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Message-ID: <c5890aee-78ac-45a7-b910-72a342f329b1@baylibre.com>
Date: Tue, 7 Jan 2025 17:48:04 -0600
From: David Lechner <dlechner@...libre.com>
To: Jonathan Santos <Jonathan.Santos@...log.com>, linux-iio@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Sergiu Cuciurean <sergiu.cuciurean@...log.com>, lars@...afoo.de,
Michael.Hennerich@...log.com, jic23@...nel.org, robh@...nel.org,
krzk+dt@...nel.org, conor+dt@...nel.org, marcelo.schmitt1@...il.com
Subject: Re: [PATCH v1 12/15] iio: adc: ad7768-1: Add GPIO controller support
On 1/7/25 9:26 AM, Jonathan Santos wrote:
> From: Sergiu Cuciurean <sergiu.cuciurean@...log.com>
>
> The AD7768-1 has the ability to control other local hardware (such as gain
> stages),to power down other blocks in the signal chain, or read local
> status signals over the SPI interface.
>
> This change exports the AD7768-1's four gpios and makes them accessible
> at an upper layer.
We will also need a dt-bindings patch to add gpio-controller and #gpio-cells
properties.
>
> Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@...log.com>
> ---
> drivers/iio/adc/ad7768-1.c | 121 +++++++++++++++++++++++++++++++++++++
> 1 file changed, 121 insertions(+)
>
> diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
> index 675af9ea856d..9741a6d47942 100644
> --- a/drivers/iio/adc/ad7768-1.c
> +++ b/drivers/iio/adc/ad7768-1.c
> @@ -10,6 +10,8 @@
> #include <linux/delay.h>
> #include <linux/device.h>
> #include <linux/err.h>
> +#include <linux/gpio.h>
> +#include <linux/gpio/driver.h>
> #include <linux/gpio/consumer.h>
> #include <linux/kernel.h>
> #include <linux/module.h>
> @@ -77,6 +79,19 @@
> #define AD7768_CONV_MODE_MSK GENMASK(2, 0)
> #define AD7768_CONV_MODE(x) FIELD_PREP(AD7768_CONV_MODE_MSK, x)
>
> +/* AD7768_REG_GPIO_CONTROL */
> +#define AD7768_GPIO_CONTROL_MSK GENMASK(3, 0)
> +#define AD7768_GPIO_UNIVERSAL_EN BIT(7)
Bits should be ordered highest to lowest (from top to bottom) to be consistent
with other code.
> +
> +/* AD7768_REG_GPIO_WRITE */
> +#define AD7768_GPIO_WRITE_MSK GENMASK(3, 0)
> +
> +/* AD7768_REG_GPIO_READ */
> +#define AD7768_GPIO_READ_MSK GENMASK(3, 0)
> +
> +#define AD7768_GPIO_INPUT(x) 0x00
> +#define AD7768_GPIO_OUTPUT(x) BIT(x)
> +
> #define AD7768_RD_FLAG_MSK(x) (BIT(6) | ((x) & 0x3F))
> #define AD7768_WR_FLAG_MSK(x) ((x) & 0x3F)
>
> @@ -190,6 +205,8 @@ struct ad7768_state {
> struct regulator *vref;
> struct mutex lock;
> struct clk *mclk;
> + struct gpio_chip gpiochip;
> + unsigned int gpio_avail_map;
> unsigned int mclk_freq;
> unsigned int samp_freq;
> unsigned int common_mode_voltage;
> @@ -338,6 +355,106 @@ static int ad7768_set_dig_fil(struct ad7768_state *st,
> return 0;
> }
>
> +static int ad7768_gpio_direction_input(struct gpio_chip *chip, unsigned int offset)
> +{
> + struct ad7768_state *st = gpiochip_get_data(chip);
> +
> + guard(mutex)(&st->lock);
As mentioned in another patch, this should be iio_device_claim_direct_mode()
instead of st->lock since we can't access registers during a buffered read
because the chip is in conversion mode. Same applies to other functions below.
> + return ad7768_spi_reg_write_masked(st,
> + AD7768_REG_GPIO_CONTROL,
> + BIT(offset),
> + AD7768_GPIO_INPUT(offset));
> +}
> +
> +static int ad7768_gpio_direction_output(struct gpio_chip *chip,
> + unsigned int offset, int value)
> +{
> + struct ad7768_state *st = gpiochip_get_data(chip);
> +
> + guard(mutex)(&st->lock);
> + return ad7768_spi_reg_write_masked(st,
> + AD7768_REG_GPIO_CONTROL,
> + BIT(offset),
> + AD7768_GPIO_OUTPUT(offset));
> +}
> +
> +static int ad7768_gpio_get(struct gpio_chip *chip, unsigned int offset)
> +{
> + struct ad7768_state *st = gpiochip_get_data(chip);
> + unsigned int val;
> + int ret;
> +
> + guard(mutex)(&st->lock);
> + ret = ad7768_spi_reg_read(st, AD7768_REG_GPIO_CONTROL, &val, 1);
> + if (ret < 0)
> + return ret;
> +
> + if (val & BIT(offset))
> + ret = ad7768_spi_reg_read(st, AD7768_REG_GPIO_WRITE, &val, 1);
> + else
> + ret = ad7768_spi_reg_read(st, AD7768_REG_GPIO_READ, &val, 1);
It doesn't work to just always read AD7768_REG_GPIO_READ?
> + if (ret < 0)
> + return ret;
> +
> + return !!(val & BIT(offset));
> +}
> +
> +static void ad7768_gpio_set(struct gpio_chip *chip, unsigned int offset, int value)
> +{
> + struct ad7768_state *st = gpiochip_get_data(chip);
> + unsigned int val;
> + int ret;
> +
> + guard(mutex)(&st->lock);
> + ret = ad7768_spi_reg_read(st, AD7768_REG_GPIO_CONTROL, &val, 1);
> + if (ret < 0)
> + return;
> +
> + if (val & BIT(offset))
> + ad7768_spi_reg_write_masked(st,
> + AD7768_REG_GPIO_WRITE,
> + BIT(offset),
> + (value << offset));
> +}
> +
> +static int ad7768_gpio_request(struct gpio_chip *chip, unsigned int offset)
> +{
> + struct ad7768_state *st = gpiochip_get_data(chip);
> +
> + if (!(st->gpio_avail_map & BIT(offset)))
> + return -ENODEV;
> +
> + st->gpio_avail_map &= ~BIT(offset);
> +
> + return 0;
> +}
> +
> +static int ad7768_gpio_init(struct ad7768_state *st)
> +{
> + int ret;
> +
> + ret = ad7768_spi_reg_write(st,
> + AD7768_REG_GPIO_CONTROL,
nit: this can fit on the previous line
> + AD7768_GPIO_UNIVERSAL_EN);
> + if (ret < 0)
> + return ret;
> +
> + st->gpio_avail_map = AD7768_GPIO_CONTROL_MSK;
> + st->gpiochip.label = "ad7768_1_gpios";
> + st->gpiochip.base = -1;
> + st->gpiochip.ngpio = 4;
> + st->gpiochip.parent = &st->spi->dev;
> + st->gpiochip.can_sleep = true;
> + st->gpiochip.direction_input = ad7768_gpio_direction_input;
> + st->gpiochip.direction_output = ad7768_gpio_direction_output;
> + st->gpiochip.get = ad7768_gpio_get;
> + st->gpiochip.set = ad7768_gpio_set;
> + st->gpiochip.request = ad7768_gpio_request;
> + st->gpiochip.owner = THIS_MODULE;
> +
> + return gpiochip_add_data(&st->gpiochip, st);
> +}
> +
> static int ad7768_set_freq(struct ad7768_state *st,
> unsigned int freq)
> {
> @@ -538,6 +655,10 @@ static int ad7768_setup(struct ad7768_state *st)
> if (IS_ERR(st->gpio_sync_in))
> return PTR_ERR(st->gpio_sync_in);
>
Since the GPIO pins can also be wired up as mode input pins, this should not be
always enabled. We can use the `gpio-controller` DT property as a flag to
conditionally enable GPIO support when it is actually wired up for that purpose.
> + ret = ad7768_gpio_init(st);
> + if (ret < 0)
> + return ret;
> +
> /* Set the default sampling frequency to 32000 kSPS */
> return ad7768_set_freq(st, 32000);
> }
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