[PATCH 1/2] dt-bindings: iio: dac: ti-dac082s085: Document new driver

[PATCH 1/2] dt-bindings: iio: dac: ti-dac082s085: Document new driver

[Lukas Wunner]

Add device tree bindings for Texas Instruments 8/10/12-bit 2/4-channel
DAC driver.

Cc: Mathias Duckeck <m.duckeck-XB/JSsFECOqzQB+pC5nmwQ@public.gmane.org>
Signed-off-by: Lukas Wunner <lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org>
---
 .../devicetree/bindings/iio/dac/ti-dac082s085.txt  | 34 ++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/dac/ti-dac082s085.txt

diff --git a/Documentation/devicetree/bindings/iio/dac/ti-dac082s085.txt b/Documentation/devicetree/bindings/iio/dac/ti-dac082s085.txt
new file mode 100644
index 000000000000..9cb0e10df704
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/dac/ti-dac082s085.txt
@@ -0,0 +1,34 @@
+Texas Instruments 8/10/12-bit 2/4-channel DAC driver
+
+Required properties:
+ - compatible:		Must be one of:
+			"ti,dac082s085"
+			"ti,dac102s085"
+			"ti,dac122s085"
+			"ti,dac084s085"
+			"ti,dac104s085"
+			"ti,dac124s085"
+ - reg: 		Chip select number.
+ - spi-cpha, spi-cpol:	SPI mode (0,1) or (1,0) must be used, so specify
+			either spi-cpha or spi-cpol (but not both).
+ - vref-supply: 	Phandle to the external reference voltage supply.
+
+For other required and optional properties of SPI slave nodes please refer to
+../../spi/spi-bus.txt.
+
+Example:
+	vref_2v5_reg: regulator-vref {
+		compatible = "regulator-fixed";
+		regulator-name = "2v5";
+		regulator-min-microvolt = <2500000>;
+		regulator-max-microvolt = <2500000>;
+		regulator-always-on;
+	};
+
+	dac@0 {
+		compatible = "ti,dac082s085";
+		reg = <0>;
+		spi-max-frequency = <40000000>;
+		spi-cpol;
+		vref-supply = <&vref_2v5_reg>;
+	};
-- 
2.11.0

[PATCH 2/2] iio: dac: Add Texas Instruments 8/10/12-bit 2/4-channel DAC driver

[Lukas Wunner]

The DACrrcS085 (rr = 08/10/12, c = 2/4) family of SPI DACs was
inherited by TI when they acquired National Semiconductor in 2011.
This driver was developed for and tested with the DAC082S085 built into
the Revolution Pi by KUNBUS, but should work with any of the other
chips as they share the same programming interface.

There is also a family of I2C DACs with just a single channel called
DACrr1C08x (rr = 08/10/12, x = 1/5).  Their programming interface is
very similar and it should be possible to extend the driver for these
chips with moderate effort.  Alternatively they could be integrated into
ad5446.c.  (The AD5301/AD5311/AD5321 use different power-down modes but
otherwise appear to be comparable.)

Furthermore there is a family of 8-channel DACs called DACrr8S085
(rr = 08/10/12) as well as two 16-bit DACs called DAC161Sxxx
(xxx = 055/997).  These are more complicated devices with support for
daisy-chaining and the ability to power down each channel separately.
They could either be handled by a separate driver or integrated into the
present driver with a larger effort.

Cc: Mathias Duckeck <m.duckeck-XB/JSsFECOqzQB+pC5nmwQ@public.gmane.org>
Signed-off-by: Lukas Wunner <lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org>
---
 Documentation/ABI/testing/sysfs-bus-iio |   1 +
 drivers/iio/dac/Kconfig                 |  10 +
 drivers/iio/dac/Makefile                |   1 +
 drivers/iio/dac/ti-dac082s085.c         | 347 ++++++++++++++++++++++++++++++++
 4 files changed, 359 insertions(+)
 create mode 100644 drivers/iio/dac/ti-dac082s085.c

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index 7eead5f97e02..407e4d1024ee 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -522,6 +522,7 @@ Description:
 		Specifies the output powerdown mode.
 		DAC output stage is disconnected from the amplifier and
 		1kohm_to_gnd: connected to ground via an 1kOhm resistor,
+		2.5kohm_to_gnd: connected to ground via a 2.5kOhm resistor,
 		6kohm_to_gnd: connected to ground via a 6kOhm resistor,
 		20kohm_to_gnd: connected to ground via a 20kOhm resistor,
 		90kohm_to_gnd: connected to ground via a 90kOhm resistor,
diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 25bed2d7d2b9..716fcb1610dd 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -300,6 +300,16 @@ config STM32_DAC
 config STM32_DAC_CORE
 	tristate
 
+config TI_DAC082S085
+	tristate "Texas Instruments 8/10/12-bit 2/4-channel DAC driver"
+	depends on SPI_MASTER
+	help
+	  Driver for the Texas Instruments (formerly National Semiconductor)
+	  DAC082S085, DAC102S085, DAC122S085, DAC084S085, DAC104S085 and
+	  DAC124S085.
+
+	  If compiled as a module, it will be called ti-dac082s085.
+
 config VF610_DAC
 	tristate "Vybrid vf610 DAC driver"
 	depends on OF
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index 603587cc2f07..1a2dd507b4d8 100644
--- a/drivers/iio/dac/Makefile
+++ b/drivers/iio/dac/Makefile
@@ -32,4 +32,5 @@ obj-$(CONFIG_MCP4725) += mcp4725.o
 obj-$(CONFIG_MCP4922) += mcp4922.o
 obj-$(CONFIG_STM32_DAC_CORE) += stm32-dac-core.o
 obj-$(CONFIG_STM32_DAC) += stm32-dac.o
+obj-$(CONFIG_TI_DAC082S085) += ti-dac082s085.o
 obj-$(CONFIG_VF610_DAC) += vf610_dac.o
diff --git a/drivers/iio/dac/ti-dac082s085.c b/drivers/iio/dac/ti-dac082s085.c
new file mode 100644
index 000000000000..22fdce512a09
--- /dev/null
+++ b/drivers/iio/dac/ti-dac082s085.c
@@ -0,0 +1,347 @@
+/*
+ * ti-dac082s085.c - Texas Instruments 8/10/12-bit 2/4-channel DAC driver
+ *
+ * Copyright (C) 2017 KUNBUS GmbH
+ *
+ * http://www.ti.com/lit/ds/symlink/dac082s085.pdf
+ * http://www.ti.com/lit/ds/symlink/dac102s085.pdf
+ * http://www.ti.com/lit/ds/symlink/dac122s085.pdf
+ * http://www.ti.com/lit/ds/symlink/dac084s085.pdf
+ * http://www.ti.com/lit/ds/symlink/dac104s085.pdf
+ * http://www.ti.com/lit/ds/symlink/dac124s085.pdf
+ *
+ * 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.
+ */
+
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+/**
+ * struct ti_dac_chip - TI DAC chip
+ * @lock: protects write sequences
+ * @vref: regulator generating Vref
+ * @mesg: SPI message to perform a write
+ * @xfer: SPI transfer used by @mesg
+ * @buf: buffer for @xfer
+ * @val: cached value of each output
+ * @powerdown: whether the chip is powered down
+ * @powerdown_mode: selected by the user
+ * @resolution: resolution of the chip
+ */
+struct ti_dac_chip {
+	struct mutex lock;
+	struct regulator *vref;
+	struct spi_message mesg;
+	struct spi_transfer xfer;
+	u8 buf[2] ____cacheline_aligned;
+	u16 val[4];
+	bool powerdown;
+	u8 powerdown_mode;
+	u8 resolution;
+};
+
+#define WRITE_NOT_UPDATE(chan)	(0x00 | (chan) << 6)
+#define WRITE_AND_UPDATE(chan)	(0x10 | (chan) << 6)
+#define WRITE_ALL_UPDATE	 0x20
+#define POWERDOWN(mode) 	(0x30 | ((mode) + 1) << 6)
+
+static int ti_dac_cmd(struct ti_dac_chip *ti_dac, u8 cmd, u16 val)
+{
+	u8 shift = 12 - ti_dac->resolution;
+
+	ti_dac->buf[0] = cmd | (val >> (8 - shift));
+	ti_dac->buf[1] = (val << shift) & 0xff;
+	return spi_sync(ti_dac->mesg.spi, &ti_dac->mesg);
+}
+
+static const char * const ti_dac_powerdown_modes[] = {
+	"2.5kohm_to_gnd", "100kohm_to_gnd", "three_state",
+};
+
+static int ti_dac_get_powerdown_mode(struct iio_dev *indio_dev,
+				     const struct iio_chan_spec *chan)
+{
+	struct ti_dac_chip *ti_dac = iio_priv(indio_dev);
+
+	return ti_dac->powerdown_mode;
+}
+
+static int ti_dac_set_powerdown_mode(struct iio_dev *indio_dev,
+				     const struct iio_chan_spec *chan,
+				     unsigned int mode)
+{
+	struct ti_dac_chip *ti_dac = iio_priv(indio_dev);
+	int ret;
+
+	if (ti_dac->powerdown_mode == mode)
+		return 0;
+
+	mutex_lock(&ti_dac->lock);
+	if (ti_dac->powerdown) {
+		ret = ti_dac_cmd(ti_dac, POWERDOWN(mode), 0);
+		if (ret) {
+			mutex_unlock(&ti_dac->lock);
+			return ret;
+		}
+	}
+	ti_dac->powerdown_mode = mode;
+	mutex_unlock(&ti_dac->lock);
+	return 0;
+}
+
+static const struct iio_enum ti_dac_powerdown_mode = {
+	.items = ti_dac_powerdown_modes,
+	.num_items = ARRAY_SIZE(ti_dac_powerdown_modes),
+	.get = ti_dac_get_powerdown_mode,
+	.set = ti_dac_set_powerdown_mode,
+};
+
+static ssize_t ti_dac_read_powerdown(struct iio_dev *indio_dev,
+				     uintptr_t private,
+				     const struct iio_chan_spec *chan,
+				     char *buf)
+{
+	struct ti_dac_chip *ti_dac = iio_priv(indio_dev);
+
+	return sprintf(buf, "%d\n", ti_dac->powerdown);
+}
+
+static ssize_t ti_dac_write_powerdown(struct iio_dev *indio_dev,
+				      uintptr_t private,
+				      const struct iio_chan_spec *chan,
+				      const char *buf, size_t len)
+{
+	struct ti_dac_chip *ti_dac = iio_priv(indio_dev);
+	bool powerdown;
+	int ret;
+
+	ret = strtobool(buf, &powerdown);
+	if (ret)
+		return ret;
+
+	if (ti_dac->powerdown == powerdown)
+		return len;
+
+	mutex_lock(&ti_dac->lock);
+	if (powerdown)
+		ret = ti_dac_cmd(ti_dac, POWERDOWN(ti_dac->powerdown_mode), 0);
+	else
+		ret = ti_dac_cmd(ti_dac, WRITE_AND_UPDATE(0), ti_dac->val[0]);
+	if (!ret)
+		ti_dac->powerdown = powerdown;
+	mutex_unlock(&ti_dac->lock);
+
+	return ret ? ret : len;
+}
+
+static const struct iio_chan_spec_ext_info ti_dac_ext_info[] = {
+	{
+		.name	   = "powerdown",
+		.read	   = ti_dac_read_powerdown,
+		.write	   = ti_dac_write_powerdown,
+		.shared	   = IIO_SHARED_BY_TYPE,
+	},
+	IIO_ENUM("powerdown_mode", IIO_SHARED_BY_TYPE, &ti_dac_powerdown_mode),
+	IIO_ENUM_AVAILABLE("powerdown_mode", &ti_dac_powerdown_mode),
+	{ },
+};
+
+#define TI_DAC_CHANNEL(chan) {					\
+	.type = IIO_VOLTAGE,					\
+	.channel = (chan),					\
+	.address = (chan),					\
+	.indexed = true,					\
+	.output = true,						\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+	.ext_info = ti_dac_ext_info,				\
+}
+
+static const struct iio_chan_spec ti_dac_channels[] = {
+	TI_DAC_CHANNEL(0),
+	TI_DAC_CHANNEL(1),
+	TI_DAC_CHANNEL(2),
+	TI_DAC_CHANNEL(3),
+};
+
+static int ti_dac_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2, long mask)
+{
+	struct ti_dac_chip *ti_dac = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		*val = ti_dac->val[chan->channel];
+		ret = IIO_VAL_INT;
+		break;
+
+	case IIO_CHAN_INFO_SCALE:
+		ret = regulator_get_voltage(ti_dac->vref);
+		if (ret < 0)
+			return ret;
+
+		*val = ret / 1000;
+		*val2 = ti_dac->resolution;
+		ret = IIO_VAL_FRACTIONAL_LOG2;
+		break;
+
+	default:
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+static int ti_dac_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int val, int val2, long mask)
+{
+	struct ti_dac_chip *ti_dac = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (ti_dac->val[chan->channel] == val)
+			return 0;
+
+		if (val >= (1 << ti_dac->resolution) || val < 0)
+			return -EINVAL;
+
+		if (ti_dac->powerdown)
+			return -EHOSTDOWN;
+
+		mutex_lock(&ti_dac->lock);
+		ret = ti_dac_cmd(ti_dac, WRITE_AND_UPDATE(chan->channel), val);
+		if (!ret)
+			ti_dac->val[chan->channel] = val;
+		mutex_unlock(&ti_dac->lock);
+		break;
+
+	default:
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+static int ti_dac_write_raw_get_fmt(struct iio_dev *indio_dev,
+				    struct iio_chan_spec const *chan, long mask)
+{
+	return IIO_VAL_INT;
+}
+
+static const struct iio_info ti_dac_info = {
+	.read_raw	   = ti_dac_read_raw,
+	.write_raw	   = ti_dac_write_raw,
+	.write_raw_get_fmt = ti_dac_write_raw_get_fmt,
+};
+
+static int ti_dac_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct ti_dac_chip *ti_dac;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*ti_dac));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	indio_dev->dev.parent = dev;
+	indio_dev->info = &ti_dac_info;
+	indio_dev->name = spi->modalias;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = ti_dac_channels;
+	spi_set_drvdata(spi, indio_dev);
+
+	ti_dac = iio_priv(indio_dev);
+	ti_dac->xfer.tx_buf = &ti_dac->buf;
+	ti_dac->xfer.len = sizeof(ti_dac->buf);
+	spi_message_init_with_transfers(&ti_dac->mesg, &ti_dac->xfer, 1);
+	ti_dac->mesg.spi = spi;
+
+	ret = sscanf(spi->modalias, "dac%2hhu%1d",
+		     &ti_dac->resolution, &indio_dev->num_channels);
+	WARN_ON(ret != 2);
+
+	ret = ti_dac_cmd(ti_dac, WRITE_ALL_UPDATE, 0);
+	if (ret) {
+		dev_err(dev, "failed to initialize outputs to 0\n");
+		return ret;
+	}
+
+	ti_dac->vref = devm_regulator_get(dev, "vref");
+	if (IS_ERR(ti_dac->vref))
+		return PTR_ERR(ti_dac->vref);
+
+	ret = regulator_enable(ti_dac->vref);
+	if (ret < 0)
+		return ret;
+
+	mutex_init(&ti_dac->lock);
+	ret = iio_device_register(indio_dev);
+	if (ret) {
+		mutex_destroy(&ti_dac->lock);
+		regulator_disable(ti_dac->vref);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int ti_dac_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct ti_dac_chip *ti_dac = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+	mutex_destroy(&ti_dac->lock);
+	regulator_disable(ti_dac->vref);
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id ti_dac_of_id[] = {
+	{ .compatible = "ti,dac082s085" },
+	{ .compatible = "ti,dac102s085" },
+	{ .compatible = "ti,dac122s085" },
+	{ .compatible = "ti,dac084s085" },
+	{ .compatible = "ti,dac104s085" },
+	{ .compatible = "ti,dac124s085" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ti_dac_of_id);
+#endif
+
+static const struct spi_device_id ti_dac_spi_id[] = {
+	{ "dac082s085" },
+	{ "dac102s085" },
+	{ "dac122s085" },
+	{ "dac084s085" },
+	{ "dac104s085" },
+	{ "dac124s085" },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, ti_dac_spi_id);
+
+static struct spi_driver ti_dac_driver = {
+	.driver = {
+		.name		= "ti-dac082s085",
+		.of_match_table	= of_match_ptr(ti_dac_of_id),
+	},
+	.probe	  = ti_dac_probe,
+	.remove   = ti_dac_remove,
+	.id_table = ti_dac_spi_id,
+};
+module_spi_driver(ti_dac_driver);
+
+MODULE_AUTHOR("Lukas Wunner <lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org>");
+MODULE_DESCRIPTION("Texas Instruments 8/10/12-bit 2/4-channel DAC driver");
+MODULE_LICENSE("GPL v2");
-- 
2.11.0

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Re: [PATCH 2/2] iio: dac: Add Texas Instruments 8/10/12-bit 2/4-channel DAC driver

[Jonathan Cameron]

On Tue, 5 Sep 2017 11:27:00 +0200
Lukas Wunner <lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org> wrote:

> The DACrrcS085 (rr = 08/10/12, c = 2/4) family of SPI DACs was
> inherited by TI when they acquired National Semiconductor in 2011.
> This driver was developed for and tested with the DAC082S085 built into
> the Revolution Pi by KUNBUS, but should work with any of the other
> chips as they share the same programming interface.
> 
> There is also a family of I2C DACs with just a single channel called
> DACrr1C08x (rr = 08/10/12, x = 1/5).  Their programming interface is
> very similar and it should be possible to extend the driver for these
> chips with moderate effort.  Alternatively they could be integrated into
> ad5446.c.  (The AD5301/AD5311/AD5321 use different power-down modes but
> otherwise appear to be comparable.)
> 
> Furthermore there is a family of 8-channel DACs called DACrr8S085
> (rr = 08/10/12) as well as two 16-bit DACs called DAC161Sxxx
> (xxx = 055/997).  These are more complicated devices with support for
> daisy-chaining and the ability to power down each channel separately.
> They could either be handled by a separate driver or integrated into the
> present driver with a larger effort.
> 
> Cc: Mathias Duckeck <m.duckeck-XB/JSsFECOqzQB+pC5nmwQ@public.gmane.org>
> Signed-off-by: Lukas Wunner <lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org>

Very nice.  A few really minor comments inline.

Thanks,

Jonathan
> ---
>  Documentation/ABI/testing/sysfs-bus-iio |   1 +
>  drivers/iio/dac/Kconfig                 |  10 +
>  drivers/iio/dac/Makefile                |   1 +
>  drivers/iio/dac/ti-dac082s085.c         | 347 ++++++++++++++++++++++++++++++++
>  4 files changed, 359 insertions(+)
>  create mode 100644 drivers/iio/dac/ti-dac082s085.c
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
> index 7eead5f97e02..407e4d1024ee 100644
> --- a/Documentation/ABI/testing/sysfs-bus-iio
> +++ b/Documentation/ABI/testing/sysfs-bus-iio
> @@ -522,6 +522,7 @@ Description:
>  		Specifies the output powerdown mode.
>  		DAC output stage is disconnected from the amplifier and
>  		1kohm_to_gnd: connected to ground via an 1kOhm resistor,
> +		2.5kohm_to_gnd: connected to ground via a 2.5kOhm resistor,
>  		6kohm_to_gnd: connected to ground via a 6kOhm resistor,
>  		20kohm_to_gnd: connected to ground via a 20kOhm resistor,
>  		90kohm_to_gnd: connected to ground via a 90kOhm resistor,
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index 25bed2d7d2b9..716fcb1610dd 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -300,6 +300,16 @@ config STM32_DAC
>  config STM32_DAC_CORE
>  	tristate
>  
> +config TI_DAC082S085
> +	tristate "Texas Instruments 8/10/12-bit 2/4-channel DAC driver"
> +	depends on SPI_MASTER
> +	help
> +	  Driver for the Texas Instruments (formerly National Semiconductor)
> +	  DAC082S085, DAC102S085, DAC122S085, DAC084S085, DAC104S085 and
> +	  DAC124S085.
> +
> +	  If compiled as a module, it will be called ti-dac082s085.
> +
>  config VF610_DAC
>  	tristate "Vybrid vf610 DAC driver"
>  	depends on OF
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index 603587cc2f07..1a2dd507b4d8 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -32,4 +32,5 @@ obj-$(CONFIG_MCP4725) += mcp4725.o
>  obj-$(CONFIG_MCP4922) += mcp4922.o
>  obj-$(CONFIG_STM32_DAC_CORE) += stm32-dac-core.o
>  obj-$(CONFIG_STM32_DAC) += stm32-dac.o
> +obj-$(CONFIG_TI_DAC082S085) += ti-dac082s085.o
>  obj-$(CONFIG_VF610_DAC) += vf610_dac.o
> diff --git a/drivers/iio/dac/ti-dac082s085.c b/drivers/iio/dac/ti-dac082s085.c
> new file mode 100644
> index 000000000000..22fdce512a09
> --- /dev/null
> +++ b/drivers/iio/dac/ti-dac082s085.c
> @@ -0,0 +1,347 @@
> +/*
> + * ti-dac082s085.c - Texas Instruments 8/10/12-bit 2/4-channel DAC driver
> + *
> + * Copyright (C) 2017 KUNBUS GmbH
> + *
> + * http://www.ti.com/lit/ds/symlink/dac082s085.pdf
> + * http://www.ti.com/lit/ds/symlink/dac102s085.pdf
> + * http://www.ti.com/lit/ds/symlink/dac122s085.pdf
> + * http://www.ti.com/lit/ds/symlink/dac084s085.pdf
> + * http://www.ti.com/lit/ds/symlink/dac104s085.pdf
> + * http://www.ti.com/lit/ds/symlink/dac124s085.pdf
> + *
> + * 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.
> + */
> +
> +#include <linux/iio/iio.h>
> +#include <linux/module.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/spi/spi.h>
> +
> +/**
> + * struct ti_dac_chip - TI DAC chip
> + * @lock: protects write sequences
> + * @vref: regulator generating Vref
> + * @mesg: SPI message to perform a write
> + * @xfer: SPI transfer used by @mesg
> + * @buf: buffer for @xfer
> + * @val: cached value of each output
> + * @powerdown: whether the chip is powered down
> + * @powerdown_mode: selected by the user
> + * @resolution: resolution of the chip
> + */
> +struct ti_dac_chip {
> +	struct mutex lock;
> +	struct regulator *vref;
> +	struct spi_message mesg;
> +	struct spi_transfer xfer;
> +	u8 buf[2] ____cacheline_aligned;
> +	u16 val[4];
> +	bool powerdown;
> +	u8 powerdown_mode;
> +	u8 resolution;
> +};
> +
> +#define WRITE_NOT_UPDATE(chan)	(0x00 | (chan) << 6)
> +#define WRITE_AND_UPDATE(chan)	(0x10 | (chan) << 6)
> +#define WRITE_ALL_UPDATE	 0x20
> +#define POWERDOWN(mode) 	(0x30 | ((mode) + 1) << 6)
> +
> +static int ti_dac_cmd(struct ti_dac_chip *ti_dac, u8 cmd, u16 val)
> +{
> +	u8 shift = 12 - ti_dac->resolution;
> +
> +	ti_dac->buf[0] = cmd | (val >> (8 - shift));
> +	ti_dac->buf[1] = (val << shift) & 0xff;
> +	return spi_sync(ti_dac->mesg.spi, &ti_dac->mesg);
> +}
> +
> +static const char * const ti_dac_powerdown_modes[] = {
> +	"2.5kohm_to_gnd", "100kohm_to_gnd", "three_state",
> +};
> +
> +static int ti_dac_get_powerdown_mode(struct iio_dev *indio_dev,
> +				     const struct iio_chan_spec *chan)
> +{
> +	struct ti_dac_chip *ti_dac = iio_priv(indio_dev);
> +
> +	return ti_dac->powerdown_mode;
> +}
> +
> +static int ti_dac_set_powerdown_mode(struct iio_dev *indio_dev,
> +				     const struct iio_chan_spec *chan,
> +				     unsigned int mode)
> +{
> +	struct ti_dac_chip *ti_dac = iio_priv(indio_dev);
> +	int ret;
> +
> +	if (ti_dac->powerdown_mode == mode)
> +		return 0;
> +
> +	mutex_lock(&ti_dac->lock);
> +	if (ti_dac->powerdown) {
> +		ret = ti_dac_cmd(ti_dac, POWERDOWN(mode), 0);
> +		if (ret) {

I'd slightly prefer a goto to use the unlock already found below.

> +			mutex_unlock(&ti_dac->lock);
> +			return ret;
> +		}
> +	}
> +	ti_dac->powerdown_mode = mode;
> +	mutex_unlock(&ti_dac->lock);

nitpick time : blank line here

> +	return 0;
> +}
> +
> +static const struct iio_enum ti_dac_powerdown_mode = {
> +	.items = ti_dac_powerdown_modes,
> +	.num_items = ARRAY_SIZE(ti_dac_powerdown_modes),
> +	.get = ti_dac_get_powerdown_mode,
> +	.set = ti_dac_set_powerdown_mode,
> +};
> +
> +static ssize_t ti_dac_read_powerdown(struct iio_dev *indio_dev,
> +				     uintptr_t private,
> +				     const struct iio_chan_spec *chan,
> +				     char *buf)
> +{
> +	struct ti_dac_chip *ti_dac = iio_priv(indio_dev);
> +
> +	return sprintf(buf, "%d\n", ti_dac->powerdown);
> +}
> +
> +static ssize_t ti_dac_write_powerdown(struct iio_dev *indio_dev,
> +				      uintptr_t private,
> +				      const struct iio_chan_spec *chan,
> +				      const char *buf, size_t len)
> +{
> +	struct ti_dac_chip *ti_dac = iio_priv(indio_dev);
> +	bool powerdown;
> +	int ret;
> +
> +	ret = strtobool(buf, &powerdown);
> +	if (ret)
> +		return ret;
> +
> +	if (ti_dac->powerdown == powerdown)
> +		return len;
> +
> +	mutex_lock(&ti_dac->lock);
> +	if (powerdown)
> +		ret = ti_dac_cmd(ti_dac, POWERDOWN(ti_dac->powerdown_mode), 0);
> +	else
> +		ret = ti_dac_cmd(ti_dac, WRITE_AND_UPDATE(0), ti_dac->val[0]);
> +	if (!ret)
> +		ti_dac->powerdown = powerdown;
> +	mutex_unlock(&ti_dac->lock);
> +
> +	return ret ? ret : len;
> +}
> +
> +static const struct iio_chan_spec_ext_info ti_dac_ext_info[] = {
> +	{
> +		.name	   = "powerdown",
> +		.read	   = ti_dac_read_powerdown,
> +		.write	   = ti_dac_write_powerdown,
> +		.shared	   = IIO_SHARED_BY_TYPE,
> +	},
> +	IIO_ENUM("powerdown_mode", IIO_SHARED_BY_TYPE, &ti_dac_powerdown_mode),
> +	IIO_ENUM_AVAILABLE("powerdown_mode", &ti_dac_powerdown_mode),
> +	{ },
> +};
> +
> +#define TI_DAC_CHANNEL(chan) {					\
> +	.type = IIO_VOLTAGE,					\
> +	.channel = (chan),					\
> +	.address = (chan),					\
> +	.indexed = true,					\
> +	.output = true,						\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> +	.ext_info = ti_dac_ext_info,				\
> +}
> +
> +static const struct iio_chan_spec ti_dac_channels[] = {
> +	TI_DAC_CHANNEL(0),
> +	TI_DAC_CHANNEL(1),
> +	TI_DAC_CHANNEL(2),
> +	TI_DAC_CHANNEL(3),
> +};
> +
> +static int ti_dac_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan,
> +			   int *val, int *val2, long mask)
> +{
> +	struct ti_dac_chip *ti_dac = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		*val = ti_dac->val[chan->channel];
> +		ret = IIO_VAL_INT;
> +		break;
> +
> +	case IIO_CHAN_INFO_SCALE:
> +		ret = regulator_get_voltage(ti_dac->vref);
> +		if (ret < 0)
> +			return ret;
> +
> +		*val = ret / 1000;
> +		*val2 = ti_dac->resolution;
> +		ret = IIO_VAL_FRACTIONAL_LOG2;
> +		break;
> +
> +	default:
> +		ret = -EINVAL;
> +	}
> +
> +	return ret;
> +}
> +
> +static int ti_dac_write_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int val, int val2, long mask)
> +{
> +	struct ti_dac_chip *ti_dac = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		if (ti_dac->val[chan->channel] == val)
> +			return 0;
> +
> +		if (val >= (1 << ti_dac->resolution) || val < 0)
> +			return -EINVAL;
> +
> +		if (ti_dac->powerdown)
> +			return -EHOSTDOWN;

Hmm. That's a relatively unusual error to find in a driver.
I'd have gone with -EBUSY to indicate that you can't do it now, but might
be able to in future..

> +
> +		mutex_lock(&ti_dac->lock);
> +		ret = ti_dac_cmd(ti_dac, WRITE_AND_UPDATE(chan->channel), val);
> +		if (!ret)
> +			ti_dac->val[chan->channel] = val;
> +		mutex_unlock(&ti_dac->lock);
> +		break;
> +
> +	default:
> +		ret = -EINVAL;
> +	}
> +
> +	return ret;
> +}
> +
> +static int ti_dac_write_raw_get_fmt(struct iio_dev *indio_dev,
> +				    struct iio_chan_spec const *chan, long mask)
> +{
> +	return IIO_VAL_INT;
> +}
> +
> +static const struct iio_info ti_dac_info = {
> +	.read_raw	   = ti_dac_read_raw,
> +	.write_raw	   = ti_dac_write_raw,
> +	.write_raw_get_fmt = ti_dac_write_raw_get_fmt,
> +};
> +
> +static int ti_dac_probe(struct spi_device *spi)
> +{
> +	struct device *dev = &spi->dev;
> +	struct ti_dac_chip *ti_dac;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*ti_dac));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	indio_dev->dev.parent = dev;
> +	indio_dev->info = &ti_dac_info;
> +	indio_dev->name = spi->modalias;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = ti_dac_channels;
> +	spi_set_drvdata(spi, indio_dev);
> +
> +	ti_dac = iio_priv(indio_dev);
> +	ti_dac->xfer.tx_buf = &ti_dac->buf;
> +	ti_dac->xfer.len = sizeof(ti_dac->buf);
> +	spi_message_init_with_transfers(&ti_dac->mesg, &ti_dac->xfer, 1);
> +	ti_dac->mesg.spi = spi;
> +
> +	ret = sscanf(spi->modalias, "dac%2hhu%1d",
> +		     &ti_dac->resolution, &indio_dev->num_channels);
> +	WARN_ON(ret != 2);

Whilst this seems nice and clear now, it may not work if this driver
had additional parts added in future. 

I would prefer an explicit table with this information in it and
use an enum to reference into it.

This is a bit 'too clever' :)

> +
> +	ret = ti_dac_cmd(ti_dac, WRITE_ALL_UPDATE, 0);
> +	if (ret) {
> +		dev_err(dev, "failed to initialize outputs to 0\n");
> +		return ret;
> +	}
> +
> +	ti_dac->vref = devm_regulator_get(dev, "vref");
> +	if (IS_ERR(ti_dac->vref))
> +		return PTR_ERR(ti_dac->vref);
> +
> +	ret = regulator_enable(ti_dac->vref);
> +	if (ret < 0)
> +		return ret;
> +
> +	mutex_init(&ti_dac->lock);
> +	ret = iio_device_register(indio_dev);
> +	if (ret) {
> +		mutex_destroy(&ti_dac->lock);
> +		regulator_disable(ti_dac->vref);
> +		return ret;
> +	}
> +
> +	return 0;
Trivial: 

return ret; here and get rid of it in the brackets above.

> +}
> +
> +static int ti_dac_remove(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> +	struct ti_dac_chip *ti_dac = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +	mutex_destroy(&ti_dac->lock);
> +	regulator_disable(ti_dac->vref);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id ti_dac_of_id[] = {
> +	{ .compatible = "ti,dac082s085" },
> +	{ .compatible = "ti,dac102s085" },
> +	{ .compatible = "ti,dac122s085" },
> +	{ .compatible = "ti,dac084s085" },
> +	{ .compatible = "ti,dac104s085" },
> +	{ .compatible = "ti,dac124s085" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, ti_dac_of_id);
> +#endif
> +
> +static const struct spi_device_id ti_dac_spi_id[] = {
> +	{ "dac082s085" },
> +	{ "dac102s085" },
> +	{ "dac122s085" },
> +	{ "dac084s085" },
> +	{ "dac104s085" },
> +	{ "dac124s085" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(spi, ti_dac_spi_id);
> +
> +static struct spi_driver ti_dac_driver = {
> +	.driver = {
> +		.name		= "ti-dac082s085",
> +		.of_match_table	= of_match_ptr(ti_dac_of_id),
> +	},
> +	.probe	  = ti_dac_probe,
> +	.remove   = ti_dac_remove,
> +	.id_table = ti_dac_spi_id,
> +};
> +module_spi_driver(ti_dac_driver);
> +
> +MODULE_AUTHOR("Lukas Wunner <lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org>");
> +MODULE_DESCRIPTION("Texas Instruments 8/10/12-bit 2/4-channel DAC driver");
> +MODULE_LICENSE("GPL v2");

Re: [PATCH 2/2] iio: dac: Add Texas Instruments 8/10/12-bit 2/4-channel DAC driver

[Lukas Wunner]

On Sun, Sep 10, 2017 at 04:11:08PM +0100, Jonathan Cameron wrote:
> On Tue, 5 Sep 2017 11:27:00 +0200 Lukas Wunner <lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org> wrote:
> > The DACrrcS085 (rr = 08/10/12, c = 2/4) family of SPI DACs was
> > inherited by TI when they acquired National Semiconductor in 2011.
> 
> Very nice.  A few really minor comments inline.

D'accord on all your comments except this one:


> > +	ret = sscanf(spi->modalias, "dac%2hhu%1d",
> > +		     &ti_dac->resolution, &indio_dev->num_channels);
> > +	WARN_ON(ret != 2);
> 
> Whilst this seems nice and clear now, it may not work if this driver
> had additional parts added in future. 
> 
> I would prefer an explicit table with this information in it and
> use an enum to reference into it.
> 
> This is a bit 'too clever' :)

Hm, I looked at the other SPI DACs available from TI and their programming
interface is sufficiently different that they don't lend themselves all
too well for integration into this driver.  There might be DACs from other
vendors with a similar programming interface.

What I *could* do is encode the resolution and number of channels in the
driver_data field of the spi MODULE_DEVICE_TABLE like this:

static const struct spi_device_id ti_dac_spi_id[] = {
	{ "dac082s085",  8 << 8 + 2 },
	{ "dac102s085", 10 << 8 + 2 },
	...

Then instead of reading the information from the modalias I'd read them
from driver_data.  However it looks a bit redundant and silly to me.
Can we add this extra complexity when the need for it actually arises?

Thanks,

Lukas
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Re: [PATCH 2/2] iio: dac: Add Texas Instruments 8/10/12-bit 2/4-channel DAC driver

[Jonathan Cameron]

On Sat, 7 Oct 2017 11:13:12 +0200
Lukas Wunner <lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org> wrote:

> On Sun, Sep 10, 2017 at 04:11:08PM +0100, Jonathan Cameron wrote:
> > On Tue, 5 Sep 2017 11:27:00 +0200 Lukas Wunner <lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org> wrote:  
> > > The DACrrcS085 (rr = 08/10/12, c = 2/4) family of SPI DACs was
> > > inherited by TI when they acquired National Semiconductor in 2011.  
> > 
> > Very nice.  A few really minor comments inline.  
> 
> D'accord on all your comments except this one:
> 
> 
> > > +	ret = sscanf(spi->modalias, "dac%2hhu%1d",
> > > +		     &ti_dac->resolution, &indio_dev->num_channels);
> > > +	WARN_ON(ret != 2);  
> > 
> > Whilst this seems nice and clear now, it may not work if this driver
> > had additional parts added in future. 
> > 
> > I would prefer an explicit table with this information in it and
> > use an enum to reference into it.
> > 
> > This is a bit 'too clever' :)  
> 
> Hm, I looked at the other SPI DACs available from TI and their programming
> interface is sufficiently different that they don't lend themselves all
> too well for integration into this driver.  There might be DACs from other
> vendors with a similar programming interface.
> 
> What I *could* do is encode the resolution and number of channels in the
> driver_data field of the spi MODULE_DEVICE_TABLE like this:
> 
> static const struct spi_device_id ti_dac_spi_id[] = {
> 	{ "dac082s085",  8 << 8 + 2 },
> 	{ "dac102s085", 10 << 8 + 2 },
> 	...
> 
> Then instead of reading the information from the modalias I'd read them
> from driver_data.  However it looks a bit redundant and silly to me.
> Can we add this extra complexity when the need for it actually arises?

Do it the simple if slightly more lengthy way. It's easier to review
and less likely to be fragile in future.

enum dac082s085_devices {
	DAC082S085,
	DAC102S085
};

struct dac082s085_device_info {
	int resolution;
	int num_channels;
};

static const struct
	dac082s085_device_info dac082s085_devices[dac082s085_devices] = {
		DAC082S085 = {
			.resolution = 8,
			.num_channels = 2,
		},
	....		
};

Then pick the relevant structure when you probe.

It's long code, but it is really easy to tell if it is correct.
Here we are trading off verbosity for maintainability.

Jonathan

> 
> Thanks,
> 
> Lukas
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Re: [PATCH 1/2] dt-bindings: iio: dac: ti-dac082s085: Document new driver

[Jonathan Cameron]

On Tue, 5 Sep 2017 11:27:00 +0200
Lukas Wunner <lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org> wrote:

> Add device tree bindings for Texas Instruments 8/10/12-bit 2/4-channel
> DAC driver.
> 
> Cc: Mathias Duckeck <m.duckeck-XB/JSsFECOqzQB+pC5nmwQ@public.gmane.org>
> Signed-off-by: Lukas Wunner <lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org>

Looks good for me.  Lets see what Mark / Rob think.

Thanks,

Jonathan

> ---
>  .../devicetree/bindings/iio/dac/ti-dac082s085.txt  | 34 ++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/dac/ti-dac082s085.txt
> 
> diff --git a/Documentation/devicetree/bindings/iio/dac/ti-dac082s085.txt b/Documentation/devicetree/bindings/iio/dac/ti-dac082s085.txt
> new file mode 100644
> index 000000000000..9cb0e10df704
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/dac/ti-dac082s085.txt
> @@ -0,0 +1,34 @@
> +Texas Instruments 8/10/12-bit 2/4-channel DAC driver
> +
> +Required properties:
> + - compatible:		Must be one of:
> +			"ti,dac082s085"
> +			"ti,dac102s085"
> +			"ti,dac122s085"
> +			"ti,dac084s085"
> +			"ti,dac104s085"
> +			"ti,dac124s085"
> + - reg: 		Chip select number.
> + - spi-cpha, spi-cpol:	SPI mode (0,1) or (1,0) must be used, so specify
> +			either spi-cpha or spi-cpol (but not both).
> + - vref-supply: 	Phandle to the external reference voltage supply.
> +
> +For other required and optional properties of SPI slave nodes please refer to
> +../../spi/spi-bus.txt.
> +
> +Example:
> +	vref_2v5_reg: regulator-vref {
> +		compatible = "regulator-fixed";
> +		regulator-name = "2v5";
> +		regulator-min-microvolt = <2500000>;
> +		regulator-max-microvolt = <2500000>;
> +		regulator-always-on;
> +	};
> +
> +	dac@0 {
> +		compatible = "ti,dac082s085";
> +		reg = <0>;
> +		spi-max-frequency = <40000000>;
> +		spi-cpol;
> +		vref-supply = <&vref_2v5_reg>;
> +	};

Re: [PATCH 1/2] dt-bindings: iio: dac: ti-dac082s085: Document new driver

[Rob Herring]

On Tue, Sep 05, 2017 at 11:27:00AM +0200, Lukas Wunner wrote:
> Add device tree bindings for Texas Instruments 8/10/12-bit 2/4-channel
> DAC driver.
> 
> Cc: Mathias Duckeck <m.duckeck-XB/JSsFECOqzQB+pC5nmwQ@public.gmane.org>
> Signed-off-by: Lukas Wunner <lukas-JFq808J9C/izQB+pC5nmwQ@public.gmane.org>
> ---
>  .../devicetree/bindings/iio/dac/ti-dac082s085.txt  | 34 ++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/dac/ti-dac082s085.txt

Acked-by: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> 

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