usb gadget serial: split out CDC ACM function
Split out CDC ACM parts of "gadget serial" to a "function driver".
Some key structural differences from the previous ACM support, shared
with with the generic serial function (next patch):
- As a function driver, it can be combined with other functions.
One gadget configuration could offer both serial and network
links, as an example.
- One serial port can be exposed in multiple configurations;
the /dev/ttyGS0 node could be exposed regardless of which
config the host selected.
- One configuration can expose multiple serial ports, such as
ttyGS0, ttyGS1, ttyGS2, and ttyGS3.
This code should be a lot easier to understand than the previous
all-in-one-big-file version of the driver.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/gadget/f_acm.c b/drivers/usb/gadget/f_acm.c
new file mode 100644
index 0000000..d8faccf
--- /dev/null
+++ b/drivers/usb/gadget/f_acm.c
@@ -0,0 +1,589 @@
+/*
+ * f_acm.c -- USB CDC serial (ACM) 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.
+ */
+
+/* #define VERBOSE_DEBUG */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+
+#include "u_serial.h"
+#include "gadget_chips.h"
+
+
+/*
+ * This CDC ACM function support just wraps control functions and
+ * notifications around the generic serial-over-usb code.
+ *
+ * Because CDC ACM is standardized by the USB-IF, many host operating
+ * systems have drivers for it. Accordingly, ACM is the preferred
+ * interop solution for serial-port type connections. The control
+ * models are often not necessary, and in any case don't do much in
+ * this bare-bones implementation.
+ *
+ * Note that even MS-Windows has some support for ACM. However, that
+ * support is somewhat broken because when you use ACM in a composite
+ * device, having multiple interfaces confuses the poor OS. It doesn't
+ * seem to understand CDC Union descriptors. The new "association"
+ * descriptors (roughly equivalent to CDC Unions) may sometimes help.
+ */
+
+struct acm_ep_descs {
+ struct usb_endpoint_descriptor *in;
+ struct usb_endpoint_descriptor *out;
+ struct usb_endpoint_descriptor *notify;
+};
+
+struct f_acm {
+ struct gserial port;
+ u8 ctrl_id, data_id;
+ u8 port_num;
+
+ struct usb_descriptor_header **fs_function;
+ struct acm_ep_descs fs;
+ struct usb_descriptor_header **hs_function;
+ struct acm_ep_descs hs;
+
+ struct usb_ep *notify;
+ struct usb_endpoint_descriptor *notify_desc;
+
+ struct usb_cdc_line_coding port_line_coding; /* 8-N-1 etc */
+ u16 port_handshake_bits;
+#define RS232_RTS (1 << 1) /* unused with full duplex */
+#define RS232_DTR (1 << 0) /* host is ready for data r/w */
+};
+
+static inline struct f_acm *func_to_acm(struct usb_function *f)
+{
+ return container_of(f, struct f_acm, port.func);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* notification endpoint uses smallish and infrequent fixed-size messages */
+
+#define GS_LOG2_NOTIFY_INTERVAL 5 /* 1 << 5 == 32 msec */
+#define GS_NOTIFY_MAXPACKET 8
+
+/* interface and class descriptors: */
+
+static struct usb_interface_descriptor acm_control_interface_desc __initdata = {
+ .bLength = USB_DT_INTERFACE_SIZE,
+ .bDescriptorType = USB_DT_INTERFACE,
+ /* .bInterfaceNumber = DYNAMIC */
+ .bNumEndpoints = 1,
+ .bInterfaceClass = USB_CLASS_COMM,
+ .bInterfaceSubClass = USB_CDC_SUBCLASS_ACM,
+ .bInterfaceProtocol = USB_CDC_ACM_PROTO_AT_V25TER,
+ /* .iInterface = DYNAMIC */
+};
+
+static struct usb_interface_descriptor acm_data_interface_desc __initdata = {
+ .bLength = USB_DT_INTERFACE_SIZE,
+ .bDescriptorType = USB_DT_INTERFACE,
+ /* .bInterfaceNumber = DYNAMIC */
+ .bNumEndpoints = 2,
+ .bInterfaceClass = USB_CLASS_CDC_DATA,
+ .bInterfaceSubClass = 0,
+ .bInterfaceProtocol = 0,
+ /* .iInterface = DYNAMIC */
+};
+
+static struct usb_cdc_header_desc acm_header_desc __initdata = {
+ .bLength = sizeof(acm_header_desc),
+ .bDescriptorType = USB_DT_CS_INTERFACE,
+ .bDescriptorSubType = USB_CDC_HEADER_TYPE,
+ .bcdCDC = __constant_cpu_to_le16(0x0110),
+};
+
+static struct usb_cdc_call_mgmt_descriptor
+acm_call_mgmt_descriptor __initdata = {
+ .bLength = sizeof(acm_call_mgmt_descriptor),
+ .bDescriptorType = USB_DT_CS_INTERFACE,
+ .bDescriptorSubType = USB_CDC_CALL_MANAGEMENT_TYPE,
+ .bmCapabilities = 0,
+ /* .bDataInterface = DYNAMIC */
+};
+
+static struct usb_cdc_acm_descriptor acm_descriptor __initdata = {
+ .bLength = sizeof(acm_descriptor),
+ .bDescriptorType = USB_DT_CS_INTERFACE,
+ .bDescriptorSubType = USB_CDC_ACM_TYPE,
+ .bmCapabilities = (1 << 1),
+};
+
+static struct usb_cdc_union_desc acm_union_desc __initdata = {
+ .bLength = sizeof(acm_union_desc),
+ .bDescriptorType = USB_DT_CS_INTERFACE,
+ .bDescriptorSubType = USB_CDC_UNION_TYPE,
+ /* .bMasterInterface0 = DYNAMIC */
+ /* .bSlaveInterface0 = DYNAMIC */
+};
+
+/* full speed support: */
+
+static struct usb_endpoint_descriptor acm_fs_notify_desc __initdata = {
+ .bLength = USB_DT_ENDPOINT_SIZE,
+ .bDescriptorType = USB_DT_ENDPOINT,
+ .bEndpointAddress = USB_DIR_IN,
+ .bmAttributes = USB_ENDPOINT_XFER_INT,
+ .wMaxPacketSize = __constant_cpu_to_le16(GS_NOTIFY_MAXPACKET),
+ .bInterval = 1 << GS_LOG2_NOTIFY_INTERVAL,
+};
+
+static struct usb_endpoint_descriptor acm_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 acm_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 *acm_fs_function[] __initdata = {
+ (struct usb_descriptor_header *) &acm_control_interface_desc,
+ (struct usb_descriptor_header *) &acm_header_desc,
+ (struct usb_descriptor_header *) &acm_call_mgmt_descriptor,
+ (struct usb_descriptor_header *) &acm_descriptor,
+ (struct usb_descriptor_header *) &acm_union_desc,
+ (struct usb_descriptor_header *) &acm_fs_notify_desc,
+ (struct usb_descriptor_header *) &acm_data_interface_desc,
+ (struct usb_descriptor_header *) &acm_fs_in_desc,
+ (struct usb_descriptor_header *) &acm_fs_out_desc,
+ NULL,
+};
+
+/* high speed support: */
+
+static struct usb_endpoint_descriptor acm_hs_notify_desc __initdata = {
+ .bLength = USB_DT_ENDPOINT_SIZE,
+ .bDescriptorType = USB_DT_ENDPOINT,
+ .bEndpointAddress = USB_DIR_IN,
+ .bmAttributes = USB_ENDPOINT_XFER_INT,
+ .wMaxPacketSize = __constant_cpu_to_le16(GS_NOTIFY_MAXPACKET),
+ .bInterval = GS_LOG2_NOTIFY_INTERVAL+4,
+};
+
+static struct usb_endpoint_descriptor acm_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 acm_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 *acm_hs_function[] __initdata = {
+ (struct usb_descriptor_header *) &acm_control_interface_desc,
+ (struct usb_descriptor_header *) &acm_header_desc,
+ (struct usb_descriptor_header *) &acm_call_mgmt_descriptor,
+ (struct usb_descriptor_header *) &acm_descriptor,
+ (struct usb_descriptor_header *) &acm_union_desc,
+ (struct usb_descriptor_header *) &acm_hs_notify_desc,
+ (struct usb_descriptor_header *) &acm_data_interface_desc,
+ (struct usb_descriptor_header *) &acm_hs_in_desc,
+ (struct usb_descriptor_header *) &acm_hs_out_desc,
+ NULL,
+};
+
+/* string descriptors: */
+
+#define ACM_CTRL_IDX 0
+#define ACM_DATA_IDX 1
+
+/* static strings, in UTF-8 */
+static struct usb_string acm_string_defs[] = {
+ [ACM_CTRL_IDX].s = "CDC Abstract Control Model (ACM)",
+ [ACM_DATA_IDX].s = "CDC ACM Data",
+ { /* ZEROES END LIST */ },
+};
+
+static struct usb_gadget_strings acm_string_table = {
+ .language = 0x0409, /* en-us */
+ .strings = acm_string_defs,
+};
+
+static struct usb_gadget_strings *acm_strings[] = {
+ &acm_string_table,
+ NULL,
+};
+
+/*-------------------------------------------------------------------------*/
+
+/* ACM control ... data handling is delegated to tty library code.
+ * The main task of this function is to activate and deactivate
+ * that code based on device state; track parameters like line
+ * speed, handshake state, and so on; and issue notifications.
+ */
+
+static void acm_complete_set_line_coding(struct usb_ep *ep,
+ struct usb_request *req)
+{
+ struct f_acm *acm = ep->driver_data;
+ struct usb_composite_dev *cdev = acm->port.func.config->cdev;
+
+ if (req->status != 0) {
+ DBG(cdev, "acm ttyGS%d completion, err %d\n",
+ acm->port_num, req->status);
+ return;
+ }
+
+ /* normal completion */
+ if (req->actual != sizeof(acm->port_line_coding)) {
+ DBG(cdev, "acm ttyGS%d short resp, len %d\n",
+ acm->port_num, req->actual);
+ usb_ep_set_halt(ep);
+ } else {
+ struct usb_cdc_line_coding *value = req->buf;
+
+ /* REVISIT: we currently just remember this data.
+ * If we change that, (a) validate it first, then
+ * (b) update whatever hardware needs updating,
+ * (c) worry about locking. This is information on
+ * the order of 9600-8-N-1 ... most of which means
+ * nothing unless we control a real RS232 line.
+ */
+ acm->port_line_coding = *value;
+ }
+}
+
+static int acm_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
+{
+ struct f_acm *acm = func_to_acm(f);
+ struct usb_composite_dev *cdev = f->config->cdev;
+ struct usb_request *req = cdev->req;
+ int value = -EOPNOTSUPP;
+ u16 w_index = le16_to_cpu(ctrl->wIndex);
+ u16 w_value = le16_to_cpu(ctrl->wValue);
+ u16 w_length = le16_to_cpu(ctrl->wLength);
+
+ /* composite driver infrastructure handles everything except
+ * CDC class messages; interface activation uses set_alt().
+ */
+ switch ((ctrl->bRequestType << 8) | ctrl->bRequest) {
+
+ /* SET_LINE_CODING ... just read and save what the host sends */
+ case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
+ | USB_CDC_REQ_SET_LINE_CODING:
+ if (w_length != sizeof(struct usb_cdc_line_coding)
+ || w_index != acm->ctrl_id)
+ goto invalid;
+
+ value = w_length;
+ cdev->gadget->ep0->driver_data = acm;
+ req->complete = acm_complete_set_line_coding;
+ break;
+
+ /* GET_LINE_CODING ... return what host sent, or initial value */
+ case ((USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
+ | USB_CDC_REQ_GET_LINE_CODING:
+ if (w_index != acm->ctrl_id)
+ goto invalid;
+
+ value = min_t(unsigned, w_length,
+ sizeof(struct usb_cdc_line_coding));
+ memcpy(req->buf, &acm->port_line_coding, value);
+ break;
+
+ /* SET_CONTROL_LINE_STATE ... save what the host sent */
+ case ((USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE) << 8)
+ | USB_CDC_REQ_SET_CONTROL_LINE_STATE:
+ if (w_index != acm->ctrl_id)
+ goto invalid;
+
+ value = 0;
+
+ /* FIXME we should not allow data to flow until the
+ * host sets the RS232_DTR bit; and when it clears
+ * that bit, we should return to that no-flow state.
+ */
+ acm->port_handshake_bits = w_value;
+ break;
+
+ default:
+invalid:
+ VDBG(cdev, "invalid control req%02x.%02x v%04x i%04x l%d\n",
+ ctrl->bRequestType, ctrl->bRequest,
+ w_value, w_index, w_length);
+ }
+
+ /* respond with data transfer or status phase? */
+ if (value >= 0) {
+ DBG(cdev, "acm ttyGS%d req%02x.%02x v%04x i%04x l%d\n",
+ acm->port_num, ctrl->bRequestType, ctrl->bRequest,
+ w_value, w_index, w_length);
+ req->zero = 0;
+ req->length = value;
+ value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
+ if (value < 0)
+ ERROR(cdev, "acm response on ttyGS%d, err %d\n",
+ acm->port_num, value);
+ }
+
+ /* device either stalls (value < 0) or reports success */
+ return value;
+}
+
+static int acm_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
+{
+ struct f_acm *acm = func_to_acm(f);
+ struct usb_composite_dev *cdev = f->config->cdev;
+
+ /* we know alt == 0, so this is an activation or a reset */
+
+ if (intf == acm->ctrl_id) {
+ /* REVISIT this may need more work when we start to
+ * send notifications ...
+ */
+ if (acm->notify->driver_data) {
+ VDBG(cdev, "reset acm control interface %d\n", intf);
+ usb_ep_disable(acm->notify);
+ } else {
+ VDBG(cdev, "init acm ctrl interface %d\n", intf);
+ acm->notify_desc = ep_choose(cdev->gadget,
+ acm->hs.notify,
+ acm->fs.notify);
+ }
+ usb_ep_enable(acm->notify, acm->notify_desc);
+ acm->notify->driver_data = acm;
+
+ } else if (intf == acm->data_id) {
+ if (acm->port.in->driver_data) {
+ DBG(cdev, "reset acm ttyGS%d\n", acm->port_num);
+ gserial_disconnect(&acm->port);
+ } else {
+ DBG(cdev, "activate acm ttyGS%d\n", acm->port_num);
+ acm->port.in_desc = ep_choose(cdev->gadget,
+ acm->hs.in, acm->fs.in);
+ acm->port.out_desc = ep_choose(cdev->gadget,
+ acm->hs.out, acm->fs.out);
+ }
+ gserial_connect(&acm->port, acm->port_num);
+
+ } else
+ return -EINVAL;
+
+ return 0;
+}
+
+static void acm_disable(struct usb_function *f)
+{
+ struct f_acm *acm = func_to_acm(f);
+ struct usb_composite_dev *cdev = f->config->cdev;
+
+ DBG(cdev, "acm ttyGS%d deactivated\n", acm->port_num);
+ gserial_disconnect(&acm->port);
+ usb_ep_disable(acm->notify);
+ acm->notify->driver_data = NULL;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* ACM function driver setup/binding */
+static int __init
+acm_bind(struct usb_configuration *c, struct usb_function *f)
+{
+ struct usb_composite_dev *cdev = c->cdev;
+ struct f_acm *acm = func_to_acm(f);
+ int status;
+ struct usb_ep *ep;
+
+ /* allocate instance-specific interface IDs, and patch descriptors */
+ status = usb_interface_id(c, f);
+ if (status < 0)
+ goto fail;
+ acm->ctrl_id = status;
+
+ acm_control_interface_desc.bInterfaceNumber = status;
+ acm_union_desc .bMasterInterface0 = status;
+
+ status = usb_interface_id(c, f);
+ if (status < 0)
+ goto fail;
+ acm->data_id = status;
+
+ acm_data_interface_desc.bInterfaceNumber = status;
+ acm_union_desc.bSlaveInterface0 = status;
+ acm_call_mgmt_descriptor.bDataInterface = status;
+
+ status = -ENODEV;
+
+ /* allocate instance-specific endpoints */
+ ep = usb_ep_autoconfig(cdev->gadget, &acm_fs_in_desc);
+ if (!ep)
+ goto fail;
+ acm->port.in = ep;
+ ep->driver_data = cdev; /* claim */
+
+ ep = usb_ep_autoconfig(cdev->gadget, &acm_fs_out_desc);
+ if (!ep)
+ goto fail;
+ acm->port.out = ep;
+ ep->driver_data = cdev; /* claim */
+
+ ep = usb_ep_autoconfig(cdev->gadget, &acm_fs_notify_desc);
+ if (!ep)
+ goto fail;
+ acm->notify = ep;
+ ep->driver_data = cdev; /* claim */
+
+ /* copy descriptors, and track endpoint copies */
+ f->descriptors = usb_copy_descriptors(acm_fs_function);
+
+ acm->fs.in = usb_find_endpoint(acm_fs_function,
+ f->descriptors, &acm_fs_in_desc);
+ acm->fs.out = usb_find_endpoint(acm_fs_function,
+ f->descriptors, &acm_fs_out_desc);
+ acm->fs.notify = usb_find_endpoint(acm_fs_function,
+ f->descriptors, &acm_fs_notify_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)) {
+ acm_hs_in_desc.bEndpointAddress =
+ acm_fs_in_desc.bEndpointAddress;
+ acm_hs_out_desc.bEndpointAddress =
+ acm_fs_out_desc.bEndpointAddress;
+ acm_hs_notify_desc.bEndpointAddress =
+ acm_fs_notify_desc.bEndpointAddress;
+
+ /* copy descriptors, and track endpoint copies */
+ f->hs_descriptors = usb_copy_descriptors(acm_hs_function);
+
+ acm->hs.in = usb_find_endpoint(acm_hs_function,
+ f->hs_descriptors, &acm_hs_in_desc);
+ acm->hs.out = usb_find_endpoint(acm_hs_function,
+ f->hs_descriptors, &acm_hs_out_desc);
+ acm->hs.notify = usb_find_endpoint(acm_hs_function,
+ f->hs_descriptors, &acm_hs_notify_desc);
+ }
+
+ /* FIXME provide a callback for triggering notifications */
+
+ DBG(cdev, "acm ttyGS%d: %s speed IN/%s OUT/%s NOTIFY/%s\n",
+ acm->port_num,
+ gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
+ acm->port.in->name, acm->port.out->name,
+ acm->notify->name);
+ return 0;
+
+fail:
+ /* we might as well release our claims on endpoints */
+ if (acm->notify)
+ acm->notify->driver_data = NULL;
+ if (acm->port.out)
+ acm->port.out->driver_data = NULL;
+ if (acm->port.in)
+ acm->port.in->driver_data = NULL;
+
+ ERROR(cdev, "%s/%p: can't bind, err %d\n", f->name, f, status);
+
+ return status;
+}
+
+static void
+acm_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_acm(f));
+}
+
+/* Some controllers can't support CDC ACM ... */
+static inline bool can_support_cdc(struct usb_configuration *c)
+{
+ /* SH3 doesn't support multiple interfaces */
+ if (gadget_is_sh(c->cdev->gadget))
+ return false;
+
+ /* sa1100 doesn't have a third interrupt endpoint */
+ if (gadget_is_sa1100(c->cdev->gadget))
+ return false;
+
+ /* everything else is *probably* fine ... */
+ return true;
+}
+
+/**
+ * acm_bind_config - add a CDC ACM function to a configuration
+ * @c: the configuration to support the CDC ACM 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 acm_bind_config(struct usb_configuration *c, u8 port_num)
+{
+ struct f_acm *acm;
+ int status;
+
+ if (!can_support_cdc(c))
+ return -EINVAL;
+
+ /* REVISIT might want instance-specific strings to help
+ * distinguish instances ...
+ */
+
+ /* maybe allocate device-global string IDs, and patch descriptors */
+ if (acm_string_defs[ACM_CTRL_IDX].id == 0) {
+ status = usb_string_id(c->cdev);
+ if (status < 0)
+ return status;
+ acm_string_defs[ACM_CTRL_IDX].id = status;
+
+ acm_control_interface_desc.iInterface = status;
+
+ status = usb_string_id(c->cdev);
+ if (status < 0)
+ return status;
+ acm_string_defs[ACM_DATA_IDX].id = status;
+
+ acm_data_interface_desc.iInterface = status;
+ }
+
+ /* allocate and initialize one new instance */
+ acm = kzalloc(sizeof *acm, GFP_KERNEL);
+ if (!acm)
+ return -ENOMEM;
+
+ acm->port_num = port_num;
+
+ acm->port.func.name = "acm";
+ acm->port.func.strings = acm_strings;
+ /* descriptors are per-instance copies */
+ acm->port.func.bind = acm_bind;
+ acm->port.func.unbind = acm_unbind;
+ acm->port.func.set_alt = acm_set_alt;
+ acm->port.func.setup = acm_setup;
+ acm->port.func.disable = acm_disable;
+
+ status = usb_add_function(c, &acm->port.func);
+ if (status)
+ kfree(acm);
+ return status;
+}