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Wed, 19 Aug 2026 22:06:53 -0700 (PDT) From: Jinseob Kim To: jic23@kernel.org, linux-iio@vger.kernel.org Cc: dlechner@baylibre.com, nuno.sa@analog.com, andy@kernel.org, linux-kernel@vger.kernel.org, rdunlap@infradead.org, joshua.crofts1@gmail.com, u.kleine-koenig@baylibre.com, julianbraha@gmail.com, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, grondon@gmail.com, devicetree@vger.kernel.org, corbet@lwn.net, skhan@linuxfoundation.org, linux-doc@vger.kernel.org Subject: [PATCH v8 3/5] iio: osf: add protocol decoding Date: Thu, 20 Aug 2026 14:06:06 +0900 Message-ID: <20260820050608.5440-4-kimjinseob88@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260820050608.5440-1-kimjinseob88@gmail.com> References: <20260820050608.5440-1-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 helpers for decoding Open Sensor Fusion frame headers and supported message payloads. The decoder validates framing, payload bounds and CRC before exposing decoded frame contents to the rest of the driver. Framing validation includes the OSF0 wire magic and fixed header length. Protocol version and reserved header fields are exposed to the core so authenticated-frame policy is handled after CRC validation. Capability entries are decoded structurally, including their flags and reserved fields. The core can then apply support policy without rejecting an entire report solely because it contains future entry values. Use explicit little-endian wire storage sizes and designated initializers for decoded output structures. Signed-off-by: Jinseob Kim --- MAINTAINERS | 1 + drivers/iio/opensensorfusion/osf_protocol.c | 224 ++++++++++++++++++++ drivers/iio/opensensorfusion/osf_protocol.h | 101 +++++++++ 3 files changed, 326 insertions(+) create mode 100644 drivers/iio/opensensorfusion/osf_protocol.c create mode 100644 drivers/iio/opensensorfusion/osf_protocol.h diff --git a/MAINTAINERS b/MAINTAINERS index 9550cf1900bd..76fa860a7b91 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -20298,6 +20298,7 @@ M: Jinseob Kim S: Maintained F: Documentation/devicetree/bindings/iio/opensensorfusion,osf.yaml F: Documentation/iio/open-sensor-fusion.rst +F: drivers/iio/opensensorfusion/osf_protocol.* K: opensensorfusion OPENCOMPUTE PTP CLOCK DRIVER diff --git a/drivers/iio/opensensorfusion/osf_protocol.c b/drivers/iio/opensensorfusion/osf_protocol.c new file mode 100644 index 000000000000..cd7b8587f737 --- /dev/null +++ b/drivers/iio/opensensorfusion/osf_protocol.c @@ -0,0 +1,224 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include +#include +#include +#include +#include + +#include "osf_protocol.h" + +#define OSF_CRC32_INIT GENMASK(31, 0) +#define OSF_CRC32_XOROUT GENMASK(31, 0) + +static bool osf_sensor_type_valid(u16 sensor_type) +{ + return sensor_type >= OSF_SENSOR_ACCELEROMETER && + sensor_type <= OSF_SENSOR_PROXIMITY; +} + +static u32 osf_crc32_ieee(const u8 *buf, size_t len) +{ + return crc32_le(OSF_CRC32_INIT, buf, len) ^ OSF_CRC32_XOROUT; +} + +int osf_protocol_decode_frame(const u8 *buf, size_t len, + struct osf_frame *frame, size_t *frame_len) +{ + u32 expected_crc; + u32 actual_crc; + u32 payload_len; + size_t total_len; + + if (!buf || !frame || !frame_len) + return -EINVAL; + + if (len < OSF_FRAME_MIN_LEN) + return -EMSGSIZE; + + if (get_unaligned_le32(buf) != OSF_FRAME_MAGIC) + return -EPROTO; + + if (get_unaligned_le16(buf + 6) != OSF_FRAME_HEADER_LEN) + return -EPROTO; + + payload_len = get_unaligned_le32(buf + 10); + if (payload_len > len - OSF_FRAME_MIN_LEN) + return -EMSGSIZE; + + total_len = OSF_FRAME_HEADER_LEN + payload_len + OSF_FRAME_CRC_LEN; + expected_crc = osf_crc32_ieee(buf, OSF_FRAME_HEADER_LEN + payload_len); + actual_crc = get_unaligned_le32(buf + OSF_FRAME_HEADER_LEN + payload_len); + + if (actual_crc != expected_crc) + return -EBADMSG; + + frame->protocol_major = buf[4]; + frame->protocol_minor = buf[5]; + frame->message_type = get_unaligned_le16(buf + 8); + frame->payload_len = payload_len; + frame->sequence = get_unaligned_le64(buf + 14); + frame->timestamp_us = get_unaligned_le64(buf + 22); + frame->flags = get_unaligned_le32(buf + 30); + frame->reserved = get_unaligned_le32(buf + 34); + frame->payload = buf + OSF_FRAME_HEADER_LEN; + frame->crc = actual_crc; + *frame_len = total_len; + + return 0; +} + +int osf_protocol_decode_sensor_sample(const struct osf_frame *frame, + struct osf_sensor_sample *sample) +{ + u16 channel_count; + u16 sample_format; + u16 sensor_type; + size_t expected_len; + const u8 *payload; + + if (!frame || !sample || !frame->payload) + return -EINVAL; + + if (frame->message_type != OSF_MSG_SENSOR_SAMPLE) + return -EPROTO; + + if (frame->payload_len < OSF_SENSOR_SAMPLE_BASE_LEN) + return -EMSGSIZE; + + payload = frame->payload; + sensor_type = get_unaligned_le16(payload); + channel_count = get_unaligned_le16(payload + 4); + sample_format = get_unaligned_le16(payload + 6); + + if (!osf_sensor_type_valid(sensor_type)) + return -EPROTO; + + if (!channel_count) + return -EPROTO; + + if (sample_format != OSF_SAMPLE_FORMAT_S32) + return -EPROTO; + + if (get_unaligned_le32(payload + 12)) + return -EPROTO; + + expected_len = OSF_SENSOR_SAMPLE_BASE_LEN + channel_count * sizeof(__le32); + if (frame->payload_len != expected_len) + return -EMSGSIZE; + + *sample = (struct osf_sensor_sample) { + .sensor_type = sensor_type, + .sensor_index = get_unaligned_le16(payload + 2), + .channel_count = channel_count, + .sample_format = sample_format, + .scale_nano = get_unaligned_le32(payload + 8), + .samples = payload + OSF_SENSOR_SAMPLE_BASE_LEN, + }; + + return 0; +} + +int osf_protocol_sensor_sample_value(const struct osf_sensor_sample *sample, + u16 index, s32 *value) +{ + if (!sample || !sample->samples || !value) + return -EINVAL; + + if (index >= sample->channel_count) + return -ERANGE; + + /* Samples are little-endian two's-complement signed values. */ + *value = get_unaligned_le32(sample->samples + index * sizeof(__le32)); + + return 0; +} + +int osf_protocol_decode_device_status(const struct osf_frame *frame, + struct osf_device_status *status) +{ + const u8 *payload; + + if (!frame || !status || !frame->payload) + return -EINVAL; + + if (frame->message_type != OSF_MSG_DEVICE_STATUS) + return -EPROTO; + + if (frame->payload_len != OSF_DEVICE_STATUS_LEN) + return -EMSGSIZE; + + payload = frame->payload; + if (get_unaligned_le32(payload + 16)) + return -EPROTO; + + *status = (struct osf_device_status) { + .uptime_s = get_unaligned_le32(payload), + .status_flags = get_unaligned_le32(payload + 4), + .error_flags = get_unaligned_le32(payload + 8), + .dropped_frames = get_unaligned_le32(payload + 12), + }; + + return 0; +} + +int osf_protocol_decode_capability_report(const struct osf_frame *frame, + struct osf_capability_report *report) +{ + u16 capability_count; + size_t expected_len; + const u8 *payload; + + if (!frame || !report || !frame->payload) + return -EINVAL; + + if (frame->message_type != OSF_MSG_CAPABILITY_REPORT) + return -EPROTO; + + if (frame->payload_len < OSF_CAP_REPORT_BASE_LEN) + return -EMSGSIZE; + + payload = frame->payload; + capability_count = get_unaligned_le16(payload); + + if (get_unaligned_le16(payload + 2)) + return -EPROTO; + + expected_len = OSF_CAP_REPORT_BASE_LEN + + capability_count * OSF_CAP_SENSOR_ENTRY_LEN; + if (frame->payload_len != expected_len) + return -EMSGSIZE; + + *report = (struct osf_capability_report) { + .capability_count = capability_count, + .entries = payload + OSF_CAP_REPORT_BASE_LEN, + }; + + return 0; +} + +int osf_protocol_decode_capability_entry(const struct osf_capability_report + *report, u16 index, + struct osf_capability_entry *entry) +{ + const u8 *payload; + + if (!report || !report->entries || !entry) + return -EINVAL; + + if (index >= report->capability_count) + return -ERANGE; + + payload = report->entries + index * OSF_CAP_SENSOR_ENTRY_LEN; + *entry = (struct osf_capability_entry) { + .sensor_type = get_unaligned_le16(payload), + .sensor_index = get_unaligned_le16(payload + 2), + .channel_count = get_unaligned_le16(payload + 4), + .sample_format = get_unaligned_le16(payload + 6), + .scale_nano = get_unaligned_le32(payload + 8), + .flags = get_unaligned_le32(payload + 12), + .reserved = get_unaligned_le32(payload + 16), + }; + + return 0; +} diff --git a/drivers/iio/opensensorfusion/osf_protocol.h b/drivers/iio/opensensorfusion/osf_protocol.h new file mode 100644 index 000000000000..2b616f2d5197 --- /dev/null +++ b/drivers/iio/opensensorfusion/osf_protocol.h @@ -0,0 +1,101 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef _OSF_PROTOCOL_H +#define _OSF_PROTOCOL_H + +#include +#include + +#define OSF_PROTOCOL_MAJOR 0 +#define OSF_PROTOCOL_MINOR 0 +#define OSF_FRAME_HEADER_LEN 38 +#define OSF_FRAME_CRC_LEN 4 +#define OSF_FRAME_MIN_LEN (OSF_FRAME_HEADER_LEN + OSF_FRAME_CRC_LEN) +#define OSF_FRAME_MAGIC 0x3046534f /* "OSF0", little-endian */ + +#define OSF_SENSOR_SAMPLE_BASE_LEN 16 +#define OSF_DEVICE_STATUS_LEN 20 +#define OSF_CAP_REPORT_BASE_LEN 4 +#define OSF_CAP_SENSOR_ENTRY_LEN 20 +#define OSF_CAPABILITY_FLAGS_MASK GENMASK(1, 0) + +enum osf_message_type { + OSF_MSG_SENSOR_SAMPLE = 0x0001, + OSF_MSG_DEVICE_STATUS = 0x0002, + OSF_MSG_CAPABILITY_REPORT = 0x0003, +}; + +enum osf_sensor_type { + OSF_SENSOR_ACCELEROMETER = 0x0001, + OSF_SENSOR_GYROSCOPE = 0x0002, + OSF_SENSOR_MAGNETOMETER = 0x0003, + OSF_SENSOR_BAROMETER = 0x0004, + OSF_SENSOR_TEMPERATURE = 0x0005, + OSF_SENSOR_HUMIDITY = 0x0006, + OSF_SENSOR_AMBIENT_LIGHT = 0x0007, + OSF_SENSOR_PROXIMITY = 0x0008, +}; + +enum osf_sample_format { + OSF_SAMPLE_FORMAT_S32 = 0x0001, +}; + +struct osf_frame { + u8 protocol_major; + u8 protocol_minor; + u16 message_type; + u32 payload_len; + u64 sequence; + u64 timestamp_us; + u32 flags; + u32 reserved; + /* payload points into the caller-owned frame buffer. */ + const u8 *payload; + u32 crc; +}; + +struct osf_sensor_sample { + u16 sensor_type; + u16 sensor_index; + u16 channel_count; + u16 sample_format; + u32 scale_nano; + const u8 *samples; +}; + +struct osf_device_status { + u32 uptime_s; + u32 status_flags; + u32 error_flags; + u32 dropped_frames; +}; + +struct osf_capability_report { + u16 capability_count; + const u8 *entries; +}; + +struct osf_capability_entry { + u16 sensor_type; + u16 sensor_index; + u16 channel_count; + u16 sample_format; + u32 scale_nano; + u32 flags; + u32 reserved; +}; + +int osf_protocol_decode_frame(const u8 *buf, size_t len, + struct osf_frame *frame, size_t *frame_len); +int osf_protocol_decode_sensor_sample(const struct osf_frame *frame, + struct osf_sensor_sample *sample); +int osf_protocol_decode_device_status(const struct osf_frame *frame, + struct osf_device_status *status); +int osf_protocol_decode_capability_report(const struct osf_frame *frame, + struct osf_capability_report *report); +int osf_protocol_decode_capability_entry(const struct osf_capability_report + *report, u16 index, + struct osf_capability_entry *entry); +int osf_protocol_sensor_sample_value(const struct osf_sensor_sample *sample, + u16 index, s32 *value); + +#endif -- 2.43.0