db7f6fb752
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 <jwerner@chromium.org> Reviewed-on: https://review.coreboot.org/c/coreboot/+/34850 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Patrick Georgi <pgeorgi@google.com>
55 lines
1.5 KiB
C
55 lines
1.5 KiB
C
/*
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* This file is part of the coreboot project.
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*
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* Copyright 2019 Google LLC
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <assert.h>
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#include <device/mmio.h>
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/* Helper functions for various MMIO access patterns. */
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void buffer_from_fifo32(void *buffer, size_t size, void *fifo,
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int fifo_stride, int fifo_width)
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{
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u8 *p = buffer;
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int i, j;
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assert(fifo_width > 0 && fifo_width <= sizeof(u32) &&
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fifo_stride % sizeof(u32) == 0);
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for (i = 0; i < size; i += fifo_width, fifo += fifo_stride) {
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u32 val = read32(fifo);
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for (j = 0; j < MIN(size - i, fifo_width); j++)
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*p++ = (u8)(val >> (j * 8));
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}
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}
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void buffer_to_fifo32_prefix(void *buffer, u32 prefix, int prefsz, size_t size,
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void *fifo, int fifo_stride, int fifo_width)
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{
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u8 *p = buffer;
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int i, j = prefsz;
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assert(fifo_width > 0 && fifo_width <= sizeof(u32) &&
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fifo_stride % sizeof(u32) == 0 && prefsz <= fifo_width);
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uint32_t val = prefix;
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for (i = 0; i < size; i += fifo_width, fifo += fifo_stride) {
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for (; j < MIN(size - i, fifo_width); j++)
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val |= *p++ << (j * 8);
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write32(fifo, val);
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val = 0;
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j = 0;
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}
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}
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