On Fri, Feb 13, 2009 at 3:40 AM, Henk Stegeman [off-list ref] wrote:

I'm busy adding support for slave deviced behind mpc52xx-psc-spi.
One complication I have is that my SPI slave device has an interrupt output
to the CPU.
My idea is to add it as a gpios property in the slave device's
configuration:

        spi@2400 {        // PSC3 (SPI IF to the IO-controller )
            device_type = "spi";
            #address-cells = <1>;
            #size-cells = <0>;
            compatible = "fsl,mpc5200-psc-spi","fsl,mpc5200b-psc-spi";
            cell-index = <2>;
            reg = <0x2400 0x100>;
            interrupts = <2 3 0>;
            interrupt-parent = <&mpc5200_pic>;
            gpios = <&gpt4 0 0>;

            io-controller@0 {
                compatible = "microkey,smc4000io";
                spi-max-frequency = <1000000>;
                reg = <0>;
                // gpios: first is IRQ to cpu
                gpios = <&gpt6 0 0>;
            };

There is a better way to do this, and driver support for it is
currently merged into Ben Herrenschmidt's -next tree.

Do this instead:
        io-controller@0 {
                compatible = "microkey,smc4000io";
                spi-max-frequency = <1000000>;
                reg = <0>;
                interrupt-controller = < &gpt6 >;     // Use GPT6 as
the IRQ controller
                interrupts = < 1 >;    // And make it rising edge.
        };

Then add these two properties to the GPT node:

        interrupt-controller;
        #interrupt-cells = <1>;

Then you can use normal irq_of_parse_and_map() to set up your handler.

How should I then register my spi slave driver? My smc4000io_probe function
gets called correctly by of_spi support but when I register as follows:

static struct spi_driver smc4000io_driver = {
    .driver = {
        .name    = "smc4000io",
        .bus    = &spi_bus_type,
        .owner    = THIS_MODULE,
    },
    .probe        = smc4000io_probe,
    .remove        = __devexit_p(smc4000io_remove),
};

static int __init smc4000io_init(void)
{
    return spi_register_driver(&smc4000io_driver);
}

static void __exit smc4000io_exit(void)
{
    spi_unregister_driver(&smc4000io_driver);
}

module_init(smc4000io_init);

Yes, this is right.  The psc_spi driver automatically registers all
spi children that it finds in the device tree onto the SPI bus.
Therefore registering an spi_driver() is the right thing to do.

But when I do:

static struct of_platform_driver smc4000_spi_of_driver = {
    .name = "smc4000io",
    .match_table = smc4000io_of_match,
    .probe = smc4000io_of_probe,
    .remove        = __devexit_p(smc4000io_of_remove),
};

static int __init smc4000io_init(void)
{
    return of_register_platform_driver(&smc4000_spi_of_driver);
}
module_init(smc4000io_init);

Then my smc4000io_of_probe function never gets called.

Correct.  of_platform_driver isn't useful in this case because the
device cannot exist independently of the SPI bus.  Plus an
of_platform_device doesn't provide any information about the SPI bus
itself.

g.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.