Re: [Spi-devel-general] SPI core / 20050920

[Vitaly W. <vw...@ru...>]

dmitry pervushin wrote:

<snip>

>3.1 The SPI outline
>
>The SPI infrastructure deals with several levels of abstraction. They are 
>"SPI bus", "SPI bus driver", "SPI device" and "SPI device driver". The 
>"SPI bus" is hardware device, which usually called "SPI adapter", and has 
>"SPI devices" connected. From the Linux' point of view, the "SPI bus" is
>structure of type platform_device, and "SPI device" is structure of type
>spi_device. The "SPI bus driver" is the driver which controls the whole 
>  
>
Is there platform_bus structure BTW? :)

<snip>

>To handle DMA transfers on SPI bus, any device driver might provide special
>callbacks to allocate/free/get access to buffer. These callbacks are defined 
>in subsection iii of section 4.
>To send data using DMA, the buffers should be allocated using 
>dma_alloc_coherent function. Usually buffers are allocated statically or
>using kmalloc function. 
>To allow drivers to allocate buffers in non-standard 
>  
>
...?

>When one allocates the structure for spi message, it needs to provide target
>  
>
one = he :)

>device. If its driver wants to allocate buffer in driver-specific way, it may
>provide its own allocation/free methods: alloc and free. If driver does not
>provide these methods, kmalloc and kfree will be used.
>  
>
suggest: ...and it's also up to him to create a specific structure and 
return this structure pointer in alloc and cast to it in free.


Best regards,
   Vitaly