usb: gadget: f_printer: convert to new function interface with backward compatibility

In order to add configfs support, a usb function must be converted to use
the new interface. This patch converts the function to the new interface
and provides backward compatiblity layer, which can be removed after
all its users are converted to use the new interface.
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/Kconfig

@@ -196,6 +196,9 @@ config USB_F_MIDI
 config USB_F_HID
 	tristate
 
+config USB_F_PRINTER
+	tristate
+
 choice
 	tristate "USB Gadget Drivers"
 	default USB_ETH

drivers/usb/gadget/function/Makefile

@@ -42,3 +42,5 @@ usb_f_midi-y			:= f_midi.o
 obj-$(CONFIG_USB_F_MIDI)	+= usb_f_midi.o
 usb_f_hid-y			:= f_hid.o
 obj-$(CONFIG_USB_F_HID)		+= usb_f_hid.o
+usb_f_printer-y			:= f_printer.o
+obj-$(CONFIG_USB_F_PRINTER)	+= usb_f_printer.o

drivers/usb/gadget/function/f_printer.c

@@ -24,6 +24,7 @@
 #include <linux/mutex.h>
 #include <linux/errno.h>
 #include <linux/init.h>
+#include <linux/idr.h>
 #include <linux/timer.h>
 #include <linux/list.h>
 #include <linux/interrupt.h>
@@ -46,6 +47,8 @@
 #include <linux/usb/gadget.h>
 #include <linux/usb/g_printer.h>
 
+#include "u_printer.h"
+
 #define PNP_STRING_LEN		1024
 #define PRINTER_MINORS		4
 #define GET_DEVICE_ID		0
@@ -54,6 +57,10 @@
 
 static int major, minors;
 static struct class *usb_gadget_class;
+#ifndef USBF_PRINTER_INCLUDED
+static DEFINE_IDA(printer_ida);
+static DEFINE_MUTEX(printer_ida_lock); /* protects access do printer_ida */
+#endif
 
 /*-------------------------------------------------------------------------*/
 
@@ -999,7 +1006,7 @@ static int printer_func_setup(struct usb_function *f,
 	return value;
 }
 
-static int __init printer_func_bind(struct usb_configuration *c,
+static int printer_func_bind(struct usb_configuration *c,
 		struct usb_function *f)
 {
 	struct usb_gadget *gadget = c->cdev->gadget;
@@ -1111,6 +1118,7 @@ static int __init printer_func_bind(struct usb_configuration *c,
 
 }
 
+#ifdef USBF_PRINTER_INCLUDED
 static void printer_func_unbind(struct usb_configuration *c,
 		struct usb_function *f)
 {
@@ -1155,6 +1163,7 @@ static void printer_func_unbind(struct usb_configuration *c,
 	usb_free_all_descriptors(f);
 	kfree(dev);
 }
+#endif
 
 static int printer_func_set_alt(struct usb_function *f,
 		unsigned intf, unsigned alt)
@@ -1180,6 +1189,7 @@ static void printer_func_disable(struct usb_function *f)
 	spin_unlock_irqrestore(&dev->lock, flags);
 }
 
+#ifdef USBF_PRINTER_INCLUDED
 static int f_printer_bind_config(struct usb_configuration *c, char *pnp_str,
 				 char *pnp_string, unsigned q_len, int minor)
 {
@@ -1240,6 +1250,179 @@ static int f_printer_bind_config(struct usb_configuration *c, char *pnp_str,
 	INFO(dev, "%s, version: " DRIVER_VERSION "\n", driver_desc);
 	return 0;
 }
+#else
+static inline int gprinter_get_minor(void)
+{
+	return ida_simple_get(&printer_ida, 0, 0, GFP_KERNEL);
+}
+
+static inline void gprinter_put_minor(int minor)
+{
+	ida_simple_remove(&printer_ida, minor);
+}
+
+static int gprinter_setup(int);
+static void gprinter_cleanup(void);
+
+static void gprinter_free_inst(struct usb_function_instance *f)
+{
+	struct f_printer_opts *opts;
+
+	opts = container_of(f, struct f_printer_opts, func_inst);
+
+	mutex_lock(&printer_ida_lock);
+
+	gprinter_put_minor(opts->minor);
+	if (idr_is_empty(&printer_ida.idr))
+		gprinter_cleanup();
+
+	mutex_unlock(&printer_ida_lock);
+
+	kfree(opts);
+}
+
+static struct usb_function_instance *gprinter_alloc_inst(void)
+{
+	struct f_printer_opts *opts;
+	struct usb_function_instance *ret;
+	int status = 0;
+
+	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
+	if (!opts)
+		return ERR_PTR(-ENOMEM);
+
+	opts->func_inst.free_func_inst = gprinter_free_inst;
+	ret = &opts->func_inst;
+
+	mutex_lock(&printer_ida_lock);
+
+	if (idr_is_empty(&printer_ida.idr)) {
+		status = gprinter_setup(PRINTER_MINORS);
+		if (status) {
+			ret = ERR_PTR(status);
+			kfree(opts);
+			goto unlock;
+		}
+	}
+
+	opts->minor = gprinter_get_minor();
+	if (opts->minor < 0) {
+		ret = ERR_PTR(opts->minor);
+		kfree(opts);
+		if (idr_is_empty(&printer_ida.idr))
+			gprinter_cleanup();
+	}
+
+unlock:
+	mutex_unlock(&printer_ida_lock);
+	return ret;
+}
+
+static void gprinter_free(struct usb_function *f)
+{
+	struct printer_dev *dev = func_to_printer(f);
+
+	kfree(dev);
+}
+
+static void printer_func_unbind(struct usb_configuration *c,
+		struct usb_function *f)
+{
+	struct printer_dev	*dev;
+	struct usb_request	*req;
+
+	dev = func_to_printer(f);
+
+	device_destroy(usb_gadget_class, MKDEV(major, dev->minor));
+
+	/* Remove Character Device */
+	cdev_del(&dev->printer_cdev);
+
+	/* we must already have been disconnected ... no i/o may be active */
+	WARN_ON(!list_empty(&dev->tx_reqs_active));
+	WARN_ON(!list_empty(&dev->rx_reqs_active));
+
+	/* Free all memory for this driver. */
+	while (!list_empty(&dev->tx_reqs)) {
+		req = container_of(dev->tx_reqs.next, struct usb_request,
+				list);
+		list_del(&req->list);
+		printer_req_free(dev->in_ep, req);
+	}
+
+	if (dev->current_rx_req != NULL)
+		printer_req_free(dev->out_ep, dev->current_rx_req);
+
+	while (!list_empty(&dev->rx_reqs)) {
+		req = container_of(dev->rx_reqs.next,
+				struct usb_request, list);
+		list_del(&req->list);
+		printer_req_free(dev->out_ep, req);
+	}
+
+	while (!list_empty(&dev->rx_buffers)) {
+		req = container_of(dev->rx_buffers.next,
+				struct usb_request, list);
+		list_del(&req->list);
+		printer_req_free(dev->out_ep, req);
+	}
+	usb_free_all_descriptors(f);
+}
+
+static struct usb_function *gprinter_alloc(struct usb_function_instance *fi)
+{
+	struct printer_dev	*dev;
+	struct f_printer_opts	*opts;
+
+	opts = container_of(fi, struct f_printer_opts, func_inst);
+
+	if (opts->minor >= minors)
+		return ERR_PTR(-ENOENT);
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return ERR_PTR(-ENOMEM);
+
+	dev->minor = opts->minor;
+	dev->pnp_string = opts->pnp_string;
+	dev->q_len = opts->q_len;
+
+	dev->function.name = "printer";
+	dev->function.bind = printer_func_bind;
+	dev->function.setup = printer_func_setup;
+	dev->function.unbind = printer_func_unbind;
+	dev->function.set_alt = printer_func_set_alt;
+	dev->function.disable = printer_func_disable;
+	dev->function.req_match = gprinter_req_match;
+	dev->function.free_func = gprinter_free;
+
+	INIT_LIST_HEAD(&dev->tx_reqs);
+	INIT_LIST_HEAD(&dev->rx_reqs);
+	INIT_LIST_HEAD(&dev->rx_buffers);
+	INIT_LIST_HEAD(&dev->tx_reqs_active);
+	INIT_LIST_HEAD(&dev->rx_reqs_active);
+
+	spin_lock_init(&dev->lock);
+	mutex_init(&dev->lock_printer_io);
+	init_waitqueue_head(&dev->rx_wait);
+	init_waitqueue_head(&dev->tx_wait);
+	init_waitqueue_head(&dev->tx_flush_wait);
+
+	dev->interface = -1;
+	dev->printer_cdev_open = 0;
+	dev->printer_status = PRINTER_NOT_ERROR;
+	dev->current_rx_req = NULL;
+	dev->current_rx_bytes = 0;
+	dev->current_rx_buf = NULL;
+
+	return &dev->function;
+}
+
+DECLARE_USB_FUNCTION_INIT(printer, gprinter_alloc_inst, gprinter_alloc);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Craig Nadler");
+
+#endif
 
 static int gprinter_setup(int count)
 {

drivers/usb/gadget/function/u_printer.h

+/*
+ * u_printer.h
+ *
+ * Utility definitions for the printer function
+ *
+ * Copyright (c) 2015 Samsung Electronics Co., Ltd.
+ *		http://www.samsung.com
+ *
+ * Author: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef U_PRINTER_H
+#define U_PRINTER_H
+
+#include <linux/usb/composite.h>
+
+#define PNP_STRING_LEN			1024
+
+struct f_printer_opts {
+	struct usb_function_instance	func_inst;
+	int				minor;
+	char				pnp_string[PNP_STRING_LEN];
+	unsigned			q_len;
+};
+
+#endif /* U_PRINTER_H */

drivers/usb/gadget/legacy/printer.c

@@ -33,6 +33,7 @@ static const char driver_desc [] = DRIVER_DESC;
  * This will be changed when f_printer is converted
  * to the new function interface.
  */
+#define USBF_PRINTER_INCLUDED
 #include "f_printer.c"
 
 /*-------------------------------------------------------------------------*/