hmc6352: add driver for the HMC6352 compass

This driver will report the heading values in degrees to the sysfs
interface.  The values returned are headings .  e.g.  245.6

Alan: Cleanups requested now all folded in and a sysfs description to keep
Andrew happy. The sysfs description now resembles hwmon.

Signed-off-by: Kalhan Trisal <kalhan.trisal@intel.com>
Reviewed-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 195 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-i2c-devices-hm6352 b/Documentation/ABI/testing/sysfs-bus-i2c-devices-hm6352
new file mode 100644
index 000000000000..feb2e4a87075
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-i2c-devices-hm6352
@@ -0,0 +1,21 @@
+Where:          /sys/bus/i2c/devices/.../heading0_input
+Date:           April 2010
+Kernel Version: 2.6.36?
+Contact:        alan.cox@intel.com
+Description:    Reports the current heading from the compass as a floating
+                point value in degrees.
+
+Where:          /sys/bus/i2c/devices/.../power_state
+Date:           April 2010
+Kernel Version: 2.6.36?
+Contact:        alan.cox@intel.com
+Description:    Sets the power state of the device. 0 sets the device into
+                sleep mode, 1 wakes it up.
+
+Where:          /sys/bus/i2c/devices/.../calibration
+Date:           April 2010
+Kernel Version: 2.6.36?
+Contact:        alan.cox@intel.com
+Description:    Sets the calibration on or off (1 = on, 0 = off). See the
+                chip data sheet.
+
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 3b4b7562b2fa..0b591b658243 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -314,6 +314,13 @@ config SENSORS_BH1780
           This driver can also be built as a module.  If so, the module
           will be called bh1780gli.
 
+config HMC6352
+        tristate "Honeywell HMC6352 compass"
+        depends on I2C
+        help
+          This driver provides support for the Honeywell HMC6352 compass,
+          providing configuration and heading data via sysfs.
+
 config EP93XX_PWM
         tristate "EP93xx PWM support"
         depends on ARCH_EP93XX
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index c0621fbacb27..255a80dc9d73 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -30,6 +30,7 @@ obj-$(CONFIG_DS1682)		+= ds1682.o
 obj-$(CONFIG_TI_DAC7512)        += ti_dac7512.o
 obj-$(CONFIG_C2PORT)            += c2port/
 obj-$(CONFIG_IWMC3200TOP)      += iwmc3200top/
+obj-$(CONFIG_HMC6352)           += hmc6352.o
 obj-y                           += eeprom/
 obj-y                           += cb710/
 obj-$(CONFIG_VMWARE_BALLOON)    += vmware_balloon.o
diff --git a/drivers/misc/hmc6352.c b/drivers/misc/hmc6352.c
new file mode 100644
index 000000000000..234bfcaf2099
--- /dev/null
+++ b/drivers/misc/hmc6352.c
@@ -0,0 +1,166 @@
+/*
+ * hmc6352.c - Honeywell Compass Driver
+ *
+ * Copyright (C) 2009 Intel Corp
+ *
+ *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * 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; version 2 of the License.
+ *
+ * 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.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/err.h>
+#include <linux/delay.h>
+#include <linux/sysfs.h>
+
+static DEFINE_MUTEX(compass_mutex);
+
+static int compass_command(struct i2c_client *c, u8 cmd)
+{
+        int ret = i2c_master_send(c, &cmd, 1);
+        if (ret < 0)
+                dev_warn(&c->dev, "command '%c' failed.\n", cmd);
+        return ret;
+}
+
+static int compass_store(struct device *dev, const char *buf, size_t count,
+                        const char *map)
+{
+        struct i2c_client *c = to_i2c_client(dev);
+        int ret;
+        unsigned long val;
+
+        if (strict_strtoul(buf, 10, &val))
+                return -EINVAL;
+        if (val >= strlen(map))
+                return -EINVAL;
+        mutex_lock(&compass_mutex);
+        ret = compass_command(c, map[val]);
+        mutex_unlock(&compass_mutex);
+        if (ret < 0)
+                return ret;
+        return count;
+}
+
+static ssize_t compass_calibration_store(struct device *dev,
+                struct device_attribute *attr, const char *buf, size_t count)
+{
+        return compass_store(dev, buf, count, "EC");
+}
+
+static ssize_t compass_power_mode_store(struct device *dev,
+                struct device_attribute *attr, const  char *buf, size_t count)
+{
+        return compass_store(dev, buf, count, "SW");
+}
+
+static ssize_t compass_heading_data_show(struct device *dev,
+                        struct device_attribute *attr, char *buf)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+        unsigned char i2c_data[2];
+        unsigned int ret;
+
+        mutex_lock(&compass_mutex);
+        ret = compass_command(client, 'A');
+        if (ret != 1) {
+                mutex_unlock(&compass_mutex);
+                return ret;
+        }
+        msleep(10); /* sending 'A' cmd we need to wait for 7-10 millisecs */
+        ret = i2c_master_recv(client, i2c_data, 2);
+        mutex_unlock(&compass_mutex);
+        if (ret != 1) {
+                dev_warn(dev, "i2c read data cmd failed\n");
+                return ret;
+        }
+        ret = (i2c_data[0] << 8) | i2c_data[1];
+        return sprintf(buf, "%d.%d\n", ret/10, ret%10);
+}
+
+
+static DEVICE_ATTR(heading0_input, S_IRUGO, compass_heading_data_show, NULL);
+static DEVICE_ATTR(calibration, S_IWUSR, NULL, compass_calibration_store);
+static DEVICE_ATTR(power_state, S_IWUSR, NULL, compass_power_mode_store);
+
+static struct attribute *mid_att_compass[] = {
+        &dev_attr_heading0_input.attr,
+        &dev_attr_calibration.attr,
+        &dev_attr_power_state.attr,
+        NULL
+};
+
+static const struct attribute_group m_compass_gr = {
+        .name = "hmc6352",
+        .attrs = mid_att_compass
+};
+
+static int hmc6352_probe(struct i2c_client *client,
+                                        const struct i2c_device_id *id)
+{
+        int res;
+
+        res = sysfs_create_group(&client->dev.kobj, &m_compass_gr);
+        if (res) {
+                dev_err(&client->dev, "device_create_file failed\n");
+                return res;
+        }
+        dev_info(&client->dev, "%s HMC6352 compass chip found\n",
+                                                        client->name);
+        return 0;
+}
+
+static int hmc6352_remove(struct i2c_client *client)
+{
+        sysfs_remove_group(&client->dev.kobj, &m_compass_gr);
+        return 0;
+}
+
+static struct i2c_device_id hmc6352_id[] = {
+        { "hmc6352", 0 },
+        { }
+};
+
+MODULE_DEVICE_TABLE(i2c, hmc6352_id);
+
+static struct i2c_driver hmc6352_driver = {
+        .driver = {
+                .name = "hmc6352",
+        },
+        .probe = hmc6352_probe,
+        .remove = hmc6352_remove,
+        .id_table = hmc6352_id,
+};
+
+static int __init sensor_hmc6352_init(void)
+{
+        return i2c_add_driver(&hmc6352_driver);
+}
+
+static void  __exit sensor_hmc6352_exit(void)
+{
+        i2c_del_driver(&hmc6352_driver);
+}
+
+module_init(sensor_hmc6352_init);
+module_exit(sensor_hmc6352_exit);
+
+MODULE_AUTHOR("Kalhan Trisal <kalhan.trisal@intel.com");
+MODULE_DESCRIPTION("hmc6352 Compass Driver");
+MODULE_LICENSE("GPL v2");