Re: [PATCH] I2C: TSL2550 support.

Trilok Soni
2007-06-19T11:28:58Z

Hi Rodolfo,

On 6/19/07, Rodolfo Giometti <giometti@enneenne.com> wrote:
> Add support for Taos TSL2550 ambient light sensors.
> (http://www.taosinc.com/product_detail.asp?cateid=4&proid=18).
>
> Signed-off-by: Rodolfo Giometti <giometti@linux.it>
> ---
> drivers/i2c/chips/Kconfig | 10 +
> drivers/i2c/chips/Makefile | 1 +
> drivers/i2c/chips/tsl2550.c | 427 +++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 438 insertions(+), 0 deletions(-)
> create mode 100644 drivers/i2c/chips/tsl2550.c
>
> diff --git a/drivers/i2c/chips/Kconfig b/drivers/i2c/chips/Kconfig
> index ea085a0..b59c013 100644
> --- a/drivers/i2c/chips/Kconfig
> +++ b/drivers/i2c/chips/Kconfig
> @@ -124,4 +124,14 @@ config SENSORS_MAX6875
> This driver can also be built as a module. If so, the module
> will be called max6875.
>
> +config SENSORS_TSL2550
> + tristate "Taos TSL2550 ambient light sensor"
> + depends on I2C && EXPERIMENTAL
> + help
> + If you say yes here you get support for the Taos TSL2550
> + ambient light sensor.
> +
> + This driver can also be built as a module. If so, the module
> + will be called tsl2550.
> +
> endmenu
> diff --git a/drivers/i2c/chips/Makefile b/drivers/i2c/chips/Makefile
> index 779868e..1ef6a04 100644
> --- a/drivers/i2c/chips/Makefile
> +++ b/drivers/i2c/chips/Makefile
> @@ -12,6 +12,7 @@ obj-$(CONFIG_SENSORS_PCF8574) += pcf8574.o
> obj-$(CONFIG_SENSORS_PCF8591) += pcf8591.o
> obj-$(CONFIG_ISP1301_OMAP) += isp1301_omap.o
> obj-$(CONFIG_TPS65010) += tps65010.o
> +obj-$(CONFIG_SENSORS_TSL2550) += tsl2550.o
>
> ifeq ($(CONFIG_I2C_DEBUG_CHIP),y)
> EXTRA_CFLAGS += -DDEBUG
> diff --git a/drivers/i2c/chips/tsl2550.c b/drivers/i2c/chips/tsl2550.c
> new file mode 100644
> index 0000000..fd7f87c
> --- /dev/null
> +++ b/drivers/i2c/chips/tsl2550.c
> @@ -0,0 +1,427 @@
> +/*
> + * tsl2550.c - Linux kernel modules for ambient light sensor
> + *
> + * Copyright (C) 2007 Rodolfo Giometti <giometti@linux.it>
> + * Copyright (C) 2007 Eurotech S.p.A. <info@eurotech.it>
> + *
> + * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/slab.h>
> +#include <linux/i2c.h>
> +#include <linux/mutex.h>
> +#include <linux/delay.h>
> +
> +#define TSL2550_DRV_NAME "tsl2550"
> +#define DRIVER_VERSION "1.1.0"
> +
> +/* --- Defines ------------------------------------------------------------- */
> +
> +#define TSL2550_POWER_DOWN 0x00
> +#define TSL2550_POWER_UP 0x03
> +#define TSL2550_STANDARD_RANGE 0x18
> +#define TSL2550_EXTENDED_RANGE 0x1d
> +#define TSL2550_READ_ADC0 0x43
> +#define TSL2550_READ_ADC1 0x83
> +
> +/* --- Structs ------------------------------------------------------------- */
> +
> +struct tsl2550_data {
> + struct i2c_client *client;
> + struct mutex update_lock;
> +
> + unsigned int power_state : 1;
> + unsigned int operating_mode : 1;
> +};
> +
> +/* --- Management functions ------------------------------------------------ */
> +
> +static int tsl2550_set_operating_mode(struct i2c_client *client, int mode)
> +{
> + struct tsl2550_data *data = i2c_get_clientdata(client);
> + int ret;
> +
> + mode = !!mode;
> + if (mode == data->operating_mode)
> + return 0;
> +
> + if (mode == 0)
> + ret = i2c_smbus_write_byte(client, TSL2550_STANDARD_RANGE);
> + else
> + ret = i2c_smbus_write_byte(client, TSL2550_EXTENDED_RANGE);
> +
> + data->operating_mode = mode;
> +
> + return ret;
> +}
> +
> +static int tsl2550_set_power_state(struct i2c_client *client, int state)
> +{
> + struct tsl2550_data *data = i2c_get_clientdata(client);
> + int ret;
> +
> + state = !!state;
> + if (state == data->power_state)
> + return 0;
> +
> + if (state == 0)
> + ret = i2c_smbus_write_byte(client, TSL2550_POWER_DOWN);
> + else {
> + ret = i2c_smbus_write_byte(client, TSL2550_POWER_UP);
> +
> + /* On power up we should reset operating mode also... */
> + tsl2550_set_operating_mode(client, data->operating_mode);
> + }
> +
> + data->power_state = state;
> +
> + return ret;
> +}
> +
> +static int tsl2550_get_adc_value(struct i2c_client *client, int channel)
> +{
> + u8 cmd = channel == 0 ? TSL2550_READ_ADC0 : TSL2550_READ_ADC1;
> + unsigned long end;
> + int loop = 0, ret = 0;
> +
> + /* Read ADC channel waiting at most 400ms (see data sheet for further
> + * info).
> + * To avoid long busy wait we spin for few milliseconds then
> + * start sleeping. */

multi-line comment block format is not correct. It should be

> + /*
> + * Read ADC channel waiting at most 400ms (see data sheet for further
> + * info).
> + * To avoid long busy wait we spin for few milliseconds then
> + * start sleeping.
> + */

please change it to other places in driver also.

> + end = jiffies + msecs_to_jiffies(400);
> + while (time_before(jiffies, end)) {
> + i2c_smbus_write_byte(client, cmd);
> +
> + if (loop++ < 5)
> + mdelay(1);
> + else
> + msleep(1);
> +
> + ret = i2c_smbus_read_byte(client);
> + if (ret < 0)
> + return ret;
> + else if (ret & 0x0080)
> + break;
> + }
> + if (!(ret & 0x0080))
> + return -EIO;
> + return ((u8) ret) & 0x7f; /* remove the "valid" bit */
> +}
> +
> +/* --- LUX calculation ----------------------------------------------------- */
> +
> +#define TSL2550_MAX_LUX 1846
> +
> +static const u8 ratio_lut[] = {
> + 100, 100, 100, 100, 100, 100, 100, 100,
> + 100, 100, 100, 100, 100, 100, 99, 99,
> + 99, 99, 99, 99, 99, 99, 99, 99,
> + 99, 99, 99, 98, 98, 98, 98, 98,
> + 98, 98, 97, 97, 97, 97, 97, 96,
> + 96, 96, 96, 95, 95, 95, 94, 94,
> + 93, 93, 93, 92, 92, 91, 91, 90,
> + 89, 89, 88, 87, 87, 86, 85, 84,
> + 83, 82, 81, 80, 79, 78, 77, 75,
> + 74, 73, 71, 69, 68, 66, 64, 62,
> + 60, 58, 56, 54, 52, 49, 47, 44,
> + 42, 41, 40, 40, 39, 39, 38, 38,
> + 37, 37, 37, 36, 36, 36, 35, 35,
> + 35, 35, 34, 34, 34, 34, 33, 33,
> + 33, 33, 32, 32, 32, 32, 32, 31,
> + 31, 31, 31, 31, 30, 30, 30, 30,
> + 30,
> +};
> +
> +static const u16 count_lut[] = {
> + 0, 1, 2, 3, 4, 5, 6, 7,
> + 8, 9, 10, 11, 12, 13, 14, 15,
> + 16, 18, 20, 22, 24, 26, 28, 30,
> + 32, 34, 36, 38, 40, 42, 44, 46,
> + 49, 53, 57, 61, 65, 69, 73, 77,
> + 81, 85, 89, 93, 97, 101, 105, 109,
> + 115, 123, 131, 139, 147, 155, 163, 171,
> + 179, 187, 195, 203, 211, 219, 227, 235,
> + 247, 263, 279, 295, 311, 327, 343, 359,
> + 375, 391, 407, 423, 439, 455, 471, 487,
> + 511, 543, 575, 607, 639, 671, 703, 735,
> + 767, 799, 831, 863, 895, 927, 959, 991,
> + 1039, 1103, 1167, 1231, 1295, 1359, 1423, 1487,
> + 1551, 1615, 1679, 1743, 1807, 1871, 1935, 1999,
> + 2095, 2223, 2351, 2479, 2607, 2735, 2863, 2991,
> + 3119, 3247, 3375, 3503, 3631, 3759, 3887, 4015
> +};
> +
> +/* This function is described into Taos TSL2550 Designer's Notebook
> + * pages 2, 3 */
> +static int tsl2550_calculate_lux(u8 ch0, u8 ch1)
> +{
> + unsigned int lux;
> +
> + /* Look up count from channel values */
> + u16 c0 = count_lut[ch0];
> + u16 c1 = count_lut[ch1];
> +
> + /* Calculate ratio.
> + * Note: the "128" is a scaling factor */
> + u8 r = 128;
> +
> + /* Avoid division by 0 and count 1 cannot be greater than count 0 */
> + if (c0 && (c1 <= c0))
> + r = c1 * 128 / c0;
> + else
> + return -1;
> +
> + /* Calculare LUX */
> + lux = ((c0 - c1) * ratio_lut[r]) / 256;
> +
> + /* LUX range check */
> + return lux > TSL2550_MAX_LUX ? TSL2550_MAX_LUX : lux;
> +}
> +
> +/* --- SysFS support ------------------------------------------------------- */
> +
> +static ssize_t tsl2550_show_power_state(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> + struct tsl2550_data *data = i2c_get_clientdata(to_i2c_client(dev));
> +
> + return sprintf(buf, "%u\n", data->power_state);
> +}
> +
> +static ssize_t tsl2550_store_power_state(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
> +{
> + struct i2c_client *client = to_i2c_client(dev);
> + struct tsl2550_data *data = i2c_get_clientdata(client);
> + unsigned long val = simple_strtoul(buf, NULL, 10);
> + int ret;
> +
> + mutex_lock(&data->update_lock);
> + ret = tsl2550_set_power_state(client, val);
> + mutex_unlock(&data->update_lock);
> +
> + if (ret < 0)
> + return ret;
> +
> + return count;
> +}
> +
> +static DEVICE_ATTR(power_state, S_IWUSR | S_IRUGO,
> + tsl2550_show_power_state, tsl2550_store_power_state);
> +
> +static ssize_t tsl2550_show_operating_mode(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> + struct tsl2550_data *data = i2c_get_clientdata(to_i2c_client(dev));
> +
> + return sprintf(buf, "%u\n", data->operating_mode);
> +}
> +
> +static ssize_t tsl2550_store_operating_mode(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
> +{
> + struct i2c_client *client = to_i2c_client(dev);
> + struct tsl2550_data *data = i2c_get_clientdata(client);
> + unsigned long val = simple_strtoul(buf, NULL, 10);
> + int ret;
> +
> + mutex_lock(&data->update_lock);
> + ret = tsl2550_set_operating_mode(client, val);
> + mutex_unlock(&data->update_lock);
> +
> + if (ret < 0)
> + return ret;
> +
> + return count;
> +}
> +
> +static DEVICE_ATTR(operating_mode, S_IWUSR | S_IRUGO,
> + tsl2550_show_operating_mode, tsl2550_store_operating_mode);
> +
> +static ssize_t __tsl2550_show_lux(struct i2c_client *client, struct device_attribute *attr, char *buf)
> +{
> + u8 ch0, ch1;
> + int ret;
> +
> + ret = tsl2550_get_adc_value(client, 0);
> + if (ret < 0)
> + return ret;
> + ch0 = (u8) ret;
> +
> + mdelay(1);
> +
> + ret = tsl2550_get_adc_value(client, 1);
> + if (ret < 0)
> + return ret;
> + ch1 = (u8) ret;
> +
> + /* Do the job */
> + ret = tsl2550_calculate_lux(ch0, ch1);
> + if (ret < 0)
> + return ret;
> +
> + return sprintf(buf, "%u\n", ret);
> +}
> +
> +static ssize_t tsl2550_show_lux(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> + struct i2c_client *client = to_i2c_client(dev);
> + struct tsl2550_data *data = i2c_get_clientdata(client);
> + int ret;
> +
> + /* No LUX data if not operational */
> + if (!data->power_state)
> + return -EBUSY;
> +
> + mutex_lock(&data->update_lock);
> + ret = __tsl2550_show_lux(client, attr, buf);
> + mutex_unlock(&data->update_lock);
> +
> + return ret;
> +}
> +
> +static DEVICE_ATTR(lux, S_IRUGO,
> + tsl2550_show_lux, NULL);
> +
> +static struct attribute *tsl2550_attributes[] = {
> + &dev_attr_power_state.attr,
> + &dev_attr_operating_mode.attr,
> + &dev_attr_lux.attr,
> + NULL
> +};
> +
> +static const struct attribute_group tsl2550_attr_group = {
> + .attrs = tsl2550_attributes,
> +};
> +
> +/* --- Initialization function --------------------------------------------- */
> +
> +static void tsl2550_init_client(struct i2c_client *client)
> +{
> + struct tsl2550_data *data = i2c_get_clientdata(client);
> +
> + /* Power up the device and set the default operating mode */
> + tsl2550_set_power_state(client, 1);
> + tsl2550_set_operating_mode(client, data->operating_mode);
> +}
> +
> +/* --- I2C init/probing/exit functions ------------------------------------- */
> +
> +static struct i2c_driver tsl2550_driver;
> +static int __devinit tsl2550_probe(struct i2c_client *client)
> +{
> + struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
> + struct tsl2550_data *data;
> + int *opmode, err = 0;
> +
> + if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE
> + | I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
> + goto exit;

On "exit" you are returning value of "err" which is zero as per first
exit above. You should
first set "err" to relevant error flag and then exit.

> +
> + data = kzalloc(sizeof(struct tsl2550_data), GFP_KERNEL);
> + if (!data) {
> + err = -ENOMEM;
> + goto exit;
> + }
> + data->client = client;
> + strncpy(client->name, TSL2550_DRV_NAME, I2C_NAME_SIZE);

You can use "type" field in i2c_board_info structure to pass the
client's name. As this name is being copied to client->name by
i2c_new_device, and it could be useful in future to different next
version of the very much similar chips using this field.

> + i2c_set_clientdata(client, data);
> +
> + /* Check platform data */
> + opmode = client->dev.platform_data;
> + if (opmode) {
> + if (*opmode < 0 || *opmode > 1) {
> + dev_err(&client->dev, "invalid operating_mode (%d)\n",
> + *opmode);
> + err = -EINVAL;
> + goto exit_kfree;
> + }
> + data->operating_mode = *opmode;
> + }
> + else

"else" should be with closing "}" bracket not after that.

> + data->operating_mode = 0; /* default mode is standard */
> + dev_info(&client->dev, "%s operating mode\n",
> + data->operating_mode ? "extended" : "standard");
> +
> + /* Probe the chip. To do so we try to power up the device and then to
> + * read back the 0x03 code */
> + err = i2c_smbus_write_byte(client, TSL2550_POWER_UP);
> + if (err < 0)
> + goto exit_kfree;
> + mdelay(1);
> + err = i2c_smbus_read_byte(client);
> + if (err != TSL2550_POWER_UP) {
> + err = -ENODEV;
> + goto exit_kfree;
> + }
> +
> + mutex_init(&data->update_lock);
> +
> + /* Initialize the TSL2550 chip */
> + tsl2550_init_client(client);
> +
> + /* Register sysfs hooks */
> + err = sysfs_create_group(&client->dev.kobj, &tsl2550_attr_group);
> + if (err)
> + goto exit_kfree;
> +
> + dev_info(&client->dev,
> + "TSL2550 I2C support enabled - ver. %s\n", DRIVER_VERSION);
> + dev_info(&client->dev,
> + "Copyright (C) 2007 Rodolfo Giometti <giometti@linux.it>\n");
> +
> + return 0;
> +
> +exit_kfree:
> + kfree(data);
> +exit:
> + return err;
> +}
> +
> +static int __devexit tsl2550_remove(struct i2c_client *client)
> +{
> + sysfs_remove_group(&client->dev.kobj, &tsl2550_attr_group);
> +
> + /* Power doen the device */
> + tsl2550_set_power_state(client, 0);
> +
> + kfree(i2c_get_clientdata(client));
> +
> + return 0;
> +}
> +
> +static struct i2c_driver tsl2550_driver = {
> + .driver = {
> + .name = TSL2550_DRV_NAME,
> + .owner = THIS_MODULE,
> + },
> + .probe = tsl2550_probe,
> + .remove = __devexit_p(tsl2550_remove),
> +};
> +
> +static int __init tsl2550_init(void)
> +{
> + return i2c_add_driver(&tsl2550_driver);
> +}
> +
> +static void __exit tsl2550_exit(void)
> +{
> + i2c_del_driver(&tsl2550_driver);
> +}
> +
> +MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
> +MODULE_DESCRIPTION("TSL2550 ambient light sensor driver");
> +MODULE_LICENSE("GPL");
> +
> +module_init(tsl2550_init);
> +module_exit(tsl2550_exit);

--
--Trilok Soni