Re: [PATCH v2 1/4] can: m_can: Add hrtimer to generate software interrupt

[Simon Horman]

On Mon, Apr 24, 2023 at 02:53:59PM -0500, 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@xxxxxx>
> ---
> Changelog:
> 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. Changed ms_to_ktime() to ns_to_ktime()
> 	5. Removed newlines, tabs, and restructure if/else section.
> 
>  drivers/net/can/m_can/m_can.c          | 30 ++++++++++++++++++++-----
>  drivers/net/can/m_can/m_can.h          |  5 +++++
>  drivers/net/can/m_can/m_can_platform.c | 31 ++++++++++++++++++++++++--
>  3 files changed, 59 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index a5003435802b..33e094f88da1 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -23,6 +23,7 @@
>  #include <linux/pinctrl/consumer.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/hrtimer.h>
>  
>  #include "m_can.h"
>  
> @@ -1587,6 +1588,11 @@ 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 +1799,18 @@ static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
>  	return NETDEV_TX_OK;
>  }
>  
> +enum hrtimer_restart hrtimer_callback(struct hrtimer *timer)

Hi Judith,

This function seems to only be used in this file,
so it should be static.

> +{
> +	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(1));
> +
> +	return HRTIMER_RESTART;
> +}
> +

...