[U-Boot] [PATCH v4 1/1] board: arm: Add support for Broadcom BCM7445

[Thomas Fitzsimmons]

Hi Bin,

Bin Meng <bmeng.cn at gmail.com> writes:

> Hi Thomas,
>
> On Sat, Jun 9, 2018 at 6:06 AM Thomas Fitzsimmons <fitzsim at fitzsim.org> wrote:
>>
>> Add support for loading U-Boot on the Broadcom 7445 SoC.  This port
>> assumes Broadcom's BOLT bootloader is acting as the second stage
>> bootloader, and U-Boot is acting as the third stage bootloader, loaded
>> as an ELF program by BOLT.
>>
>> Signed-off-by: Thomas Fitzsimmons <fitzsim at fitzsim.org>
>> Cc: Stefan Roese <sr at denx.de>
>> Cc: Tom Rini <trini at konsulko.com>
>> Cc: Florian Fainelli <f.fainelli at gmail.com>
>> ---
>> Changes for v4:
>>    - Use high timer register for get_ticks
>>    - Move hard-coded register addresses from Kconfig to header
>>    - Document I-cache/D-cache expectation
>>
>>  MAINTAINERS                                     |  10 +
>>  arch/arm/Kconfig                                |  12 +
>>  arch/arm/Makefile                               |   1 +
>>  arch/arm/mach-bcmstb/Kconfig                    |  36 ++
>>  arch/arm/mach-bcmstb/Makefile                   |   8 +
>>  arch/arm/mach-bcmstb/include/mach/gpio.h        |  11 +
>>  arch/arm/mach-bcmstb/include/mach/hardware.h    |  11 +
>>  arch/arm/mach-bcmstb/include/mach/prior_stage.h |  30 ++
>>  arch/arm/mach-bcmstb/include/mach/sdhci.h       |  15 +
>>  arch/arm/mach-bcmstb/include/mach/timer.h       |  13 +
>>  arch/arm/mach-bcmstb/lowlevel_init.S            |  21 ++
>>  board/broadcom/bcmstb/MAINTAINERS               |   7 +
>>  board/broadcom/bcmstb/Makefile                  |   8 +
>>  board/broadcom/bcmstb/bcmstb.c                  | 194 +++++++++++
>>  configs/bcm7445_defconfig                       |  27 ++
>>  doc/README.bcm7xxx                              | 150 ++++++++
>>  drivers/mmc/Kconfig                             |  11 +
>>  drivers/mmc/Makefile                            |   1 +
>>  drivers/mmc/bcmstb_sdhci.c                      |  67 ++++
>>  drivers/spi/Kconfig                             |   7 +
>>  drivers/spi/Makefile                            |   1 +
>>  drivers/spi/bcmstb_spi.c                        | 439 ++++++++++++++++++++++++
>>  drivers/spi/spi-uclass.c                        |   2 +-
>>  dts/Kconfig                                     |   7 +
>>  include/configs/bcm7445.h                       |  26 ++
>>  include/configs/bcmstb.h                        | 183 ++++++++++
>>  include/fdtdec.h                                |   4 +
>>  lib/fdtdec.c                                    |   4 +
>>  28 files changed, 1305 insertions(+), 1 deletion(-)
>>  create mode 100644 arch/arm/mach-bcmstb/Kconfig
>>  create mode 100644 arch/arm/mach-bcmstb/Makefile
>>  create mode 100644 arch/arm/mach-bcmstb/include/mach/gpio.h
>>  create mode 100644 arch/arm/mach-bcmstb/include/mach/hardware.h
>>  create mode 100644 arch/arm/mach-bcmstb/include/mach/prior_stage.h
>>  create mode 100644 arch/arm/mach-bcmstb/include/mach/sdhci.h
>>  create mode 100644 arch/arm/mach-bcmstb/include/mach/timer.h
>>  create mode 100644 arch/arm/mach-bcmstb/lowlevel_init.S
>>  create mode 100644 board/broadcom/bcmstb/MAINTAINERS
>>  create mode 100644 board/broadcom/bcmstb/Makefile
>>  create mode 100644 board/broadcom/bcmstb/bcmstb.c
>>  create mode 100644 configs/bcm7445_defconfig
>>  create mode 100644 doc/README.bcm7xxx
>>  create mode 100644 drivers/mmc/bcmstb_sdhci.c
>>  create mode 100644 drivers/spi/bcmstb_spi.c
>>  create mode 100644 include/configs/bcm7445.h
>>  create mode 100644 include/configs/bcmstb.h
>>
>
> [snip]
>
>> diff --git a/drivers/spi/spi-uclass.c b/drivers/spi/spi-uclass.c
>> index d2d091f..c517d06 100644
>> --- a/drivers/spi/spi-uclass.c
>> +++ b/drivers/spi/spi-uclass.c
>> @@ -273,7 +273,7 @@ int spi_get_bus_and_cs(int busnum, int cs, int speed, int mode,
>>         bool created = false;
>>         int ret;
>>
>> -#if CONFIG_IS_ENABLED(OF_PLATDATA)
>> +#if CONFIG_IS_ENABLED(OF_PLATDATA) || CONFIG_IS_ENABLED(OF_PRIOR_STAGE)
>
> Could you please explain this change a little bit? Why should we call
> uclass_first_device_err() for OF_PRIOR_STAGE?
>
>>         ret = uclass_first_device_err(UCLASS_SPI, &bus);
>>  #else
>>         ret = uclass_get_device_by_seq(UCLASS_SPI, busnum, &bus);

On the BCM7445 eval board, the prior-stage-provided device tree does not
have an alias for spi0, though it has aliases for other device types; I
don't know why this is the case, but I don't have control over what the
prior stage bootloader (Broadcom's BOLT) provides.  Without that alias,
uclass_get_device_by_seq fails to find the SPI bus (and so U-Boot can't
find the SPI flash device that stores its environment).

At the time, I checked other ARM device trees in the Linux kernel and
not many set an alias for spi0, so I wrote the patch to choose the first
SPI bus.  Doing so was in line with what CONFIG_OF_PLATDATA did on
boards that wanted to avoid device tree accesses.

I see that since I introduced CONFIG_OF_PRIOR_STAGE, several other ports
have started using it, so there's probably a need to generalize this; if
other prior stage bootloaders provide SPI aliases then there should be a
way for this code to use them.

>> diff --git a/dts/Kconfig b/dts/Kconfig
>> index 0cef225..a1a92f2 100644
>> --- a/dts/Kconfig
>> +++ b/dts/Kconfig
>> @@ -101,6 +101,13 @@ config OF_HOSTFILE
>>           This is only useful for Sandbox.  Use the -d flag to U-Boot to
>>           specify the file to read.
>>
>> +config OF_PRIOR_STAGE
>> +       bool "Prior stage bootloader DTB for DT control"
>> +       help
>> +         If this option is enabled, the device tree used for DT
>> +         control will be read from a device tree binary, at a memory
>> +         location passed to U-Boot by the prior stage bootloader.
>> +
>>  endchoice
>>
>
> [snip]

Thomas