usb-exchange.c File Reference

#include <assert.h>
#include <dlfcn.h>
#include <pthread.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include "hidapi/hidapi.h"
#include "ca821x-generic-exchange.h"
#include "ca821x-posix-util-internal.h"
#include "ca821x-queue.h"
#include "ca821x_api.h"
#include "usb-exchange.h"

Include dependency graph for usb-exchange.c:

Classes
struct	usb_exchange_priv
	The usb exchange private-data struct representing a single device. More...

Macros
#define	USB_VID   0x0416
#define	USB_PID   0x5020
#define	MAX_FRAG_SIZE   64
	Maximum USB fragment size. More...
#define	POLL_DELAY   2
	Max time to wait on rx data in milliseconds. More...
#define	FRAG_LEN_MASK   0x3F
#define	FRAG_LAST_MASK   (1 << 7)
#define	FRAG_FIRST_MASK   (1 << 6)
#define	ARRAY_LENGTH(array)   (sizeof((array)) / sizeof((array)[0]))
#define	NO_CONST_CHAR(x)   (((char *)(x)))

Functions
void	test_frag_loopback ()
	Run to test fragmentation. More...
void	usb_apply_raspi_workaround (struct ca821x_dev *pDeviceRef)
	This function applies a workaround that is necessary on the Raspberry pi for reliable USB communications. More...
ssize_t	usb_try_read (struct ca821x_dev *pDeviceRef, uint8_t *buf)
ca_error	usb_try_write (const uint8_t *buffer, size_t len, struct ca821x_dev *pDeviceRef)
void	flush_unread_usb (struct ca821x_dev *pDeviceRef)
ca_error	usb_exchange_init (ca821x_errorhandler callback, const char *path, struct ca821x_dev *pDeviceRef, char *serial_num)
	Initialise the usb exchange. More...
void	usb_exchange_deinit (struct ca821x_dev *pDeviceRef)
	Deinitialise the usb exchange, so that it can be reinitialised by another process, or reopened later. More...
ca_error	usb_exchange_enumerate (util_device_found aCallback, void *aContext)
	Function to enumerate all of the USB connected devices, calling aCallback with a struct describing each one. More...
int	usb_exchange_reset (unsigned long resettime, struct ca821x_dev *pDeviceRef)
	Send a hard reset to the ca821x. More...

Macro Definition Documentation

ARRAY_LENGTH

#define ARRAY_LENGTH

(

array

)

(sizeof((array)) / sizeof((array)[0]))

FRAG_FIRST_MASK

#define FRAG_FIRST_MASK   (1 << 6)

FRAG_LAST_MASK

#define FRAG_LAST_MASK   (1 << 7)

FRAG_LEN_MASK

#define FRAG_LEN_MASK   0x3F

MAX_FRAG_SIZE

#define MAX_FRAG_SIZE   64

Maximum USB fragment size.

NO_CONST_CHAR

#define NO_CONST_CHAR

(

x

)

(((char *)(x)))

POLL_DELAY

#define POLL_DELAY   2

Max time to wait on rx data in milliseconds.

USB_PID

#define USB_PID   0x5020

USB_VID

#define USB_VID   0x0416

Function Documentation

flush_unread_usb()

void flush_unread_usb

(

struct ca821x_dev *

pDeviceRef

)

test_frag_loopback()

void test_frag_loopback

(

)

Run to test fragmentation.

Crashes upon fail.

usb_apply_raspi_workaround()

void usb_apply_raspi_workaround

(

struct ca821x_dev *

pDeviceRef

)

This function applies a workaround that is necessary on the Raspberry pi for reliable USB communications.

Essentially, on the raspberry pi, if there is not regular USB transmission to the OUT endpoint, the next OUT transmission will take up to 1000ms to complete. This behaviour has only been observed on the Raspberry pi. The hotfix for this is to send a USB transmission every 1 second on the raspi platform.

usb_exchange_deinit()

void usb_exchange_deinit

(

struct ca821x_dev *

pDeviceRef

)

Deinitialise the usb exchange, so that it can be reinitialised by another process, or reopened later.

Parameters

pDeviceRef

Pointer to initialised ca821x_device_ref struct

usb_exchange_enumerate()

ca_error usb_exchange_enumerate	(	util_device_found	aCallback,
		void *	aContext
	)

Function to enumerate all of the USB connected devices, calling aCallback with a struct describing each one.

The struct passed to aCallback will only be valid for the duration that the function is called. This function will not return until every callback has been called.

Parameters

aCallback	The callback to call with each result
aContext	The generic void pointer to provide to the callback when it is called

Return values

CA_ERROR_SUCCESS	Enumeration successful
CA_ERROR_NOT_FOUND	No devices found

usb_exchange_init()

ca_error usb_exchange_init	(	ca821x_errorhandler	callback,
		const char *	path,
		struct ca821x_dev *	pDeviceRef,
		char *	serial_num
	)

Initialise the usb exchange.

If callback is specified, then it will be used to report any fatal errors back to the application, which can react as required (i.e. crash gracefully or attempt to reset the ca821x)

If path is specified, then the exchange will attempt to open that device, and fail if it cannot. The path of a device can be obtained with usb_exchange_enumerate.

If serial_num is specified, then the exchange will run an additional check when iterating through all devices, looking for one with matching serial number; Otherwise it will carry out the normal iteration and try to open the first available device.

Parameters

[in]	callback	Function pointer to an error-handling callback (can be NULL)
[in]	path	String representing an exchange & system specific path to a device (can be NULL)
[in]	pDeviceRef	Pointer to initialised ca821x_device_ref struct
[in]	serial_num	Serial number of the target device (can be NULL)

Return values

CA_ERROR_SUCCESS	success
CA_ERROR_NOT_FOUND	No available devices found (or device at path not found)
CA_ERROR_NO_ACCESS	The specified path cannot be opened (e.g. no permissions, already in use)
CA_ERROR_ALREADY	The pDeviceRef is already initialised

usb_exchange_reset()

int usb_exchange_reset	(	unsigned long	resettime,
		struct ca821x_dev *	pDeviceRef
	)

Send a hard reset to the ca821x.

This should not be necessary, but is provided in case the ca821x becomes unresponsive to spi.

Parameters

[in]	resettime	The length of time (in ms) to hold the reset pin active for. 1ms is usually a suitable value for this.
[in]	pDeviceRef	Pointer to initialised ca821x_device_ref struct

usb_try_read()

ssize_t usb_try_read	(	struct ca821x_dev *	pDeviceRef,
		uint8_t *	buf
	)

usb_try_write()

ca_error usb_try_write	(	const uint8_t *	buffer,
		size_t	len,
		struct ca821x_dev *	pDeviceRef
	)