[PATCH v3 1/1] iio: adc: tlc4541: add support for TI tlc4541 adc

[PATCH v3 1/1] iio: adc: tlc4541: add support for TI tlc4541 adc

[Phil Reid]

This adds TI's tlc4541 16-bit ADC driver. Which is a single channel
ADC. Supports raw and trigger buffer access.
Also supports the tlc3541 14-bit device, which has not been tested.
Implementation of the tlc3541 is fairly straight forward thou.

Acked-by: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Signed-off-by: Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org>
---

Notes:
    Changes from v2:
    - Fix paste error in binding document.
    - Remove index from channel description. Note this break libiio.
      libiio will no longer recognise that the cahnnel is buffer enabled.
    - Add brackets to macro parameter bitshift
    - Make tcl3541 / tcl4541 order in code consistent.
    - Use spi_message_init_with_transfers
    - Cleanup whitespace lines
    - Add TLC3541 to kconfig description
    - Add Robs Ack.
    
    Changes from v1:
    - Add tlc3541 support and chan spec.
    - remove fields that where already 0 from TLC4541_V_CHAN macro
    - Increase rx_buf size in tlc4541_state to avoid copy in tlc4541_trigger_handle
    - Remove erroneous be16_to_cpu in tlc4541_trigger_handle
    - Docs/binding: spi -> SPI & add ti,tlc3541

 .../devicetree/bindings/iio/adc/ti-tlc4541.txt     |  17 ++
 drivers/iio/adc/Kconfig                            |  12 +
 drivers/iio/adc/Makefile                           |   1 +
 drivers/iio/adc/ti-tlc4541.c                       | 271 +++++++++++++++++++++
 4 files changed, 301 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/ti-tlc4541.txt
 create mode 100644 drivers/iio/adc/ti-tlc4541.c

diff --git a/Documentation/devicetree/bindings/iio/adc/ti-tlc4541.txt b/Documentation/devicetree/bindings/iio/adc/ti-tlc4541.txt
new file mode 100644
index 0000000..6b26927
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/ti-tlc4541.txt
@@ -0,0 +1,17 @@
+* Texas Instruments' TLC4541
+
+Required properties:
+ - compatible: Should be one of
+	* "ti,tlc4541"
+	* "ti,tlc3541"
+	- reg: SPI chip select number for the device
+ - vref-supply: The regulator supply for ADC reference voltage
+ - spi-max-frequency: Max SPI frequency to use (<= 200000)
+
+Example:
+adc@0 {
+	compatible = "ti,tlc4541";
+	reg = <0>;
+	vref-supply = <&vdd_supply>;
+	spi-max-frequency = <200000>;
+};
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 99c0514..fb9ede7 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -525,6 +525,18 @@ config TI_AM335X_ADC
 	  To compile this driver as a module, choose M here: the module will be
 	  called ti_am335x_adc.
 
+config TI_TLC4541
+	tristate "Texas Instruments TLC4541 ADC driver"
+	depends on SPI
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say yes here to build support for Texas Instruments TLC4541 / TLC3541
+	  ADC chips.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called ti-tlc4541.
+
 config TWL4030_MADC
 	tristate "TWL4030 MADC (Monitoring A/D Converter)"
 	depends on TWL4030_CORE
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 7a40c04..9bf2377 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -49,6 +49,7 @@ obj-$(CONFIG_TI_ADC161S626) += ti-adc161s626.o
 obj-$(CONFIG_TI_ADS1015) += ti-ads1015.o
 obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
 obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
+obj-$(CONFIG_TI_TLC4541) += ti-tlc4541.o
 obj-$(CONFIG_TWL4030_MADC) += twl4030-madc.o
 obj-$(CONFIG_TWL6030_GPADC) += twl6030-gpadc.o
 obj-$(CONFIG_VF610_ADC) += vf610_adc.o
diff --git a/drivers/iio/adc/ti-tlc4541.c b/drivers/iio/adc/ti-tlc4541.c
new file mode 100644
index 0000000..78d91a0
--- /dev/null
+++ b/drivers/iio/adc/ti-tlc4541.c
@@ -0,0 +1,271 @@
+/*
+ * TI tlc4541 ADC Driver
+ *
+ * Copyright (C) 2017 Phil Reid
+ *
+ * Datasheets can be found here:
+ * http://www.ti.com/lit/gpn/tlc3541
+ * http://www.ti.com/lit/gpn/tlc4541
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * The tlc4541 requires 24 clock cycles to start a transfer.
+ * Conversion then takes 2.94us to complete before data is ready
+ * Data is returned MSB first.
+ */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/sysfs.h>
+
+struct tlc4541_state {
+	struct spi_device               *spi;
+	struct regulator                *reg;
+	struct spi_transfer             scan_single_xfer[3];
+	struct spi_message              scan_single_msg;
+
+	/*
+	 * DMA (thus cache coherency maintenance) requires the
+	 * transfer buffers to live in their own cache lines.
+	 * 2 bytes data + 6 bytes padding + 8 bytes timestamp when
+	 * call iio_push_to_buffers_with_timestamp.
+	 */
+	__be16                          rx_buf[8] ____cacheline_aligned;
+};
+
+struct tlc4541_chip_info {
+	const struct iio_chan_spec *channels;
+	unsigned int num_channels;
+};
+
+enum tlc4541_id {
+	TLC3541,
+	TLC4541,
+};
+
+#define TLC4541_V_CHAN(bits, bitshift) {                              \
+		.type = IIO_VOLTAGE,                                  \
+		.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 = (bitshift),                          \
+			.endianness = IIO_BE,                         \
+		},                                                    \
+	}
+
+#define DECLARE_TLC4541_CHANNELS(name, bits, bitshift) \
+const struct iio_chan_spec name ## _channels[] = { \
+	TLC4541_V_CHAN(bits, bitshift), \
+	IIO_CHAN_SOFT_TIMESTAMP(1), \
+}
+
+static DECLARE_TLC4541_CHANNELS(tlc3541, 14, 2);
+static DECLARE_TLC4541_CHANNELS(tlc4541, 16, 0);
+
+static const struct tlc4541_chip_info tlc4541_chip_info[] = {
+	[TLC3541] = {
+		.channels = tlc3541_channels,
+		.num_channels = ARRAY_SIZE(tlc3541_channels),
+	},
+	[TLC4541] = {
+		.channels = tlc4541_channels,
+		.num_channels = ARRAY_SIZE(tlc4541_channels),
+	},
+};
+
+static irqreturn_t tlc4541_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct tlc4541_state *st = iio_priv(indio_dev);
+	int ret;
+
+	ret = spi_sync(st->spi, &st->scan_single_msg);
+	if (ret < 0)
+		goto done;
+
+	iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
+					   iio_get_time_ns(indio_dev));
+
+done:
+	iio_trigger_notify_done(indio_dev->trig);
+	return IRQ_HANDLED;
+}
+
+static int tlc4541_get_range(struct tlc4541_state *st)
+{
+	int vref;
+
+	vref = regulator_get_voltage(st->reg);
+	if (vref < 0)
+		return vref;
+
+	vref /= 1000;
+
+	return vref;
+}
+
+static int tlc4541_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val,
+			    int *val2,
+			    long m)
+{
+	int ret = 0;
+	struct tlc4541_state *st = iio_priv(indio_dev);
+
+	switch (m) {
+	case IIO_CHAN_INFO_RAW:
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
+		ret = spi_sync(st->spi, &st->scan_single_msg);
+		iio_device_release_direct_mode(indio_dev);
+		if (ret < 0)
+			return ret;
+		*val = be16_to_cpu(st->rx_buf[0]);
+		*val = *val >> chan->scan_type.shift;
+		*val &= GENMASK(chan->scan_type.realbits - 1, 0);
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		ret = tlc4541_get_range(st);
+		if (ret < 0)
+			return ret;
+		*val = ret;
+		*val2 = chan->scan_type.realbits;
+		return IIO_VAL_FRACTIONAL_LOG2;
+	}
+	return -EINVAL;
+}
+
+static const struct iio_info tlc4541_info = {
+	.read_raw = &tlc4541_read_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static int tlc4541_probe(struct spi_device *spi)
+{
+	struct tlc4541_state *st;
+	struct iio_dev *indio_dev;
+	const struct tlc4541_chip_info *info;
+	int ret;
+	int8_t device_init = 0;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+	if (indio_dev == NULL)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+
+	spi_set_drvdata(spi, indio_dev);
+
+	st->spi = spi;
+
+	info = &tlc4541_chip_info[spi_get_device_id(spi)->driver_data];
+
+	indio_dev->name = spi_get_device_id(spi)->name;
+	indio_dev->dev.parent = &spi->dev;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = info->channels;
+	indio_dev->num_channels = info->num_channels;
+	indio_dev->info = &tlc4541_info;
+
+	/* perform reset */
+	spi_write(spi, &device_init, 1);
+
+	/* Setup default message */
+	st->scan_single_xfer[0].rx_buf = &st->rx_buf[0];
+	st->scan_single_xfer[0].len = 3;
+	st->scan_single_xfer[1].delay_usecs = 3;
+	st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
+	st->scan_single_xfer[2].len = 2;
+
+	spi_message_init_with_transfers(&st->scan_single_msg,
+					st->scan_single_xfer, 3);
+
+	st->reg = devm_regulator_get(&spi->dev, "vref");
+	if (IS_ERR(st->reg))
+		return PTR_ERR(st->reg);
+
+	ret = regulator_enable(st->reg);
+	if (ret)
+		return ret;
+
+	ret = iio_triggered_buffer_setup(indio_dev, NULL,
+			&tlc4541_trigger_handler, NULL);
+	if (ret)
+		goto error_disable_reg;
+
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		goto error_cleanup_buffer;
+
+	return 0;
+
+error_cleanup_buffer:
+	iio_triggered_buffer_cleanup(indio_dev);
+error_disable_reg:
+	regulator_disable(st->reg);
+
+	return ret;
+}
+
+static int tlc4541_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct tlc4541_state *st = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+	iio_triggered_buffer_cleanup(indio_dev);
+	regulator_disable(st->reg);
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id tlc4541_dt_ids[] = {
+	{ .compatible = "ti,tlc3541", },
+	{ .compatible = "ti,tlc4541", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, tlc4541_dt_ids);
+#endif
+
+static const struct spi_device_id tlc4541_id[] = {
+	{"tlc3541", TLC3541},
+	{"tlc4541", TLC4541},
+	{}
+};
+MODULE_DEVICE_TABLE(spi, tlc4541_id);
+
+static struct spi_driver tlc4541_driver = {
+	.driver = {
+		.name   = "tlc4541",
+		.of_match_table = of_match_ptr(tlc4541_dt_ids),
+	},
+	.probe          = tlc4541_probe,
+	.remove         = tlc4541_remove,
+	.id_table       = tlc4541_id,
+};
+module_spi_driver(tlc4541_driver);
+
+MODULE_AUTHOR("Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org>");
+MODULE_DESCRIPTION("Texas Instruments TLC4541 ADC");
+MODULE_LICENSE("GPL v2");
-- 
1.8.3.1

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Re: [PATCH v3 1/1] iio: adc: tlc4541: add support for TI tlc4541 adc

[Jonathan Cameron]

On 16/01/17 08:38, Phil Reid wrote:
> This adds TI's tlc4541 16-bit ADC driver. Which is a single channel
> ADC. Supports raw and trigger buffer access.
> Also supports the tlc3541 14-bit device, which has not been tested.
> Implementation of the tlc3541 is fairly straight forward thou.
> 
> Acked-by: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> Signed-off-by: Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org>
Excellent.

Applied to the togreg branch of iio.git and initially pushed out
as testing for the autobuilders to play with it.

Thanks,

Jonathan
> ---
> 
> Notes:
>     Changes from v2:
>     - Fix paste error in binding document.
>     - Remove index from channel description. Note this break libiio.
>       libiio will no longer recognise that the cahnnel is buffer enabled.
>     - Add brackets to macro parameter bitshift
>     - Make tcl3541 / tcl4541 order in code consistent.
>     - Use spi_message_init_with_transfers
>     - Cleanup whitespace lines
>     - Add TLC3541 to kconfig description
>     - Add Robs Ack.
>     
>     Changes from v1:
>     - Add tlc3541 support and chan spec.
>     - remove fields that where already 0 from TLC4541_V_CHAN macro
>     - Increase rx_buf size in tlc4541_state to avoid copy in tlc4541_trigger_handle
>     - Remove erroneous be16_to_cpu in tlc4541_trigger_handle
>     - Docs/binding: spi -> SPI & add ti,tlc3541
> 
>  .../devicetree/bindings/iio/adc/ti-tlc4541.txt     |  17 ++
>  drivers/iio/adc/Kconfig                            |  12 +
>  drivers/iio/adc/Makefile                           |   1 +
>  drivers/iio/adc/ti-tlc4541.c                       | 271 +++++++++++++++++++++
>  4 files changed, 301 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/ti-tlc4541.txt
>  create mode 100644 drivers/iio/adc/ti-tlc4541.c
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/ti-tlc4541.txt b/Documentation/devicetree/bindings/iio/adc/ti-tlc4541.txt
> new file mode 100644
> index 0000000..6b26927
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/ti-tlc4541.txt
> @@ -0,0 +1,17 @@
> +* Texas Instruments' TLC4541
> +
> +Required properties:
> + - compatible: Should be one of
> +	* "ti,tlc4541"
> +	* "ti,tlc3541"
> +	- reg: SPI chip select number for the device
> + - vref-supply: The regulator supply for ADC reference voltage
> + - spi-max-frequency: Max SPI frequency to use (<= 200000)
> +
> +Example:
> +adc@0 {
> +	compatible = "ti,tlc4541";
> +	reg = <0>;
> +	vref-supply = <&vdd_supply>;
> +	spi-max-frequency = <200000>;
> +};
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 99c0514..fb9ede7 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -525,6 +525,18 @@ config TI_AM335X_ADC
>  	  To compile this driver as a module, choose M here: the module will be
>  	  called ti_am335x_adc.
>  
> +config TI_TLC4541
> +	tristate "Texas Instruments TLC4541 ADC driver"
> +	depends on SPI
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
> +	help
> +	  Say yes here to build support for Texas Instruments TLC4541 / TLC3541
> +	  ADC chips.
> +
> +	  This driver can also be built as a module. If so, the module will be
> +	  called ti-tlc4541.
> +
>  config TWL4030_MADC
>  	tristate "TWL4030 MADC (Monitoring A/D Converter)"
>  	depends on TWL4030_CORE
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 7a40c04..9bf2377 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -49,6 +49,7 @@ obj-$(CONFIG_TI_ADC161S626) += ti-adc161s626.o
>  obj-$(CONFIG_TI_ADS1015) += ti-ads1015.o
>  obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
>  obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
> +obj-$(CONFIG_TI_TLC4541) += ti-tlc4541.o
>  obj-$(CONFIG_TWL4030_MADC) += twl4030-madc.o
>  obj-$(CONFIG_TWL6030_GPADC) += twl6030-gpadc.o
>  obj-$(CONFIG_VF610_ADC) += vf610_adc.o
> diff --git a/drivers/iio/adc/ti-tlc4541.c b/drivers/iio/adc/ti-tlc4541.c
> new file mode 100644
> index 0000000..78d91a0
> --- /dev/null
> +++ b/drivers/iio/adc/ti-tlc4541.c
> @@ -0,0 +1,271 @@
> +/*
> + * TI tlc4541 ADC Driver
> + *
> + * Copyright (C) 2017 Phil Reid
> + *
> + * Datasheets can be found here:
> + * http://www.ti.com/lit/gpn/tlc3541
> + * http://www.ti.com/lit/gpn/tlc4541
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * The tlc4541 requires 24 clock cycles to start a transfer.
> + * Conversion then takes 2.94us to complete before data is ready
> + * Data is returned MSB first.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/interrupt.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/iio/triggered_buffer.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +#include <linux/spi/spi.h>
> +#include <linux/sysfs.h>
> +
> +struct tlc4541_state {
> +	struct spi_device               *spi;
> +	struct regulator                *reg;
> +	struct spi_transfer             scan_single_xfer[3];
> +	struct spi_message              scan_single_msg;
> +
> +	/*
> +	 * DMA (thus cache coherency maintenance) requires the
> +	 * transfer buffers to live in their own cache lines.
> +	 * 2 bytes data + 6 bytes padding + 8 bytes timestamp when
> +	 * call iio_push_to_buffers_with_timestamp.
> +	 */
> +	__be16                          rx_buf[8] ____cacheline_aligned;
> +};
> +
> +struct tlc4541_chip_info {
> +	const struct iio_chan_spec *channels;
> +	unsigned int num_channels;
> +};
> +
> +enum tlc4541_id {
> +	TLC3541,
> +	TLC4541,
> +};
> +
> +#define TLC4541_V_CHAN(bits, bitshift) {                              \
> +		.type = IIO_VOLTAGE,                                  \
> +		.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 = (bitshift),                          \
> +			.endianness = IIO_BE,                         \
> +		},                                                    \
> +	}
> +
> +#define DECLARE_TLC4541_CHANNELS(name, bits, bitshift) \
> +const struct iio_chan_spec name ## _channels[] = { \
> +	TLC4541_V_CHAN(bits, bitshift), \
> +	IIO_CHAN_SOFT_TIMESTAMP(1), \
> +}
> +
> +static DECLARE_TLC4541_CHANNELS(tlc3541, 14, 2);
> +static DECLARE_TLC4541_CHANNELS(tlc4541, 16, 0);
> +
> +static const struct tlc4541_chip_info tlc4541_chip_info[] = {
> +	[TLC3541] = {
> +		.channels = tlc3541_channels,
> +		.num_channels = ARRAY_SIZE(tlc3541_channels),
> +	},
> +	[TLC4541] = {
> +		.channels = tlc4541_channels,
> +		.num_channels = ARRAY_SIZE(tlc4541_channels),
> +	},
> +};
> +
> +static irqreturn_t tlc4541_trigger_handler(int irq, void *p)
> +{
> +	struct iio_poll_func *pf = p;
> +	struct iio_dev *indio_dev = pf->indio_dev;
> +	struct tlc4541_state *st = iio_priv(indio_dev);
> +	int ret;
> +
> +	ret = spi_sync(st->spi, &st->scan_single_msg);
> +	if (ret < 0)
> +		goto done;
> +
> +	iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
> +					   iio_get_time_ns(indio_dev));
> +
> +done:
> +	iio_trigger_notify_done(indio_dev->trig);
> +	return IRQ_HANDLED;
> +}
> +
> +static int tlc4541_get_range(struct tlc4541_state *st)
> +{
> +	int vref;
> +
> +	vref = regulator_get_voltage(st->reg);
> +	if (vref < 0)
> +		return vref;
> +
> +	vref /= 1000;
> +
> +	return vref;
> +}
> +
> +static int tlc4541_read_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int *val,
> +			    int *val2,
> +			    long m)
> +{
> +	int ret = 0;
> +	struct tlc4541_state *st = iio_priv(indio_dev);
> +
> +	switch (m) {
> +	case IIO_CHAN_INFO_RAW:
> +		ret = iio_device_claim_direct_mode(indio_dev);
> +		if (ret)
> +			return ret;
> +		ret = spi_sync(st->spi, &st->scan_single_msg);
> +		iio_device_release_direct_mode(indio_dev);
> +		if (ret < 0)
> +			return ret;
> +		*val = be16_to_cpu(st->rx_buf[0]);
> +		*val = *val >> chan->scan_type.shift;
> +		*val &= GENMASK(chan->scan_type.realbits - 1, 0);
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		ret = tlc4541_get_range(st);
> +		if (ret < 0)
> +			return ret;
> +		*val = ret;
> +		*val2 = chan->scan_type.realbits;
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +	}
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info tlc4541_info = {
> +	.read_raw = &tlc4541_read_raw,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +static int tlc4541_probe(struct spi_device *spi)
> +{
> +	struct tlc4541_state *st;
> +	struct iio_dev *indio_dev;
> +	const struct tlc4541_chip_info *info;
> +	int ret;
> +	int8_t device_init = 0;
> +
> +	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> +	if (indio_dev == NULL)
> +		return -ENOMEM;
> +
> +	st = iio_priv(indio_dev);
> +
> +	spi_set_drvdata(spi, indio_dev);
> +
> +	st->spi = spi;
> +
> +	info = &tlc4541_chip_info[spi_get_device_id(spi)->driver_data];
> +
> +	indio_dev->name = spi_get_device_id(spi)->name;
> +	indio_dev->dev.parent = &spi->dev;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = info->channels;
> +	indio_dev->num_channels = info->num_channels;
> +	indio_dev->info = &tlc4541_info;
> +
> +	/* perform reset */
> +	spi_write(spi, &device_init, 1);
> +
> +	/* Setup default message */
> +	st->scan_single_xfer[0].rx_buf = &st->rx_buf[0];
> +	st->scan_single_xfer[0].len = 3;
> +	st->scan_single_xfer[1].delay_usecs = 3;
> +	st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
> +	st->scan_single_xfer[2].len = 2;
> +
> +	spi_message_init_with_transfers(&st->scan_single_msg,
> +					st->scan_single_xfer, 3);
> +
> +	st->reg = devm_regulator_get(&spi->dev, "vref");
> +	if (IS_ERR(st->reg))
> +		return PTR_ERR(st->reg);
> +
> +	ret = regulator_enable(st->reg);
> +	if (ret)
> +		return ret;
> +
> +	ret = iio_triggered_buffer_setup(indio_dev, NULL,
> +			&tlc4541_trigger_handler, NULL);
> +	if (ret)
> +		goto error_disable_reg;
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret)
> +		goto error_cleanup_buffer;
> +
> +	return 0;
> +
> +error_cleanup_buffer:
> +	iio_triggered_buffer_cleanup(indio_dev);
> +error_disable_reg:
> +	regulator_disable(st->reg);
> +
> +	return ret;
> +}
> +
> +static int tlc4541_remove(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> +	struct tlc4541_state *st = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +	iio_triggered_buffer_cleanup(indio_dev);
> +	regulator_disable(st->reg);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id tlc4541_dt_ids[] = {
> +	{ .compatible = "ti,tlc3541", },
> +	{ .compatible = "ti,tlc4541", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, tlc4541_dt_ids);
> +#endif
> +
> +static const struct spi_device_id tlc4541_id[] = {
> +	{"tlc3541", TLC3541},
> +	{"tlc4541", TLC4541},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(spi, tlc4541_id);
> +
> +static struct spi_driver tlc4541_driver = {
> +	.driver = {
> +		.name   = "tlc4541",
> +		.of_match_table = of_match_ptr(tlc4541_dt_ids),
> +	},
> +	.probe          = tlc4541_probe,
> +	.remove         = tlc4541_remove,
> +	.id_table       = tlc4541_id,
> +};
> +module_spi_driver(tlc4541_driver);
> +
> +MODULE_AUTHOR("Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org>");
> +MODULE_DESCRIPTION("Texas Instruments TLC4541 ADC");
> +MODULE_LICENSE("GPL v2");
>