From db7f6fb75282a305c2b0f5540d2f7be939f20dde Mon Sep 17 00:00:00 2001 From: Julius Werner Date: Mon, 12 Aug 2019 16:45:21 -0700 Subject: Add buffer_to/from_fifo32(_prefix) helpers Many peripheral drivers across different SoCs regularly face the same task of piping a transfer buffer into (or reading it out of) a 32-bit FIFO register. Sometimes it's just one register, sometimes a whole array of registers. Sometimes you actually transfer 4 bytes per register read/write, sometimes only 2 (or even 1). Sometimes writes need to be prefixed with one or two command bytes which makes the actual payload buffer "misaligned" in relation to the FIFO and requires a bunch of tricky bit packing logic to get right. Most of the times transfer lengths are not guaranteed to be divisible by 4, which also requires a bunch of logic to treat the potential unaligned end of the transfer correctly. We have a dozen different implementations of this same pattern across coreboot. This patch introduces a new family of helper functions that aims to solve all these use cases once and for all (*fingers crossed*). Change-Id: Ia71f66c1cee530afa4c77c46a838b4de646ffcfb Signed-off-by: Julius Werner Reviewed-on: https://review.coreboot.org/c/coreboot/+/34850 Tested-by: build bot (Jenkins) Reviewed-by: Patrick Georgi --- src/device/mmio.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) create mode 100644 src/device/mmio.c (limited to 'src/device/mmio.c') diff --git a/src/device/mmio.c b/src/device/mmio.c new file mode 100644 index 0000000000..61a1130604 --- /dev/null +++ b/src/device/mmio.c @@ -0,0 +1,55 @@ +/* + * This file is part of the coreboot project. + * + * Copyright 2019 Google LLC + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include +#include + +/* Helper functions for various MMIO access patterns. */ + +void buffer_from_fifo32(void *buffer, size_t size, void *fifo, + int fifo_stride, int fifo_width) +{ + u8 *p = buffer; + int i, j; + + assert(fifo_width > 0 && fifo_width <= sizeof(u32) && + fifo_stride % sizeof(u32) == 0); + + for (i = 0; i < size; i += fifo_width, fifo += fifo_stride) { + u32 val = read32(fifo); + for (j = 0; j < MIN(size - i, fifo_width); j++) + *p++ = (u8)(val >> (j * 8)); + } +} + +void buffer_to_fifo32_prefix(void *buffer, u32 prefix, int prefsz, size_t size, + void *fifo, int fifo_stride, int fifo_width) +{ + u8 *p = buffer; + int i, j = prefsz; + + assert(fifo_width > 0 && fifo_width <= sizeof(u32) && + fifo_stride % sizeof(u32) == 0 && prefsz <= fifo_width); + + uint32_t val = prefix; + for (i = 0; i < size; i += fifo_width, fifo += fifo_stride) { + for (; j < MIN(size - i, fifo_width); j++) + val |= *p++ << (j * 8); + write32(fifo, val); + val = 0; + j = 0; + } + +} -- cgit v1.2.3