[PATCH v3 0/3] i2c: spacemit: add reset support

[PATCH v3 0/3] i2c: spacemit: add reset support

[Encrow Thorne]

Add reset support for the K1 I2C driver. A reset ensures that the
controller starts in a clean and known state.

Reset ensures that the I2C hardware is in a clean state. We cannot assume
that no program used I2C before the kernel booted.

Signed-off-by: Encrow Thorne <jyc0019@gmail.com>
---
Changes in v3:
- Move reset property in dt-bindings.
- Use devm_reset_control_get_optional_exclusive_deasserted() instead.
- Rebase to v6.19-rc1.
- Link to v2: https://lore.kernel.org/r/20251219-i2c-reset-v2-0-ad201a602e74@gmail.com

Changes in v2:
- Replace reset property in dt-bindings.
- Use devm_reset_control_get_optional_exclusive_deasserted() instead.
- Rebase to v6.19-rc1.
- Link to v1: https://lore.kernel.org/r/20251119-i2c-k1_reset-support-v1-0-0e9e82bf9b65@gmail.com

---
Encrow Thorne (3):
      dt-bindings: i2c: spacemit: add optional resets
      i2c: k1: add reset support
      riscv: dts: spacemit: add reset property

 Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml | 3 +++
 arch/riscv/boot/dts/spacemit/k1.dtsi                       | 8 ++++++++
 drivers/i2c/busses/i2c-k1.c                                | 7 +++++++
 3 files changed, 18 insertions(+)
---
base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
change-id: 20251218-i2c-reset-a7be139213de

Best regards,
-- 
Encrow Thorne <jyc0019@gmail.com>

[PATCH 1/3] dt-bindings: i2c: spacemit: add optional resets

[Encrow Thorne]

The I2C controller requires a reset to ensure it starts from a clean state.

Add the 'resets' property to support this hardware requirement.

Reviewed-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
Signed-off-by: Encrow Thorne <jyc0019@gmail.com>
---
 Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml b/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
index b7220fff2235..5896fb120501 100644
--- a/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
+++ b/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
@@ -41,6 +41,9 @@ properties:
     default: 400000
     maximum: 3300000
 
+  resets:
+    maxItems: 1
+
 required:
   - compatible
   - reg
-- 
2.25.1

[PATCH 2/3] i2c: k1: add reset support

[Encrow Thorne]

The K1 I2C controller provides a reset line that needs to be deasserted
before the controller can be accessed.

Add reset support to the driver to ensure the controller starts in the
required state.

Reviewed-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
Signed-off-by: Encrow Thorne <jyc0019@gmail.com>
---
 drivers/i2c/busses/i2c-k1.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/i2c/busses/i2c-k1.c b/drivers/i2c/busses/i2c-k1.c
index d42c03ef5db5..23661c7ddb67 100644
--- a/drivers/i2c/busses/i2c-k1.c
+++ b/drivers/i2c/busses/i2c-k1.c
@@ -10,6 +10,7 @@
  #include <linux/module.h>
  #include <linux/of_address.h>
  #include <linux/platform_device.h>
+ #include <linux/reset.h>
 
 /* spacemit i2c registers */
 #define SPACEMIT_ICR		 0x0		/* Control register */
@@ -534,6 +535,7 @@ static int spacemit_i2c_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct device_node *of_node = pdev->dev.of_node;
 	struct spacemit_i2c_dev *i2c;
+	struct reset_control *rst;
 	int ret;
 
 	i2c = devm_kzalloc(dev, sizeof(*i2c), GFP_KERNEL);
@@ -578,6 +580,11 @@ static int spacemit_i2c_probe(struct platform_device *pdev)
 	if (IS_ERR(clk))
 		return dev_err_probe(dev, PTR_ERR(clk), "failed to enable bus clock");
 
+	rst = devm_reset_control_get_optional_exclusive_deasserted(dev, NULL);
+	if (IS_ERR(rst))
+		return dev_err_probe(dev, PTR_ERR(rst),
+				     "failed to acquire deasserted reset\n");
+
 	spacemit_i2c_reset(i2c);
 
 	i2c_set_adapdata(&i2c->adapt, i2c);
-- 
2.25.1

[PATCH 3/3] riscv: dts: spacemit: add reset property

[Encrow Thorne]

Add resets property to K1 I2C node.
---
 arch/riscv/boot/dts/spacemit/k1.dtsi | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/riscv/boot/dts/spacemit/k1.dtsi b/arch/riscv/boot/dts/spacemit/k1.dtsi
index 7818ca4979b6..085987643638 100644
--- a/arch/riscv/boot/dts/spacemit/k1.dtsi
+++ b/arch/riscv/boot/dts/spacemit/k1.dtsi
@@ -367,6 +367,7 @@ i2c0: i2c@d4010800 {
 				 <&syscon_apbc CLK_TWSI0_BUS>;
 			clock-names = "func", "bus";
 			clock-frequency = <400000>;
+			resets = <&syscon_apbc RESET_TWSI0>;
 			interrupts = <36>;
 			status = "disabled";
 		};
@@ -380,6 +381,7 @@ i2c1: i2c@d4011000 {
 				 <&syscon_apbc CLK_TWSI1_BUS>;
 			clock-names = "func", "bus";
 			clock-frequency = <400000>;
+			resets = <&syscon_apbc RESET_TWSI1>;
 			interrupts = <37>;
 			status = "disabled";
 		};
@@ -393,6 +395,7 @@ i2c2: i2c@d4012000 {
 				 <&syscon_apbc CLK_TWSI2_BUS>;
 			clock-names = "func", "bus";
 			clock-frequency = <400000>;
+			resets = <&syscon_apbc RESET_TWSI2>;
 			interrupts = <38>;
 			status = "disabled";
 		};
@@ -406,6 +409,7 @@ i2c4: i2c@d4012800 {
 				 <&syscon_apbc CLK_TWSI4_BUS>;
 			clock-names = "func", "bus";
 			clock-frequency = <400000>;
+			resets = <&syscon_apbc RESET_TWSI4>;
 			interrupts = <40>;
 			status = "disabled";
 		};
@@ -419,6 +423,7 @@ i2c5: i2c@d4013800 {
 				 <&syscon_apbc CLK_TWSI5_BUS>;
 			clock-names = "func", "bus";
 			clock-frequency = <400000>;
+			resets = <&syscon_apbc RESET_TWSI5>;
 			interrupts = <41>;
 			status = "disabled";
 		};
@@ -443,6 +448,7 @@ i2c6: i2c@d4018800 {
 				 <&syscon_apbc CLK_TWSI6_BUS>;
 			clock-names = "func", "bus";
 			clock-frequency = <400000>;
+			resets = <&syscon_apbc RESET_TWSI6>;
 			interrupts = <70>;
 			status = "disabled";
 		};
@@ -546,6 +552,7 @@ i2c7: i2c@d401d000 {
 				 <&syscon_apbc CLK_TWSI7_BUS>;
 			clock-names = "func", "bus";
 			clock-frequency = <400000>;
+			resets = <&syscon_apbc RESET_TWSI7>;
 			interrupts = <18>;
 			status = "disabled";
 		};
@@ -559,6 +566,7 @@ i2c8: i2c@d401d800 {
 				 <&syscon_apbc CLK_TWSI8_BUS>;
 			clock-names = "func", "bus";
 			clock-frequency = <400000>;
+			resets = <&syscon_apbc RESET_TWSI8>;
 			interrupts = <19>;
 			status = "disabled";
 		};
-- 
2.25.1

Re: [PATCH 3/3] riscv: dts: spacemit: add reset property

[Andi Shyti]

Hi Encrow,

On Tue, Dec 30, 2025 at 11:06:53PM +0800, Encrow Thorne wrote:
> Add resets property to K1 I2C node.
> ---
>  arch/riscv/boot/dts/spacemit/k1.dtsi | 8 ++++++++
>  1 file changed, 8 insertions(+)

how is this patch formatted?

Andi

Re: [PATCH 3/3] riscv: dts: spacemit: add reset property

[Encrow Thorne]

On Wed, Jan 07, 2026 at 03:22:42PM +0100, Andi Shyti wrote:
  Hi Andi,
> Hi Encrow,
> 
> On Tue, Dec 30, 2025 at 11:06:53PM +0800, Encrow Thorne wrote:
> > Add resets property to K1 I2C node.
> > ---
> >  arch/riscv/boot/dts/spacemit/k1.dtsi | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> 
> how is this patch formatted?
> 
  Sorry, I forgot to add the version number when I resent it.

  The initial sending process was interrupted, so I
  manually regenerated the patches using git format-patch 
  and sent them again.I have verified locally that the 
  entire patch series applies cleanly.

  Please let me know if you find any other formatting issues.

  Encrow
> Andi

Re: [PATCH 3/3] riscv: dts: spacemit: add reset property

[Andi Shyti]

Hi Encrow,

On Thu, Jan 08, 2026 at 12:23:43AM +0800, Encrow Thorne wrote:
> On Wed, Jan 07, 2026 at 03:22:42PM +0100, Andi Shyti wrote:
>   Hi Andi,
> > Hi Encrow,
> > 
> > On Tue, Dec 30, 2025 at 11:06:53PM +0800, Encrow Thorne wrote:
> > > Add resets property to K1 I2C node.
> > > ---
> > >  arch/riscv/boot/dts/spacemit/k1.dtsi | 8 ++++++++
> > >  1 file changed, 8 insertions(+)
> > 
> > how is this patch formatted?
> > 
>   Sorry, I forgot to add the version number when I resent it.

you also forgot the tag section :-)

No worries, I took patch 1 and 2 into i2c/i2c-host branch.

Thanks,
Andi

Re: [PATCH 1/3] dt-bindings: i2c: spacemit: add optional resets

[Rob Herring (Arm)]

On Tue, 30 Dec 2025 23:06:51 +0800, Encrow Thorne wrote:
> The I2C controller requires a reset to ensure it starts from a clean state.
> 
> Add the 'resets' property to support this hardware requirement.
> 
> Reviewed-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
> Signed-off-by: Encrow Thorne <jyc0019@gmail.com>
> ---
>  Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml | 3 +++
>  1 file changed, 3 insertions(+)
> 

Acked-by: Rob Herring (Arm) <robh@kernel.org>

Re: (subset) [PATCH v3 0/3] i2c: spacemit: add reset support

[Yixun Lan]

On Tue, 30 Dec 2025 22:29:01 +0800, Encrow Thorne wrote:
> Add reset support for the K1 I2C driver. A reset ensures that the
> controller starts in a clean and known state.
> 
> Reset ensures that the I2C hardware is in a clean state. We cannot assume
> that no program used I2C before the kernel booted.
> 
> 
> [...]

Applied, thanks!

[3/3] riscv: dts: spacemit: add reset property
      https://github.com/spacemit-com/linux/commit/91c444d4285c07dbf2e6e4bf954d9a0282157f1f

Best regards,
-- 
Yixun Lan

[PATCH 0/3] i2c: spacemit: add reset support

[Encrow Thorne]

Add reset control to SpacemiT K1 I2C.

Signed-off-by: Encrow Thorne <jyc0019@gmail.com>
---
Encrow Thorne (3):
      dt-bindings: i2c: spacemit: add optional resets
      i2c: k1: add reset support
      riscv: dts: spacemit: add reset property

 Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml |  3 +++
 arch/riscv/boot/dts/spacemit/k1.dtsi                       |  2 ++
 drivers/i2c/busses/i2c-k1.c                                | 11 +++++++++++
 3 files changed, 16 insertions(+)
---
base-commit: 8fec172c82c2b5f6f8e47ab837c1dc91ee3d1b87
change-id: 20251104-i2c-k1_reset-support-12784e17bf83

Best regards,
-- 
Encrow Thorne <jyc0019@gmail.com>

[PATCH 1/3] dt-bindings: i2c: spacemit: add optional resets

[Encrow Thorne]

Add optional reset property for the SpacemiT K1 I2C.

Signed-off-by: Encrow Thorne <jyc0019@gmail.com>
---
 Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml b/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
index b7220fff2235..3d4faec41abe 100644
--- a/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
+++ b/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
@@ -27,6 +27,9 @@ properties:
       - description: I2C Functional Clock
       - description: APB Bus Clock
 
+  resets:
+    maxItems: 1
+
   clock-names:
     items:
       - const: func

-- 
2.25.1

Re: [PATCH 1/3] dt-bindings: i2c: spacemit: add optional resets

[Troy Mitchell]

On Wed, Nov 19, 2025 at 07:46:43PM +0800, Encrow Thorne wrote:
> Add optional reset property for the SpacemiT K1 I2C.
> 
> Signed-off-by: Encrow Thorne <jyc0019@gmail.com>
>
Thanks.

Acked-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>

Re: [PATCH 1/3] dt-bindings: i2c: spacemit: add optional resets

[Krzysztof Kozlowski]

On Wed, Nov 19, 2025 at 07:46:43PM +0800, Encrow Thorne wrote:
> Add optional reset property for the SpacemiT K1 I2C.

Why? You just repeated diff and we can read the diff. Please explain WHY
you are doing things in terms of hardware.

> 
> Signed-off-by: Encrow Thorne <jyc0019@gmail.com>
> ---
>  Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml b/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
> index b7220fff2235..3d4faec41abe 100644
> --- a/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
> +++ b/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
> @@ -27,6 +27,9 @@ properties:
>        - description: I2C Functional Clock
>        - description: APB Bus Clock
>  
> +  resets:
> +    maxItems: 1
> +

Completely misplaced. There are never random properties between xxx and
xxx-names.

Best regards,
Krzysztof