Help with ADS124S08 SPI ADC and its Linux driver

[Lmoio.1]

Hi, can someone help with ADS124S08 SPI ADC and its linux driver? I think the driver is correctly probed. I see /sys/devices/platform/soc/44004000.spi/spi_master/spi0/spi0.0/iio.device0/in_voltage0raw ...etc but it seems the device does not reply.

This is my device tree configuration:

&spi1 {
	status = "okay";
	pinctrl-names = "default";
	pinctrl-0 = <&spi1_pins_a>;
	cs-gpios = <&gpioz 3 GPIO_ACTIVE_LOW>;
    #address-cells = <1>;
    #size-cells = <0>;
        adc@0 {
            compatible = "ti,ads124s08";
            reg = <0>; /* CS #0 */
            spi-max-frequency = <1000000>;
            spi-cpha;
            reset-gpios = <&gpioi 2 GPIO_ACTIVE_LOW>;
        };
};

First, i don't see the cs going low when i try to read the voltages. Should the driver do that?

Second, the driver ti-ads124s08.c itself seems a bit incoherent with the datasheet. it defines the start conversion command as in the datasheet but then never uses it and instead it uses a made-up command.

#define ADS124S08_CMD_START	0x08
#define ADS124S08_START_CONV	0x01
 
...
 
ret = ads124s_write_cmd(indio_dev, ADS124S08_START_CONV);
		if (ret) {
			dev_err(&priv->spi->dev, "Start conversions failed\n");
			goto out;
		}

[PatrickF]

Hi,

did you enabled the SPI1 kernel clock in the device tree ?

Located in the &rcc node, you should have something like :

st,pkcs = <
      ....
      CLK_SPI2S1_XXXX <== could be PLL4P, PLL4Q, CKPER or PLL3R
      ....
>;

could be checked in /sys/kernel/debug/clk/clk_summary by using such kind of command :

grep -E "clock|spi" /sys/kernel/debug/clk/clk_summary | sed 's,\s\+, ,g' | column -t

Regards,

Patrick

[Lmoio.1 · Accepted solution]

Hi @PatrickF​ 

i managed to make it work; linux driver is bugged and very basic and cannot handle the whole behaviour of the device. So i had to modify the driver to write specific registers.

Thanks

[issam]

Dear Lmoio,

Could you share with us the driver.

Thank you very much,

Best Regards,

Issam