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authorLars-Peter Clausen <lars@metafoo.de>2013-11-25 16:41:00 +0400
committerJonathan Cameron <jic23@kernel.org>2013-12-04 00:22:25 +0400
commit0dbe59c7a78811144cd1860c5bc603eb6b536cfb (patch)
treee4c465a207770729df3e11fb8cd76b4c813e59aa /drivers/iio/dac
parent61c358e3bc20abeab2ba2ae9625ca723409b6766 (diff)
downloadlinux-0dbe59c7a78811144cd1860c5bc603eb6b536cfb.tar.xz
iio:ad5504: Do not store transfer buffers on the stack
Some SPI controllers may not be able to handle transfer buffers that are placed on the stack. Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Diffstat (limited to 'drivers/iio/dac')
-rw-r--r--drivers/iio/dac/ad5504.c40
1 files changed, 20 insertions, 20 deletions
diff --git a/drivers/iio/dac/ad5504.c b/drivers/iio/dac/ad5504.c
index 6cd0dd60c17f..d44c8f5fadee 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;
}