spidev to read eeprom id

Question

OS: Linux I'm writing a spidev application in userspace to read EEPROM id. I have my device tree entry as following:

spi0: spi@ffda4000 {
    compatible = "snps,dw-apb-ssi";
    #address-cells = <1>;
    #size-cells = <0>;
    reg = <0xffda4000 0x100>;
    interrupt-parent = <&intc>;
    interrupts = <GIC_SPI 101 IRQ_TYPE_LEVEL_HIGH>;
    num-cs = <2>;
    cs-gpios = <&porta 7 GPIO_ACTIVE_HIGH>, <&porta 0 GPIO_ACTIVE_HIGH>;
    bus-num = <0>;
    tx-dma-channel = <&pdma 16>;
    rx-dma-channel = <&pdma 17>;
    clocks = <&spi_m_clk>;
    status = "disabled";
};

and then:

&spi0 {
    status = "okay";
    m25p10_spi@0 {
        compatible = "m25p10";
        reg = <0>;  /* chip select */
        spi-max-frequency = <20000000>;
        /* m25p,fast-read; */
        enable-dma = <0>;
    };
    spidev@0 {
        compatible = "rohm,dh2228fv";
        reg = <0>;  /* chip select */
        spi-max-frequency = <20000000>;
        enable-dma = <0>;
    };
};

Idea is to have spidev at same node as m25p10 so that when user space application open handle to "/dev/spidev0.0", it is actually talking to m25p10. But I can't get linux boot up. Is there anything wrong with this approach?

Answer 1

This will not work. One device - one definition in DT.

Also, why do you need to have spidev device? You already have m25p10_spi, which should show up as MTD device (something like /dev/mtd0), and there should be no problems accessing it from user space.

UPDATE:

It looks like OP wants to keep MTD and read device unique ID via RDID command, which is not supported by current m25p10 driver.

I might be wrong, but for me the easiest solution would be to extend the driver to create sysfs entry with RDID data, that is read during probing.

Some valuable resources:

• LDD3
• Linux kernel documentation