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 MCAN device when there is no hardware interrupt and there is
poll-interval property in DTB MCAN node. The 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.
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':
Link: https://lore.kernel.org/lkml/[email protected]/T/
v2:
Link: https://lore.kernel.org/linux-can/[email protected]/T/#t
V1:
Link: https://lore.kernel.org/linux-can/[email protected]/T/#t
RFC:
Link: https://lore.kernel.org/linux-can/[email protected]/T/#t
Changes since v3:
- Wrong patch sent, resend correct patch series
Changes since v2:
- Change binding patch first
- Update binding poll-interval description
- Add oneOf to select either interrupts/interrupt-names or poll-interval
- Sort list of includes
- Create a define for 1 ms polling interval
- Change plarform_get_irq to optional to not print error msg
- Fix indentations, lengths of code lines, and added other style changes
Changes since v1:
- Add poll-interval property to bindings and MCAN DTB node
- Add functionality to check for 'poll-interval' property in MCAN node
- Bindings: add an example using poll-interval
- Add 'polling' flag in driver to check if device is using polling method
- Check for both timer polling and hardware interrupt case, default to
hardware interrupt method
- Change ns_to_ktime() to ms_to_ktime()
Judith Mendez (4):
dt-bindings: net: can: Add poll-interval for MCAN
can: m_can: Add hrtimer to generate software interrupt
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 | 36 +++++++++++-
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 | 57 +++++++++++++++++++
drivers/net/can/m_can/m_can.c | 29 +++++++++-
drivers/net/can/m_can/m_can.h | 4 ++
drivers/net/can/m_can/m_can_platform.c | 32 ++++++++++-
8 files changed, 212 insertions(+), 7 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
base-commit: 92e815cf07ed24ee1c51b122f24ffcf2964b4b13
--
2.17.1
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.
This DT overlay can be used with the following EVM:
Link: https://www.ti.com/tool/TCAN1042DEVM
Signed-off-by: Judith Mendez <[email protected]>
---
Changelog:
v3:
1. Add link for specific board
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..0a7b2f394f87
--- /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 "k3-pinctrl.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
On AM62x there are no hardware interrupts routed to A53 GIC
interrupt controller for MCU MCAN IPs, so MCU MCANs were not
added to the MCU dtsi. In this patch series an hrtimer is introduced
to MCAN driver to generate software interrupts. Now add MCU MCAN
nodes to the MCU dtsi but disable the MCAN devices by default.
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 there is no hardware interrupt and timer method is used, remove
interrupt properties and add poll-interval to enable the hrtimer
per MCAN node.
This DT overlay can be used with the following EVM:
Link: https://www.ti.com/tool/TCAN1042DEVM
Signed-off-by: Judith Mendez <[email protected]>
---
Changelog:
v3:
1. Add link for specific board
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 | 57 +++++++++++++++++++
3 files changed, 82 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..5145b3de4f9b
--- /dev/null
+++ b/arch/arm64/boot/dts/ti/k3-am625-sk-mcan-mcu.dtso
@@ -0,0 +1,57 @@
+// 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 "k3-pinctrl.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 {
+ poll-interval;
+ pinctrl-names = "default";
+ pinctrl-0 = <&mcu_mcan1_pins_default>;
+ phys = <&transceiver2>;
+ status = "okay";
+};
+
+&mcu_mcan2 {
+ poll-interval;
+ pinctrl-names = "default";
+ pinctrl-0 = <&mcu_mcan2_pins_default>;
+ phys = <&transceiver3>;
+ status = "okay";
+};
--
2.17.1
On 17:46-20230501, Judith Mendez wrote:
> 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.
>
> This DT overlay can be used with the following EVM:
> Link: https://www.ti.com/tool/TCAN1042DEVM
>
> Signed-off-by: Judith Mendez <[email protected]>
> ---
> Changelog:
> v3:
> 1. Add link for specific board
>
> 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
NAK.
https://lore.kernel.org/all/[email protected]/
Same reasons - we don't want specific instance based overlays please -
that would'nt make sense - maxbitrate will depend on transceiver so it
has nothing to do with mcan-main or mcan-mcu and has everything to do
with the board that is plugged in.
> 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..0a7b2f394f87
> --- /dev/null
> +++ b/arch/arm64/boot/dts/ti/k3-am625-sk-mcan-main.dtso
If you are going down this road: am625-sk-tcan10242d.dsto (enable main
and mcu?) or something reasonable. Though looking at the pins, I fail
to see how this physically plugs into AM625-SK (I am hoping the answer
isn't breadboard or jumper wires..).
> @@ -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 "k3-pinctrl.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
>
--
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3 1A34 DDB5 849D 1736 249D
On 02/05/2023 00:46, Judith Mendez wrote:
> 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 MCAN device when there is no hardware interrupt and there is
> poll-interval property in DTB MCAN node. The 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.
>
> 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':
> Link: https://lore.kernel.org/lkml/[email protected]/T/
>
> v2:
> Link: https://lore.kernel.org/linux-can/[email protected]/T/#t
>
> V1:
> Link: https://lore.kernel.org/linux-can/[email protected]/T/#t
>
> RFC:
> Link: https://lore.kernel.org/linux-can/[email protected]/T/#t
>
> Changes since v3:
> - Wrong patch sent, resend correct patch series
Sending patchsets every 10 minutes does not help us...
Best regards,
Krzysztof