Re: [PATCH v3 1/4] staging: iio: ad7816: Switch to the gpio descriptor interface

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

On Fri, 2018-11-09 at 08:05 +0000, Ardelean, Alexandru wrote:
> On Fri, 2018-11-09 at 13:05 +0530, Nishad Kamdar wrote:
> > Use the gpiod interface for rdwr_pin, convert_pin and busy_pin
> > instead of the deprecated old non-descriptor interface.
> > 
> 
> Patch looks good.
> I do have some thoughts about it. See inline.
> 

Nevermind what I just said here; I just saw patch3: `iio: ad7816: Set RD/WR
pin and CONVST pin as outputs.`

This looks good as is in the context of the patch series.

> 
> > Signed-off-by: Nishad Kamdar <nishadkamdar@gmail.com>
> > ---
> >  drivers/staging/iio/adc/ad7816.c | 80 ++++++++++++++------------------
> >  1 file changed, 34 insertions(+), 46 deletions(-)
> > 
> > diff --git a/drivers/staging/iio/adc/ad7816.c
> > b/drivers/staging/iio/adc/ad7816.c
> > index bf76a8620bdb..12c4e0ab4713 100644
> > --- a/drivers/staging/iio/adc/ad7816.c
> > +++ b/drivers/staging/iio/adc/ad7816.c
> > @@ -7,7 +7,7 @@
> >   */
> >  
> >  #include <linux/interrupt.h>
> > -#include <linux/gpio.h>
> > +#include <linux/gpio/consumer.h>
> >  #include <linux/device.h>
> >  #include <linux/kernel.h>
> >  #include <linux/slab.h>
> > @@ -44,9 +44,9 @@
> >  
> >  struct ad7816_chip_info {
> >  	struct spi_device *spi_dev;
> > -	u16 rdwr_pin;
> > -	u16 convert_pin;
> > -	u16 busy_pin;
> > +	struct gpio_desc *rdwr_pin;
> > +	struct gpio_desc *convert_pin;
> > +	struct gpio_desc *busy_pin;
> 
> Only if you want to do a re-spin, here's an idea.
> If you don't want to, feel free to disregard, since your patch is good.
> 
> You could compact things a bit; I know this wasn't what the initial code
> was doing, but it's an option.
> 
> Something like:
> 
> enum {
> 	GPIO_RWDR,
> 	GPIO_CONVERT,
> 	GPIO_BUSY,
> 	__GPIO_MAX,
> }
> 
> Then, what you end up having is:
> 
>  struct ad7816_chip_info {
>   	struct spi_device *spi_dev;
>  -	u16 rdwr_pin;
>  -	u16 convert_pin;
>  -	u16 busy_pin;
>  +	struct gpio_desc *gpios[__GPIO_MAX];
>  
> 
> // Continued below
> 
> 
> >  	u8  oti_data[AD7816_CS_MAX + 1];
> >  	u8  channel_id;	/* 0 always be temperature */
> >  	u8  mode;
> > @@ -61,28 +61,28 @@ static int ad7816_spi_read(struct ad7816_chip_info
> > *chip, u16 *data)
> >  	int ret = 0;
> >  	__be16 buf;
> >  
> > -	gpio_set_value(chip->rdwr_pin, 1);
> > -	gpio_set_value(chip->rdwr_pin, 0);
> > +	gpiod_set_value(chip->rdwr_pin, 1);
> > +	gpiod_set_value(chip->rdwr_pin, 0);
> 
> Obviously, in the above context, this becomes:
>  +	gpiod_set_value(chip->gpios[GPIO_RWDR], 1);
>  +	gpiod_set_value(chip->gpios[GPIO_RWDR], 0);
> 
> >  	ret = spi_write(spi_dev, &chip->channel_id, sizeof(chip-
> > > channel_id));
> > 
> >  	if (ret < 0) {
> >  		dev_err(&spi_dev->dev, "SPI channel setting error\n");
> >  		return ret;
> >  	}
> > -	gpio_set_value(chip->rdwr_pin, 1);
> > +	gpiod_set_value(chip->rdwr_pin, 1);
> >  
> >  	if (chip->mode == AD7816_PD) { /* operating mode 2 */
> > -		gpio_set_value(chip->convert_pin, 1);
> > -		gpio_set_value(chip->convert_pin, 0);
> > +		gpiod_set_value(chip->convert_pin, 1);
> > +		gpiod_set_value(chip->convert_pin, 0);
> >  	} else { /* operating mode 1 */
> > -		gpio_set_value(chip->convert_pin, 0);
> > -		gpio_set_value(chip->convert_pin, 1);
> > +		gpiod_set_value(chip->convert_pin, 0);
> > +		gpiod_set_value(chip->convert_pin, 1);
> >  	}
> >  
> > -	while (gpio_get_value(chip->busy_pin))
> > +	while (gpiod_get_value(chip->busy_pin))
> >  		cpu_relax();
> >  
> > -	gpio_set_value(chip->rdwr_pin, 0);
> > -	gpio_set_value(chip->rdwr_pin, 1);
> > +	gpiod_set_value(chip->rdwr_pin, 0);
> > +	gpiod_set_value(chip->rdwr_pin, 1);
> >  	ret = spi_read(spi_dev, &buf, sizeof(*data));
> >  	if (ret < 0) {
> >  		dev_err(&spi_dev->dev, "SPI data read error\n");
> > @@ -99,8 +99,8 @@ static int ad7816_spi_write(struct ad7816_chip_info
> > *chip, u8 data)
> >  	struct spi_device *spi_dev = chip->spi_dev;
> >  	int ret = 0;
> >  
> > -	gpio_set_value(chip->rdwr_pin, 1);
> > -	gpio_set_value(chip->rdwr_pin, 0);
> > +	gpiod_set_value(chip->rdwr_pin, 1);
> > +	gpiod_set_value(chip->rdwr_pin, 0);
> >  	ret = spi_write(spi_dev, &data, sizeof(data));
> >  	if (ret < 0)
> >  		dev_err(&spi_dev->dev, "SPI oti data write error\n");
> > @@ -129,10 +129,10 @@ static ssize_t ad7816_store_mode(struct device
> > *dev,
> >  	struct ad7816_chip_info *chip = iio_priv(indio_dev);
> >  
> >  	if (strcmp(buf, "full")) {
> > -		gpio_set_value(chip->rdwr_pin, 1);
> > +		gpiod_set_value(chip->rdwr_pin, 1);
> >  		chip->mode = AD7816_FULL;
> >  	} else {
> > -		gpio_set_value(chip->rdwr_pin, 0);
> > +		gpiod_set_value(chip->rdwr_pin, 0);
> >  		chip->mode = AD7816_PD;
> >  	}
> >  
> > @@ -345,15 +345,9 @@ static int ad7816_probe(struct spi_device
> > *spi_dev)
> >  {
> >  	struct ad7816_chip_info *chip;
> >  	struct iio_dev *indio_dev;
> > -	unsigned short *pins = dev_get_platdata(&spi_dev->dev);
> >  	int ret = 0;
> >  	int i;
> >  
> > -	if (!pins) {
> > -		dev_err(&spi_dev->dev, "No necessary GPIO platform
> > data.\n");
> > -		return -EINVAL;
> > -	}
> > -
> >  	indio_dev = devm_iio_device_alloc(&spi_dev->dev, sizeof(*chip));
> >  	if (!indio_dev)
> >  		return -ENOMEM;
> > @@ -364,34 +358,28 @@ static int ad7816_probe(struct spi_device
> > *spi_dev)
> >  	chip->spi_dev = spi_dev;
> >  	for (i = 0; i <= AD7816_CS_MAX; i++)
> >  		chip->oti_data[i] = 203;
> > -	chip->rdwr_pin = pins[0];
> > -	chip->convert_pin = pins[1];
> > -	chip->busy_pin = pins[2];
> > -
> > -	ret = devm_gpio_request(&spi_dev->dev, chip->rdwr_pin,
> > -				spi_get_device_id(spi_dev)->name);
> > -	if (ret) {
> > -		dev_err(&spi_dev->dev, "Fail to request rdwr gpio PIN
> > %d.\n",
> > -			chip->rdwr_pin);
> > +
> > +	chip->rdwr_pin = devm_gpiod_get(&spi_dev->dev, "rdwr", GPIOD_IN);
> > +	if (IS_ERR(chip->rdwr_pin)) {
> > +		ret = PTR_ERR(chip->rdwr_pin);
> > +		dev_err(&spi_dev->dev, "Failed to request rdwr GPIO: %d\n",
> > +			ret);
> >  		return ret;
> >  	}
> 
> But the real benefit if this approach comes here.
> You could do:
> 
> static const char *gpio_names[__GPIO_MAX] = {
> 	[GPIO_RWDR] = "rwdr",
> 	[GPIO_CONVERT] = "convert",
> 	[GPIO_BUSY] = "busy",
> };
> 
> // code for patch2	
> bool have_busy_pin = (chip->id == ID_AD7816 || chip->id == ID_AD7817);
> // end code for patch2	
> 
> 
> for (i = 0; i < __GPIO_MAX; i++) {
> // code for patch2	
> 	if (i == GPIO_BUSY && !have_busy_pin)
> 		continue;
> // end code for patch2	
> 
> 	chip->gpios[i] = devm_gpiod_get(&spi_dev->dev, gpio_names[i], 
> 					GPIOD_IN);
> 	if (IS_ERR(chip->gpios[i])) {
> 		ret = PTR_ERR(chip->gpios[i]);
> 		dev_err(&spi_dev->dev, "Failed to request rdwr GPIO: %d\n",
> 			ret;
> 		return ret;
> 	}
> }
> 
> Then, in your patch2 (i.e " staging: iio: ad7816: Do not use busy_pin in
> case of AD7818"), what you could do, is to add that code (along with the
> other ID code).
> 
> And finaly what you could do in patch2, is:
> 
> 	while (chip->gpios[GPIO_BUSY] &&
> 	       gpiod_get_value(chip->busy_pin))
> 		cpu_relax();
> 
> 
> 
> > -	gpio_direction_input(chip->rdwr_pin);
> > -	ret = devm_gpio_request(&spi_dev->dev, chip->convert_pin,
> > -				spi_get_device_id(spi_dev)->name);
> > -	if (ret) {
> > -		dev_err(&spi_dev->dev, "Fail to request convert gpio PIN
> > %d.\n",
> > -			chip->convert_pin);
> > +	chip->convert_pin = devm_gpiod_get(&spi_dev->dev, "convert",
> > GPIOD_IN);
> > +	if (IS_ERR(chip->convert_pin)) {
> > +		ret = PTR_ERR(chip->convert_pin);
> > +		dev_err(&spi_dev->dev, "Failed to request convert GPIO:
> > %d\n",
> > +			ret);
> >  		return ret;
> >  	}
> > -	gpio_direction_input(chip->convert_pin);
> > -	ret = devm_gpio_request(&spi_dev->dev, chip->busy_pin,
> > -				spi_get_device_id(spi_dev)->name);
> > -	if (ret) {
> > -		dev_err(&spi_dev->dev, "Fail to request busy gpio PIN
> > %d.\n",
> > -			chip->busy_pin);
> > +	chip->busy_pin = devm_gpiod_get(&spi_dev->dev, "busy", GPIOD_IN);
> > +	if (IS_ERR(chip->busy_pin)) {
> > +		ret = PTR_ERR(chip->busy_pin);
> > +		dev_err(&spi_dev->dev, "Failed to request busy GPIO: %d\n",
> > +			ret);
> >  		return ret;
> >  	}
> > -	gpio_direction_input(chip->busy_pin);
> >  
> >  	indio_dev->name = spi_get_device_id(spi_dev)->name;
> >  	indio_dev->dev.parent = &spi_dev->dev;