MCP47x6 chip supports selection of a voltage reference (VDD, VREF buffered
or unbuffered). MCP4725 doesn't have this feature thus the setting is
ignored and user is warned if there is an attempt to set a value other than
zero.
The setting is stored only in the volatile memory of the chip. You need to
manually store it to the EEPROM of the chip via 'store_eeprom' sysfs entry.
Signed-off-by: Tomas Novotny <tomas@xxxxxxxxxx>
---
drivers/iio/dac/mcp4725.c | 45 +++++++++++++++++++++++++++++++++++++----
include/linux/iio/dac/mcp4725.h | 1 +
2 files changed, 42 insertions(+), 4 deletions(-)
diff --git a/drivers/iio/dac/mcp4725.c b/drivers/iio/dac/mcp4725.c
index cca935c..f8e54f1 100644
--- a/drivers/iio/dac/mcp4725.c
+++ b/drivers/iio/dac/mcp4725.c
@@ -28,7 +28,9 @@
struct mcp4725_data {
struct i2c_client *client;
+ int id;
u16 vref_mv;
+ unsigned vref_mode;
u16 dac_value;
bool powerdown;
unsigned powerdown_mode;
@@ -86,6 +88,7 @@ static ssize_t mcp4725_store_eeprom(struct device *dev,
return 0;
inoutbuf[0] = 0x60; /* write EEPROM */
+ inoutbuf[0] |= data->vref_mode << 3;
inoutbuf[1] = data->dac_value >> 4;
inoutbuf[2] = (data->dac_value & 0xf) << 4;
@@ -329,8 +332,10 @@ static int mcp4725_probe(struct i2c_client *client,
struct mcp4725_data *data;
struct iio_dev *indio_dev;
struct mcp4725_platform_data *platform_data = client->dev.platform_data;
- u8 inbuf[3];
+ u8 inoutbuf[3];
u8 pd;
+ u8 vref;
+ int ret;
int err;
if (!platform_data || !platform_data->vref_mv) {
@@ -344,6 +349,17 @@ static int mcp4725_probe(struct i2c_client *client,
data = iio_priv(indio_dev);
i2c_set_clientdata(client, indio_dev);
data->client = client;
+ data->id = id->driver_data;
+
+ if (data->id == MCP4725 && platform_data->vref_mode > 0) {
+ dev_warn(&client->dev, "vref mode is unavailable on MCP4725, ignoring");
+ platform_data->vref_mode = 0;
+ }
+
+ if (data->id == MCP4726 && platform_data->vref_mode > 3) {
+ dev_err(&client->dev, "vref mode is out of range");
+ return -EINVAL;
+ }
indio_dev->dev.parent = &client->dev;
indio_dev->name = id->name;
@@ -353,17 +369,38 @@ static int mcp4725_probe(struct i2c_client *client,
indio_dev->modes = INDIO_DIRECT_MODE;
data->vref_mv = platform_data->vref_mv;
+ data->vref_mode = platform_data->vref_mode;
/* read current DAC value */
- err = i2c_master_recv(client, inbuf, 3);
+ err = i2c_master_recv(client, inoutbuf, 3);
if (err < 0) {
dev_err(&client->dev, "failed to read DAC value");
return err;
}
- pd = (inbuf[0] >> 1) & 0x3;
+ pd = (inoutbuf[0] >> 1) & 0x3;
data->powerdown = pd > 0 ? true : false;
data->powerdown_mode = pd ? pd - 1 : 2; /* largest register to gnd */
- data->dac_value = (inbuf[1] << 4) | (inbuf[2] >> 4);
+ data->dac_value = (inoutbuf[1] << 4) | (inoutbuf[2] >> 4);
+ vref = inoutbuf[0] >> 3 & 0x3;
+
+ if (data->id == MCP4726 && vref != data->vref_mode) {
+ dev_info(&client->dev,
+ "vref_mode differs (conf: %d, eeprom: %d), setting %d",
+ data->vref_mode, vref, data->vref_mode);
+
+ inoutbuf[0] = 0x40;
+ inoutbuf[0] |= data->vref_mode << 3;
+ if (data->powerdown)
+ inoutbuf[0] |= data->powerdown << 1;
+ inoutbuf[1] = data->dac_value >> 4;
+ inoutbuf[2] = (data->dac_value & 0xf) << 4;
+
+ ret = i2c_master_send(data->client, inoutbuf, 3);
+ if (ret < 0)
+ return ret;
+ else if (ret != 3)
+ return -EIO;
+ }
return iio_device_register(indio_dev);
}
diff --git a/include/linux/iio/dac/mcp4725.h b/include/linux/iio/dac/mcp4725.h
index 91530e6..370022b 100644
--- a/include/linux/iio/dac/mcp4725.h
+++ b/include/linux/iio/dac/mcp4725.h
@@ -11,6 +11,7 @@
struct mcp4725_platform_data {
u16 vref_mv;
+ unsigned vref_mode;
};
#endif /* IIO_DAC_MCP4725_H_ */
--
2.1.4
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