text: /* Simple Raw HID functions for Linux - for use with Teensy RawHID example
   * http://www.pjrc.com/teensy/rawhid.html
   * Copyright (c) 2009 PJRC.COM, LLC
   *
   *  rawhid_open - open 1 or more devices
   *  rawhid_recv - receive a packet
   *  rawhid_send - send a packet
   *  rawhid_close - close a device
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   * 
   * The above description, website URL and copyright notice and this permission
   * notice shall be included in all copies or substantial portions of the Software.
   * 
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   *
   * Version 1.0: Initial Release
   */
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <stdint.h>
  #include <usb.h>
  
  #include "hid.h"
  
  
  // On Linux there are several options to access HID devices.
  //
  // libusb 0.1 - the only way that works well on all distributions
  // libusb 1.0 - someday will become standard on most distributions
  // hidraw driver - relatively new, not supported on many distributions (yet)
  // hiddev driver - old, ubuntu, fedora, others dropping support
  // usbfs - low level usb API: http://www.kernel.org/doc/htmldocs/usb.html#usbfs
  //
  // This code uses libusb 0.1, which is well supported on all linux distributions
  // and very stable and widely used by many programs.  libusb 0.1 only provides a
  // simple synchronous interface, basically the same as this code needs.  However,
  // if you want non-blocking I/O, libusb 0.1 simply does not provide that.  There
  // is also no kernel-level buffering, so performance is poor.
  //
  // UPDATE: As of November 2011, hidraw support seems to be working well in all
  // major linux distributions.  Embedded and "small" distros, used on ARM boards,
  // routers and embedded hardware stil seem to omit the hidraw driver.
  //
  // The hidraw driver is a great solution.  However, it has only been supported
  // by relatively recent (in 2009) kernels.  Here is a quick survey of the status
  // of hidraw support in various distributions as of Sept 2009:
  //
  // Fedora 11: works, kernel 2.6.29.4
  // Mandiva 2009.1: works, kernel 2.6.29.1
  // Ubuntu 9.10-alpha6: works, kernel 2.6.31
  // Ubuntu 9.04: sysfs attrs chain broken (hidraw root only), 2.6.28 kernel
  // openSUSE 11.1: sysfs attrs chain broken (hidraw root only), 2.6.27.7 kernel
  // Debian Live, Lenny 5.0.2: sysfs attrs chain broken (hidraw root only), 2.6.26
  // SimplyMEPIS 8.0.10: sysfs attrs chain broken (hidraw root only), 2.6.27
  // Mint 7: sysfs attrs chain broken (hidraw root only), 2.6.28 kernel
  // Gentoo 2008.0-r1: sysfs attrs chain broken (hidraw root only), 2.6.24 kernel
  // Centos 5: no hidraw or hiddev devices, 2.6.18 kernel
  // Slitaz 2.0: no hidraw devices (has hiddev), 2.6.25.5 kernel
  // Puppy 4.3: no hidraw devices (has hiddev), 2.6.30.5 kernel
  // Damn Small 4.4.10: (would not boot)
  // Gentoo 10.0-test20090926: (would not boot)
  // PCLinuxOS 2009.2: (would not boot) 
  // Slackware: (no live cd available?  www.slackware-live.org dead)
  
  
  
  #define printf(...)  // comment this out for lots of info
  
  
  // a list of all opened HID devices, so the caller can
  // simply refer to them by number
  typedef struct hid_struct hid_t;
  static hid_t *first_hid = NULL;
  static hid_t *last_hid = NULL;
  struct hid_struct {
  	usb_dev_handle *usb;
  	int open;
  	int iface;
  	int ep_in;
  	int ep_out;
  	struct hid_struct *prev;
  	struct hid_struct *next;
  };
  
  
  // private functions, not intended to be used from outside this file
  static void add_hid(hid_t *h);
  static hid_t * get_hid(int num);
  static void free_all_hid(void);
  static void hid_close(hid_t *hid);
  static int hid_parse_item(uint32_t *val, uint8_t **data, const uint8_t *end);
  
  
  //  rawhid_recv - receive a packet
  //    Inputs:
  //	num = device to receive from (zero based)
  //	buf = buffer to receive packet
  //	len = buffer's size
  //	timeout = time to wait, in milliseconds
  //    Output:
  //	number of bytes received, or -1 on error
  //
  int rawhid_recv(int num, void *buf, int len, int timeout)
  {
  	hid_t *hid;
  	int r;
  
  	hid = get_hid(num);
  	if (!hid || !hid->open) return -1;
  	r = usb_interrupt_read(hid->usb, hid->ep_in, (char*)buf, len, timeout);
  	if (r >= 0) return r;
  	if (r == -110) return 0;  // timeout
  	return -1;
  }
  
  //  rawhid_send - send a packet
  //    Inputs:
  //	num = device to transmit to (zero based)
  //	buf = buffer containing packet to send
  //	len = number of bytes to transmit
  //	timeout = time to wait, in milliseconds
  //    Output:
  //	number of bytes sent, or -1 on error
  //
  int rawhid_send(int num, void *buf, int len, int timeout)
  {
  	hid_t *hid;
  
  	hid = get_hid(num);
  	if (!hid || !hid->open) return -1;
  	if (hid->ep_out) {
  		return usb_interrupt_write(hid->usb, hid->ep_out, (char*)buf, len, timeout);
  	} else {
  		return usb_control_msg(hid->usb, 0x21, 9, 0, hid->iface, (char*)buf, len, timeout);
  	}
  }
  
  //  rawhid_open - open 1 or more devices
  //
  //    Inputs:
  //	max = maximum number of devices to open
  //	vid = Vendor ID, or -1 if any
  //	pid = Product ID, or -1 if any
  //	usage_page = top level usage page, or -1 if any
  //	usage = top level usage number, or -1 if any
  //    Output:
  //	actual number of devices opened
  //
  int rawhid_open(int max, int vid, int pid, int usage_page, int usage)
  {
  	struct usb_bus *bus;
  	struct usb_device *dev;
  	struct usb_interface *iface;
  	struct usb_interface_descriptor *desc;
  	struct usb_endpoint_descriptor *ep;
  	usb_dev_handle *u;
  	uint8_t buf[1024], *p;
  	int i, n, len, tag, ep_in, ep_out, count=0, claimed;
  	uint32_t val=0, parsed_usage, parsed_usage_page;
  	hid_t *hid;
  
  	if (first_hid) free_all_hid();
  	printf("rawhid_open, max=%d\n", max);
  	if (max < 1) return 0;
  	usb_init();
  	usb_find_busses();
  	usb_find_devices();
  	for (bus = usb_get_busses(); bus; bus = bus->next) {
  		for (dev = bus->devices; dev; dev = dev->next) {
  			if (vid > 0 && dev->descriptor.idVendor != vid) continue;
  			if (pid > 0 && dev->descriptor.idProduct != pid) continue;
  			if (!dev->config) continue;
  			if (dev->config->bNumInterfaces < 1) continue;
  			printf("device: vid=%04X, pic=%04X, with %d iface\n",
  				dev->descriptor.idVendor,
  				dev->descriptor.idProduct,
  				dev->config->bNumInterfaces);
  			iface = dev->config->interface;
  			u = NULL;
  			claimed = 0;
  			for (i=0; i<dev->config->bNumInterfaces && iface; i++, iface++) {
  				desc = iface->altsetting;
  				if (!desc) continue;
  				printf("  type %d, %d, %d\n", desc->bInterfaceClass,
  					desc->bInterfaceSubClass, desc->bInterfaceProtocol);
  				if (desc->bInterfaceClass != 3) continue;
  				if (desc->bInterfaceSubClass != 0) continue;
  				if (desc->bInterfaceProtocol != 0) continue;
  				ep = desc->endpoint;
  				ep_in = ep_out = 0;
  				for (n = 0; n < desc->bNumEndpoints; n++, ep++) {
  					if (ep->bEndpointAddress & 0x80) {
  						if (!ep_in) ep_in = ep->bEndpointAddress & 0x7F;
  						printf("    IN endpoint %d\n", ep_in);
  					} else {
  						if (!ep_out) ep_out = ep->bEndpointAddress;
  						printf("    OUT endpoint %d\n", ep_out);
  					}
  				}
  				if (!ep_in) continue;
  				if (!u) {
  					u = usb_open(dev);
  					if (!u) {
  						printf("  unable to open device\n");
  						break;
  					}
  				}
  				printf("  hid interface (generic)\n");
  				if (usb_get_driver_np(u, i, (char *)buf, sizeof(buf)) >= 0) {
  					printf("  in use by driver \"%s\"\n", buf);
  					if (usb_detach_kernel_driver_np(u, i) < 0) {
  						printf("  unable to detach from kernel\n");
  						continue;
  					}
  				}
  				if (usb_claim_interface(u, i) < 0) {
  					printf("  unable claim interface %d\n", i);
  					continue;
  				}
  				len = usb_control_msg(u, 0x81, 6, 0x2200, i, (char *)buf, sizeof(buf), 250);
  					printf("  descriptor, len=%d\n", len);
  				if (len < 2) {
  					usb_release_interface(u, i);
  					continue;
  				}
  				p = buf;
  				parsed_usage_page = parsed_usage = 0;
  				while ((tag = hid_parse_item(&val, &p, buf + len)) >= 0) {
  					printf("  tag: %X, val %X\n", tag, val);
  					if (tag == 4) parsed_usage_page = val;
  					if (tag == 8) parsed_usage = val;
  					if (parsed_usage_page && parsed_usage) break;
  				}
  				if ((!parsed_usage_page) || (!parsed_usage) ||
  				  (usage_page > 0 && parsed_usage_page != usage_page) || 
  				  (usage > 0 && parsed_usage != usage)) {
  					usb_release_interface(u, i);
  					continue;
  				}
  				hid = (struct hid_struct *)malloc(sizeof(struct hid_struct));
  				if (!hid) {
  					usb_release_interface(u, i);
  					continue;
  				}
  				hid->usb = u;
  				hid->iface = i;
  				hid->ep_in = ep_in;
  				hid->ep_out = ep_out;
  				hid->open = 1;
  				add_hid(hid);
  				claimed++;
  				count++;
  				if (count >= max) return count;
  			}
  			if (u && !claimed) usb_close(u);
  		}
  	}
  	return count;
  }
  
  
  //  rawhid_close - close a device
  //
  //    Inputs:
  //	num = device to close (zero based)
  //    Output
  //	(nothing)
  //
  void rawhid_close(int num)
  {
  	hid_t *hid;
  
  	hid = get_hid(num);
  	if (!hid || !hid->open) return;
  	hid_close(hid);
  }
  
  // Chuck Robey wrote a real HID report parser
  // (chuckr@telenix.org) chuckr@chuckr.org
  // http://people.freebsd.org/~chuckr/code/python/uhidParser-0.2.tbz
  // this tiny thing only needs to extract the top-level usage page
  // and usage, and even then is may not be truly correct, but it does
  // work with the Teensy Raw HID example.
  static int hid_parse_item(uint32_t *val, uint8_t **data, const uint8_t *end)
  {
  	const uint8_t *p = *data;
  	uint8_t tag;
  	int table[4] = {0, 1, 2, 4};
  	int len;
  
  	if (p >= end) return -1;
  	if (p[0] == 0xFE) {
  		// long item, HID 1.11, 6.2.2.3, page 27
  		if (p + 5 >= end || p + p[1] >= end) return -1;
  		tag = p[2];
  		*val = 0;
  		len = p[1] + 5;
  	} else {
  		// short item, HID 1.11, 6.2.2.2, page 26
  		tag = p[0] & 0xFC;
  		len = table[p[0] & 0x03];
  		if (p + len + 1 >= end) return -1;
  		switch (p[0] & 0x03) {
  		  case 3: *val = p[1] | (p[2] << 8) | (p[3] << 16) | (p[4] << 24); break;
  		  case 2: *val = p[1] | (p[2] << 8); break;
  		  case 1: *val = p[1]; break;
  		  case 0: *val = 0; break;
  		}
  	}
  	*data += len + 1;
  	return tag;
  }
  
  
  static void add_hid(hid_t *h)
  {
  	if (!first_hid || !last_hid) {
  		first_hid = last_hid = h;
  		h->next = h->prev = NULL;
  		return;
  	}
  	last_hid->next = h;
  	h->prev = last_hid;
  	h->next = NULL;
  	last_hid = h;
  }
  
  
  static hid_t * get_hid(int num)
  {
  	hid_t *p;
  	for (p = first_hid; p && num > 0; p = p->next, num--) ;
  	return p;
  }
  
  
  static void free_all_hid(void)
  {
  	hid_t *p, *q;
  
  	for (p = first_hid; p; p = p->next) {
  		hid_close(p);
  	}
  	p = first_hid;
  	while (p) {
  		q = p;
  		p = p->next;
  		free(q);
  	}
  	first_hid = last_hid = NULL;
  }
  
  
  static void hid_close(hid_t *hid)
  {
  	hid_t *p;
  	int others=0;
  
  	usb_release_interface(hid->usb, hid->iface);
  	for (p = first_hid; p; p = p->next) {
  		if (p->open && p->usb == hid->usb) others++;
  	}
  	if (!others) usb_close(hid->usb);
  	hid->usb = NULL;
  }
  
  
  
  