[v5,2/2] can: m_can: Add hrtimer to generate software interrupt
Commit Message
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(-)
Comments
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
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
@@ -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) {
@@ -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);
@@ -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) {