[U-Boot] [PATCH v4 05/29] dm: spi: Add a uclass for SPI

[Simon Glass]

Hi Stefan,

On 29 October 2014 07:02, Stefan Roese <sr at denx.de> wrote:
> Hi Simon!
>
> On 14.10.2014 07:41, Simon Glass wrote:
>>
>> Add a uclass which provides access to SPI buses and includes operations
>> required by SPI.
>>
>> For a time driver model will need to co-exist with the legacy SPI
>> interface
>> so some parts of the header file are changed depending on which is in use.
>> The exports are adjusted also since some functions are not available with
>> driver model.
>>
>> Boards must define CONFIG_DM_SPI to use driver model for SPI.
>
>
> I'm starting to use DM now. Finally! ;)

Great!

>
> In my case I'm implementing the Designware master SPI driver for the
> SoCFPGA. And since its a new driver it really makes sense to use DM
> directly. I'm starting to get an overview now. One thing though that I
> noticed is, that the SPI DM implementation seems to be a bit FDT centric.
> Please see below.
>
> <snip>
>
>> diff --git a/drivers/spi/spi-uclass.c b/drivers/spi/spi-uclass.c
>
> <snip>
>
>> +int spi_post_bind(struct udevice *dev)
>> +{
>> +       /* Scan the bus for devices */
>> +       return dm_scan_fdt_node(dev, gd->fdt_blob, dev->of_offset, false);
>> +}
>
>
> SoCFPGA currently does not support CONFIG_OF_CONTROL (no dtb supplied). So

In the kernel I see these files - are you sure it is not supported?

arch/arm/boot/dts/socfpga_arria5.dtsi
arch/arm/boot/dts/socfpga_arria5_socdk.dts
arch/arm/boot/dts/socfpga_cyclone5.dtsi
arch/arm/boot/dts/socfpga_cyclone5_socdk.dts
arch/arm/boot/dts/socfpga_cyclone5_sockit.dts
arch/arm/boot/dts/socfpga_cyclone5_socrates.dts
arch/arm/boot/dts/socfpga.dtsi
arch/arm/boot/dts/socfpga_vt.dts

> I'm planning to use platform_data to instantiate the device. Something like
> this in the board file:
>
> static const struct dw_spi_platdata spi_platdata = {
>         .base = SOCFPGA_SPIM0_ADDRESS,
> };
>
> U_BOOT_DEVICE(dw_spi) = {
>         .name = "dw_spi",
>         .platdata = &spi_platdata,
> };
>
> What would the non-fdt method have to be to bind the device in
> spi_post_bind() above?

We would have to create a new platform data structure that holds the
bus number, CS number and any other information. Then it will need to
cause spi_get_bus_and_cs() to locate it and do the right.

But first let's make sure that you really do have the platform that
doesn't use device tree... If it is ARM my understanding is that it
should.

Also see the SPI driver spi-howto.txt.

Regards,
Simon