Hi On Sun, May 6, 2018 at 7:37 PM, Jonathan Cameron <jic23@xxxxxxxxxx> wrote: > On Sun, 6 May 2018 15:30:47 +0200 > Michael Trimarchi <michael@xxxxxxxxxxxxxxxxxxxx> wrote: > >> The following functions are supported: >> - write, read potentiometer value >> >> Value are exported in DBm because it's used as an audio >> attenuator > > This is interesting. The problem is that there is no way for > userspace to know that it is reporting in DBm rather than > reporting a linear gain or a straight forward resistance. > We have already drivers/iio/amplifiers/ad8366.c Each step is a db (negative) and last step is mapped to some type of mute (-90db) > This is rather closer in operation to the analog front end > driver I took the other day than to the other potentiometers > we have drivers for. > > Anyhow, how to solve this? Two options come to mind. > 1) Look up table mapping to linear gain as per current ABI > 2) Add a new channel type to represent the fact we are > looking at a logarithmic value, letting us handle it as DB. > > Lars, this area is probably more familiar to you than it is > to me, what do you think? > > Jonathan >> >> Datasheet: https://datasheets.maximintegrated.com/en/ds/DS1807.pdf >> >> Change-Id: I24f6b33cfa92ce16f489ff763f1df26126a1a7f2 > Please remember to drop these change IDs on patches to the mailing list > They don't mean anything to us unfortunately! > Yes sorry, I will drop it >> Signed-off-by: Michael Trimarchi <michael@xxxxxxxxxxxxxxxxxxxx> >> --- >> .../bindings/iio/potentiometer/ds1807.txt | 17 +++ >> drivers/iio/potentiometer/Kconfig | 10 ++ >> drivers/iio/potentiometer/Makefile | 1 + >> drivers/iio/potentiometer/ds1807.c | 156 +++++++++++++++++++++ >> 4 files changed, 184 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/iio/potentiometer/ds1807.txt >> create mode 100644 drivers/iio/potentiometer/ds1807.c >> >> diff --git a/Documentation/devicetree/bindings/iio/potentiometer/ds1807.txt b/Documentation/devicetree/bindings/iio/potentiometer/ds1807.txt >> new file mode 100644 >> index 0000000..3e30f4c >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/iio/potentiometer/ds1807.txt >> @@ -0,0 +1,17 @@ >> +* Maxim Integrated DS1807 digital potentiometer driver > > This might be a good candidate for the trivial-device.txt binding file. > No, it's not because I have in mind to support: * zero crossing * combined channel option using dts (means write them together) Michael >> + >> +The node for this driver must be a child node of a I2C controller, hence >> +all mandatory properties for your controller must be specified. See directory: >> + >> + Documentation/devicetree/bindings/i2c >> + >> +for more details. >> + >> +Required properties: >> + - compatible: "maxim,ds1807", >> + >> +Example: >> +ds1807: ds1807@1 { >> + reg = <0x28>; >> + compatible = "maxim,ds1807"; >> +}; >> diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig >> index 79ec2eb..92e5a6b 100644 >> --- a/drivers/iio/potentiometer/Kconfig >> +++ b/drivers/iio/potentiometer/Kconfig >> @@ -25,6 +25,16 @@ config DS1803 >> To compile this driver as a module, choose M here: the >> module will be called ds1803. >> >> +config DS1807 >> + tristate "Maxim Integrated DS1807 Digital Potentiometer driver" >> + depends on I2C >> + help >> + Say yes here to build support for the Maxim Integrated DS1807 >> + digital potentiometer chip. Value are reported back in DBm >> + >> + To compile this driver as a module, choose M here: the >> + module will be called ds1807. >> + >> config MAX5481 >> tristate "Maxim MAX5481-MAX5484 Digital Potentiometer driver" >> depends on SPI >> diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile >> index 4af6578..3c409bb 100644 >> --- a/drivers/iio/potentiometer/Makefile >> +++ b/drivers/iio/potentiometer/Makefile >> @@ -6,6 +6,7 @@ >> # When adding new entries keep the list in alphabetical order >> obj-$(CONFIG_AD5272) += ad5272.o >> obj-$(CONFIG_DS1803) += ds1803.o >> +obj-$(CONFIG_DS1807) += ds1807.o >> obj-$(CONFIG_MAX5481) += max5481.o >> obj-$(CONFIG_MAX5487) += max5487.o >> obj-$(CONFIG_MCP4018) += mcp4018.o >> diff --git a/drivers/iio/potentiometer/ds1807.c b/drivers/iio/potentiometer/ds1807.c >> new file mode 100644 >> index 0000000..acb4884 >> --- /dev/null >> +++ b/drivers/iio/potentiometer/ds1807.c >> @@ -0,0 +1,156 @@ >> +// SPDX-License-Identifier: GPL-2.0+ >> +/* >> + * Maxim Integrated DS1807 digital potentiometer driver >> + * Copyright (c) 2018 Michael Trimarchi >> + * >> + * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS1807.pdf >> + * >> + * DEVID #Wipers #Positions Resistor Opts (kOhm) i2c address >> + * ds1807 2 65 45 0101xxx >> + * >> + */ >> + >> +#include <linux/err.h> >> +#include <linux/export.h> >> +#include <linux/i2c.h> >> +#include <linux/iio/iio.h> >> +#include <linux/module.h> >> +#include <linux/of.h> >> + >> +#define DS1807_MAX_VALUE 64 >> +#define DS1807_MUTE -90 >> +#define DS1807_WRITE(chan) (0xa8 | ((chan) + 1)) >> + >> +#define DS1807_CHANNEL(ch) { \ >> + .type = IIO_CHAN_INFO_HARDWAREGAIN, \ >> + .indexed = 1, \ >> + .output = 1, \ >> + .channel = (ch), \ >> + .info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN), \ >> +} >> + >> +static const struct iio_chan_spec ds1807_channels[] = { >> + DS1807_CHANNEL(0), >> + DS1807_CHANNEL(1), >> +}; >> + >> +struct ds1807_data { >> + struct i2c_client *client; >> +}; >> + >> +static int ds1807_read_raw(struct iio_dev *indio_dev, >> + struct iio_chan_spec const *chan, >> + int *val, int *val2, long mask) >> +{ >> + struct ds1807_data *data = iio_priv(indio_dev); >> + int pot = chan->channel; >> + int ret; >> + u8 result[ARRAY_SIZE(ds1807_channels)]; >> + >> + switch (mask) { >> + case IIO_CHAN_INFO_HARDWAREGAIN: >> + ret = i2c_master_recv(data->client, result, >> + indio_dev->num_channels); >> + if (ret < 0) >> + return ret; >> + >> + *val2 = 0; >> + if (result[pot] == DS1807_MAX_VALUE) >> + *val = DS1807_MUTE; >> + else >> + *val = -result[pot]; >> + >> + return IIO_VAL_INT_PLUS_MICRO_DB; >> + } >> + >> + return -EINVAL; >> +} >> + >> +static int ds1807_write_raw(struct iio_dev *indio_dev, >> + struct iio_chan_spec const *chan, >> + int val, int val2, long mask) >> +{ >> + struct ds1807_data *data = iio_priv(indio_dev); >> + int pot = chan->channel; >> + >> + switch (mask) { >> + case IIO_CHAN_INFO_HARDWAREGAIN: >> + if (val2 != 0 || val < DS1807_MUTE || val > 0) >> + return -EINVAL; >> + break; >> + default: >> + return -EINVAL; >> + } >> + >> + val = (val == DS1807_MUTE) ? DS1807_MAX_VALUE : -val; >> + >> + return i2c_smbus_write_byte_data(data->client, DS1807_WRITE(pot), val); >> +} >> + >> +static const struct iio_info ds1807_info = { >> + .read_raw = ds1807_read_raw, >> + .write_raw = ds1807_write_raw, >> +}; >> + >> +static int ds1807_probe(struct i2c_client *client, >> + const struct i2c_device_id *id) >> +{ >> + struct device *dev = &client->dev; >> + struct ds1807_data *data; >> + struct iio_dev *indio_dev; >> + int channel, ret; >> + >> + indio_dev = devm_iio_device_alloc(dev, sizeof(*data)); >> + if (!indio_dev) >> + return -ENOMEM; >> + >> + i2c_set_clientdata(client, indio_dev); >> + >> + data = iio_priv(indio_dev); >> + data->client = client; >> + >> + indio_dev->dev.parent = dev; >> + indio_dev->info = &ds1807_info; >> + indio_dev->channels = ds1807_channels; >> + indio_dev->num_channels = ARRAY_SIZE(ds1807_channels); >> + indio_dev->name = client->name; >> + >> + /* reset device gain */ >> + for (channel = 0; channel < indio_dev->num_channels; channel++) { >> + ret = i2c_smbus_write_byte_data(client, DS1807_WRITE(channel), >> + DS1807_MUTE); >> + if (ret < 0) >> + return -ENODEV; >> + } >> + >> + return devm_iio_device_register(dev, indio_dev); >> +} >> + >> +#if defined(CONFIG_OF) >> +static const struct of_device_id ds1807_dt_ids[] = { >> + { .compatible = "maxim,ds1807", }, >> + {} >> +}; >> +MODULE_DEVICE_TABLE(of, ds1807_dt_ids); >> +#endif /* CONFIG_OF */ >> + >> +static const struct i2c_device_id ds1807_id[] = { >> + { "ds1807", }, >> + {} >> +}; >> +MODULE_DEVICE_TABLE(i2c, ds1807_id); >> + >> +static struct i2c_driver ds1807_driver = { >> + .driver = { >> + .name = "ds1807", >> + .of_match_table = of_match_ptr(ds1807_dt_ids), >> + }, >> + .probe = ds1807_probe, >> + .id_table = ds1807_id, >> +}; >> + >> +module_i2c_driver(ds1807_driver); >> + >> +MODULE_AUTHOR("Michael Trimarchi <michael@xxxxxxxxxxxxxxxxxxxx>"); >> +MODULE_DESCRIPTION("DS1807 digital potentiometer"); >> +MODULE_LICENSE("GPL v2"); > -- | Michael Nazzareno Trimarchi Amarula Solutions BV | | COO - Founder Cruquiuskade 47 | | +31(0)851119172 Amsterdam 1018 AM NL | | [`as] http://www.amarulasolutions.com | -- 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
