linux-drivers/
drivers/spi

Serial Peripheral Interface (SPI) bus subsystem

SPI is a simple four-wire serial bus invented by Motorola in the 1980s and ubiquitous in embedded systems. This directory holds the Linux SPI core plus dozens of host-controller drivers that let the kernel talk to flash memory, sensors, small displays, and touch controllers on boards ranging from Raspberry Pi-class hardware to current Microchip SAMA7 and STM32 SoCs.

keep conf=0.97 deploy=high replacement=none subsystem=spi category=bus-other
97%

recommendation

It should stay because SPI is one of the most common low-speed buses in modern hardware, used to wire up flash chips, sensors, displays, and radios on embedded boards from vendors like Apple, AMD, STM32, Microchip, and Rockchip. The subsystem is actively maintained, with new controller drivers and core changes still landing in 2026, and there is no replacement framework on the horizon.

repository signals

182 files
130,747 source lines
2,303 commits, 5y
+59,639 / −22,810 lines added / removed, 5y
460 authors, 5y
monthly commits · 2021-04-21 → 2026-04-21 · 2,303 total · active in 61/61 months
2021 2022 2023 2024 2025 2026 2021-04: 16 commits · +73 −74 2021-05: 58 commits · +665 −432 2021-06: 26 commits · +314 −266 2021-07: 39 commits · +336 −364 2021-08: 24 commits · +1,560 −229 2021-09: 19 commits · +996 −109 2021-10: 29 commits · +726 −368 2021-11: 34 commits · +588 −521 2021-12: 10 commits · +39 −29 2022-01: 44 commits · +1,202 −403 2022-02: 43 commits · +2,201 −478 2022-03: 27 commits · +862 −181 2022-04: 52 commits · +1,969 −487 2022-05: 36 commits · +1,676 −281 2022-06: 53 commits · +1,302 −486 2022-07: 27 commits · +470 −115 2022-08: 30 commits · +1,250 −290 2022-09: 37 commits · +232 −1,348 2022-10: 42 commits · +879 −301 2022-11: 27 commits · +1,436 −72 2022-12: 16 commits · +387 −190 2023-01: 23 commits · +298 −236 2023-02: 44 commits · +1,339 −354 2023-03: 139 commits · +794 −830 2023-04: 26 commits · +1,091 −248 2023-05: 39 commits · +433 −285 2023-06: 26 commits · +1,460 −228 2023-07: 76 commits · +1,069 −1,070 2023-08: 117 commits · +2,439 −2,363 2023-09: 16 commits · +219 −111 2023-10: 9 commits · +459 −27 2023-11: 56 commits · +1,833 −1,619 2023-12: 24 commits · +349 −102 2024-01: 23 commits · +115 −141 2024-02: 79 commits · +1,368 −567 2024-03: 32 commits · +344 −363 2024-04: 50 commits · +1,577 −325 2024-05: 50 commits · +637 −566 2024-06: 23 commits · +177 −106 2024-07: 41 commits · +1,232 −174 2024-08: 33 commits · +202 −152 2024-09: 63 commits · +776 −543 2024-10: 19 commits · +573 −65 2024-11: 20 commits · +1,640 −119 2024-12: 36 commits · +950 −233 2025-01: 15 commits · +182 −164 2025-02: 20 commits · +3,720 −65 2025-03: 28 commits · +668 −177 2025-04: 47 commits · +771 −330 2025-05: 60 commits · +917 −680 2025-06: 34 commits · +894 −275 2025-07: 25 commits · +1,539 −137 2025-08: 44 commits · +161 −163 2025-09: 41 commits · +2,221 −256 2025-10: 47 commits · +1,345 −720 2025-11: 53 commits · +1,201 −423 2025-12: 49 commits · +3,230 −433 2026-01: 44 commits · +1,891 −655 2026-02: 16 commits · +226 −257 2026-03: 25 commits · +126 −175 2026-04: 1 commit · +6 −36

sources

  1. lore.kernel.org

    `drivers/spi/spi.c` was still receiving upstream feature work in April 2026, indicating an actively maintained subsystem rather than a retirement candidate.

  2. docs.kernel.org

    Kernel documentation describes SPI as a first-class Linux subsystem covering controller and protocol drivers, reflecting ongoing supported use across embedded systems.

  3. microchip.com

    Microchip lists the SAMA7G54 MPU as `Status: In Production`; the SAMA7 family is a current Linux-capable embedded platform that uses SPI/QSPI-class storage and peripherals.

codex reasoning notes (technical)

`drivers/spi` is the SPI subsystem directory, with core code plus many active controller/protocol drivers, not a single obsolete leaf. Lore evidence came from `lore_file_timeline` on `drivers/spi/spi.c`, which showed recent 2026 traffic and sustained yearly patch volume; no removal signal was found in the sampled lore checks. The kernel-docs and Microchip URLs were obtained via `web.search_query`. Local inspection of `drivers/spi/Kconfig` showed current platform coverage (for example Apple, AMD, STM32, Microchip, Rockchip, virtio), reinforcing that new deployments remain common. SPI itself is still pervasive in new embedded/industrial designs, so this should be kept; there is no natural replacement driver for the subsystem as a whole.