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Message-ID: <4C1A12C6.6070704@cam.ac.uk>
Date: Thu, 17 Jun 2010 13:19:18 +0100
From: Jonathan Cameron <jic23@....ac.uk>
To: Alan Cox <alan@...rguk.ukuu.org.uk>
CC: Jean Delvare <khali@...ux-fr.org>, linux-i2c@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hmc6352: Add driver for the HMC6352 compass
On 06/17/10 12:50, Alan Cox wrote:
>>> + struct i2c_msg msg1[] = {
>>> + { client->addr, 0, 1, &cmd1 },
>>> + };
>>
>> It's quite overkill IMHO to have two messages here. In the end you send
>> only one. It would make sense if you made these messages static const,
>
> They can't be const but I cleaned it up based on your other suggestions and
> then jumped up and down on it a bit more.
>
>
> 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
>
> Cleanups requested now all folded in and a sysfs description to keep Andrew
> happy.
>
> Signed-off-by: Kalhan Trisal <kalhan.trisal@...el.com>
> Signed-off-by: Alan Cox <alan@...ux.intel.com>
Hi Alan,
I guess it is pretty unlikely anyone would ever have more than one compass and
if they do they can deal with the mutex sharing if they care.
I think there is a small issue where the code and documentation don't match
for the calibration attribute. The version in the docs makes more sense to
me and I think it will slightly simplify the code.
Fix that and I'm happy to add:
Acked-by: Jonathan Cameron <jic23@....ac.uk>
> ---
>
> .../ABI/testing/sysfs-bus-i2c-devices-hm6352 | 21 +++
> drivers/misc/Kconfig | 7 +
> drivers/misc/Makefile | 1
> drivers/misc/hmc6352.c | 165 ++++++++++++++++++++
> 4 files changed, 194 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..feb2e4a
> --- /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@...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.
I think there is a disrepancy between what is described here and what the code
does. Looks to me like values are 1 for on and 2 for off in the code (which
is a little odd).
> +
> 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..3243c8c
> --- /dev/null
> +++ b/drivers/misc/hmc6352.c
> @@ -0,0 +1,165 @@
> +/*
> + * 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 < 0 || val >= strlen(map) || map[val] == ' ')
> + return -EINVAL;
> + mutex_lock(&compass_mutex);
> + ret = compass_command(c, map[val]);
> + mutex_unlock(&compass_mutex);
> + return ret;
> +}
> +
> +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, " CE");
> +}
> +
> +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);
> +}
> +
If we are being ludicrously fussy, no point in 2 blank lines here...
> +
> +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@...el.com");
> +MODULE_DESCRIPTION("hmc6352 Compass Driver");
> +MODULE_LICENSE("GPL v2");
>
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