diff options
Diffstat (limited to 'drivers/iio/adc/ad4695.c')
| -rw-r--r-- | drivers/iio/adc/ad4695.c | 34 |
1 files changed, 28 insertions, 6 deletions
diff --git a/drivers/iio/adc/ad4695.c b/drivers/iio/adc/ad4695.c index b79d135a5471..22fdc454b0ce 100644 --- a/drivers/iio/adc/ad4695.c +++ b/drivers/iio/adc/ad4695.c @@ -92,6 +92,8 @@ #define AD4695_T_REFBUF_MS 100 #define AD4695_T_REGCONFIG_NS 20 #define AD4695_T_SCK_CNV_DELAY_NS 80 +#define AD4695_T_CNVL_NS 80 +#define AD4695_T_CNVH_NS 10 #define AD4695_REG_ACCESS_SCLK_HZ (10 * MEGA) /* Max number of voltage input channels. */ @@ -364,11 +366,31 @@ static int ad4695_enter_advanced_sequencer_mode(struct ad4695_state *st, u32 n) */ static int ad4695_exit_conversion_mode(struct ad4695_state *st) { - struct spi_transfer xfer = { - .tx_buf = &st->cnv_cmd2, - .len = 1, - .delay.value = AD4695_T_REGCONFIG_NS, - .delay.unit = SPI_DELAY_UNIT_NSECS, + /* + * An extra transfer is needed to trigger a conversion here so + * that we can be 100% sure the command will be processed by the + * ADC, rather than relying on it to be in the correct state + * when this function is called (this chip has a quirk where the + * command only works when reading a conversion, and if the + * previous conversion was already read then it won't work). The + * actual conversion command is then run at the slower + * AD4695_REG_ACCESS_SCLK_HZ speed to guarantee this works. + */ + struct spi_transfer xfers[] = { + { + .delay.value = AD4695_T_CNVL_NS, + .delay.unit = SPI_DELAY_UNIT_NSECS, + .cs_change = 1, + .cs_change_delay.value = AD4695_T_CNVH_NS, + .cs_change_delay.unit = SPI_DELAY_UNIT_NSECS, + }, + { + .speed_hz = AD4695_REG_ACCESS_SCLK_HZ, + .tx_buf = &st->cnv_cmd2, + .len = 1, + .delay.value = AD4695_T_REGCONFIG_NS, + .delay.unit = SPI_DELAY_UNIT_NSECS, + }, }; /* @@ -377,7 +399,7 @@ static int ad4695_exit_conversion_mode(struct ad4695_state *st) */ st->cnv_cmd2 = AD4695_CMD_EXIT_CNV_MODE << 3; - return spi_sync_transfer(st->spi, &xfer, 1); + return spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers)); } static int ad4695_set_ref_voltage(struct ad4695_state *st, int vref_mv) |