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Message-ID: <4C18E3B8.7020308@cam.ac.uk>
Date: Wed, 16 Jun 2010 15:46:16 +0100
From: Jonathan Cameron <jic23@....ac.uk>
To: Alan Cox <alan@...ux.intel.com>
CC: linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hmc6352: Add driver for the HMC6352 compass
On 06/16/10 13:16, Alan Cox wrote:
> 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
>
> Cleanups requested now all folded in and a sysfs descriptio to keep Andrew
> happy.
Hi Alan,
Others seem to have reviewed the code fairly thoroughly so the only question I want
to raise is that of the attribute naming. As the only other magnetometer in tree afaik
(adis16400 has one amongst numerous other things) doesn't actually overlap with
any of your attributes things are pretty unconstrained. Still as people have suggested
(and we have acted on wrt to IIO) I would advocate matching hwmon's naming structure where
it doesn't carry a significant cost. Simple arguement being that it is the biggest
sensor related subsystem and what it uses works.
So here we would have heading0_input.
As this only applies to the one attribute anyway and maintaining that if we
ever sweep all these drivers up into a common system would be trivial, this doesn't
really matter that much. Still if it doesn't cost anything....
(though obviously it does if you have userspace code in place!)
Thanks,
Jonathan
> Signed-off-by: Kalhan Trisal <kalhan.trisal@...el.com>
> Signed-off-by: Alan Cox <alan@...ux.intel.com>
> ---
>
> .../ABI/testing/sysfs-bus-i2c-devices-hm6352 | 21 ++
> drivers/misc/Kconfig | 7 +
> drivers/misc/Makefile | 1
> drivers/misc/hmc6352.c | 199 ++++++++++++++++++++
> 4 files changed, 228 insertions(+), 0 deletions(-)
> create mode 100644 Documentation/ABI/testing/sysfs-bus-i2c-devices-hm6352
> create mode 100644 drivers/misc/hmc6352.c
>
>
> 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 0000000..fbedf77
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-bus-i2c-devices-hm6352
> @@ -0,0 +1,21 @@
> +Where: /sys/bus/i2c/devices/.../heading
> +Date: April 2010
> +Kernel Version: 2.6.36?
> +Contact: alan.cox@...el.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@...el.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@...el.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 26386a9..9e825cb 100644
> --- a/drivers/misc/Kconfig
> +++ b/drivers/misc/Kconfig
> @@ -304,6 +304,13 @@ 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 6ed06a1..48597df 100644
> --- a/drivers/misc/Makefile
> +++ b/drivers/misc/Makefile
> @@ -28,6 +28,7 @@ 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 0000000..a62a03b
> --- /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, "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, "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, "i2c cmd 0x41 failed\n");
> + return ret;
> + }
> + msleep(10); /* sending 0x41 cmd we need to wait for 7-10 milli seconds */
> + ret = i2c_transfer(client->adapter, msg1, 1);
> + if (ret != 1) {
> + dev_warn(dev, "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, "i2c cmd sleep mode failed\n");
> + } else if (val == 1) {
> + ret = i2c_transfer(client->adapter, msg1, 1);
> + if (ret != 1)
> + dev_warn(dev, "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, "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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