Microchip MCP4728 is a 12-bit quad channel
digital-to-analog converter (DAC) with I2C interface.
This patch adds support for most of the features of MCP4728,
including per-channel gain, power state and power down mode control.
Driver also supports saving the current state to on-chip EEPROM.
At present, only internal voltage reference is supported.
Signed-off-by: Evgeny Boger <boger@xxxxxxxxxxxxxx>
---
drivers/iio/dac/Kconfig | 11 +
drivers/iio/dac/Makefile | 1 +
drivers/iio/dac/mcp4728.c | 479 ++++++++++++++++++++++++++++++++++++++++
include/linux/iio/dac/mcp4728.h | 16 ++
4 files changed, 507 insertions(+)
create mode 100644 drivers/iio/dac/mcp4728.c
create mode 100644 include/linux/iio/dac/mcp4728.h
diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index e701e28..8da6039 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -186,6 +186,17 @@ config MCP4725
To compile this driver as a module, choose M here: the module
will be called mcp4725.
+config MCP4728
+ tristate "MCP4728 DAC driver"
+ depends on I2C
+ ---help---
+ Say Y here if you want to build a driver for the Microchip
+ MCP 4728 12-bit quad digital-to-analog converter (DAC) with I2C
+ interface.
+
+ To compile this driver as a module, choose M here: the module
+ will be called mcp4728.
+
config MCP4922
tristate "MCP4902, MCP4912, MCP4922 DAC driver"
depends on SPI
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index 63ae056..2c9decc 100644
--- a/drivers/iio/dac/Makefile
+++ b/drivers/iio/dac/Makefile
@@ -20,4 +20,5 @@ obj-$(CONFIG_M62332) += m62332.o
obj-$(CONFIG_MAX517) += max517.o
obj-$(CONFIG_MAX5821) += max5821.o
obj-$(CONFIG_MCP4725) += mcp4725.o
+obj-$(CONFIG_MCP4728) += mcp4728.o
obj-$(CONFIG_MCP4922) += mcp4922.o
diff --git a/drivers/iio/dac/mcp4728.c b/drivers/iio/dac/mcp4728.c
new file mode 100644
index 0000000..6dbbfac
--- /dev/null
+++ b/drivers/iio/dac/mcp4728.c
@@ -0,0 +1,479 @@
+/*
+ * mcp4728.c - Support for Microchip MCP4728
+ *
+ * Copyright (C) 2016 Evgeny Boger <boger@xxxxxxxxxxxxxx>
+ *
+ * Based on mcp4728 by Peter Meerwald <pmeerw@xxxxxxxxxx>
+ *
+ * This file is subject to the terms and conditions of version 2 of
+ * the GNU General Public License. See the file COPYING in the main
+ * directory of this archive for more details.
+ *
+ * driver for the Microchip MCP4728 I2C 12-bit quad digital-to-analog
+ * converter (DAC)
+ * (7-bit I2C slave address 0x60, the three LSBs can be configured in
+ * hardware)
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/err.h>
+#include <linux/delay.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#include <linux/iio/dac/mcp4728.h>
+
+#define MCP4728_DRV_NAME "mcp4728"
+#define MCP4728_NUM_CHANNELS 4
+#define MCP4728_INT_VREF_MV 2048
+#define MCP4728_RESOLUTION 12
+
+struct mcp4728_scale {
+ unsigned int integer;
+ unsigned int micro;
+};
+
+struct mcp4728_channel_state {
+ u16 dac_value;
+ bool powerdown;
+ u8 gain;
+ u8 vref;
+ unsigned powerdown_mode;
+};
+
+struct mcp4728_data {
+ struct i2c_client *client;
+ struct mcp4728_channel_state channel_state[MCP4728_NUM_CHANNELS];
+ struct mcp4728_scale scale_avail[MCP4728_NUM_CHANNELS][2];
+
+};
+
+static int mcp4728_write_reg(struct mcp4728_data *data, int ch, bool eeprom)
+{
+ struct mcp4728_channel_state *state = &data->channel_state[ch];
+ u8 outbuf[3];
+ u8 pd;
+ int ret;
+
+ if (state->dac_value >= (1 << MCP4728_RESOLUTION) ||
+ state->dac_value < 0)
+ return -EINVAL;
+/*
+ Write input register. EEPROM is not updated:
+ c2=0, c1=1, c0=0, w1=0, w0=0 : 0x40
+
+ Write input and EEPROM registers:
+ c2=0, c1=1, c0=0, w1=1, w0=1 : 0x58
+
+ b[0]: c2 | c1 | c0 | w1 | w0 | dac1 | dac0 | /udac
+ b[1]: vref | pd1 | pd0 | gain | d11 | d10 | d9 | d8
+ b[2]: d7-d0
+*/
+ pd = state->powerdown ? (state->powerdown_mode + 1) : 0;
+
+ outbuf[0] = (eeprom ? 0x58 : 0x40) |
+ ((ch & 0x03) << 1);
+ outbuf[1] = ((state->vref & 0x01) << 7) |
+ ((pd & 0x3) << 5) |
+ ((state->gain & 0x01) << 4) |
+ ((state->dac_value >> 8) & 0x0f);
+ outbuf[2] = state->dac_value & 0xff;
+
+ ret = i2c_master_send(data->client, outbuf, 3);
+ if (ret < 0)
+ return ret;
+ else if (ret != 3)
+ return -EIO;
+ else
+ return 0;
+}
+
+static int mcp4728_write_input_reg(struct mcp4728_data *data, int ch)
+{
+ return mcp4728_write_reg(data, ch, false);
+}
+
+static int mcp4728_suspend(struct device *dev)
+{
+ struct mcp4728_data *data = iio_priv(i2c_get_clientdata(
+ to_i2c_client(dev)));
+ int ch, ret;
+
+ for (ch = 0; ch < MCP4728_NUM_CHANNELS; ++ch) {
+ data->channel_state[ch].powerdown = true;
+ ret = mcp4728_write_input_reg(data, ch);
+ if (ret < 0)
+ return ret;
+ }
+
+ return ret;
+}
+
+static int mcp4728_resume(struct device *dev)
+{
+ struct mcp4728_data *data = iio_priv(i2c_get_clientdata(
+ to_i2c_client(dev)));
+ int ch, ret;
+
+ for (ch = 0; ch < MCP4728_NUM_CHANNELS; ++ch) {
+ data->channel_state[ch].powerdown = false;
+ ret = mcp4728_write_input_reg(data, ch);
+ if (ret < 0)
+ return ret;
+ }
+
+ return ret;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static SIMPLE_DEV_PM_OPS(mcp4728_pm_ops, mcp4728_suspend, mcp4728_resume);
+#define MCP4728_PM_OPS (&mcp4728_pm_ops)
+#else
+#define MCP4728_PM_OPS NULL
+#endif
+
+static ssize_t mcp4728_store_eeprom(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t len)
+{
+ struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+ struct mcp4728_data *data = iio_priv(indio_dev);
+ int tries;
+ u8 inbuf[3];
+ bool state;
+ int ret, ch;
+
+ ret = strtobool(buf, &state);
+ if (ret < 0)
+ return ret;
+
+ if (!state)
+ return 0;
+
+ for (ch = 0; ch < MCP4728_NUM_CHANNELS; ++ch) {
+ tries = 20;
+ mcp4728_write_reg(data, ch, true);
+
+
+ /* wait for write complete, takes up to 50ms */
+ while (tries--) {
+ msleep(20);
+ ret = i2c_master_recv(data->client, inbuf, 1);
+ if (ret < 0)
+ return ret;
+ else if (ret != 1)
+ return -EIO;
+
+ if (inbuf[0] & 0x80)
+ break;
+ }
+
+ if (tries < 0) {
+ dev_err(&data->client->dev,
+ "mcp4728_store_eeprom() failed, incomplete\n");
+ return -EIO;
+ }
+ }
+
+ return len;
+}
+
+static IIO_DEVICE_ATTR(store_eeprom, S_IWUSR, NULL, mcp4728_store_eeprom, 0);
+
+
+static ssize_t mcp4728_show_scale_available(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct iio_dev_attr *iio_attr = to_iio_dev_attr(attr);
+ struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+ struct mcp4728_data *data = iio_priv(indio_dev);
+ u8 ch = iio_attr->address;
+ int i, len = 0;
+
+ for (i = 0; i < ARRAY_SIZE(data->scale_avail[ch]); i++)
+ len += sprintf(buf + len, "%u.%06u ",
+ data->scale_avail[ch][i].integer,
+ data->scale_avail[ch][i].micro);
+
+ len += sprintf(buf + len, "\n");
+
+ return len;
+}
+
+#define SHOW_SCALE_AVAILABLE_ATTR(ch) \
+static IIO_DEVICE_ATTR(out_voltage##ch##_scale_available, S_IRUGO, \
+ mcp4728_show_scale_available, NULL, ch)
+
+SHOW_SCALE_AVAILABLE_ATTR(0);
+SHOW_SCALE_AVAILABLE_ATTR(1);
+SHOW_SCALE_AVAILABLE_ATTR(2);
+SHOW_SCALE_AVAILABLE_ATTR(3);
+
+static struct attribute *mcp4728_attributes[] = {
+ &iio_dev_attr_store_eeprom.dev_attr.attr,
+ &iio_dev_attr_out_voltage0_scale_available.dev_attr.attr,
+ &iio_dev_attr_out_voltage1_scale_available.dev_attr.attr,
+ &iio_dev_attr_out_voltage2_scale_available.dev_attr.attr,
+ &iio_dev_attr_out_voltage3_scale_available.dev_attr.attr,
+ NULL,
+};
+
+static const struct attribute_group mcp4728_attribute_group = {
+ .attrs = mcp4728_attributes,
+};
+
+static const char * const mcp4728_powerdown_modes[] = {
+ "1kohm_to_gnd",
+ "100kohm_to_gnd",
+ "500kohm_to_gnd"
+};
+
+static int mcp4728_get_powerdown_mode(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan)
+{
+ struct mcp4728_data *data = iio_priv(indio_dev);
+
+ return data->channel_state[chan->channel].powerdown_mode;
+}
+
+static int mcp4728_set_powerdown_mode(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan, unsigned mode)
+{
+ struct mcp4728_data *data = iio_priv(indio_dev);
+
+ data->channel_state[chan->channel].powerdown_mode = mode;
+
+ return 0;
+}
+
+static ssize_t mcp4728_read_powerdown(struct iio_dev *indio_dev,
+ uintptr_t private, const struct iio_chan_spec *chan, char *buf)
+{
+ struct mcp4728_data *data = iio_priv(indio_dev);
+
+ return sprintf(buf, "%d\n",
+ data->channel_state[chan->channel].powerdown);
+}
+
+static ssize_t mcp4728_write_powerdown(struct iio_dev *indio_dev,
+ uintptr_t private, const struct iio_chan_spec *chan,
+ const char *buf, size_t len)
+{
+ struct mcp4728_data *data = iio_priv(indio_dev);
+ struct mcp4728_channel_state *state =
+ &data->channel_state[chan->channel];
+ bool powerdown;
+ int ret;
+
+ ret = strtobool(buf, &powerdown);
+ if (ret)
+ return ret;
+
+ state->powerdown = powerdown;
+ ret = mcp4728_write_input_reg(data, chan->channel);
+
+ if (ret < 0)
+ return ret;
+
+ return len;
+}
+
+static const struct iio_enum mcp4728_powerdown_mode_enum = {
+ .items = mcp4728_powerdown_modes,
+ .num_items = ARRAY_SIZE(mcp4728_powerdown_modes),
+ .get = mcp4728_get_powerdown_mode,
+ .set = mcp4728_set_powerdown_mode,
+};
+
+static const struct iio_chan_spec_ext_info mcp4728_ext_info[] = {
+ {
+ .name = "powerdown",
+ .read = mcp4728_read_powerdown,
+ .write = mcp4728_write_powerdown,
+ .shared = IIO_SEPARATE,
+ },
+ IIO_ENUM("powerdown_mode", IIO_SEPARATE, &mcp4728_powerdown_mode_enum),
+ IIO_ENUM_AVAILABLE("powerdown_mode", &mcp4728_powerdown_mode_enum),
+ { },
+};
+
+#define MCP4728_CHAN(chan) { \
+ .type = IIO_VOLTAGE, \
+ .indexed = 1, \
+ .output = 1, \
+ .channel = chan, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
+ BIT(IIO_CHAN_INFO_SCALE), \
+ .ext_info = mcp4728_ext_info, \
+}
+
+
+static const struct iio_chan_spec mcp4728_channels[MCP4728_NUM_CHANNELS] = {
+ MCP4728_CHAN(0),
+ MCP4728_CHAN(1),
+ MCP4728_CHAN(2),
+ MCP4728_CHAN(3),
+};
+
+static int mcp4728_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ struct mcp4728_data *data = iio_priv(indio_dev);
+ struct mcp4728_channel_state *state =
+ &data->channel_state[chan->channel];
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ *val = data->channel_state[chan->channel].dac_value;
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_SCALE:
+ *val = (state->gain + 1) * MCP4728_INT_VREF_MV;
+ *val2 = MCP4728_RESOLUTION;
+ return IIO_VAL_FRACTIONAL_LOG2;
+ }
+ return -EINVAL;
+}
+
+static int mcp4728_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int val, int val2, long mask)
+{
+ struct mcp4728_data *data = iio_priv(indio_dev);
+ struct mcp4728_channel_state *state =
+ &data->channel_state[chan->channel];
+ struct mcp4728_scale *scale_avail =
+ data->scale_avail[chan->channel];
+
+ int ret, gain;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ state->dac_value = val;
+ ret = mcp4728_write_input_reg(data, chan->channel);
+ break;
+ case IIO_CHAN_INFO_SCALE:
+ ret = -EINVAL;
+
+ for (gain = 0; gain < 2; ++gain) {
+ if (val == scale_avail[gain].integer &&
+ val2 == scale_avail[gain].micro) {
+
+ state->gain = gain;
+ ret = mcp4728_write_input_reg(data,
+ chan->channel);
+ }
+ }
+
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+ return ret;
+}
+
+static const struct iio_info mcp4728_info = {
+ .read_raw = mcp4728_read_raw,
+ .write_raw = mcp4728_write_raw,
+ .attrs = &mcp4728_attribute_group,
+ .driver_module = THIS_MODULE,
+};
+
+static int mcp4728_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct mcp4728_data *data;
+ struct iio_dev *indio_dev;
+ u8 inbuf[24];
+ u8 *reg;
+ u8 pd;
+ int err;
+ int i, gain;
+ u64 scale_uv;
+
+ indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+ if (indio_dev == NULL)
+ return -ENOMEM;
+ data = iio_priv(indio_dev);
+ i2c_set_clientdata(client, indio_dev);
+ data->client = client;
+
+ indio_dev->dev.parent = &client->dev;
+ indio_dev->info = &mcp4728_info;
+ indio_dev->channels = mcp4728_channels;
+ indio_dev->num_channels = MCP4728_NUM_CHANNELS;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+
+ /* read current DAC value */
+ err = i2c_master_recv(client, inbuf, 24);
+ if (err < 0) {
+ dev_err(&client->dev, "failed to read DAC value");
+ return err;
+ }
+
+ for (i = 0; i < MCP4728_NUM_CHANNELS; ++i) {
+ reg = &inbuf[6*i];
+ pd = (reg[1] >> 5) & 0x3;
+ data->channel_state[i].powerdown = pd > 0 ? true : false;
+
+ /* set to 500kohm_to_gnd if channel is now powered down */
+ data->channel_state[i].powerdown_mode = pd ? pd-1 : 2;
+ data->channel_state[i].dac_value = ((reg[1] & 0x0f) << 8) |
+ (reg[2]);
+ data->channel_state[i].gain = (reg[1] >> 4) & 0x01;
+
+ /* Use internal reference */
+ data->channel_state[i].vref = 1;
+
+ /* Populate available ADC input ranges */
+ for (gain = 0; gain < 2; gain++) {
+ /*
+ [gain=0] = Gain Setting 1, vref x 1
+ [gain=1] = Gain Setting 2, vref x 2
+
+ The scale is calculated by doing:
+ Vref >> (realbits - gain)
+ which multiplies by two on the second component
+ of the array.
+ */
+ scale_uv = ((u64) MCP4728_INT_VREF_MV * 100000) >>
+ (MCP4728_RESOLUTION - gain);
+ data->scale_avail[i][gain].micro =
+ do_div(scale_uv, 100000) * 10;
+ data->scale_avail[i][gain].integer = scale_uv;
+ }
+ }
+
+ return iio_device_register(indio_dev);
+}
+
+static int mcp4728_remove(struct i2c_client *client)
+{
+ iio_device_unregister(i2c_get_clientdata(client));
+ return 0;
+}
+
+static const struct i2c_device_id mcp4728_id[] = {
+ { "mcp4728", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, mcp4728_id);
+
+static struct i2c_driver mcp4728_driver = {
+ .driver = {
+ .name = MCP4728_DRV_NAME,
+ .pm = MCP4728_PM_OPS,
+ },
+ .probe = mcp4728_probe,
+ .remove = mcp4728_remove,
+ .id_table = mcp4728_id,
+};
+module_i2c_driver(mcp4728_driver);
+
+MODULE_AUTHOR("Evgeny Boger <boger@xxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("MCP4728 quad 12-bit DAC");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/iio/dac/mcp4728.h b/include/linux/iio/dac/mcp4728.h
new file mode 100644
index 0000000..14adb0c
--- /dev/null
+++ b/include/linux/iio/dac/mcp4728.h
@@ -0,0 +1,16 @@
+/*
+ * MCP4728 DAC driver
+ *
+ * Copyright (C) 2016 Evgeny Boger <boger@xxxxxxxxxxxxxx>
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#ifndef IIO_DAC_MCP4728_H_
+#define IIO_DAC_MCP4728_H_
+
+struct mcp4728_platform_data {
+ u16 vref_mv;
+};
+
+#endif /* IIO_DAC_MCP4728_H_ */
--
2.5.0
--
To unsubscribe from this list: send the line "unsubscribe linux-iio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
