[1/3] iio: adc: ltc2496: provide device tree binding document
diff mbox series

Message ID 20191111214025.18310-1-u.kleine-koenig@pengutronix.de
State Changes Requested
Headers show
Series
  • [1/3] iio: adc: ltc2496: provide device tree binding document
Related show

Checks

Context Check Description
robh/checkpatch success

Commit Message

Uwe Kleine-König Nov. 11, 2019, 9:40 p.m. UTC
The ADC only requires the standard stuff for spi devices and a reference
voltage.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 .../devicetree/bindings/iio/adc/ltc2496.txt       | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/ltc2496.txt

Comments

Ardelean, Alexandru Nov. 12, 2019, 6:57 a.m. UTC | #1
On Mon, 2019-11-11 at 22:40 +0100, Uwe Kleine-König wrote:
> The ADC only requires the standard stuff for spi devices and a reference
> voltage.
> 

Hey,

Thanks for the patch.

DT bindings must be in YAML format.
But in this case, you can probably extend the existing
"Documentation/devicetree/bindings/iio/adc/ltc2497.txt".

You don't need to create new file altogether.

> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
>  .../devicetree/bindings/iio/adc/ltc2496.txt       | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/ltc2496.txt
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/ltc2496.txt
> b/Documentation/devicetree/bindings/iio/adc/ltc2496.txt
> new file mode 100644
> index 000000000000..d44ab45b26ea
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/ltc2496.txt
> @@ -0,0 +1,15 @@
> +* Linear Technology / Analog Devices LTC2496 ADC
> +
> +Required properties:
> + - compatible: Must be "lltc,ltc2496"
> + - vref-supply: The regulator supply for ADC reference voltage
> + - further properties required for spi device nodes according to
> +   Documentation/devicetree/bindings/spi/spi-controller.yaml
> +
> +Example:
> +	ltc2497: adc@76 {
> +		compatible = "lltc,ltc2496";
> +		reg = <0>;
> +		vref-supply = <&ltc249x_reg>;
> +		spi-max-frequency = <2000000>;
> +	};
Uwe Kleine-König Nov. 12, 2019, 7:04 a.m. UTC | #2
Hello Alexandru,

On Tue, Nov 12, 2019 at 06:57:49AM +0000, Ardelean, Alexandru wrote:
> On Mon, 2019-11-11 at 22:40 +0100, Uwe Kleine-König wrote:
> > The ADC only requires the standard stuff for spi devices and a reference
> > voltage.
> 
> DT bindings must be in YAML format.

Yeah, I noticed this trend. But given that I only saw .txt files for
iio, I thought I'd stick to that.

> But in this case, you can probably extend the existing
> "Documentation/devicetree/bindings/iio/adc/ltc2497.txt".

I considered that shortly, but as the ltc2497 is an i2c device and the
ltc2496 uses spi I chose to create another simple document instead of
complicating the existing one by describing two nearly orthogonal sets
of properties.

Best regards
Uwe
Ardelean, Alexandru Nov. 12, 2019, 7:14 a.m. UTC | #3
On Mon, 2019-11-11 at 22:40 +0100, Uwe Kleine-König wrote:
> This allows to share the data for the ltc2496 driver added in
> the next commit that is an SPI variant of the ltc2497.
> 

Hey,

For this split, maybe take a look at adxl372-i2c.c & adxl372-spi.c.
I think that one is similar to how this split could be.


> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
>  drivers/iio/adc/Makefile  |  2 +-
>  drivers/iio/adc/ltc2497.c | 81 +++++----------------------------------
>  drivers/iio/adc/ltc249x.c | 72 ++++++++++++++++++++++++++++++++++
>  drivers/iio/adc/ltc249x.h | 10 +++++
>  4 files changed, 93 insertions(+), 72 deletions(-)
>  create mode 100644 drivers/iio/adc/ltc249x.c
>  create mode 100644 drivers/iio/adc/ltc249x.h
> 
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index ef9cc485fb67..660242c2cca7 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -47,7 +47,7 @@ obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o
>  obj-$(CONFIG_LPC32XX_ADC) += lpc32xx_adc.o
>  obj-$(CONFIG_LTC2471) += ltc2471.o
>  obj-$(CONFIG_LTC2485) += ltc2485.o
> -obj-$(CONFIG_LTC2497) += ltc2497.o
> +obj-$(CONFIG_LTC2497) += ltc2497.o ltc249x.o

Typically, we name the common/core files "ltc2497-core.o".
Or you can leave this unchanged and just add a new "ltc2497-i2c.o"

In this case, you also need some new Kconfig symbols. [patch2-note1]

And this would be

obj-$(CONFIG_LTC2497) += ltc2497.o
+obj-$(CONFIG_LTC2497_I2C) += ltc2497-i2c.o

Because, the new driver would be:

obj-$(CONFIG_LTC2497) += ltc2497.o
+obj-$(CONFIG_LTC2497_I2C) += ltc2497-
i2c.o
+obj-$(CONFIG_LTC2497_SPI) += ltc2497-spi.o

So, LTC2496 would go into "ltc2497-spi."

>  obj-$(CONFIG_MAX1027) += max1027.o
>  obj-$(CONFIG_MAX11100) += max11100.o
>  obj-$(CONFIG_MAX1118) += max1118.o
> diff --git a/drivers/iio/adc/ltc2497.c b/drivers/iio/adc/ltc2497.c
> index 470406032720..e86fe42f1598 100644
> --- a/drivers/iio/adc/ltc2497.c
> +++ b/drivers/iio/adc/ltc2497.c
> @@ -16,12 +16,7 @@
>  #include <linux/of.h>
>  #include <linux/regulator/consumer.h>
>  
> -#define LTC2497_ENABLE			0xA0
> -#define LTC2497_SGL			BIT(4)
> -#define LTC2497_DIFF			0
> -#define LTC2497_SIGN			BIT(3)
> -#define LTC2497_CONFIG_DEFAULT		LTC2497_ENABLE
> -#define LTC2497_CONVERSION_TIME_MS	150ULL
> +#include "ltc249x.h"
>  
>  struct ltc2497_st {
>  	struct i2c_client *client;
> @@ -41,18 +36,18 @@ static int ltc2497_wait_conv(struct ltc2497_st *st)
>  
>  	time_elapsed = ktime_ms_delta(ktime_get(), st->time_prev);
>  
> -	if (time_elapsed < LTC2497_CONVERSION_TIME_MS) {
> +	if (time_elapsed < LTC249X_CONVERSION_TIME_MS) {

You can leave all LTC2497_xxx macros/definitions unchanged.
If LTC2496 has something new, you can add a new LTC2496_specific_xxx
definition and use it.


>  		/* delay if conversion time not passed
>  		 * since last read or write
>  		 */
>  		if (msleep_interruptible(
> -		    LTC2497_CONVERSION_TIME_MS - time_elapsed))
> +		    LTC249X_CONVERSION_TIME_MS - time_elapsed))
>  			return -ERESTARTSYS;
>  
>  		return 0;
>  	}
>  
> -	if (time_elapsed - LTC2497_CONVERSION_TIME_MS <= 0) {
> +	if (time_elapsed - LTC249X_CONVERSION_TIME_MS <= 0) {
>  		/* We're in automatic mode -
>  		 * so the last reading is stil not outdated
>  		 */
> @@ -73,11 +68,11 @@ static int ltc2497_read(struct ltc2497_st *st, u8
> address, int *val)
>  
>  	if (ret || st->addr_prev != address) {
>  		ret = i2c_smbus_write_byte(st->client,
> -					   LTC2497_ENABLE | address);
> +					   LTC249X_ENABLE | address);
>  		if (ret < 0)
>  			return ret;
>  		st->addr_prev = address;
> -		if (msleep_interruptible(LTC2497_CONVERSION_TIME_MS))
> +		if (msleep_interruptible(LTC249X_CONVERSION_TIME_MS))
>  			return -ERESTARTSYS;
>  	}
>  	ret = i2c_master_recv(client, (char *)&st->buf, 3);
> @@ -127,62 +122,6 @@ static int ltc2497_read_raw(struct iio_dev
> *indio_dev,
>  	}
>  }
>  
> -#define LTC2497_CHAN(_chan, _addr, _ds_name) { \
> -	.type = IIO_VOLTAGE, \
> -	.indexed = 1, \
> -	.channel = (_chan), \
> -	.address = (_addr | (_chan / 2) | ((_chan & 1) ? LTC2497_SIGN :
> 0)), \
> -	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> -	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> -	.datasheet_name = (_ds_name), \
> -}
> -
> -#define LTC2497_CHAN_DIFF(_chan, _addr) { \
> -	.type = IIO_VOLTAGE, \
> -	.indexed = 1, \
> -	.channel = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 1 : 0), \
> -	.channel2 = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 0 : 1),\
> -	.address = (_addr | _chan), \
> -	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> -	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> -	.differential = 1, \
> -}
> -
> -static const struct iio_chan_spec ltc2497_channel[] = {
> -	LTC2497_CHAN(0, LTC2497_SGL, "CH0"),
> -	LTC2497_CHAN(1, LTC2497_SGL, "CH1"),
> -	LTC2497_CHAN(2, LTC2497_SGL, "CH2"),
> -	LTC2497_CHAN(3, LTC2497_SGL, "CH3"),
> -	LTC2497_CHAN(4, LTC2497_SGL, "CH4"),
> -	LTC2497_CHAN(5, LTC2497_SGL, "CH5"),
> -	LTC2497_CHAN(6, LTC2497_SGL, "CH6"),
> -	LTC2497_CHAN(7, LTC2497_SGL, "CH7"),
> -	LTC2497_CHAN(8, LTC2497_SGL, "CH8"),
> -	LTC2497_CHAN(9, LTC2497_SGL, "CH9"),
> -	LTC2497_CHAN(10, LTC2497_SGL, "CH10"),
> -	LTC2497_CHAN(11, LTC2497_SGL, "CH11"),
> -	LTC2497_CHAN(12, LTC2497_SGL, "CH12"),
> -	LTC2497_CHAN(13, LTC2497_SGL, "CH13"),
> -	LTC2497_CHAN(14, LTC2497_SGL, "CH14"),
> -	LTC2497_CHAN(15, LTC2497_SGL, "CH15"),
> -	LTC2497_CHAN_DIFF(0, LTC2497_DIFF),
> -	LTC2497_CHAN_DIFF(1, LTC2497_DIFF),
> -	LTC2497_CHAN_DIFF(2, LTC2497_DIFF),
> -	LTC2497_CHAN_DIFF(3, LTC2497_DIFF),
> -	LTC2497_CHAN_DIFF(4, LTC2497_DIFF),
> -	LTC2497_CHAN_DIFF(5, LTC2497_DIFF),
> -	LTC2497_CHAN_DIFF(6, LTC2497_DIFF),
> -	LTC2497_CHAN_DIFF(7, LTC2497_DIFF),
> -	LTC2497_CHAN_DIFF(0, LTC2497_DIFF | LTC2497_SIGN),
> -	LTC2497_CHAN_DIFF(1, LTC2497_DIFF | LTC2497_SIGN),
> -	LTC2497_CHAN_DIFF(2, LTC2497_DIFF | LTC2497_SIGN),
> -	LTC2497_CHAN_DIFF(3, LTC2497_DIFF | LTC2497_SIGN),
> -	LTC2497_CHAN_DIFF(4, LTC2497_DIFF | LTC2497_SIGN),
> -	LTC2497_CHAN_DIFF(5, LTC2497_DIFF | LTC2497_SIGN),
> -	LTC2497_CHAN_DIFF(6, LTC2497_DIFF | LTC2497_SIGN),
> -	LTC2497_CHAN_DIFF(7, LTC2497_DIFF | LTC2497_SIGN),
> -};
> -
>  static const struct iio_info ltc2497_info = {
>  	.read_raw = ltc2497_read_raw,
>  };
> @@ -211,8 +150,8 @@ static int ltc2497_probe(struct i2c_client *client,
>  	indio_dev->name = id->name;
>  	indio_dev->info = &ltc2497_info;
>  	indio_dev->modes = INDIO_DIRECT_MODE;
> -	indio_dev->channels = ltc2497_channel;
> -	indio_dev->num_channels = ARRAY_SIZE(ltc2497_channel);
> +	indio_dev->channels = ltc249x_channel;
> +	indio_dev->num_channels = ltc249x_num_channels;
>  
>  	st->ref = devm_regulator_get(&client->dev, "vref");
>  	if (IS_ERR(st->ref))
> @@ -231,11 +170,11 @@ static int ltc2497_probe(struct i2c_client *client,
>  		}
>  	}
>  
> -	ret = i2c_smbus_write_byte(st->client, LTC2497_CONFIG_DEFAULT);
> +	ret = i2c_smbus_write_byte(st->client, LTC249X_CONFIG_DEFAULT);
>  	if (ret < 0)
>  		goto err_array_unregister;
>  
> -	st->addr_prev = LTC2497_CONFIG_DEFAULT;
> +	st->addr_prev = LTC249X_CONFIG_DEFAULT;
>  	st->time_prev = ktime_get();
>  
>  	ret = iio_device_register(indio_dev);
> diff --git a/drivers/iio/adc/ltc249x.c b/drivers/iio/adc/ltc249x.c
> new file mode 100644
> index 000000000000..571fce7cc808
> --- /dev/null
> +++ b/drivers/iio/adc/ltc249x.c
> @@ -0,0 +1,72 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/driver.h>
> +#include <linux/module.h>
> +
> +#define LTC249X_SGL			BIT(4)
> +#define LTC249X_DIFF			0
> +#define LTC249X_SIGN			BIT(3)
> +
> +#define LTC249X_CHAN(_chan, _addr, _ds_name) { \
> +	.type = IIO_VOLTAGE, \
> +	.indexed = 1, \
> +	.channel = (_chan), \
> +	.address = (_addr | (_chan / 2) | ((_chan & 1) ? LTC249X_SIGN :
> 0)), \
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> +	.datasheet_name = (_ds_name), \
> +}
> +
> +#define LTC249X_CHAN_DIFF(_chan, _addr) { \
> +	.type = IIO_VOLTAGE, \
> +	.indexed = 1, \
> +	.channel = (_chan) * 2 + ((_addr) & LTC249X_SIGN ? 1 : 0), \
> +	.channel2 = (_chan) * 2 + ((_addr) & LTC249X_SIGN ? 0 : 1),\
> +	.address = (_addr | _chan), \
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> +	.differential = 1, \
> +}
> +
> +const struct iio_chan_spec ltc249x_channel[] = {
> +	LTC249X_CHAN(0, LTC249X_SGL, "CH0"),
> +	LTC249X_CHAN(1, LTC249X_SGL, "CH1"),
> +	LTC249X_CHAN(2, LTC249X_SGL, "CH2"),
> +	LTC249X_CHAN(3, LTC249X_SGL, "CH3"),
> +	LTC249X_CHAN(4, LTC249X_SGL, "CH4"),
> +	LTC249X_CHAN(5, LTC249X_SGL, "CH5"),
> +	LTC249X_CHAN(6, LTC249X_SGL, "CH6"),
> +	LTC249X_CHAN(7, LTC249X_SGL, "CH7"),
> +	LTC249X_CHAN(8, LTC249X_SGL, "CH8"),
> +	LTC249X_CHAN(9, LTC249X_SGL, "CH9"),
> +	LTC249X_CHAN(10, LTC249X_SGL, "CH10"),
> +	LTC249X_CHAN(11, LTC249X_SGL, "CH11"),
> +	LTC249X_CHAN(12, LTC249X_SGL, "CH12"),
> +	LTC249X_CHAN(13, LTC249X_SGL, "CH13"),
> +	LTC249X_CHAN(14, LTC249X_SGL, "CH14"),
> +	LTC249X_CHAN(15, LTC249X_SGL, "CH15"),
> +	LTC249X_CHAN_DIFF(0, LTC249X_DIFF),
> +	LTC249X_CHAN_DIFF(1, LTC249X_DIFF),
> +	LTC249X_CHAN_DIFF(2, LTC249X_DIFF),
> +	LTC249X_CHAN_DIFF(3, LTC249X_DIFF),
> +	LTC249X_CHAN_DIFF(4, LTC249X_DIFF),
> +	LTC249X_CHAN_DIFF(5, LTC249X_DIFF),
> +	LTC249X_CHAN_DIFF(6, LTC249X_DIFF),
> +	LTC249X_CHAN_DIFF(7, LTC249X_DIFF),
> +	LTC249X_CHAN_DIFF(0, LTC249X_DIFF | LTC249X_SIGN),
> +	LTC249X_CHAN_DIFF(1, LTC249X_DIFF | LTC249X_SIGN),
> +	LTC249X_CHAN_DIFF(2, LTC249X_DIFF | LTC249X_SIGN),
> +	LTC249X_CHAN_DIFF(3, LTC249X_DIFF | LTC249X_SIGN),
> +	LTC249X_CHAN_DIFF(4, LTC249X_DIFF | LTC249X_SIGN),
> +	LTC249X_CHAN_DIFF(5, LTC249X_DIFF | LTC249X_SIGN),
> +	LTC249X_CHAN_DIFF(6, LTC249X_DIFF | LTC249X_SIGN),
> +	LTC249X_CHAN_DIFF(7, LTC249X_DIFF | LTC249X_SIGN),
> +};
> +EXPORT_SYMBOL_NS_GPL(ltc249x_channel, LTC249X);

Maybe leave these channel definitions in  "ltc2497.o" file [which can be
the common one].
Instead of exporting these, maybe create a 

"int ltc2497_core_probe(struct device *dev)" function.

and add it in the "ltc2497.h" file.

You can call it with   "ltc2497_core_probe(&spi->dev)"   and
"ltc2497_core_probe(&client->dev)"

The beauty of this approach is that you also allocate the IIO device in the
common code.


> +
> +const int ltc249x_num_channels = ARRAY_SIZE(ltc249x_channel);
> +EXPORT_SYMBOL_NS_GPL(ltc249x_num_channels, LTC249X);
> +
> +MODULE_DESCRIPTION("common code for LTC2496/LTC2497 drivers");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/adc/ltc249x.h b/drivers/iio/adc/ltc249x.h
> new file mode 100644
> index 000000000000..dac8b5ed0ecf
> --- /dev/null
> +++ b/drivers/iio/adc/ltc249x.h
> @@ -0,0 +1,10 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +
> +#define LTC249X_ENABLE			0xA0
> +#define LTC249X_CONFIG_DEFAULT		LTC249X_ENABLE
> +#define LTC249X_CONVERSION_TIME_MS	150ULL
> +
> +extern const struct iio_chan_spec ltc249x_channel[];
> +extern const int ltc249x_num_channels;
> +
> +MODULE_IMPORT_NS(LTC249X);
Ardelean, Alexandru Nov. 12, 2019, 7:54 a.m. UTC | #4
On Mon, 2019-11-11 at 22:40 +0100, Uwe Kleine-König wrote:
> This chip is similar to the LTC2497 ADC, it just uses SPI instead of I2C
> and so has a slightly different protocol. The channel definitions are
> shared between the two drivers.

Much of this code is duplicated from the i2c/base ltc2497.o driver.

I would leave most of this code in the base/common driver and export the
i2c/spi read hooks.

You can check [as an example] the ad7606 driver.

That one passes some  bus_ops  struct from the SPI & Parallel drivers to
the common probe.

I agree that regmap isn't usable here, but a bus_ops struct [that is
defined in ltc2497.h] should be doable.

Thanks
Alex

> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
>  drivers/iio/adc/Kconfig   |  10 ++
>  drivers/iio/adc/Makefile  |   1 +
>  drivers/iio/adc/ltc2496.c | 208 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 219 insertions(+)
>  create mode 100644 drivers/iio/adc/ltc2496.c
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index f0af3a42f53c..deb86f6039b3 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -492,6 +492,16 @@ config LTC2485
>  	  To compile this driver as a module, choose M here: the module
> will be
>  	  called ltc2485.
>  
> +config LTC2496
> +	tristate "Linear Technology LTC2496 ADC driver"
> +	depends on SPI

Regarding [patch2-note1], this Kconfig symbols would be LTC2497_SPI

> +	help
> +	  Say yes here to build support for Linear Technology LTC2496
> +	  16-Bit 8-/16-Channel Delta Sigma ADC.
> +
> +	  To compile this driver as a module, choose M here: the module
> will be
> +	  called ltc2496.
> +
>  config LTC2497

Regarding [patch2-note1], this Kconfig symbols would become LTC2497_I2C.
And a new config LTC2497 could be added, but without any title, so that it
cannot be selected in menuconfig.

>  	tristate "Linear Technology LTC2497 ADC driver"
>  	depends on I2C
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 660242c2cca7..afe2b6db4a5e 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -47,6 +47,7 @@ obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o
>  obj-$(CONFIG_LPC32XX_ADC) += lpc32xx_adc.o
>  obj-$(CONFIG_LTC2471) += ltc2471.o
>  obj-$(CONFIG_LTC2485) += ltc2485.o
> +obj-$(CONFIG_LTC2496) += ltc2496.o ltc249x.o
>  obj-$(CONFIG_LTC2497) += ltc2497.o ltc249x.o
>  obj-$(CONFIG_MAX1027) += max1027.o
>  obj-$(CONFIG_MAX11100) += max11100.o
> diff --git a/drivers/iio/adc/ltc2496.c b/drivers/iio/adc/ltc2496.c
> new file mode 100644
> index 000000000000..0b0a7aa8987f
> --- /dev/null
> +++ b/drivers/iio/adc/ltc2496.c
> @@ -0,0 +1,208 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * ltc2496.c - Driver for Analog Devices/Linear Technology LTC2496 ADC
> + *
> + * Based on ltc2497.c which has
> + * Copyright (C) 2017 Analog Devices Inc.
> + *
> + * Licensed under the GPL-2.
> + *
> + * Datasheet: 
> https://www.analog.com/media/en/technical-documentation/data-sheets/2496fc.pdf
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/spi/spi.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/driver.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include "ltc249x.h"
> +
> +struct ltc2496_st {
> +	struct spi_device *spi;
> +	struct regulator *ref;
> +	ktime_t	time_prev;
> +	u8 addr_prev;
> +};
> +
> +static int ltc2496_wait_conv(struct ltc2496_st *st)
> +{
> +	s64 time_elapsed;
> +
> +	time_elapsed = ktime_ms_delta(ktime_get(), st->time_prev);
> +
> +	if (time_elapsed < LTC249X_CONVERSION_TIME_MS) {
> +		/* delay if conversion time not passed
> +		 * since last read or write
> +		 */
> +		if (msleep_interruptible(
> +		    LTC249X_CONVERSION_TIME_MS - time_elapsed))
> +			return -ERESTARTSYS;
> +
> +		return 0;
> +	}
> +
> +	if (time_elapsed - LTC249X_CONVERSION_TIME_MS <= 0) {
> +		/* We're in automatic mode -
> +		 * so the last reading is still not outdated
> +		 */
> +		return 0;
> +	}
> +
> +	return 1;
> +}
> +
> +static int ltc2496_read(struct ltc2496_st *st, u8 address, int *val)
> +{
> +	struct spi_device *spi = st->spi;
> +	int ret;
> +	unsigned char txbuf[3] = { LTC249X_ENABLE | address, };
> +	unsigned char rxbuf[3];
> +	struct spi_transfer t = {
> +		.tx_buf = txbuf,
> +		.rx_buf = rxbuf,
> +		.len = sizeof(txbuf),
> +	};
> +
> +	ret = ltc2496_wait_conv(st);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (ret || st->addr_prev != address) {
> +		ret = spi_sync_transfer(spi, &t, 1);
> +		if (ret < 0)
> +			return ret;
> +		st->addr_prev = address;
> +		if (msleep_interruptible(LTC249X_CONVERSION_TIME_MS))
> +			return -ERESTARTSYS;
> +	}
> +
> +	ret = spi_sync_transfer(spi, &t, 1);
> +	if (ret < 0)  {
> +		dev_err(&spi->dev, "spi_sync_transfer failed\n");
> +		return ret;
> +	}
> +	st->time_prev = ktime_get();
> +
> +	/* convert and shift the result,
> +	 * and finally convert from offset binary to signed integer
> +	 */
> +	*val = ((rxbuf[0] & 0x3f) << 12 | rxbuf[1] << 4 | rxbuf[2] >> 4)
> +		- (1 << 17);
> +
> +	return ret;
> +}
> +			    int *val, int *val2, long mask)
> +{
> +	struct ltc2496_st *st = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		mutex_lock(&indio_dev->mlock);
> +		ret = ltc2496_read(st, chan->address, val);
> +		mutex_unlock(&indio_dev->mlock);
> +		if (ret < 0)
> +			return ret;
> +
> +		return IIO_VAL_INT;
> +
> +	case IIO_CHAN_INFO_SCALE:
> +		ret = regulator_get_voltage(st->ref);
> +		if (ret < 0)
> +			return ret;
> +
> +		*val = ret / 1000;
> +		*val2 = 17;
> +
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_info ltc2496_info = {
> +	.read_raw = ltc2496_read_raw,
> +};
> +
> +static int ltc2496_probe(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev;
> +	struct ltc2496_st *st;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	st = iio_priv(indio_dev);
> +	spi_set_drvdata(spi, indio_dev);
> +	st->spi = spi;
> +
> +	indio_dev->dev.parent = &spi->dev;
> +	indio_dev->name = "ltc2496";
> +	indio_dev->info = &ltc2496_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = ltc249x_channel;
> +	indio_dev->num_channels = ltc249x_num_channels;
> +
> +	st->ref = devm_regulator_get(&spi->dev, "vref");
> +	if (IS_ERR(st->ref))
> +		return PTR_ERR(st->ref);
> +
> +	ret = regulator_enable(st->ref);
> +	if (ret < 0)
> +		return ret;
> +
> +	st->addr_prev = 0;
> +	st->time_prev = ktime_get();
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret < 0)
> +		goto err_regulator_disable;
> +
> +	return 0;
> +
> +err_regulator_disable:
> +	regulator_disable(st->ref);
> +
> +	return ret;
> +}
> +
> +static int ltc2496_remove(struct spi_device *spi)
> +{
> +	struct iio_dev *indio_dev = spi_get_drvdata(spi);
> +	struct ltc2496_st *st = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +	regulator_disable(st->ref);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id ltc2496_of_match[] = {
> +	{ .compatible = "lltc,ltc2496", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, ltc2496_of_match);
> +
> +static struct spi_driver ltc2496_driver = {
> +	.driver = {
> +		.name = "ltc2496",
> +		.of_match_table = of_match_ptr(ltc2496_of_match),
> +	},
> +	.probe = ltc2496_probe,
> +	.remove = ltc2496_remove,
> +};
> +module_spi_driver(ltc2496_driver);
> +
> +MODULE_AUTHOR("Uwe Kleine-König <u.kleine-könig@pengutronix.de>");
> +MODULE_DESCRIPTION("Linear Technology LTC2496 ADC driver");
> +MODULE_LICENSE("GPL v2");
Ardelean, Alexandru Nov. 12, 2019, 11:56 a.m. UTC | #5
On Tue, 2019-11-12 at 08:04 +0100, Uwe Kleine-König wrote:
> [External]
> 
> Hello Alexandru,
> 
> On Tue, Nov 12, 2019 at 06:57:49AM +0000, Ardelean, Alexandru wrote:
> > On Mon, 2019-11-11 at 22:40 +0100, Uwe Kleine-König wrote:
> > > The ADC only requires the standard stuff for spi devices and a
> > > reference
> > > voltage.
> > 
> > DT bindings must be in YAML format.
> 
> Yeah, I noticed this trend. But given that I only saw .txt files for
> iio, I thought I'd stick to that.
> 
> > But in this case, you can probably extend the existing
> > "Documentation/devicetree/bindings/iio/adc/ltc2497.txt".
> 
> I considered that shortly, but as the ltc2497 is an i2c device and the
> ltc2496 uses spi I chose to create another simple document instead of
> complicating the existing one by describing two nearly orthogonal sets
> of properties.

There are dt-bindings that cover both SPI & I2C.
I think ADXL372 does that too.


> 
> Best regards
> Uwe
>
Jonathan Cameron Nov. 16, 2019, 3:25 p.m. UTC | #6
On Tue, 12 Nov 2019 11:56:52 +0000
"Ardelean, Alexandru" <alexandru.Ardelean@analog.com> wrote:

> On Tue, 2019-11-12 at 08:04 +0100, Uwe Kleine-König wrote:
> > [External]
> > 
> > Hello Alexandru,
> > 
> > On Tue, Nov 12, 2019 at 06:57:49AM +0000, Ardelean, Alexandru wrote:  
> > > On Mon, 2019-11-11 at 22:40 +0100, Uwe Kleine-König wrote:  
> > > > The ADC only requires the standard stuff for spi devices and a
> > > > reference
> > > > voltage.  
> > > 
> > > DT bindings must be in YAML format.  
> > 
> > Yeah, I noticed this trend. But given that I only saw .txt files for
> > iio, I thought I'd stick to that.
> >   
> > > But in this case, you can probably extend the existing
> > > "Documentation/devicetree/bindings/iio/adc/ltc2497.txt".  
> > 
> > I considered that shortly, but as the ltc2497 is an i2c device and the
> > ltc2496 uses spi I chose to create another simple document instead of
> > complicating the existing one by describing two nearly orthogonal sets
> > of properties.  
> 
> There are dt-bindings that cover both SPI & I2C.
> I think ADXL372 does that too.
True, but in that case no real choice as the same part does both
bus types.  Here it's probably cleaner to just have a second document.

Thanks,

Jonathan

> 
> 
> > 
> > Best regards
> > Uwe
> >

Patch
diff mbox series

diff --git a/Documentation/devicetree/bindings/iio/adc/ltc2496.txt b/Documentation/devicetree/bindings/iio/adc/ltc2496.txt
new file mode 100644
index 000000000000..d44ab45b26ea
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/ltc2496.txt
@@ -0,0 +1,15 @@ 
+* Linear Technology / Analog Devices LTC2496 ADC
+
+Required properties:
+ - compatible: Must be "lltc,ltc2496"
+ - vref-supply: The regulator supply for ADC reference voltage
+ - further properties required for spi device nodes according to
+   Documentation/devicetree/bindings/spi/spi-controller.yaml
+
+Example:
+	ltc2497: adc@76 {
+		compatible = "lltc,ltc2496";
+		reg = <0>;
+		vref-supply = <&ltc249x_reg>;
+		spi-max-frequency = <2000000>;
+	};