The CRC functions found in drivers/gpu/drm/display/drm_dp_mst_topology.c may be useful for other non-DRM code that deals with DisplayPort, e.g. v4l2 drivers for DP receivers. Move these functions to /lib. Signed-off-by: Paweł Anikiel <panikiel@xxxxxxxxxx> --- drivers/gpu/drm/display/Kconfig | 1 + drivers/gpu/drm/display/drm_dp_mst_topology.c | 76 ++---------------- include/linux/crc-dp.h | 10 +++ lib/Kconfig | 8 ++ lib/Makefile | 1 + lib/crc-dp.c | 78 +++++++++++++++++++ 6 files changed, 103 insertions(+), 71 deletions(-) create mode 100644 include/linux/crc-dp.h create mode 100644 lib/crc-dp.c diff --git a/drivers/gpu/drm/display/Kconfig b/drivers/gpu/drm/display/Kconfig index 09712b88a5b8..c615f50152f2 100644 --- a/drivers/gpu/drm/display/Kconfig +++ b/drivers/gpu/drm/display/Kconfig @@ -14,6 +14,7 @@ config DRM_DISPLAY_HELPER config DRM_DISPLAY_DP_HELPER bool depends on DRM_DISPLAY_HELPER + select CRC_DP help DRM display helpers for DisplayPort. diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c index f7c6b60629c2..ada1f90fa808 100644 --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c @@ -22,6 +22,7 @@ #include <linux/bitfield.h> #include <linux/delay.h> +#include <linux/crc-dp.h> #include <linux/errno.h> #include <linux/i2c.h> #include <linux/init.h> @@ -195,73 +196,6 @@ drm_dp_mst_rad_to_str(const u8 rad[8], u8 lct, char *out, size_t len) } /* sideband msg handling */ -static u8 drm_dp_msg_header_crc4(const uint8_t *data, size_t num_nibbles) -{ - u8 bitmask = 0x80; - u8 bitshift = 7; - u8 array_index = 0; - int number_of_bits = num_nibbles * 4; - u8 remainder = 0; - - while (number_of_bits != 0) { - number_of_bits--; - remainder <<= 1; - remainder |= (data[array_index] & bitmask) >> bitshift; - bitmask >>= 1; - bitshift--; - if (bitmask == 0) { - bitmask = 0x80; - bitshift = 7; - array_index++; - } - if ((remainder & 0x10) == 0x10) - remainder ^= 0x13; - } - - number_of_bits = 4; - while (number_of_bits != 0) { - number_of_bits--; - remainder <<= 1; - if ((remainder & 0x10) != 0) - remainder ^= 0x13; - } - - return remainder; -} - -static u8 drm_dp_msg_data_crc4(const uint8_t *data, u8 number_of_bytes) -{ - u8 bitmask = 0x80; - u8 bitshift = 7; - u8 array_index = 0; - int number_of_bits = number_of_bytes * 8; - u16 remainder = 0; - - while (number_of_bits != 0) { - number_of_bits--; - remainder <<= 1; - remainder |= (data[array_index] & bitmask) >> bitshift; - bitmask >>= 1; - bitshift--; - if (bitmask == 0) { - bitmask = 0x80; - bitshift = 7; - array_index++; - } - if ((remainder & 0x100) == 0x100) - remainder ^= 0xd5; - } - - number_of_bits = 8; - while (number_of_bits != 0) { - number_of_bits--; - remainder <<= 1; - if ((remainder & 0x100) != 0) - remainder ^= 0xd5; - } - - return remainder & 0xff; -} static inline u8 drm_dp_calc_sb_hdr_size(struct drm_dp_sideband_msg_hdr *hdr) { u8 size = 3; @@ -284,7 +218,7 @@ static void drm_dp_encode_sideband_msg_hdr(struct drm_dp_sideband_msg_hdr *hdr, (hdr->msg_len & 0x3f); buf[idx++] = (hdr->somt << 7) | (hdr->eomt << 6) | (hdr->seqno << 4); - crc4 = drm_dp_msg_header_crc4(buf, (idx * 2) - 1); + crc4 = crc_dp_msg_header(buf, (idx * 2) - 1); buf[idx - 1] |= (crc4 & 0xf); *len = idx; @@ -305,7 +239,7 @@ static bool drm_dp_decode_sideband_msg_hdr(const struct drm_dp_mst_topology_mgr len += ((buf[0] & 0xf0) >> 4) / 2; if (len > buflen) return false; - crc4 = drm_dp_msg_header_crc4(buf, (len * 2) - 1); + crc4 = crc_dp_msg_header(buf, (len * 2) - 1); if ((crc4 & 0xf) != (buf[len - 1] & 0xf)) { drm_dbg_kms(mgr->dev, "crc4 mismatch 0x%x 0x%x\n", crc4, buf[len - 1]); @@ -725,7 +659,7 @@ static void drm_dp_crc_sideband_chunk_req(u8 *msg, u8 len) { u8 crc4; - crc4 = drm_dp_msg_data_crc4(msg, len); + crc4 = crc_dp_msg_data(msg, len); msg[len] = crc4; } @@ -782,7 +716,7 @@ static bool drm_dp_sideband_append_payload(struct drm_dp_sideband_msg_rx *msg, if (msg->curchunk_idx >= msg->curchunk_len) { /* do CRC */ - crc4 = drm_dp_msg_data_crc4(msg->chunk, msg->curchunk_len - 1); + crc4 = crc_dp_msg_data(msg->chunk, msg->curchunk_len - 1); if (crc4 != msg->chunk[msg->curchunk_len - 1]) print_hex_dump(KERN_DEBUG, "wrong crc", DUMP_PREFIX_NONE, 16, 1, diff --git a/include/linux/crc-dp.h b/include/linux/crc-dp.h new file mode 100644 index 000000000000..b63435c82b96 --- /dev/null +++ b/include/linux/crc-dp.h @@ -0,0 +1,10 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_CRC_DP_H +#define _LINUX_CRC_DP_H + +#include <linux/types.h> + +u8 crc_dp_msg_header(const uint8_t *data, size_t num_nibbles); +u8 crc_dp_msg_data(const uint8_t *data, u8 number_of_bytes); + +#endif /* _LINUX_CRC_DP_H */ diff --git a/lib/Kconfig b/lib/Kconfig index 5ddda7c2ed9b..28f9f6cfec9f 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -171,6 +171,14 @@ config CRC_ITU_T the kernel tree does. Such modules that use library CRC ITU-T V.41 functions require M here. +config CRC_DP + tristate "CRC DisplayPort MST functions" + help + This option is provided for the case where no in-kernel-tree + modules require CRC DisplayPort MST functions, but a module built outside + the kernel tree does. Such modules that use library CRC DisplayPort MST + functions require M here. + config CRC32 tristate "CRC32/CRC32c functions" default y diff --git a/lib/Makefile b/lib/Makefile index 6b09731d8e61..e4d7ffa260b3 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -188,6 +188,7 @@ obj-$(CONFIG_CRC7) += crc7.o obj-$(CONFIG_LIBCRC32C) += libcrc32c.o obj-$(CONFIG_CRC8) += crc8.o obj-$(CONFIG_CRC64_ROCKSOFT) += crc64-rocksoft.o +obj-$(CONFIG_CRC_DP) += crc-dp.o obj-$(CONFIG_XXHASH) += xxhash.o obj-$(CONFIG_GENERIC_ALLOCATOR) += genalloc.o diff --git a/lib/crc-dp.c b/lib/crc-dp.c new file mode 100644 index 000000000000..95b58bc436d4 --- /dev/null +++ b/lib/crc-dp.c @@ -0,0 +1,78 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/crc-dp.h> + +/* + * Sideband MSG Header CRC + * Defined in DisplayPort 1.2 spec, section 2.11.3.1.9 + */ +u8 crc_dp_msg_header(const uint8_t *data, size_t num_nibbles) +{ + u8 bitmask = 0x80; + u8 bitshift = 7; + u8 array_index = 0; + int number_of_bits = num_nibbles * 4; + u8 remainder = 0; + + while (number_of_bits != 0) { + number_of_bits--; + remainder <<= 1; + remainder |= (data[array_index] & bitmask) >> bitshift; + bitmask >>= 1; + bitshift--; + if (bitmask == 0) { + bitmask = 0x80; + bitshift = 7; + array_index++; + } + if ((remainder & 0x10) == 0x10) + remainder ^= 0x13; + } + + number_of_bits = 4; + while (number_of_bits != 0) { + number_of_bits--; + remainder <<= 1; + if ((remainder & 0x10) != 0) + remainder ^= 0x13; + } + + return remainder; +} + +/* + * Sideband MSG Data CRC + * Defined in DisplayPort 1.2 spec, section 2.11.3.2.2 + */ +u8 crc_dp_msg_data(const uint8_t *data, u8 number_of_bytes) +{ + u8 bitmask = 0x80; + u8 bitshift = 7; + u8 array_index = 0; + int number_of_bits = number_of_bytes * 8; + u16 remainder = 0; + + while (number_of_bits != 0) { + number_of_bits--; + remainder <<= 1; + remainder |= (data[array_index] & bitmask) >> bitshift; + bitmask >>= 1; + bitshift--; + if (bitmask == 0) { + bitmask = 0x80; + bitshift = 7; + array_index++; + } + if ((remainder & 0x100) == 0x100) + remainder ^= 0xd5; + } + + number_of_bits = 8; + while (number_of_bits != 0) { + number_of_bits--; + remainder <<= 1; + if ((remainder & 0x100) != 0) + remainder ^= 0xd5; + } + + return remainder & 0xff; +} -- 2.43.0.687.g38aa6559b0-goog