[PATCH 0/4] Enable multiple MCAN on AM62x

[PATCH 0/4] Enable multiple MCAN on AM62x

[Judith Mendez]

On AM62x there is one MCAN in MAIN domain and two in MCU domain.
The MCANs in MCU domain were not enabled since there is no
hardware interrupt routed to A53 GIC interrupt controller.
Therefore A53 Linux cannot be interrupted by MCU MCANs.

This solution instantiates a hrtimer with 1 ms polling interval
for a MCAN when there is no hardware interrupt. This hrtimer
generates a recurring software interrupt which allows to call the
isr. The isr will check if there is pending transaction by reading
a register and proceed normally if there is.

On AM62x this series enables two MCU MCAN which will use the hrtimer
implementation. MCANs with hardware interrupt routed to A53 Linux
will continue to use the hardware interrupt as expected.

Timer polling method was tested on both classic CAN and CAN-FD
at 125 KBPS, 250 KBPS, 1 MBPS and 2.5 MBPS with 4 MBPS bitrate
switching.

Letency and CPU load benchmarks were tested on 3x MCAN on AM62x.
1 MBPS timer polling interval is the better timer polling interval
since it has comparable latency to hardware interrupt with the worse
case being 1ms + CAN frame propagation time and CPU load is not
substantial. Latency can be improved further with less than 1 ms
polling intervals, howerver it is at the cost of CPU usage since CPU
load increases at 0.5 ms and lower polling periods than 1ms.

Note that in terms of power, enabling MCU MCANs with timer-polling
implementation might have negative impact since we will have to wake
up every 1 ms whether there are CAN packets pending in the RX FIFO or
not. This might prevent the CPU from entering into deeper idle states
for extended periods of time.

This patch series depends on 'Enable CAN PHY transceiver driver':
https://lore.kernel.org/lkml/775ec9ce-7668-429c-a977-6c8995968d6e@app.fastmail.com/T/

Previously sent an RFC:
https://lore.kernel.org/linux-can/52a37e51-4143-9017-42ee-8d17c67028e3@ti.com/T/#t

Judith Mendez (4):
  can: m_can: Add hrtimer to generate software interrupt
  dt-bindings: net: can: Make interrupt attributes optional for MCAN
  arm64: dts: ti: Add AM62x MCAN MAIN domain transceiver overlay
  arm64: dts: ti: Enable MCU MCANs for AM62x

 .../bindings/net/can/bosch,m_can.yaml         |  2 -
 arch/arm64/boot/dts/ti/Makefile               |  2 +
 arch/arm64/boot/dts/ti/k3-am62-mcu.dtsi       | 24 ++++++++
 .../boot/dts/ti/k3-am625-sk-mcan-main.dtso    | 35 ++++++++++++
 .../boot/dts/ti/k3-am625-sk-mcan-mcu.dtso     | 55 +++++++++++++++++++
 drivers/net/can/m_can/m_can.c                 | 30 +++++++++-
 drivers/net/can/m_can/m_can.h                 |  3 +
 drivers/net/can/m_can/m_can_platform.c        | 13 ++++-
 8 files changed, 158 insertions(+), 6 deletions(-)
 create mode 100644 arch/arm64/boot/dts/ti/k3-am625-sk-mcan-main.dtso
 create mode 100644 arch/arm64/boot/dts/ti/k3-am625-sk-mcan-mcu.dtso

-- 
2.17.1

[PATCH 1/4] can: m_can: Add hrtimer to generate software interrupt

[Judith Mendez]

Add an hrtimer to MCAN struct. Each MCAN will have its own
hrtimer instantiated if there is no hardware interrupt found.

The hrtimer will generate a software interrupt every 1 ms. In
hrtimer callback, we check if there is a transaction pending by
reading a register, then process by calling the isr if there is.

Signed-off-by: Judith Mendez <jm@ti.com>
---
 drivers/net/can/m_can/m_can.c          | 30 ++++++++++++++++++++++++--
 drivers/net/can/m_can/m_can.h          |  3 +++
 drivers/net/can/m_can/m_can_platform.c | 13 +++++++++--
 3 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index a5003435802b..8784bdea300a 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -23,6 +23,7 @@
 #include <linux/pinctrl/consumer.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/hrtimer.h>
 
 #include "m_can.h"
 
@@ -1587,6 +1588,11 @@ static int m_can_close(struct net_device *dev)
 	if (!cdev->is_peripheral)
 		napi_disable(&cdev->napi);
 
+	if (dev->irq < 0) {
+		dev_dbg(cdev->dev, "Disabling the hrtimer\n");
+		hrtimer_cancel(&cdev->hrtimer);
+	}
+
 	m_can_stop(dev);
 	m_can_clk_stop(cdev);
 	free_irq(dev->irq, dev);
@@ -1793,6 +1799,18 @@ static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
 	return NETDEV_TX_OK;
 }
 
+enum hrtimer_restart hrtimer_callback(struct hrtimer *timer)
+{
+	struct m_can_classdev *cdev =
+		container_of(timer, struct m_can_classdev, hrtimer);
+
+	m_can_isr(0, cdev->net);
+
+	hrtimer_forward_now(timer, ms_to_ktime(1));
+
+	return HRTIMER_RESTART;
+}
+
 static int m_can_open(struct net_device *dev)
 {
 	struct m_can_classdev *cdev = netdev_priv(dev);
@@ -1827,13 +1845,21 @@ static int m_can_open(struct net_device *dev)
 		}
 
 		INIT_WORK(&cdev->tx_work, m_can_tx_work_queue);
-
 		err = request_threaded_irq(dev->irq, NULL, m_can_isr,
 					   IRQF_ONESHOT,
 					   dev->name, dev);
+
 	} else {
-		err = request_irq(dev->irq, m_can_isr, IRQF_SHARED, dev->name,
+		if (dev->irq > 0)	{
+			err = request_irq(dev->irq, m_can_isr, IRQF_SHARED, dev->name,
 				  dev);
+		}
+
+		else	{
+			dev_dbg(cdev->dev, "Enabling the hrtimer\n");
+			cdev->hrtimer.function = &hrtimer_callback;
+			hrtimer_start(&cdev->hrtimer, ns_to_ktime(0), HRTIMER_MODE_REL_PINNED);
+		}
 	}
 
 	if (err < 0) {
diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
index a839dc71dc9b..ed046d77fdb9 100644
--- a/drivers/net/can/m_can/m_can.h
+++ b/drivers/net/can/m_can/m_can.h
@@ -28,6 +28,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/slab.h>
 #include <linux/uaccess.h>
+#include <linux/hrtimer.h>
 
 /* m_can lec values */
 enum m_can_lec_type {
@@ -93,6 +94,8 @@ struct m_can_classdev {
 	int is_peripheral;
 
 	struct mram_cfg mcfg[MRAM_CFG_NUM];
+
+	struct hrtimer hrtimer;
 };
 
 struct m_can_classdev *m_can_class_allocate_dev(struct device *dev, int sizeof_priv);
diff --git a/drivers/net/can/m_can/m_can_platform.c b/drivers/net/can/m_can/m_can_platform.c
index 9c1dcf838006..7540db74b7d0 100644
--- a/drivers/net/can/m_can/m_can_platform.c
+++ b/drivers/net/can/m_can/m_can_platform.c
@@ -7,6 +7,7 @@
 
 #include <linux/phy/phy.h>
 #include <linux/platform_device.h>
+#include <linux/hrtimer.h>
 
 #include "m_can.h"
 
@@ -98,8 +99,16 @@ static int m_can_plat_probe(struct platform_device *pdev)
 	addr = devm_platform_ioremap_resource_byname(pdev, "m_can");
 	irq = platform_get_irq_byname(pdev, "int0");
 	if (IS_ERR(addr) || irq < 0) {
-		ret = -EINVAL;
-		goto probe_fail;
+		if (irq == -EPROBE_DEFER) {
+			ret = -EPROBE_DEFER;
+			goto probe_fail;
+		}
+		if (IS_ERR(addr)) {
+			ret = PTR_ERR(addr);
+			goto probe_fail;
+		}
+		dev_dbg(mcan_class->dev, "Failed to get irq, initialize hrtimer\n");
+		hrtimer_init(&mcan_class->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_PINNED);
 	}
 
 	/* message ram could be shared */
-- 
2.17.1

Re: [PATCH 1/4] can: m_can: Add hrtimer to generate software interrupt

[Marc Kleine-Budde]

[-- Attachment #1: Type: text/plain, Size: 5852 bytes --]

On 19.04.2023 17:33:20, Judith Mendez wrote:
> Add an hrtimer to MCAN struct. Each MCAN will have its own
> hrtimer instantiated if there is no hardware interrupt found.
> 
> The hrtimer will generate a software interrupt every 1 ms. In
> hrtimer callback, we check if there is a transaction pending by
> reading a register, then process by calling the isr if there is.
> 
> Signed-off-by: Judith Mendez <jm@ti.com>
> ---
>  drivers/net/can/m_can/m_can.c          | 30 ++++++++++++++++++++++++--
>  drivers/net/can/m_can/m_can.h          |  3 +++
>  drivers/net/can/m_can/m_can_platform.c | 13 +++++++++--
>  3 files changed, 42 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index a5003435802b..8784bdea300a 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -23,6 +23,7 @@
>  #include <linux/pinctrl/consumer.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/hrtimer.h>
>  
>  #include "m_can.h"
>  
> @@ -1587,6 +1588,11 @@ static int m_can_close(struct net_device *dev)
>  	if (!cdev->is_peripheral)
>  		napi_disable(&cdev->napi);
>  
> +	if (dev->irq < 0) {
> +		dev_dbg(cdev->dev, "Disabling the hrtimer\n");
> +		hrtimer_cancel(&cdev->hrtimer);
> +	}
> +
>  	m_can_stop(dev);
>  	m_can_clk_stop(cdev);
>  	free_irq(dev->irq, dev);
> @@ -1793,6 +1799,18 @@ static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
>  	return NETDEV_TX_OK;
>  }
>  
> +enum hrtimer_restart hrtimer_callback(struct hrtimer *timer)
> +{
> +	struct m_can_classdev *cdev =
> +		container_of(timer, struct m_can_classdev, hrtimer);
> +
> +	m_can_isr(0, cdev->net);
> +
> +	hrtimer_forward_now(timer, ms_to_ktime(1));
> +
> +	return HRTIMER_RESTART;
> +}
> +
>  static int m_can_open(struct net_device *dev)
>  {
>  	struct m_can_classdev *cdev = netdev_priv(dev);
> @@ -1827,13 +1845,21 @@ static int m_can_open(struct net_device *dev)
>  		}
>  
>  		INIT_WORK(&cdev->tx_work, m_can_tx_work_queue);
> -
>  		err = request_threaded_irq(dev->irq, NULL, m_can_isr,
>  					   IRQF_ONESHOT,
>  					   dev->name, dev);
> +

nitpick:
Please remove these 2 newline changes.

>  	} else {
> -		err = request_irq(dev->irq, m_can_isr, IRQF_SHARED, dev->name,
> +		if (dev->irq > 0)	{

Please follow the kernel coding style and use a space not a tab after
the closing ")" of the "if".

> +			err = request_irq(dev->irq, m_can_isr, IRQF_SHARED, dev->name,
>  				  dev);
> +		}
> +
> +		else	{

Please use kernel coding style: "} else {"

> +			dev_dbg(cdev->dev, "Enabling the hrtimer\n");
> +			cdev->hrtimer.function = &hrtimer_callback;
> +			hrtimer_start(&cdev->hrtimer, ns_to_ktime(0), HRTIMER_MODE_REL_PINNED);
> +		}

I think there's no need to have nested else branches, what about this
approach?

--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1831,9 +1831,11 @@ static int m_can_open(struct net_device *dev)
                 err = request_threaded_irq(dev->irq, NULL, m_can_isr,
                                            IRQF_ONESHOT,
                                            dev->name, dev);
-        } else {
+        } else if (dev->irq) {
                 err = request_irq(dev->irq, m_can_isr, IRQF_SHARED, dev->name,
                                   dev);
+        } else {
+                // polling
         }
 
         if (err < 0) {

>  	}
>  
>  	if (err < 0) {
> diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
> index a839dc71dc9b..ed046d77fdb9 100644
> --- a/drivers/net/can/m_can/m_can.h
> +++ b/drivers/net/can/m_can/m_can.h
> @@ -28,6 +28,7 @@
>  #include <linux/pm_runtime.h>
>  #include <linux/slab.h>
>  #include <linux/uaccess.h>
> +#include <linux/hrtimer.h>
>  
>  /* m_can lec values */
>  enum m_can_lec_type {
> @@ -93,6 +94,8 @@ struct m_can_classdev {
>  	int is_peripheral;
>  
>  	struct mram_cfg mcfg[MRAM_CFG_NUM];
> +
> +	struct hrtimer hrtimer;
>  };
>  
>  struct m_can_classdev *m_can_class_allocate_dev(struct device *dev, int sizeof_priv);
> diff --git a/drivers/net/can/m_can/m_can_platform.c b/drivers/net/can/m_can/m_can_platform.c
> index 9c1dcf838006..7540db74b7d0 100644
> --- a/drivers/net/can/m_can/m_can_platform.c
> +++ b/drivers/net/can/m_can/m_can_platform.c
> @@ -7,6 +7,7 @@
>  
>  #include <linux/phy/phy.h>
>  #include <linux/platform_device.h>
> +#include <linux/hrtimer.h>
>  
>  #include "m_can.h"
>  
> @@ -98,8 +99,16 @@ static int m_can_plat_probe(struct platform_device *pdev)
>  	addr = devm_platform_ioremap_resource_byname(pdev, "m_can");
>  	irq = platform_get_irq_byname(pdev, "int0");
>  	if (IS_ERR(addr) || irq < 0) {
> -		ret = -EINVAL;
> -		goto probe_fail;
> +		if (irq == -EPROBE_DEFER) {
> +			ret = -EPROBE_DEFER;
> +			goto probe_fail;
> +		}
> +		if (IS_ERR(addr)) {
> +			ret = PTR_ERR(addr);
> +			goto probe_fail;
> +		}
> +		dev_dbg(mcan_class->dev, "Failed to get irq, initialize hrtimer\n");
> +		hrtimer_init(&mcan_class->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_PINNED);

Looks better. Please remove the outer "if (IS_ERR(addr) || irq < 0)" and
move the error checking directly after "addr = devm_platform_ioremap_resource_byname()".

What do you think about introducing the "poll-interval" property and
only enable polling if it is set?

>  	}
>  
>  	/* message ram could be shared */
> -- 
> 2.17.1
> 
>

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |

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[PATCH 2/4] dt-bindings: net: can: Make interrupt attributes optional for MCAN

[Judith Mendez]

For MCAN, remove interrupt and interrupt names from the required
section.

On AM62x SoC, MCANs on MCU domain do not have hardware interrupt
routed to A53 Linux, instead they will use software interrupt
by hrtimer. Make interrupt attributes optional in MCAN node
by removing from required section.

Signed-off-by: Judith Mendez <jm@ti.com>
---
 Documentation/devicetree/bindings/net/can/bosch,m_can.yaml | 2 --
 1 file changed, 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml b/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml
index 67879aab623b..43f1aa9addc0 100644
--- a/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml
+++ b/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml
@@ -122,8 +122,6 @@ required:
   - compatible
   - reg
   - reg-names
-  - interrupts
-  - interrupt-names
   - clocks
   - clock-names
   - bosch,mram-cfg
-- 
2.17.1

Re: [PATCH 2/4] dt-bindings: net: can: Make interrupt attributes optional for MCAN

[Marc Kleine-Budde]

[-- Attachment #1: Type: text/plain, Size: 2728 bytes --]

On 19.04.2023 17:33:21, Judith Mendez wrote:
> For MCAN, remove interrupt and interrupt names from the required
> section.
> 
> On AM62x SoC, MCANs on MCU domain do not have hardware interrupt
> routed to A53 Linux, instead they will use software interrupt
> by hrtimer. Make interrupt attributes optional in MCAN node
> by removing from required section.
> 
> Signed-off-by: Judith Mendez <jm@ti.com>

This series basically adds polling support to the driver, which is
needed due to HW limitations.

The proposed logic in the driver is to use polling if
platform_get_irq_byname() fails (due to whatever reason) use polling
with a hard-coded interval.

In the kernel I've found the following properties that describe the
polling interval:

bindings/input/input.yaml:

|   poll-interval:
|     description: Poll interval time in milliseconds.
|     $ref: /schemas/types.yaml#/definitions/uint32


bindings/thermal/thermal-zones.yaml:

|       polling-delay:
|         $ref: /schemas/types.yaml#/definitions/uint32
|         description:
|           The maximum number of milliseconds to wait between polls when
|           checking this thermal zone. Setting this to 0 disables the polling
|           timers setup by the thermal framework and assumes that the thermal
|           sensors in this zone support interrupts.

bindings/regulator/dlg,da9121.yaml

|   dlg,irq-polling-delay-passive-ms:
|     minimum: 1000
|     maximum: 10000
|     description: |
|       Specify the polling period, measured in milliseconds, between interrupt status
|       update checks. Range 1000-10000 ms.

From my point of view the poll-interval from the input subsystem looks
good. Any objections to use it to specify the polling interval for
IRQ-less devices, too?

> ---
>  Documentation/devicetree/bindings/net/can/bosch,m_can.yaml | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml b/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml
> index 67879aab623b..43f1aa9addc0 100644
> --- a/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml
> +++ b/Documentation/devicetree/bindings/net/can/bosch,m_can.yaml
> @@ -122,8 +122,6 @@ required:
>    - compatible
>    - reg
>    - reg-names
> -  - interrupts
> -  - interrupt-names
>    - clocks
>    - clock-names
>    - bosch,mram-cfg
> -- 
> 2.17.1
> 
> 

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |

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Re: [PATCH 2/4] dt-bindings: net: can: Make interrupt attributes optional for MCAN

[Krzysztof Kozlowski]

On 20/04/2023 12:01, Marc Kleine-Budde wrote:
> On 19.04.2023 17:33:21, Judith Mendez wrote:
>> For MCAN, remove interrupt and interrupt names from the required
>> section.
>>
>> On AM62x SoC, MCANs on MCU domain do not have hardware interrupt
>> routed to A53 Linux, instead they will use software interrupt
>> by hrtimer. Make interrupt attributes optional in MCAN node
>> by removing from required section.
>>
>> Signed-off-by: Judith Mendez <jm@ti.com>
> 
> This series basically adds polling support to the driver, which is
> needed due to HW limitations.
> 
> The proposed logic in the driver is to use polling if
> platform_get_irq_byname() fails (due to whatever reason) use polling
> with a hard-coded interval.
> 
> In the kernel I've found the following properties that describe the
> polling interval:
> 
> bindings/input/input.yaml:
> 
> |   poll-interval:
> |     description: Poll interval time in milliseconds.
> |     $ref: /schemas/types.yaml#/definitions/uint32
> 
> 
> bindings/thermal/thermal-zones.yaml:
> 
> |       polling-delay:
> |         $ref: /schemas/types.yaml#/definitions/uint32
> |         description:
> |           The maximum number of milliseconds to wait between polls when
> |           checking this thermal zone. Setting this to 0 disables the polling
> |           timers setup by the thermal framework and assumes that the thermal
> |           sensors in this zone support interrupts.
> 
> bindings/regulator/dlg,da9121.yaml
> 
> |   dlg,irq-polling-delay-passive-ms:
> |     minimum: 1000
> |     maximum: 10000
> |     description: |
> |       Specify the polling period, measured in milliseconds, between interrupt status
> |       update checks. Range 1000-10000 ms.
> 
> From my point of view the poll-interval from the input subsystem looks
> good. Any objections to use it to specify the polling interval for
> IRQ-less devices, too?

Better to skip it, if delay can be figured out by driver based on
something else (e.g. clocks).

Best regards,
Krzysztof

Re: [PATCH 2/4] dt-bindings: net: can: Make interrupt attributes optional for MCAN

[Krzysztof Kozlowski]

On 20/04/2023 00:33, Judith Mendez wrote:
> For MCAN, remove interrupt and interrupt names from the required
> section.
> 
> On AM62x SoC, MCANs on MCU domain do not have hardware interrupt
> routed to A53 Linux, instead they will use software interrupt
> by hrtimer. Make interrupt attributes optional in MCAN node
> by removing from required section.
> 
> Signed-off-by: Judith Mendez <jm@ti.com>
> ---


Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof

[PATCH 3/4] DO_NOT_MERGE arm64: dts: ti: Add AM62x MCAN MAIN domain transceiver overlay

[Judith Mendez]

Add an overlay for main domain MCAN on AM62x SK. The AM62x
SK board does not have on-board CAN transceiver so instead
of changing the DTB permanently, add an overlay to enable
MAIN domain MCAN and support for 1 CAN transceiver.

Signed-off-by: Judith Mendez <jm@ti.com>
---
 arch/arm64/boot/dts/ti/Makefile               |  2 ++
 .../boot/dts/ti/k3-am625-sk-mcan-main.dtso    | 35 +++++++++++++++++++
 2 files changed, 37 insertions(+)
 create mode 100644 arch/arm64/boot/dts/ti/k3-am625-sk-mcan-main.dtso

diff --git a/arch/arm64/boot/dts/ti/Makefile b/arch/arm64/boot/dts/ti/Makefile
index c83c9d772b81..abe15e76b614 100644
--- a/arch/arm64/boot/dts/ti/Makefile
+++ b/arch/arm64/boot/dts/ti/Makefile
@@ -9,8 +9,10 @@
 # alphabetically.
 
 # Boards with AM62x SoC
+k3-am625-sk-mcan-dtbs := k3-am625-sk.dtb k3-am625-sk-mcan-main.dtbo
 dtb-$(CONFIG_ARCH_K3) += k3-am625-beagleplay.dtb
 dtb-$(CONFIG_ARCH_K3) += k3-am625-sk.dtb
+dtb-$(CONFIG_ARCH_K3) += k3-am625-sk-mcan.dtb
 dtb-$(CONFIG_ARCH_K3) += k3-am62-lp-sk.dtb
 
 # Boards with AM62Ax SoC
diff --git a/arch/arm64/boot/dts/ti/k3-am625-sk-mcan-main.dtso b/arch/arm64/boot/dts/ti/k3-am625-sk-mcan-main.dtso
new file mode 100644
index 000000000000..72b68fd51121
--- /dev/null
+++ b/arch/arm64/boot/dts/ti/k3-am625-sk-mcan-main.dtso
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-2.0
+/**
+ * DT overlay for MCAN transceiver in main domain on AM625 SK
+ *
+ * Copyright (C) 2022 Texas Instruments Incorporated - https://www.ti.com/
+ */
+
+/dts-v1/;
+/plugin/;
+
+#include <dt-bindings/pinctrl/k3.h>
+
+&{/} {
+	transceiver1: can-phy0 {
+		compatible = "ti,tcan1042";
+		#phy-cells = <0>;
+		max-bitrate = <5000000>;
+	};
+};
+
+&main_pmx0 {
+	main_mcan0_pins_default: main-mcan0-pins-default {
+		pinctrl-single,pins = <
+			AM62X_IOPAD(0x1dc, PIN_INPUT, 0) /* (E15) MCAN0_RX */
+			AM62X_IOPAD(0x1d8, PIN_OUTPUT, 0) /* (C15) MCAN0_TX */
+		>;
+	};
+};
+
+&main_mcan0 {
+	status = "okay";
+	pinctrl-names = "default";
+	pinctrl-0 = <&main_mcan0_pins_default>;
+	phys = <&transceiver1>;
+};
-- 
2.17.1

[PATCH 4/4] DO_NOT_MERGE arm64: dts: ti: Enable MCU MCANs for AM62x

[Judith Mendez]

On AM62x there are no hardware interrupts routed to GIC interrupt
controller for MCU MCAN IP, A53 Linux cannot receive hardware
interrupts. Since an hrtimer will be used to generate software
interrupts, add MCU MCAN nodes to dtsi and default to disabled.

AM62x does not carry on-board CAN transceivers, so instead of
changing DTB permanently use an overlay to enable MCU MCANs and to
add CAN transceiver nodes.

If an hrtimer is used to generate software interrupts, the two
required interrupt attributes in the MCAN node do not have to be
included.

Signed-off-by: Judith Mendez <jm@ti.com>
---
 arch/arm64/boot/dts/ti/Makefile               |  2 +-
 arch/arm64/boot/dts/ti/k3-am62-mcu.dtsi       | 24 ++++++++
 .../boot/dts/ti/k3-am625-sk-mcan-mcu.dtso     | 55 +++++++++++++++++++
 3 files changed, 80 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm64/boot/dts/ti/k3-am625-sk-mcan-mcu.dtso

diff --git a/arch/arm64/boot/dts/ti/Makefile b/arch/arm64/boot/dts/ti/Makefile
index abe15e76b614..c76be3888e4d 100644
--- a/arch/arm64/boot/dts/ti/Makefile
+++ b/arch/arm64/boot/dts/ti/Makefile
@@ -9,7 +9,7 @@
 # alphabetically.
 
 # Boards with AM62x SoC
-k3-am625-sk-mcan-dtbs := k3-am625-sk.dtb k3-am625-sk-mcan-main.dtbo
+k3-am625-sk-mcan-dtbs := k3-am625-sk.dtb k3-am625-sk-mcan-main.dtbo k3-am625-sk-mcan-mcu.dtbo
 dtb-$(CONFIG_ARCH_K3) += k3-am625-beagleplay.dtb
 dtb-$(CONFIG_ARCH_K3) += k3-am625-sk.dtb
 dtb-$(CONFIG_ARCH_K3) += k3-am625-sk-mcan.dtb
diff --git a/arch/arm64/boot/dts/ti/k3-am62-mcu.dtsi b/arch/arm64/boot/dts/ti/k3-am62-mcu.dtsi
index 076601a41e84..20462f457643 100644
--- a/arch/arm64/boot/dts/ti/k3-am62-mcu.dtsi
+++ b/arch/arm64/boot/dts/ti/k3-am62-mcu.dtsi
@@ -141,4 +141,28 @@
 		/* Tightly coupled to M4F */
 		status = "reserved";
 	};
+
+	mcu_mcan1: can@4e00000 {
+		compatible = "bosch,m_can";
+		reg = <0x00 0x4e00000 0x00 0x8000>,
+			  <0x00 0x4e08000 0x00 0x200>;
+		reg-names = "message_ram", "m_can";
+		power-domains = <&k3_pds 188 TI_SCI_PD_EXCLUSIVE>;
+		clocks = <&k3_clks 188 6>, <&k3_clks 188 1>;
+		clock-names = "hclk", "cclk";
+		bosch,mram-cfg = <0x0 128 64 64 64 64 32 32>;
+		status = "disabled";
+	};
+
+	mcu_mcan2: can@4e10000 {
+		compatible = "bosch,m_can";
+		reg = <0x00 0x4e10000 0x00 0x8000>,
+			  <0x00 0x4e18000 0x00 0x200>;
+		reg-names = "message_ram", "m_can";
+		power-domains = <&k3_pds 189 TI_SCI_PD_EXCLUSIVE>;
+		clocks = <&k3_clks 189 6>, <&k3_clks 189 1>;
+		clock-names = "hclk", "cclk";
+		bosch,mram-cfg = <0x0 128 64 64 64 64 32 32>;
+		status = "disabled";
+	};
 };
diff --git a/arch/arm64/boot/dts/ti/k3-am625-sk-mcan-mcu.dtso b/arch/arm64/boot/dts/ti/k3-am625-sk-mcan-mcu.dtso
new file mode 100644
index 000000000000..7a527fdd4981
--- /dev/null
+++ b/arch/arm64/boot/dts/ti/k3-am625-sk-mcan-mcu.dtso
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0
+/**
+ * DT overlay for MCAN in MCU domain on AM625 SK
+ *
+ * Copyright (C) 2022 Texas Instruments Incorporated - https://www.ti.com/
+ */
+
+/dts-v1/;
+/plugin/;
+
+#include <dt-bindings/pinctrl/k3.h>
+
+&{/} {
+	transceiver2: can-phy1 {
+		compatible = "ti,tcan1042";
+		#phy-cells = <0>;
+		max-bitrate = <5000000>;
+	};
+
+	transceiver3: can-phy2 {
+		compatible = "ti,tcan1042";
+		#phy-cells = <0>;
+		max-bitrate = <5000000>;
+	};
+};
+
+&mcu_pmx0 {
+	mcu_mcan1_pins_default: mcu-mcan1-pins-default {
+		pinctrl-single,pins = <
+			AM62X_IOPAD(0x038, PIN_INPUT, 0) /* (B3) MCU_MCAN0_RX */
+			AM62X_IOPAD(0x034, PIN_OUTPUT, 0) /* (D6) MCU_MCAN0_TX */
+		>;
+	};
+
+	mcu_mcan2_pins_default: mcu-mcan2-pins-default {
+		pinctrl-single,pins = <
+			AM62X_IOPAD(0x040, PIN_INPUT, 0) /* (D4) MCU_MCAN1_RX */
+			AM62X_IOPAD(0x03C, PIN_OUTPUT, 0) /* (E5) MCU_MCAN1_TX */
+		>;
+	};
+};
+
+&mcu_mcan1 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&mcu_mcan1_pins_default>;
+	phys = <&transceiver2>;
+	status = "okay";
+};
+
+&mcu_mcan2 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&mcu_mcan2_pins_default>;
+	phys = <&transceiver3>;
+	status = "okay";
+};
-- 
2.17.1

Re: [PATCH 4/4] DO_NOT_MERGE arm64: dts: ti: Enable MCU MCANs for AM62x

[Francesco Dolcini]

On Wed, Apr 19, 2023 at 05:33:23PM -0500, Judith Mendez wrote:
> On AM62x there are no hardware interrupts routed to GIC interrupt
> controller for MCU MCAN IP, A53 Linux cannot receive hardware
> interrupts. Since an hrtimer will be used to generate software
> interrupts, add MCU MCAN nodes to dtsi and default to disabled.
> 
> AM62x does not carry on-board CAN transceivers, so instead of
> changing DTB permanently use an overlay to enable MCU MCANs and to
> add CAN transceiver nodes.
> 
> If an hrtimer is used to generate software interrupts, the two
> required interrupt attributes in the MCAN node do not have to be
> included.
> 
> Signed-off-by: Judith Mendez <jm@ti.com>

[...]

> +	mcu_mcan1: can@4e00000 {
this should be mcu_mcan0

> +		compatible = "bosch,m_can";
> +		reg = <0x00 0x4e00000 0x00 0x8000>,
> +			  <0x00 0x4e08000 0x00 0x200>;

[...]

> +	mcu_mcan2: can@4e10000 {
mcu_mcan1

> +		compatible = "bosch,m_can";
> +		reg = <0x00 0x4e10000 0x00 0x8000>,
> +			  <0x00 0x4e18000 0x00 0x200>;

Francesco