diff mbox series

[v2,1/2] dt-bindings: i2c: spacemit: add support for K1 SoC

Message ID 20241028053220.346283-2-TroyMitchell988@gmail.com
State New
Headers show
Series riscv: spacemit: add i2c support to K1 SoC | expand

Commit Message

Troy Mitchell Oct. 28, 2024, 5:32 a.m. UTC 
The I2C of K1 supports fast-speed-mode and high-speed-mode,
and supports FIFO transmission.

Signed-off-by: Troy Mitchell <TroyMitchell988@gmail.com>
---
 .../bindings/i2c/spacemit,k1-i2c.yaml         | 51 +++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml

Comments

Samuel Holland Nov. 2, 2024, 3:48 a.m. UTC | #1 
Hi Troy,

On 2024-10-28 12:32 AM, Troy Mitchell wrote:
> The I2C of K1 supports fast-speed-mode and high-speed-mode,
> and supports FIFO transmission.
> 
> Signed-off-by: Troy Mitchell <TroyMitchell988@gmail.com>
> ---
>  .../bindings/i2c/spacemit,k1-i2c.yaml         | 51 +++++++++++++++++++
>  1 file changed, 51 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
> 
> diff --git a/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml b/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
> new file mode 100644
> index 000000000000..57af66f494e7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
> @@ -0,0 +1,51 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/i2c/spacemit,k1-i2c.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: I2C controller embedded in SpacemiT's K1 SoC
> +
> +maintainers:
> +  - Troy Mitchell <troymitchell988@gmail.com>
> +
> +properties:
> +  compatible:
> +    const: spacemit,k1-i2c
> +
> +  reg:
> +    maxItems: 2
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  clocks:
> +    maxItems: 1

Looking at the K1 user manual (9.1.4.77 RCPU I2C0 CLOCK RESET CONTROL
REGISTER(RCPU_I2C0_CLK_RST)), I see two clocks (pclk, fclk) and a reset, which
looks to be standard across the peripherals in this SoC. Please be sure that the
binding covers all resources needed to use this peripheral.

> +
> +  clock-frequency:
> +    description:
> +      Desired I2C bus clock frequency in Hz. As only fast and high-speed
> +      modes are supported by hardware, possible values are 100000 and 400000.
> +    enum: [100000, 400000]

This looks wrong. In the manual I see:

* Supports standard-mode operation up to 100 Kbps
* Supports fast-mode operation up to 400Kbps
* Supports high-speed mode (HS mode) slave operation up to 3.4Mbps(High-speed
I2C only)
* Supports high-speed mode (HS mode) master operation up to 3.3 Mbps (High-speed
I2C only)

So even ignoring HS mode, 100 kHz and 400 kHz are only the maximums, not fixed
frequencies.

Regards,
Samuel

> +    default: 100000
> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +  - clocks
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    i2c@d4010800 {
> +        compatible = "spacemit,k1-i2c";
> +        reg = <0x0 0xd4010800 0x0 0x38>;
> +        interrupt-parent = <&plic>;
> +        interrupts = <36>;
> +        clocks = <&ccu 90>;
> +        clock-frequency = <100000>;
> +    };
> +
> +...
Troy Mitchell Nov. 6, 2024, 7:58 a.m. UTC | #2 
On 2024/11/2 11:48, Samuel Holland wrote:
> Hi Troy,
> 
> On 2024-10-28 12:32 AM, Troy Mitchell wrote:
>> The I2C of K1 supports fast-speed-mode and high-speed-mode,
>> and supports FIFO transmission.
>>
>> Signed-off-by: Troy Mitchell <TroyMitchell988@gmail.com>
>> ---
>>  .../bindings/i2c/spacemit,k1-i2c.yaml         | 51 +++++++++++++++++++
>>  1 file changed, 51 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml b/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
>> new file mode 100644
>> index 000000000000..57af66f494e7
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
>> @@ -0,0 +1,51 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/i2c/spacemit,k1-i2c.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: I2C controller embedded in SpacemiT's K1 SoC
>> +
>> +maintainers:
>> +  - Troy Mitchell <troymitchell988@gmail.com>
>> +
>> +properties:
>> +  compatible:
>> +    const: spacemit,k1-i2c
>> +
>> +  reg:
>> +    maxItems: 2
>> +
>> +  interrupts:
>> +    maxItems: 1
>> +
>> +  clocks:
>> +    maxItems: 1
> 
> Looking at the K1 user manual (9.1.4.77 RCPU I2C0 CLOCK RESET CONTROL
> REGISTER(RCPU_I2C0_CLK_RST)), I see two clocks (pclk, fclk) and a reset, which
> looks to be standard across the peripherals in this SoC. Please be sure that the
> binding covers all resources needed to use this peripheral.RCPU stands for Real-time CPU, which is typically used for low power consumption
applications.
We should be using the APBC_TWSIx_CLK_RST register, but it's not listed in the
user manual. However, you can find this register referenced in the K1 clock patch:
https://lore.kernel.org/all/SEYPR01MB4221AA2CA9C91A695FEFA777D7602@SEYPR01MB4221.apcprd01.prod.exchangelabs.com/

Also, to see how to enable the I2C clock in the device tree (note that the
spacemit,apb_clock property is unused in the driver), check out the example here:
https://gitee.com/bianbu-linux/linux-6.1/blob/bl-v1.0.y/arch/riscv/boot/dts/spacemit/k1-x.dtsi#L1048

> 
>> +
>> +  clock-frequency:
>> +    description:
>> +      Desired I2C bus clock frequency in Hz. As only fast and high-speed
>> +      modes are supported by hardware, possible values are 100000 and 400000.
>> +    enum: [100000, 400000]
> 
> This looks wrong. In the manual I see:
> 
> * Supports standard-mode operation up to 100 Kbps
> * Supports fast-mode operation up to 400Kbps
> * Supports high-speed mode (HS mode) slave operation up to 3.4Mbps(High-speed
> I2C only)
> * Supports high-speed mode (HS mode) master operation up to 3.3 Mbps (High-speed
> I2C only)
> 
> So even ignoring HS mode, 100 kHz and 400 kHz are only the maximums, not fixed
> frequencies.
okay. I will fix it in next version.
and should I keep to ignore high-speed mode here?
if not, how about this:

  clock-frequency:
    description:
      Desired I2C bus clock frequency in Hz.
      K1 supports standard, fast, high-speed modes, from 1 to 3300000.
    default: 100000
    minimum: 1
    maximum: 3300000

> 
> Regards,
> Samuel
> 
>> +    default: 100000
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - interrupts
>> +  - clocks
>> +
>> +unevaluatedProperties: false
>> +
>> +examples:
>> +  - |
>> +    i2c@d4010800 {
>> +        compatible = "spacemit,k1-i2c";
>> +        reg = <0x0 0xd4010800 0x0 0x38>;
>> +        interrupt-parent = <&plic>;
>> +        interrupts = <36>;
>> +        clocks = <&ccu 90>;
>> +        clock-frequency = <100000>;
>> +    };
>> +
>> +...
>
Samuel Holland Nov. 7, 2024, 12:29 a.m. UTC | #3 
Hi Troy,

On 2024-11-06 1:58 AM, Troy Mitchell wrote:
> On 2024/11/2 11:48, Samuel Holland wrote:
>> On 2024-10-28 12:32 AM, Troy Mitchell wrote:
>>> The I2C of K1 supports fast-speed-mode and high-speed-mode,
>>> and supports FIFO transmission.
>>>
>>> Signed-off-by: Troy Mitchell <TroyMitchell988@gmail.com>
>>> ---
>>>  .../bindings/i2c/spacemit,k1-i2c.yaml         | 51 +++++++++++++++++++
>>>  1 file changed, 51 insertions(+)
>>>  create mode 100644 Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml b/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
>>> new file mode 100644
>>> index 000000000000..57af66f494e7
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
>>> @@ -0,0 +1,51 @@
>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>> +%YAML 1.2
>>> +---
>>> +$id: http://devicetree.org/schemas/i2c/spacemit,k1-i2c.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> +
>>> +title: I2C controller embedded in SpacemiT's K1 SoC
>>> +
>>> +maintainers:
>>> +  - Troy Mitchell <troymitchell988@gmail.com>
>>> +
>>> +properties:
>>> +  compatible:
>>> +    const: spacemit,k1-i2c
>>> +
>>> +  reg:
>>> +    maxItems: 2
>>> +
>>> +  interrupts:
>>> +    maxItems: 1
>>> +
>>> +  clocks:
>>> +    maxItems: 1
>>
>> Looking at the K1 user manual (9.1.4.77 RCPU I2C0 CLOCK RESET CONTROL
>> REGISTER(RCPU_I2C0_CLK_RST)), I see two clocks (pclk, fclk) and a reset, which
>> looks to be standard across the peripherals in this SoC. Please be sure that the
>> binding covers all resources needed to use this peripheral.
>
> RCPU stands for Real-time CPU, which is typically used for low power consumption
> applications.
> We should be using the APBC_TWSIx_CLK_RST register, but it's not listed in the
> user manual. However, you can find this register referenced in the K1 clock patch:
> https://lore.kernel.org/all/SEYPR01MB4221AA2CA9C91A695FEFA777D7602@SEYPR01MB4221.apcprd01.prod.exchangelabs.com/

Ah, well that driver is missing most of the bus clocks. For example, from a
quick comparison with the manual, the driver includes sdh_axi_aclk, but misses
all of the PWM APB clocks at APBC_PWMx_CLK_RST bit 0.

If the clock gate exists in the hardware, even if it is enabled by default, it
needs to be modeled in the devicetree.

> Also, to see how to enable the I2C clock in the device tree (note that the
> spacemit,apb_clock property is unused in the driver), check out the example here:
> https://gitee.com/bianbu-linux/linux-6.1/blob/bl-v1.0.y/arch/riscv/boot/dts/spacemit/k1-x.dtsi#L1048

The devicetree describes the hardware, irrespective of which features the driver
may or may not use.

>>> +
>>> +  clock-frequency:
>>> +    description:
>>> +      Desired I2C bus clock frequency in Hz. As only fast and high-speed
>>> +      modes are supported by hardware, possible values are 100000 and 400000.
>>> +    enum: [100000, 400000]
>>
>> This looks wrong. In the manual I see:
>>
>> * Supports standard-mode operation up to 100 Kbps
>> * Supports fast-mode operation up to 400Kbps
>> * Supports high-speed mode (HS mode) slave operation up to 3.4Mbps(High-speed
>> I2C only)
>> * Supports high-speed mode (HS mode) master operation up to 3.3 Mbps (High-speed
>> I2C only)
>>
>> So even ignoring HS mode, 100 kHz and 400 kHz are only the maximums, not fixed
>> frequencies.
> okay. I will fix it in next version.
> and should I keep to ignore high-speed mode here?
> if not, how about this:
> 
>   clock-frequency:
>     description:
>       Desired I2C bus clock frequency in Hz.
>       K1 supports standard, fast, high-speed modes, from 1 to 3300000.
>     default: 100000
>     minimum: 1
>     maximum: 3300000

I don't know if high-speed mode should be included, since it requires some extra
negotiation to use. Assuming it should be, that looks reasonable.

Regards,
Samuel

>>
>> Regards,
>> Samuel
>>
>>> +    default: 100000
>>> +
>>> +required:
>>> +  - compatible
>>> +  - reg
>>> +  - interrupts
>>> +  - clocks
>>> +
>>> +unevaluatedProperties: false
>>> +
>>> +examples:
>>> +  - |
>>> +    i2c@d4010800 {
>>> +        compatible = "spacemit,k1-i2c";
>>> +        reg = <0x0 0xd4010800 0x0 0x38>;
>>> +        interrupt-parent = <&plic>;
>>> +        interrupts = <36>;
>>> +        clocks = <&ccu 90>;
>>> +        clock-frequency = <100000>;
>>> +    };
>>> +
>>> +...
>>
>
Troy Mitchell Nov. 7, 2024, 1:57 a.m. UTC | #4 
On 2024/11/7 08:29, Samuel Holland wrote:
> Hi Troy,
> 
> On 2024-11-06 1:58 AM, Troy Mitchell wrote:
>> On 2024/11/2 11:48, Samuel Holland wrote:
>>> On 2024-10-28 12:32 AM, Troy Mitchell wrote:
>>>> The I2C of K1 supports fast-speed-mode and high-speed-mode,
>>>> and supports FIFO transmission.
>>>>
>>>> Signed-off-by: Troy Mitchell <TroyMitchell988@gmail.com>
>>>> ---
>>>>  .../bindings/i2c/spacemit,k1-i2c.yaml         | 51 +++++++++++++++++++
>>>>  1 file changed, 51 insertions(+)
>>>>  create mode 100644 Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml b/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
>>>> new file mode 100644
>>>> index 000000000000..57af66f494e7
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
>>>> @@ -0,0 +1,51 @@
>>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>>> +%YAML 1.2
>>>> +---
>>>> +$id: http://devicetree.org/schemas/i2c/spacemit,k1-i2c.yaml#
>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>> +
>>>> +title: I2C controller embedded in SpacemiT's K1 SoC
>>>> +
>>>> +maintainers:
>>>> +  - Troy Mitchell <troymitchell988@gmail.com>
>>>> +
>>>> +properties:
>>>> +  compatible:
>>>> +    const: spacemit,k1-i2c
>>>> +
>>>> +  reg:
>>>> +    maxItems: 2
>>>> +
>>>> +  interrupts:
>>>> +    maxItems: 1
>>>> +
>>>> +  clocks:
>>>> +    maxItems: 1
>>>
>>> Looking at the K1 user manual (9.1.4.77 RCPU I2C0 CLOCK RESET CONTROL
>>> REGISTER(RCPU_I2C0_CLK_RST)), I see two clocks (pclk, fclk) and a reset, which
>>> looks to be standard across the peripherals in this SoC. Please be sure that the
>>> binding covers all resources needed to use this peripheral.
>>
>> RCPU stands for Real-time CPU, which is typically used for low power consumption
>> applications.
>> We should be using the APBC_TWSIx_CLK_RST register, but it's not listed in the
>> user manual. However, you can find this register referenced in the K1 clock patch:
>> https://lore.kernel.org/all/SEYPR01MB4221AA2CA9C91A695FEFA777D7602@SEYPR01MB4221.apcprd01.prod.exchangelabs.com/
> 
> Ah, well that driver is missing most of the bus clocks. For example, from a
> quick comparison with the manual, the driver includes sdh_axi_aclk, but misses
> all of the PWM APB clocks at APBC_PWMx_CLK_RST bit 0.
> 
> If the clock gate exists in the hardware, even if it is enabled by default, it
> needs to be modeled in the devicetree.
I think you mean `APBCSCR`? It will keep enable all time.Just a difference in
frequency.

Should I add it in clockc property? If yes, how about this:
    clocks:
        maxItems: 1

and in dts example:
    i2c@d4010800 {
	...
        clocks = <&clk_apbc>, <&ccu 90>;
	clock-names = "clk_apbc", "clk_twsi";
        ...
    };
But one thing is, apbc_twsi is the sub-clock of clk_apbc, is this a duplicate
listing?
> 
>> Also, to see how to enable the I2C clock in the device tree (note that the
>> spacemit,apb_clock property is unused in the driver), check out the example here:
>> https://gitee.com/bianbu-linux/linux-6.1/blob/bl-v1.0.y/arch/riscv/boot/dts/spacemit/k1-x.dtsi#L1048
> 
> The devicetree describes the hardware, irrespective of which features the driver
> may or may not use.
> 
>>>> +
>>>> +  clock-frequency:
>>>> +    description:
>>>> +      Desired I2C bus clock frequency in Hz. As only fast and high-speed
>>>> +      modes are supported by hardware, possible values are 100000 and 400000.
>>>> +    enum: [100000, 400000]
>>>
>>> This looks wrong. In the manual I see:
>>>
>>> * Supports standard-mode operation up to 100 Kbps
>>> * Supports fast-mode operation up to 400Kbps
>>> * Supports high-speed mode (HS mode) slave operation up to 3.4Mbps(High-speed
>>> I2C only)
>>> * Supports high-speed mode (HS mode) master operation up to 3.3 Mbps (High-speed
>>> I2C only)
>>>
>>> So even ignoring HS mode, 100 kHz and 400 kHz are only the maximums, not fixed
>>> frequencies.
>> okay. I will fix it in next version.
>> and should I keep to ignore high-speed mode here?
>> if not, how about this:
>>
>>   clock-frequency:
>>     description:
>>       Desired I2C bus clock frequency in Hz.
>>       K1 supports standard, fast, high-speed modes, from 1 to 3300000.
>>     default: 100000
>>     minimum: 1
>>     maximum: 3300000
> 
> I don't know if high-speed mode should be included, since it requires some extra
> negotiation to use. Assuming it should be, that looks reasonable.
thanks.
> 
> Regards,
> Samuel
> 
>>>
>>> Regards,
>>> Samuel
>>>
>>>> +    default: 100000
>>>> +
>>>> +required:
>>>> +  - compatible
>>>> +  - reg
>>>> +  - interrupts
>>>> +  - clocks
>>>> +
>>>> +unevaluatedProperties: false
>>>> +
>>>> +examples:
>>>> +  - |
>>>> +    i2c@d4010800 {
>>>> +        compatible = "spacemit,k1-i2c";
>>>> +        reg = <0x0 0xd4010800 0x0 0x38>;
>>>> +        interrupt-parent = <&plic>;
>>>> +        interrupts = <36>;
>>>> +        clocks = <&ccu 90>;
>>>> +        clock-frequency = <100000>;
>>>> +    };
>>>> +
>>>> +...
>>>
>>
>
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml b/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
new file mode 100644
index 000000000000..57af66f494e7
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml
@@ -0,0 +1,51 @@ 
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/i2c/spacemit,k1-i2c.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: I2C controller embedded in SpacemiT's K1 SoC
+
+maintainers:
+  - Troy Mitchell <troymitchell988@gmail.com>
+
+properties:
+  compatible:
+    const: spacemit,k1-i2c
+
+  reg:
+    maxItems: 2
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-frequency:
+    description:
+      Desired I2C bus clock frequency in Hz. As only fast and high-speed
+      modes are supported by hardware, possible values are 100000 and 400000.
+    enum: [100000, 400000]
+    default: 100000
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    i2c@d4010800 {
+        compatible = "spacemit,k1-i2c";
+        reg = <0x0 0xd4010800 0x0 0x38>;
+        interrupt-parent = <&plic>;
+        interrupts = <36>;
+        clocks = <&ccu 90>;
+        clock-frequency = <100000>;
+    };
+
+...