Re: [PATCH 4/7] iio:imu:adis: Add paging support

[Jonathan Cameron <jic23@kernel.org>]

On 11/20/2012 01:36 PM, Lars-Peter Clausen wrote:
> Some of the newer generation devices from the ADIS16XXX series have more
> registers than what can be supported with the current register addressing
> scheme. These devices implement register paging to support a larger register
> range. Each page is 128 registers large and the currently active page can be
> selected via register 0x00 in each page. This patch implements transparent
> paging inside the common adis library. The register read/write interface stays
> the same and when a register is accessed the library automatically switches to
> the correct page if it is not already selected. The page number is encoded in
> the upper bits of the register number, e.g. register 0x5 of page 1 is 0x85.
> 
> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
added to togreg branch of iio.git

> ---
>  drivers/iio/imu/adis.c        | 70 +++++++++++++++++++++++++++++++++----------
>  drivers/iio/imu/adis_buffer.c | 15 ++++++++++
>  include/linux/iio/imu/adis.h  | 10 +++++--
>  3 files changed, 77 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/iio/imu/adis.c b/drivers/iio/imu/adis.c
> index 280a495..c4ea04f 100644
> --- a/drivers/iio/imu/adis.c
> +++ b/drivers/iio/imu/adis.c
> @@ -30,6 +30,7 @@
>  int adis_write_reg(struct adis *adis, unsigned int reg,
>  	unsigned int value, unsigned int size)
>  {
> +	unsigned int page = reg / ADIS_PAGE_SIZE;
>  	int ret, i;
>  	struct spi_message msg;
>  	struct spi_transfer xfers[] = {
> @@ -56,39 +57,53 @@ int adis_write_reg(struct adis *adis, unsigned int reg,
>  			.bits_per_word = 8,
>  			.len = 2,
>  			.delay_usecs = adis->data->write_delay,
> +		}, {
> +			.tx_buf = adis->tx + 8,
> +			.bits_per_word = 8,
> +			.len = 2,
> +			.delay_usecs = adis->data->write_delay,
>  		},
>  	};
>  
>  	mutex_lock(&adis->txrx_lock);
>  
>  	spi_message_init(&msg);
> +
> +	if (adis->current_page != page) {
> +		adis->tx[0] = ADIS_WRITE_REG(ADIS_REG_PAGE_ID);
> +		adis->tx[1] = page;
> +		spi_message_add_tail(&xfers[0], &msg);
> +	}
> +
>  	switch (size) {
>  	case 4:
> -		adis->tx[6] = ADIS_WRITE_REG(reg + 3);
> -		adis->tx[7] = (value >> 24) & 0xff;
> -		adis->tx[4] = ADIS_WRITE_REG(reg + 2);
> -		adis->tx[5] = (value >> 16) & 0xff;
> +		adis->tx[8] = ADIS_WRITE_REG(reg + 3);
> +		adis->tx[9] = (value >> 24) & 0xff;
> +		adis->tx[6] = ADIS_WRITE_REG(reg + 2);
> +		adis->tx[7] = (value >> 16) & 0xff;
>  	case 2:
> -		adis->tx[2] = ADIS_WRITE_REG(reg + 1);
> -		adis->tx[3] = (value >> 8) & 0xff;
> +		adis->tx[4] = ADIS_WRITE_REG(reg + 1);
> +		adis->tx[5] = (value >> 8) & 0xff;
>  	case 1:
> -		adis->tx[0] = ADIS_WRITE_REG(reg);
> -		adis->tx[1] = value & 0xff;
> +		adis->tx[2] = ADIS_WRITE_REG(reg);
> +		adis->tx[3] = value & 0xff;
>  		break;
>  	default:
>  		ret = -EINVAL;
>  		goto out_unlock;
>  	}
>  
> -	xfers[size - 1].cs_change = 0;
> +	xfers[size].cs_change = 0;
>  
> -	for (i = 0; i < size; i++)
> +	for (i = 1; i <= size; i++)
>  		spi_message_add_tail(&xfers[i], &msg);
>  
>  	ret = spi_sync(adis->spi, &msg);
>  	if (ret) {
>  		dev_err(&adis->spi->dev, "Failed to write register 0x%02X: %d\n",
>  				reg, ret);
> +	} else {
> +		adis->current_page = page;
>  	}
>  
>  out_unlock:
> @@ -107,6 +122,7 @@ EXPORT_SYMBOL_GPL(adis_write_reg);
>  int adis_read_reg(struct adis *adis, unsigned int reg,
>  	unsigned int *val, unsigned int size)
>  {
> +	unsigned int page = reg / ADIS_PAGE_SIZE;
>  	struct spi_message msg;
>  	int ret;
>  	struct spi_transfer xfers[] = {
> @@ -115,9 +131,15 @@ int adis_read_reg(struct adis *adis, unsigned int reg,
>  			.bits_per_word = 8,
>  			.len = 2,
>  			.cs_change = 1,
> -			.delay_usecs = adis->data->read_delay,
> +			.delay_usecs = adis->data->write_delay,
>  		}, {
>  			.tx_buf = adis->tx + 2,
> +			.bits_per_word = 8,
> +			.len = 2,
> +			.cs_change = 1,
> +			.delay_usecs = adis->data->read_delay,
> +		}, {
> +			.tx_buf = adis->tx + 4,
>  			.rx_buf = adis->rx,
>  			.bits_per_word = 8,
>  			.len = 2,
> @@ -134,16 +156,22 @@ int adis_read_reg(struct adis *adis, unsigned int reg,
>  	mutex_lock(&adis->txrx_lock);
>  	spi_message_init(&msg);
>  
> +	if (adis->current_page != page) {
> +		adis->tx[0] = ADIS_WRITE_REG(ADIS_REG_PAGE_ID);
> +		adis->tx[1] = page;
> +		spi_message_add_tail(&xfers[0], &msg);
> +	}
> +
>  	switch (size) {
>  	case 4:
> -		adis->tx[0] = ADIS_READ_REG(reg + 2);
> -		adis->tx[1] = 0;
> -		spi_message_add_tail(&xfers[0], &msg);
> -	case 2:
> -		adis->tx[2] = ADIS_READ_REG(reg);
> +		adis->tx[2] = ADIS_READ_REG(reg + 2);
>  		adis->tx[3] = 0;
>  		spi_message_add_tail(&xfers[1], &msg);
> +	case 2:
> +		adis->tx[4] = ADIS_READ_REG(reg);
> +		adis->tx[5] = 0;
>  		spi_message_add_tail(&xfers[2], &msg);
> +		spi_message_add_tail(&xfers[3], &msg);
>  		break;
>  	default:
>  		ret = -EINVAL;
> @@ -155,6 +183,8 @@ int adis_read_reg(struct adis *adis, unsigned int reg,
>  		dev_err(&adis->spi->dev, "Failed to read register 0x%02X: %d\n",
>  				reg, ret);
>  		goto out_unlock;
> +	} else {
> +		adis->current_page = page;
>  	}
>  
>  	switch (size) {
> @@ -390,6 +420,14 @@ int adis_init(struct adis *adis, struct iio_dev *indio_dev,
>  	adis->data = data;
>  	iio_device_set_drvdata(indio_dev, adis);
>  
> +	if (data->has_paging) {
> +		/* Need to set the page before first read/write */
> +		adis->current_page = -1;
> +	} else {
> +		/* Page will always be 0 */
> +		adis->current_page = 0;
> +	}
> +
>  	return adis_enable_irq(adis, false);
>  }
>  EXPORT_SYMBOL_GPL(adis_init);
> diff --git a/drivers/iio/imu/adis_buffer.c b/drivers/iio/imu/adis_buffer.c
> index 7857133..99d8e0b 100644
> --- a/drivers/iio/imu/adis_buffer.c
> +++ b/drivers/iio/imu/adis_buffer.c
> @@ -83,10 +83,25 @@ static irqreturn_t adis_trigger_handler(int irq, void *p)
>  	if (!adis->buffer)
>  		return -ENOMEM;
>  
> +	if (adis->data->has_paging) {
> +		mutex_lock(&adis->txrx_lock);
> +		if (adis->current_page != 0) {
> +			adis->tx[0] = ADIS_WRITE_REG(ADIS_REG_PAGE_ID);
> +			adis->tx[1] = 0;
> +			spi_write(adis->spi, adis->tx, 2);
> +		}
> +	}
> +
>  	ret = spi_sync(adis->spi, &adis->msg);
>  	if (ret)
>  		dev_err(&adis->spi->dev, "Failed to read data: %d", ret);
>  
> +
> +	if (adis->data->has_paging) {
> +		adis->current_page = 0;
> +		mutex_unlock(&adis->txrx_lock);
> +	}
> +
>  	/* Guaranteed to be aligned with 8 byte boundary */
>  	if (indio_dev->scan_timestamp) {
>  		void *b = adis->buffer + indio_dev->scan_bytes - sizeof(s64);
> diff --git a/include/linux/iio/imu/adis.h b/include/linux/iio/imu/adis.h
> index 6402a08..e82cd08 100644
> --- a/include/linux/iio/imu/adis.h
> +++ b/include/linux/iio/imu/adis.h
> @@ -14,8 +14,11 @@
>  #include <linux/interrupt.h>
>  #include <linux/iio/types.h>
>  
> -#define ADIS_WRITE_REG(reg) (0x80 | (reg))
> -#define ADIS_READ_REG(reg) (reg)
> +#define ADIS_WRITE_REG(reg) ((0x80 | (reg)))
> +#define ADIS_READ_REG(reg) ((reg) & 0x7f)
> +
> +#define ADIS_PAGE_SIZE 0x80
> +#define ADIS_REG_PAGE_ID 0x00
>  
>  /**
>   * struct adis_data - ADIS chip variant specific data
> @@ -40,6 +43,8 @@ struct adis_data {
>  
>  	const char * const *status_error_msgs;
>  	unsigned int status_error_mask;
> +
> +	bool has_paging;
>  };
>  
>  struct adis {
> @@ -51,6 +56,7 @@ struct adis {
>  	struct mutex		txrx_lock;
>  	struct spi_message	msg;
>  	struct spi_transfer	*xfer;
> +	unsigned int		current_page;
>  	void			*buffer;
>  
>  	uint8_t			tx[10] ____cacheline_aligned;
>