[PATCH v2 10/10] riscv: Add support for SPI on Kendryte K210

[Heinrich Schuchardt]

On 8/7/20 4:43 PM, Sean Anderson wrote:
> This patch enables configs necessary for using SPI. It also adds some
> documentation.
>
> Signed-off-by: Sean Anderson <seanga2 at gmail.com>
> ---
>
> Changes in v2:
> - Add Gigadevice SPI chips to dependencies
>
>  board/sipeed/maix/Kconfig          | 11 ++++
>  configs/sipeed_maix_bitm_defconfig |  8 +++
>  doc/board/sipeed/maix.rst          | 94 +++++++++++++++++++-----------
>  3 files changed, 80 insertions(+), 33 deletions(-)
>
> diff --git a/board/sipeed/maix/Kconfig b/board/sipeed/maix/Kconfig
> index 4c42dd2087..48a4e9dc1a 100644
> --- a/board/sipeed/maix/Kconfig
> +++ b/board/sipeed/maix/Kconfig
> @@ -53,4 +53,15 @@ config BOARD_SPECIFIC_OPTIONS
>  	imply CMD_GPIO
>  	imply LED
>  	imply LED_GPIO
> +	imply SPI
> +	imply DESIGNWARE_SPI
> +	imply SPI_FLASH_GIGADEVICE
> +	imply SPI_FLASH_WINBOND
> +	imply DM_MTD
> +	imply SPI_FLASH_MTD
> +	imply CMD_MTD
> +	imply ENV_IS_IN_SPI_FLASH
> +	imply MMC
> +	imply MMC_BROKEN_CD
> +	imply MMC_SPI
>  endif
> diff --git a/configs/sipeed_maix_bitm_defconfig b/configs/sipeed_maix_bitm_defconfig
> index f48f7f06e9..7f644e7a37 100644
> --- a/configs/sipeed_maix_bitm_defconfig
> +++ b/configs/sipeed_maix_bitm_defconfig
> @@ -1,6 +1,14 @@
>  CONFIG_RISCV=y
> +CONFIG_ENV_SIZE=0x2000
> +CONFIG_ENV_SECT_SIZE=0x1000
> +CONFIG_ENV_OFFSET=0x7C000
> +CONFIG_ENV_OFFSET_REDUND=0x7E000
>  CONFIG_TARGET_SIPEED_MAIX=y
>  CONFIG_ARCH_RV64I=y
> +CONFIG_USE_BOOTCOMMAND=y
> +CONFIG_BOOTCOMMAND="sf probe;mtd read kernel 80000000;go 80000000"

If no kernel is present, this will let your system hang.

"go" does not check that whatever you loaded from mtd is a kernel. That
is why we have commands like bootm.

> +CONFIG_MTDIDS_DEFAULT="nor0=spi3.0"
> +CONFIG_MTDPARTS_DEFAULT="spi3.0:496k(u-boot),16k(env),5632k(kernel),10240k(data)"

The size of u-boot.bin may exceed 496 KiB depending on the options
selected. Mine is currently 543589 bytes. When starting with OpenSBI
another 70+ KiB will be needed.

If we overwrite 5632 KiB from the kernel partition, this may overwrite
the relocated U-Boot.

When an SD-card is worn out I can replace it. When the SPI flash is worn
out I have to replace the device.

We can put the kernel and the environment onto the SD card. I would
suggest to use SPI only for OpenSBI and U-Boot. Please, use
CONFIG_DISTRO_BOOT.

>  CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
>  # CONFIG_NET is not set
>  # CONFIG_INPUT is not set
> diff --git a/doc/board/sipeed/maix.rst b/doc/board/sipeed/maix.rst
> index 1865e2adfb..fa78bcd51c 100644
> --- a/doc/board/sipeed/maix.rst
> +++ b/doc/board/sipeed/maix.rst
> @@ -46,42 +46,14 @@ Boot output should look like the following:
>      U-Boot 2020.04-rc2-00087-g2221cc09c1-dirty (Feb 28 2020 - 13:53:09 -0500)
>
>      DRAM:  8 MiB
> +    MMC:   spi at 53000000:slot at 0: 0

Actual output is

MMC:   regs=0000000053000000 max-frequency=25000000

>      In:    serial at 38000000
>      Out:   serial at 38000000
>      Err:   serial at 38000000

As we do not check if a kernel is available:

MTD device kernel not found, ret -19
## Starting application at 0x80000000 ...

And then hanging.

Best regards

Heinrich

> -    =>
> -
> -Loading Images
> -^^^^^^^^^^^^^^
> -
> -To load a kernel, transfer it over serial.
> -
> -.. code-block:: none
> -
> -    => loady 80000000 1500000
> -    ## Switch baudrate to 1500000 bps and press ENTER ...
> -
> -    *** baud: 1500000
> -
> -    *** baud: 1500000 ***
> -    ## Ready for binary (ymodem) download to 0x80000000 at 1500000 bps...
> -    C
> -    *** file: loader.bin
> -    $ sz -vv loader.bin
> -    Sending: loader.bin
> -    Bytes Sent:2478208   BPS:72937
> -    Sending:
> -    Ymodem sectors/kbytes sent:   0/ 0k
> -    Transfer complete
> -
> -    *** exit status: 0 ***
> -    ## Total Size      = 0x0025d052 = 2478162 Bytes
> -    ## Switch baudrate to 115200 bps and press ESC ...
> -
> -    *** baud: 115200
> -
> -    *** baud: 115200 ***
> -    =>
> +    Hit any key to stop autoboot:  0
> +    SF: Detected w25q128fw with page size 256 Bytes, erase size 4 KiB, total 16 MiB
> +    Reading 5242880 byte(s) at offset 0x00000000
> +    ## Starting application at 0x80000000 ...
>
>  Running Programs
>  ^^^^^^^^^^^^^^^^
> @@ -163,6 +135,62 @@ To run legacy images, use the ``bootm`` command:
>      argv[0] = "<NULL>"
>      Hit any key to exit ...
>
> +Flashing Images
> +---------------
> +
> +To flash a kernel, transfer it over serial, then write it to the kernel
> +partition.
> +
> +.. code-block:: none
> +
> +    => loady 80000000 1500000
> +    ## Switch baudrate to 1500000 bps and press ENTER ...
> +
> +    *** baud: 1500000
> +
> +    *** baud: 1500000 ***
> +    ## Ready for binary (ymodem) download to 0x80000000 at 1500000 bps...
> +    C
> +    *** file: loader.bin
> +    $ sz -vv loader.bin
> +    Sending: loader.bin
> +    Bytes Sent:2478208   BPS:72937
> +    Sending:
> +    Ymodem sectors/kbytes sent:   0/ 0k
> +    Transfer complete
> +
> +    *** exit status: 0 ***
> +    ## Total Size      = 0x0025d052 = 2478162 Bytes
> +    ## Switch baudrate to 115200 bps and press ESC ...
> +
> +    *** baud: 115200
> +
> +    *** baud: 115200 ***
> +    => sf probe
> +    SF: Detected w25q128fw with page size 256 Bytes, erase size 4 KiB, total 16 MiB
> +    => mtd write kernel 80000000 0 25d052
> +    Writing 2478162 byte(s) at offset 0x00000000
> +
> +Partition Scheme
> +^^^^^^^^^^^^^^^^
> +
> +There is no partition scheme specified by the manufacturer. The only requirement
> +imposed by the firmware is that offset 0 will be loaded and ran. The default
> +partition scheme is
> +
> +========= ======== ======
> +Partition Offset   Size
> +========= ======== ======
> +u-boot    0x000000 496k
> +env       0x07C000 16k
> +kernel    0x080000 5M
> +data      0x580000 10.5M
> +========= ======== ======
> +
> +**NB:** kflash adds a 5-byte header to payloads (and a 32-byte trailer) to all
> +payloads it flashes. If you use kflash to flash your payload, you will need to
> +account for this header when specifying what offset in spi flash to load from.
> +
>  Pin Assignment
>  --------------
>
>