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/*
* Copyright (c) 2016-2017 Chris Johns <chrisj@rtems.org>
* All rights reserved.
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
/*
* I2C slave for testing:
* https://github.com/oetr/FPGA-I2C-Slave
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <dev/i2c/i2c.h>
#include <dev/i2c/fpga-i2c-slave.h>
typedef struct {
i2c_dev base;
uint16_t address;
size_t size;
} fpga_i2c_slave;
static ssize_t
fpga_i2c_slave_read(i2c_dev* base, void* buf, size_t n, off_t offset)
{
fpga_i2c_slave* dev = (fpga_i2c_slave*) base;
off_t avail = dev->size - offset;
uint8_t* in = buf;
size_t todo;
if (avail <= 0) {
return 0;
}
if (n > avail) {
n = (size_t) avail;
}
todo = n;
while (todo > 0) {
/*
* Limit the transfer size so that it can be stored in 8-bits. This may
* help some bus controllers.
*/
uint16_t cur = (uint16_t) (todo < 255 ? todo : 255);
i2c_msg msgs = {
.addr = dev->base.address,
.flags = I2C_M_RD,
.buf = in,
.len = cur
};
int err;
err = i2c_bus_transfer(dev->base.bus, &msgs, 1);
if (err != 0) {
return err;
}
todo -= cur;
in += cur;
}
return (ssize_t) n;
}
static ssize_t
fpga_i2c_slave_write(i2c_dev* base, const void* buf, size_t n, off_t offset)
{
fpga_i2c_slave* dev = (fpga_i2c_slave*) base;
off_t avail = dev->size - offset;
const uint8_t* out = buf;
size_t todo;
if (avail <= 0) {
return 0;
}
if (n > avail) {
n = (size_t) avail;
}
todo = n;
while (todo > 0) {
/*
* Limit the transfer size so that it can be stored in 8-bits. This may
* help some bus controllers.
*/
uint16_t cur = (uint16_t) (todo < 255 ? todo : 255);
i2c_msg msgs = {
.addr = dev->base.address,
.flags = 0,
.buf = RTEMS_DECONST(uint8_t*, out),
.len = cur
};
int err;
err = i2c_bus_transfer(dev->base.bus, &msgs, 1);
if (err != 0) {
return err;
}
todo -= cur;
out += cur;
}
return (ssize_t) n;
}
int
i2c_dev_register_fpga_i2c_slave(const char* bus_path,
const char* dev_path,
uint16_t address,
size_t size)
{
fpga_i2c_slave* dev;
dev = (fpga_i2c_slave*)
i2c_dev_alloc_and_init(sizeof(*dev), bus_path, address);
if (dev == NULL) {
return -1;
}
dev->base.read = fpga_i2c_slave_read;
dev->base.write = fpga_i2c_slave_write;
dev->size = size;
return i2c_dev_register(&dev->base, dev_path);
}
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