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>

1 files changed, 203 insertions, 0 deletions

diff --git a/drivers/hwmon/pmbus.c b/drivers/hwmon/pmbus.c
new file mode 100644
index 000000000000..98e2e28899e2
--- /dev/null
+++ b/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);