[U-Boot] [PATCH v2] imx_common: check for Serial Downloader in spl_boot_device

[Eric Nelson <eric@nelint.com>]

Hi Stefano,

On 12/11/2015 06:40 AM, Stefano Babic wrote:
> Check for bmode before reading the boot device
> to check if a serial downloader is started,
> and returns UART if the serial downloader is set,
> letting SPL to wait for an image if
> CONFIG_SPL_YMODEM_SUPPORT is set.
> 
> This allows to load again a SPL based board
> with imx_usb_loader together with a tool
> such as kermit.
> 
> Signed-off-by: Stefano Babic <sbabic@denx.de>
> CC: Tim Harvey <tharvey@gateworks.com>
> CC: Fabio Estevam <Fabio.Estevam@freescale.com>
> CC: Eric Nelson <eric.nelson@boundarydevices.com>
> ---
> 
> Changes in v2:
> - Add documentation (S. Roese)
> - Check just bits 24-25 because reserved bits are set on some variants
>   (E. Nelson)
> - Set boot device to UARt if USB is set to let bmode working as
>   suggested by Eric
> 
>  arch/arm/imx-common/spl.c |  8 ++++++++
>  doc/README.imx6           | 51 +++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 59 insertions(+)
> 
> diff --git a/arch/arm/imx-common/spl.c b/arch/arm/imx-common/spl.c
> index ac6e40e..a8f2492 100644
> --- a/arch/arm/imx-common/spl.c
> +++ b/arch/arm/imx-common/spl.c
> @@ -20,7 +20,15 @@ u32 spl_boot_device(void)
>  	struct src *psrc = (struct src *)SRC_BASE_ADDR;
>  	unsigned int gpr10_boot = readl(&psrc->gpr10) & (1 << 28);
>  	unsigned reg = gpr10_boot ? readl(&psrc->gpr9) : readl(&psrc->sbmr1);
> +	unsigned int bmode = readl(&psrc->sbmr2);
>  
> +	/*
> +	 * Check for BMODE if serial downloader is enabled
> +	 * BOOT_MODE - see IMX6DQRM Table 8-1
> +	 */
> +	if ((((bmode >> 24) & 0x03)  == 0x01) || /* Serial Downloader */

I think Marek will have a problem with the yoda conditional:

> +		(gpr10_boot && (1 == reg)))
> +		return BOOT_DEVICE_UART;
>  	/* BOOT_CFG1[7:4] - see IMX6DQRM Table 8-8 */
>  	switch ((reg & 0x000000FF) >> 4) {
>  	 /* EIM: See 8.5.1, Table 8-9 */
> diff --git a/doc/README.imx6 b/doc/README.imx6
> index 437af2f..5aa41f2 100644
> --- a/doc/README.imx6
> +++ b/doc/README.imx6
> @@ -84,3 +84,54 @@ Address:
>  Reading bank 4:
>  
>  Word 0x00000002: 9f027772 00000004
> +
> +2. Using imx_usb_loader for first install with SPL
> +--------------------------------------------------
> +
> +imx_usb_loader is a very nice tool by BoundaryDevice that
> +allow to install U-Boot without a JTAG debugger, using
> +the USB boot mode as described in the manual. It is
> +a replacement for Freescale's MFGTOOLS.
> +
> +The sources can be found here:
> +
> +	https://github.com/boundarydevices/imx_usb_loader.git
> +
> +Booting in USB mode, the i.MX6 announces itself to the Linux Host as:
> +
> +Bus 001 Device 111: ID 15a2:0061 Freescale Semiconductor, Inc.
> +
> +imx_usb_loader is able to download a single file (u-boot.imx)
> +to the board. For boards without SPL support, it is enough to
> +issue the command:
> +
> +	sudo ../imx_usb_loader/imx_usb -v u-boot.imx
> +

s/requires to use two communications/requires two downloads/

> +Getting U-Boot when SPL support is active, it requires to use
> +two communications. imx_usb_loader downloads the SPL into
> +OCRAM and starts it. SPL will check for a valid u-boot.img, and
> +because it is not found, it will wait for it using the y-modem
> +protocol via the console.
> +

I think "by combining" would be clearer:

> +A first install is then possible combining imx_usb_loader with
> +another tool such as kermit.
> +
> +sudo ../imx_usb_loader/imx_usb -v SPL
> +kermit kermit_uboot
> +
> +and kermit_uboot contains something like this (set line should be adjusted):
> +
> +set line /dev/ttyUSB1
> +set speed 115200
> +SET CARRIER-WATCH OFF
> +set flow-control none
> +set handshake none
> +set prefixing all
> +set file type bin
> +set protocol ymodem
> +send u-boot.img
> +c
> +
> +The last "c" command tells kermit (from ckermit package in most distros)
> +to switch from command line mode to communication mode, and when the
> +script is finished, the U-Boot prompt is shown in the same shell.
> 

By the way, besides the couple of nit-picks above, this documentation is
really nice!

Otherwise:

Reviewed-By: Eric Nelson <eric@nelint.com>
Tested-By: Eric Nelson <eric@nelint.com>