[PATCH v3] i2c: add support for the MT7621 I2C controller

[Heiko Schocher]

Hello Justin,

I am sorry, checkpatch drops some warnings, can you please fix them?

Thanks!

bye,
Heiko

[1] checkpatch warnings
WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
#233:
new file mode 100644

ERROR: Do not add common.h to files
#260: FILE: drivers/i2c/mt7621_i2c.c:23:
+#include <common.h>

CHECK: Prefer using the BIT macro
#281: FILE: drivers/i2c/mt7621_i2c.c:44:
+#define SM0CTL1_START                 (1 << 4)

ERROR: open brace '{' following struct go on the same line
#294: FILE: drivers/i2c/mt7621_i2c.c:57:
+struct mt7621_i2c_priv
+{

ERROR: trailing whitespace
#323: FILE: drivers/i2c/mt7621_i2c.c:86:
+^I$

ERROR: trailing whitespace
#327: FILE: drivers/i2c/mt7621_i2c.c:90:
+^I$

WARNING: Use of volatile is usually wrong: see Documentation/process/volatile-considered-harmful.rst
#409: FILE: drivers/i2c/mt7621_i2c.c:172:
+       u32 status = *(volatile u32 *)(priv->base + REG_SM0CTL1);

ERROR: trailing whitespace
#415: FILE: drivers/i2c/mt7621_i2c.c:178:
+^I$

ERROR: trailing whitespace
#464: FILE: drivers/i2c/mt7621_i2c.c:227:
+^I^I$

ERROR: trailing whitespace
#468: FILE: drivers/i2c/mt7621_i2c.c:231:
+^I^I$

ERROR: trailing whitespace
#481: FILE: drivers/i2c/mt7621_i2c.c:244:
+^I$

ERROR: trailing whitespace
#484: FILE: drivers/i2c/mt7621_i2c.c:247:
+^I^I$

ERROR: trailing whitespace
#488: FILE: drivers/i2c/mt7621_i2c.c:251:
+^I^I$

ERROR: trailing whitespace
#492: FILE: drivers/i2c/mt7621_i2c.c:255:
+^I^I$

ERROR: trailing whitespace
#496: FILE: drivers/i2c/mt7621_i2c.c:259:
+^I^I$

ERROR: trailing whitespace
#500: FILE: drivers/i2c/mt7621_i2c.c:263:
+^I^I$

ERROR: trailing whitespace
#511: FILE: drivers/i2c/mt7621_i2c.c:274:
+^I$

ERROR: trailing whitespace
#519: FILE: drivers/i2c/mt7621_i2c.c:282:
+^I$

ERROR: trailing whitespace
#521: FILE: drivers/i2c/mt7621_i2c.c:284:
+^I$

ERROR: trailing whitespace
#546: FILE: drivers/i2c/mt7621_i2c.c:309:
+^I$

total: 17 errors, 2 warnings, 1 checks, 395 lines checked

On 27.10.25 05:49, Heiko Schocher wrote:
> Hello Justin,
> 
> On 08.10.25 13:48, 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 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 | 375 +++++++++++++++++++++++++++++++++++++++
>>   3 files changed, 383 insertions(+)
>>   create mode 100644 drivers/i2c/mt7621_i2c.c
> 
> Reviewed-by: Heiko Schocher <hs at nabladev.com>
> 
> bye,
> Heiko

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