diff options
author | Julius Werner <jwerner@chromium.org> | 2019-08-12 16:45:21 -0700 |
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committer | Patrick Georgi <pgeorgi@google.com> | 2019-08-22 10:36:22 +0000 |
commit | db7f6fb75282a305c2b0f5540d2f7be939f20dde (patch) | |
tree | 2c4fc9e51c6c38c9d7a10a91083c961fd914471e /payloads/libpayload | |
parent | 54ff1a0ad3bb3c1c4bc5283aaf2f03b17c3b25f1 (diff) | |
download | coreboot-db7f6fb75282a305c2b0f5540d2f7be939f20dde.tar.xz |
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>
Diffstat (limited to 'payloads/libpayload')
-rw-r--r-- | payloads/libpayload/include/libpayload.h | 19 | ||||
-rw-r--r-- | payloads/libpayload/libc/lib.c | 52 |
2 files changed, 71 insertions, 0 deletions
diff --git a/payloads/libpayload/include/libpayload.h b/payloads/libpayload/include/libpayload.h index 57a3afc6b1..80bfaae6bf 100644 --- a/payloads/libpayload/include/libpayload.h +++ b/payloads/libpayload/include/libpayload.h @@ -446,6 +446,25 @@ static inline int __ffs(u32 x) { return log2(x & (u32)(-(s32)x)); } /** + * @defgroup mmio MMIO helper functions + * @{ + */ +#if !CONFIG(LP_ARCH_MIPS) +void buffer_from_fifo32(void *buffer, size_t size, void *fifo, + int fifo_stride, int fifo_width); +void buffer_to_fifo32_prefix(void *buffer, u32 prefix, int prefsz, size_t size, + void *fifo, int fifo_stride, int fifo_width); +static inline void buffer_to_fifo32(void *buffer, size_t size, void *fifo, + int fifo_stride, int fifo_width) +{ + buffer_to_fifo32_prefix(buffer, size, 0, 0, fifo, + fifo_stride, fifo_width); +} +#endif +/** @} */ + + +/** * @defgroup hash Hashing functions * @{ */ diff --git a/payloads/libpayload/libc/lib.c b/payloads/libpayload/libc/lib.c index bead1f801b..081d7dd0e2 100644 --- a/payloads/libpayload/libc/lib.c +++ b/payloads/libpayload/libc/lib.c @@ -27,6 +27,7 @@ * SUCH DAMAGE. */ +#include <assert.h> #include <libpayload.h> /* @@ -125,3 +126,54 @@ char *getenv(const char *name) { return NULL; } + +#if !CONFIG(LP_ARCH_MIPS) +/* + * Reads a transfer buffer from 32-bit FIFO registers. fifo_stride is the + * distance in bytes between registers (e.g. pass 4 for a normal array of 32-bit + * registers or 0 to read everything from the same register). fifo_width is + * the amount of bytes read per register (can be 1 through 4). + */ +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)); + } +} + +/* + * Version of buffer_to_fifo32() that can prepend a prefix of up to fifo_width + * size to the transfer. This is often useful for protocols where a command word + * precedes the actual payload data. The prefix must be packed in the low-order + * bytes of the 'prefix' u32 parameter and any high-order bytes exceeding prefsz + * must be 0. Note that 'size' counts total bytes written, including 'prefsz'. + */ +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; + } + +} +#endif |