linux-drivers/
drivers/tty/serial

8250/16550 UARTs and SoC/PCIe serial port controllers

Linux's main serial port subsystem, covering the classic 8250/16550 UART found on PC serial ports for decades plus countless SoC, PCIe, and I2C/SPI-bridge UART variants in embedded systems, industrial gear, and server BMC consoles. It powers /dev/ttyS* and the serial consoles still used for headless setup and debugging in 2025.

keep conf=0.95 last_sold=2025 deploy=high replacement=none subsystem=tty category=bus-other
95%

recommendation

It should stay because serial ports remain everywhere: the directory saw roughly 1,400 commits from over 270 authors in the last five years and supports hardware still being sold new, including NXP's SC16IS7xx I2C/SPI UART bridges and Microchip's PCI11101C / PCI1xxxx PCIe UARTs that vendors list as in production with 2025 datasheets. There is no successor subsystem and no plausible replacement; this is core, actively maintained infrastructure.

repository signals

161 files
131,925 source lines
2,094 commits, 5y
+37,390 / −25,381 lines added / removed, 5y
394 authors, 5y
monthly commits · 2021-04-21 → 2026-04-21 · 2,094 total · active in 60/61 months
2021 2022 2023 2024 2025 2026 2021-04: 43 commits · +168 −182 2021-05: 55 commits · +364 −293 2021-06: 33 commits · +1,359 −1,186 2021-07: 23 commits · +200 −135 2021-08: 20 commits · +216 −93 2021-09: 10 commits · +37 −21 2021-10: 30 commits · +550 −323 2021-11: 28 commits · +379 −516 2021-12: 30 commits · +263 −230 2022-01: 27 commits · +279 −221 2022-02: 38 commits · +1,940 −418 2022-03: 37 commits · +852 −641 2022-04: 74 commits · +1,473 −962 2022-05: 56 commits · +383 −530 2022-06: 91 commits · +1,184 −859 2022-07: 35 commits · +633 −1,274 2022-08: 28 commits · +214 −289 2022-09: 42 commits · +432 −474 2022-10: 62 commits · +444 −949 2022-11: 64 commits · +742 −400 2022-12: 28 commits · +531 −316 2023-01: 32 commits · +383 −172 2023-02: 34 commits · +858 −236 2023-03: 35 commits · +213 −162 2023-04: 21 commits · +152 −37 2023-05: 35 commits · +1,202 −335 2023-06: 21 commits · +936 −109 2023-07: 52 commits · +526 −395 2023-08: 52 commits · +639 −683 2023-09: 97 commits · +1,264 −1,265 2023-10: 36 commits · +1,943 −393 2023-11: 77 commits · +328 −458 2023-12: 51 commits · +712 −481 2024-01: 63 commits · +964 −570 2024-02: 28 commits · +318 −205 2024-03: 49 commits · +791 −736 2024-04: 68 commits · +2,547 −1,624 2024-05: 29 commits · +828 −823 2024-06: 20 commits · +212 −215 2024-07: 15 commits · +263 −58 2024-08: 29 commits · +292 −311 2024-09: 17 commits · +248 −96 2024-10: 29 commits · +312 −258 2024-11: 12 commits · +122 −49 2024-12: 23 commits · +383 −288 2025-01: 32 commits · +558 −767 2025-02: 26 commits · +972 −270 2025-03: 30 commits · +1,035 −515 2025-04: 20 commits · +757 −392 2025-05: 5 commits · +29 −31 2025-06: 42 commits · +1,655 −916 2025-07: 19 commits · +472 −341 2025-08: 20 commits · +376 −498 2025-09: 13 commits · +154 −267 2025-10: 27 commits · +1,036 −458 2025-11: 39 commits · +686 −329 2025-12: 8 commits · +33 −26 2026-01: 15 commits · +143 −148 2026-02: 15 commits · +380 −150 2026-03: 2 commits · +18 −0 2026-04: 0 commits · +0 −0

sources

  1. git.kernel.org

    Upstream Kconfig describes this subtree as covering standard 8250/16550 serial support plus many PCI, platform, and bridge-specific variants, indicating it is a broad active serial-driver subsystem rather than a single legacy device driver.

  2. nxp.com

    NXP lists SC16IS740/750/760 UART bridge parts as active and shows a 2025 datasheet, demonstrating hardware covered by this directory is still sold for new designs.

  3. nxp.com

    NXP lists SC16IS752/762 as active dual-UART bridge products, supporting ongoing embedded and industrial deployments for drivers under this subtree.

  4. microchip.com

    Microchip lists PCI11101C as 'In Production'; the directory includes `8250_pci1xxxx.c`, so at least one modern PCIe UART-capable family served here remains current.

  5. microchip.com

    Microchip's 2025 AN5213 states the PCI1xxxx family includes UART peripherals, reinforcing that contemporary PCIe devices still rely on Linux serial support in this subtree.

codex reasoning notes (technical)

Static prompt data already shows very high current upstream activity: 1429 substantive commits in 5y, 274 authors, and most recent touch on 2026-03-12, which is incompatible with deprecation/removal. I attempted lore-first verification via `list_mcp_resources` for `lore-http` and shell `lei`, but the MCP server was unavailable and `lei` was not installed, so no direct lore thread URL could be obtained in this environment. URLs were obtained via `web.search_query` for NXP/Microchip product evidence, plus one canonical-recall kernel.org source-tree URL for subsystem scope. Because this directory covers mainstream 8250/16550 serial, many SoC UARTs, and active bridge/PCIe parts still sold for industrial and embedded use, there is no natural single replacement driver and the correct recommendation is to keep it.