iio: dac: mcp4725: Add basic support for MCP4726

MCP4726 is a single channel 12-bit DAC.  We can support MCP4726 with
a little changes to mcp4725 driver.  In power-down mode, they have
different selection of VOUT pull-down registers.

MCP4726 also has features:
 - Output gain options: 1x, 2x
 - Voltage reference selection: VDD, VREF (Unbuffered or Buffered)

But these are not supported in this change. (1x gain, VDD is selected)

datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/22272C.pdf

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Hartmut Knaack <knaack.h@gmx.de>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Peter Meerwald <pmeerw@pmeerw.net>
Cc: linux-iio@vger.kernel.org
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

3 files changed, 71 insertions, 22 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index 0439c2aaf741..8fadd272ad8a 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -497,7 +497,9 @@ Description:
                 6kohm_to_gnd: connected to ground via a 6kOhm resistor,
                 20kohm_to_gnd: connected to ground via a 20kOhm resistor,
                 100kohm_to_gnd: connected to ground via an 100kOhm resistor,
+                125kohm_to_gnd: connected to ground via an 125kOhm resistor,
                 500kohm_to_gnd: connected to ground via a 500kOhm resistor,
+                640kohm_to_gnd: connected to ground via a 640kOhm resistor,
                 three_state: left floating.
                 For a list of available output power down options read
                 outX_powerdown_mode_available. If Y is not present the
diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index e701e28fb1cd..5263c5125fbb 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -176,11 +176,11 @@ config MAX5821
           10 bits DAC.
 
 config MCP4725
-        tristate "MCP4725 DAC driver"
+        tristate "MCP4725/6 DAC driver"
         depends on I2C
         ---help---
           Say Y here if you want to build a driver for the Microchip
-          MCP 4725 12-bit digital-to-analog converter (DAC) with I2C
+          MCP 4725/6 12-bit digital-to-analog converter (DAC) with I2C
           interface.
 
           To compile this driver as a module, choose M here: the module
diff --git a/drivers/iio/dac/mcp4725.c b/drivers/iio/dac/mcp4725.c
index 43d14588448d..fb4b3364d8e0 100644
--- a/drivers/iio/dac/mcp4725.c
+++ b/drivers/iio/dac/mcp4725.c
@@ -1,5 +1,5 @@
 /*
- * mcp4725.c - Support for Microchip MCP4725
+ * mcp4725.c - Support for Microchip MCP4725/6
  *
  * Copyright (C) 2012 Peter Meerwald <pmeerw@pmeerw.net>
  *
@@ -134,6 +134,12 @@ static const char * const mcp4725_powerdown_modes[] = {
         "500kohm_to_gnd"
 };
 
+static const char * const mcp4726_powerdown_modes[] = {
+        "1kohm_to_gnd",
+        "125kohm_to_gnd",
+        "640kohm_to_gnd"
+};
+
 static int mcp4725_get_powerdown_mode(struct iio_dev *indio_dev,
         const struct iio_chan_spec *chan)
 {
@@ -182,11 +188,24 @@ static ssize_t mcp4725_write_powerdown(struct iio_dev *indio_dev,
         return len;
 }
 
-static const struct iio_enum mcp4725_powerdown_mode_enum = {
-        .items = mcp4725_powerdown_modes,
-        .num_items = ARRAY_SIZE(mcp4725_powerdown_modes),
-        .get = mcp4725_get_powerdown_mode,
-        .set = mcp4725_set_powerdown_mode,
+enum {
+        MCP4725,
+        MCP4726,
+};
+
+static const struct iio_enum mcp472x_powerdown_mode_enum[] = {
+        [MCP4725] = {
+                .items = mcp4725_powerdown_modes,
+                .num_items = ARRAY_SIZE(mcp4725_powerdown_modes),
+                .get = mcp4725_get_powerdown_mode,
+                .set = mcp4725_set_powerdown_mode,
+        },
+        [MCP4726] = {
+                .items = mcp4726_powerdown_modes,
+                .num_items = ARRAY_SIZE(mcp4726_powerdown_modes),
+                .get = mcp4725_get_powerdown_mode,
+                .set = mcp4725_set_powerdown_mode,
+        },
 };
 
 static const struct iio_chan_spec_ext_info mcp4725_ext_info[] = {
@@ -196,19 +215,46 @@ static const struct iio_chan_spec_ext_info mcp4725_ext_info[] = {
                 .write = mcp4725_write_powerdown,
                 .shared = IIO_SEPARATE,
         },
-        IIO_ENUM("powerdown_mode", IIO_SEPARATE, &mcp4725_powerdown_mode_enum),
-        IIO_ENUM_AVAILABLE("powerdown_mode", &mcp4725_powerdown_mode_enum),
+        IIO_ENUM("powerdown_mode", IIO_SEPARATE,
+                        &mcp472x_powerdown_mode_enum[MCP4725]),
+        IIO_ENUM_AVAILABLE("powerdown_mode",
+                        &mcp472x_powerdown_mode_enum[MCP4725]),
+        { },
+};
+
+static const struct iio_chan_spec_ext_info mcp4726_ext_info[] = {
+        {
+                .name = "powerdown",
+                .read = mcp4725_read_powerdown,
+                .write = mcp4725_write_powerdown,
+                .shared = IIO_SEPARATE,
+        },
+        IIO_ENUM("powerdown_mode", IIO_SEPARATE,
+                        &mcp472x_powerdown_mode_enum[MCP4726]),
+        IIO_ENUM_AVAILABLE("powerdown_mode",
+                        &mcp472x_powerdown_mode_enum[MCP4726]),
         { },
 };
 
-static const struct iio_chan_spec mcp4725_channel = {
-        .type           = IIO_VOLTAGE,
-        .indexed        = 1,
-        .output         = 1,
-        .channel        = 0,
-        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
-        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
-        .ext_info       = mcp4725_ext_info,
+static const struct iio_chan_spec mcp472x_channel[] = {
+        [MCP4725] = {
+                .type           = IIO_VOLTAGE,
+                .indexed        = 1,
+                .output         = 1,
+                .channel        = 0,
+                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+                .ext_info       = mcp4725_ext_info,
+        },
+        [MCP4726] = {
+                .type           = IIO_VOLTAGE,
+                .indexed        = 1,
+                .output         = 1,
+                .channel        = 0,
+                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+                .ext_info       = mcp4726_ext_info,
+        },
 };
 
 static int mcp4725_set_value(struct iio_dev *indio_dev, int val)
@@ -301,7 +347,7 @@ static int mcp4725_probe(struct i2c_client *client,
 
         indio_dev->dev.parent = &client->dev;
         indio_dev->info = &mcp4725_info;
-        indio_dev->channels = &mcp4725_channel;
+        indio_dev->channels = &mcp472x_channel[id->driver_data];
         indio_dev->num_channels = 1;
         indio_dev->modes = INDIO_DIRECT_MODE;
 
@@ -315,7 +361,7 @@ static int mcp4725_probe(struct i2c_client *client,
         }
         pd = (inbuf[0] >> 1) & 0x3;
         data->powerdown = pd > 0 ? true : false;
-        data->powerdown_mode = pd ? pd-1 : 2; /* 500kohm_to_gnd */
+        data->powerdown_mode = pd ? pd - 1 : 2; /* largest register to gnd */
         data->dac_value = (inbuf[1] << 4) | (inbuf[2] >> 4);
 
         return iio_device_register(indio_dev);
@@ -328,7 +374,8 @@ static int mcp4725_remove(struct i2c_client *client)
 }
 
 static const struct i2c_device_id mcp4725_id[] = {
-        { "mcp4725", 0 },
+        { "mcp4725", MCP4725 },
+        { "mcp4726", MCP4726 },
         { }
 };
 MODULE_DEVICE_TABLE(i2c, mcp4725_id);
@@ -345,5 +392,5 @@ static struct i2c_driver mcp4725_driver = {
 module_i2c_driver(mcp4725_driver);
 
 MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
-MODULE_DESCRIPTION("MCP4725 12-bit DAC");
+MODULE_DESCRIPTION("MCP4725/6 12-bit DAC");
 MODULE_LICENSE("GPL");