Re: [PATCH 02/10] iio: imu: adis: add unlocked read/write function versions

[Jonathan Cameron]

On Thu, 26 Sep 2019 14:18:04 +0300
Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx> wrote:

> This will allow more flexible control to group reads & writes into a single
> lock (particularly the state_lock).
> 
> The end-goal is to remove the indio_dev->mlock usage, and the simplest fix
> would have been to just add another lock, which would not be a good idea on
> the long-run.
> 
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx>
Applied to the togreg branch of iio.git and pushed out as testing etc.

Jonathan

> ---
>  drivers/iio/imu/adis.c       |  34 +++++------
>  include/linux/iio/imu/adis.h | 114 ++++++++++++++++++++++++++++++++++-
>  2 files changed, 128 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/iio/imu/adis.c b/drivers/iio/imu/adis.c
> index 3c2d896e3a96..4f3be011c898 100644
> --- a/drivers/iio/imu/adis.c
> +++ b/drivers/iio/imu/adis.c
> @@ -26,7 +26,14 @@
>  #define ADIS_MSC_CTRL_DATA_RDY_DIO2	BIT(0)
>  #define ADIS_GLOB_CMD_SW_RESET		BIT(7)
>  
> -int adis_write_reg(struct adis *adis, unsigned int reg,
> +/**
> + * __adis_write_reg() - write N bytes to register (unlocked version)
> + * @adis: The adis device
> + * @reg: The address of the lower of the two registers
> + * @value: The value to write to device (up to 4 bytes)
> + * @size: The size of the @value (in bytes)
> + */
> +int __adis_write_reg(struct adis *adis, unsigned int reg,
>  	unsigned int value, unsigned int size)
>  {
>  	unsigned int page = reg / ADIS_PAGE_SIZE;
> @@ -70,8 +77,6 @@ int adis_write_reg(struct adis *adis, unsigned int reg,
>  		},
>  	};
>  
> -	mutex_lock(&adis->state_lock);
> -
>  	spi_message_init(&msg);
>  
>  	if (adis->current_page != page) {
> @@ -96,8 +101,7 @@ int adis_write_reg(struct adis *adis, unsigned int reg,
>  		adis->tx[3] = value & 0xff;
>  		break;
>  	default:
> -		ret = -EINVAL;
> -		goto out_unlock;
> +		return -EINVAL;
>  	}
>  
>  	xfers[size].cs_change = 0;
> @@ -113,20 +117,18 @@ int adis_write_reg(struct adis *adis, unsigned int reg,
>  		adis->current_page = page;
>  	}
>  
> -out_unlock:
> -	mutex_unlock(&adis->state_lock);
> -
>  	return ret;
>  }
> -EXPORT_SYMBOL_GPL(adis_write_reg);
> +EXPORT_SYMBOL_GPL(__adis_write_reg);
>  
>  /**
> - * adis_read_reg() - read 2 bytes from a 16-bit register
> + * __adis_read_reg() - read N bytes from register (unlocked version)
>   * @adis: The adis device
>   * @reg: The address of the lower of the two registers
>   * @val: The value read back from the device
> + * @size: The size of the @val buffer
>   */
> -int adis_read_reg(struct adis *adis, unsigned int reg,
> +int __adis_read_reg(struct adis *adis, unsigned int reg,
>  	unsigned int *val, unsigned int size)
>  {
>  	unsigned int page = reg / ADIS_PAGE_SIZE;
> @@ -188,15 +190,14 @@ int adis_read_reg(struct adis *adis, unsigned int reg,
>  		spi_message_add_tail(&xfers[3], &msg);
>  		break;
>  	default:
> -		ret = -EINVAL;
> -		goto out_unlock;
> +		return -EINVAL;
>  	}
>  
>  	ret = spi_sync(adis->spi, &msg);
>  	if (ret) {
>  		dev_err(&adis->spi->dev, "Failed to read register 0x%02X: %d\n",
>  				reg, ret);
> -		goto out_unlock;
> +		return ret;
>  	} else {
>  		adis->current_page = page;
>  	}
> @@ -210,12 +211,9 @@ int adis_read_reg(struct adis *adis, unsigned int reg,
>  		break;
>  	}
>  
> -out_unlock:
> -	mutex_unlock(&adis->state_lock);
> -
>  	return ret;
>  }
> -EXPORT_SYMBOL_GPL(adis_read_reg);
> +EXPORT_SYMBOL_GPL(__adis_read_reg);
>  
>  #ifdef CONFIG_DEBUG_FS
>  
> diff --git a/include/linux/iio/imu/adis.h b/include/linux/iio/imu/adis.h
> index 3ed5eceaac2d..3a028c40e04e 100644
> --- a/include/linux/iio/imu/adis.h
> +++ b/include/linux/iio/imu/adis.h
> @@ -75,11 +75,121 @@ int adis_init(struct adis *adis, struct iio_dev *indio_dev,
>  	struct spi_device *spi, const struct adis_data *data);
>  int adis_reset(struct adis *adis);
>  
> -int adis_write_reg(struct adis *adis, unsigned int reg,
> +int __adis_write_reg(struct adis *adis, unsigned int reg,
>  	unsigned int val, unsigned int size);
> -int adis_read_reg(struct adis *adis, unsigned int reg,
> +int __adis_read_reg(struct adis *adis, unsigned int reg,
>  	unsigned int *val, unsigned int size);
>  
> +/**
> + * __adis_write_reg_8() - Write single byte to a register (unlocked version)
> + * @adis: The adis device
> + * @reg: The address of the register to be written
> + * @value: The value to write
> + */
> +static inline int __adis_write_reg_8(struct adis *adis, unsigned int reg,
> +	uint8_t val)
> +{
> +	return __adis_write_reg(adis, reg, val, 1);
> +}
> +
> +/**
> + * __adis_write_reg_16() - Write 2 bytes to a pair of registers (unlocked version)
> + * @adis: The adis device
> + * @reg: The address of the lower of the two registers
> + * @value: Value to be written
> + */
> +static inline int __adis_write_reg_16(struct adis *adis, unsigned int reg,
> +	uint16_t val)
> +{
> +	return __adis_write_reg(adis, reg, val, 2);
> +}
> +
> +/**
> + * __adis_write_reg_32() - write 4 bytes to four registers (unlocked version)
> + * @adis: The adis device
> + * @reg: The address of the lower of the four register
> + * @value: Value to be written
> + */
> +static inline int __adis_write_reg_32(struct adis *adis, unsigned int reg,
> +	uint32_t val)
> +{
> +	return __adis_write_reg(adis, reg, val, 4);
> +}
> +
> +/**
> + * __adis_read_reg_16() - read 2 bytes from a 16-bit register (unlocked version)
> + * @adis: The adis device
> + * @reg: The address of the lower of the two registers
> + * @val: The value read back from the device
> + */
> +static inline int __adis_read_reg_16(struct adis *adis, unsigned int reg,
> +	uint16_t *val)
> +{
> +	unsigned int tmp;
> +	int ret;
> +
> +	ret = __adis_read_reg(adis, reg, &tmp, 2);
> +	*val = tmp;
> +
> +	return ret;
> +}
> +
> +/**
> + * __adis_read_reg_32() - read 4 bytes from a 32-bit register (unlocked version)
> + * @adis: The adis device
> + * @reg: The address of the lower of the two registers
> + * @val: The value read back from the device
> + */
> +static inline int __adis_read_reg_32(struct adis *adis, unsigned int reg,
> +	uint32_t *val)
> +{
> +	unsigned int tmp;
> +	int ret;
> +
> +	ret = __adis_read_reg(adis, reg, &tmp, 4);
> +	*val = tmp;
> +
> +	return ret;
> +}
> +
> +/**
> + * adis_write_reg() - write N bytes to register
> + * @adis: The adis device
> + * @reg: The address of the lower of the two registers
> + * @value: The value to write to device (up to 4 bytes)
> + * @size: The size of the @value (in bytes)
> + */
> +static inline int adis_write_reg(struct adis *adis, unsigned int reg,
> +	unsigned int val, unsigned int size)
> +{
> +	int ret;
> +
> +	mutex_lock(&adis->state_lock);
> +	ret = __adis_write_reg(adis, reg, val, size);
> +	mutex_unlock(&adis->state_lock);
> +
> +	return ret;
> +}
> +
> +/**
> + * adis_read_reg() - read N bytes from register
> + * @adis: The adis device
> + * @reg: The address of the lower of the two registers
> + * @val: The value read back from the device
> + * @size: The size of the @val buffer
> + */
> +static int adis_read_reg(struct adis *adis, unsigned int reg,
> +	unsigned int *val, unsigned int size)
> +{
> +	int ret;
> +
> +	mutex_lock(&adis->state_lock);
> +	ret = __adis_read_reg(adis, reg, val, size);
> +	mutex_unlock(&adis->state_lock);
> +
> +	return ret;
> +}
> +
>  /**
>   * adis_write_reg_8() - Write single byte to a register
>   * @adis: The adis device