Re: [PATCH v3 00/10] serial: add new I/O type for SPI and I2C bus devices

On Thu, May 21, 2026 at 02:16:46PM -0400, Hugo Villeneuve wrote:
> Hello,
> this patch series add a new I/O type for serial devices on a SPI/I2C bus,
> and a few related cleanups/improvements.
> 
> These changes are based on a suggestion [1] made by Ilpo Järvinen during
> past sc16is7xx driver patches review.
> 
> The first patches make use of uart_iotype_*() functions to simplify and
> cleanup the UART report functions.
> 
> This cleanup sets the stage to avoid displaying irrelevant MMIO or legacy
> I/O information for serial devices on I2C or SPI busses when we add the new
> UPIO_BUS type.
> 
> Tested on a imx6 board with two SC16is752 using SPI mode, and a dummy
> device-tree entry for a MAX3100:
>   dmesg -t | grep "base_baud"
>     2020000.serial: ttymxc0 MMIO:0x02020000 (irq = 197, base_baud = 5000000) is a IMX
>     21e8000.serial: ttymxc1 MMIO:0x021e8000 (irq = 198, base_baud = 5000000) is a IMX
>     spi1.0: ttySC0 (irq = 165, base_baud = 1500000) is a SC16IS752
>     spi1.0: ttySC1 (irq = 165, base_baud = 1500000) is a SC16IS752
>     spi3.0: ttySC2 (irq = 37, base_baud = 1500000) is a SC16IS752
>     spi3.0: ttySC3 (irq = 37, base_baud = 1500000) is a SC16IS752
>     spi3.1: ttyMAX0 (irq = 0, base_baud = 0) is a MAX3100
> Note that before these patches, max3100 silently failed in uart_configure_port()
> because membase/iobase/mapbase were zero.
> 
> For max310x and SC16is7xx in i2c mode, tested only that driver is properly
> registered by using i2c-stub.
> 
> Also tested on a custom board with a Renesas RZ/G2L cpu (sh-sci driver) to
> confirm there is no regression (also with earlycon):
>   dmesg -t | grep "MMIO"
>     earlycon: scif0 MMIO:0x000000001004b800 (options '115200n8')
>     1004b800.serial: ttySC0 MMIO:0x000000001004b800 (irq = 35, base_baud = 0) is a scif
>     1004bc00.serial: ttySC1 MMIO:0x000000001004bc00 (irq = 40, base_baud = 0) is a scif
> 
> Thank you.
> 
> [1] https://lore.kernel.org/lkml/[email protected]/raw
> 
> Link: [v1] https://lore.kernel.org/all/[email protected]/
> Link: [v2] https://lore.kernel.org/all/[email protected]/
> 
> Changes for v3:
> - Rename uart_iotype_legacy_io() -> uart_iotype_io() (Andy)
> - Merge patches 15, 4, 5, 6, 7 and 8
> 
> Changes for v2:
> - Replace snprintf with scnprintf (Ilpo)
> - Fix alignment of : to ? (Ilpo)
> - Move hub6 match port to 8250_hub6.c (Ilpo)
> - earlycon: use uart_iotype_*()
> - 8250_rsa: use uart_iotype_*()
> - 8250_port: use uart_iotype_*() in serial_port_out_sync()
> - simplified uart_line_info() even more and remove intermediate mmio
>   variable
> - Split and rename patch serial: core: prevent irrelevant I/O infos display
>   for UPIO_BUS to serial: core: use uart_iotype_*() to simplify
>   uart_report_port() and moved before UPIO_BUS patch.
> - Add a new patch to implement a function to uniformize the display
>   of I/O infos for uart_report_port(), uart_line_info() and
>   earlycon_print_info(). If accepted could be better integrated/merged with
>   the next series submission. If not, can simply be dropped.
> - Add patch for uart_regiowidth_to_iotype()
> 
> ---
> Hugo Villeneuve (10):
>       serial: 8250_hub6: add hub6_match_port()
>       serial: core: add uart_iotype_mmio/io helper functions
>       serial: core: use uart_iotype_*() to simplify uart_match_port()
>       serial: uniformize serial port I/O infos display
>       serial: 8250: use uart_iotype_*() to simplify code
>       serial: 8250_rsa: use uart_iotype_*() to simplify code
>       serial: core: add new I/O type for SPI and I2C bus devices
>       serial: sc16is7xx: use new UPIO_BUS as iotype
>       serial: max310x: use new UPIO_BUS as iotype
>       serial: max3100: use new UPIO_BUS as iotype
> 
>  drivers/tty/serial/8250/8250.h      |   7 ++
>  drivers/tty/serial/8250/8250_hub6.c |   6 ++
>  drivers/tty/serial/8250/8250_port.c |  43 ++----------
>  drivers/tty/serial/8250/8250_rsa.c  |  40 +++++------
>  drivers/tty/serial/earlycon.c       |  17 ++---
>  drivers/tty/serial/max3100.c        |   1 +
>  drivers/tty/serial/max310x.c        |   9 +--
>  drivers/tty/serial/sc16is7xx.c      |   9 +--
>  drivers/tty/serial/serial_core.c    | 135 +++++++++++++++++++++---------------
>  include/linux/serial_core.h         |   6 ++
>  include/uapi/linux/serial.h         |   1 +
>  11 files changed, 135 insertions(+), 139 deletions(-)

Nice work, all now queued up.

greg k-h