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Re: [PATCH v4 3/5] i2c: designware: Add slave definitions

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  Re: [PATCH v4 3/5] i2c: designware: Add slave definitions Rob Herring <robh@kernel.org> - 2016-12-12 18:10 +0100
    RE: [PATCH v4 3/5] i2c: designware: Add slave definitions Luis de Oliveira <Luis.Oliveira@synopsys.com> - 2016-12-12 19:40 +0100
      Re: [PATCH v4 3/5] i2c: designware: Add slave definitions Rob Herring <robh@kernel.org> - 2016-12-13 00:20 +0100
        RE: [PATCH v4 3/5] i2c: designware: Add slave definitions Luis de Oliveira <Luis.Oliveira@synopsys.com> - 2016-12-13 12:10 +0100
          Re: [PATCH v4 3/5] i2c: designware: Add slave definitions Rob Herring <robh@kernel.org> - 2016-12-13 15:20 +0100
            Re: [PATCH v4 3/5] i2c: designware: Add slave definitions Luis Oliveira <Luis.Oliveira@synopsys.com> - 2016-12-22 16:10 +0100
              Re: [PATCH v4 3/5] i2c: designware: Add slave definitions Andy Shevchenko <andriy.shevchenko@linux.intel.com> - 2016-12-22 16:40 +0100

#1540461 — Re: [PATCH v4 3/5] i2c: designware: Add slave definitions

On Wed, Dec 07, 2016 at 05:55:50PM +0000, Luis Oliveira wrote:
> - Add slave definitions to i2c-designware-core
> - Changes in Kconfig to auto-enable I2C_SLAVE when compiling the modules
> - Add mode property to designware-core.txt that enable the "slave" selection:
>   - "mode" is an optional property that could be "slave" or "master"
>   - if "mode" is not set the block is considered master by default
> 
> Signed-off-by: Luis Oliveira <lolivei@synopsys.com>
> ---
> Changes V3->V4: (Andy Shevchenko)
> - created a common property for modes 
> - placed the generic dependency first
> 
>  .../devicetree/bindings/i2c/i2c-designware.txt     |  4 ++++
>  drivers/i2c/busses/Kconfig                         |  1 +
>  drivers/i2c/busses/i2c-designware-common.c         |  6 +++++
>  drivers/i2c/busses/i2c-designware-core.h           | 26 ++++++++++++++++++++++
>  4 files changed, 37 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> index fee26dc3e858..8ed2b532cd54 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> @@ -20,6 +20,9 @@ Optional properties :
>   - i2c-sda-falling-time-ns : should contain the SDA falling time in nanoseconds.
>     This value which is by default 300ns is used to compute the tHIGH period.
>  
> + - mode : should be either:
> +           - "master" to setup the hardware block as a I2C master
> +           - "slave" to setup the hardware block as a I2C slave

This should be documented in a common location. Can't it be a boolean to 
enable slave mode? Or don't you need to set the slave address? That 
could be enough to enable slave mode and there's already one example 
doing that.

Rob

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#1540525

Hi all,

The slave address could be set by the I2C slave backend so I can't use it to setup the controller. 
A boolean property was my initial approach then Andy and Wolfram Sang suggested the use of compatible strings and later It was suggested to use a property to select mode but I can do it again if it's the best way. 
Can you please tell me where should it be documented? 

Luis

-----Original Message-----
From: Rob Herring [mailto:robh@kernel.org] 
Sent: Monday, December 12, 2016 17:02
To: Luis Oliveira <Luis.Oliveira@synopsys.com>
Cc: wsa@the-dreams.de; mark.rutland@arm.com; jarkko.nikula@linux.intel.com; andriy.shevchenko@linux.intel.com; mika.westerberg@linux.intel.com; linux-i2c@vger.kernel.org; devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; Ramiro.Oliveira@synopsys.com; Joao.Pinto@synopsys.com; CARLOS.PALMINHA@synopsys.com
Subject: Re: [PATCH v4 3/5] i2c: designware: Add slave definitions

On Wed, Dec 07, 2016 at 05:55:50PM +0000, Luis Oliveira wrote:
> - Add slave definitions to i2c-designware-core
> - Changes in Kconfig to auto-enable I2C_SLAVE when compiling the 
> modules
> - Add mode property to designware-core.txt that enable the "slave" selection:
>   - "mode" is an optional property that could be "slave" or "master"
>   - if "mode" is not set the block is considered master by default
> 
> Signed-off-by: Luis Oliveira <lolivei@synopsys.com>
> ---
> Changes V3->V4: (Andy Shevchenko)
> - created a common property for modes
> - placed the generic dependency first
> 
>  .../devicetree/bindings/i2c/i2c-designware.txt     |  4 ++++
>  drivers/i2c/busses/Kconfig                         |  1 +
>  drivers/i2c/busses/i2c-designware-common.c         |  6 +++++
>  drivers/i2c/busses/i2c-designware-core.h           | 26 ++++++++++++++++++++++
>  4 files changed, 37 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt 
> b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> index fee26dc3e858..8ed2b532cd54 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> @@ -20,6 +20,9 @@ Optional properties :
>   - i2c-sda-falling-time-ns : should contain the SDA falling time in nanoseconds.
>     This value which is by default 300ns is used to compute the tHIGH period.
>  
> + - mode : should be either:
> +           - "master" to setup the hardware block as a I2C master
> +           - "slave" to setup the hardware block as a I2C slave

This should be documented in a common location. Can't it be a boolean to enable slave mode? Or don't you need to set the slave address? That could be enough to enable slave mode and there's already one example doing that.

Rob

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#1540732

On Mon, Dec 12, 2016 at 12:35 PM, Luis de Oliveira
<Luis.Oliveira@synopsys.com> wrote:
> Hi all,

Please don't top post.

>
> The slave address could be set by the I2C slave backend so I can't use it to setup the controller.
> A boolean property was my initial approach then Andy and Wolfram Sang suggested the use of compatible strings and later It was suggested to use a property to select mode but I can do it again if it's the best way.
> Can you please tell me where should it be documented?

bindings/i2c/i2c.txt.

Actually, looking at this some more, we already have a way to describe
the controller being a slave device with the I2C_OWN_SLAVE_ADDRESS
flag in the reg property. We should just need a helper to read reg
property of each child and check for the bit set.

Rob

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#1540995

The controller for i2c-designware cannot be slave/master at the same time and it has to be enabled knowing beforehand if we want it to be slave or master by something outside of the controller itself.

I as looking and I see the use of this I2C_OWN_SLAVE_ADDRESS with the "linux,slave-24c02" slave interface  but I am not seeing how it will help me identify a selected i2c-designware block as a "slave" device before instantiation. I'm sorry if I'm not understanding properly.
I use the "linux,slave-24c02" to instantiate the i2c-designware as a slave with an address so I can do write/read operations, it is how I tested it. 

Luis

-----Original Message-----
From: Rob Herring [mailto:robh@kernel.org] 
Sent: Monday, December 12, 2016 23:16
To: Luis de Oliveira <Luis.Oliveira@synopsys.com>
Cc: wsa@the-dreams.de; mark.rutland@arm.com; jarkko.nikula@linux.intel.com; andriy.shevchenko@linux.intel.com; mika.westerberg@linux.intel.com; linux-i2c@vger.kernel.org; devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; Ramiro.Oliveira@synopsys.com; Joao.Pinto@synopsys.com; CARLOS.PALMINHA@synopsys.com
Subject: Re: [PATCH v4 3/5] i2c: designware: Add slave definitions

On Mon, Dec 12, 2016 at 12:35 PM, Luis de Oliveira <Luis.Oliveira@synopsys.com> wrote:
> Hi all,

Please don't top post.

>
> The slave address could be set by the I2C slave backend so I can't use it to setup the controller.
> A boolean property was my initial approach then Andy and Wolfram Sang suggested the use of compatible strings and later It was suggested to use a property to select mode but I can do it again if it's the best way.
> Can you please tell me where should it be documented?

bindings/i2c/i2c.txt.

Actually, looking at this some more, we already have a way to describe the controller being a slave device with the I2C_OWN_SLAVE_ADDRESS flag in the reg property. We should just need a helper to read reg property of each child and check for the bit set.

Rob

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#1541098

Again, please don't top post. And your line wrapping is messed up.
IOW, you can't use Outlook.

On Tue, Dec 13, 2016 at 4:50 AM, Luis de Oliveira
<Luis.Oliveira@synopsys.com> wrote:
> The controller for i2c-designware cannot be slave/master at the same time and it has to be enabled knowing beforehand if we want it to be slave or master by something outside of the controller itself.
>
> I as looking and I see the use of this I2C_OWN_SLAVE_ADDRESS with the "linux,slave-24c02" slave interface  but I am not seeing how it will help me identify a selected i2c-designware block as a "slave" device before instantiation. I'm sorry if I'm not understanding properly.
> I use the "linux,slave-24c02" to instantiate the i2c-designware as a slave with an address so I can do write/read operations, it is how I tested it.

Something like this:

of_for_each_child_node(child) {
  of_property_read_u32(child, "reg", &reg);
  if (reg & I2C_OWN_SLAVE_ADDRESS))
    im_a_slave = true;
}

...rather than testing "mode" is equal to "slave".

Rob

>
> Luis
>
> -----Original Message-----
> From: Rob Herring [mailto:robh@kernel.org]
> Sent: Monday, December 12, 2016 23:16
> To: Luis de Oliveira <Luis.Oliveira@synopsys.com>
> Cc: wsa@the-dreams.de; mark.rutland@arm.com; jarkko.nikula@linux.intel.com; andriy.shevchenko@linux.intel.com; mika.westerberg@linux.intel.com; linux-i2c@vger.kernel.org; devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; Ramiro.Oliveira@synopsys.com; Joao.Pinto@synopsys.com; CARLOS.PALMINHA@synopsys.com
> Subject: Re: [PATCH v4 3/5] i2c: designware: Add slave definitions
>
> On Mon, Dec 12, 2016 at 12:35 PM, Luis de Oliveira <Luis.Oliveira@synopsys.com> wrote:
>> Hi all,
>
> Please don't top post.
>
>>
>> The slave address could be set by the I2C slave backend so I can't use it to setup the controller.
>> A boolean property was my initial approach then Andy and Wolfram Sang suggested the use of compatible strings and later It was suggested to use a property to select mode but I can do it again if it's the best way.
>> Can you please tell me where should it be documented?
>
> bindings/i2c/i2c.txt.
>
> Actually, looking at this some more, we already have a way to describe the controller being a slave device with the I2C_OWN_SLAVE_ADDRESS flag in the reg property. We should just need a helper to read reg property of each child and check for the bit set.
>
> Rob

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#1546409

On 13-Dec-16 14:11, Rob Herring wrote:
> Again, please don't top post. And your line wrapping is messed up.
> IOW, you can't use Outlook.
> 
> On Tue, Dec 13, 2016 at 4:50 AM, Luis de Oliveira
> <Luis.Oliveira@synopsys.com> wrote:
>> The controller for i2c-designware cannot be slave/master at the same time and it has to be enabled knowing beforehand if we want it to be slave or master by something outside of the controller itself.
>>
>> I as looking and I see the use of this I2C_OWN_SLAVE_ADDRESS with the "linux,slave-24c02" slave interface  but I am not seeing how it will help me identify a selected i2c-designware block as a "slave" device before instantiation. I'm sorry if I'm not understanding properly.
>> I use the "linux,slave-24c02" to instantiate the i2c-designware as a slave with an address so I can do write/read operations, it is how I tested it.
> 
> Something like this:
> 
> of_for_each_child_node(child) {
>   of_property_read_u32(child, "reg", &reg);
>   if (reg & I2C_OWN_SLAVE_ADDRESS))
>     im_a_slave = true;
> }
> 
> ...rather than testing "mode" is equal to "slave".
> 
> Rob
> 

Hi Rob, Andy,

I'm struggling to implement your suggestion @Rob. I checked the
tegra124-jetson-tk1.dts that uses that approach but I have some doubts.

My DT is as follows

	i2c@0x2000 {
                        compatible = "snps,designware-i2c";
                        reg = <0x2000 0x100>;
                        clock-frequency = <400000>;
                        clocks = <&i2cclk>;
                        interrupts = <0>;

I could add something like this:

			eeprom@64 {
				compatible = "linux,slave-24c02";
				reg = <(I2C_OWN_SLAVE_ADDRESS | 0x64)>;
			}

But I think this is different form what I was doing before. I have two questions:

- This way the I2C controller is identified as a slave controller or just the
subnode eeprom?
- This way looks like my slave address will be fixed

In the previous Patch v3 submission @Andy suggested a property that selects mode
that I did and it's working. And you @Rob suggested to do it a common property.
It is implemented in the DT like:

			mode = "slave";

So before I do this changes can you please agree both if you still think this is
the best approach?


Thank you both for your time,
Luis

>>
>> Luis
>>
>> -----Original Message-----
>> From: Rob Herring [mailto:robh@kernel.org]
>> Sent: Monday, December 12, 2016 23:16
>> To: Luis de Oliveira <Luis.Oliveira@synopsys.com>
>> Cc: wsa@the-dreams.de; mark.rutland@arm.com; jarkko.nikula@linux.intel.com; andriy.shevchenko@linux.intel.com; mika.westerberg@linux.intel.com; linux-i2c@vger.kernel.org; devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; Ramiro.Oliveira@synopsys.com; Joao.Pinto@synopsys.com; CARLOS.PALMINHA@synopsys.com
>> Subject: Re: [PATCH v4 3/5] i2c: designware: Add slave definitions
>>
>> On Mon, Dec 12, 2016 at 12:35 PM, Luis de Oliveira <Luis.Oliveira@synopsys.com> wrote:
>>> Hi all,
>>
>> Please don't top post.
>>
>>>
>>> The slave address could be set by the I2C slave backend so I can't use it to setup the controller.
>>> A boolean property was my initial approach then Andy and Wolfram Sang suggested the use of compatible strings and later It was suggested to use a property to select mode but I can do it again if it's the best way.
>>> Can you please tell me where should it be documented?
>>
>> bindings/i2c/i2c.txt.
>>
>> Actually, looking at this some more, we already have a way to describe the controller being a slave device with the I2C_OWN_SLAVE_ADDRESS flag in the reg property. We should just need a helper to read reg property of each child and check for the bit set.
>>
>> Rob

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#1546421

On Thu, 2016-12-22 at 14:59 +0000, Luis Oliveira wrote:
> On 13-Dec-16 14:11, Rob Herring wrote:

> > Something like this:
> > 
> > of_for_each_child_node(child) {
> >   of_property_read_u32(child, "reg", &reg);
> >   if (reg & I2C_OWN_SLAVE_ADDRESS))
> >     im_a_slave = true;
> > }
> > 
> > ...rather than testing "mode" is equal to "slave".
> > 
> > Rob
> > 
> 
> Hi Rob, Andy,
> 
> I'm struggling to implement your suggestion @Rob. I checked the
> tegra124-jetson-tk1.dts that uses that approach but I have some
> doubts.
> 
> My DT is as follows
> 
> 	i2c@0x2000 {
>                         compatible = "snps,designware-i2c";
>                         reg = <0x2000 0x100>;
>                         clock-frequency = <400000>;
>                         clocks = <&i2cclk>;
>                         interrupts = <0>;
> 
> I could add something like this:
> 
> 			eeprom@64 {
> 				compatible = "linux,slave-24c02";
> 				reg = <(I2C_OWN_SLAVE_ADDRESS | 0x64)>;
> 			}
> 
> But I think this is different form what I was doing before. I have two
> questions:
> 
> - This way the I2C controller is identified as a slave controller or
> just the
> subnode eeprom?
> - This way looks like my slave address will be fixed
> 
> In the previous Patch v3 submission @Andy suggested a property that
> selects mode
> that I did and it's working. And you @Rob suggested to do it a common
> property.
> It is implemented in the DT like:
> 
> 			mode = "slave";
> 
> So before I do this changes can you please agree both if you still
> think this is
> the best approach?

I'm a bit lost in the discussion (and TBH busy by something else), so I
would agree on whatever you and Rob make an agreement on.

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

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