[PATCH 0/2] i2c: at91: Add support for programmable clock source

[PATCH 0/2] i2c: at91: Add support for programmable clock source

[Horatiu Vultur]

Add support to be able to set BRSRCCLK. This feature is support on lan966x

Horatiu Vultur (2):
  dt-bindings: i2c: at91: Extend compatible list for lan966x
  i2c: at91: add support for brsrcclk

 .../devicetree/bindings/i2c/i2c-at91.txt      |  6 +++--
 drivers/i2c/busses/i2c-at91-core.c            | 16 +++++++++++++
 drivers/i2c/busses/i2c-at91-master.c          | 23 +++++++++++++++++--
 drivers/i2c/busses/i2c-at91.h                 |  1 +
 4 files changed, 42 insertions(+), 4 deletions(-)

-- 
2.33.0

[PATCH 1/2] dt-bindings: i2c: at91: Extend compatible list for lan966x

[Horatiu Vultur]

Extend compatible list and the i2c-sda-hold-time-ns property
with 'microchip,lan966x-i2c'

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
---
 Documentation/devicetree/bindings/i2c/i2c-at91.txt | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-at91.txt b/Documentation/devicetree/bindings/i2c/i2c-at91.txt
index 2015f50aed0f..d3b5ed081597 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-at91.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-at91.txt
@@ -10,7 +10,8 @@ Required properties :
 	"atmel,at91sam9x5-i2c",
 	"atmel,sama5d4-i2c",
 	"atmel,sama5d2-i2c",
-	"microchip,sam9x60-i2c".
+	"microchip,sam9x60-i2c",
+	"microchip,lan966x-i2c".
 - reg: physical base address of the controller and length of memory mapped
      region.
 - interrupts: interrupt number to the cpu.
@@ -27,7 +28,8 @@ Optional properties:
 - i2c-sda-hold-time-ns: TWD hold time, only available for:
 	"atmel,sama5d4-i2c",
 	"atmel,sama5d2-i2c",
-	"microchip,sam9x60-i2c".
+	"microchip,sam9x60-i2c",
+	"microchip,lan966x-i2c".
 - scl-gpios: specify the gpio related to SCL pin
 - sda-gpios: specify the gpio related to SDA pin
 - pinctrl: add extra pinctrl to configure i2c pins to gpio function for i2c
-- 
2.33.0

Re: [PATCH 1/2] dt-bindings: i2c: at91: Extend compatible list for lan966x

[Rob Herring]

On Tue, 12 Oct 2021 16:07:17 +0200, Horatiu Vultur wrote:
> Extend compatible list and the i2c-sda-hold-time-ns property
> with 'microchip,lan966x-i2c'
> 
> Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
> ---
>  Documentation/devicetree/bindings/i2c/i2c-at91.txt | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 

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

[PATCH 2/2] i2c: at91: add support for brsrcclk

[Horatiu Vultur]

This allows to set the TWI bite rate based on a programmable clock source.
The lan966x supports this feature.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
---
 drivers/i2c/busses/i2c-at91-core.c   | 16 ++++++++++++++++
 drivers/i2c/busses/i2c-at91-master.c | 23 +++++++++++++++++++++--
 drivers/i2c/busses/i2c-at91.h        |  1 +
 3 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-at91-core.c b/drivers/i2c/busses/i2c-at91-core.c
index 2df9df585131..d98b437e5775 100644
--- a/drivers/i2c/busses/i2c-at91-core.c
+++ b/drivers/i2c/busses/i2c-at91-core.c
@@ -146,6 +146,19 @@ static struct at91_twi_pdata sam9x60_config = {
 	.has_clear_cmd = true,
 };
 
+static struct at91_twi_pdata lan966x_config = {
+	.clk_max_div = 7,
+	.clk_offset = 0,
+	.clk_brsrcclk = true,
+	.has_unre_flag = true,
+	.has_alt_cmd = true,
+	.has_hold_field = true,
+	.has_dig_filtr = true,
+	.has_adv_dig_filtr = true,
+	.has_ana_filtr = true,
+	.has_clear_cmd = true,
+};
+
 static const struct of_device_id atmel_twi_dt_ids[] = {
 	{
 		.compatible = "atmel,at91rm9200-i2c",
@@ -174,6 +187,9 @@ static const struct of_device_id atmel_twi_dt_ids[] = {
 	}, {
 		.compatible = "microchip,sam9x60-i2c",
 		.data = &sam9x60_config,
+	}, {
+		.compatible = "microchip,lan966x-i2c",
+		.data = &lan966x_config,
 	}, {
 		/* sentinel */
 	}
diff --git a/drivers/i2c/busses/i2c-at91-master.c b/drivers/i2c/busses/i2c-at91-master.c
index b0eae94909f4..f504af30adbe 100644
--- a/drivers/i2c/busses/i2c-at91-master.c
+++ b/drivers/i2c/busses/i2c-at91-master.c
@@ -120,8 +120,27 @@ static void at91_calc_twi_clock(struct at91_twi_dev *dev)
 		}
 	}
 
-	dev->twi_cwgr_reg = (ckdiv << 16) | (cdiv << 8) | cdiv
-			    | AT91_TWI_CWGR_HOLD(hold);
+	if (pdata->clk_brsrcclk) {
+		u8 chdiv, cldiv, gck_pr;
+
+		gck_pr = 1000000000 / clk_get_rate(dev->clk);
+
+		/* thigh = bus_freq_hz in ns * 0.4
+		 * tlow = bus_freq_hz in ns * 0.6
+		 * chdiv = (thigh / GCK_PR)/2 ^ CKDIV
+		 * cldiv = (tlow / GCK_PR)/2 ^ CKDIV
+		 * where ckdiv = 0;
+		 */
+		cldiv = (1000000000 / t->bus_freq_hz * 6 / 10) / gck_pr;
+		chdiv = (1000000000 / t->bus_freq_hz * 4 / 10) / gck_pr;
+
+		dev->twi_cwgr_reg = (chdiv << 8) | cldiv
+			| AT91_TWI_CWGR_HOLD(hold)
+			| pdata->clk_brsrcclk << 20;
+	} else {
+		dev->twi_cwgr_reg = (ckdiv << 16) | (cdiv << 8) | cdiv
+			| AT91_TWI_CWGR_HOLD(hold);
+	}
 
 	dev->filter_width = filter_width;
 
diff --git a/drivers/i2c/busses/i2c-at91.h b/drivers/i2c/busses/i2c-at91.h
index 942e9c3973bb..f7328fbe8eb8 100644
--- a/drivers/i2c/busses/i2c-at91.h
+++ b/drivers/i2c/busses/i2c-at91.h
@@ -115,6 +115,7 @@
 struct at91_twi_pdata {
 	unsigned clk_max_div;
 	unsigned clk_offset;
+	bool clk_brsrcclk;
 	bool has_unre_flag;
 	bool has_alt_cmd;
 	bool has_hold_field;
-- 
2.33.0

Re: [PATCH 0/2] i2c: at91: Add support for programmable clock source

[Codrin.Ciubotariu]

On 12.10.2021 17:07, Horatiu Vultur wrote:
> Add support to be able to set BRSRCCLK. This feature is support on lan966x
> 
> Horatiu Vultur (2):
>    dt-bindings: i2c: at91: Extend compatible list for lan966x
>    i2c: at91: add support for brsrcclk
> 
>   .../devicetree/bindings/i2c/i2c-at91.txt      |  6 +++--
>   drivers/i2c/busses/i2c-at91-core.c            | 16 +++++++++++++
>   drivers/i2c/busses/i2c-at91-master.c          | 23 +++++++++++++++++--
>   drivers/i2c/busses/i2c-at91.h                 |  1 +
>   4 files changed, 42 insertions(+), 4 deletions(-)
> 

Hi Horatiu,

 From what I understand, on your DTS, you replaced the peripheral clock 
with the GCLK in the I2C node. This means that you are forcing all the 
variants that support clk_brsrcclk to treat the current clock as GCLK. 
This is not necessarily correct, since this newer variants can also work 
fine with only the peripheral clock and we should keep these option 
available.

I would add an optional GCLK clock binding in the I2C node. This way 
GCLK will be used only if it is present in DT and clk_brsrcclk set.

Best regards,
Codrin

Re: [PATCH 0/2] i2c: at91: Add support for programmable clock source

[Horatiu Vultur - M31836]

The 10/13/2021 08:49, Codrin Ciubotariu - M19940 wrote:
> On 12.10.2021 17:07, Horatiu Vultur wrote:
> > Add support to be able to set BRSRCCLK. This feature is support on lan966x
> > 
> > Horatiu Vultur (2):
> >    dt-bindings: i2c: at91: Extend compatible list for lan966x
> >    i2c: at91: add support for brsrcclk
> > 
> >   .../devicetree/bindings/i2c/i2c-at91.txt      |  6 +++--
> >   drivers/i2c/busses/i2c-at91-core.c            | 16 +++++++++++++
> >   drivers/i2c/busses/i2c-at91-master.c          | 23 +++++++++++++++++--
> >   drivers/i2c/busses/i2c-at91.h                 |  1 +
> >   4 files changed, 42 insertions(+), 4 deletions(-)
> > 
> 
> Hi Horatiu,

Hi Codrin,

> 
>  From what I understand, on your DTS, you replaced the peripheral clock 
> with the GCLK in the I2C node. This means that you are forcing all the 
> variants that support clk_brsrcclk to treat the current clock as GCLK. 
> This is not necessarily correct, since this newer variants can also work 
> fine with only the peripheral clock and we should keep these option 
> available.
> 
> I would add an optional GCLK clock binding in the I2C node. This way 
> GCLK will be used only if it is present in DT and clk_brsrcclk set.

Thanks for the explanation.

I think actually I will drop this patch series because apparently
lan966x works fine also with the peripheral clock. So then no changes
are required.

If you think is worth it, I can do another version with the proposed
changes.

> 
> Best regards,
> Codrin

-- 
/Horatiu

Re: [PATCH 0/2] i2c: at91: Add support for programmable clock source

[Codrin.Ciubotariu]

> I think actually I will drop this patch series because apparently
> lan966x works fine also with the peripheral clock. So then no changes
> are required.
> 
> If you think is worth it, I can do another version with the proposed
> changes.

Probably not until we have an implemented good reason to use GCLK.

Best regards,
Codrin

Re: [PATCH 0/2] i2c: at91: Add support for programmable clock source

[Wolfram Sang]

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> I think actually I will drop this patch series because apparently
> lan966x works fine also with the peripheral clock. So then no changes
> are required.

Not even patch 1/2?


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Re: [PATCH 0/2] i2c: at91: Add support for programmable clock source

[Codrin.Ciubotariu]

On 05.11.2021 23:47, Wolfram Sang wrote:
> 
>> I think actually I will drop this patch series because apparently
>> lan966x works fine also with the peripheral clock. So then no changes
>> are required.
> 
> Not even patch 1/2?
> 

we can keep the new compatible, but patch 2/2 needs to be split.

Best regards,
Codrin

Re: [PATCH 0/2] i2c: at91: Add support for programmable clock source

[Horatiu Vultur - M31836]

The 11/08/2021 08:35, Codrin Ciubotariu - M19940 wrote:
> On 05.11.2021 23:47, Wolfram Sang wrote:
> > 
> >> I think actually I will drop this patch series because apparently
> >> lan966x works fine also with the peripheral clock. So then no changes
> >> are required.
> > 
> > Not even patch 1/2?
> > 
> 
> we can keep the new compatible, but patch 2/2 needs to be split.

For me it is OK to use the compatible string 'microchip,sam9x60-i2c'

> 
> Best regards,
> Codrin

-- 
/Horatiu

Re: [PATCH 0/2] i2c: at91: Add support for programmable clock source

[Wolfram Sang]

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> > > Not even patch 1/2?
> > 
> > we can keep the new compatible, but patch 2/2 needs to be split.
> 
> For me it is OK to use the compatible string 'microchip,sam9x60-i2c'

I'll drop this patch for now. If anyone is still interested in it,
please resend.


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