On 08/07/2015 03:46 PM, Michal Suchanek wrote:
[snip]
> On 7 August 2015 at 10:35, Vignesh R <vigneshr@xxxxxx> wrote:
>>
>>
>> On 08/07/2015 01:08 PM, Michal Suchanek wrote:
>>
>>> Now since the description is clearer it's obvious that ti-qspi cannot
>>> work fully mmapped as fsl-qspi does because the setup has to be done
>>> over normal spi access and using non-m25p80 devices on the same bus is
>>> a requirement.
>>>
>>> The place where it is known if a transfer can use the mmap access is m25p80.c
>>>
>>> So my suggestion is
>>>
>>> - add a new method for spi master that gets the read opcode, dummy
>>> length, address, address length, buffer, buffer length and performs
>>> read from the flash memory in a hardware-specific way
>>>
>>> - add a check in m25p80.c that the master supports this feature and if
>>> so use it (eg check that the method is non-null)
>>>
>>> Presumably if some new SPI controllers with similar feature are
>>> supported in the future they can use the same inteface because you
>>> pass on everything the m25p80 read knows.
>>>
>>
>> Ok... Do you mean something like this?
>>
>> I will take m25p80 as example but can be expanded for any flash.
>>
>> In include/linux/mtd.h:
>> struct spi_mtd_config_info {
>> struct spi_device *spi;
>> u32 page_size;
>> u8 addr_width;
>> u8 erase_opcode;
>> u8 read_opcode;
>> u8 read_dummy;
>> u8 program_opcode;
>> enum read_mode flash_read;
>>
>> } /* subset of struct spi_nor */
>>
>
> I would just pass these as separate arguments to the function but whatver.
>
>> In m25p80.c:
>>
>> static int m25p80_read(struct spi_nor *nor, loff_t from,
>> size_t len, size_t *retlen,
>> u_char *buf)
>> {
>> struct spi_mtd_config_info info;
>> struct spi_device *spi;
>>
>> if (spi->master->spi_mtd_mmap_read) {
>> /* Populate spi_mtd_config_info */
>> spi->master->spi_mtd_mmap_read(&info, from, len,
>> retlen, buf);
>> }
>> else {
>> /* no mtd specific acceleration supported try normal
>> * SPI way of communicating with flash
>> * continue with current code
>> * set up spi_message and call spi_sync()
>> */
>> }
>>
>> }
>>
>> In spi-ti-qspi.c:
>> Implement spi_mtd_mmap_read while holding master->bus_lock mutex.
>>
>
I will re-submit patches based on the above idea, if there are no
further comments..
--
Thanks
Vignesh
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