Date:   Sat, 4 Aug 2018 06:37:09 +0000
From:   Pawel Laszczak <pawell@...ence.com>
To:     Roger Quadros <rogerq@...com>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        Felipe Balbi <balbi@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Lukasz Tyrala <ltyrala@...ence.com>,
        Alan Douglas <adouglas@...ence.com>
Subject: RE: [PATCH 06/31] usb: usbssp: added template functions used by upper
 layer.

> > Patch adds some functionality for initialization process.
> > It adds to driver usbssp_reset and usbssp_start function.
> >
> > Next elements added are objects usbssp_gadget_ep0_ops,
> > usbssp_gadget_ep_ops and usbssp_gadget_ops. These objects
> > constitute the interface used by gadget subsystem.
> > At this moment functions related to these objects are empty
> > and do nothing.
> >
> > This patch also implements usbssp_gadget_init_endpoint and
> > usbssp_gadget_free_endpoint used during initialization.
> >
> > Signed-off-by: Pawel Laszczak <pawell@...ence.com>
> > ---
> >  drivers/usb/usbssp/gadget-ext-caps.h |   3 +
> >  drivers/usb/usbssp/gadget-if.c       | 269 ++++++++++++++++++++++++++-
> >  drivers/usb/usbssp/gadget.c          |  84 ++++++++-
> >  3 files changed, 350 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/usb/usbssp/gadget-ext-caps.h b/drivers/usb/usbssp/gadget-ext-caps.h
> > index 2bf327046376..86c0ce331037 100644
> > --- a/drivers/usb/usbssp/gadget-ext-caps.h
> > +++ b/drivers/usb/usbssp/gadget-ext-caps.h
> > @@ -51,3 +51,6 @@
> >  #define USBSSP_CMD_EWE			BIT(10)
> >
> >  #define USBSSP_IRQS	(USBSSP_CMD_EIE | USBSSP_CMD_HSEIE | USBSSP_CMD_EWE)
> > +
> > +/* true: Controller Not Ready to accept doorbell or op reg writes after reset */
> > +#define USBSSP_STS_CNR			BIT(11)
> > diff --git a/drivers/usb/usbssp/gadget-if.c b/drivers/usb/usbssp/gadget-if.c
> > index d53e0fb65299..70def978b085 100644
> > --- a/drivers/usb/usbssp/gadget-if.c
> > +++ b/drivers/usb/usbssp/gadget-if.c
> > @@ -12,13 +12,278 @@
> >  #include <linux/usb/composite.h>
> >  #include "gadget.h"
> >
> > +static int usbssp_gadget_ep_enable(struct usb_ep *ep,
> > +				   const struct usb_endpoint_descriptor *desc)
> > +{
> > +	struct usbssp_ep *ep_priv = to_usbssp_ep(ep);
> > +	int ret = 0;
> > +
> > +	if (!ep_priv)
> > +		return -EINVAL;
> > +
> > +	/*TODO: implements this function*/
> > +	return ret;
> > +}
> > +
> > +int usbssp_gadget_ep_disable(struct usb_ep *ep)
> > +{
> > +	struct usbssp_ep *ep_priv = to_usbssp_ep(ep);
> > +	int ret = 0;
> > +
> > +	if (!ep_priv)
> > +		return -EINVAL;
> > +
> > +	/*TODO: implements this function*/
> > +	return ret;
> > +}
> > +
> > +static struct usb_request *usbssp_gadget_ep_alloc_request(struct usb_ep *ep,
> > +							  gfp_t gfp_flags)
> > +{
> > +	struct usbssp_ep *ep_priv = to_usbssp_ep(ep);
> > +
> > +	if (!ep_priv)
> > +		return NULL;
> > +
> > +	/*TODO: implements this function*/
> > +	return NULL;
> > +}
> > +
> > +static void usbssp_gadget_ep_free_request(struct usb_ep *ep,
> > +					  struct usb_request *request)
> > +{
> > +	struct usbssp_ep *ep_priv = to_usbssp_ep(ep);
> > +
> > +	if (!ep_priv)
> > +		return;
> > +
> > +	/*TODO: implements this function*/
> > +}
> > +
> > +static int usbssp_gadget_ep_queue(struct usb_ep *ep,
> > +				  struct usb_request *request,
> > +				  gfp_t gfp_flags)
> > +{
> > +	struct usbssp_ep *ep_priv = to_usbssp_ep(ep);
> > +	int ret = 0;
> > +
> > +	if (!ep_priv)
> > +		return -EINVAL;
> > +
> > +	/*TODO: implements this function*/
> > +	return ret;
> > +}
> > +
> > +static int usbssp_gadget_ep_dequeue(struct usb_ep *ep,
> > +				    struct usb_request *request)
> > +{
> > +	struct usbssp_ep *ep_priv = to_usbssp_ep(ep);
> > +	int ret = 0;
> > +
> > +	if (!ep_priv)
> > +		return -EINVAL;
> > +
> > +	/*TODO: implements this function*/
> > +	return ret;
> > +}
> > +
> > +static int usbssp_gadget_ep_set_halt(struct usb_ep *ep, int value)
> > +{
> > +	struct usbssp_ep *ep_priv = to_usbssp_ep(ep);
> > +	int ret = 0;
> > +
> > +	if (!ep_priv)
> > +		return -EINVAL;
> > +
> > +	/*TODO: implements this function*/
> > +	return ret;
> > +}
> > +
> > +static int usbssp_gadget_ep_set_wedge(struct usb_ep *ep)
> > +{
> > +	struct usbssp_ep *ep_priv = to_usbssp_ep(ep);
> > +	int ret = 0;
> > +
> > +	if (!ep_priv)
> > +		return -EINVAL;
> > +
> > +	/*TODO: implements this function*/
> > +	return ret;
> > +}
> > +
> > +static const struct usb_ep_ops usbssp_gadget_ep0_ops = {
> > +	.enable		= usbssp_gadget_ep_enable,
> > +	.disable	= usbssp_gadget_ep_disable,
> > +	.alloc_request	= usbssp_gadget_ep_alloc_request,
> > +	.free_request	= usbssp_gadget_ep_free_request,
> > +	.queue		= usbssp_gadget_ep_queue,
> > +	.dequeue	= usbssp_gadget_ep_dequeue,
> > +	.set_halt	= usbssp_gadget_ep_set_halt,
> > +	.set_wedge	= usbssp_gadget_ep_set_wedge,
> > +};
> > +
> > +static const struct usb_ep_ops usbssp_gadget_ep_ops = {
> > +	.enable		= usbssp_gadget_ep_enable,
> > +	.disable	= usbssp_gadget_ep_disable,
> > +	.alloc_request	= usbssp_gadget_ep_alloc_request,
> > +	.free_request	= usbssp_gadget_ep_free_request,
> > +	.queue		= usbssp_gadget_ep_queue,
> > +	.dequeue	= usbssp_gadget_ep_dequeue,
> > +	.set_halt	= usbssp_gadget_ep_set_halt,
> > +	.set_wedge	= usbssp_gadget_ep_set_wedge,
> > +};
> > +
> > +static struct usb_endpoint_descriptor usbssp_gadget_ep0_desc = {
> > +	.bLength =		USB_DT_ENDPOINT_SIZE,
> > +	.bDescriptorType =	USB_DT_ENDPOINT,
> > +	.bmAttributes =		USB_ENDPOINT_XFER_CONTROL,
> > +};
> > +
> > +static int usbssp_gadget_start(struct usb_gadget *g,
> > +			       struct usb_gadget_driver *driver)
> > +{
> > +	struct usbssp_udc *usbssp_data = gadget_to_usbssp(g);
> > +	int ret = 0;
> > +
> > +	if (usbssp_data->gadget_driver) {
> > +		dev_err(usbssp_data->dev, "%s is already bound to %s\n",
> > +				usbssp_data->gadget.name,
> > +				usbssp_data->gadget_driver->driver.name);
> > +		ret = -EBUSY;
> > +	}
> > +
> > +	/*TODO: add implementation*/
> > +	return ret;
> > +}
> > +
> > +static int usbssp_gadget_stop(struct usb_gadget *g)
> > +{
> > +	struct usbssp_udc *usbssp_data = gadget_to_usbssp(g);
> > +
> > +	if (!usbssp_data)
> > +		return -EINVAL;
> > +	/*TODO: add implementation*/
> > +	return 0;
> > +}
> > +
> > +static int usbssp_gadget_get_frame(struct usb_gadget *g)
> > +{
> > +	struct usbssp_udc *usbssp_data = gadget_to_usbssp(g);
> > +
> > +	if (!usbssp_data)
> > +		return -EINVAL;
> > +
> > +	/*TODO: add implementation*/
> > +	return 0;
> > +}
> > +
> > +static int usbssp_gadget_wakeup(struct usb_gadget *g)
> > +{
> > +	struct usbssp_udc *usbssp_data = gadget_to_usbssp(g);
> > +
> > +	if (!usbssp_data)
> > +		return -EINVAL;
> > +
> > +	/*TODO: add implementation*/
> > +	return 0;
> > +}
> > +
> > +static int usbssp_gadget_set_selfpowered(struct usb_gadget *g,
> > +					 int is_selfpowered)
> > +{
> > +	struct usbssp_udc *usbssp_data = gadget_to_usbssp(g);
> > +
> > +	if (!usbssp_data)
> > +		return -EINVAL;
> > +
> > +	/*TODO: add implementation*/
> > +	return 0;
> > +}
> > +
> > +static const struct usb_gadget_ops usbssp_gadget_ops = {
> > +	.get_frame		= usbssp_gadget_get_frame,
> > +	.wakeup			= usbssp_gadget_wakeup,
> > +	.set_selfpowered	= usbssp_gadget_set_selfpowered,
> > +	.udc_start		= usbssp_gadget_start,
> > +	.udc_stop		= usbssp_gadget_stop,
> > +};
> > +
> >  int usbssp_gadget_init_endpoint(struct usbssp_udc *usbssp_data)
> 
> Since we're initializing all endpoints this function should be named usbssp_gadget_init_endpoints().
> 
> >  {
> > -	/*TODO: it has to be implemented*/
> > +	int i = 0;
> > +	struct usbssp_ep *ep_priv;
> > +
> > +	usbssp_data->num_endpoints = USBSSP_ENDPOINTS_NUM;
> > +	INIT_LIST_HEAD(&usbssp_data->gadget.ep_list);
> > +
> > +	for (i = 1; i < usbssp_data->num_endpoints; i++) {
> > +		bool direction = i & 1; /*start from OUT endpoint*/
> > +		u8 epnum = (i >> 1);
> > +
> > +		ep_priv = &usbssp_data->devs.eps[i-1];
> > +		ep_priv->usbssp_data = usbssp_data;
> > +		ep_priv->number = epnum;
> > +		ep_priv->direction = direction; /*0 for OUT, 1 for IN*/
> > +
> > +		snprintf(ep_priv->name, sizeof(ep_priv->name), "ep%d%s", epnum,
> > +				(ep_priv->direction) ? "in" : "out");
> > +
> > +		ep_priv->endpoint.name = ep_priv->name;
> > +
> > +		if (ep_priv->number < 2) {
> > +			ep_priv->endpoint.desc = &usbssp_gadget_ep0_desc;
> > +			ep_priv->endpoint.comp_desc = NULL;
> > +		}
> > +
> > +		if (epnum == 0) {
> > +			/*EP0 is bidirectional endpoint*/
> > +			usb_ep_set_maxpacket_limit(&ep_priv->endpoint, 512);
> > +			dev_dbg(usbssp_data->dev,
> > +				"Initializing %s, MaxPack: %04x Type: Ctrl\n",
> > +				ep_priv->name, 512);
> > +			ep_priv->endpoint.maxburst = 1;
> > +			ep_priv->endpoint.ops = &usbssp_gadget_ep0_ops;
> > +			ep_priv->endpoint.caps.type_control = true;
> > +
> > +			usbssp_data->usb_req_ep0_in.epnum = ep_priv->number;
> > +			usbssp_data->usb_req_ep0_in.dep = ep_priv;
> > +
> > +			if (!epnum)
> > +				usbssp_data->gadget.ep0 = &ep_priv->endpoint;
> > +		} else {
> > +			usb_ep_set_maxpacket_limit(&ep_priv->endpoint, 1024);
> > +			ep_priv->endpoint.maxburst = 15;
> > +			ep_priv->endpoint.ops = &usbssp_gadget_ep_ops;
> > +			list_add_tail(&ep_priv->endpoint.ep_list,
> > +					&usbssp_data->gadget.ep_list);
> > +			ep_priv->endpoint.caps.type_iso = true;
> > +			ep_priv->endpoint.caps.type_bulk = true;
> > +			ep_priv->endpoint.caps.type_int = true;
> > +
> > +		}
> > +
> > +		ep_priv->endpoint.caps.dir_in = direction;
> > +		ep_priv->endpoint.caps.dir_out = !direction;
> 
> Since you start from 1, ep0 will only be initialized as dir_in.
> Is it better to represent EP0in and EP0out separately?
> If so you can start i from 0 and use
> 	ep_priv = &usbssp_data->devs.eps[i];
> 
> This should fix the direction. eps[0] will be ep0out and eps[1] will be ep0in.

I wanted to be consistent with Device Context Data Structure from 
XHCI specification (EP Context 0 BiDir, EP Context 1 OUT, EP Context 1 IN ...).

I little change this function, and now it look like this:
int usbssp_gadget_init_endpoints(struct usbssp_udc *usbssp_data)
{
	int i = 0;
	struct usbssp_ep *ep_priv;

	usbssp_data->num_endpoints = USBSSP_ENDPOINTS_NUM;
	INIT_LIST_HEAD(&usbssp_data->gadget.ep_list);

	for (i = 0; i < usbssp_data->num_endpoints; i++) {
		bool direction = i & 1; /*start from OUT endpoint*/
		u8 epnum = ((i + 1) >> 1);

		ep_priv = &usbssp_data->devs.eps[i];
		ep_priv->usbssp_data = usbssp_data;
		ep_priv->number = epnum;
		ep_priv->direction = direction; /*0 for OUT, 1 for IN*/

		/*
		 *Ep0 is bidirectional so Ep0In and Ep0Out is represented by
		 * usbssp_data->devs.eps[0]
		 */
		if (epnum == 0) {
			snprintf(ep_priv->name, sizeof(ep_priv->name), "ep%d%s",
				epnum, "BiDir");

			usb_ep_set_maxpacket_limit(&ep_priv->endpoint, 512);
			ep_priv->endpoint.maxburst = 1;
			ep_priv->endpoint.ops = &usbssp_gadget_ep0_ops;
			ep_priv->endpoint.desc = &usbssp_gadget_ep0_desc;

			ep_priv->endpoint.comp_desc = NULL;
			ep_priv->endpoint.caps.type_control = true;
			ep_priv->endpoint.caps.dir_in = true;
			ep_priv->endpoint.caps.dir_out = true;

			usbssp_data->usb_req_ep0_in.epnum = ep_priv->number;
			usbssp_data->usb_req_ep0_in.dep = ep_priv;
			usbssp_data->gadget.ep0 = &ep_priv->endpoint;

		} else {
			snprintf(ep_priv->name, sizeof(ep_priv->name), "ep%d%s",
				epnum, (ep_priv->direction) ? "in"  : "out");

			usb_ep_set_maxpacket_limit(&ep_priv->endpoint, 1024);
			ep_priv->endpoint.maxburst = 15;
			ep_priv->endpoint.ops = &usbssp_gadget_ep_ops;
			list_add_tail(&ep_priv->endpoint.ep_list,
					&usbssp_data->gadget.ep_list);

			ep_priv->endpoint.caps.type_iso = true;
			ep_priv->endpoint.caps.type_bulk = true;
			ep_priv->endpoint.caps.type_int = true;

			ep_priv->endpoint.caps.dir_in = direction;
			ep_priv->endpoint.caps.dir_out = !direction;
		}

		ep_priv->endpoint.name = ep_priv->name;

		dev_dbg(usbssp_data->dev, "Init %s, MaxPack: %04x SupType: "
			"CTRL: %s, INT: %s, BULK: %s, ISOC %s, "
			"SupDir IN: %s, OUT: %s\n",
			ep_priv->name, 1024,
			(ep_priv->endpoint.caps.type_control) ? "yes" : "no",
			(ep_priv->endpoint.caps.type_int) ? "yes" : "no",
			(ep_priv->endpoint.caps.type_bulk) ? "yes" : "no",
			(ep_priv->endpoint.caps.type_iso) ? "yes" : "no",
			(ep_priv->endpoint.caps.dir_in) ? "yes" : "no",
			(ep_priv->endpoint.caps.dir_out) ? "yes" : "no");

		INIT_LIST_HEAD(&ep_priv->pending_list);
	}

	return 0;
}

> > +
> > +		dev_dbg(usbssp_data->dev, "Init %s, MaxPack: %04x SupType:"
> > +				" INT/BULK/ISOC , SupDir %s\n",
> > +				ep_priv->name, 1024,
> > +				(ep_priv->endpoint.caps.dir_in) ? "IN" : "OUT");
> > +
> > +		INIT_LIST_HEAD(&ep_priv->pending_list);
> > +	}
> >  	return 0;
> >  }
> >
> >  void usbssp_gadget_free_endpoint(struct usbssp_udc *usbssp_data)
> >  {
> > -	/*TODO: it has to be implemented*/
> > +	int i;
> > +	struct usbssp_ep *ep_priv;
> > +
> > +	for (i = 0; i < usbssp_data->num_endpoints; i++) {
> > +		ep_priv = &usbssp_data->devs.eps[i];
> > +
> 
> if you start i from 1 then you can skip the if().
> 
> > +		if (ep_priv->number != 0)
> > +			list_del(&ep_priv->endpoint.ep_list);
> > +	}
> >  }
> > diff --git a/drivers/usb/usbssp/gadget.c b/drivers/usb/usbssp/gadget.c
> > index 338ec2ec18b1..195f5777cf8a 100644
> > --- a/drivers/usb/usbssp/gadget.c
> > +++ b/drivers/usb/usbssp/gadget.c
> > @@ -103,6 +103,83 @@ int usbssp_halt(struct usbssp_udc *usbssp_data)
> >  	return ret;
> >  }
> >
> > +/*
> > + * Set the run bit and wait for the device to be running.
> > + */
> > +int usbssp_start(struct usbssp_udc *usbssp_data)
> > +{
> > +	u32 temp;
> > +	int ret;
> > +
> > +	temp = readl(&usbssp_data->op_regs->command);
> > +	temp |= (CMD_RUN | CMD_DEVEN);
> > +	usbssp_dbg_trace(usbssp_data, trace_usbssp_dbg_init,
> > +			"// Turn on USBSSP, cmd = 0x%x.", temp);
> > +	writel(temp, &usbssp_data->op_regs->command);
> > +
> > +	/*
> > +	 * Wait for the HCHalted Staus bit to be 0 to indicate the device is
> > +	 * running.
> > +	 */
> > +	ret = usbssp_handshake(&usbssp_data->op_regs->status,
> > +			STS_HALT, 0, USBSSP_MAX_HALT_USEC);
> > +
> > +	if (ret == -ETIMEDOUT)
> > +		dev_err(usbssp_data->dev, "Device took too long to start, waited %u microseconds.\n",
> > +			USBSSP_MAX_HALT_USEC);
> > +	if (!ret)
> > +		/* clear state flags. Including dying, halted or removing */
> > +		usbssp_data->usbssp_state = 0;
> > +
> > +	return ret;
> > +}
> > +
> > +/*
> > + * Reset a halted DC.
> > + *
> > + * This resets pipelines, timers, counters, state machines, etc.
> > + * Transactions will be terminated immediately, and operational registers
> > + * will be set to their defaults.
> > + */
> > +int usbssp_reset(struct usbssp_udc *usbssp_data)
> > +{
> > +	u32 command;
> > +	u32 state;
> > +	int ret;
> > +
> > +	state = readl(&usbssp_data->op_regs->status);
> > +
> > +	if (state == ~(u32)0) {
> > +		dev_warn(usbssp_data->dev, "Device not accessible, reset failed.\n");
> > +		return -ENODEV;
> > +	}
> > +
> > +	if ((state & STS_HALT) == 0) {
> > +		dev_warn(usbssp_data->dev, "DC not halted, aborting reset.\n");
> 
> DC is not a familiar abbreviation. Mabe just use Controller? or Device controller.

In xhci driver is often used HC for host controller. In device driver I change this abbreviation 
to  DC. I will review the patches and change this to Controller.  

> 
> > +		return 0;
> > +	}
> > +
> > +	usbssp_dbg_trace(usbssp_data, trace_usbssp_dbg_init, "// Reset the DC");
> > +	command = readl(&usbssp_data->op_regs->command);
> > +	command |= CMD_RESET;
> > +	writel(command, &usbssp_data->op_regs->command);
> > +
> > +	ret = usbssp_handshake(&usbssp_data->op_regs->command,
> > +			CMD_RESET, 0, 10 * 1000 * 1000);
> > +
> > +	if (ret)
> > +		return ret;
> > +	usbssp_dbg_trace(usbssp_data, trace_usbssp_dbg_init,
> > +		"Wait for controller to be ready for doorbell rings");
> > +	/*
> > +	 * USBSSP cannot write to any doorbells or operational registers other
> > +	 * than status until the "Controller Not Ready" flag is cleared.
> > +	 */
> > +	ret = usbssp_handshake(&usbssp_data->op_regs->status,
> > +			STS_CNR, 0, 10 * 1000 * 1000);
> > +
> > +	return ret;
> > +}
> >
> >  /*
> >   * Initialize memory for gadget driver and USBSSP (one-time init).
> > @@ -179,8 +256,7 @@ int usbssp_gen_setup(struct usbssp_udc *usbssp_data)
> >
> >  	dev_dbg(usbssp_data->dev, "Resetting Device Controller\n");
> >  	/* Reset the internal DC memory state and registers. */
> > -	/*TODO: add implementation of usbssp_reset function*/
> > -	//retval = usbssp_reset(usbssp_data);
> > +	retval = usbssp_reset(usbssp_data);
> >  	if (retval)
> >  		return retval;
> >  	dev_dbg(usbssp_data->dev, "Reset complete\n");
> > @@ -244,8 +320,7 @@ int usbssp_gadget_init(struct usbssp_udc *usbssp_data)
> >  	BUILD_BUG_ON(sizeof(struct usbssp_run_regs) != (8+8*128)*32/8);
> >
> >  	/* fill gadget fields */
> > -	/*TODO: implements usbssp_gadget_ops object*/
> > -	//usbssp_data->gadget.ops = &usbssp_gadget_ops;
> > +	usbssp_data->gadget.ops = &usbssp_gadget_ops;
> >  	usbssp_data->gadget.name = "usbssp-gadget";
> >  	usbssp_data->gadget.max_speed = USB_SPEED_SUPER_PLUS;
> >  	usbssp_data->gadget.speed = USB_SPEED_UNKNOWN;
> > @@ -288,6 +363,7 @@ int usbssp_gadget_init(struct usbssp_udc *usbssp_data)
> >  	usbssp_halt(usbssp_data);
> >  	/*TODO add implementation of usbssp_reset function*/
> >  	//usbssp_reset(usbssp_data);
> > +	usbssp_reset(usbssp_data);
> >  	/*TODO add implementation of freeing memory*/
> >  	//usbssp_mem_cleanup(usbssp_data);
> >  err3:
> >
> 
> --
> cheers,
> -roger
> 
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

Cheers
Pawel

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