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Tue, 16 Jun 2026 00:23:27 -0700 (PDT) From: Jinseob Kim To: Jonathan Cameron , Rob Herring , Krzysztof Kozlowski , Conor Dooley Cc: David Lechner , =?UTF-8?q?Nuno=20S=C3=A1?= , Andy Shevchenko , Jonathan Corbet , Shuah Khan , linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Jinseob Kim Subject: [PATCH RFC v5 4/6] iio: osf: add stream parser Date: Tue, 16 Jun 2026 16:22:40 +0900 Message-ID: <20260616072242.3942-5-kimjinseob88@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260616072242.3942-1-kimjinseob88@gmail.com> References: <20260616072242.3942-1-kimjinseob88@gmail.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add a byte-stream parser that resynchronizes on OSF frame magic, validates complete frames, and forwards decoded frames to the OSF core. Signed-off-by: Jinseob Kim --- drivers/iio/opensensorfusion/osf_stream.c | 187 ++++++++++++++++++++++ drivers/iio/opensensorfusion/osf_stream.h | 31 ++++ 2 files changed, 218 insertions(+) create mode 100644 drivers/iio/opensensorfusion/osf_stream.c create mode 100644 drivers/iio/opensensorfusion/osf_stream.h diff --git a/drivers/iio/opensensorfusion/osf_stream.c b/drivers/iio/opensensorfusion/osf_stream.c new file mode 100644 index 000000000..957f73716 --- /dev/null +++ b/drivers/iio/opensensorfusion/osf_stream.c @@ -0,0 +1,187 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include +#include +#include +#include + +#include "osf_core.h" +#include "osf_protocol.h" +#include "osf_stream.h" + +#define OSF_STREAM_MAGIC_LEN 4 +#define OSF_STREAM_MAX_PAYLOAD_LEN \ + (OSF_STREAM_MAX_FRAME_LEN - OSF_FRAME_HEADER_LEN - OSF_FRAME_CRC_LEN) + +static const u8 osf_stream_magic[OSF_STREAM_MAGIC_LEN] = { + 'O', 'S', 'F', '0', +}; + +static void osf_stream_discard(struct osf_stream *stream, size_t count) +{ + if (count >= stream->len) { + stream->len = 0; + return; + } + + memmove(stream->buf, stream->buf + count, stream->len - count); + stream->len -= count; +} + +static void osf_stream_drop_invalid_head(struct osf_stream *stream) +{ + osf_stream_discard(stream, 1); +} + +static bool osf_stream_magic_match(const u8 *buf, size_t len) +{ + return !memcmp(buf, osf_stream_magic, len); +} + +static size_t osf_stream_discard_to_magic(struct osf_stream *stream) +{ + size_t old_len = stream->len; + size_t match_len; + size_t i; + + for (i = 0; i < stream->len; i++) { + match_len = stream->len - i; + if (match_len > OSF_STREAM_MAGIC_LEN) + match_len = OSF_STREAM_MAGIC_LEN; + + if (osf_stream_magic_match(stream->buf + i, match_len)) { + if (i) + osf_stream_discard(stream, i); + return i; + } + } + + stream->len = 0; + return old_len; +} + +static int osf_stream_process(struct osf_stream *stream) +{ + size_t discarded; + size_t frame_len; + u32 payload_len; + int first_err = 0; + int ret; + + while (stream->len) { + discarded = osf_stream_discard_to_magic(stream); + if (discarded) { + stream->stats.bad_magic_resyncs++; + stream->stats.dropped_bytes += discarded; + if (!first_err) + first_err = -EPROTO; + } + + if (!stream->len) + break; + + if (stream->len < OSF_FRAME_HEADER_LEN) + break; + + if (get_unaligned_le16(stream->buf + 6) != + OSF_FRAME_HEADER_LEN) { + stream->stats.dropped_bytes++; + osf_stream_drop_invalid_head(stream); + if (!first_err) + first_err = -EPROTO; + continue; + } + + payload_len = get_unaligned_le32(stream->buf + 10); + if (payload_len > OSF_STREAM_MAX_PAYLOAD_LEN) { + stream->stats.dropped_bytes++; + osf_stream_drop_invalid_head(stream); + if (!first_err) + first_err = -EMSGSIZE; + continue; + } + + frame_len = OSF_FRAME_HEADER_LEN + payload_len + OSF_FRAME_CRC_LEN; + if (stream->len < frame_len) + break; + + ret = osf_core_receive_frame(stream->osf, stream->buf, frame_len); + if (ret) { + if (ret == -EBADMSG) { + stream->stats.bad_crc_frames++; + stream->stats.dropped_bytes++; + osf_stream_drop_invalid_head(stream); + } else { + osf_stream_discard(stream, frame_len); + } + if (!first_err) + first_err = ret; + continue; + } + + stream->stats.valid_frames++; + osf_stream_discard(stream, frame_len); + } + + return first_err; +} + +void osf_stream_init(struct osf_stream *stream, struct osf_device *osf) +{ + if (!stream) + return; + + stream->osf = osf; + stream->len = 0; + memset(&stream->stats, 0, sizeof(stream->stats)); +} + +void osf_stream_reset(struct osf_stream *stream) +{ + if (stream) { + stream->len = 0; + memset(&stream->stats, 0, sizeof(stream->stats)); + } +} + +int osf_stream_receive_bytes(struct osf_stream *stream, const u8 *buf, + size_t len) +{ + size_t copy_len; + size_t space; + int first_err = 0; + int ret; + + if (!stream || !stream->osf || (!buf && len)) + return -EINVAL; + + if (!len) { + ret = osf_stream_process(stream); + if (ret && !first_err) + first_err = ret; + return first_err; + } + + while (len) { + space = OSF_STREAM_MAX_FRAME_LEN - stream->len; + if (!space) { + stream->stats.dropped_bytes++; + osf_stream_discard(stream, 1); + if (!first_err) + first_err = -EMSGSIZE; + continue; + } + + copy_len = len < space ? len : space; + memcpy(stream->buf + stream->len, buf, copy_len); + stream->len += copy_len; + buf += copy_len; + len -= copy_len; + + ret = osf_stream_process(stream); + if (ret && !first_err) + first_err = ret; + } + + return first_err; +} diff --git a/drivers/iio/opensensorfusion/osf_stream.h b/drivers/iio/opensensorfusion/osf_stream.h new file mode 100644 index 000000000..f7f9477fe --- /dev/null +++ b/drivers/iio/opensensorfusion/osf_stream.h @@ -0,0 +1,31 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef _OSF_STREAM_H +#define _OSF_STREAM_H + +#include + +#define OSF_STREAM_MAX_FRAME_LEN 4096 + +struct osf_device; + +struct osf_stream_stats { + u64 valid_frames; + u64 bad_magic_resyncs; + u64 bad_crc_frames; + u64 partial_frames; + u64 dropped_bytes; +}; + +struct osf_stream { + struct osf_device *osf; + u8 buf[OSF_STREAM_MAX_FRAME_LEN]; + size_t len; + struct osf_stream_stats stats; +}; + +void osf_stream_init(struct osf_stream *stream, struct osf_device *osf); +void osf_stream_reset(struct osf_stream *stream); +int osf_stream_receive_bytes(struct osf_stream *stream, const u8 *buf, + size_t len); + +#endif -- 2.43.0