[PATCH v2 2/2] hwmon: (ads7828) add support for ADS7830

Vivien Didelot
2012-10-01T23:16:43Z

From: Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>

The ADS7830 device is almost the same as the ADS7828,
except that it does 8-bit sampling, instead of 12-bit.
This patch extends the ads7828 driver to support this chip.

Signed-off-by: Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
---
Documentation/hwmon/ads7828 | 12 ++++++++--
drivers/hwmon/Kconfig | 7 +++---
drivers/hwmon/ads7828.c | 58 ++++++++++++++++++++++++++++++++-------------
3 files changed, 55 insertions(+), 22 deletions(-)

diff --git a/Documentation/hwmon/ads7828 b/Documentation/hwmon/ads7828
index 2bbebe6..4366a87 100644
--- a/Documentation/hwmon/ads7828
+++ b/Documentation/hwmon/ads7828
@@ -8,8 +8,15 @@ Supported chips:
Datasheet: Publicly available at the Texas Instruments website :
http://focus.ti.com/lit/ds/symlink/ads7828.pdf

+ * Texas Instruments ADS7830
+ Prefix: 'ads7830'
+ Addresses scanned: I2C 0x48, 0x49, 0x4a, 0x4b
+ Datasheet: Publicly available at the Texas Instruments website:
+ http://focus.ti.com/lit/ds/symlink/ads7830.pdf
+
Authors:
Steve Hardy <shardy@redhat.com>
+ Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>

Module Parameters
-----------------
@@ -24,9 +31,10 @@ Module Parameters
Description
-----------

-This driver implements support for the Texas Instruments ADS7828.
+This driver implements support for the Texas Instruments ADS7828, and ADS7830.

-This device is a 12-bit 8-channel A-D converter.
+The ADS7828 device is a 12-bit 8-channel A/D converter, while the ADS7830 does
+8-bit sampling.

It can operate in single ended mode (8 +ve inputs) or in differential mode,
where 4 differential pairs can be measured.
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 83e3e9d..960c8c5 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1060,11 +1060,12 @@ config SENSORS_ADS1015
will be called ads1015.

config SENSORS_ADS7828
- tristate "Texas Instruments ADS7828"
+ tristate "Texas Instruments ADS7828 and compatibles"
depends on I2C
help
- If you say yes here you get support for Texas Instruments ADS7828
- 12-bit 8-channel ADC device.
+ If you say yes here you get support for Texas Instruments ADS7828 and
+ ADS7830 8-channel A/D converters. ADS7828 resolution is 12-bit, while
+ it is 8-bit on ADS7830.

This driver can also be built as a module. If so, the module
will be called ads7828.
diff --git a/drivers/hwmon/ads7828.c b/drivers/hwmon/ads7828.c
index fb3010d..91fc629 100644
--- a/drivers/hwmon/ads7828.c
+++ b/drivers/hwmon/ads7828.c
@@ -1,11 +1,13 @@
/*
- * ads7828.c - lm_sensors driver for ads7828 12-bit 8-channel ADC
+ * ads7828.c - driver for TI ADS7828 8-channel A/D converter and compatibles
* (C) 2007 EADS Astrium
*
* This driver is based on the lm75 and other lm_sensors/hwmon drivers
*
* Written by Steve Hardy <shardy@redhat.com>
*
+ * ADS7830 support by Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>
+ *
* For further information, see the Documentation/hwmon/ads7828 file.
*
* This program is free software; you can redistribute it and/or modify
@@ -41,6 +43,9 @@
#define ADS7828_CMD_PD3 0x0C /* Internal ref ON && A/D ON */
#define ADS7828_INT_VREF_MV 2500 /* Internal vref is 2.5V, 2500mV */

+/* List of supported devices */
+enum ads7828_chips { ads7828, ads7830 };
+
/* Addresses to scan */
static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
I2C_CLIENT_END };
@@ -53,9 +58,7 @@ module_param(se_input, bool, S_IRUGO);
module_param(int_vref, bool, S_IRUGO);
module_param(vref_mv, int, S_IRUGO);

-/* Global Variables */
static u8 ads7828_cmd_byte; /* cmd byte without channel bits */
-static unsigned int ads7828_lsb_resol; /* resolution of the ADC sample lsb */

/**
* struct ads7828_data - client specific data
@@ -64,6 +67,8 @@ static unsigned int ads7828_lsb_resol; /* resolution of the ADC sample lsb */
* @valid: Validity flag.
* @last_updated: Last updated time (in jiffies).
* @adc_input: ADS7828_NCH samples.
+ * @lsb_resol: Resolution of the A/D converter sample LSB.
+ * @read_channel: Function used to read a channel.
*/
struct ads7828_data {
struct device *hwmon_dev;
@@ -71,6 +76,8 @@ struct ads7828_data {
char valid;
unsigned long last_updated;
u16 adc_input[ADS7828_NCH];
+ unsigned int lsb_resol;
+ s32 (*read_channel)(const struct i2c_client *client, u8 command);
};

static inline u8 channel_cmd_byte(int ch)
@@ -96,8 +103,7 @@ static struct ads7828_data *ads7828_update_device(struct device *dev)

for (ch = 0; ch < ADS7828_NCH; ch++) {
u8 cmd = channel_cmd_byte(ch);
- data->adc_input[ch] =
- i2c_smbus_read_word_swapped(client, cmd);
+ data->adc_input[ch] = data->read_channel(client, cmd);
}
data->last_updated = jiffies;
data->valid = 1;
@@ -115,8 +121,8 @@ static ssize_t show_in(struct device *dev, struct device_attribute *da,
struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
struct ads7828_data *data = ads7828_update_device(dev);
/* Print value (in mV as specified in sysfs-interface documentation) */
- return sprintf(buf, "%d\n", (data->adc_input[attr->index] *
- ads7828_lsb_resol)/1000);
+ return sprintf(buf, "%d\n",
+ (data->adc_input[attr->index] * data->lsb_resol) / 1000);
}

#define in_reg(offset) \
@@ -162,6 +168,7 @@ static int ads7828_detect(struct i2c_client *client,
{
struct i2c_adapter *adapter = client->adapter;
int ch;
+ bool is_8bit = false;

/* Check we have a valid client */
if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA))
@@ -172,20 +179,30 @@ static int ads7828_detect(struct i2c_client *client,
* dedicated register so attempt to sanity check using knowledge of
* the chip
* - Read from the 8 channel addresses
- * - Check the top 4 bits of each result are not set (12 data bits)
+ * - Check the top 4 bits of each result:
+ * - They should not be set in case of 12-bit samples
+ * - The two bytes should be equal in case of 8-bit samples
*/
for (ch = 0; ch < ADS7828_NCH; ch++) {
u16 in_data;
u8 cmd = channel_cmd_byte(ch);
in_data = i2c_smbus_read_word_swapped(client, cmd);
if (in_data & 0xF000) {
- pr_debug("%s : Doesn't look like an ads7828 device\n",
- __func__);
- return -ENODEV;
+ if ((in_data >> 8) == (in_data & 0xFF)) {
+ /* Seems to be an ADS7830 (8-bit sample) */
+ is_8bit = true;
+ } else {
+ dev_dbg(&client->dev, "doesn't look like an "
+ "ADS7828 compatible device\n");
+ return -ENODEV;
+ }
}
}

- strlcpy(info->type, "ads7828", I2C_NAME_SIZE);
+ if (is_8bit)
+ strlcpy(info->type, "ads7830", I2C_NAME_SIZE);
+ else
+ strlcpy(info->type, "ads7828", I2C_NAME_SIZE);

return 0;
}
@@ -202,6 +219,15 @@ static int ads7828_probe(struct i2c_client *client,
goto exit;
}

+ /* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
+ if (id->driver_data == ads7828) {
+ data->read_channel = i2c_smbus_read_word_swapped;
+ data->lsb_resol = (vref_mv * 1000) / 4096;
+ } else {
+ data->read_channel = i2c_smbus_read_byte_data;
+ data->lsb_resol = (vref_mv * 1000) / 256;
+ }
+
i2c_set_clientdata(client, data);
mutex_init(&data->update_lock);

@@ -227,7 +253,8 @@ exit:
}

static const struct i2c_device_id ads7828_ids[] = {
- { "ads7828", 0 },
+ { "ads7828", ads7828 },
+ { "ads7830", ads7830 },
{ }
};
MODULE_DEVICE_TABLE(i2c, ads7828_ids);
@@ -250,9 +277,6 @@ static int __init sensors_ads7828_init(void)
ads7828_cmd_byte = se_input ? ADS7828_CMD_SD_SE : ADS7828_CMD_SD_DIFF;
ads7828_cmd_byte |= int_vref ? ADS7828_CMD_PD3 : ADS7828_CMD_PD1;

- /* Calculate the LSB resolution */
- ads7828_lsb_resol = (vref_mv*1000)/4096;
-
return i2c_add_driver(&ads7828_driver);
}

@@ -262,7 +286,7 @@ static void __exit sensors_ads7828_exit(void)
}

MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>");
-MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter");
+MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles");
MODULE_LICENSE("GPL");

module_init(sensors_ads7828_init);
--
1.7.11.4