* [PATCH v5 0/2] Enable multiple MCAN on AM62x @ 2023-05-10 20:29 Judith Mendez 2023-05-10 20:29 ` [PATCH v5 1/2] dt-bindings: net: can: Add poll-interval for MCAN Judith Mendez 2023-05-10 20:29 ` [PATCH v5 2/2] can: m_can: Add hrtimer to generate software interrupt Judith Mendez 0 siblings, 2 replies; 6+ messages in thread From: Judith Mendez @ 2023-05-10 20:29 UTC (permalink / raw) To: linux-can, Chandrasekar Ramakrishnan Cc: Wolfgang Grandegger, Marc Kleine-Budde, David S . Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni, netdev, linux-kernel, Schuyler Patton, devicetree, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Oliver Hartkopp, linux-arm-kernel On AM62x there are two MCANs 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 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. 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. v4: Link: https://lore.kernel.org/linux-can/c3395692-7dbf-19b2-bd3f-31ba86fa4ac9@linaro.org/T/#t v2: Link: https://lore.kernel.org/linux-can/20230424195402.516-1-jm@ti.com/T/#t V1: Link: https://lore.kernel.org/linux-can/19d8ae7f-7b74-a869-a818-93b74d106709@ti.com/T/#t RFC: Link: https://lore.kernel.org/linux-can/52a37e51-4143-9017-42ee-8d17c67028e3@ti.com/T/#t Changes since v4: - Remove poll-interval in bindings - Change dev_dbg to dev_info for case where hardware int exists and polling is enabled Changes since v3: - Wrong patches sent 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 (2): dt-bindings: net: can: Add poll-interval for MCAN can: m_can: Add hrtimer to generate software interrupt .../bindings/net/can/bosch,m_can.yaml | 20 +++++++++-- drivers/net/can/m_can/m_can.c | 28 ++++++++++++++- drivers/net/can/m_can/m_can.h | 4 +++ drivers/net/can/m_can/m_can_platform.c | 35 +++++++++++++++++-- 4 files changed, 81 insertions(+), 6 deletions(-) base-commit: 578215f3e21c472c08d70b8796edf1ac58f88578 -- 2.17.1 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v5 1/2] dt-bindings: net: can: Add poll-interval for MCAN 2023-05-10 20:29 [PATCH v5 0/2] Enable multiple MCAN on AM62x Judith Mendez @ 2023-05-10 20:29 ` Judith Mendez 2023-05-11 9:30 ` Krzysztof Kozlowski 2023-05-10 20:29 ` [PATCH v5 2/2] can: m_can: Add hrtimer to generate software interrupt Judith Mendez 1 sibling, 1 reply; 6+ messages in thread From: Judith Mendez @ 2023-05-10 20:29 UTC (permalink / raw) To: linux-can, Chandrasekar Ramakrishnan Cc: Wolfgang Grandegger, Marc Kleine-Budde, David S . Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni, netdev, linux-kernel, Schuyler Patton, devicetree, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Oliver Hartkopp, linux-arm-kernel On AM62x SoC, MCANs on MCU domain do not have hardware interrupt routed to A53 Linux, instead they will use software interrupt by hrtimer. To enable timer polling method, interrupts should be optional so remove interrupts property from required section and add an example for MCAN node with timer polling enabled. Signed-off-by: Judith Mendez <jm@ti.com> --- .../bindings/net/can/bosch,m_can.yaml | 20 +++++++++++++++++-- 1 file changed, 18 insertions(+), 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..bb518c831f7b 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 @@ -132,6 +130,7 @@ additionalProperties: false examples: - | + // Example with interrupts #include <dt-bindings/clock/imx6sx-clock.h> can@20e8000 { compatible = "bosch,m_can"; @@ -149,4 +148,21 @@ examples: }; }; + - | + // Example with timer polling + #include <dt-bindings/clock/imx6sx-clock.h> + can@20e8000 { + compatible = "bosch,m_can"; + reg = <0x020e8000 0x4000>, <0x02298000 0x4000>; + reg-names = "m_can", "message_ram"; + clocks = <&clks IMX6SX_CLK_CANFD>, + <&clks IMX6SX_CLK_CANFD>; + clock-names = "hclk", "cclk"; + bosch,mram-cfg = <0x0 0 0 32 0 0 0 1>; + + can-transceiver { + max-bitrate = <5000000>; + }; + }; + ... -- 2.17.1 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v5 1/2] dt-bindings: net: can: Add poll-interval for MCAN 2023-05-10 20:29 ` [PATCH v5 1/2] dt-bindings: net: can: Add poll-interval for MCAN Judith Mendez @ 2023-05-11 9:30 ` Krzysztof Kozlowski 0 siblings, 0 replies; 6+ messages in thread From: Krzysztof Kozlowski @ 2023-05-11 9:30 UTC (permalink / raw) To: Judith Mendez, linux-can, Chandrasekar Ramakrishnan Cc: Wolfgang Grandegger, Marc Kleine-Budde, David S . Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni, netdev, linux-kernel, Schuyler Patton, devicetree, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Oliver Hartkopp, linux-arm-kernel On 10/05/2023 22:29, Judith Mendez wrote: > On AM62x SoC, MCANs on MCU domain do not have hardware interrupt > routed to A53 Linux, instead they will use software interrupt by > hrtimer. > > To enable timer polling method, interrupts should be > optional so remove interrupts property from required section and > add an example for MCAN node with timer polling enabled. > > Signed-off-by: Judith Mendez <jm@ti.com> > --- Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> Best regards, Krzysztof ^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v5 2/2] can: m_can: Add hrtimer to generate software interrupt 2023-05-10 20:29 [PATCH v5 0/2] Enable multiple MCAN on AM62x Judith Mendez 2023-05-10 20:29 ` [PATCH v5 1/2] dt-bindings: net: can: Add poll-interval for MCAN Judith Mendez @ 2023-05-10 20:29 ` Judith Mendez 2023-05-11 6:23 ` Tony Lindgren 1 sibling, 1 reply; 6+ messages in thread From: Judith Mendez @ 2023-05-10 20:29 UTC (permalink / raw) To: linux-can, Chandrasekar Ramakrishnan Cc: Wolfgang Grandegger, Marc Kleine-Budde, David S . Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni, netdev, linux-kernel, Schuyler Patton, devicetree, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Oliver Hartkopp, linux-arm-kernel Add an hrtimer to MCAN class device. Each MCAN will have its own hrtimer instantiated if there is no hardware interrupt found and poll-interval property is defined in device tree M_CAN node. 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 | 28 ++++++++++++++++++++- drivers/net/can/m_can/m_can.h | 4 +++ drivers/net/can/m_can/m_can_platform.c | 35 +++++++++++++++++++++++--- 3 files changed, 63 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..85009b803c70 100644 --- a/drivers/net/can/m_can/m_can.c +++ b/drivers/net/can/m_can/m_can.c @@ -11,6 +11,7 @@ #include <linux/bitfield.h> #include <linux/can/dev.h> #include <linux/ethtool.h> +#include <linux/hrtimer.h> #include <linux/interrupt.h> #include <linux/io.h> #include <linux/iopoll.h> @@ -308,6 +309,9 @@ enum m_can_reg { #define TX_EVENT_MM_MASK GENMASK(31, 24) #define TX_EVENT_TXTS_MASK GENMASK(15, 0) +/* Hrtimer polling interval */ +#define HRTIMER_POLL_INTERVAL 1 + /* The ID and DLC registers are adjacent in M_CAN FIFO memory, * and we can save a (potentially slow) bus round trip by combining * reads and writes to them. @@ -1587,6 +1591,11 @@ static int m_can_close(struct net_device *dev) if (!cdev->is_peripheral) napi_disable(&cdev->napi); + if (cdev->polling) { + 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 +1802,18 @@ static netdev_tx_t m_can_start_xmit(struct sk_buff *skb, return NETDEV_TX_OK; } +static 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(HRTIMER_POLL_INTERVAL)); + + return HRTIMER_RESTART; +} + static int m_can_open(struct net_device *dev) { struct m_can_classdev *cdev = netdev_priv(dev); @@ -1831,9 +1852,14 @@ 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 (!cdev->polling) { err = request_irq(dev->irq, m_can_isr, IRQF_SHARED, dev->name, dev); + } else { + dev_dbg(cdev->dev, "Start hrtimer\n"); + cdev->hrtimer.function = &hrtimer_callback; + hrtimer_start(&cdev->hrtimer, ms_to_ktime(HRTIMER_POLL_INTERVAL), + 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..e9db5cce4e68 100644 --- a/drivers/net/can/m_can/m_can.h +++ b/drivers/net/can/m_can/m_can.h @@ -15,6 +15,7 @@ #include <linux/device.h> #include <linux/dma-mapping.h> #include <linux/freezer.h> +#include <linux/hrtimer.h> #include <linux/interrupt.h> #include <linux/io.h> #include <linux/iopoll.h> @@ -93,6 +94,9 @@ struct m_can_classdev { int is_peripheral; struct mram_cfg mcfg[MRAM_CFG_NUM]; + + struct hrtimer hrtimer; + bool polling; }; 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..79ad1a3c0060 100644 --- a/drivers/net/can/m_can/m_can_platform.c +++ b/drivers/net/can/m_can/m_can_platform.c @@ -5,6 +5,7 @@ // // Copyright (C) 2018-19 Texas Instruments Incorporated - http://www.ti.com/ +#include <linux/hrtimer.h> #include <linux/phy/phy.h> #include <linux/platform_device.h> @@ -96,12 +97,40 @@ static int m_can_plat_probe(struct platform_device *pdev) goto probe_fail; addr = devm_platform_ioremap_resource_byname(pdev, "m_can"); - irq = platform_get_irq_byname(pdev, "int0"); - if (IS_ERR(addr) || irq < 0) { - ret = -EINVAL; + if (IS_ERR(addr)) { + ret = PTR_ERR(addr); goto probe_fail; } + irq = platform_get_irq_byname_optional(pdev, "int0"); + if (irq == -EPROBE_DEFER) { + ret = -EPROBE_DEFER; + goto probe_fail; + } + + if (device_property_present(mcan_class->dev, "interrupts") || + device_property_present(mcan_class->dev, "interrupt-names")) + mcan_class->polling = false; + else + mcan_class->polling = true; + + if (!mcan_class->polling && irq < 0) { + ret = -ENXIO; + dev_err_probe(mcan_class->dev, ret, "IRQ int0 not found, polling not activated\n"); + goto probe_fail; + } + + if (mcan_class->polling) { + if (irq > 0) { + mcan_class->polling = false; + dev_info(mcan_class->dev, "Polling enabled, using hardware IRQ\n"); + } else { + dev_dbg(mcan_class->dev, "Polling enabled, initialize hrtimer"); + hrtimer_init(&mcan_class->hrtimer, CLOCK_MONOTONIC, + HRTIMER_MODE_REL_PINNED); + } + } + /* message ram could be shared */ res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "message_ram"); if (!res) { -- 2.17.1 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v5 2/2] can: m_can: Add hrtimer to generate software interrupt 2023-05-10 20:29 ` [PATCH v5 2/2] can: m_can: Add hrtimer to generate software interrupt Judith Mendez @ 2023-05-11 6:23 ` Tony Lindgren 2023-05-12 20:26 ` Judith Mendez 0 siblings, 1 reply; 6+ messages in thread From: Tony Lindgren @ 2023-05-11 6:23 UTC (permalink / raw) To: Judith Mendez Cc: linux-can, Chandrasekar Ramakrishnan, Wolfgang Grandegger, Marc Kleine-Budde, David S . Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni, netdev, linux-kernel, Schuyler Patton, devicetree, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Oliver Hartkopp, linux-arm-kernel Hi, * Judith Mendez <jm@ti.com> [230510 20:31]: > Add an hrtimer to MCAN class device. Each MCAN will have its own > hrtimer instantiated if there is no hardware interrupt found and > poll-interval property is defined in device tree M_CAN node. > > 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. So what about system suspend, do you need to do something to ensure the timer does not happen to run while suspending? Regards, Tony ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v5 2/2] can: m_can: Add hrtimer to generate software interrupt 2023-05-11 6:23 ` Tony Lindgren @ 2023-05-12 20:26 ` Judith Mendez 0 siblings, 0 replies; 6+ messages in thread From: Judith Mendez @ 2023-05-12 20:26 UTC (permalink / raw) To: Tony Lindgren Cc: linux-can, Chandrasekar Ramakrishnan, Wolfgang Grandegger, Marc Kleine-Budde, David S . Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni, netdev, linux-kernel, Schuyler Patton, devicetree, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Oliver Hartkopp, linux-arm-kernel Hello Tony, On 5/11/23 01:23, Tony Lindgren wrote: > Hi, > > * Judith Mendez <jm@ti.com> [230510 20:31]: >> Add an hrtimer to MCAN class device. Each MCAN will have its own >> hrtimer instantiated if there is no hardware interrupt found and >> poll-interval property is defined in device tree M_CAN node. >> >> 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. > > So what about system suspend, do you need to do something to > ensure the timer does not happen to run while suspending? Great question. Tested the MCAN using timer polling method and it seems to suspend to RAM but not resume. Meanwhile MCAN using hardware irq suspends and resumes from RAM just fine. Will look deeper into this here soon. Thank you Tony for bringing this up. regards, Judith ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-05-12 22:30 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2023-05-10 20:29 [PATCH v5 0/2] Enable multiple MCAN on AM62x Judith Mendez 2023-05-10 20:29 ` [PATCH v5 1/2] dt-bindings: net: can: Add poll-interval for MCAN Judith Mendez 2023-05-11 9:30 ` Krzysztof Kozlowski 2023-05-10 20:29 ` [PATCH v5 2/2] can: m_can: Add hrtimer to generate software interrupt Judith Mendez 2023-05-11 6:23 ` Tony Lindgren 2023-05-12 20:26 ` Judith Mendez
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