On 18/10/19 7:52 AM, Simon Glass wrote:
Hi,
On Thu, 17 Oct 2019 at 08:28, Simon Glass sjg@chromium.org wrote:
Hi Vignesh,
On Wed, 16 Oct 2019 at 04:28, Vignesh Raghavendra vigneshr@ti.com wrote:
Hi Simon,
On 12/10/19 10:03 AM, Bin Meng wrote:
Hi Simon,
On Sat, Oct 12, 2019 at 11:08 AM Simon Glass sjg@chromium.org wrote:
Hi Bin,
On Wed, 9 Oct 2019 at 07:55, Bin Meng bmeng.cn@gmail.com wrote:
Hi Simon,
On Wed, Sep 25, 2019 at 10:12 PM Simon Glass sjg@chromium.org wrote: > > On x86 platforms the SPI flash can be mapped into memory so that the > contents can be read with normal memory accesses. > > Add a new SPI flash method to find the location of the SPI flash in > memory. This differs from the existing device-tree "memory-map" mechanism > in that the location can be discovered at run-time. >
Whats is the usecase? Why can't spi_flash_read() be used instead? Flash + Controller driver can underneath take care of using memory mapped mode to read data from flash right while making sure that access is within valid window?
I can see spi_flash_read_dm() but it does not support returning a pointer to the data, only reading it.
No, I was merely suggesting to use spi_flash_read_dm() (which underneath can be implemented by spi_mem_ops) to get data from flash instead of using get_mmap() to get MMIO pointer and then reading the data using that potiner.
Also I cannot find any documentation about any of this. I've been looking in the doc/ directory.
I found the spi_mem.h file but it doesn't mention the meaning of the in and out buffer pointers so I don't know how to use them.
Is there an API missing or just comments/documentation?
spi-mem.h has struct and APIs documented as kerneldoc: https://elixir.bootlin.com/u-boot/latest/source/include/spi-mem.h#L72 https://elixir.bootlin.com/u-boot/latest/source/include/spi-mem.h#L168
Note that clients should still use spi_flash_*() APIs to interact with flash. spi_mem_ops are not an alternative to spi_flash_*() APIs which are used by other drivers to read/write data from/to flash. This continues to be the same.
Apart from this I have found that the ich_spi driver does not work for APL since it apparently only supports 'hardware sequencing'. I did try getting software sequencing to work, but no dice.
In addition, I found that enabling SPI flash, etc. added about 6KB of code!
So I think it might be best to have two SPI drivers for x86 - one for software sequencing and one for hardware?
Regards, Simon