Re: [PATCH 2/3] iio: adc: ltc2497: split channel definition in a separate module

["Ardelean, Alexandru" <alexandru.Ardelean@analog.com>]

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);