can: m_can: Add hrtimer to generate software interrupt

Introduce timer polling method to MCAN since some SoCs may not
have M_CAN interrupt routed to A53 Linux and do not have
interrupt property in device tree M_CAN node.

On AM62x SoC, MCANs on MCU domain do not have hardware interrupt
routed to A53 Linux, instead they will use timer polling method.

Add an hrtimer to MCAN class device. Each MCAN will have its own
hrtimer instantiated if there is no hardware interrupt found in
device tree M_CAN node. The timer 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.

Tested-by: Hiago De Franco <hiago.franco@toradex.com> # Toradex Verdin AM62
Reviewed-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Judith Mendez <jm@ti.com>
Link: https://lore.kernel.org/all/20230707204714.62964-3-jm@ti.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index c5af92bcc9c98afdf2eb0d477baead63d03f0987..13fd84b2e2ddecd5ee66b6e1dc0b48d738fb7c76 100644 (file)
--- 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_MS               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.
@@ -1414,6 +1418,12 @@ static int m_can_start(struct net_device *dev)
 
        m_can_enable_all_interrupts(cdev);
 
+       if (!dev->irq) {
+               dev_dbg(cdev->dev, "Start hrtimer\n");
+               hrtimer_start(&cdev->hrtimer, ms_to_ktime(HRTIMER_POLL_INTERVAL_MS),
+                             HRTIMER_MODE_REL_PINNED);
+       }
+
        return 0;
 }
 
@@ -1568,6 +1578,11 @@ static void m_can_stop(struct net_device *dev)
 {
        struct m_can_classdev *cdev = netdev_priv(dev);
 
+       if (!dev->irq) {
+               dev_dbg(cdev->dev, "Stop hrtimer\n");
+               hrtimer_cancel(&cdev->hrtimer);
+       }
+
        /* disable all interrupts */
        m_can_disable_all_interrupts(cdev);
 
@@ -1793,6 +1808,18 @@ 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_MS));
+
+       return HRTIMER_RESTART;
+}
+
 static int m_can_open(struct net_device *dev)
 {
        struct m_can_classdev *cdev = netdev_priv(dev);
@@ -1831,7 +1858,7 @@ 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 (dev->irq) {
                err = request_irq(dev->irq, m_can_isr, IRQF_SHARED, dev->name,
                                  dev);
        }
@@ -2027,6 +2054,9 @@ int m_can_class_register(struct m_can_classdev *cdev)
                        goto clk_disable;
        }
 
+       if (!cdev->net->irq)
+               cdev->hrtimer.function = &hrtimer_callback;
+
        ret = m_can_dev_setup(cdev);
        if (ret)
                goto rx_offload_del;

diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
index a839dc71dc9ba998da4e3a78bd72af2dd503279c..2ac18ac867a454320ee99272f84f71d6d7db267f 100644 (file)
--- 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 +94,8 @@ struct m_can_classdev {
        int is_peripheral;
 
        struct mram_cfg mcfg[MRAM_CFG_NUM];
+
+       struct hrtimer hrtimer;
 };
 
 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 94dc82644113617d7740bf77c06da35037230b03..cdb28d6a092c6d043dd4af65459943abc6bc473c 100644 (file)
--- 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>
 
@@ -82,7 +83,7 @@ static int m_can_plat_probe(struct platform_device *pdev)
        void __iomem *addr;
        void __iomem *mram_addr;
        struct phy *transceiver;
-       int irq, ret = 0;
+       int irq = 0, ret = 0;
 
        mcan_class = m_can_class_allocate_dev(&pdev->dev,
                                              sizeof(struct m_can_plat_priv));
@@ -96,12 +97,24 @@ 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;
        }
 
+       if (device_property_present(mcan_class->dev, "interrupts") ||
+           device_property_present(mcan_class->dev, "interrupt-names")) {
+               irq = platform_get_irq_byname(pdev, "int0");
+               if (irq < 0) {
+                       ret = irq;
+                       goto probe_fail;
+               }
+       } 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) {