[PATCH] TSL2550 support (I2C device driver)

[PATCH] TSL2550 support (I2C device driver)

[Rodolfo Giometti]

[-- Attachment #1: Type: text/plain, Size: 422 bytes --]

Hello,

attached a patch to add support for Taos TSL2550 ambient light sensors
(http://www.taosinc.com/product_detail.asp?cateid=4&proid=18).

Ciao,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail:    giometti@enneenne.com
Linux Device Driver                             giometti@gnudd.com
Embedded Systems                     		giometti@linux.it
UNIX programming                     phone:     +39 349 2432127

[-- Attachment #2: patch_tsl2550-support --]
[-- Type: text/plain, Size: 13906 bytes --]

diff --git a/drivers/i2c/chips/Kconfig b/drivers/i2c/chips/Kconfig
index 87ee3ce..18e60ec 100644
--- a/drivers/i2c/chips/Kconfig
+++ b/drivers/i2c/chips/Kconfig
@@ -125,4 +125,14 @@ 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..96b65ba
--- /dev/null
+++ b/drivers/i2c/chips/tsl2550.c
@@ -0,0 +1,445 @@
+/*
+ *  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>
+
+/* Address to scan */
+static unsigned short normal_i2c[] = { 0x39, I2C_CLIENT_END };
+
+/* Insmod parameters */
+I2C_CLIENT_INSMOD_1(tsl2550);
+
+static int operating_mode = 0;
+module_param(operating_mode, int, 0);
+MODULE_PARM_DESC(operating_mode,
+	"Operating mode: 0 = standard (default), 1 = extended");
+
+#define DRIVER_NAME     (tsl2550_driver.driver.name)
+#define DRIVER_VERSION  "1.0.0"
+
+/* --- 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;
+	int timeout, ret;
+
+	/* Read ADC channel waiting at most 400ms (see data sheet for further
+         * info) */
+	for (timeout = 400; timeout > 0; timeout--) {
+		i2c_smbus_write_byte(client, cmd);
+		mdelay(1);
+		ret = i2c_smbus_read_byte(client);
+		if (ret < 0)
+			return ret;
+		else if (ret & 0x0080)
+			break;
+	}
+	if (timeout == 0)
+		return -EIO;
+	return ((u8) ret) & 0x7f;	/* remove the "valid" bit */
+}
+
+/* --- LUX calculation ----------------------------------------------------- */
+
+#define	TSL2550_MAX_LUX		1846
+
+static 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 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)
+{
+	/* Power up the device and set the default operating mode */
+	tsl2550_set_power_state(client, 1);
+	tsl2550_set_operating_mode(client, operating_mode);
+}
+
+/* --- I2C init/probing/exit functions ------------------------------------- */
+
+static struct i2c_driver tsl2550_driver;
+static int tsl2550_detect(struct i2c_adapter *adapter, int address, int kind)
+{
+	struct i2c_client *new_client;
+	struct tsl2550_data *data;
+	int err = 0;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE
+				     | I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
+		goto exit;
+
+	/* OK. For now, we presume we have a valid client. We now create the
+	   client structure, even though we cannot fill it completely yet. */
+	if (!(data = kzalloc(sizeof(struct tsl2550_data), GFP_KERNEL))) {
+		err = -ENOMEM;
+		goto exit;
+	}
+	
+	new_client = &data->client;
+	i2c_set_clientdata(new_client, data);
+	new_client->addr = address;
+	new_client->adapter = adapter;
+	new_client->driver = &tsl2550_driver;
+	new_client->flags = 0;
+
+	/* 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(new_client, TSL2550_POWER_UP);
+	if (err < 0)
+		goto exit_kfree;
+	mdelay(1);
+	err = i2c_smbus_read_byte(new_client);
+	if (err != TSL2550_POWER_UP) {
+		err = -ENODEV;
+		goto exit_kfree;
+	}
+
+	/* Determine the chip type - only one kind supported! */
+	if (kind <= 0)
+		kind = tsl2550;
+
+	/* Fill in the remaining client fields and put it into the global 
+	   list */
+	strlcpy(new_client->name, "tsl2550", I2C_NAME_SIZE);
+	mutex_init(&data->update_lock);
+
+	/* Tell the I2C layer a new client has arrived */
+	if ((err = i2c_attach_client(new_client)))
+		goto exit_kfree;
+
+	/* Initialize the TSL2550 chip */
+	tsl2550_init_client(new_client);
+
+	/* Register sysfs hooks */
+	err = sysfs_create_group(&new_client->dev.kobj, &tsl2550_attr_group);
+	if (err)
+		goto exit_detach;
+
+	pr_info("%s: TSL2550 I2C support enabled - ver. %s\n",
+			DRIVER_NAME, DRIVER_VERSION);
+	pr_info("%s: Copyright (C) 2007 Rodolfo Giometti <giometti@linux.it>\n",
+			DRIVER_NAME);
+
+	return 0;
+
+exit_detach:
+	i2c_detach_client(new_client);
+exit_kfree:
+	kfree(data);
+exit:
+	return err;
+}
+
+static int tsl2550_attach_adapter(struct i2c_adapter *adapter)
+{
+	return i2c_probe(adapter, &addr_data, tsl2550_detect);
+}
+
+static int tsl2550_detach_client(struct i2c_client *client)
+{
+	int err;
+
+	sysfs_remove_group(&client->dev.kobj, &tsl2550_attr_group);
+
+	if ((err = i2c_detach_client(client)))
+		return err;
+
+	kfree(i2c_get_clientdata(client));
+
+	/* Power doen the device */
+	tsl2550_set_power_state(client, 0);
+
+	return 0;
+}
+
+static struct i2c_driver tsl2550_driver = {
+	.driver = {
+		.name	= "tsl2550",
+	},
+	.id		= I2C_DRIVERID_TSL2550,
+	.attach_adapter	= tsl2550_attach_adapter,
+	.detach_client	= tsl2550_detach_client,
+};
+
+static int __init tsl2550_init(void)
+{
+	if (operating_mode < 0 || operating_mode > 1) {
+		printk(KERN_WARNING "tsl2550: invalid operating_mode (%d)\n",
+		       operating_mode);
+		return -EINVAL;
+	}
+
+	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);
diff --git a/include/linux/i2c-id.h b/include/linux/i2c-id.h
index 0a8f750..83a9ab6 100644
--- a/include/linux/i2c-id.h
+++ b/include/linux/i2c-id.h
@@ -157,6 +157,7 @@
 #define I2C_DRIVERID_FSCHER 1046
 #define I2C_DRIVERID_W83L785TS 1047
 #define I2C_DRIVERID_OV7670 1048	/* Omnivision 7670 camera */
+#define I2C_DRIVERID_TSL2550 1049
 
 /*
  * ---- Adapter types ----------------------------------------------------

Re: [PATCH] TSL2550 support (I2C device driver)

[Andrew Morton]

On Tue, 30 Jan 2007 00:56:19 +0100
Rodolfo Giometti <giometti@enneenne.com> wrote:

> Hello,
> 
> attached a patch to add support for Taos TSL2550 ambient light sensors
> (http://www.taosinc.com/product_detail.asp?cateid=4&proid=18).
> 

Some minor things:

> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/slab.h>
> +#include <linux/i2c.h>
> +#include <linux/mutex.h>
> +#include <linux/delay.h>
> +
> +/* Address to scan */
> +static unsigned short normal_i2c[] = { 0x39, I2C_CLIENT_END };
> +
> +/* Insmod parameters */
> +I2C_CLIENT_INSMOD_1(tsl2550);
> +
> +static int operating_mode = 0;

The `= 0' is unneeded and undesirable.

> ...
>
> +static int tsl2550_get_adc_value(struct i2c_client *client, int channel)
> +{
> +	u8 cmd = channel == 0 ? TSL2550_READ_ADC0 : TSL2550_READ_ADC1;
> +	int timeout, ret;
> +
> +	/* Read ADC channel waiting at most 400ms (see data sheet for further
> +         * info) */
> +	for (timeout = 400; timeout > 0; timeout--) {
> +		i2c_smbus_write_byte(client, cmd);
> +		mdelay(1);
> +		ret = i2c_smbus_read_byte(client);
> +		if (ret < 0)
> +			return ret;
> +		else if (ret & 0x0080)
> +			break;
> +	}
> +	if (timeout == 0)
> +		return -EIO;
> +	return ((u8) ret) & 0x7f;	/* remove the "valid" bit */
> +}

eek.  Is there no way to avoid the busy-wait?  We cannot sleep here?

> +/* --- LUX calculation ----------------------------------------------------- */
> +
> +#define	TSL2550_MAX_LUX		1846
> +
> +static 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 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
> +};

These tables could perhaps be const?

> +static ssize_t tsl2550_show_power_state(struct device *dev, struct device_attribute *attr, char *buf)

It's preferred to try to fit the code into an 80-col window.  (But some
people disagree with this specifically for function definitions such as
this).

> +static ssize_t tsl2550_store_power_state(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)

Ditto (and other places).

> +static int tsl2550_detach_client(struct i2c_client *client)
> +{
> +	int err;
> +
> +	sysfs_remove_group(&client->dev.kobj, &tsl2550_attr_group);
> +
> +	if ((err = i2c_detach_client(client)))
> +		return err;

Preferred coding style is

	err = i2c_detach_client(client);
	if (err)
		return err;

(multiple places)

Re: [PATCH] TSL2550 support (I2C device driver)

[Andrew Morton]

On Mon, 29 Jan 2007 18:39:50 -0800
Andrew Morton <akpm@osdl.org> wrote:

> > attached a patch to add support for Taos TSL2550 ambient light sensors
> > (http://www.taosinc.com/product_detail.asp?cateid=4&proid=18).
> > 
> 
> Some minor things:

Oh, and please send a signoff for this work as per section 11 of
Documentation/SubmittingPatches, thanks.

Re: [PATCH] TSL2550 support (I2C device driver)

[Rodolfo Giometti]

On Mon, Jan 29, 2007 at 06:39:50PM -0800, Andrew Morton wrote:

> > +/* Insmod parameters */
> > +I2C_CLIENT_INSMOD_1(tsl2550);
> > +
> > +static int operating_mode = 0;
> 
> The `= 0' is unneeded and undesirable.

Fixed.

> > ...
> >
> > +static int tsl2550_get_adc_value(struct i2c_client *client, int channel)
> > +{
> > +	u8 cmd = channel == 0 ? TSL2550_READ_ADC0 : TSL2550_READ_ADC1;
> > +	int timeout, ret;
> > +
> > +	/* Read ADC channel waiting at most 400ms (see data sheet for further
> > +         * info) */
> > +	for (timeout = 400; timeout > 0; timeout--) {
> > +		i2c_smbus_write_byte(client, cmd);
> > +		mdelay(1);
> > +		ret = i2c_smbus_read_byte(client);
> > +		if (ret < 0)
> > +			return ret;
> > +		else if (ret & 0x0080)
> > +			break;
> > +	}
> > +	if (timeout == 0)
> > +		return -EIO;
> > +	return ((u8) ret) & 0x7f;	/* remove the "valid" bit */
> > +}
> 
> eek.  Is there no way to avoid the busy-wait?  We cannot sleep here?

That's why I have to retry reading data for at most 400ms otherwise
the chip will start a new ADC conversion.

I can replace mdelay(1) with schedule_timeout(HZ/1000) but doing this
I'm not sure that just 1ms has elapesed. Also the chip has no irq
lines to use for that.

> > +/* --- LUX calculation ----------------------------------------------------- */
> > +
> > +#define	TSL2550_MAX_LUX		1846
> > +
> > +static u8 ratio_lut[] = {
> > +	100, 100, 100, 100, 100, 100, 100, 100, 
> > [snip]
> > +
> > +static u16 count_lut[] = {
> > +	0, 1, 2, 3, 4, 5, 6, 7, 
> > [snip]
> 
> These tables could perhaps be const?

Fixed.

> > +static ssize_t tsl2550_show_power_state(struct device *dev, struct device_attribute *attr, char *buf)
> 
> It's preferred to try to fit the code into an 80-col window.  (But some
> people disagree with this specifically for function definitions such as
> this).

I agree with them. :)

> Preferred coding style is
> 
> 	err = i2c_detach_client(client);
> 	if (err)
> 		return err;
> 
> (multiple places)

Fixed.

I'm going to repost the patch after some tests.

Thanks,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail:    giometti@enneenne.com
Linux Device Driver                             giometti@gnudd.com
Embedded Systems                     		giometti@linux.it
UNIX programming                     phone:     +39 349 2432127

Re: [PATCH] TSL2550 support (I2C device driver)

[Andrew Morton]

On Tue, 30 Jan 2007 11:26:42 +0100
Rodolfo Giometti <giometti@enneenne.com> wrote:

> > > +static int tsl2550_get_adc_value(struct i2c_client *client, int channel)
> > > +{
> > > +	u8 cmd = channel == 0 ? TSL2550_READ_ADC0 : TSL2550_READ_ADC1;
> > > +	int timeout, ret;
> > > +
> > > +	/* Read ADC channel waiting at most 400ms (see data sheet for further
> > > +         * info) */
> > > +	for (timeout = 400; timeout > 0; timeout--) {
> > > +		i2c_smbus_write_byte(client, cmd);
> > > +		mdelay(1);
> > > +		ret = i2c_smbus_read_byte(client);
> > > +		if (ret < 0)
> > > +			return ret;
> > > +		else if (ret & 0x0080)
> > > +			break;
> > > +	}
> > > +	if (timeout == 0)
> > > +		return -EIO;
> > > +	return ((u8) ret) & 0x7f;	/* remove the "valid" bit */
> > > +}
> > 
> > eek.  Is there no way to avoid the busy-wait?  We cannot sleep here?
> 
> That's why I have to retry reading data for at most 400ms otherwise
> the chip will start a new ADC conversion.
> 
> I can replace mdelay(1) with schedule_timeout(HZ/1000) but doing this
> I'm not sure that just 1ms has elapesed. Also the chip has no irq
> lines to use for that.

I expect an msleep(1) will be OK, if you can indeed sleep on this
codepath.  Yes, that can delay for longer: ten milliseconds for sure
if HZ=100.

If that's a problem I guess you could spin for a millisecond or two, then
start sleeping:

	end = jiffies + msecs_to_jiffies(400);
	while (time_before(jiffies, end)) {
		loop++;
		...
		if (loop < 5)
			mdelay(1);
		else
			msleep(1);
	}

or something like that.

[PATCH 001/001] I2C: TSL2550 support

[Rodolfo Giometti]

[-- Attachment #1: Type: text/plain, Size: 172 bytes --]

From: Rodolfo Giometti <giometti@enneenne.com>

Patch to add support for Taos TSL2550 ambient light sensors.

Signed-off-by: Rodolfo Giometti <giometti@enneenne.com>

---


[-- Attachment #2: patch_tsl2550-support --]
[-- Type: text/plain, Size: 14122 bytes --]

diff --git a/drivers/i2c/chips/Kconfig b/drivers/i2c/chips/Kconfig
index 87ee3ce..18e60ec 100644
--- a/drivers/i2c/chips/Kconfig
+++ b/drivers/i2c/chips/Kconfig
@@ -125,4 +125,14 @@ 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..4d75fc2
--- /dev/null
+++ b/drivers/i2c/chips/tsl2550.c
@@ -0,0 +1,457 @@
+/*
+ *  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>
+
+/* Address to scan */
+static unsigned short normal_i2c[] = { 0x39, I2C_CLIENT_END };
+
+/* Insmod parameters */
+I2C_CLIENT_INSMOD_1(tsl2550);
+
+static int operating_mode;
+module_param(operating_mode, int, 0);
+MODULE_PARM_DESC(operating_mode,
+	"Operating mode: 0 = standard (default), 1 = extended");
+
+#define DRIVER_NAME     (tsl2550_driver.driver.name)
+#define DRIVER_VERSION  "1.0.0"
+
+/* --- 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. */
+	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)
+{
+	/* Power up the device and set the default operating mode */
+	tsl2550_set_power_state(client, 1);
+	tsl2550_set_operating_mode(client, operating_mode);
+}
+
+/* --- I2C init/probing/exit functions ------------------------------------- */
+
+static struct i2c_driver tsl2550_driver;
+static int tsl2550_detect(struct i2c_adapter *adapter, int address, int kind)
+{
+	struct i2c_client *new_client;
+	struct tsl2550_data *data;
+	int err = 0;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE
+				     | I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
+		goto exit;
+
+	/* OK. For now, we presume we have a valid client. We now create the
+	   client structure, even though we cannot fill it completely yet. */
+	data = kzalloc(sizeof(struct tsl2550_data), GFP_KERNEL);
+	if (!data) {
+		err = -ENOMEM;
+		goto exit;
+	}
+	
+	new_client = &data->client;
+	i2c_set_clientdata(new_client, data);
+	new_client->addr = address;
+	new_client->adapter = adapter;
+	new_client->driver = &tsl2550_driver;
+	new_client->flags = 0;
+
+	/* 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(new_client, TSL2550_POWER_UP);
+	if (err < 0)
+		goto exit_kfree;
+	mdelay(1);
+	err = i2c_smbus_read_byte(new_client);
+	if (err != TSL2550_POWER_UP) {
+		err = -ENODEV;
+		goto exit_kfree;
+	}
+
+	/* Determine the chip type - only one kind supported! */
+	if (kind <= 0)
+		kind = tsl2550;
+
+	/* Fill in the remaining client fields and put it into the global 
+	   list */
+	strlcpy(new_client->name, "tsl2550", I2C_NAME_SIZE);
+	mutex_init(&data->update_lock);
+
+	/* Tell the I2C layer a new client has arrived */
+	err = i2c_attach_client(new_client);
+	if (err)
+		goto exit_kfree;
+
+	/* Initialize the TSL2550 chip */
+	tsl2550_init_client(new_client);
+
+	/* Register sysfs hooks */
+	err = sysfs_create_group(&new_client->dev.kobj, &tsl2550_attr_group);
+	if (err)
+		goto exit_detach;
+
+	pr_info("%s: TSL2550 I2C support enabled - ver. %s\n",
+			DRIVER_NAME, DRIVER_VERSION);
+	pr_info("%s: Copyright (C) 2007 Rodolfo Giometti <giometti@linux.it>\n",
+			DRIVER_NAME);
+
+	return 0;
+
+exit_detach:
+	i2c_detach_client(new_client);
+exit_kfree:
+	kfree(data);
+exit:
+	return err;
+}
+
+static int tsl2550_attach_adapter(struct i2c_adapter *adapter)
+{
+	return i2c_probe(adapter, &addr_data, tsl2550_detect);
+}
+
+static int tsl2550_detach_client(struct i2c_client *client)
+{
+	int err;
+
+	sysfs_remove_group(&client->dev.kobj, &tsl2550_attr_group);
+
+	err = i2c_detach_client(client);
+	if (err)
+		return err;
+
+	kfree(i2c_get_clientdata(client));
+
+	/* Power doen the device */
+	tsl2550_set_power_state(client, 0);
+
+	return 0;
+}
+
+static struct i2c_driver tsl2550_driver = {
+	.driver = {
+		.name	= "tsl2550",
+	},
+	.id		= I2C_DRIVERID_TSL2550,
+	.attach_adapter	= tsl2550_attach_adapter,
+	.detach_client	= tsl2550_detach_client,
+};
+
+static int __init tsl2550_init(void)
+{
+	if (operating_mode < 0 || operating_mode > 1) {
+		printk(KERN_WARNING "tsl2550: invalid operating_mode (%d)\n",
+		       operating_mode);
+		return -EINVAL;
+	}
+
+	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);
diff --git a/include/linux/i2c-id.h b/include/linux/i2c-id.h
index b2e83df..344c42c 100644
--- a/include/linux/i2c-id.h
+++ b/include/linux/i2c-id.h
@@ -160,6 +160,7 @@
 #define I2C_DRIVERID_FSCHER 1046
 #define I2C_DRIVERID_W83L785TS 1047
 #define I2C_DRIVERID_OV7670 1048	/* Omnivision 7670 camera */
+#define I2C_DRIVERID_TSL2550 1049
 
 /*
  * ---- Adapter types ----------------------------------------------------