drivers/usb/gadget/function/f_serial.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * f_serial.c - generic USB serial function driver
   4  *
   5  * Copyright (C) 2003 Al Borchers (alborchers@steinerpoint.com)
   6  * Copyright (C) 2008 by David Brownell
   7  * Copyright (C) 2008 by Nokia Corporation
   8  */
   9
  10 #include <linux/slab.h>
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/device.h>
  14
  15 #include "u_serial.h"
  16
  17
  18 /*
  19  * This function packages a simple "generic serial" port with no real
  20  * control mechanisms, just raw data transfer over two bulk endpoints.
  21  *
  22  * Because it's not standardized, this isn't as interoperable as the
  23  * CDC ACM driver.  However, for many purposes it's just as functional
  24  * if you can arrange appropriate host side drivers.
  25  */
  26
  27 struct f_gser {
  28         struct gserial                  port;
  29         u8                              data_id;
  30         u8                              port_num;
  31 };
  32
  33 static inline struct f_gser *func_to_gser(struct usb_function *f)
  34 {
  35         return container_of(f, struct f_gser, port.func);
  36 }
  37
  38 /*-------------------------------------------------------------------------*/
  39
  40 /* interface descriptor: */
  41
  42 static struct usb_interface_descriptor gser_interface_desc = {
  43         .bLength =              USB_DT_INTERFACE_SIZE,
  44         .bDescriptorType =      USB_DT_INTERFACE,
  45         /* .bInterfaceNumber = DYNAMIC */
  46         .bNumEndpoints =        2,
  47         .bInterfaceClass =      USB_CLASS_VENDOR_SPEC,
  48         .bInterfaceSubClass =   0,
  49         .bInterfaceProtocol =   0,
  50         /* .iInterface = DYNAMIC */
  51 };
  52
  53 /* full speed support: */
  54
  55 static struct usb_endpoint_descriptor gser_fs_in_desc = {
  56         .bLength =              USB_DT_ENDPOINT_SIZE,
  57         .bDescriptorType =      USB_DT_ENDPOINT,
  58         .bEndpointAddress =     USB_DIR_IN,
  59         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
  60 };
  61
  62 static struct usb_endpoint_descriptor gser_fs_out_desc = {
  63         .bLength =              USB_DT_ENDPOINT_SIZE,
  64         .bDescriptorType =      USB_DT_ENDPOINT,
  65         .bEndpointAddress =     USB_DIR_OUT,
  66         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
  67 };
  68
  69 static struct usb_descriptor_header *gser_fs_function[] = {
  70         (struct usb_descriptor_header *) &gser_interface_desc,
  71         (struct usb_descriptor_header *) &gser_fs_in_desc,
  72         (struct usb_descriptor_header *) &gser_fs_out_desc,
  73         NULL,
  74 };
  75
  76 /* high speed support: */
  77
  78 static struct usb_endpoint_descriptor gser_hs_in_desc = {
  79         .bLength =              USB_DT_ENDPOINT_SIZE,
  80         .bDescriptorType =      USB_DT_ENDPOINT,
  81         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
  82         .wMaxPacketSize =       cpu_to_le16(512),
  83 };
  84
  85 static struct usb_endpoint_descriptor gser_hs_out_desc = {
  86         .bLength =              USB_DT_ENDPOINT_SIZE,
  87         .bDescriptorType =      USB_DT_ENDPOINT,
  88         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
  89         .wMaxPacketSize =       cpu_to_le16(512),
  90 };
  91
  92 static struct usb_descriptor_header *gser_hs_function[] = {
  93         (struct usb_descriptor_header *) &gser_interface_desc,
  94         (struct usb_descriptor_header *) &gser_hs_in_desc,
  95         (struct usb_descriptor_header *) &gser_hs_out_desc,
  96         NULL,
  97 };
  98
  99 static struct usb_endpoint_descriptor gser_ss_in_desc = {
 100         .bLength =              USB_DT_ENDPOINT_SIZE,
 101         .bDescriptorType =      USB_DT_ENDPOINT,
 102         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 103         .wMaxPacketSize =       cpu_to_le16(1024),
 104 };
 105
 106 static struct usb_endpoint_descriptor gser_ss_out_desc = {
 107         .bLength =              USB_DT_ENDPOINT_SIZE,
 108         .bDescriptorType =      USB_DT_ENDPOINT,
 109         .bmAttributes =         USB_ENDPOINT_XFER_BULK,
 110         .wMaxPacketSize =       cpu_to_le16(1024),
 111 };
 112
 113 static struct usb_ss_ep_comp_descriptor gser_ss_bulk_comp_desc = {
 114         .bLength =              sizeof gser_ss_bulk_comp_desc,
 115         .bDescriptorType =      USB_DT_SS_ENDPOINT_COMP,
 116 };
 117
 118 static struct usb_descriptor_header *gser_ss_function[] = {
 119         (struct usb_descriptor_header *) &gser_interface_desc,
 120         (struct usb_descriptor_header *) &gser_ss_in_desc,
 121         (struct usb_descriptor_header *) &gser_ss_bulk_comp_desc,
 122         (struct usb_descriptor_header *) &gser_ss_out_desc,
 123         (struct usb_descriptor_header *) &gser_ss_bulk_comp_desc,
 124         NULL,
 125 };
 126
 127 /* string descriptors: */
 128
 129 static struct usb_string gser_string_defs[] = {
 130         [0].s = "Generic Serial",
 131         {  } /* end of list */
 132 };
 133
 134 static struct usb_gadget_strings gser_string_table = {
 135         .language =             0x0409, /* en-us */
 136         .strings =              gser_string_defs,
 137 };
 138
 139 static struct usb_gadget_strings *gser_strings[] = {
 140         &gser_string_table,
 141         NULL,
 142 };
 143
 144 /*-------------------------------------------------------------------------*/
 145
 146 static int gser_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 147 {
 148         struct f_gser           *gser = func_to_gser(f);
 149         struct usb_composite_dev *cdev = f->config->cdev;
 150
 151         /* we know alt == 0, so this is an activation or a reset */
 152
 153         if (gser->port.in->enabled) {
 154                 dev_dbg(&cdev->gadget->dev,
 155                         "reset generic ttyGS%d\n", gser->port_num);
 156                 gserial_disconnect(&gser->port);
 157         }
 158         if (!gser->port.in->desc || !gser->port.out->desc) {
 159                 dev_dbg(&cdev->gadget->dev,
 160                         "activate generic ttyGS%d\n", gser->port_num);
 161                 if (config_ep_by_speed(cdev->gadget, f, gser->port.in) ||
 162                     config_ep_by_speed(cdev->gadget, f, gser->port.out)) {
 163                         gser->port.in->desc = NULL;
 164                         gser->port.out->desc = NULL;
 165                         return -EINVAL;
 166                 }
 167         }
 168         gserial_connect(&gser->port, gser->port_num);
 169         return 0;
 170 }
 171
 172 static void gser_disable(struct usb_function *f)
 173 {
 174         struct f_gser   *gser = func_to_gser(f);
 175         struct usb_composite_dev *cdev = f->config->cdev;
 176
 177         dev_dbg(&cdev->gadget->dev,
 178                 "generic ttyGS%d deactivated\n", gser->port_num);
 179         gserial_disconnect(&gser->port);
 180 }
 181
 182 /*-------------------------------------------------------------------------*/
 183
 184 /* serial function driver setup/binding */
 185
 186 static int gser_bind(struct usb_configuration *c, struct usb_function *f)
 187 {
 188         struct usb_composite_dev *cdev = c->cdev;
 189         struct f_gser           *gser = func_to_gser(f);
 190         int                     status;
 191         struct usb_ep           *ep;
 192
 193         /* REVISIT might want instance-specific strings to help
 194          * distinguish instances ...
 195          */
 196
 197         /* maybe allocate device-global string ID */
 198         if (gser_string_defs[0].id == 0) {
 199                 status = usb_string_id(c->cdev);
 200                 if (status < 0)
 201                         return status;
 202                 gser_string_defs[0].id = status;
 203         }
 204
 205         /* allocate instance-specific interface IDs */
 206         status = usb_interface_id(c, f);
 207         if (status < 0)
 208                 goto fail;
 209         gser->data_id = status;
 210         gser_interface_desc.bInterfaceNumber = status;
 211
 212         status = -ENODEV;
 213
 214         /* allocate instance-specific endpoints */
 215         ep = usb_ep_autoconfig(cdev->gadget, &gser_fs_in_desc);
 216         if (!ep)
 217                 goto fail;
 218         gser->port.in = ep;
 219
 220         ep = usb_ep_autoconfig(cdev->gadget, &gser_fs_out_desc);
 221         if (!ep)
 222                 goto fail;
 223         gser->port.out = ep;
 224
 225         /* support all relevant hardware speeds... we expect that when
 226          * hardware is dual speed, all bulk-capable endpoints work at
 227          * both speeds
 228          */
 229         gser_hs_in_desc.bEndpointAddress = gser_fs_in_desc.bEndpointAddress;
 230         gser_hs_out_desc.bEndpointAddress = gser_fs_out_desc.bEndpointAddress;
 231
 232         gser_ss_in_desc.bEndpointAddress = gser_fs_in_desc.bEndpointAddress;
 233         gser_ss_out_desc.bEndpointAddress = gser_fs_out_desc.bEndpointAddress;
 234
 235         status = usb_assign_descriptors(f, gser_fs_function, gser_hs_function,
 236                         gser_ss_function, gser_ss_function);
 237         if (status)
 238                 goto fail;
 239         dev_dbg(&cdev->gadget->dev, "generic ttyGS%d: %s speed IN/%s OUT/%s\n",
 240                 gser->port_num,
 241                 gadget_is_superspeed(c->cdev->gadget) ? "super" :
 242                 gadget_is_dualspeed(c->cdev->gadget) ? "dual" : "full",
 243                 gser->port.in->name, gser->port.out->name);
 244         return 0;
 245
 246 fail:
 247         ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
 248
 249         return status;
 250 }
 251
 252 static inline struct f_serial_opts *to_f_serial_opts(struct config_item *item)
 253 {
 254         return container_of(to_config_group(item), struct f_serial_opts,
 255                             func_inst.group);
 256 }
 257
 258 static void serial_attr_release(struct config_item *item)
 259 {
 260         struct f_serial_opts *opts = to_f_serial_opts(item);
 261
 262         usb_put_function_instance(&opts->func_inst);
 263 }
 264
 265 static struct configfs_item_operations serial_item_ops = {
 266         .release        = serial_attr_release,
 267 };
 268
 269 static ssize_t f_serial_port_num_show(struct config_item *item, char *page)
 270 {
 271         return sprintf(page, "%u\n", to_f_serial_opts(item)->port_num);
 272 }
 273
 274 CONFIGFS_ATTR_RO(f_serial_, port_num);
 275
 276 static struct configfs_attribute *acm_attrs[] = {
 277         &f_serial_attr_port_num,
 278         NULL,
 279 };
 280
 281 static const struct config_item_type serial_func_type = {
 282         .ct_item_ops    = &serial_item_ops,
 283         .ct_attrs       = acm_attrs,
 284         .ct_owner       = THIS_MODULE,
 285 };
 286
 287 static void gser_free_inst(struct usb_function_instance *f)
 288 {
 289         struct f_serial_opts *opts;
 290
 291         opts = container_of(f, struct f_serial_opts, func_inst);
 292         gserial_free_line(opts->port_num);
 293         kfree(opts);
 294 }
 295
 296 static struct usb_function_instance *gser_alloc_inst(void)
 297 {
 298         struct f_serial_opts *opts;
 299         int ret;
 300
 301         opts = kzalloc(sizeof(*opts), GFP_KERNEL);
 302         if (!opts)
 303                 return ERR_PTR(-ENOMEM);
 304
 305         opts->func_inst.free_func_inst = gser_free_inst;
 306         ret = gserial_alloc_line(&opts->port_num);
 307         if (ret) {
 308                 kfree(opts);
 309                 return ERR_PTR(ret);
 310         }
 311         config_group_init_type_name(&opts->func_inst.group, "",
 312                                     &serial_func_type);
 313
 314         return &opts->func_inst;
 315 }
 316
 317 static void gser_free(struct usb_function *f)
 318 {
 319         struct f_gser *serial;
 320
 321         serial = func_to_gser(f);
 322         kfree(serial);
 323 }
 324
 325 static void gser_unbind(struct usb_configuration *c, struct usb_function *f)
 326 {
 327         usb_free_all_descriptors(f);
 328 }
 329
 330 static struct usb_function *gser_alloc(struct usb_function_instance *fi)
 331 {
 332         struct f_gser   *gser;
 333         struct f_serial_opts *opts;
 334
 335         /* allocate and initialize one new instance */
 336         gser = kzalloc(sizeof(*gser), GFP_KERNEL);
 337         if (!gser)
 338                 return ERR_PTR(-ENOMEM);
 339
 340         opts = container_of(fi, struct f_serial_opts, func_inst);
 341
 342         gser->port_num = opts->port_num;
 343
 344         gser->port.func.name = "gser";
 345         gser->port.func.strings = gser_strings;
 346         gser->port.func.bind = gser_bind;
 347         gser->port.func.unbind = gser_unbind;
 348         gser->port.func.set_alt = gser_set_alt;
 349         gser->port.func.disable = gser_disable;
 350         gser->port.func.free_func = gser_free;
 351
 352         return &gser->port.func;
 353 }
 354
 355 DECLARE_USB_FUNCTION_INIT(gser, gser_alloc_inst, gser_alloc);
 356 MODULE_LICENSE("GPL");
 357 MODULE_AUTHOR("Al Borchers");
 358 MODULE_AUTHOR("David Brownell");