Re: [PATCH V1 2/2] soc: qcom: aoss: Add debugfs entry

[Bjorn Andersson <bjorn.andersson@linaro.org>]

On Fri 02 Apr 01:17 CDT 2021, 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@codeaurora.org>
> Signed-off-by: Deepak Kumar Singh <deesin@codeaurora.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 5c643f0..1789880 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>
> @@ -86,6 +87,9 @@ 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 {
> @@ -549,6 +553,34 @@ struct qmp *qmp_get(struct device *dev)
>  }
>  EXPORT_SYMBOL(qmp_get);
>  
> +#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 len;

If len >= QMP_MSG_LEN we shouldn't lie to the caller and say that all
went well, better return -EINVAL in this case.

> +
> +	ret  = copy_from_user(buf, userstr, len);
> +	if (ret) {
> +		dev_err(qmp->dev, "copy from user failed, ret:%d\n", ret);
> +		return len;

		return -EFAULT;

And you don't have to print here.

The rest looks good.

Regards,
Bjorn

> +	}
> +
> +	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;
> @@ -603,6 +635,11 @@ static int qmp_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, qmp);
>  
> +#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:
> @@ -619,6 +656,10 @@ 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
>