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b57137dcac
Added config option CONFIG_USB_PD_TX_USES_SPI_MASTER which switches to use SPI master for PD transmit. The advantage of SPI master mode is at the end of the tranmission, we don't have to send any dummy 0 bits. When the option is set, the CPU_CLOCK must be set to 38.4MHz, so that the SPI master can generate the correct clock frequency. BUG=chrome-os-partner:28309 BRANCH=none TEST=Tested by connecting two fruitpies together across CC1. One fruitpie has been modified such that the MISO and MOSI lines are swapped and is running PD TX in SPI master mode with 38.4MHz clock, while the other is running PD TX in SPI slave mode. On EC console ran pd charger on one board and pd dev on other board. Verified that communication works with no errors. Ran for 10 minutes in each configuration. Change-Id: Ib24030d34d95d59f4ac6c2dae98bf7adda1ada01 Signed-off-by: Alec Berg <alecaberg@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/197215 Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
In the most general case, the flash layout looks something like this: +---------------------+ | Reserved for EC use | +---------------------+ +---------------------+ | Vblock B | +---------------------+ | RW firmware B | +---------------------+ +---------------------+ | Vblock A | +---------------------+ | RW firmware A | +---------------------+ +---------------------+ | FMAP | +---------------------+ | Public root key | +---------------------+ | Read-only firmware | +---------------------+ BIOS firmware (and kernel) put the vblock info at the start of each image where it's easy to find. The Blizzard EC expects the firmware vector table to come first, so we have to put the vblock at the end. This means we have to know where to look for it, but that's built into the FMAP and the RO firmware anyway, so that's not an issue. The RO firmware doesn't need a vblock of course, but it does need some reserved space for vboot-related things. Using SHA256/RSA4096, the vblock is 2468 bytes (0x9a4), while the public root key is 1064 bytes (0x428) and the current FMAP is 644 bytes (0x284). If we reserve 4K at the top of each FW image, that should give us plenty of room for vboot-related stuff.