Re: [RFC PATCH v1 14/14] usb:cdns3: Feature for changing role

[Roger Quadros <rogerq@ti.com>]

On 03/11/18 19:51, Pawel Laszczak wrote:
> Patch adds feature that allow to change role from user space.
> 
> Signed-off-by: Pawel Laszczak <pawell@cadence.com>
> ---
>  drivers/usb/cdns3/Makefile  |  2 +-
>  drivers/usb/cdns3/core.c    |  2 +
>  drivers/usb/cdns3/debugfs.c | 94 +++++++++++++++++++++++++++++++++++++
>  drivers/usb/cdns3/drd.h     |  3 ++
>  4 files changed, 100 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/usb/cdns3/debugfs.c
> 
> diff --git a/drivers/usb/cdns3/Makefile b/drivers/usb/cdns3/Makefile
> index 34e60d03c4ec..08e6cdbebd46 100644
> --- a/drivers/usb/cdns3/Makefile
> +++ b/drivers/usb/cdns3/Makefile
> @@ -1,7 +1,7 @@
>  obj-$(CONFIG_USB_CDNS3)			+= cdns3.o
>  obj-$(CONFIG_USB_CDNS3_PCI_WRAP)	+= cdns3-pci.o
>  
> -cdns3-y					:= core.o drd.o
> +cdns3-y					:= core.o drd.o debugfs.o
>  cdns3-$(CONFIG_USB_CDNS3_GADGET)	+= gadget.o ep0.o debug.o
>  cdns3-$(CONFIG_USB_CDNS3_HOST)		+= host.o
>  cdns3-pci-y		 		:= cdns3-pci-wrap.o
> diff --git a/drivers/usb/cdns3/core.c b/drivers/usb/cdns3/core.c
> index 20ae9e76940e..4012f1007da9 100644
> --- a/drivers/usb/cdns3/core.c
> +++ b/drivers/usb/cdns3/core.c
> @@ -309,6 +309,7 @@ static int cdns3_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto err4;
>  
> +	cdns3_debugfs_init(cdns);
>  	device_set_wakeup_capable(dev, true);
>  	pm_runtime_set_active(dev);
>  	pm_runtime_enable(dev);
> @@ -346,6 +347,7 @@ static int cdns3_remove(struct platform_device *pdev)
>  	pm_runtime_get_sync(&pdev->dev);
>  	pm_runtime_disable(&pdev->dev);
>  	pm_runtime_put_noidle(&pdev->dev);
> +	cdns3_debugfs_exit(cdns);
>  	cdns3_remove_roles(cdns);
>  	usb_phy_shutdown(cdns->usbphy);
>  
> diff --git a/drivers/usb/cdns3/debugfs.c b/drivers/usb/cdns3/debugfs.c
> new file mode 100644
> index 000000000000..d4871bc1a69d
> --- /dev/null
> +++ b/drivers/usb/cdns3/debugfs.c
> @@ -0,0 +1,94 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Cadence USBSS DRD Controller DebugFS filer.
> + *
> + * Copyright (C) 2018 Cadence.
> + *
> + * Author: Pawel Laszczak <pawell@cadence.com>
> + */
> +
> +#include <linux/types.h>
> +#include <linux/debugfs.h>
> +#include <linux/seq_file.h>
> +#include <linux/uaccess.h>
> +
> +#include "core.h"
> +#include "gadget.h"
> +
> +static int cdns3_mode_show(struct seq_file *s, void *unused)
> +{
> +	struct cdns3		*cdns = s->private;
> +
> +	switch (cdns->role) {
> +	case CDNS3_ROLE_HOST:
> +		seq_puts(s, "host\n");
> +		break;
> +	case CDNS3_ROLE_GADGET:
> +		seq_puts(s, "device\n");
> +		break;
> +	case CDNS3_ROLE_OTG:
> +	case CDNS3_ROLE_END:
> +		seq_puts(s, "otg\n");
> +		break;
> +	default:
> +		seq_puts(s, "UNKNOWN mode\n");
> +	}
> +
> +	return 0;
> +}
> +
> +static int cdns3_mode_open(struct inode *inode, struct file *file)
> +{
> +	return single_open(file, cdns3_mode_show, inode->i_private);
> +}
> +
> +static ssize_t cdns3_mode_write(struct file *file,
> +				const char __user *ubuf,
> +				size_t count, loff_t *ppos)
> +{
> +	struct seq_file		*s = file->private_data;
> +	struct cdns3		*cdns = s->private;
> +	u32			mode = 0;
> +	char			buf[32];
> +
> +	if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
> +		return -EFAULT;
> +
> +	if (!strncmp(buf, "host", 4))
> +		mode = USB_DR_MODE_HOST;
> +
> +	if (!strncmp(buf, "device", 6))
> +		mode = USB_DR_MODE_PERIPHERAL;
> +
> +	if (!strncmp(buf, "otg", 3))
> +		mode = USB_DR_MODE_OTG;
> +
> +	cdns->desired_role = mode;
> +	queue_work(system_freezable_wq, &cdns->role_switch_wq);

If we start with OTG mode and user says change mode to device will we still
switch to host based on ID pin change?

If it does then this isn't working correctly.
We need to stop processing ID interrupts and keep the role static till
the user switches it back to otg.

> +	return count;
> +}
> +
> +static const struct file_operations cdns3_mode_fops = {
> +	.open			= cdns3_mode_open,
> +	.write			= cdns3_mode_write,
> +	.read			= seq_read,
> +	.llseek			= seq_lseek,
> +	.release		= single_release,
> +};
> +
> +void cdns3_debugfs_init(struct cdns3 *cdns)
> +{
> +	struct dentry *root;
> +
> +	root = debugfs_create_dir(dev_name(cdns->dev), NULL);
> +	cdns->root = root;
> +	if (IS_ENABLED(CONFIG_USB_CDNS3_GADGET) &&
> +	    IS_ENABLED(CONFIG_USB_CDNS3_HOST))
> +		debugfs_create_file("mode", 0644, root, cdns,
> +				    &cdns3_mode_fops);
> +}
> +
> +void cdns3_debugfs_exit(struct cdns3 *cdns)
> +{
> +	debugfs_remove_recursive(cdns->root);
> +}
> diff --git a/drivers/usb/cdns3/drd.h b/drivers/usb/cdns3/drd.h
> index 85731f3b693c..5344290c76f2 100644
> --- a/drivers/usb/cdns3/drd.h
> +++ b/drivers/usb/cdns3/drd.h
> @@ -119,4 +119,7 @@ int cdns3_drd_probe(struct cdns3 *cdns);
>  void cdns3_set_hw_mode(struct cdns3 *cdns, u32 mode);
>  irqreturn_t cdns3_drd_irq(struct cdns3 *cdns);
>  
> +void cdns3_debugfs_init(struct cdns3 *cdns);
> +void cdns3_debugfs_exit(struct cdns3 *cdns);
> +
>  #endif /* __LINUX_CDNS3_DRD */
> 

cheers,
-roger
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