From: Steven King <sfking@fdwdc.com>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Subject: [PATCH][input] add Honeywell hmc5843 3-Axis Magnetometer (digital compass)  driver.
Date: Thu, 10 Dec 2009 22:50:12 -0800
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Signed-off-by: Steven King <sfking@fdwdc.com>

---

 drivers/input/misc/Kconfig   |   10 +
 drivers/input/misc/Makefile  |    1 +
 drivers/input/misc/hmc5843.c |  515 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 526 insertions(+), 0 deletions(-)
 create mode 100644 drivers/input/misc/hmc5843.c

diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index a9bb254..7564b96 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -317,4 +317,14 @@ config INPUT_PCAP
 	  To compile this driver as a module, choose M here: the
 	  module will be called pcap_keys.
 
+config INPUT_HMC5843
+	tristate "Honeywell HMC5843 3-Axis Magnetometer"
+	depends on I2C && SYSFS
+	select INPUT_POLLDEV
+	help
+	  Say Y here to add support for the Honeywell HMC 5843 3-Axis
+	  Magnetometer (digital compass).
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called hmc5843.
 endif
diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
index a8b8485..825b70c 100644
--- a/drivers/input/misc/Makefile
+++ b/drivers/input/misc/Makefile
@@ -30,4 +30,5 @@ obj-$(CONFIG_INPUT_WINBOND_CIR)		+= winbond-cir.o
 obj-$(CONFIG_INPUT_WISTRON_BTNS)	+= wistron_btns.o
 obj-$(CONFIG_INPUT_WM831X_ON)		+= wm831x-on.o
 obj-$(CONFIG_INPUT_YEALINK)		+= yealink.o
+obj-$(CONFIG_INPUT_HMC5843)		+= hmc5843.o
 
diff --git a/drivers/input/misc/hmc5843.c b/drivers/input/misc/hmc5843.c
new file mode 100644
index 0000000..51bb86c
--- /dev/null
+++ b/drivers/input/misc/hmc5843.c
@@ -0,0 +1,515 @@
+/*
+ * Driver for the Honeywell HMC5843 3-Axis Magnetometer.
+ *
+ * Author: Steven King <sfking@fdwdc.com>
+ *
+ * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/jiffies.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/input-polldev.h>
+
+#define	HMC5843_CFG_A_REG			0
+#define		HMC5843_CFG_A_BIAS_MASK		0x03
+#define		HMC5843_CFG_A_RATE_MASK		0x1c
+#define		HMC5843_CFG_A_RATE_SHIFT	2
+#define	HMC5843_CFG_B_REG			1
+#define		MMC5843_CFG_B_GAIN_MASK		0xe0
+#define		MMC5843_CFG_B_GAIN_SHIFT	5
+#define	HMC5843_MODE_REG			2
+#define		HMC5843_MODE_REPEAT		0
+#define		HMC5843_MODE_ONCE		1
+#define		HMC5843_MODE_IDLE		2
+#define		HMC5843_MODE_SLEEP		3
+#define	HMC5843_X_DATA_REG			3
+#define	HMC5843_Y_DATA_REG			5
+#define	HMC5843_Z_DATA_REG			7
+#define	HMC5843_STATUS_REG			9
+#define		HMC5843_STATUS_REN		0x04
+#define		HMC5843_STATUS_LOCK		0x02
+#define		HMC5843_STATUS_RDY		0x01
+#define	HMC5843_ID_REG_A			10
+#define	HMC5843_ID_REG_B			11
+#define	HMC5843_ID_REG_C			12
+#define	HMC5843_LAST_REG			12
+#define	HMC5843_NUM_REG				13
+
+struct hmc5843 {
+	struct i2c_client	*client;
+	struct mutex		lock;
+	struct input_polled_dev	*ipdev;
+	int			bias;
+	int			gain;
+	int			rate;
+	int			mode;
+	int			index;
+};
+
+/* interval between samples for the different rates, in msecs */
+static const unsigned int hmc5843_sample_interval[] = {
+	1000 * 2,	1000,		1000 / 2,	1000 / 5,
+	1000 / 10,	1000 / 20,	1000 / 50,
+};
+
+/*
+ * From the datasheet:
+ *
+ * The devices uses an address pointer to indicate which register location is
+ * to be read from or written to. These pointer locations are sent from the
+ * master to this slave device and succeed the 7-bit address plus 1 bit
+ * read/write identifier.
+ *
+ * To minimize the communication between the master and this device, the
+ * address pointer updated automatically without master intervention. This
+ * automatic address pointer update has two additional features. First when
+ * address 12 or higher is accessed the pointer updates to address 00 and
+ * secondly when address 09 is reached, the pointer rolls back to address 03.
+ * Logically, the address pointer operation functions as shown below.
+ *
+ * If (address pointer = 09) then address pointer = 03
+ * Else if (address pointer >= 12) then address pointer = 0
+ * Else (address pointer) = (address pointer) + 1
+ *
+ * Since the set of operations performed by this driver is pretty simple,
+ * we keep track of the register being written to when updating the
+ * configuration and when reading data only update the address ptr when its not
+ * pointing to the first data register.
+*/
+
+static int hmc5843_write_register(struct hmc5843 *hmc5843, int index)
+{
+	u8 buf[2];
+	int result;
+
+	buf[0] = index;
+	if (index == HMC5843_CFG_A_REG)
+		buf[1] = hmc5843->bias |
+			(hmc5843->rate << HMC5843_CFG_A_RATE_SHIFT);
+	else if (index == HMC5843_CFG_B_REG)
+		buf[1] = hmc5843->gain << MMC5843_CFG_B_GAIN_SHIFT;
+	else if (index == HMC5843_MODE_REG)
+		buf[1] = hmc5843->mode;
+	else
+		return -EINVAL;
+	result = i2c_master_send(hmc5843->client, buf, sizeof(buf));
+
+	if (result != 2) {
+		hmc5843->index = -1;
+		return result;
+	}
+	hmc5843->index = index + 1;
+	return 0;
+}
+
+static int hmc5843_read_xyz(struct hmc5843 *hmc5843, int *x, int *y, int *z)
+{
+	struct i2c_msg msgs[2];
+	u8 buf[6];
+	int n = 0;
+	int result;
+
+	if (hmc5843->index != HMC5843_X_DATA_REG) {
+		buf[0]		= HMC5843_X_DATA_REG;
+
+		msgs[0].addr	= hmc5843->client->addr;
+		msgs[0].flags	= 0;
+		msgs[0].buf	= buf;
+		msgs[0].len	= 1;
+
+		hmc5843->index	= HMC5843_X_DATA_REG;
+		n = 1;
+	}
+	msgs[n].addr	= hmc5843->client->addr;
+	msgs[n].flags	= I2C_M_RD;
+	msgs[n].buf	= buf;
+	msgs[n].len	= 6;
+	++n;
+
+	result = i2c_transfer(hmc5843->client->adapter, msgs, n);
+	if (result != n) {
+		hmc5843->index = -1;
+		return result;
+	}
+
+	*x = (((int)((s8)buf[0])) << 8) | buf[1];
+	*y = (((int)((s8)buf[2])) << 8) | buf[3];
+	*z = (((int)((s8)buf[4])) << 8) | buf[5];
+	return 0;
+}
+
+/* sysfs stuff */
+
+/* bias */
+static ssize_t hmc5843_show_bias(struct device *dev,
+				 struct device_attribute *attr,
+				 char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct hmc5843 *hmc5843 = i2c_get_clientdata(client);
+
+	return sprintf(buf, "%d\n", hmc5843->bias);
+}
+
+static ssize_t hmc5843_store_bias(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct hmc5843 *hmc5843 = i2c_get_clientdata(client);
+	unsigned long val;
+	int status = count;
+
+	if ((strict_strtol(buf, 10, &val) < 0) || (val > 2))
+		return -EINVAL;
+	mutex_lock(&hmc5843->lock);
+	if (hmc5843->bias != val) {
+		hmc5843->bias = val;
+		status = hmc5843_write_register(hmc5843, HMC5843_CFG_A_REG);
+	}
+	mutex_unlock(&hmc5843->lock);
+	return status;
+}
+
+static DEVICE_ATTR(bias, S_IWUSR | S_IRUGO, hmc5843_show_bias,
+		hmc5843_store_bias);
+
+/* rate */
+static ssize_t hmc5843_show_rate(struct device *dev,
+				 struct device_attribute *attr,
+				 char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct hmc5843 *hmc5843 = i2c_get_clientdata(client);
+
+	return sprintf(buf, "%d\n", hmc5843->rate);
+}
+
+static ssize_t hmc5843_store_rate(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct hmc5843 *hmc5843 = i2c_get_clientdata(client);
+	unsigned long val;
+	int status = count;
+
+	if ((strict_strtol(buf, 10, &val) < 0) || (val > 6))
+		return -EINVAL;
+	mutex_lock(&hmc5843->lock);
+	if (hmc5843->rate != val) {
+		hmc5843->rate = val;
+		hmc5843->ipdev->poll_interval = hmc5843_sample_interval[val];
+		status = hmc5843_write_register(hmc5843, HMC5843_CFG_A_REG);
+	}
+	mutex_unlock(&hmc5843->lock);
+	return status;
+}
+
+static DEVICE_ATTR(rate, S_IWUSR | S_IRUGO, hmc5843_show_rate,
+		hmc5843_store_rate);
+
+/* gain */
+static ssize_t hmc5843_show_gain(struct device *dev,
+				 struct device_attribute *attr,
+				 char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct hmc5843 *hmc5843 = i2c_get_clientdata(client);
+
+	return sprintf(buf, "%d\n", hmc5843->gain);
+}
+
+static ssize_t hmc5843_store_gain(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct hmc5843 *hmc5843 = i2c_get_clientdata(client);
+	unsigned long val;
+	int status = count;
+
+	if ((strict_strtol(buf, 10, &val) < 0) || (val > 6))
+		return -EINVAL;
+	mutex_lock(&hmc5843->lock);
+	if (hmc5843->gain != val) {
+		hmc5843->gain = val;
+		status = hmc5843_write_register(hmc5843, HMC5843_CFG_B_REG);
+	}
+	mutex_unlock(&hmc5843->lock);
+	return status;
+}
+
+static DEVICE_ATTR(gain, S_IWUSR | S_IRUGO, hmc5843_show_gain,
+		hmc5843_store_gain);
+
+/* mode */
+static ssize_t hmc5843_show_mode(struct device *dev,
+				 struct device_attribute *attr,
+				 char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct hmc5843 *hmc5843 = i2c_get_clientdata(client);
+
+	return sprintf(buf, "%d\n", hmc5843->mode);
+}
+
+static ssize_t hmc5843_store_mode(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct hmc5843 *hmc5843 = i2c_get_clientdata(client);
+	unsigned long val;
+	int status = count;
+
+	if ((strict_strtol(buf, 10, &val) < 0) || (val > 3))
+		return -EINVAL;
+	mutex_lock(&hmc5843->lock);
+	if (hmc5843->mode != val) {
+		hmc5843->mode = val;
+		status = hmc5843_write_register(hmc5843, HMC5843_MODE_REG);
+	}
+	mutex_unlock(&hmc5843->lock);
+	return status;
+}
+
+static DEVICE_ATTR(mode, S_IWUSR | S_IRUGO, hmc5843_show_mode,
+		hmc5843_store_mode);
+
+static struct attribute *hmc5843_attributes[] = {
+	&dev_attr_bias.attr,
+	&dev_attr_rate.attr,
+	&dev_attr_gain.attr,
+	&dev_attr_mode.attr,
+	NULL,
+};
+
+static const struct attribute_group hmc5843_attr_group = {
+	.attrs = hmc5843_attributes,
+};
+
+/* use polled input device */
+
+static void hmc5843_poll(struct input_polled_dev *ipdev)
+{
+	struct hmc5843 *hmc5843 = ipdev->private;
+	int x, y, z;
+
+	mutex_lock(&hmc5843->lock);
+	if (!hmc5843_read_xyz(hmc5843, &x, &y, &z)) {
+		input_report_abs(ipdev->input, ABS_X, x);
+		input_report_abs(ipdev->input, ABS_Y, y);
+		input_report_abs(ipdev->input, ABS_Z, z);
+		input_sync(ipdev->input);
+	}
+	mutex_unlock(&hmc5843->lock);
+}
+
+static int __devinit hmc5843_input_init(struct hmc5843 *hmc5843)
+{
+	int status;
+	struct input_polled_dev *ipdev;
+
+	ipdev = input_allocate_polled_device();
+	if (!ipdev) {
+		dev_dbg(&hmc5843->client->dev, "error creating input device\n");
+		return -ENOMEM;
+	}
+	ipdev->poll = hmc5843_poll;
+	ipdev->poll_interval = hmc5843_sample_interval[hmc5843->rate];
+	ipdev->private = hmc5843;
+
+	ipdev->input->name = "Honeywell HMC5843 3-Axis Magnetometer";
+	ipdev->input->phys = "hmc5843/input0";
+	ipdev->input->id.bustype = BUS_HOST;
+
+	set_bit(EV_ABS, ipdev->input->evbit);
+
+	input_set_abs_params(ipdev->input, ABS_X, -2047, 2047, 0, 0);
+	input_set_abs_params(ipdev->input, ABS_Y, -2047, 2047, 0, 0);
+	input_set_abs_params(ipdev->input, ABS_Z, -2047, 2047, 0, 0);
+
+	status = input_register_polled_device(ipdev);
+	if (status) {
+		dev_dbg(&hmc5843->client->dev,
+				"error registering input device\n");
+		input_free_polled_device(ipdev);
+		goto exit;
+	}
+	hmc5843->ipdev = ipdev;
+exit:
+	return status;
+}
+
+static int __devinit hmc5843_device_init(struct hmc5843 *hmc5843)
+{
+	struct i2c_client *client = hmc5843->client;
+	int status;
+
+	struct i2c_msg msgs[2];
+	u8 buf[6] = { HMC5843_ID_REG_A }; /* start reading at 1st id reg */
+
+	msgs[0].addr = client->addr;
+	msgs[0].flags = 0;
+	msgs[0].buf = buf;
+	msgs[0].len = 1;
+	msgs[1].addr = client->addr;
+	msgs[1].flags = I2C_M_RD;
+	msgs[1].buf = buf; /* overwrite sent address on read */
+	msgs[1].len = 6; /* 3 id regs + cfg_a, cfg_b & mode reg */
+
+	status = i2c_transfer(client->adapter, msgs, 2);
+	if (status != 2) {
+		dev_dbg(&client->dev, "unable to contact device\n");
+		return status;
+	}
+	if (strncmp(buf, "H43", 3)) {
+		dev_dbg(&client->dev, "incorrect device id %-3.3s", buf);
+		return -EINVAL;
+	}
+	/* the read will have wrapped to 0, bytes 3-6 are cfg_a, cfg_b, mode */
+	hmc5843->bias = buf[3] & HMC5843_CFG_A_BIAS_MASK;
+	hmc5843->rate = buf[3] >> HMC5843_CFG_A_RATE_SHIFT;
+	hmc5843->gain = buf[4] >> MMC5843_CFG_B_GAIN_SHIFT;
+	hmc5843->mode = buf[5];
+
+	hmc5843->index = 3;
+	mutex_init(&hmc5843->lock);
+	return 0;
+}
+
+static int __devinit hmc5843_i2c_probe(struct i2c_client *client,
+					const struct i2c_device_id *id)
+{
+	int status;
+	struct hmc5843 *hmc5843;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+		dev_dbg(&client->dev, "adapter doesn't support I2C\n");
+		return -ENODEV;
+	}
+
+	hmc5843 = kzalloc(sizeof(*hmc5843), GFP_KERNEL);
+	if (!hmc5843) {
+		dev_dbg(&client->dev, "unable to allocate memory\n");
+		return -ENOMEM;
+	}
+
+	hmc5843->client = client;
+	i2c_set_clientdata(client, hmc5843);
+
+	status = hmc5843_device_init(hmc5843);
+	if (status)
+		goto fail0;
+
+	status = hmc5843_input_init(hmc5843);
+	if (status)
+		goto fail0;
+
+	status = sysfs_create_group(&client->dev.kobj, &hmc5843_attr_group);
+	if (status) {
+		dev_dbg(&client->dev, "could not create sysfs files\n");
+		goto fail1;
+	}
+	return 0;
+fail1:
+	input_unregister_polled_device(hmc5843->ipdev);
+fail0:
+	kfree(hmc5843);
+	return status;
+}
+
+static int __devexit hmc5843_i2c_remove(struct i2c_client *client)
+{
+	struct hmc5843 *hmc5843 = i2c_get_clientdata(client);
+
+	sysfs_remove_group(&client->dev.kobj, &hmc5843_attr_group);
+	input_unregister_polled_device(hmc5843->ipdev);
+	i2c_set_clientdata(client, NULL);
+	kfree(hmc5843);
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int hmc5843_suspend(struct device *dev)
+{
+	struct i2c_client *client = dev_get_drvdata(dev);
+	struct hmc5843 *hmc5843 = i2c_get_clientdata(client);
+
+	/* save our current mode for resume and put device to sleep */
+	int m = hmc5843->mode;
+	hmc5843->mode = HMC5843_MODE_SLEEP;
+	hmc5843_write_register(hmc5843, HMC5843_MODE_REG);
+	hmc5843->mode = m;
+	return 0;
+}
+
+static int hmc5843_resume(struct device *dev)
+{
+	struct i2c_client *client = dev_get_drvdata(dev);
+	struct hmc5843 *hmc5843 = i2c_get_clientdata(client);
+
+	/* restore whatever mode we were in before suspending */
+	hmc5843_write_register(hmc5843, HMC5843_MODE_REG);
+	return 0;
+}
+
+static struct dev_pm_ops hmc5843_dev_pm_ops = {
+	.suspend	= hmc5843_suspend,
+	.resume		= hmc5843_resume,
+};
+
+#define HMC5843_DEV_PM_OPS (&hmc5843_dev_pm_ops)
+#else
+#define	HMC5843_DEV_PM_OPS NULL
+#endif
+
+static const struct i2c_device_id hmc5843_id[] = {
+	{ "hmc5843", 0 },
+	{ },
+};
+
+MODULE_DEVICE_TABLE(i2c, hmc5843_id);
+
+static struct i2c_driver hmc5843_i2c_driver = {
+	.driver		= {
+		.name	= "hmc5843",
+		.owner	= THIS_MODULE,
+		.pm	= HMC5843_DEV_PM_OPS,
+	},
+	.probe		= hmc5843_i2c_probe,
+	.remove		= __devexit_p(hmc5843_i2c_remove),
+	.id_table	= hmc5843_id,
+};
+
+static int __init hmc5843_init(void)
+{
+	return i2c_add_driver(&hmc5843_i2c_driver);
+}
+module_init(hmc5843_init);
+
+static void __exit hmc5843_exit(void)
+{
+	i2c_del_driver(&hmc5843_i2c_driver);
+}
+module_exit(hmc5843_exit);
+
+MODULE_AUTHOR("Steven King <sfking@fdwdc.com>");
+MODULE_DESCRIPTION("Honeywell HMC5843 3-Axis Magnetometer driver");
+MODULE_LICENSE("GPL");
--
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