linux-kernel - Re: [PATCH V2 2/2] soc: qcom: aoss: Add debugfs entry

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Date:   Fri, 9 Apr 2021 13:39:52 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Deepak Kumar Singh <deesin@....qualcomm.com>
Cc:     bjorn.andersson@...aro.org, clew@...eaurora.org,
        sibis@...eaurora.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        Deepak Kumar Singh <deesin@...eaurora.org>,
        Andy Gross <agross@...nel.org>
Subject: Re: [PATCH V2 2/2] soc: qcom: aoss: Add debugfs entry

On Fri, Apr 09, 2021 at 10:09:48AM +0530, Deepak Kumar Singh wrote:
> It can be useful to control the different power states of various
> parts of hardware for device testing. Add a debugfs node for qmp so
> messages can be sent to aoss for debugging and testing purposes.
> 
> Signed-off-by: Chris Lew <clew@...eaurora.org>
> Signed-off-by: Deepak Kumar Singh <deesin@...eaurora.org>
> ---
>  drivers/soc/qcom/qcom_aoss.c | 41 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 41 insertions(+)
> 
> diff --git a/drivers/soc/qcom/qcom_aoss.c b/drivers/soc/qcom/qcom_aoss.c
> index 0e397a7..6057bbe 100644
> --- a/drivers/soc/qcom/qcom_aoss.c
> +++ b/drivers/soc/qcom/qcom_aoss.c
> @@ -4,6 +4,7 @@
>   */
>  #include <dt-bindings/power/qcom-aoss-qmp.h>
>  #include <linux/clk-provider.h>
> +#include <linux/debugfs.h>
>  #include <linux/interrupt.h>
>  #include <linux/io.h>
>  #include <linux/mailbox_client.h>
> @@ -88,6 +89,9 @@ struct qmp {
>  	struct clk_hw qdss_clk;
>  	struct genpd_onecell_data pd_data;
>  	struct qmp_cooling_device *cooling_devs;
> +#if IS_ENABLED(CONFIG_DEBUG_FS)
> +	struct dentry *debugfs_file;
> +#endif /* CONFIG_DEBUG_FS */
>  };
>  
>  struct qmp_pd {
> @@ -560,6 +564,34 @@ void qmp_put(struct platform_device *pdev)
>  }
>  EXPORT_SYMBOL(qmp_put);
>  
> +#if IS_ENABLED(CONFIG_DEBUG_FS)
> +static ssize_t aoss_dbg_write(struct file *file, const char __user *userstr,
> +			      size_t len, loff_t *pos)
> +{
> +	struct qmp *qmp = file->private_data;
> +	char buf[QMP_MSG_LEN] = {};
> +	int ret;
> +
> +	if (!len || len >= QMP_MSG_LEN)
> +		return -EINVAL;
> +
> +	ret  = copy_from_user(buf, userstr, len);
> +	if (ret) {
> +		dev_err(qmp->dev, "copy from user failed, ret:%d\n", ret);

Does the userspace need to know how many bytes were not copied? I don't
think this is a useful information. So you could remove this err print.

With that,

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

Thanks,
Mani

> +		return -EFAULT;
> +	}
> +
> +	ret = qmp_send(qmp, buf, QMP_MSG_LEN);
> +
> +	return ret ? ret : len;
> +}
> +
> +static const struct file_operations aoss_dbg_fops = {
> +	.open = simple_open,
> +	.write = aoss_dbg_write,
> +};
> +#endif /* CONFIG_DEBUG_FS */
> +
>  static int qmp_probe(struct platform_device *pdev)
>  {
>  	struct resource *res;
> @@ -616,6 +648,11 @@ static int qmp_probe(struct platform_device *pdev)
>  
>  	atomic_set(&qmp->orphan, 0);
>  
> +#if IS_ENABLED(CONFIG_DEBUG_FS)
> +	qmp->debugfs_file = debugfs_create_file("aoss_send_message", 0220, NULL,
> +						qmp, &aoss_dbg_fops);
> +#endif /* CONFIG_DEBUG_FS */
> +
>  	return 0;
>  
>  err_remove_qdss_clk:
> @@ -632,6 +669,10 @@ static int qmp_remove(struct platform_device *pdev)
>  {
>  	struct qmp *qmp = platform_get_drvdata(pdev);
>  
> +#if IS_ENABLED(CONFIG_DEBUG_FS)
> +	debugfs_remove(qmp->debugfs_file);
> +#endif /* CONFIG_DEBUG_FS */
> +
>  	qmp_qdss_clk_remove(qmp);
>  	qmp_pd_remove(qmp);
>  	qmp_cooling_devices_remove(qmp);
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>