[PATCH v4 2/4] can: m_can: Add hrtimer to generate software interrupt
Judith Mendez
jm at ti.com
Mon May 1 15:46:22 PDT 2023
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 at ti.com>
---
Changelog:
v1:
1. Sort list of includes
2. Create a define for HR_TIMER_POLL_INTERVAL
3. Fix indentations and style issues/warnings
4. Change polling variable to type bool
5. Change platform_get_irq to optional so not to print error msg
6. Move error check for addr directly after assignment
7. Print appropriate error msg with dev_err_probe insead of dev_dbg
v2:
1. Add poll-interval to MCAN class device to check if poll-interval propery is
present in MCAN node, this enables timer polling method
2. Add 'polling' flag to MCAN class device to check if a device is using timer
polling method
3. Check if both timer polling and hardware interrupt are enabled for a MCAN
device, default to hardware interrupt mode if both are enabled
4. Change ms_to_ktime() to ns_to_ktime()
5. Remove newlines, tabs, and restructure if/else section
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 +++++++++++++++++++++++---
3 files changed, 60 insertions(+), 5 deletions(-)
diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index a5003435802b..e1ac0c1d85a3 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);
@@ -1827,13 +1848,17 @@ 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 {
+ } 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..0fcb436298f8 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 +97,37 @@ 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, "poll-interval"))
+ mcan_class->polling = 1;
+
+ if (!mcan_class->polling && irq < 0) {
+ ret = -ENXIO;
+ dev_err_probe(mcan_class->dev, ret, "IRQ int0 not found and polling not activated\n");
+ goto probe_fail;
+ }
+
+ if (mcan_class->polling) {
+ if (irq > 0) {
+ mcan_class->polling = 0;
+ dev_dbg(mcan_class->dev, "Polling enabled and hardware IRQ found, use 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
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