Tool/software:
Hi,
I am working with the following setup:
CPU: iMX93
IC: ADS7950
SPI: LPSPI7 chip select on GPIO2 4
OS: Yocto Linux based on kernel version L6.1.22
I'm getting I/O error while trying to read ADC channel values in sysfs.
Below is the relevant device tree configuration:
lpspi7: spi@42710000 {
#address-cells = <1>;
#size-cells = <0>;
compatible = "fsl,imx93-spi", "fsl,imx7ulp-spi";
reg = <0x42710000 0x10000>;
interrupts = <GIC_SPI 193 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&clk IMX93_CLK_LPSPI7_GATE>,
<&clk IMX93_CLK_BUS_WAKEUP>;
clock-names = "per", "ipg";
};
&lpspi7 {
fsl,spi-num-chipselects = <1>;
pinctrl-names = "default", "sleep";
pinctrl-0 = <&pinctrl_lpspi7>, <&pinctrl_lpspi7_cs>;
pinctrl-1 = <&pinctrl_lpspi7>, <&pinctrl_lpspi7_cs>;
cs-gpios = <&gpio2 4 GPIO_ACTIVE_LOW>;
dmas = <&edma2 83 0 0>, <&edma2 84 0 1>;
dma-names = "tx","rx";
assigned-clock-rates = <30000000>;
status = "okay";
adc@0 {
compatible = "ti,ads7950";
reg = <0>; /* SPI chip select 0 */
vref-supply = <®_5v>;
spi-max-frequency = <10000000>;
#io-channel-cells = <1>;
status = "okay";
};
};
pinctrl_lpspi7: lpspi7grp { /* LPSPI7: LPSPI7 IOMUX Pin Configuration */
fsl,pins = <
MX93_PAD_GPIO_IO07__LPSPI7_SCK 0x3fe
MX93_PAD_GPIO_IO06__LPSPI7_SOUT 0x3fe
MX93_PAD_GPIO_IO05__LPSPI7_SIN 0x3fe
>;
};
pinctrl_lpspi7_cs: lpspi7_cs_grp {
fsl,pins = <
MX93_PAD_GPIO_IO04__GPIO2_IO04 0x31e
>;
};
To debug the issue, I added logging in the TI ADS7950 driver code as follows:
Driver code:
diff --git a/drivers/iio/adc/ti-ads7950.c b/drivers/iio/adc/ti-ads7950.c
index 2cc9a9bd9db6..d4ce4917d1fb 100644
--- a/drivers/iio/adc/ti-ads7950.c
+++ b/drivers/iio/adc/ti-ads7950.c
@@ -377,6 +377,8 @@ static int ti_ads7950_read_raw(struct iio_dev *indio_dev,
if (ret < 0)
return ret;
+ printk("Address: %u\n", (unsigned int)chan->address);
+ printk("Extracted Value: %u\n", (unsigned int)TI_ADS7950_EXTRACT(ret, 12, 4));
if (chan->address != TI_ADS7950_EXTRACT(ret, 12, 4))
return -EIO;
Error:
root@imx93-iwg50m-sodimm:~# cat /sys/bus/iio/devices/iio\:device1/in_voltage0_raw
[ 100.929228] Address: 0
[ 100.931641] Extracted Value: 15
cat: '/sys/bus/iio/devices/iio:device1/in_voltage0_raw': Input/output error
root@imx93-iwg50m-sodimm:~# cat /sys/bus/iio/devices/iio\:device1/in_voltage1_raw
[ 103.849178] Address: 1
[ 103.851563] Extracted Value: 15
cat: '/sys/bus/iio/devices/iio:device1/in_voltage1_raw': Input/output error
root@imx93-iwg50m-sodimm:~# cat /sys/bus/iio/devices/iio\:device1/in_voltage2_raw
[ 106.253289] Address: 2
[ 106.255694] Extracted Value: 15
cat: '/sys/bus/iio/devices/iio:device1/in_voltage2_raw': Input/output error
root@imx93-iwg50m-sodimm:~# cat /sys/bus/iio/devices/iio\:device1/in_voltage3_raw
[ 108.949172] Address: 3
[ 108.951597] Extracted Value: 15
cat: '/sys/bus/iio/devices/iio:device1/in_voltage3_raw': Input/output error
root@imx93-iwg50m-sodimm:~#
Could you please advise what might be causing this behavior or if there are any potential issues in my configuration or setup?
Regards,
Daniel
