hwmon: PMBus device driver

This driver adds support for hardware monitoring features of various PMBus
devices.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Acked-by: Jonathan 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

@@ -0,0 +1,203 @@
+/*
+ * 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);