Message-ID: <20100414161904.713eef78@lxorguk.ukuu.org.uk>
Date:	Wed, 14 Apr 2010 16:19:04 +0100
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Jonathan Cameron <kernel@...23.retrosnub.co.uk>
Cc:	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] hmc6352: Add driver for the HMC6352 compass

Ripping it out of hwmon and applying the hedge trimmers to everything not
needed and we get this for drivers/misc. I've also swapped the command
codes to characters as the datasheet specifies them in ascii.

--------------------------------8<------------------------------

hmc6352: Add driver for the HMC6352 compass

From: Kalhan Trisal <kalhan.trisal@...el.com>

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

(Some cleanups from Alan Cox)

Signed-off-by: Kalhan Trisal <kalhan.trisal@...el.com>
Signed-off-by: Alan Cox <alan@...ux.intel.com>
---

 drivers/misc/Kconfig   |    7 ++
 drivers/misc/Makefile  |    1 
 drivers/misc/hmc6352.c |  199 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 207 insertions(+), 0 deletions(-)
 create mode 100644 drivers/misc/hmc6352.c


diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 2191c8d..e626bac 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -278,6 +278,13 @@ config SENSORS_TSL2550
 	  This driver can also be built as a module.  If so, the module
 	  will be called tsl2550.
 
+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 208ae30..620cf0b 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -26,5 +26,6 @@ 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/
diff --git a/drivers/misc/hmc6352.c b/drivers/misc/hmc6352.c
new file mode 100644
index 0000000..f4162ea
--- /dev/null
+++ b/drivers/misc/hmc6352.c
@@ -0,0 +1,199 @@
+/*
+ * 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 ssize_t compass_calibration_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	int ret;
+	unsigned long val;
+	char  cmd = 'C';	/* Calibrate */
+	char  cmd1 = 'E';	/* Exit calibration mode */
+	struct i2c_msg msg[] = {
+		{ client->addr, 0, 1, &cmd },
+	};
+	struct i2c_msg msg1[] = {
+		{ client->addr, 0, 1, &cmd1 },
+	};
+
+	if (strict_strtoul(buf, 10, &val))
+		return -EINVAL;
+	if (val == 1) {
+		ret = i2c_transfer(client->adapter, msg, 1);
+		if (ret != 1) {
+			dev_warn(dev, "hmc6352_comp: i2c calib start cmd failed\n");
+			return ret;
+		}
+	} else if (val == 2) {
+		ret = i2c_transfer(client->adapter, msg1, 1);
+		if (ret != 1) {
+			dev_warn(dev, "hmc6352_comp: i2c calib stop cmd failed\n");
+			return ret;
+		}
+	} else
+		return -EINVAL;
+
+	return count;
+}
+
+static ssize_t compass_heading_data_show(struct device *dev,
+			struct device_attribute *attr, char *buf)
+{
+
+	struct i2c_client *client = to_i2c_client(dev);
+	static char cmd = 'A';		/* Get Data */
+	unsigned char i2c_data[2];
+	unsigned int ret, ret_val;
+	struct i2c_msg msg[] = {
+		{ client->addr, 0, 1, &cmd },
+	};
+	struct i2c_msg msg1[] = {
+		{ client->addr, I2C_M_RD, 2, i2c_data },
+	};
+
+	ret = i2c_transfer(client->adapter, msg, 1);
+	if (ret != 1) {
+		dev_warn(dev, "hmc6352: i2c cmd 0x41 failed\n");
+		return ret;
+	}
+	msleep(10); /* sending 0x41 cmd we need to wait for 7-10 milli second*/
+	ret = i2c_transfer(client->adapter, msg1, 1);
+	if (ret != 1) {
+		dev_warn(dev, "hmc6352: i2c read data cmd failed\n");
+		return ret;
+	}
+	ret_val = i2c_data[0];
+	ret_val = ((ret_val << 8) | i2c_data[1]);
+	return sprintf(buf, "%d.%d\n", ret_val/10, ret_val%10);
+}
+
+static ssize_t compass_power_mode_store(struct device *dev,
+		struct device_attribute *attr, const  char *buf, size_t count)
+{
+
+	struct i2c_client *client = to_i2c_client(dev);
+	unsigned long val;
+	unsigned int ret;
+	static char cmd = 'S';		/* Sleep mode */
+	static char cmd1 = 'W';		/* Wake up */
+	struct i2c_msg msg[] = {
+		{ client->addr, 0, 1, &cmd },
+	};
+	struct i2c_msg msg1[] = {
+		{ client->addr, 0, 1, &cmd1 },
+	};
+
+	if (strict_strtoul(buf, 10, &val))
+		return -EINVAL;
+
+	if (val == 0) {
+		ret = i2c_transfer(client->adapter, msg, 1);
+		if (ret != 1)
+			dev_warn(dev, "hmc6352: i2c cmd  sleep mode failed\n");
+	} else if (val == 1) {
+		ret = i2c_transfer(client->adapter, msg1, 1);
+		if (ret != 1)
+			dev_warn(dev, "hmc6352: i2c cmd active mode failed\n");
+	} else
+		return -EINVAL;
+
+	return count;
+}
+
+static DEVICE_ATTR(heading, 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_heading.attr,
+	&dev_attr_calibration.attr,
+	&dev_attr_power_state.attr,
+	NULL
+};
+
+static 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, "hmc6352: 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@...el.com");
+MODULE_DESCRIPTION("hmc6352 Compass Driver");
+MODULE_LICENSE("GPL v2");
--
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