[PATCH v2 1/3] spi: atmel: simplify MR register update in cs_activate()

[PATCH v2 1/3] spi: atmel: simplify MR register update in cs_activate()

[Manikandan Muralidharan]

simplified the MR register configuration by updating only the PCS field
using SPI_BFINS() instead of rewriting the entire register.
Avoids code duplication.

Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
---
changes in v2:
 - Fixed mail threading
---
 drivers/spi/spi-atmel.c | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
index 89a6b46cd319..409f544d8983 100644
--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -397,20 +397,10 @@ static void cs_activate(struct atmel_spi *as, struct spi_device *spi)
 		 * on CS1,2,3 needs SPI_CSR0.BITS config as SPI_CSR1,2,3.BITS
 		 */
 		spi_writel(as, CSR0, asd->csr);
-		if (as->caps.has_wdrbt) {
-			spi_writel(as, MR,
-					SPI_BF(PCS, ~(0x01 << chip_select))
-					| SPI_BIT(WDRBT)
-					| SPI_BIT(MODFDIS)
-					| SPI_BIT(MSTR));
-		} else {
-			spi_writel(as, MR,
-					SPI_BF(PCS, ~(0x01 << chip_select))
-					| SPI_BIT(MODFDIS)
-					| SPI_BIT(MSTR));
-		}
 
 		mr = spi_readl(as, MR);
+		mr = SPI_BFINS(PCS, ~(0x01 << chip_select), mr);
+		spi_writel(as, MR, mr);
 
 		/*
 		 * Ensures the clock polarity is valid before we actually

base-commit: 4b290aae788e06561754b28c6842e4080957d3f7
-- 
2.25.1

[PATCH v2 2/3] spi: dt-bindings: atmel,at91rm9200-spi: Add support for optional 'spi_gclk' clock

[Manikandan Muralidharan]

Update the Atmel SPI DT binding to support an optional programmable
SPI generic clock 'spi_gclk', in addition to the required 'spi_clk'.

Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
---
changes in v2:
 - Fixed mail threading
---
 .../devicetree/bindings/spi/atmel,at91rm9200-spi.yaml | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/spi/atmel,at91rm9200-spi.yaml b/Documentation/devicetree/bindings/spi/atmel,at91rm9200-spi.yaml
index d29772994cf5..11885d0cc209 100644
--- a/Documentation/devicetree/bindings/spi/atmel,at91rm9200-spi.yaml
+++ b/Documentation/devicetree/bindings/spi/atmel,at91rm9200-spi.yaml
@@ -31,11 +31,16 @@ properties:
     maxItems: 1
 
   clock-names:
-    contains:
-      const: spi_clk
+    items:
+      - const: spi_clk
+      - const: spi_gclk
+    minItems: 1
 
   clocks:
-    maxItems: 1
+    items:
+      - description: Peripheral Bus clock
+      - description: Programmable Generic clock
+    minItems: 1
 
   dmas:
     items:
-- 
2.25.1

[PATCH v2 3/3] spi: atmel: Add support for handling GCLK as a clock source

[Manikandan Muralidharan]

The SPI peripheral clock is typically used to derive the serial
clock (SPCK) via the FLEX_SPI_CSRx.SCBR field. However, on platforms
like the SAM9X7 SoC, where the peripheral clock can reach up to 266 MHz,
this may exceed the SCBR limit, causing SPI transfers to fail.
This patch adds support for using the SPI Generic Clock (GCLK) as an
alternative and more flexible clock source for SPCK generation.
The FLEX_SPI_MR.BRSRCCLK bit is updated accordingly to select between the
peripheral clock and GCLK.

Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
---
changes in v2:
 - Fixed mail threading
---
 drivers/spi/spi-atmel.c | 64 +++++++++++++++++++++++++++++++++++------
 1 file changed, 56 insertions(+), 8 deletions(-)

diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
index 409f544d8983..89977bff76d2 100644
--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -256,6 +256,7 @@ struct atmel_spi {
 	void __iomem		*regs;
 	int			irq;
 	struct clk		*clk;
+	struct clk		*gclk;
 	struct platform_device	*pdev;
 	unsigned long		spi_clk;
 
@@ -1480,6 +1481,8 @@ static void atmel_get_caps(struct atmel_spi *as)
 
 static void atmel_spi_init(struct atmel_spi *as)
 {
+	u32 mr = 0;
+
 	spi_writel(as, CR, SPI_BIT(SWRST));
 	spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
 
@@ -1487,12 +1490,17 @@ static void atmel_spi_init(struct atmel_spi *as)
 	if (as->fifo_size)
 		spi_writel(as, CR, SPI_BIT(FIFOEN));
 
-	if (as->caps.has_wdrbt) {
-		spi_writel(as, MR, SPI_BIT(WDRBT) | SPI_BIT(MODFDIS)
-				| SPI_BIT(MSTR));
-	} else {
-		spi_writel(as, MR, SPI_BIT(MSTR) | SPI_BIT(MODFDIS));
-	}
+	/*
+	 * If GCLK is selected as the source clock for the bit rate generation
+	 * Enable the BRSRCCLK/FDIV/DIV32 bit
+	 */
+	if (as->gclk)
+		mr |= SPI_BIT(FDIV);
+
+	if (as->caps.has_wdrbt)
+		mr |= SPI_BIT(WDRBT);
+
+	spi_writel(as, MR, mr | SPI_BIT(MODFDIS) | SPI_BIT(MSTR));
 
 	if (as->use_pdc)
 		spi_writel(as, PTCR, SPI_BIT(RXTDIS) | SPI_BIT(TXTDIS));
@@ -1555,6 +1563,11 @@ static int atmel_spi_probe(struct platform_device *pdev)
 	as->phybase = regs->start;
 	as->irq = irq;
 	as->clk = clk;
+	as->gclk = devm_clk_get_optional(&pdev->dev, "spi_gclk");
+	if (IS_ERR(as->gclk)) {
+		ret = PTR_ERR(as->gclk);
+		goto out_unmap_regs;
+	}
 
 	init_completion(&as->xfer_completion);
 
@@ -1615,7 +1628,19 @@ static int atmel_spi_probe(struct platform_device *pdev)
 	if (ret)
 		goto out_free_irq;
 
-	as->spi_clk = clk_get_rate(clk);
+	/*
+	 * In cases where the peripheral clock is higher,the FLEX_SPI_CSRx.SCBR
+	 * exceeds the threshold (SCBR ≤ 255), the GCLK is used as the source clock
+	 * for the SPCK (SPI Serial Clock) bit rate generation
+	 */
+	if (as->gclk) {
+		ret = clk_prepare_enable(as->gclk);
+		if (ret)
+			goto out_disable_clk;
+		as->spi_clk = clk_get_rate(as->gclk);
+	} else {
+		as->spi_clk = clk_get_rate(clk);
+	}
 
 	as->fifo_size = 0;
 	if (!of_property_read_u32(pdev->dev.of_node, "atmel,fifo-size",
@@ -1650,6 +1675,8 @@ static int atmel_spi_probe(struct platform_device *pdev)
 
 	spi_writel(as, CR, SPI_BIT(SWRST));
 	spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
+	clk_disable_unprepare(as->gclk);
+out_disable_clk:
 	clk_disable_unprepare(clk);
 out_free_irq:
 out_unmap_regs:
@@ -1685,6 +1712,8 @@ static void atmel_spi_remove(struct platform_device *pdev)
 	spin_unlock_irq(&as->lock);
 
 	clk_disable_unprepare(as->clk);
+	if (as->gclk)
+		clk_disable_unprepare(as->gclk);
 
 	pm_runtime_put_noidle(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
@@ -1696,6 +1725,8 @@ static int atmel_spi_runtime_suspend(struct device *dev)
 	struct atmel_spi *as = spi_controller_get_devdata(host);
 
 	clk_disable_unprepare(as->clk);
+	if (as->gclk)
+		clk_disable_unprepare(as->gclk);
 	pinctrl_pm_select_sleep_state(dev);
 
 	return 0;
@@ -1705,10 +1736,20 @@ static int atmel_spi_runtime_resume(struct device *dev)
 {
 	struct spi_controller *host = dev_get_drvdata(dev);
 	struct atmel_spi *as = spi_controller_get_devdata(host);
+	int ret;
 
 	pinctrl_pm_select_default_state(dev);
 
-	return clk_prepare_enable(as->clk);
+	ret = clk_prepare_enable(as->clk);
+	if (ret)
+		return ret;
+	if (as->gclk) {
+		ret = clk_prepare_enable(as->gclk);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
 }
 
 static int atmel_spi_suspend(struct device *dev)
@@ -1736,10 +1777,17 @@ static int atmel_spi_resume(struct device *dev)
 	ret = clk_prepare_enable(as->clk);
 	if (ret)
 		return ret;
+	if (as->gclk) {
+		ret = clk_prepare_enable(as->gclk);
+		if (ret)
+			return ret;
+	}
 
 	atmel_spi_init(as);
 
 	clk_disable_unprepare(as->clk);
+	if (as->gclk)
+		clk_disable_unprepare(as->gclk);
 
 	if (!pm_runtime_suspended(dev)) {
 		ret = atmel_spi_runtime_resume(dev);
-- 
2.25.1

Re: [PATCH v2 2/3] spi: dt-bindings: atmel,at91rm9200-spi: Add support for optional 'spi_gclk' clock

[Krzysztof Kozlowski]

On 30/07/2025 12:10, Manikandan Muralidharan wrote:
> Update the Atmel SPI DT binding to support an optional programmable
> SPI generic clock 'spi_gclk', in addition to the required 'spi_clk'.
> 
> Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
> ---
> changes in v2:
>  - Fixed mail threading

You already received comments. Respond to them instead of sending again
the same.

Best regards,
Krzysztof

Re: [PATCH v2 2/3] spi: dt-bindings: atmel,at91rm9200-spi: Add support for optional 'spi_gclk' clock

[Manikandan.M]

Hi Krzysztof,

On 30/07/25 4:51 pm, Krzysztof Kozlowski wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On 30/07/2025 12:10, Manikandan Muralidharan wrote:
>> Update the Atmel SPI DT binding to support an optional programmable
>> SPI generic clock 'spi_gclk', in addition to the required 'spi_clk'.
>>
>> Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
>> ---
>> changes in v2:
>>   - Fixed mail threading
> 
> You already received comments. Respond to them instead of sending again
> the same.
> 

I have re-submitted the series so that patch 3/3 includes a clear 
explanation of this change for the benefit of a wider audience.
Apologies if this patch also requires a brief explanation—please let me 
know if I should include it here.

> Best regards,
> Krzysztof

-- 
Thanks and Regards,
Manikandan M.

Re: [PATCH v2 2/3] spi: dt-bindings: atmel,at91rm9200-spi: Add support for optional 'spi_gclk' clock

[Krzysztof Kozlowski]

On 01/08/2025 05:36, Manikandan.M@microchip.com wrote:
> Hi Krzysztof,
> 
> On 30/07/25 4:51 pm, Krzysztof Kozlowski wrote:
>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>
>> On 30/07/2025 12:10, Manikandan Muralidharan wrote:
>>> Update the Atmel SPI DT binding to support an optional programmable
>>> SPI generic clock 'spi_gclk', in addition to the required 'spi_clk'.
>>>
>>> Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
>>> ---
>>> changes in v2:
>>>   - Fixed mail threading
>>
>> You already received comments. Respond to them instead of sending again
>> the same.
>>
> 
> I have re-submitted the series so that patch 3/3 includes a clear 
> explanation of this change for the benefit of a wider audience.
> Apologies if this patch also requires a brief explanation—please let me 
> know if I should include it here.

I do not see you addressed any comments. There are no changes here
except threading. Look at your changelog:

changes in v2:
   - Fixed mail threading

Best regards,
Krzysztof

Re: [PATCH v2 2/3] spi: dt-bindings: atmel,at91rm9200-spi: Add support for optional 'spi_gclk' clock

[Manikandan.M]

Hi Krzysztof,

On 01/08/25 2:45 pm, Krzysztof Kozlowski wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On 01/08/2025 05:36, Manikandan.M@microchip.com wrote:
>> Hi Krzysztof,
>>
>> On 30/07/25 4:51 pm, Krzysztof Kozlowski wrote:
>>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>>
>>> On 30/07/2025 12:10, Manikandan Muralidharan wrote:
>>>> Update the Atmel SPI DT binding to support an optional programmable
>>>> SPI generic clock 'spi_gclk', in addition to the required 'spi_clk'.
>>>>
>>>> Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
>>>> ---
>>>> changes in v2:
>>>>    - Fixed mail threading
>>>
>>> You already received comments. Respond to them instead of sending again
>>> the same.
>>>
>>
>> I have re-submitted the series so that patch 3/3 includes a clear
>> explanation of this change for the benefit of a wider audience.
>> Apologies if this patch also requires a brief explanation—please let me
>> know if I should include it here.
> 
> I do not see you addressed any comments. There are no changes here
> except threading. Look at your changelog:
> 
My apologies — I’ll provide the explanation for the GCLK change in patch 
2/3 and submit v3.

"The Atmel SPI controller supports both the peripheral clock and the 
Generic Clock (GCLK) as sources for SPCK generation. On platforms like 
the SAM9X7 SoC, the peripheral clock can reach frequencies up to 
266 MHz. This may exceed the maximum value supported by the Serial Clock 
Baud Rate (SCBR) divider, leading to SPI transfer failures. In such 
cases, the GCLK can be used as an alternative source for SPCK generation"

> changes in v2:
>     - Fixed mail threading
> 
> Best regards,
> Krzysztof

-- 
Thanks and Regards,
Manikandan M.

Re: [PATCH v2 1/3] spi: atmel: simplify MR register update in cs_activate()

[Mark Brown]

On Wed, 30 Jul 2025 15:40:13 +0530, Manikandan Muralidharan wrote:
> simplified the MR register configuration by updating only the PCS field
> using SPI_BFINS() instead of rewriting the entire register.
> Avoids code duplication.
> 
> 

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/3] spi: atmel: simplify MR register update in cs_activate()
      commit: 379f819733f28b5aa1802f3ede442f08b7275f4e
[2/3] spi: dt-bindings: atmel,at91rm9200-spi: Add support for optional 'spi_gclk' clock
      commit: a673ebd0a2a587f3d6b923d59d363fc9e8a9f920
[3/3] spi: atmel: Add support for handling GCLK as a clock source
      commit: 91e5722baaea06c1f1b105e9e3fd6645dbdd938b

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark