WANG YiFei wrote:
> Hi TieJun,
>
> Thanks a lot for your reply.
> So far, I can get ppc405 spi to initialize, however
> failed at MCP23S17's probe() routine, I checked the
> code, it's due to un-initialized platform data. Here
> is my part of dts:
>
> s...@ef600600 {
> device_type = "spi";
> compatible = "ibm,ppc4xx-spi", "ibm,spi";
> reg = <0xef600600 0x7>;
> interrupt-parent = <0x2>;
> interrupts = <0x8 0x4>;
> #address-cells = <0x1>;
> #size-cells = <0x0>;
> gpios = <0>; /* cs */
>
> spi_g...@0 {
> compatible = "mcp,mcp23s08";
> spi-max-frequency = <1000000>;
> reg = <0>;
> };
> };
>
> I don't know how to provide platform data from dts although
> I understand the concept from code. Do I only need to modify
> dts OR I need to write some code to supply platform data? Do
> you have any URL or sample code to show passing of platform
> data?
Often you SPI bus driver should call spi_register_master() to register your SPI
master controller. Then please go to the following path:
======
spi_register_master()
|
+ scan_boardinfo()
|
+ spi_new_device()
^
Here refer to the function,
------
struct spi_device *spi_new_device(struct spi_master *master,
struct spi_board_info *chip)
{
struct spi_device *proxy;
......
proxy->dev.platform_data = (void *) chip->platform_data;
......
status = spi_add_device(proxy);
......
And as I previously comment 'spi->dev.platform_data' would be passed to your
platform_data resided in your probe hook within your spi device driver.
So firstly you should register call spi_register_board_info() to register one
given spi_board_info by parsing your device nodes from your dts.
I think you can refer to the file, arch/powerpc/platforms/83xx/mpc832x_rdb.c.
>
> Anyway, thanks a lot for guiding me.
You're welcome :)
Tiejun
> YiFei
>
> -----Original Message-----
> From: tiejun.chen [mailto:tiejun.c...@windriver.com]
> Sent: Wednesday, October 13, 2010 11:09 AM
> To: WANG YiFei
> Cc: linuxppc-...@ozlabs.org
> Subject: Re: ppc405 + MCP23S17
>
> WANG YiFei wrote:
>> Hi,
>>
>>
>>
>> I'm a newbie for linux device driver development.
>>
>> We have a custom ppc405 board which has MCP23S17
>>
>> (16-Bit I/O Expander with SPI Interface) on it.
>>
>> I noticed that current kernel has MCP23S08 driver
>>
>> support, I'd like to know:
>>
>> 1. if passing platform data to MCP23S08 driver, can it make
>>
>> MCP23S17 work?
>>
>
> These chips should be same vendor product so I think 16-bit mcp23s17 may be
> compatible to 8-bit modes. But you have to check the data sheet to confirm
> this
> and track how to configure that as 8-bit mode. After that it's possible to run
> mcp23s17 with mcp23s08.c.
>
>> 2. Generally, I'd like to know how to pass platform data to
>>
>> a particular device driver. In my mind, platform data should
>>
>> not be in driver code, right? However, I don't know where is
>
> Firstly you should define this on your dts. Then parse that to register
> corresponding of_platform_device or platform_device when you setup your target
> on <your target>.c.
>
> When spi_register_driver prober successfully, you can get the platform_data
> from
> associated spi device.
>
>> the suitable place to pass platform data to driver.
>>
>> 3. How to describe this in dts file?
>>
>
> You can get more from the file,
> Documentation/powerpc/dts-bindings/spi-bus.txt.
> Or refer to those existed spi nodes on other platform dts.
>
> Tiejun
>
>>
>>
>> Thanks in advance,
>>
>> YiFei
>>
>>
>>
>>
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
