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Message-ID: <3c8e9f9ced57c33dc7182cae91d6f72e0fdb6c58.camel@analog.com>
Date: Fri, 9 Nov 2018 08:08:24 +0000
From: "Ardelean, Alexandru" <alexandru.Ardelean@...log.com>
To: "lars@...afoo.de" <lars@...afoo.de>,
"nishadkamdar@...il.com" <nishadkamdar@...il.com>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"knaack.h@....de" <knaack.h@....de>,
"jic23@...nel.org" <jic23@...nel.org>,
"Hennerich, Michael" <Michael.Hennerich@...log.com>,
"linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
"devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
"pmeerw@...erw.net" <pmeerw@...erw.net>,
"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v3 1/4] staging: iio: ad7816: Switch to the gpio
descriptor interface
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@...il.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;
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