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Subject[PATCH v4 2/4] can: m_can: Add hrtimer to generate software interrupt
Date
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>
---
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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