usb gadget serial: split out generic serial function

Split out the generic serial support into a "function driver".  This
closely mimics the ACM support, but with a MUCH simpler control model.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 296 insertions, 0 deletions

diff --git a/drivers/usb/gadget/f_serial.c b/drivers/usb/gadget/f_serial.c
new file mode 100644
index 000000000000..1b6bde9aaed5
--- /dev/null
+++ b/drivers/usb/gadget/f_serial.c
@@ -0,0 +1,296 @@
+/*
+ * f_serial.c - generic USB serial function driver
+ *
+ * Copyright (C) 2003 Al Borchers (alborchers@steinerpoint.com)
+ * Copyright (C) 2008 by David Brownell
+ * Copyright (C) 2008 by Nokia Corporation
+ *
+ * This software is distributed under the terms of the GNU General
+ * Public License ("GPL") as published by the Free Software Foundation,
+ * either version 2 of that License or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+
+#include "u_serial.h"
+#include "gadget_chips.h"
+
+
+/*
+ * This function packages a simple "generic serial" port with no real
+ * control mechanisms, just raw data transfer over two bulk endpoints.
+ *
+ * Because it's not standardized, this isn't as interoperable as the
+ * CDC ACM driver.  However, for many purposes it's just as functional
+ * if you can arrange appropriate host side drivers.
+ */
+
+struct gser_descs {
+        struct usb_endpoint_descriptor  *in;
+        struct usb_endpoint_descriptor  *out;
+};
+
+struct f_gser {
+        struct gserial                  port;
+        u8                              data_id;
+        u8                              port_num;
+
+        struct usb_descriptor_header    **fs_function;
+        struct gser_descs               fs;
+        struct usb_descriptor_header    **hs_function;
+        struct gser_descs               hs;
+};
+
+static inline struct f_gser *func_to_gser(struct usb_function *f)
+{
+        return container_of(f, struct f_gser, port.func);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* interface descriptor: */
+
+static struct usb_interface_descriptor gser_interface_desc __initdata = {
+        .bLength =              USB_DT_INTERFACE_SIZE,
+        .bDescriptorType =      USB_DT_INTERFACE,
+        /* .bInterfaceNumber = DYNAMIC */
+        .bNumEndpoints =        2,
+        .bInterfaceClass =      USB_CLASS_VENDOR_SPEC,
+        .bInterfaceSubClass =   0,
+        .bInterfaceProtocol =   0,
+        /* .iInterface = DYNAMIC */
+};
+
+/* full speed support: */
+
+static struct usb_endpoint_descriptor gser_fs_in_desc __initdata = {
+        .bLength =              USB_DT_ENDPOINT_SIZE,
+        .bDescriptorType =      USB_DT_ENDPOINT,
+        .bEndpointAddress =     USB_DIR_IN,
+        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_endpoint_descriptor gser_fs_out_desc __initdata = {
+        .bLength =              USB_DT_ENDPOINT_SIZE,
+        .bDescriptorType =      USB_DT_ENDPOINT,
+        .bEndpointAddress =     USB_DIR_OUT,
+        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
+};
+
+static struct usb_descriptor_header *gser_fs_function[] __initdata = {
+        (struct usb_descriptor_header *) &gser_interface_desc,
+        (struct usb_descriptor_header *) &gser_fs_in_desc,
+        (struct usb_descriptor_header *) &gser_fs_out_desc,
+        NULL,
+};
+
+/* high speed support: */
+
+static struct usb_endpoint_descriptor gser_hs_in_desc __initdata = {
+        .bLength =              USB_DT_ENDPOINT_SIZE,
+        .bDescriptorType =      USB_DT_ENDPOINT,
+        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
+        .wMaxPacketSize =       __constant_cpu_to_le16(512),
+};
+
+static struct usb_endpoint_descriptor gser_hs_out_desc __initdata = {
+        .bLength =              USB_DT_ENDPOINT_SIZE,
+        .bDescriptorType =      USB_DT_ENDPOINT,
+        .bmAttributes =         USB_ENDPOINT_XFER_BULK,
+        .wMaxPacketSize =       __constant_cpu_to_le16(512),
+};
+
+static struct usb_descriptor_header *gser_hs_function[] __initdata = {
+        (struct usb_descriptor_header *) &gser_interface_desc,
+        (struct usb_descriptor_header *) &gser_hs_in_desc,
+        (struct usb_descriptor_header *) &gser_hs_out_desc,
+        NULL,
+};
+
+/* string descriptors: */
+
+static struct usb_string gser_string_defs[] = {
+        [0].s = "Generic Serial",
+        {  } /* end of list */
+};
+
+static struct usb_gadget_strings gser_string_table = {
+        .language =             0x0409, /* en-us */
+        .strings =              gser_string_defs,
+};
+
+static struct usb_gadget_strings *gser_strings[] = {
+        &gser_string_table,
+        NULL,
+};
+
+/*-------------------------------------------------------------------------*/
+
+static int gser_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
+{
+        struct f_gser           *gser = func_to_gser(f);
+        struct usb_composite_dev *cdev = f->config->cdev;
+
+        /* we know alt == 0, so this is an activation or a reset */
+
+        if (gser->port.in->driver_data) {
+                DBG(cdev, "reset generic ttyGS%d\n", gser->port_num);
+                gserial_disconnect(&gser->port);
+        } else {
+                DBG(cdev, "activate generic ttyGS%d\n", gser->port_num);
+                gser->port.in_desc = ep_choose(cdev->gadget,
+                                gser->hs.in, gser->fs.in);
+                gser->port.out_desc = ep_choose(cdev->gadget,
+                                gser->hs.out, gser->fs.out);
+        }
+        gserial_connect(&gser->port, gser->port_num);
+        return 0;
+}
+
+static void gser_disable(struct usb_function *f)
+{
+        struct f_gser   *gser = func_to_gser(f);
+        struct usb_composite_dev *cdev = f->config->cdev;
+
+        DBG(cdev, "generic ttyGS%d deactivated\n", gser->port_num);
+        gserial_disconnect(&gser->port);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* serial function driver setup/binding */
+
+static int __init
+gser_bind(struct usb_configuration *c, struct usb_function *f)
+{
+        struct usb_composite_dev *cdev = c->cdev;
+        struct f_gser           *gser = func_to_gser(f);
+        int                     status;
+        struct usb_ep           *ep;
+
+        /* allocate instance-specific interface IDs */
+        status = usb_interface_id(c, f);
+        if (status < 0)
+                goto fail;
+        gser->data_id = status;
+        gser_interface_desc.bInterfaceNumber = status;
+
+        status = -ENODEV;
+
+        /* allocate instance-specific endpoints */
+        ep = usb_ep_autoconfig(cdev->gadget, &gser_fs_in_desc);
+        if (!ep)
+                goto fail;
+        gser->port.in = ep;
+        ep->driver_data = cdev; /* claim */
+
+        ep = usb_ep_autoconfig(cdev->gadget, &gser_fs_out_desc);
+        if (!ep)
+                goto fail;
+        gser->port.out = ep;
+        ep->driver_data = cdev; /* claim */
+
+        /* copy descriptors, and track endpoint copies */
+        f->descriptors = usb_copy_descriptors(gser_fs_function);
+
+        gser->fs.in = usb_find_endpoint(gser_fs_function,
+                        f->descriptors, &gser_fs_in_desc);
+        gser->fs.out = usb_find_endpoint(gser_fs_function,
+                        f->descriptors, &gser_fs_out_desc);
+
+
+        /* support all relevant hardware speeds... we expect that when
+         * hardware is dual speed, all bulk-capable endpoints work at
+         * both speeds
+         */
+        if (gadget_is_dualspeed(c->cdev->gadget)) {
+                gser_hs_in_desc.bEndpointAddress =
+                                gser_fs_in_desc.bEndpointAddress;
+                gser_hs_out_desc.bEndpointAddress =
+                                gser_fs_out_desc.bEndpointAddress;
+
+                /* copy descriptors, and track endpoint copies */
+                f->hs_descriptors = usb_copy_descriptors(gser_hs_function);
+
+                gser->hs.in = usb_find_endpoint(gser_hs_function,
+                                f->hs_descriptors, &gser_hs_in_desc);
+                gser->hs.out = usb_find_endpoint(gser_hs_function,
+                                f->hs_descriptors, &gser_hs_out_desc);
+        }
+
+        DBG(cdev, "generic ttyGS%d: %s speed IN/%s OUT/%s\n",
+                        gser->port_num,
+                        gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
+                        gser->port.in->name, gser->port.out->name);
+        return 0;
+
+fail:
+        /* we might as well release our claims on endpoints */
+        if (gser->port.out)
+                gser->port.out->driver_data = NULL;
+        if (gser->port.in)
+                gser->port.in->driver_data = NULL;
+
+        ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
+
+        return status;
+}
+
+static void
+gser_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+        if (gadget_is_dualspeed(c->cdev->gadget))
+                usb_free_descriptors(f->hs_descriptors);
+        usb_free_descriptors(f->descriptors);
+        kfree(func_to_gser(f));
+}
+
+/**
+ * gser_bind_config - add a generic serial function to a configuration
+ * @c: the configuration to support the serial instance
+ * @port_num: /dev/ttyGS* port this interface will use
+ * Context: single threaded during gadget setup
+ *
+ * Returns zero on success, else negative errno.
+ *
+ * Caller must have called @gserial_setup() with enough ports to
+ * handle all the ones it binds.  Caller is also responsible
+ * for calling @gserial_cleanup() before module unload.
+ */
+int __init gser_bind_config(struct usb_configuration *c, u8 port_num)
+{
+        struct f_gser   *gser;
+        int             status;
+
+        /* REVISIT might want instance-specific strings to help
+         * distinguish instances ...
+         */
+
+        /* maybe allocate device-global string ID */
+        if (gser_string_defs[0].id == 0) {
+                status = usb_string_id(c->cdev);
+                if (status < 0)
+                        return status;
+                gser_string_defs[0].id = status;
+        }
+
+        /* allocate and initialize one new instance */
+        gser = kzalloc(sizeof *gser, GFP_KERNEL);
+        if (!gser)
+                return -ENOMEM;
+
+        gser->port_num = port_num;
+
+        gser->port.func.name = "gser";
+        gser->port.func.strings = gser_strings;
+        gser->port.func.bind = gser_bind;
+        gser->port.func.unbind = gser_unbind;
+        gser->port.func.set_alt = gser_set_alt;
+        gser->port.func.disable = gser_disable;
+
+        status = usb_add_function(c, &gser->port.func);
+        if (status)
+                kfree(gser);
+        return status;
+}