[PATCH v4] i2c: add support for the MT7621 I2C controller

[Heiko Schocher]

Hello Justin,

On 27.10.25 14:09, Justin Swartz wrote:
> This commit introduces a port of the Linux kernel's driver for the
> Mediatek's MT7621 I2C controller.
> 
> The port was undertaken as the existing driver intended for Mediatek
> I2C controllers (mtk_i2c.c) is not compatible with the MT7621.
> 
> To use the driver:
> 
>    1.  Ensure that the mode of the i2c pin group is
>        configured for "i2c" rather than "gpio".
> 
>    2.  Delete the existing (bitbanged) i2c node from
>        arch/mips/dts/mt7621.dtsi, or specify:
> 
>          /delete-node/ &i2c;
> 
>    3.  Declare:
> 
>          i2c: i2c at 1e000900 {
>                  compatible = "mediatek,mt7621-i2c";
>                  reg = <0x1e000900 0x100>;
> 
>                  clocks = <&clk50m>;
>                  clock-names = "sys_clock";
> 
>                  resets = <&rstctrl RST_I2C>;
>                  reset-names = "i2c_reset";
> 
>                  pinctrl-names = "default";
>                  pinctrl-0 = <&i2c_pins>;
> 
>                  #address-cells = <1>;
>                  #size-cells = <0>;
>                  status = "okay";
>          };
> 
> Signed-off-by: Justin Swartz <justin.swartz at risingedge.co.za>
> ---
> 
> Notes:
>      [PATCH v4]
>      
>      - Fix style and whitespace issues to appease checkpatch.pl
>      - Include time.h (instead of common.h) for get_timer()
>      - Replace mt7621_i2c_check_ack()'s MMIO register access,
>        via a volatile pointer, with readl() macro expansion.
>      
>      [PATCH v3]
>      
>      - Add an empty line between variable declaration and code to
>        functions that did not have this separation.
>      
>      - Condense multi-line closing brace / else / opening brace
>        sequences into single lines consisting of "} else {" instead.
>      
>      - Relocate mt7621_i2c_check_ack()'s I2C_M_IGNORE_NAK flag check
>        to just after the last variable declaration.
>      
>      [PATCH v2]
>      
>      - Add "REG_" prefix to I2C (Serial Master 0) register definitions.
>      - Remove unused "PINT" (Peripheral Interrupt) register definitions.
>      - Adjust function definition style.
>      
>      - Refactor mt7621_i2c_check_ack() to accept the number of bytes
>        expected to have been acknowledged, instead of accepting a
>        literal value (which represents the acknowledgement status of
>        (up to) 8 bytes, encoded as 8 independent bit values) expected
>        in the SM0_ACK field (bits 23:16) of the SM0CTL1 register.
> 
>   drivers/i2c/Kconfig      |   7 +
>   drivers/i2c/Makefile     |   1 +
>   drivers/i2c/mt7621_i2c.c | 374 +++++++++++++++++++++++++++++++++++++++
>   3 files changed, 382 insertions(+)
>   create mode 100644 drivers/i2c/mt7621_i2c.c

Thanks for fixing the checkpatch warnings.

Reviewed-by: Heiko Schocher <hs at nabladev.com>

bye,
Heiko
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