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 <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>
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@ -445,6 +445,25 @@ static inline int __ffs(u32 x) { return log2(x & (u32)(-(s32)x)); }
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/** @} */
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/**
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* @defgroup mmio MMIO helper functions
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* @{
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*/
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#if !CONFIG(LP_ARCH_MIPS)
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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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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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static inline void buffer_to_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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buffer_to_fifo32_prefix(buffer, size, 0, 0, fifo,
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fifo_stride, fifo_width);
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}
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#endif
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/** @} */
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/**
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* @defgroup hash Hashing functions
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* @{
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@ -27,6 +27,7 @@
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* SUCH DAMAGE.
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*/
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#include <assert.h>
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#include <libpayload.h>
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/*
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@ -125,3 +126,54 @@ char *getenv(const char *name)
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{
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return NULL;
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}
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#if !CONFIG(LP_ARCH_MIPS)
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/*
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* Reads a transfer buffer from 32-bit FIFO registers. fifo_stride is the
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* distance in bytes between registers (e.g. pass 4 for a normal array of 32-bit
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* registers or 0 to read everything from the same register). fifo_width is
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* the amount of bytes read per register (can be 1 through 4).
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*/
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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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/*
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* Version of buffer_to_fifo32() that can prepend a prefix of up to fifo_width
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* size to the transfer. This is often useful for protocols where a command word
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* precedes the actual payload data. The prefix must be packed in the low-order
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* bytes of the 'prefix' u32 parameter and any high-order bytes exceeding prefsz
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* must be 0. Note that 'size' counts total bytes written, including 'prefsz'.
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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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#endif
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@ -53,3 +53,8 @@ verstage-y += i2c.c
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romstage-y += i2c.c
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ramstage-y += i2c.c
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ramstage-y += i2c_bus.c
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bootblock-y += mmio.c
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verstage-y += mmio.c
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romstage-y += mmio.c
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ramstage-y += mmio.c
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@ -0,0 +1,55 @@
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/*
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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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@ -17,5 +17,40 @@
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#include <arch/mmio.h>
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#include <endian.h>
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#include <types.h>
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#endif
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#ifndef __ROMCC__
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/*
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* Reads a transfer buffer from 32-bit FIFO registers. fifo_stride is the
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* distance in bytes between registers (e.g. pass 4 for a normal array of 32-bit
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* registers or 0 to read everything from the same register). fifo_width is
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* the amount of bytes read per register (can be 1 through 4).
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*/
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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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* Version of buffer_to_fifo32() that can prepend a prefix of up to fifo_width
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* size to the transfer. This is often useful for protocols where a command word
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* precedes the actual payload data. The prefix must be packed in the low-order
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* bytes of the 'prefix' u32 parameter and any high-order bytes exceeding prefsz
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* must be 0. Note that 'size' counts total bytes written, including 'prefsz'.
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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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* Writes a transfer buffer into 32-bit FIFO registers. fifo_stride is the
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* distance in bytes between registers (e.g. pass 4 for a normal array of 32-bit
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* registers or 0 to write everything into the same register). fifo_width is
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* the amount of bytes written per register (can be 1 through 4).
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*/
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static inline void buffer_to_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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buffer_to_fifo32_prefix(buffer, size, 0, 0, fifo,
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fifo_stride, fifo_width);
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}
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#endif /* !__ROMCC__ */
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#endif /* __DEVICE_MMIO_H__ */
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