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linux/drivers/usb/gadget/f_serial.c
Sebastian Andrzej Siewior 19b10a8828 usb: gadget: allocate & giveback serial ports instead hard code them 
This patch removes gserial_setup() and gserial_cleanup() and adds
gserial_alloc_line() and gserial_free_line() to replace them.

The initial setup of u_serial happens now on module load time. A
maximum of four TTY ports can be requested which is the current limit.
In theory we could extend this limit, the hard limit is the number of
available endpoints.
alloc_tty_driver() is now called at module init time with the max
available ports. The per-line footprint here is on 32bit is 3 * size of
pointer + 60 bytes (for cdevs).
The remaining memory (struct gs_port) is allocated once a port is
requested.

With this change it is possible to load g_multi and g_serial at the same
time. GS0 receives the module that is loaded first, GS1 is received by
the next module and so on. With the configfs interface the port number
can be exported and the device node is more predictable. Nothing changes
for g_serial and friends as long as one module is used.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>
2013-01-21 20:52:43 +02:00

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/*
* 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/slab.h>
#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 f_gser {
struct gserial port;
u8 data_id;
u8 port_num;
};
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 = 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 = 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,
};
static struct usb_endpoint_descriptor gser_ss_in_desc __initdata = {
.bLength = USB_DT_ENDPOINT_SIZE,
.bDescriptorType = USB_DT_ENDPOINT,
.bmAttributes = USB_ENDPOINT_XFER_BULK,
.wMaxPacketSize = cpu_to_le16(1024),
};
static struct usb_endpoint_descriptor gser_ss_out_desc __initdata = {
.bLength = USB_DT_ENDPOINT_SIZE,
.bDescriptorType = USB_DT_ENDPOINT,
.bmAttributes = USB_ENDPOINT_XFER_BULK,
.wMaxPacketSize = cpu_to_le16(1024),
};
static struct usb_ss_ep_comp_descriptor gser_ss_bulk_comp_desc __initdata = {
.bLength = sizeof gser_ss_bulk_comp_desc,
.bDescriptorType = USB_DT_SS_ENDPOINT_COMP,
};
static struct usb_descriptor_header *gser_ss_function[] __initdata = {
(struct usb_descriptor_header *) &gser_interface_desc,
(struct usb_descriptor_header *) &gser_ss_in_desc,
(struct usb_descriptor_header *) &gser_ss_bulk_comp_desc,
(struct usb_descriptor_header *) &gser_ss_out_desc,
(struct usb_descriptor_header *) &gser_ss_bulk_comp_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);
}
if (!gser->port.in->desc || !gser->port.out->desc) {
DBG(cdev, "activate generic ttyGS%d\n", gser->port_num);
if (config_ep_by_speed(cdev->gadget, f, gser->port.in) ||
config_ep_by_speed(cdev->gadget, f, gser->port.out)) {
gser->port.in->desc = NULL;
gser->port.out->desc = NULL;
return -EINVAL;
}
}
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 */
/* support all relevant hardware speeds... we expect that when
* hardware is dual speed, all bulk-capable endpoints work at
* both speeds
*/
gser_hs_in_desc.bEndpointAddress = gser_fs_in_desc.bEndpointAddress;
gser_hs_out_desc.bEndpointAddress = gser_fs_out_desc.bEndpointAddress;
gser_ss_in_desc.bEndpointAddress = gser_fs_in_desc.bEndpointAddress;
gser_ss_out_desc.bEndpointAddress = gser_fs_out_desc.bEndpointAddress;
status = usb_assign_descriptors(f, gser_fs_function, gser_hs_function,
gser_ss_function);
if (status)
goto fail;
DBG(cdev, "generic ttyGS%d: %s speed IN/%s OUT/%s\n",
gser->port_num,
gadget_is_superspeed(c->cdev->gadget) ? "super" :
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)
{
usb_free_all_descriptors(f);
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.
*/
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;
}
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