Hi Andre,
On 01:05 Thu 17 Apr , Andre Przywara wrote:
> Some boards with Allwinner SoCs feature a "FEL" key, sometimes also
> labelled "uboot", which triggers the BootROM FEL mode, when pressed upon
> power-on or reset. This allows to access the SoC's memory via USB OTG,
> and to upload and execute code. There is a tool to upload our U-Boot image
> and immediately boot it, when the SoC is in FEL mode.
>
> To mimic this convenient behaviour on boards without such a dedicated key,
> we can query a GPIO pin very early in the SPL boot, then trigger the
> BootROM FEL routine. There has not been much of a SoC or board setup at
> this point, so we enter the BROM in a rather pristine state still. On
> 64-bit SoCs the required AArch32 reset guarantees a clean CPU state anyway.
>
> Any GPIO can be used for that, the signal is expected to be active low,
> consequently we enable the pull-up resistors for that pin. A board (or a
> user) is expected to specify the GPIO name using the
> CONFIG_SUNXI_FAKE_FEL_PIN Kconfig variable. When this variable is not set,
> the compiler will optimise away the call.
>
> Call the code first thing in board_init_f(), which is the first sunxi
> specific C routine.
>
> Signed-off-by: Andre Przywara <andre.przyw...@arm.com>
> ---
> arch/arm/mach-sunxi/Kconfig | 10 ++++++++++
> arch/arm/mach-sunxi/board.c | 31 +++++++++++++++++++++++++++++++
> 2 files changed, 41 insertions(+)
>
> diff --git a/arch/arm/mach-sunxi/Kconfig b/arch/arm/mach-sunxi/Kconfig
> index ab432390d3c..f1cfdb548bc 100644
> --- a/arch/arm/mach-sunxi/Kconfig
> +++ b/arch/arm/mach-sunxi/Kconfig
> @@ -825,6 +825,16 @@ config USB3_VBUS_PIN
> ---help---
> See USB1_VBUS_PIN help text.
>
> +config SUNXI_FAKE_FEL_PIN
> + string "fake FEL GPIO pin"
> + default ""
> + ---help---
> + Define a GPIO that shall force entering FEL mode when a button
> + connected to this pin is pressed at boot time. This must be an
> + active low signal, the internal pull-up resistors are activated.
> + This takes a string in the format understood by sunxi_name_to_gpio,
> + e.g. PH1 for pin 1 of port H.
> +
> config I2C0_ENABLE
> bool "Enable I2C/TWI controller 0"
> default y if MACH_SUN4I || MACH_SUN5I || MACH_SUN7I || MACH_SUN8I_R40
> diff --git a/arch/arm/mach-sunxi/board.c b/arch/arm/mach-sunxi/board.c
> index 701899ee4b2..4ee0b333176 100644
> --- a/arch/arm/mach-sunxi/board.c
> +++ b/arch/arm/mach-sunxi/board.c
> @@ -457,8 +457,39 @@ u32 spl_mmc_boot_mode(struct mmc *mmc, const u32
> boot_device)
> return result;
> }
>
> +static void check_fake_fel_button(void)
> +{
> + u32 brom_entry = 0x20;
> + int pin, value, mux;
> +
> + /* check for empty string at compile time */
> + if (sizeof(CONFIG_SUNXI_FAKE_FEL_PIN) == sizeof(""))
use 'sizeof("")' to express it's an empty string _explicitly_?
otherwise, I'd prefer '0' simply (save few chars)..
> + return;
> +
> + pin = sunxi_name_to_gpio(CONFIG_SUNXI_FAKE_FEL_PIN);
> + if (pin < 0)
> + return;
> +
> + mux = sunxi_gpio_get_cfgpin(pin);
> + sunxi_gpio_set_cfgpin(pin, SUNXI_GPIO_INPUT);
...
> + sunxi_gpio_set_pull(pin, SUNXI_GPIO_PULL_UP);
it seems this doesn't work for me.
while I'm testing on A527, using pin PD6 (GPIO4_D6 in schematic)
it goes directly to FEL mode, not sure if I setup things wrong..
CONFIG_SUNXI_FAKE_FEL_PIN="PD6"
> + value = gpio_get_value(pin);
> + sunxi_gpio_set_cfgpin(pin, mux);
> +
> + if (value)
> + return;
> +
> + /* Older SoCs maps the BootROM high in the address space. */
> + if (fel_stash.sctlr & BIT(13))
> + brom_entry |= 0xffff0000;
> +
> + return_to_fel(0, brom_entry);
> +}
> +
> void board_init_f(ulong dummy)
> {
> + check_fake_fel_button();
> +
this isn't a problem, I can understand calling it here will make board
enter FEL mode as early as possible..
just wondering if better to move this function after preloader_console_init(),
and log out a message to let user know explicitly - entering FEL mode from SPL..
(I personally find it helpful)
but, if you prefer not to change, then fine by me..
> sunxi_sram_init();
>
> /* Enable non-secure access to some peripherals */
> --
> 2.46.3
>
--
Yixun Lan (dlan)
