[U-Boot] [PATCH v2 12/38] x86: spi: Add a driver for the Intel Fast SPI interface

[Bin Meng]

Hi Simon,

On Sat, Oct 19, 2019 at 10:44 AM Simon Glass <sjg at chromium.org> wrote:
>
> Hi Bin,
>
> On Wed, 9 Oct 2019 at 07:10, Bin Meng <bmeng.cn at gmail.com> wrote:
>>
>> Hi Simon,
>>
>> On Wed, Sep 25, 2019 at 10:12 PM Simon Glass <sjg at chromium.org> wrote:
>> >
>> > This provides access to SPI flash both through a read-only memory map and
>> > with operations to erase and write flash. It supports 4KB or 64KB erase
>> > sizes.
>> >
>>
>> I read the SPI controller chapter in the datasheet of apollolake as
>> well as some latest x86 desktop processors and believe they are
>> compatible with the existing LPC SPI controller, the one used in ICH7
>> and ICH9. In fact, in Linux, these SPI controllers are supported by
>> the same intel-spi-pci.c driver (probe interface, PCI), and is
>> actually using the same intel-spi.c core driver.
>>
>> So I think we should consider expanding the existing ICH SPI driver in
>> U-Boot to support the PCI variants too.
>
>
> As discussed elsewhere I'll give this another try.
>>
>>
>> > This driver is used by Apollolake.
>> >
>> > Signed-off-by: Simon Glass <sjg at chromium.org>
>> > ---
>> >
>> > Changes in v2:
>> > - Add the missing header file
>> > - Add support for of-platdata for TPL
>> >
>> >  drivers/mtd/spi/Kconfig          |   9 +
>> >  drivers/mtd/spi/Makefile         |   1 +
>> >  drivers/mtd/spi/intel_fast_spi.c | 360 +++++++++++++++++++++++++++++++
>> >  3 files changed, 370 insertions(+)
>> >  create mode 100644 drivers/mtd/spi/intel_fast_spi.c
>> >
>
>
> [..]
>
>>
>> > +static void fast_spi_early_init(struct udevice *dev)
>> > +{
>> > +       struct fast_spi_platdata *plat = dev_get_platdata(dev);
>> > +       pci_dev_t pdev = plat->bdf;
>> > +
>> > +       /* Clear BIT 1-2 SPI Command Register */
>> > +       //remove
>> > +       pci_x86_clrset_config(pdev, PCI_COMMAND, PCI_COMMAND_MASTER |
>> > +                             PCI_COMMAND_MEMORY, 0, PCI_SIZE_8);
>> > +
>> > +       /* Program Temporary BAR for SPI */
>> > +       pci_x86_write_config(pdev, PCI_BASE_ADDRESS_0,
>> > +                            plat->mmio_base | PCI_BASE_ADDRESS_SPACE_MEMORY,
>> > +                            PCI_SIZE_32);
>> > +
>> > +       /* Enable Bus Master and MMIO Space */
>> > +       pci_x86_clrset_config(pdev, PCI_COMMAND, 0, PCI_COMMAND_MASTER |
>> > +                             PCI_COMMAND_MEMORY, PCI_SIZE_8);
>> > +
>> > +       /*
>> > +        * Disable the BIOS write protect so write commands are allowed.
>> > +        * Enable Prefetching and caching.
>> > +        */
>> > +       pci_x86_clrset_config(pdev, SPIBAR_BIOS_CONTROL,
>> > +                             SPIBAR_BIOS_CONTROL_EISS |
>> > +                             SPIBAR_BIOS_CONTROL_CACHE_DISABLE,
>> > +                             SPIBAR_BIOS_CONTROL_WPD |
>> > +                             SPIBAR_BIOS_CONTROL_PREFETCH_ENABLE, PCI_SIZE_8);
>>
>> I wonder why are these needed, IIUC we rely on FSP2 to initialize the
>> SoC and I believe for SPI these are some basic settings and registers
>> should have already be programmed to sane values, no?
>
>
> Which part of the FSP2? This code is executed in TPL so no part of the FSP has been executed yet. Even when we figure out how to run FSP-T (which will run befor ethis code) I am not sure that the FSP will do this.
>

Per the FSP2 spec, such silicon specific initialization are covered by
FSP-S. I am not sure if SPI specific registers are touched by FSP-T as
well.

Regards,
Bin