From: Robert Hancock robert.hancock@calian.com
commit 0bf126163c3e7e6d722622073046aed567a5551e upstream.
Some of the AMS channels need to be read by switching into single-channel mode from the normal polling sequence. There was a logic issue in this switching code that could cause the first read of these channels to read back as zero.
It appears that the sequencer should be set back to default mode before changing the channel selection, and the channel should be set before switching the sequencer back into single-channel mode.
Also, write 1 to the EOC bit in the status register to clear it before waiting for it to become set, so that we actually wait for a new conversion to complete, and don't proceed based on a previous conversion completing.
Fixes: d5c70627a794 ("iio: adc: Add Xilinx AMS driver") Signed-off-by: Robert Hancock robert.hancock@calian.com Acked-by: Michal Simek michal.simek@xilinx.com Link: https://lore.kernel.org/r/20220127173450.3684318-5-robert.hancock@calian.com Cc: Stable@vger.kernel.org Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/iio/adc/xilinx-ams.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
--- a/drivers/iio/adc/xilinx-ams.c +++ b/drivers/iio/adc/xilinx-ams.c @@ -530,14 +530,18 @@ static int ams_enable_single_channel(str return -EINVAL; }
- /* set single channel, sequencer off mode */ + /* put sysmon in a soft reset to change the sequence */ ams_ps_update_reg(ams, AMS_REG_CONFIG1, AMS_CONF1_SEQ_MASK, - AMS_CONF1_SEQ_SINGLE_CHANNEL); + AMS_CONF1_SEQ_DEFAULT);
/* write the channel number */ ams_ps_update_reg(ams, AMS_REG_CONFIG0, AMS_CONF0_CHANNEL_NUM_MASK, channel_num);
+ /* set single channel, sequencer off mode */ + ams_ps_update_reg(ams, AMS_REG_CONFIG1, AMS_CONF1_SEQ_MASK, + AMS_CONF1_SEQ_SINGLE_CHANNEL); + return 0; }
@@ -551,6 +555,8 @@ static int ams_read_vcc_reg(struct ams * if (ret) return ret;
+ /* clear end-of-conversion flag, wait for next conversion to complete */ + writel(expect, ams->base + AMS_ISR_1); ret = readl_poll_timeout(ams->base + AMS_ISR_1, reg, (reg & expect), AMS_INIT_POLL_TIME_US, AMS_INIT_TIMEOUT_US); if (ret)