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

[Stefano Babic]

Hi Eric,


On 11/12/2015 15:40, Eric Nelson wrote:
> 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 at denx.de>
>> CC: Tim Harvey <tharvey at gateworks.com>
>> CC: Fabio Estevam <Fabio.Estevam at freescale.com>
>> CC: Eric Nelson <eric.nelson at 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)))

I fix it in V3 before Marek complains :-). I do not like yoda
conditions, too.

>> +		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:

ok, thanks.

> 
>> +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 at nelint.com>
> Tested-By: Eric Nelson <eric at nelint.com>
> 

Regards,
Stefano

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