Hello,
> This driver adds support for the Linear LTC26x6, LTC26x7 and LTC26x9 I2C
> DAC chips. The driver exposes as iio device. It provides interface to all
> channels of the DAC plus an additional channel (channel 15) which allows
> writing to all channels simultanously.
currently there is no way in IIO to express such "virtual" channels
> The scale factor is calculated based on the reference voltage. The
> reference voltage is set through a regulator in the device-tree.
link to datasheet would be nice
> Binding documentation is provided in ltc26xx.txt.
>
> Signed-off-by: Marc Andre <marc.andre@xxxxxxxxxx>
> ---
> .../devicetree/bindings/iio/dac/ltc26xx.txt | 50 +++
> drivers/iio/dac/Kconfig | 12 +
> drivers/iio/dac/Makefile | 1 +
> drivers/iio/dac/ltc26xx.c | 457 +++++++++++++++++++++
> 4 files changed, 520 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/iio/dac/ltc26xx.txt
> create mode 100644 drivers/iio/dac/ltc26xx.c
>
> diff --git a/Documentation/devicetree/bindings/iio/dac/ltc26xx.txt b/Documentation/devicetree/bindings/iio/dac/ltc26xx.txt
> new file mode 100644
> index 0000000..9b51aae
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/dac/ltc26xx.txt
> @@ -0,0 +1,50 @@
> +Driver for LTC2606, LTC2616, LTC2626, LTC2607, LTC2617, LTC2627,
> +LTC2609, LTC2619 and LTC2629 DAC with I2C interface
> +
> +Required properties:
> +- compatible: e.g. lltc,ltc2617
> +- reg: i2c address
> +
> +Required parameters for ltc26x6 and ltc26x7:
> +- vref-supply: Reference voltage supply
> +
> +Required parameters for ltc26x9:
> +- vref_a-supply: Reference voltage supply channel A
> +- vref_b-supply: Reference voltage supply channel B
> +- vref_c-supply: Reference voltage supply channel C
> +- vref_d-supply: Reference voltage supply channel D
> +
> +Available compatible strings. (defines the number of channels exposed)
> +lltc,ltc2606
> +lltc,ltc2616
> +lltc,ltc2626
> +lltc,ltc2607
> +lltc,ltc2617
> +lltc,ltc2627
> +lltc,ltc2609
> +lltc,ltc2619
> +lltc,ltc2629
> +
> +The driver registers a iio_device. The number of iio channels registered is
an iio_device
> +the number of channels available by the chip plus 1. The additional
> +channel (channel 15) can be used to write to all output simultanously.
outputs
it is not clear why channel 15 is the virtual channel; why 15?
MAX_CHANNEL is 4
is 15 an arbitraty number >= 4?
> +The scale parameter of channel 15 is always 0.
the value 1 might make more sense or no scale at all
> +
> +Example
> + i2c@7000c400 {
> + ltc2617: ltc2617@10 {
> + compatible = "lltc,ltc2617";
> + reg = <0x10>;
> + vref-supply = <&vdd_ltc_vref>;
> + };
> + };
> +
> + regulators {
> + vdd_ltc_vref: regulator@100 {
> + compatible = "regulator-fixed";
> + reg = <100>;
> + regulator-name = "LTC26xx VREF";
> + regulator-min-microvolt = <2500000>;
> + regulator-max-microvolt = <2500000>;
> + };
> + };
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index e701e28..aa3e637 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -142,6 +142,18 @@ config AD7303
> To compile this driver as module choose M here: the module will be called
> ad7303.
>
> +config LTC26xx
> + tristate "LTC26x6, LTC26x7 and LTC26x9 DAC driver"
> + depends on I2C
> + ---help---
> + Say Y here if you want to build a driver for the Linear
> + LTC2606, LTC2616, LTC2626, LTC2607, LTC2617, LTC2627,
> + LTC2609, LTC2619 or LTC2629 digital-to-analog converter (DAC)
> + with I2C interface
> +
> + To compile this driver as a module chose M here: the module
> + will be called ltc26xx
often we have a full stop (.) at the end :)
> +
> config M62332
> tristate "Mitsubishi M62332 DAC driver"
> depends on I2C
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index 63ae056..74bc8cc 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -16,6 +16,7 @@ obj-$(CONFIG_AD5764) += ad5764.o
> obj-$(CONFIG_AD5791) += ad5791.o
> obj-$(CONFIG_AD5686) += ad5686.o
> obj-$(CONFIG_AD7303) += ad7303.o
> +obj-$(CONFIG_LTC26xx) += ltc26xx.o
> obj-$(CONFIG_M62332) += m62332.o
> obj-$(CONFIG_MAX517) += max517.o
> obj-$(CONFIG_MAX5821) += max5821.o
> diff --git a/drivers/iio/dac/ltc26xx.c b/drivers/iio/dac/ltc26xx.c
> new file mode 100644
> index 0000000..4f9b381
> --- /dev/null
> +++ b/drivers/iio/dac/ltc26xx.c
> @@ -0,0 +1,457 @@
> +/*
> + * ltc26xx.c - Support for LTC26x6, LTC26x7 and LTC26x9 I2C DAC chips
> + *
> + * Copyright (C) 2015 Marc Andre <marc.andre@xxxxxxxxxx>
> + *
> + * 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.
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/slab.h>
> +#include <linux/jiffies.h>
> +#include <linux/i2c.h>
> +#include <linux/err.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +
> +#define LTC26xx_DRV_NAME "ltc26xx"
XX maybe?
> +
> +#define MAX_CHANNEL 4
LTC26XX_ prefix please
> +
> +/* Commands to LTC26xx */
> +#define COMMAND_WR 0x00 /* Write only */
> +#define COMMAND_UP 0x01 /* Update only */
> +#define COMMAND_WR_UP 0x03 /* Write & Update */
> +#define COMMAND_PD 0x04 /* Power Down */
LTC26XX_ prefix please
> +
> +static int ltc26xx_suspend(struct device *dev);
> +static int ltc26xx_resume(struct device *dev);
I don't think these forward decls are needed
> +
> +enum ltc26xx_device_ids {
> + ID_LTC2606,
> + ID_LTC2616,
> + ID_LTC2626,
> + ID_LTC2607,
> + ID_LTC2617,
> + ID_LTC2627,
> + ID_LTC2609,
> + ID_LTC2619,
> + ID_LTC2629
> +};
> +
> +struct ltc26xx_data {
> + struct i2c_client *client;
> + struct regulator *reg_vref[MAX_CHANNEL];
> + int channels;
> +};
> +
> +static long ltc26xx_get_scale_nv(struct ltc26xx_data *data,
> + int channel)
> +{
> + long long vref_nv;
> + long scale_nv;
> +
> + /* The generic channel 15 always returns 0 scale */
> + if (channel > MAX_CHANNEL)
should be >=?
> + return 0;
> +
> + if (data->reg_vref[channel]) {
> + vref_nv = regulator_get_voltage(data->reg_vref[channel]);
> + } else {
> + /* no regulator for the channel. This means we have a single
> + * reference supply.
> + */
> + vref_nv = regulator_get_voltage(data->reg_vref[0]);
> + }
> + vref_nv *= 1000;
> +
> + /* Corresponds to Vref / 2^(bits) */
> + scale_nv = vref_nv >> 16;
> +
> + return scale_nv;
> +}
> +
> +/*
this is not a proper kerneldoc comment
> + * channel: channel no or 0xf for all channels
> + * command: Command to LTC26xx
> + */
> +static int ltc26xx_set_value(struct iio_dev *indio_dev,
> + long val, int channel, int command)
> +{
> + struct ltc26xx_data *data = iio_priv(indio_dev);
> + struct i2c_client *client = data->client;
> + u8 outbuf[3];
> + int res;
> +
> + if (val < 0 || val >= 65536)
> + return -EINVAL;
> +
> + outbuf[0] = (channel & 0xf) | ((command & 0x0f) << 4);
> + outbuf[1] = (val >> 8) & 0xff;
> + outbuf[2] = (val & 0xff);
> +
> + res = i2c_master_send(client, outbuf, 3);
> + if (res < 0)
> + return res;
> + else if (res != 3)
> + return -EIO;
> + else
> + return 0;
> +}
> +
> +static int ltc26xx_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val,
> + int *val2,
> + long m)
> +{
> + struct ltc26xx_data *data = iio_priv(indio_dev);
> + unsigned long scale_nv;
> + int channel = chan->channel;
> +
> + switch (m) {
maybe support read on _RAW as well
> + case IIO_CHAN_INFO_SCALE:
> + scale_nv = ltc26xx_get_scale_nv(data, channel);
> + *val = scale_nv / 1000000000;
> + *val2 = scale_nv % 1000000000;
> + return IIO_VAL_INT_PLUS_NANO;
> + default:
> + break;
> + }
> + return -EINVAL;
> +}
> +
> +static int ltc26xx_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val, int val2, long mask)
> +{
> + int ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
check that val2 is 0
maybe do the validation of val here as well...
> + ret = ltc26xx_set_value(indio_dev, val, chan->channel,
> + COMMAND_WR_UP);
just return, drop ret temporary variable
> + break;
> + default:
> + ret = -EINVAL;
> + break;
> + }
> +
> + return ret;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int ltc26xx_suspend(struct device *dev)
> +{
> + u8 outbuf[3];
> + int ret;
> + int i;
> + struct i2c_client *client = to_i2c_client(dev);
> + struct iio_dev *indio_dev =
> + (struct iio_dev *)i2c_get_clientdata(client);
> + struct ltc26xx_data *data = iio_priv(indio_dev);
> +
> + outbuf[0] = (COMMAND_PD << 4) | 0xf; /* Suspend all channels */
> + outbuf[1] = 0;
> + outbuf[2] = 0;
> +
> + /* Send DAC into suspend */
> + ret = i2c_master_send(client, outbuf, 3);
> + if (ret != 3) {
> + dev_err(dev, "Error sending suspend i2c command: %d", ret);
> + goto exit;
> + }
> + ret = 0;
> +
> + /* Disable vref regulators */
> + for (i = 0; i < MAX_CHANNEL; i++) {
> + if (data->reg_vref[i]) {
> + ret = regulator_disable(data->reg_vref[i]);
> + if (ret) {
> + dev_err(dev,
> + "Error disabling regulator %d: %d",
> + i, ret);
> + goto exit;
> + }
> + }
> + }
> +
> +exit:
> + return ret;
> +}
> +
> +static int ltc26xx_resume(struct device *dev)
> +{
> + u8 outbuf[3];
> + int ret;
> + int i;
> + struct i2c_client *client = to_i2c_client(dev);
> + struct iio_dev *indio_dev =
> + (struct iio_dev *)i2c_get_clientdata(client);
> + struct ltc26xx_data *data = iio_priv(indio_dev);
> +
> + /* Enable all vref regulators */
> + for (i = 0; i < MAX_CHANNEL; i++) {
> + if (data->reg_vref[i]) {
> + ret = regulator_enable(data->reg_vref[i]);
> + if (ret) {
> + dev_err(dev,
> + "Error enabling regulator %d: %d",
> + i, ret);
> + goto exit;
> + }
> + }
> + }
> +
> + /* Resume DAC */
> + outbuf[0] = (COMMAND_UP << 4) | 0xf; /* Resume all channels */
> + outbuf[1] = 0;
> + outbuf[2] = 0;
> +
> + ret = i2c_master_send(to_i2c_client(dev), outbuf, 3);
> + if (ret != 3) {
> + dev_err(dev, "Error sending resume i2c command: %d", ret);
> + goto exit;
> + }
> + ret = 0;
> +
> +exit:
> + return ret;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(ltc26xx_pm_ops, ltc26xx_suspend, ltc26xx_resume);
> +#define LTC26xx_PM_OPS (<c26xx_pm_ops)
> +#else
> +#define LTC26xx_PM_OPS NULL
> +#endif
> +
> +static const struct iio_info ltc26xx_info = {
> + .read_raw = ltc26xx_read_raw,
> + .write_raw = ltc26xx_write_raw,
> + .driver_module = THIS_MODULE,
> +};
> +
> +#define LTC26xx_CHANNEL(chan) { \
> + .type = IIO_VOLTAGE, \
> + .indexed = 1, \
> + .output = 1, \
> + .channel = (chan), \
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> + BIT(IIO_CHAN_INFO_SCALE), \
> +}
> +
> +static const struct iio_chan_spec ltc26xx_channels[] = {
> + LTC26xx_CHANNEL(15), /* All channels simultanously */
> + LTC26xx_CHANNEL(0),
> + LTC26xx_CHANNEL(1),
> + LTC26xx_CHANNEL(2),
> + LTC26xx_CHANNEL(3),
> +};
> +
> +static int ltc26xx_get_regulators(struct i2c_client *client)
> +{
> + int err = 0;
> + int i;
> + struct regulator *reg;
> + struct iio_dev *indio_dev =
> + (struct iio_dev *)i2c_get_clientdata(client);
> + struct ltc26xx_data *data = iio_priv(indio_dev);
> +
> + for (i = 0; i < MAX_CHANNEL; i++)
> + data->reg_vref[i] = 0;
> +
> + /* LTC26x6 and LTCx7 have only one reference voltage */
> + if (data->channels == 1 || data->channels == 2) {
this could also go into a chip properties table
> + reg = devm_regulator_get(&client->dev, "vref");
lot of duplicate code (_get, _enable, log) here, put in a separate
function?
> + if (IS_ERR(reg)) {
> + dev_err(&client->dev,
> + "Can't get regulator vref: %ld\n",
> + PTR_ERR(reg));
> + err = PTR_ERR(reg);
> + goto exit_cleanup;
> + }
> +
> + err = regulator_enable(reg);
> + if (err < 0) {
> + dev_err(&client->dev,
> + "Error enabling regulator vref: %d\n",
> + err);
> + goto exit_cleanup;
> + }
> +
> + dev_info(&client->dev,
> + "Using voltage reference %duV",
> + regulator_get_voltage(reg));
> +
> + data->reg_vref[0] = reg;
> + }
> + /* LTC26x9 have 4 separate reference voltages */
> + else {
> + for (i = 0; i < 4; i++) {
> + char *name = "vref_a";
> +
> + name[5] = i + 'a';
efficielt, but a sprintf() might be clearer
> + reg = devm_regulator_get(&client->dev, name);
> + if (IS_ERR(reg)) {
> + dev_err(&client->dev,
> + "Can't get regulator %s: %ld\n",
> + name,
> + PTR_ERR(reg));
> + err = PTR_ERR(reg);
> + goto exit_cleanup;
> + }
> +
> + err = regulator_enable(reg);
> + if (err < 0) {
> + dev_err(&client->dev,
> + "Error enabling regulator %s: %d\n",
> + name,
> + err);
> + goto exit_cleanup;
> + }
> +
> + dev_info(&client->dev,
> + "Using voltage reference for %s: %duV",
> + name,
> + regulator_get_voltage(reg));
> +
> + data->reg_vref[i] = reg;
> + }
> + }
> +
> + return 0;
> +
> +exit_cleanup:
> + for (i = 0; i < MAX_CHANNEL; i++) {
> + if (data->reg_vref[i]) {
> + regulator_disable(data->reg_vref[i]);
> + devm_regulator_put(data->reg_vref[i]);
> + }
> + }
> + return err;
> +}
> +
> +static int ltc26xx_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct ltc26xx_data *data;
> + struct iio_dev *indio_dev;
> + int err;
> +
> + indio_dev = iio_device_alloc(sizeof(*data));
devm_iio_device_alloc()
> + if (!indio_dev) {
> + err = -ENOMEM;
just return?
> + goto exit;
> + }
> + data = iio_priv(indio_dev);
> + i2c_set_clientdata(client, indio_dev);
> + data->client = client;
> +
> + /* establish that the iio_dev is a child of the i2c device */
> + indio_dev->dev.parent = &client->dev;
> +
> + /* Define channel count based on DAC type */
please use a static const table to record chip properties and look up by
ID
> + if (id->driver_data == ID_LTC2606 ||
> + id->driver_data == ID_LTC2616 ||
> + id->driver_data == ID_LTC2626) {
> + indio_dev->num_channels = 2;
> + data->channels = 1;
> + } else if (id->driver_data == ID_LTC2607 ||
> + id->driver_data == ID_LTC2617 ||
> + id->driver_data == ID_LTC2627) {
> + indio_dev->num_channels = 3;
> + data->channels = 2;
> + } else {
> + indio_dev->num_channels = 5;
> + data->channels = 4;
> + }
> + indio_dev->channels = ltc26xx_channels;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->info = <c26xx_info;
> +
> + err = ltc26xx_get_regulators(client);
> + if (err) {
> + dev_err(&client->dev,
> + "Failed to initialized vref: %d. Aborting.",
drop "Aborting"
> + err);
> + goto exit_free_device;
> + }
> +
> + err = iio_device_register(indio_dev);
> + if (err) {
> + dev_err(&client->dev,
> + "Failed to register iio device: %d. Aborting.",
> + err);
> + goto exit_free_device;
> + }
> +
> + dev_info(&client->dev, "LTC26xx DAC registered\n");
> +
> + return 0;
> +
> +exit_free_device:
> + iio_device_free(indio_dev);
> +exit:
> + return err;
> +}
> +
> +static int ltc26xx_remove(struct i2c_client *client)
> +{
> + iio_device_unregister(i2c_get_clientdata(client));
> + iio_device_free(i2c_get_clientdata(client));
> +
> + dev_dbg(&client->dev, "LTC26xx DAC unregistered\n");
> +
> + return 0;
> +}
> +
> +static const struct i2c_device_id ltc26xx_id[] = {
> + { "ltc2606", ID_LTC2606 },
> + { "ltc2616", ID_LTC2616 },
> + { "ltc2626", ID_LTC2626 },
> + { "ltc2607", ID_LTC2607 },
> + { "ltc2617", ID_LTC2617 },
> + { "ltc2627", ID_LTC2627 },
> + { "ltc2609", ID_LTC2609 },
> + { "ltc2619", ID_LTC2619 },
> + { "ltc2629", ID_LTC2629 },
> + { }
> +};
> +MODULE_DEVICE_TABLE(i2c, ltc26xx_id);
> +
> +static const struct of_device_id ltc26xx_dt_ids[] = {
> + { .compatible = "lltc,ltc2606", .data = (void *)<c26xx_id[0] },
.data = ... is ugly, really needed?
> + { .compatible = "lltc,ltc2616", .data = (void *)<c26xx_id[1] },
> + { .compatible = "lltc,ltc2626", .data = (void *)<c26xx_id[2] },
> + { .compatible = "lltc,ltc2607", .data = (void *)<c26xx_id[3] },
> + { .compatible = "lltc,ltc2617", .data = (void *)<c26xx_id[4] },
> + { .compatible = "lltc,ltc2627", .data = (void *)<c26xx_id[5] },
> + { .compatible = "lltc,ltc2609", .data = (void *)<c26xx_id[6] },
> + { .compatible = "lltc,ltc2619", .data = (void *)<c26xx_id[7] },
> + { .compatible = "lltc,ltc2629", .data = (void *)<c26xx_id[8] },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, ltc26xx_dt_ids);
> +
> +static struct i2c_driver ltc26xx_driver = {
> + .driver = {
> + .name = LTC26xx_DRV_NAME,
> + .pm = LTC26xx_PM_OPS,
> + .of_match_table = of_match_ptr(ltc26xx_dt_ids),
> + },
> + .probe = ltc26xx_probe,
> + .remove = ltc26xx_remove,
> + .id_table = ltc26xx_id,
> +};
> +module_i2c_driver(ltc26xx_driver);
> +
> +MODULE_AUTHOR("Marc Andre <marc.andre@xxxxxxxxxx>");
> +MODULE_DESCRIPTION("LTC26x6, LTC26x7 and LTC26x9 DAC driver");
> +MODULE_LICENSE("GPL");
>
--
Peter Meerwald
+43-664-2444418 (mobile)
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