[U-Boot] [PATCH v3 05/29] dm: spi: Add a uclass for SPI

[Simon Glass]

Hi Jagan,

On 10 October 2014 11:31, Jagan Teki <jagannadh.teki at gmail.com> wrote:
> Hi Simon,
>
> Can you please see my comments below, I'm relating more about cs and bus
> valid scenario which is available on current drivers wrt dm-spi.
>
> On 30 September 2014 01:05, Simon Glass <sjg at chromium.org> 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.
>>
>> Signed-off-by: Simon Glass <sjg at chromium.org>
>> ---
>>
>> Changes in v3:
>> - Add a cs_info() method to the driver model SPI API
>
> I think this gives the enough info regarding cs on particular controller what
> about the bus usage - which is also specific to controller it self, right?
>
> Say - spi controller on a particular soc, have spi0, spi1 means two buses
> and 4 cs lines, cs0-cs3. How is this works in that case?
>
> And also I saw tegra20_sflash.c validates only cs
>
> int tegra20_sflash_cs_info(struct udevice *bus, unsigned int cs,
>                            struct spi_cs_info *info)
>
> What about bus number check this particular tegra spi controller is concern.

The bus device is passed in as a pointer. The bus number gets looked
up to find the device for that bus number. See spi_get_bus_and_cs()
for that.

This is good because drivers no longer need to validate the bus number.

>
>> - Add a uclass for a generic SPI device (for use with the 'sspi' command)
>> - Add missing comments to spi.h
>> - Correct typo where 'slave' should say 'bus'
>> - Fix two comment typos
>> - Put the cs member back into spi_slave
>> - Use an explicit chip select value instead of reusing device sequence number
>>
>> Changes in v2:
>> - Add missing comments for struct spi_slave
>> - Fix code nits from Daniel Schwierzeck
>> - Use 'bus' instead of 'dev' to make the API clearer
>>
>>  common/exports.c         |   4 +-
>>  drivers/spi/Makefile     |   4 +
>>  drivers/spi/spi-uclass.c | 390 +++++++++++++++++++++++++++++++++++++++++++++++
>>  include/dm/uclass-id.h   |   2 +
>>  include/spi.h            | 254 +++++++++++++++++++++++++++++-
>>  5 files changed, 650 insertions(+), 4 deletions(-)
>>  create mode 100644 drivers/spi/spi-uclass.c
>>


>> +int spi_cs_is_valid(unsigned int busnum, unsigned int cs)
>
> Who is the caller for this?

This can be called by boards, or anywhere really. It replaces the
function with the same purpose in the old SPI framework.

Regards,
Simon