On 11/25/13 12:41, Lars-Peter Clausen wrote:
> Some SPI controllers may not be able to handle transfer buffers that are placed
> on the stack.
>
> Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
Applied to the togreg branch of iio.git
Thanks
> ---
> drivers/iio/dac/ad5504.c | 40 ++++++++++++++++++++--------------------
> 1 file changed, 20 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/iio/dac/ad5504.c b/drivers/iio/dac/ad5504.c
> index 6cd0dd6..d44c8f5 100644
> --- a/drivers/iio/dac/ad5504.c
> +++ b/drivers/iio/dac/ad5504.c
> @@ -47,14 +47,16 @@
> * @vref_mv: actual reference voltage used
> * @pwr_down_mask power down mask
> * @pwr_down_mode current power down mode
> + * @data: transfer buffer
> */
> -
> struct ad5504_state {
> struct spi_device *spi;
> struct regulator *reg;
> unsigned short vref_mv;
> unsigned pwr_down_mask;
> unsigned pwr_down_mode;
> +
> + __be16 data[2] ____cacheline_aligned;
> };
>
> /**
> @@ -66,31 +68,29 @@ enum ad5504_supported_device_ids {
> ID_AD5501,
> };
>
> -static int ad5504_spi_write(struct spi_device *spi, u8 addr, u16 val)
> +static int ad5504_spi_write(struct ad5504_state *st, u8 addr, u16 val)
> {
> - __be16 tmp = cpu_to_be16(AD5504_CMD_WRITE |
> - AD5504_ADDR(addr) |
> + st->data[0] = cpu_to_be16(AD5504_CMD_WRITE | AD5504_ADDR(addr) |
> (val & AD5504_RES_MASK));
>
> - return spi_write(spi, (u8 *)&tmp, 2);
> + return spi_write(st->spi, &st->data[0], 2);
> }
>
> -static int ad5504_spi_read(struct spi_device *spi, u8 addr)
> +static int ad5504_spi_read(struct ad5504_state *st, u8 addr)
> {
> - __be16 tmp = cpu_to_be16(AD5504_CMD_READ | AD5504_ADDR(addr));
> - __be16 val;
> int ret;
> - struct spi_transfer t = {
> - .tx_buf = &tmp,
> - .rx_buf = &val,
> - .len = 2,
> - };
> - ret = spi_sync_transfer(spi, &t, 1);
> -
> + struct spi_transfer t = {
> + .tx_buf = &st->data[0],
> + .rx_buf = &st->data[1],
> + .len = 2,
> + };
> +
> + st->data[0] = cpu_to_be16(AD5504_CMD_READ | AD5504_ADDR(addr));
> + ret = spi_sync_transfer(st->spi, &t, 1);
> if (ret < 0)
> return ret;
>
> - return be16_to_cpu(val) & AD5504_RES_MASK;
> + return be16_to_cpu(st->data[1]) & AD5504_RES_MASK;
> }
>
> static int ad5504_read_raw(struct iio_dev *indio_dev,
> @@ -104,7 +104,7 @@ static int ad5504_read_raw(struct iio_dev *indio_dev,
>
> switch (m) {
> case IIO_CHAN_INFO_RAW:
> - ret = ad5504_spi_read(st->spi, chan->address);
> + ret = ad5504_spi_read(st, chan->address);
> if (ret < 0)
> return ret;
>
> @@ -133,7 +133,7 @@ static int ad5504_write_raw(struct iio_dev *indio_dev,
> if (val >= (1 << chan->scan_type.realbits) || val < 0)
> return -EINVAL;
>
> - return ad5504_spi_write(st->spi, chan->address, val);
> + return ad5504_spi_write(st, chan->address, val);
> default:
> ret = -EINVAL;
> }
> @@ -197,12 +197,12 @@ static ssize_t ad5504_write_dac_powerdown(struct iio_dev *indio_dev,
> else
> st->pwr_down_mask &= ~(1 << chan->channel);
>
> - ret = ad5504_spi_write(st->spi, AD5504_ADDR_CTRL,
> + ret = ad5504_spi_write(st, AD5504_ADDR_CTRL,
> AD5504_DAC_PWRDWN_MODE(st->pwr_down_mode) |
> AD5504_DAC_PWR(st->pwr_down_mask));
>
> /* writes to the CTRL register must be followed by a NOOP */
> - ad5504_spi_write(st->spi, AD5504_ADDR_NOOP, 0);
> + ad5504_spi_write(st, AD5504_ADDR_NOOP, 0);
>
> return ret ? ret : len;
> }
>
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