linux-kernel - Re: [PATCH v4 1/3] bus: mhi: host: Add sysfs entry to force device to enter EDL

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Message-ID: <20240425135300.GE3449@thinkpad>
Date: Thu, 25 Apr 2024 19:23:00 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: Qiang Yu <quic_qianyu@...cinc.com>
Cc: mani@...nel.org, quic_jhugo@...cinc.com, mhi@...ts.linux.dev,
	linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
	quic_cang@...cinc.com, quic_mrana@...cinc.com
Subject: Re: [PATCH v4 1/3] bus: mhi: host: Add sysfs entry to force device
 to enter EDL

On Tue, Apr 23, 2024 at 06:33:35PM +0800, Qiang Yu wrote:
> Add sysfs entry to allow users of MHI bus force device to enter EDL.
> Considering that the way to enter EDL mode varies from device to device and
> some devices even do not support EDL. Hence, add a callback edl_trigger in
> mhi controller as part of the sysfs entry to be invoked and MHI core will
> only create EDL sysfs entry for mhi controller that provides edl_trigger
> callback. All of the process a specific device required to enter EDL mode
> can be placed in this callback.
> 
> Signed-off-by: Qiang Yu <quic_qianyu@...cinc.com>

One nitpick below. But I'll fix it while applying.

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>

> ---
>  Documentation/ABI/stable/sysfs-bus-mhi | 13 +++++++++++++
>  drivers/bus/mhi/host/init.c            | 33 +++++++++++++++++++++++++++++++++
>  include/linux/mhi.h                    |  2 ++
>  3 files changed, 48 insertions(+)
> 
> diff --git a/Documentation/ABI/stable/sysfs-bus-mhi b/Documentation/ABI/stable/sysfs-bus-mhi
> index 1a47f9e..b44f467 100644
> --- a/Documentation/ABI/stable/sysfs-bus-mhi
> +++ b/Documentation/ABI/stable/sysfs-bus-mhi
> @@ -29,3 +29,16 @@ Description:	Initiates a SoC reset on the MHI controller.  A SoC reset is
>                  This can be useful as a method of recovery if the device is
>                  non-responsive, or as a means of loading new firmware as a
>                  system administration task.
> +
> +What:           /sys/bus/mhi/devices/.../trigger_edl
> +Date:           April 2024
> +KernelVersion:  6.9

6.9 is done, now we are working for 6.10 (feature wise).

- Mani

> +Contact:        mhi@...ts.linux.dev
> +Description:    Writing a non-zero value to this file will force devices to
> +                enter EDL (Emergency Download) mode. This entry only exists for
> +                devices capable of entering the EDL mode using the standard EDL
> +                triggering mechanism defined in the MHI spec v1.2. Once in EDL
> +                mode, the flash programmer image can be downloaded to the
> +                device to enter the flash programmer execution environment.
> +                This can be useful if user wants to use QDL (Qualcomm Download,
> +                which is used to download firmware over EDL) to update firmware.
> diff --git a/drivers/bus/mhi/host/init.c b/drivers/bus/mhi/host/init.c
> index 44f9349..7104c18 100644
> --- a/drivers/bus/mhi/host/init.c
> +++ b/drivers/bus/mhi/host/init.c
> @@ -127,6 +127,30 @@ static ssize_t soc_reset_store(struct device *dev,
>  }
>  static DEVICE_ATTR_WO(soc_reset);
>  
> +static ssize_t trigger_edl_store(struct device *dev,
> +			       struct device_attribute *attr,
> +			       const char *buf, size_t count)
> +{
> +	struct mhi_device *mhi_dev = to_mhi_device(dev);
> +	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
> +	unsigned long val;
> +	int ret;
> +
> +	ret = kstrtoul(buf, 10, &val);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (!val)
> +		return -EINVAL;
> +
> +	ret = mhi_cntrl->edl_trigger(mhi_cntrl);
> +	if (ret)
> +		return ret;
> +
> +	return count;
> +}
> +static DEVICE_ATTR_WO(trigger_edl);
> +
>  static struct attribute *mhi_dev_attrs[] = {
>  	&dev_attr_serial_number.attr,
>  	&dev_attr_oem_pk_hash.attr,
> @@ -1018,6 +1042,12 @@ int mhi_register_controller(struct mhi_controller *mhi_cntrl,
>  	if (ret)
>  		goto err_release_dev;
>  
> +	if (mhi_cntrl->edl_trigger) {
> +		ret = sysfs_create_file(&mhi_dev->dev.kobj, &dev_attr_trigger_edl.attr);
> +		if (ret)
> +			goto err_release_dev;
> +	}
> +
>  	mhi_cntrl->mhi_dev = mhi_dev;
>  
>  	mhi_create_debugfs(mhi_cntrl);
> @@ -1051,6 +1081,9 @@ void mhi_unregister_controller(struct mhi_controller *mhi_cntrl)
>  	mhi_deinit_free_irq(mhi_cntrl);
>  	mhi_destroy_debugfs(mhi_cntrl);
>  
> +	if (mhi_cntrl->edl_trigger)
> +		sysfs_remove_file(&mhi_dev->dev.kobj, &dev_attr_trigger_edl.attr);
> +
>  	destroy_workqueue(mhi_cntrl->hiprio_wq);
>  	kfree(mhi_cntrl->mhi_cmd);
>  	kfree(mhi_cntrl->mhi_event);
> diff --git a/include/linux/mhi.h b/include/linux/mhi.h
> index cde01e1..d968e1a 100644
> --- a/include/linux/mhi.h
> +++ b/include/linux/mhi.h
> @@ -353,6 +353,7 @@ struct mhi_controller_config {
>   * @read_reg: Read a MHI register via the physical link (required)
>   * @write_reg: Write a MHI register via the physical link (required)
>   * @reset: Controller specific reset function (optional)
> + * @edl_trigger: CB function to trigger EDL mode (optional)
>   * @buffer_len: Bounce buffer length
>   * @index: Index of the MHI controller instance
>   * @bounce_buf: Use of bounce buffer
> @@ -435,6 +436,7 @@ struct mhi_controller {
>  	void (*write_reg)(struct mhi_controller *mhi_cntrl, void __iomem *addr,
>  			  u32 val);
>  	void (*reset)(struct mhi_controller *mhi_cntrl);
> +	int (*edl_trigger)(struct mhi_controller *mhi_cntrl);
>  
>  	size_t buffer_len;
>  	int index;
> -- 
> 2.7.4
> 
> 

-- 
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