The SRC general purpose registers of the i.MX6 keep their values after a warm reset and are used for communication between the BootROM and upper level software.
SRC_GPR9 allows software override of SRC_SBMR1, e.g. to boot via serial download protocol. Define a suitable syscon-reboot-mode node to use it. To have SRC_GPR9 take effect, bit 28 in SRC_GPR10 has to be set as well. To support this, we use the backward-compatible barebox-specific binding for having multiple 32-bit values for a single mode. This node will _not_ be fixed up into the kernel device tree due to the barebox-specific compatible, but as with all reboot mode storage, the referenced locations will be cleared to the normal (here all-zero) mode. User software that expects exclusive access to GPR9 while GPR10 bit 28 is zero will be broken. Rebooting into serial download is now possible via: barebox@board:/ gpr.reboot_mode.next=serial reset Signed-off-by: Ahmad Fatoum <[email protected]> --- arch/arm/dts/imx6qdl.dtsi | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/arch/arm/dts/imx6qdl.dtsi b/arch/arm/dts/imx6qdl.dtsi index 828be9ce0dbb..c3e02d2117b3 100644 --- a/arch/arm/dts/imx6qdl.dtsi +++ b/arch/arm/dts/imx6qdl.dtsi @@ -6,5 +6,26 @@ pwm2 = &pwm3; pwm3 = &pwm4; ipu0 = &ipu1; + gpr.reboot_mode = &reboot_mode_gpr; + }; +}; + +&src { + compatible = "fsl,imx6q-src", "fsl,imx51-src", "syscon", "simple-mfd"; + + reboot_mode_gpr: reboot-mode { + compatible = "barebox,syscon-reboot-mode"; + offset = <0x40>, <0x44>; /* SRC_GPR{9,10} */ + mask = <0xffffffff>, <0x10000000>; + mode-normal = <0>, <0>; + mode-serial = <0x00000010>, <0x10000000>; + mode-spi0-0 = <0x08000030>, <0x10000000>; + mode-spi0-1 = <0x18000030>, <0x10000000>; + mode-spi0-2 = <0x28000030>, <0x10000000>; + mode-spi0-3 = <0x38000030>, <0x10000000>; + mode-mmc0 = <0x00002040>, <0x10000000>; + mode-mmc1 = <0x00002840>, <0x10000000>; + mode-mmc2 = <0x00003040>, <0x10000000>; + mode-mmc3 = <0x00003840>, <0x10000000>; }; }; -- 2.28.0 _______________________________________________ barebox mailing list [email protected] http://lists.infradead.org/mailman/listinfo/barebox
