[PATCH V2 2/2] mtd: msm_nand: Add initial msm nand driver support.
Matthieu CASTET
matthieu.castet at parrot.com
Wed Apr 27 08:38:02 EDT 2011
Hi,
Murali Nalajala a écrit :
> On 4/18/2011 1:02 PM, Matthieu CASTET wrote:
>> Hi,
>>
>> Murali Nalajala a écrit :
>>> Add initial msm nand driver support for Qualcomm MSM platforms.
>>> This driver is capable of handling both 2k and 4k page support
>>> nand devices.
>>>
>>> This driver was originally developed by Arve Hjønnevåg at google.
>>> Its source is available at
>>> http://android.git.kernel.org/?p=kernel/msm.git under
>>> android-msm-2.6.35 branch.
>>>
>>> CC: Dima Zavin<dima at android.com>
>>> CC: Brian Swetland<swetland at google.com>
>>> CC: Arve Hjønnevåg<arve at android.com>
>>> Signed-off-by: Murali Nalajala<mnalajal at codeaurora.org>
>>> ---
>>> Changes in V2
>>> * Turn most of the pr_info() calls into pr_debug().
>>>
>>> drivers/mtd/devices/Kconfig | 11 +
>>> drivers/mtd/devices/Makefile | 1 +
>>> drivers/mtd/devices/msm_nand.c | 1597 ++++++++++++++++++++++++++++++++++++++++
>>> drivers/mtd/devices/msm_nand.h | 77 ++
>>> 4 files changed, 1686 insertions(+), 0 deletions(-)
>>> create mode 100644 drivers/mtd/devices/msm_nand.c
>>> create mode 100644 drivers/mtd/devices/msm_nand.h
>>>
>> For the record, I am not sure it is a great idea to make nand drivers
>> independent of the nand layer.
>> By doing that you could change the expected behavior, and introduce bug
>> difficult to debug.
>>
>> Why do you need that ? Nand drivers can override callbacks of nand framework.
>>
>> Maybe because the nand layer call the driver page per page, and you want to
>> work with more than one page. But in this case you can extend nand layer.
>>
>> Or does your controller don't allow sending raw command ?
>> And in that case all the nand logic is in the nand controller ?
>
> Our controller doesn't allow sending RAW commands to the flash. All
> these commands are abstracted by the controller logic. Please refer the
> msm_nand.h file where you will find the commands which are different
> from the actual NAND device commands.
Ok, but does the controller does all other check : status check, ...
In the nand framework there is already controller like yours : see the denali.c
as example.
>
> eg: To send read/write data command to the device we configure the
> controller with page address & controller specific command. Then the
> controller itself takes care of generating the internal h/w signals
> required by the flash and it polls for the R/B signal & wait states are
> internally controlled by the h/w.
>
So you provide your own
chip->ecc.read_page
chip->ecc.read_page_raw
chip->ecc.read_oob
chip->write_page
chip->ecc.write_oob
and your done.
Matthieu
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