Re: [PATCH v6] usb: gadget: udc: renesas_usb3: Add register of usb role switch

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

On Thu, May 31, 2018 at 03:11:33PM +0900, Yoshihiro Shimoda wrote:
> This patch adds role switch support for R-Car SoCs into the USB 3.0
> peripheral driver. Some R-Car SoCs (e.g. R-Car H3) have USB 3.0
> dual-role device controller which has the USB 3.0 xHCI host and
> Renesas USB 3.0 peripheral.
> 
> Unfortunately, the mode change register (DRD_CON) contains
> the USB 3.0 peripheral controller side only. So, this renesas_usb3
> driver manages the DRD_CON now. However, in peripheral mode, the host
> should stop. Also the host hardware needs to reinitialize its own
> registers when the mode changes from peripheral to host mode.
> Otherwise, the host cannot work correctly (e.g. detect a device
> as high-speed).
> 
> To achieve this reinitialization by a driver, this driver also
> registers a role switch driver to manage the DRD_CON and get
> a device pointer of usb 3.0 host from "companion" property of OF.
> Then, when the usb role is changed, renesas_usb3_role_switch_set()
> will attach/release the xhci-plat driver to reinitialize the host
> hardware.
> 
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
> This patch set is based on Felipe's usb.git / testing/next branch
> (commit id = 47265c067c0d129f3a0e94bc221293a780af9d78).
> 
> Changes from v5 (https://patchwork.kernel.org/patch/10426483/):
>  - Add a new function "usb3_set_mode_by_role_sw()" instead of reusing
>    usb3_set_mode() and add _usb3_set_mode().
>  - Change a coding style of container_of.
>  - Revise an error message in renesas_usb3_role_switch_set().
>  - Add "const" for "renesas_usb3_role_switch_desc".
>  - Simplify a condition check of usb_of_get_companion_dev().
> 
> Changes from RFC v4 (https://patchwork.kernel.org/patch/10418265/):
>  - Use "companion" device tree property simply instead of device_connection
>    APIs with OF graph.
>  - Merge patch 2 and 3 to one.
>  - Revise the commit log (I should had revised this on RFC v4 though).
> 
> Changes from RFC v3:
>  - Rebase latest usb.git / testing/next branch.
>  - Add graph parse into device_connection_find_match().
>  - Use workqueue to call _usb3_set_mode() in patch 3.
>    (I realized renesas_usb3_role_switch_set() cannot run on atomic because
>     device_attach() might sleep.)
> 
> Changes from RFC v2:
>  - Add registering usb role switch into drivers/usb/gadget/udc/renesas_usb3
>    because hardware resource (a register) is shared and remove individual
>    usb role switch driver/dt-bindings for R-Car.
>  - Remove "usb_role_switch_get_by_graph" API because the renesas_usb3 driver
>    doesn't need such API now.
> 
> Changes from RFC:
>  - Remove "device-connection-id" and "usb role switch driver" dt-bingings.
>  - Remove drivers/of code.
>  - Add a new API for find the connection by using graph on devcon.c and roles.c.
>  - Use each new API on the rcar usb role switch and renesas_usb3 drivers.
>  - Update the dtsi file for r8a7795.
> 
> 
>  drivers/usb/gadget/udc/Kconfig        |  1 +
>  drivers/usb/gadget/udc/renesas_usb3.c | 84 ++++++++++++++++++++++++++++++++++-
>  2 files changed, 84 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/gadget/udc/Kconfig b/drivers/usb/gadget/udc/Kconfig
> index b838cae..78823cd 100644
> --- a/drivers/usb/gadget/udc/Kconfig
> +++ b/drivers/usb/gadget/udc/Kconfig
> @@ -193,6 +193,7 @@ config USB_RENESAS_USB3
>  	tristate 'Renesas USB3.0 Peripheral controller'
>  	depends on ARCH_RENESAS || COMPILE_TEST
>  	depends on EXTCON && HAS_DMA
> +	select USB_ROLE_SWITCH
>  	help
>  	   Renesas USB3.0 Peripheral controller is a USB peripheral controller
>  	   that supports super, high, and full speed USB 3.0 data transfers.
> diff --git a/drivers/usb/gadget/udc/renesas_usb3.c b/drivers/usb/gadget/udc/renesas_usb3.c
> index 5caf78b..f44a4b1 100644
> --- a/drivers/usb/gadget/udc/renesas_usb3.c
> +++ b/drivers/usb/gadget/udc/renesas_usb3.c
> @@ -23,6 +23,8 @@
>  #include <linux/uaccess.h>
>  #include <linux/usb/ch9.h>
>  #include <linux/usb/gadget.h>
> +#include <linux/usb/of.h>
> +#include <linux/usb/role.h>
>  
>  /* register definitions */
>  #define USB3_AXI_INT_STA	0x008
> @@ -335,6 +337,11 @@ struct renesas_usb3 {
>  	struct phy *phy;
>  	struct dentry *dentry;
>  
> +	struct usb_role_switch *role_sw;
> +	struct device *host_dev;
> +	struct work_struct role_work;
> +	enum usb_role role;
> +
>  	struct renesas_usb3_ep *usb3_ep;
>  	int num_usb3_eps;
>  
> @@ -651,6 +658,14 @@ static void usb3_check_vbus(struct renesas_usb3 *usb3)
>  	}
>  }
>  
> +static void renesas_usb3_role_work(struct work_struct *work)
> +{
> +	struct renesas_usb3 *usb3 =
> +			container_of(work, struct renesas_usb3, role_work);
> +
> +	usb_role_switch_set_role(usb3->role_sw, usb3->role);
> +}
> +
>  static void usb3_set_mode(struct renesas_usb3 *usb3, bool host)
>  {
>  	if (host)
> @@ -659,6 +674,16 @@ static void usb3_set_mode(struct renesas_usb3 *usb3, bool host)
>  		usb3_set_bit(usb3, DRD_CON_PERI_CON, USB3_DRD_CON);
>  }
>  
> +static void usb3_set_mode_by_role_sw(struct renesas_usb3 *usb3, bool host)
> +{
> +	if (usb3->role_sw) {
> +		usb3->role = host ? USB_ROLE_HOST : USB_ROLE_DEVICE;
> +		schedule_work(&usb3->role_work);
> +	} else {
> +		usb3_set_mode(usb3, host);
> +	}
> +}
> +
>  static void usb3_vbus_out(struct renesas_usb3 *usb3, bool enable)
>  {
>  	if (enable)
> @@ -672,7 +697,7 @@ static void usb3_mode_config(struct renesas_usb3 *usb3, bool host, bool a_dev)
>  	unsigned long flags;
>  
>  	spin_lock_irqsave(&usb3->lock, flags);
> -	usb3_set_mode(usb3, host);
> +	usb3_set_mode_by_role_sw(usb3, host);
>  	usb3_vbus_out(usb3, a_dev);
>  	/* for A-Peripheral or forced B-device mode */
>  	if ((!host && a_dev) ||
> @@ -2302,6 +2327,41 @@ static int renesas_usb3_set_selfpowered(struct usb_gadget *gadget, int is_self)
>  	.set_selfpowered	= renesas_usb3_set_selfpowered,
>  };
>  
> +static enum usb_role renesas_usb3_role_switch_get(struct device *dev)
> +{
> +	struct renesas_usb3 *usb3 = dev_get_drvdata(dev);
> +	enum usb_role cur_role;
> +
> +	pm_runtime_get_sync(dev);
> +	cur_role = usb3_is_host(usb3) ? USB_ROLE_HOST : USB_ROLE_DEVICE;
> +	pm_runtime_put(dev);
> +
> +	return cur_role;
> +}
> +
> +static int renesas_usb3_role_switch_set(struct device *dev,
> +					enum usb_role role)
> +{
> +	struct renesas_usb3 *usb3 = dev_get_drvdata(dev);
> +	struct device *host = usb3->host_dev;
> +	enum usb_role cur_role = renesas_usb3_role_switch_get(dev);
> +
> +	pm_runtime_get_sync(dev);
> +	if (cur_role == USB_ROLE_HOST && role == USB_ROLE_DEVICE) {
> +		device_release_driver(host);
> +		usb3_set_mode(usb3, false);
> +	} else if (cur_role == USB_ROLE_DEVICE && role == USB_ROLE_HOST) {
> +		/* Must set the mode before device_attach of the host */
> +		usb3_set_mode(usb3, true);
> +		/* This device_attach() might sleep */
> +		if (device_attach(host) < 0)
> +			dev_err(dev, "device_attach(host) failed\n");
> +	}
> +	pm_runtime_put(dev);
> +
> +	return 0;
> +}
> +
>  static ssize_t role_store(struct device *dev, struct device_attribute *attr,
>  			  const char *buf, size_t count)
>  {
> @@ -2417,6 +2477,8 @@ static int renesas_usb3_remove(struct platform_device *pdev)
>  	debugfs_remove_recursive(usb3->dentry);
>  	device_remove_file(&pdev->dev, &dev_attr_role);
>  
> +	usb_role_switch_unregister(usb3->role_sw);
> +
>  	usb_del_gadget_udc(&usb3->gadget);
>  	renesas_usb3_dma_free_prd(usb3, &pdev->dev);
>  
> @@ -2573,6 +2635,12 @@ static void renesas_usb3_init_ram(struct renesas_usb3 *usb3, struct device *dev,
>  	EXTCON_NONE,
>  };
>  
> +static const struct usb_role_switch_desc renesas_usb3_role_switch_desc = {
> +	.set = renesas_usb3_role_switch_set,
> +	.get = renesas_usb3_role_switch_get,
> +	.allow_userspace_control = true,
> +};
> +
>  static int renesas_usb3_probe(struct platform_device *pdev)
>  {
>  	struct renesas_usb3 *usb3;
> @@ -2658,6 +2726,20 @@ static int renesas_usb3_probe(struct platform_device *pdev)
>  	if (ret < 0)
>  		goto err_dev_create;
>  
> +	INIT_WORK(&usb3->role_work, renesas_usb3_role_work);
> +	usb3->role_sw = usb_role_switch_register(&pdev->dev,
> +					&renesas_usb3_role_switch_desc);
> +	if (!IS_ERR(usb3->role_sw)) {
> +		usb3->host_dev = usb_of_get_companion_dev(&pdev->dev);
> +		if (!usb3->host_dev) {
> +			/* If not found, this driver will not use a role sw */
> +			usb_role_switch_unregister(usb3->role_sw);
> +			usb3->role_sw = NULL;
> +		}
> +	} else {
> +		usb3->role_sw = NULL;
> +	}
> +
>  	usb3->workaround_for_vbus = priv->workaround_for_vbus;
>  
>  	renesas_usb3_debugfs_init(usb3, &pdev->dev);

-- 
heikki