linux-kernel - Re: [PATCH 2/6] iio: imu: adis16480: Add support for configurable drdy indicator

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Message-ID: <20190220102945.6af3edc4@archlinux>
Date:   Wed, 20 Feb 2019 10:29:45 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Stefan Popa <stefan.popa@...log.com>
Cc:     <robh+dt@...nel.org>, <Michael.Hennerich@...log.com>,
        <knaack.h@....de>, <lars@...afoo.de>, <pmeerw@...erw.net>,
        <gregkh@...uxfoundation.org>, <linux-kernel@...r.kernel.org>,
        <linux-iio@...r.kernel.org>
Subject: Re: [PATCH 2/6] iio: imu: adis16480: Add support for configurable
 drdy indicator

On Tue, 19 Feb 2019 19:12:14 +0200
Stefan Popa <stefan.popa@...log.com> wrote:

> The FNCTIO_CTRL register provides configuration control for each I/O pin
> (DIO1, DIO2, DIO3 and DIO4).
> 
> This patch adds the option to configure each DIOx pin as data ready
> indicator with positive or negative polarity by reading the 'interrupts'
> and 'interrupt-names' properties from the devicetree. The
> 'interrupt-names' property is optional, if it is not specified, then the
> factory default DIO2 data ready signal is used.
> 
> Signed-off-by: Stefan Popa <stefan.popa@...log.com>
Other than follow on from the previous patch change of the default, this
looks fine to me.

One question inline.

Jonathan
> ---
>  drivers/iio/imu/adis16480.c | 76 +++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 76 insertions(+)
> 
> diff --git a/drivers/iio/imu/adis16480.c b/drivers/iio/imu/adis16480.c
> index d222188..38ba0c1 100644
> --- a/drivers/iio/imu/adis16480.c
> +++ b/drivers/iio/imu/adis16480.c
> @@ -10,6 +10,7 @@
>   */
>  
>  #include <linux/bitfield.h>
> +#include <linux/of_irq.h>
>  #include <linux/interrupt.h>
>  #include <linux/delay.h>
>  #include <linux/mutex.h>
> @@ -109,6 +110,10 @@
>  #define ADIS16480_FIR_COEF_D(x)			ADIS16480_FIR_COEF(0x0B, (x))
>  
>  /* ADIS16480_REG_FNCTIO_CTRL */
> +#define ADIS16480_DRDY_SEL_MSK		GENMASK(1, 0)
> +#define ADIS16480_DRDY_SEL(x)		FIELD_PREP(ADIS16480_DRDY_SEL_MSK, x)
> +#define ADIS16480_DRDY_POL_MSK		BIT(2)
> +#define ADIS16480_DRDY_POL(x)		FIELD_PREP(ADIS16480_DRDY_POL_MSK, x)
>  #define ADIS16480_DRDY_EN_MSK		BIT(3)
>  #define ADIS16480_DRDY_EN(x)		FIELD_PREP(ADIS16480_DRDY_EN_MSK, x)
>  
> @@ -121,12 +126,26 @@ struct adis16480_chip_info {
>  	unsigned int accel_max_scale;
>  };
>  
> +enum adis16480_int_pin {
> +	ADIS16480_PIN_DIO1,
> +	ADIS16480_PIN_DIO2,
> +	ADIS16480_PIN_DIO3,
> +	ADIS16480_PIN_DIO4
> +};
> +
>  struct adis16480 {
>  	const struct adis16480_chip_info *chip_info;
>  
>  	struct adis adis;
>  };
>  
> +static const char * const adis16480_int_pin_names[4] = {
> +	[ADIS16480_PIN_DIO1] = "DIO1",
> +	[ADIS16480_PIN_DIO2] = "DIO2",
> +	[ADIS16480_PIN_DIO3] = "DIO3",
> +	[ADIS16480_PIN_DIO4] = "DIO4",
> +};
> +
>  #ifdef CONFIG_DEBUG_FS
>  
>  static ssize_t adis16480_show_firmware_revision(struct file *file,
> @@ -840,6 +859,59 @@ static const struct adis_data adis16480_data = {
>  	.enable_irq = adis16480_enable_irq,
>  };
>  
> +static int adis16480_config_irq_pin(struct device_node *of_node,
> +				    struct adis16480 *st)
> +{
> +	struct irq_data *desc;
> +	enum adis16480_int_pin pin;
> +	unsigned int irq_type;
> +	uint16_t val;
> +	int i, irq = 0;
> +
> +	desc = irq_get_irq_data(st->adis.spi->irq);
> +	if (!desc) {
> +		dev_err(&st->adis.spi->dev, "Could not find IRQ %d\n", irq);
> +		return -EINVAL;
> +	}
> +
> +	/* Disable data ready */
> +	val = ADIS16480_DRDY_EN(0);
Does it default to on after reset?
That's a little unusual and nasty.  If not, why are you disabling here?
> +
> +	/*
> +	 * Get the interrupt from the devicetre by reading the
> +	 * interrupt-names property. If it is not specified, use
> +	 * the default interrupt on DIO2 pin.
> +	 */
> +	pin = ADIS16480_PIN_DIO2;
> +	for (i = 0; i < ARRAY_SIZE(adis16480_int_pin_names); i++) {
> +		irq = of_irq_get_byname(of_node, adis16480_int_pin_names[i]);
> +		if (irq > 0) {
> +			pin = i;
> +			break;
> +		}
> +	}
> +
> +	val |= ADIS16480_DRDY_SEL(pin);
> +
> +	/*
> +	 * Get the interrupt line behaviour. The data ready polarity can be
> +	 * configured as positive or negative, corresponding to
> +	 * IRQF_TRIGGER_RISING or IRQF_TRIGGER_FALLING respectively.
> +	 */
> +	irq_type = irqd_get_trigger_type(desc);
> +	if (irq_type == IRQF_TRIGGER_RISING) { /* Default */
> +		val |= ADIS16480_DRDY_POL(1);
> +	} else if (irq_type == IRQF_TRIGGER_FALLING) {
> +		val |= ADIS16480_DRDY_POL(0);
> +	} else {
> +		dev_err(&st->adis.spi->dev,
> +			"Invalid interrupt type 0x%x specified\n", irq_type);
> +		return -EINVAL;
> +	}
> +	/* Write the data ready configuration to the FNCTIO_CTRL register */
> +	return adis_write_reg_16(&st->adis, ADIS16480_REG_FNCTIO_CTRL, val);
> +}
> +
>  static int adis16480_probe(struct spi_device *spi)
>  {
>  	const struct spi_device_id *id = spi_get_device_id(spi);
> @@ -867,6 +939,10 @@ static int adis16480_probe(struct spi_device *spi)
>  	if (ret)
>  		return ret;
>  
> +	ret =  adis16480_config_irq_pin(spi->dev.of_node, st);
> +	if (ret)
> +		return ret;
> +
>  	ret = adis_setup_buffer_and_trigger(&st->adis, indio_dev, NULL);
>  	if (ret)
>  		return ret;