greybus: es2: add ES2 Greybus Host driver

obj-m += gb-vibrator.o

obj-m += gb-battery.o

obj-m += gb-es1.o

obj-m += gb-es2.o

KERNELVER		?= $(shell uname -r)

KERNELDIR 		?= /lib/modules/$(KERNELVER)/build

/*

 * Greybus "AP" USB driver for "ES2" controller chips

 *

 * Copyright 2014 Google Inc.

 * Copyright 2014 Linaro Ltd.

 *

 * Released under the GPLv2 only.

 */

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/slab.h>

#include <linux/errno.h>

#include <linux/sizes.h>

#include <linux/usb.h>

#include "greybus.h"

#include "svc_msg.h"

#include "kernel_ver.h"

/*

 * Macros for making pointers explicitly opaque, such that the result

 * isn't valid but also can't be mistaken for an ERR_PTR() value.

 */

#define conceal_urb(urb)	((void *)((uintptr_t)(urb) ^ 0xbad))

#define reveal_urb(cookie)	((void *)((uintptr_t)(cookie) ^ 0xbad))

/* Memory sizes for the buffers sent to/from the ES1 controller */

#define ES1_SVC_MSG_SIZE	(sizeof(struct svc_msg) + SZ_64K)

#define ES1_GBUF_MSG_SIZE_MAX	PAGE_SIZE

static const struct usb_device_id id_table[] = {

	/* Made up numbers for the SVC USB Bridge in ES1 */

	{ USB_DEVICE(0xffff, 0x0001) },

	{ },

};

MODULE_DEVICE_TABLE(usb, id_table);

/*

 * Number of CPort IN urbs in flight at any point in time.

 * Adjust if we are having stalls in the USB buffer due to not enough urbs in

 * flight.

 */

#define NUM_CPORT_IN_URB	4

/* Number of CPort OUT urbs in flight at any point in time.

 * Adjust if we get messages saying we are out of urbs in the system log.

 */

#define NUM_CPORT_OUT_URB	8

/**

 * es1_ap_dev - ES1 USB Bridge to AP structure

 * @usb_dev: pointer to the USB device we are.

 * @usb_intf: pointer to the USB interface we are bound to.

 * @hd: pointer to our greybus_host_device structure

 * @control_endpoint: endpoint to send data to SVC

 * @svc_endpoint: endpoint for SVC data in

 * @cport_in_endpoint: bulk in endpoint for CPort data

 * @cport-out_endpoint: bulk out endpoint for CPort data

 * @svc_buffer: buffer for SVC messages coming in on @svc_endpoint

 * @svc_urb: urb for SVC messages coming in on @svc_endpoint

 * @cport_in_urb: array of urbs for the CPort in messages

 * @cport_in_buffer: array of buffers for the @cport_in_urb urbs

 * @cport_out_urb: array of urbs for the CPort out messages

 * @cport_out_urb_busy: array of flags to see if the @cport_out_urb is busy or

 *			not.

 * @cport_out_urb_lock: locks the @cport_out_urb_busy "list"

 */

struct es1_ap_dev {

	struct usb_device *usb_dev;

	struct usb_interface *usb_intf;

	struct greybus_host_device *hd;

	__u8 control_endpoint;

	__u8 svc_endpoint;

	__u8 cport_in_endpoint;

	__u8 cport_out_endpoint;

	u8 *svc_buffer;

	struct urb *svc_urb;

	struct urb *cport_in_urb[NUM_CPORT_IN_URB];

	u8 *cport_in_buffer[NUM_CPORT_IN_URB];

	struct urb *cport_out_urb[NUM_CPORT_OUT_URB];

	bool cport_out_urb_busy[NUM_CPORT_OUT_URB];

	spinlock_t cport_out_urb_lock;

};

static inline struct es1_ap_dev *hd_to_es1(struct greybus_host_device *hd)

{

	return (struct es1_ap_dev *)&hd->hd_priv;

}

static void cport_out_callback(struct urb *urb);

/*

 * Buffer constraints for the host driver.

 *

 * A "buffer" is used to hold data to be transferred for Greybus by

 * the host driver.  A buffer is represented by a "buffer pointer",

 * which defines a region of memory used by the host driver for

 * transferring the data.  When Greybus allocates a buffer, it must

 * do so subject to the constraints associated with the host driver.

 * These constraints are specified by two parameters: the

 * headroom; and the maximum buffer size.

 *

 *			+------------------+

 *			|    Host driver   | \

 *			|   reserved area  |  }- headroom

 *			|      . . .       | /

 *  buffer pointer ---> +------------------+

 *			| Buffer space for | \

 *			| transferred data |  }- buffer size

 *			|      . . .       | /   (limited to size_max)

 *			+------------------+

 *

 *  headroom:	Every buffer must have at least this much space

 *		*before* the buffer pointer, reserved for use by the

 *		host driver.  I.e., ((char *)buffer - headroom) must

 *		point to valid memory, usable only by the host driver.

 *  size_max:	The maximum size of a buffer (not including the

 *  		headroom) must not exceed this.

 */

static void hd_buffer_constraints(struct greybus_host_device *hd)

{

	/*

	 * Only one byte is required, but this produces a result

	 * that's better aligned for the user.

	 */

	hd->buffer_headroom = sizeof(u32);	/* For cport id */

	hd->buffer_size_max = ES1_GBUF_MSG_SIZE_MAX;

	BUILD_BUG_ON(hd->buffer_headroom > GB_BUFFER_HEADROOM_MAX);

}

#define ES1_TIMEOUT	500	/* 500 ms for the SVC to do something */

static int submit_svc(struct svc_msg *svc_msg, struct greybus_host_device *hd)

{

	struct es1_ap_dev *es1 = hd_to_es1(hd);

	int retval;

	/* SVC messages go down our control pipe */

	retval = usb_control_msg(es1->usb_dev,

				 usb_sndctrlpipe(es1->usb_dev,

						 es1->control_endpoint),

				 0x01,	/* vendor request AP message */

				 USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,

				 0x00, 0x00,

				 (char *)svc_msg,

				 sizeof(*svc_msg),

				 ES1_TIMEOUT);

	if (retval != sizeof(*svc_msg))

		return retval;

	return 0;

}

static struct urb *next_free_urb(struct es1_ap_dev *es1, gfp_t gfp_mask)

{

	struct urb *urb = NULL;

	unsigned long flags;

	int i;

	spin_lock_irqsave(&es1->cport_out_urb_lock, flags);

	/* Look in our pool of allocated urbs first, as that's the "fastest" */

	for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {

		if (es1->cport_out_urb_busy[i] == false) {

			es1->cport_out_urb_busy[i] = true;

			urb = es1->cport_out_urb[i];

			break;

		}

	}

	spin_unlock_irqrestore(&es1->cport_out_urb_lock, flags);

	if (urb)

		return urb;

	/*

	 * Crap, pool is empty, complain to the syslog and go allocate one

	 * dynamically as we have to succeed.

	 */

	dev_err(&es1->usb_dev->dev,

		"No free CPort OUT urbs, having to dynamically allocate one!\n");

	return usb_alloc_urb(0, gfp_mask);

}

static void free_urb(struct es1_ap_dev *es1, struct urb *urb)

{

	unsigned long flags;

	int i;

	/*

	 * See if this was an urb in our pool, if so mark it "free", otherwise

	 * we need to free it ourselves.

	 */

	spin_lock_irqsave(&es1->cport_out_urb_lock, flags);

	for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {

		if (urb == es1->cport_out_urb[i]) {

			es1->cport_out_urb_busy[i] = false;

			urb = NULL;

			break;

		}

	}

	spin_unlock_irqrestore(&es1->cport_out_urb_lock, flags);

	/* If urb is not NULL, then we need to free this urb */

	usb_free_urb(urb);

}

/*

 * Returns an opaque cookie value if successful, or a pointer coded

 * error otherwise.  If the caller wishes to cancel the in-flight

 * buffer, it must supply the returned cookie to the cancel routine.

 */

static void *buffer_send(struct greybus_host_device *hd, u16 cport_id,

			void *buffer, size_t buffer_size, gfp_t gfp_mask)

{

	struct es1_ap_dev *es1 = hd_to_es1(hd);

	struct usb_device *udev = es1->usb_dev;

	u8 *transfer_buffer = buffer;

	int transfer_buffer_size;

	int retval;

	struct urb *urb;

	if (!buffer) {

		pr_err("null buffer supplied to send\n");

		return ERR_PTR(-EINVAL);

	}

	if (buffer_size > (size_t)INT_MAX) {

		pr_err("bad buffer size (%zu) supplied to send\n", buffer_size);

		return ERR_PTR(-EINVAL);

	}

	transfer_buffer--;

	transfer_buffer_size = buffer_size + 1;

	/*

	 * The data actually transferred will include an indication

	 * of where the data should be sent.  Do one last check of

	 * the target CPort id before filling it in.

	 */

	if (cport_id == CPORT_ID_BAD) {

		pr_err("request to send inbound data buffer\n");

		return ERR_PTR(-EINVAL);

	}

	if (cport_id > (u16)U8_MAX) {

		pr_err("cport_id (%hd) is out of range for ES1\n", cport_id);

		return ERR_PTR(-EINVAL);

	}

	/* OK, the destination is fine; record it in the transfer buffer */

	*transfer_buffer = cport_id;

	/* Find a free urb */

	urb = next_free_urb(es1, gfp_mask);

	if (!urb)

		return ERR_PTR(-ENOMEM);

	usb_fill_bulk_urb(urb, udev,

			  usb_sndbulkpipe(udev, es1->cport_out_endpoint),

			  transfer_buffer, transfer_buffer_size,

			  cport_out_callback, hd);

	retval = usb_submit_urb(urb, gfp_mask);

	if (retval) {

		pr_err("error %d submitting URB\n", retval);

		free_urb(es1, urb);

		return ERR_PTR(retval);

	}

	return conceal_urb(urb);

}

/*

 * The cookie value supplied is the value that buffer_send()

 * returned to its caller.  It identifies the buffer that should be

 * canceled.  This function must also handle (which is to say,

 * ignore) a null cookie value.

 */

static void buffer_cancel(void *cookie)

{

	/*

	 * We really should be defensive and track all outstanding

	 * (sent) buffers rather than trusting the cookie provided

	 * is valid.  For the time being, this will do.

	 */

	if (cookie)

		usb_kill_urb(reveal_urb(cookie));

}

static struct greybus_host_driver es1_driver = {

	.hd_priv_size		= sizeof(struct es1_ap_dev),

	.buffer_send		= buffer_send,

	.buffer_cancel		= buffer_cancel,

	.submit_svc		= submit_svc,

};

/* Common function to report consistent warnings based on URB status */

static int check_urb_status(struct urb *urb)

{

	struct device *dev = &urb->dev->dev;

	int status = urb->status;

	switch (status) {

	case 0:

		return 0;

	case -EOVERFLOW:

		dev_err(dev, "%s: overflow actual length is %d\n",

			__func__, urb->actual_length);

	case -ECONNRESET:

	case -ENOENT:

	case -ESHUTDOWN:

	case -EILSEQ:

	case -EPROTO:

		/* device is gone, stop sending */

		return status;

	}

	dev_err(dev, "%s: unknown status %d\n", __func__, status);

	return -EAGAIN;

}

static void ap_disconnect(struct usb_interface *interface)

{

	struct es1_ap_dev *es1;

	struct usb_device *udev;

	int i;

	es1 = usb_get_intfdata(interface);

	if (!es1)

		return;

	/* Tear down everything! */

	for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {

		struct urb *urb = es1->cport_out_urb[i];

		if (!urb)

			break;

		usb_kill_urb(urb);

		usb_free_urb(urb);

		es1->cport_out_urb[i] = NULL;

		es1->cport_out_urb_busy[i] = false;	/* just to be anal */

	}

	for (i = 0; i < NUM_CPORT_IN_URB; ++i) {

		struct urb *urb = es1->cport_in_urb[i];

		if (!urb)

			break;

		usb_kill_urb(urb);

		usb_free_urb(urb);

		kfree(es1->cport_in_buffer[i]);

		es1->cport_in_buffer[i] = NULL;

	}

	usb_kill_urb(es1->svc_urb);

	usb_free_urb(es1->svc_urb);

	es1->svc_urb = NULL;

	kfree(es1->svc_buffer);

	es1->svc_buffer = NULL;

	usb_set_intfdata(interface, NULL);

	udev = es1->usb_dev;

	greybus_remove_hd(es1->hd);

	usb_put_dev(udev);

}

/* Callback for when we get a SVC message */

static void svc_in_callback(struct urb *urb)

{

	struct greybus_host_device *hd = urb->context;

	struct device *dev = &urb->dev->dev;

	int status = check_urb_status(urb);

	int retval;

	if (status) {

		if ((status == -EAGAIN) || (status == -EPROTO))

			goto exit;

		dev_err(dev, "urb svc in error %d (dropped)\n", status);

		return;

	}

	/* We have a message, create a new message structure, add it to the

	 * list, and wake up our thread that will process the messages.

	 */

	greybus_svc_in(hd, urb->transfer_buffer, urb->actual_length);

exit:

	/* resubmit the urb to get more messages */

	retval = usb_submit_urb(urb, GFP_ATOMIC);

	if (retval)

		dev_err(dev, "Can not submit urb for AP data: %d\n", retval);

}

static void cport_in_callback(struct urb *urb)

{

	struct greybus_host_device *hd = urb->context;

	struct device *dev = &urb->dev->dev;

	int status = check_urb_status(urb);

	int retval;

	u16 cport_id;

	u8 *data;

	if (status) {

		if ((status == -EAGAIN) || (status == -EPROTO))

			goto exit;

		dev_err(dev, "urb cport in error %d (dropped)\n", status);

		return;

	}

	/* The size has to be at least one, for the cport id */

	if (!urb->actual_length) {

		dev_err(dev, "%s: no cport id in input buffer?\n", __func__);

		goto exit;

	}

	/*

	 * Our CPort number is the first byte of the data stream,

	 * the rest of the stream is "real" data

	 */

	data = urb->transfer_buffer;

	cport_id = (u16)data[0];

	data = &data[1];

	/* Pass this data to the greybus core */

	greybus_data_rcvd(hd, cport_id, data, urb->actual_length - 1);

exit:

	/* put our urb back in the request pool */

	retval = usb_submit_urb(urb, GFP_ATOMIC);

	if (retval)

		dev_err(dev, "%s: error %d in submitting urb.\n",

			__func__, retval);

}

static void cport_out_callback(struct urb *urb)

{

	struct greybus_host_device *hd = urb->context;

	struct es1_ap_dev *es1 = hd_to_es1(hd);

	int status = check_urb_status(urb);

	u8 *data = urb->transfer_buffer + 1;

	/*

	 * Tell the submitter that the buffer send (attempt) is

	 * complete, and report the status.  The submitter's buffer

	 * starts after the one-byte CPort id we inserted.

	 */

	data = urb->transfer_buffer + 1;

	greybus_data_sent(hd, data, status);

	free_urb(es1, urb);

	/*

	 * Rest assured Greg, this craziness is getting fixed.

	 *

	 * Yes, you are right, we aren't telling anyone that the urb finished.

	 * "That's crazy!  How does this all even work?" you might be saying.

	 * The "magic" is the idea that greybus works on the "operation" level,

	 * not the "send a buffer" level.  All operations are "round-trip" with

	 * a response from the device that the operation finished, or it will

	 * time out.  Because of that, we don't care that this urb finished, or

	 * failed, or did anything else, as higher levels of the protocol stack

	 * will handle completions and timeouts and the rest.

	 *

	 * This protocol is "needed" due to some hardware restrictions on the

	 * current generation of Unipro controllers.  Think about it for a

	 * minute, this is a USB driver, talking to a Unipro bridge, impedance

	 * mismatch is huge, yet the Unipro controller are even more

	 * underpowered than this little USB controller.  We rely on the round

	 * trip to keep stalls in the Unipro controllers from happening so that

	 * we can keep data flowing properly, no matter how slow it might be.

	 *

	 * Once again, a wonderful bus protocol cut down in its prime by a naive

	 * controller chip.  We dream of the day we have a "real" HCD for

	 * Unipro.  Until then, we suck it up and make the hardware work, as

	 * that's the job of the firmware and kernel.

	 * </rant>

	 */

}

/*

 * The ES1 USB Bridge device contains 4 endpoints

 * 1 Control - usual USB stuff + AP -> SVC messages

 * 1 Interrupt IN - SVC -> AP messages

 * 1 Bulk IN - CPort data in

 * 1 Bulk OUT - CPort data out

 */

static int ap_probe(struct usb_interface *interface,

		    const struct usb_device_id *id)

{

	struct es1_ap_dev *es1;

	struct greybus_host_device *hd;

	struct usb_device *udev;

	struct usb_host_interface *iface_desc;

	struct usb_endpoint_descriptor *endpoint;

	bool int_in_found = false;

	bool bulk_in_found = false;

	bool bulk_out_found = false;

	int retval = -ENOMEM;

	int i;

	u8 svc_interval = 0;

	udev = usb_get_dev(interface_to_usbdev(interface));

	hd = greybus_create_hd(&es1_driver, &udev->dev);

	if (!hd) {

		usb_put_dev(udev);

		return -ENOMEM;

	}

	/* Fill in the buffer allocation constraints */

	hd_buffer_constraints(hd);

	es1 = hd_to_es1(hd);

	es1->hd = hd;

	es1->usb_intf = interface;

	es1->usb_dev = udev;

	spin_lock_init(&es1->cport_out_urb_lock);

	usb_set_intfdata(interface, es1);

	/* Control endpoint is the pipe to talk to this AP, so save it off */

	endpoint = &udev->ep0.desc;

	es1->control_endpoint = endpoint->bEndpointAddress;

	/* find all 3 of our endpoints */

	iface_desc = interface->cur_altsetting;

	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {

		endpoint = &iface_desc->endpoint[i].desc;

		if (usb_endpoint_is_int_in(endpoint)) {

			es1->svc_endpoint = endpoint->bEndpointAddress;

			svc_interval = endpoint->bInterval;

			int_in_found = true;

		} else if (usb_endpoint_is_bulk_in(endpoint)) {

			es1->cport_in_endpoint = endpoint->bEndpointAddress;

			bulk_in_found = true;

		} else if (usb_endpoint_is_bulk_out(endpoint)) {

			es1->cport_out_endpoint = endpoint->bEndpointAddress;

			bulk_out_found = true;

		} else {

			dev_err(&udev->dev,

				"Unknown endpoint type found, address %x\n",

				endpoint->bEndpointAddress);

		}

	}

	if ((int_in_found == false) ||

	    (bulk_in_found == false) ||

	    (bulk_out_found == false)) {

		dev_err(&udev->dev, "Not enough endpoints found in device, aborting!\n");

		goto error;

	}

	/* Create our buffer and URB to get SVC messages, and start it up */

	es1->svc_buffer = kmalloc(ES1_SVC_MSG_SIZE, GFP_KERNEL);

	if (!es1->svc_buffer)

		goto error;

	es1->svc_urb = usb_alloc_urb(0, GFP_KERNEL);

	if (!es1->svc_urb)

		goto error;

	usb_fill_int_urb(es1->svc_urb, udev,

			 usb_rcvintpipe(udev, es1->svc_endpoint),

			 es1->svc_buffer, ES1_SVC_MSG_SIZE, svc_in_callback,

			 hd, svc_interval);

	retval = usb_submit_urb(es1->svc_urb, GFP_KERNEL);

	if (retval)

		goto error;

	/* Allocate buffers for our cport in messages and start them up */

	for (i = 0; i < NUM_CPORT_IN_URB; ++i) {

		struct urb *urb;

		u8 *buffer;

		urb = usb_alloc_urb(0, GFP_KERNEL);

		if (!urb)

			goto error;

		buffer = kmalloc(ES1_GBUF_MSG_SIZE_MAX, GFP_KERNEL);

		if (!buffer)

			goto error;

		usb_fill_bulk_urb(urb, udev,

				  usb_rcvbulkpipe(udev, es1->cport_in_endpoint),

				  buffer, ES1_GBUF_MSG_SIZE_MAX,

				  cport_in_callback, hd);

		es1->cport_in_urb[i] = urb;

		es1->cport_in_buffer[i] = buffer;

		retval = usb_submit_urb(urb, GFP_KERNEL);

		if (retval)

			goto error;

	}

	/* Allocate urbs for our CPort OUT messages */

	for (i = 0; i < NUM_CPORT_OUT_URB; ++i) {

		struct urb *urb;

		urb = usb_alloc_urb(0, GFP_KERNEL);

		if (!urb)

			goto error;

		es1->cport_out_urb[i] = urb;

		es1->cport_out_urb_busy[i] = false;	/* just to be anal */

	}

	return 0;

error:

	ap_disconnect(interface);

	return retval;

}

static struct usb_driver es1_ap_driver = {

	.name =		"es1_ap_driver",

	.probe =	ap_probe,

	.disconnect =	ap_disconnect,

	.id_table =	id_table,

};

module_usb_driver(es1_ap_driver);

MODULE_LICENSE("GPL");

MODULE_AUTHOR("Greg Kroah-Hartman <gregkh@linuxfoundation.org>");