page, int reg);
+bool pmbus_check_word_register(struct i2c_client *client, int page, int reg);
+int pmbus_do_probe(struct i2c_client *client, const struct i2c_device_id *id,
+		   struct pmbus_driver_info *info);
+int pmbus_do_remove(struct i2c_client *client);
+const struct pmbus_driver_info *pmbus_get_driver_info(struct i2c_client
+						      *client);
+
+#endif /* PMBUS_H */

include/linux/i2c/pmbus.h

+/*
+ * Hardware monitoring driver for PMBus devices
+ *
+ * Copyright (c) 2010, 2011 Ericsson AB.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef _PMBUS_H_
+#define _PMBUS_H_
+
+/* flags */
+
+/*
+ * PMBUS_SKIP_STATUS_CHECK
+ *
+ * During register detection, skip checking the status register for
+ * communication or command errors.
+ *
+ * Some PMBus chips respond with valid data when trying to read an unsupported
+ * register. For such chips, checking the status register is mandatory when
+ * trying to determine if a chip register exists or not.
+ * Other PMBus chips don't support the STATUS_CML register, or report
+ * communication errors for no explicable reason. For such chips, checking
+ * the status register must be disabled.
+ */
+#define PMBUS_SKIP_STATUS_CHECK	(1 << 0)
+
+struct pmbus_platform_data {
+	u32 flags;		/* Device specific flags */
+};
+
+#endif /* _PMBUS_H_ */