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:
v6:
- Move hrtimer stop/start function calls to m_can_open and m_can_close to
support power suspend/resume
v5:
- Change dev_dbg to dev_info if hardware interrupt exists and polling
is enabled
v4:
- No changes
v3:
- Create a define for 1 ms polling interval
- Change plarform_get_irq to optional to not print error msg
v2:
- Add functionality to check for 'poll-interval' property in MCAN node 
- Add 'polling' flag in driver to check if device is using polling method
- Check for timer polling and hardware interrupt cases, default to
hardware interrupt method
- Change ns_to_ktime() to ms_to_ktime()
---
 drivers/net/can/m_can/m_can.c          | 31 ++++++++++++++++++++++-
 drivers/net/can/m_can/m_can.h          |  4 +++
 drivers/net/can/m_can/m_can_platform.c | 35 +++++++++++++++++++++++---
 3 files changed, 66 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..cfb3e433c0dd 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.
@@ -1414,6 +1418,12 @@ static int m_can_start(struct net_device *dev)
 
 	m_can_enable_all_interrupts(cdev);
 
+	if (cdev->polling) {
+		dev_dbg(cdev->dev, "Start hrtimer\n");
+		hrtimer_start(&cdev->hrtimer, ms_to_ktime(HRTIMER_POLL_INTERVAL),
+			      HRTIMER_MODE_REL_PINNED);
+	}
+
 	return 0;
 }
 
@@ -1571,6 +1581,11 @@ static void m_can_stop(struct net_device *dev)
 	/* disable all interrupts */
 	m_can_disable_all_interrupts(cdev);
 
+	if (cdev->polling) {
+		dev_dbg(cdev->dev, "Disabling the hrtimer\n");
+		hrtimer_cancel(&cdev->hrtimer);
+	}
+
 	/* Set init mode to disengage from the network */
 	m_can_config_endisable(cdev, true);
 
@@ -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));
+
+	return HRTIMER_RESTART;
+}
+
 static int m_can_open(struct net_device *dev)
 {
 	struct m_can_classdev *cdev = netdev_priv(dev);
@@ -1831,9 +1858,11 @@ 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 {
+		cdev->hrtimer.function = &hrtimer_callback;
 	}
 
 	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 94dc82644113..3e60cebd9d12 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

On 18.05.2023 14:36:13, Judith Mendez wrote:
> 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>

[...]

> diff --git a/drivers/net/can/m_can/m_can_platform.c b/drivers/net/can/m_can/m_can_platform.c
> index 94dc82644113..3e60cebd9d12 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;
>  	}
>  

As we don't use an explicit "poll-interval" anymore, this needs some
cleanup. The flow should be (pseudo code, error handling omitted):

if (device_property_present("interrupts") {
        platform_get_irq_byname();
        polling = false;
} else {
        hrtimer_init();
        polling = true;
}

> +	irq = platform_get_irq_byname_optional(pdev, "int0");

Remove the "_optional" and....

> +	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;

...move the platform_get_irq_byname() here

> +	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;
> +	}

Remove this check.

> +
> +	if (mcan_class->polling) {
> +		if (irq > 0) {
> +			mcan_class->polling = false;
> +			dev_info(mcan_class->dev, "Polling enabled, using hardware IRQ\n");

Remove this.

> +		} else {
> +			dev_dbg(mcan_class->dev, "Polling enabled, initialize hrtimer");
> +			hrtimer_init(&mcan_class->hrtimer, CLOCK_MONOTONIC,
> +				     HRTIMER_MODE_REL_PINNED);

move this backwards, where you set "polling = true"

> +		}
> +	}
> +
>  	/* message ram could be shared */
>  	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "message_ram");
>  	if (!res) {
> -- 
> 2.17.1

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |

Hello Marc,

On 5/19/23 2:16 AM, Marc Kleine-Budde wrote:
> On 18.05.2023 14:36:13, Judith Mendez wrote:
>> 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>
> 
> [...]

Missed this poll-interval, thanks.

> 
>> diff --git a/drivers/net/can/m_can/m_can_platform.c b/drivers/net/can/m_can/m_can_platform.c
>> index 94dc82644113..3e60cebd9d12 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;
>>   	}
>>   
> 
> As we don't use an explicit "poll-interval" anymore, this needs some
> cleanup. The flow should be (pseudo code, error handling omitted):
> 
> if (device_property_present("interrupts") {
>          platform_get_irq_byname();
>          polling = false;
> } else {
>          hrtimer_init();
>          polling = true;
> }

Ok.

> 
>> +	irq = platform_get_irq_byname_optional(pdev, "int0");
> 
> Remove the "_optional" and....

On V2, you asked to add the _optional?.....

 >  	irq = platform_get_irq_byname(pdev, "int0");

use platform_get_irq_byname_optional(), it doesn't print an error
message.

> 
>> +	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;
> 
> ...move the platform_get_irq_byname() here

ok,

> 
>> +	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;
>> +	}
> 
> Remove this check.

Should we not go to 'probe fail' if polling is not activated and irq is 
not found?

> 
>> +
>> +	if (mcan_class->polling) {
>> +		if (irq > 0) {
>> +			mcan_class->polling = false;
>> +			dev_info(mcan_class->dev, "Polling enabled, using hardware IRQ\n");
> 
> Remove this.

Remove the dev_info?

> 
>> +		} else {
>> +			dev_dbg(mcan_class->dev, "Polling enabled, initialize hrtimer");
>> +			hrtimer_init(&mcan_class->hrtimer, CLOCK_MONOTONIC,
>> +				     HRTIMER_MODE_REL_PINNED);
> 
> move this backwards, where you set "polling = true"

ok,
> 
>> +		}
>> +	}
>> +
>>   	/* message ram could be shared */
>>   	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "message_ram");
>>   	if (!res) {
>> -- 
>> 2.17.1

- judith

On 22.05.2023 10:17:38, Judith Mendez wrote:
> > > diff --git a/drivers/net/can/m_can/m_can_platform.c b/drivers/net/can/m_can/m_can_platform.c
> > > index 94dc82644113..3e60cebd9d12 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;
> > >   	}
> > 
> > As we don't use an explicit "poll-interval" anymore, this needs some
> > cleanup. The flow should be (pseudo code, error handling omitted):
> > 
> > if (device_property_present("interrupts") {
> >          platform_get_irq_byname();
> >          polling = false;
> > } else {
> >          hrtimer_init();
> >          polling = true;
> > }
> 
> Ok.
> 
> > 
> > > +	irq = platform_get_irq_byname_optional(pdev, "int0");
> > 
> > Remove the "_optional" and....
> 
> On V2, you asked to add the _optional?.....
> 
> >  	irq = platform_get_irq_byname(pdev, "int0");
> 
> use platform_get_irq_byname_optional(), it doesn't print an error
> message.

ACK - I said that back in v2, when there was "poll-interval". But now we
don't use "poll-interval" anymore, but test if interrupt properties are
present.

See again pseudo-code I posted in my last mail:

| if (device_property_present("interrupts") {
|          platform_get_irq_byname();

If this throws an error, it's fatal, bail out.

|          polling = false;
| } else {
|          hrtimer_init();
|          polling = true;
| }


> 
> > 
> > > +	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;
> > 
> > ...move the platform_get_irq_byname() here
> 
> ok,
> 
> > 
> > > +	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;
> > > +	}
> > 
> > Remove this check.
> 
> Should we not go to 'probe fail' if polling is not activated and irq is not
> found?

If an interrupt property is present in the DT, we use it - if request
IRQ fails, something is broken and we've already bailed out. See above.
If there is no interrupt property we use polling.

> 
> > 
> > > +
> > > +	if (mcan_class->polling) {
> > > +		if (irq > 0) {
> > > +			mcan_class->polling = false;
> > > +			dev_info(mcan_class->dev, "Polling enabled, using hardware IRQ\n");
> > 
> > Remove this.
> 
> Remove the dev_info?

ACK, this is not possible anymore - we cannot have polling enabled and
HW IRQs configured.

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |

Hello,

On 5/22/23 1:37 PM, Marc Kleine-Budde wrote:
> On 22.05.2023 10:17:38, Judith Mendez wrote:
>>>> diff --git a/drivers/net/can/m_can/m_can_platform.c b/drivers/net/can/m_can/m_can_platform.c
>>>> index 94dc82644113..3e60cebd9d12 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;
>>>>    	}
>>>
>>> As we don't use an explicit "poll-interval" anymore, this needs some
>>> cleanup. The flow should be (pseudo code, error handling omitted):
>>>
>>> if (device_property_present("interrupts") {
>>>           platform_get_irq_byname();
>>>           polling = false;
>>> } else {
>>>           hrtimer_init();
>>>           polling = true;
>>> }
>>
>> Ok.
>>
>>>
>>>> +	irq = platform_get_irq_byname_optional(pdev, "int0");
>>>
>>> Remove the "_optional" and....
>>
>> On V2, you asked to add the _optional?.....
>>
>>>   	irq = platform_get_irq_byname(pdev, "int0");
>>
>> use platform_get_irq_byname_optional(), it doesn't print an error
>> message.
> 
> ACK - I said that back in v2, when there was "poll-interval". But now we
> don't use "poll-interval" anymore, but test if interrupt properties are
> present.
> 
> See again pseudo-code I posted in my last mail:
> 
> | if (device_property_present("interrupts") {
> |          platform_get_irq_byname();
> 
> If this throws an error, it's fatal, bail out.
> 
> |          polling = false;
> | } else {
> |          hrtimer_init();
> |          polling = true;
> | }
> 

Ok, will add this then..


>>
>>>
>>>> +	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;
>>>
>>> ...move the platform_get_irq_byname() here
>>
>> ok,
>>
>>>
>>>> +	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;
>>>> +	}
>>>
>>> Remove this check.
>>
>> Should we not go to 'probe fail' if polling is not activated and irq is not
>> found?
> 
> If an interrupt property is present in the DT, we use it - if request
> IRQ fails, something is broken and we've already bailed out. See above.
> If there is no interrupt property we use polling.

Got it, thanks.

>>
>>>
>>>> +
>>>> +	if (mcan_class->polling) {
>>>> +		if (irq > 0) {
>>>> +			mcan_class->polling = false;
>>>> +			dev_info(mcan_class->dev, "Polling enabled, using hardware IRQ\n");
>>>
>>> Remove this.
>>
>> Remove the dev_info?
> 
> ACK, this is not possible anymore - we cannot have polling enabled and
> HW IRQs configured.

Sounds good, will submit a v7 with these cleanup changes.

regards,
Judith