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Date: Sat, 21 Jun 2014 11:53:05 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Michael Welling <mwelling@...e.org>,
Lars-Peter Clausen <lars@...afoo.de>,
Peter Meerwald <pmeerw@...erw.net>, linux-iio@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5] iio: dac: mcp4902/mcp4912/mcp4922 dac driver
On 15/06/14 22:17, Michael Welling wrote:
> This patch provides an iio device driver for the Microchip
> MCP49x2 series DACs.
>
Normally this lot goes below the --- inorder that it doesn't then lead
to really long commit messages in git. Anyhow, I just dropped this stuff
during the commit. It's enough to have it in the list archives.
> v5:
> - Removes wildcard naming in filename and variables.
> - Switches to using iio_device_register/unregister to avoid race condition.
> - Removes --- around help in the Kconfig entry.
> - Removes unused variable.
> - Adds checking for val2 in write_raw function.
>
> v4:
> - Removes use of old IIO_ST macro.
> - Moves mosi variable to the state struct.
> - Removes default vref of 2.5v.
>
> v3:
> - Removes MCP49X2_RES_MASK and uses GENMASK directly.
> - Switch from using address to channel in functions.
>
> v2:
> - Switched to using GENMASK instead of creating a mask directly.
> - Switched from using address to channel.
> - Removed unnecessary feilds from channel macro.
> - Made SPI buffer cachline aligned.
> - Removed some uncessary bounds checking.
> - Report -EINVAL when writing a value beyond the range to DAC.
> - Switched to devm_iio_device_alloc.
> - Created a constant for the number of channels.
> - Switched to devm_ioo_device_register.
>
> Signed-off-by: Michael Welling <mwelling@...e.org>
Applied to the togreg branch of iio.git. Note this is initially pushed
out as testing to allow the autobuilders to do there work before I commit
to not rebasing the tree!
Thanks for your hard work on this. It's a nice little driver!
Jonathan
> ---
> drivers/iio/dac/Kconfig | 10 +++
> drivers/iio/dac/Makefile | 1 +
> drivers/iio/dac/mcp4922.c | 216 +++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 227 insertions(+)
> create mode 100644 drivers/iio/dac/mcp4922.c
>
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index f378ca8..f278eff 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -163,4 +163,14 @@ config MCP4725
> To compile this driver as a module, choose M here: the module
> will be called mcp4725.
>
> +config MCP4922
> + tristate "MCP4902, MCP4912, MCP4922 DAC driver"
> + depends on SPI
> + help
> + Say yes here to build the driver for the Microchip MCP4902
> + MCP4912, and MCP4922 DAC devices.
> +
> + To compile this driver as a module, choose M here: the module
> + will be called mcp4922.
> +
> endmenu
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index bb84ad6..1010764 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -18,3 +18,4 @@ obj-$(CONFIG_AD5686) += ad5686.o
> obj-$(CONFIG_AD7303) += ad7303.o
> obj-$(CONFIG_MAX517) += max517.o
> obj-$(CONFIG_MCP4725) += mcp4725.o
> +obj-$(CONFIG_MCP4922) += mcp4922.o
> diff --git a/drivers/iio/dac/mcp4922.c b/drivers/iio/dac/mcp4922.c
> new file mode 100644
> index 0000000..92cf4ca
> --- /dev/null
> +++ b/drivers/iio/dac/mcp4922.c
> @@ -0,0 +1,216 @@
> +/*
> + * mcp4922.c
> + *
> + * Driver for Microchip Digital to Analog Converters.
> + * Supports MCP4902, MCP4912, and MCP4922.
> + *
> + * Copyright (c) 2014 EMAC Inc.
> + *
> + * 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.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/spi/spi.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/bitops.h>
> +
> +#define MCP4922_NUM_CHANNELS 2
> +
> +enum mcp4922_supported_device_ids {
> + ID_MCP4902,
> + ID_MCP4912,
> + ID_MCP4922,
> +};
> +
> +struct mcp4922_state {
> + struct spi_device *spi;
> + unsigned int value[MCP4922_NUM_CHANNELS];
> + unsigned int vref_mv;
> + struct regulator *vref_reg;
> + u8 mosi[2] ____cacheline_aligned;
> +};
> +
> +#define MCP4922_CHAN(chan, bits) { \
> + .type = IIO_VOLTAGE, \
> + .output = 1, \
> + .indexed = 1, \
> + .channel = chan, \
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> + .scan_type = { \
> + .sign = 'u', \
> + .realbits = (bits), \
> + .storagebits = 16, \
> + .shift = 12 - (bits), \
> + }, \
> +}
> +
> +static int mcp4922_spi_write(struct mcp4922_state *state, u8 addr, u32 val)
> +{
> + state->mosi[1] = val & 0xff;
> + state->mosi[0] = (addr == 0) ? 0x00 : 0x80;
> + state->mosi[0] |= 0x30 | ((val >> 8) & 0x0f);
> +
> + return spi_write(state->spi, state->mosi, 2);
> +}
> +
> +static int mcp4922_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val,
> + int *val2,
> + long mask)
> +{
> + struct mcp4922_state *state = iio_priv(indio_dev);
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + *val = state->value[chan->channel];
> + return IIO_VAL_INT;
> + case IIO_CHAN_INFO_SCALE:
> + *val = state->vref_mv;
> + *val2 = chan->scan_type.realbits;
> + return IIO_VAL_FRACTIONAL_LOG2;
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static int mcp4922_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val,
> + int val2,
> + long mask)
> +{
> + struct mcp4922_state *state = iio_priv(indio_dev);
> +
> + if (val2 != 0)
> + return -EINVAL;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + if (val > GENMASK(chan->scan_type.realbits-1, 0))
> + return -EINVAL;
> + val <<= chan->scan_type.shift;
> + state->value[chan->channel] = val;
> + return mcp4922_spi_write(state, chan->channel, val);
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static const struct iio_chan_spec mcp4922_channels[3][MCP4922_NUM_CHANNELS] = {
> + [ID_MCP4902] = { MCP4922_CHAN(0, 8), MCP4922_CHAN(1, 8) },
> + [ID_MCP4912] = { MCP4922_CHAN(0, 10), MCP4922_CHAN(1, 10) },
> + [ID_MCP4922] = { MCP4922_CHAN(0, 12), MCP4922_CHAN(1, 12) },
> +};
> +
> +static const struct iio_info mcp4922_info = {
> + .read_raw = &mcp4922_read_raw,
> + .write_raw = &mcp4922_write_raw,
> + .driver_module = THIS_MODULE,
> +};
> +
> +static int mcp4922_probe(struct spi_device *spi)
> +{
> + struct iio_dev *indio_dev;
> + struct mcp4922_state *state;
> + const struct spi_device_id *id;
> + int ret;
> +
> + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
> + if (indio_dev == NULL)
> + return -ENOMEM;
> +
> + state = iio_priv(indio_dev);
> + state->spi = spi;
> + state->vref_reg = devm_regulator_get(&spi->dev, "vref");
> + if (IS_ERR(state->vref_reg)) {
> + dev_err(&spi->dev, "Vref regulator not specified\n");
> + return PTR_ERR(state->vref_reg);
> + }
> +
> + ret = regulator_enable(state->vref_reg);
> + if (ret) {
> + dev_err(&spi->dev, "Failed to enable vref regulator: %d\n",
> + ret);
> + return ret;
> + }
> +
> + ret = regulator_get_voltage(state->vref_reg);
> + if (ret < 0) {
> + dev_err(&spi->dev, "Failed to read vref regulator: %d\n",
> + ret);
> + goto error_disable_reg;
> + }
> + state->vref_mv = ret / 1000;
> +
> + spi_set_drvdata(spi, indio_dev);
> + id = spi_get_device_id(spi);
> + indio_dev->dev.parent = &spi->dev;
> + indio_dev->info = &mcp4922_info;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->channels = mcp4922_channels[id->driver_data];
> + indio_dev->num_channels = MCP4922_NUM_CHANNELS;
> + indio_dev->name = id->name;
> +
> + ret = iio_device_register(indio_dev);
> + if (ret) {
> + dev_err(&spi->dev, "Failed to register iio device: %d\n",
> + ret);
> + goto error_disable_reg;
> + }
> +
> + return 0;
> +
> +error_disable_reg:
> + regulator_disable(state->vref_reg);
> +
> + return ret;
> +}
> +
> +static int mcp4922_remove(struct spi_device *spi)
> +{
> + struct iio_dev *indio_dev = spi_get_drvdata(spi);
> + struct mcp4922_state *state;
> +
> + iio_device_unregister(indio_dev);
> + state = iio_priv(indio_dev);
> + regulator_disable(state->vref_reg);
> +
> + return 0;
> +}
> +
> +static const struct spi_device_id mcp4922_id[] = {
> + {"mcp4902", ID_MCP4902},
> + {"mcp4912", ID_MCP4912},
> + {"mcp4922", ID_MCP4922},
> + {}
> +};
> +MODULE_DEVICE_TABLE(spi, mcp4922_id);
> +
> +static struct spi_driver mcp4922_driver = {
> + .driver = {
> + .name = "mcp4922",
> + .owner = THIS_MODULE,
> + },
> + .probe = mcp4922_probe,
> + .remove = mcp4922_remove,
> + .id_table = mcp4922_id,
> +};
> +module_spi_driver(mcp4922_driver);
> +
> +MODULE_AUTHOR("Michael Welling <mwelling@...e.org>");
> +MODULE_DESCRIPTION("Microchip MCP4902, MCP4912, MCP4922 DAC");
> +MODULE_LICENSE("GPL v2");
>
--
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