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// Very basic shift-register support via a Linux SPI device
//
// Copyright (C) 2017-2018 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include <fcntl.h> // open
#include <stdio.h> // snprintf
#include <unistd.h> // write
#include "command.h" // DECL_COMMAND
#include "gpio.h" // spi_setup
#include "internal.h" // report_errno
#include "sched.h" // shutdown
struct spi_s {
uint32_t bus, dev;
int fd;
};
static struct spi_s devices[16];
static int devices_count;
static int
spi_open(uint32_t bus, uint32_t dev)
{
// Find existing device (if already opened)
int i;
for (i=0; i<devices_count; i++)
if (devices[i].bus == bus && devices[i].dev == dev)
return devices[i].fd;
// Setup new SPI device
if (devices_count >= ARRAY_SIZE(devices))
shutdown("Too many spi devices");
char fname[256];
snprintf(fname, sizeof(fname), "/dev/spidev%d.%d", bus, dev);
int fd = open(fname, O_RDWR|O_CLOEXEC);
if (fd < 0) {
report_errno("open spi", fd);
shutdown("Unable to open spi device");
}
int ret = set_non_blocking(fd);
if (ret < 0)
shutdown("Unable to set non-blocking on spi device");
devices[devices_count].bus = bus;
devices[devices_count].dev = dev;
devices[devices_count].fd = fd;
return fd;
}
struct spi_config
spi_setup(uint32_t bus, uint8_t mode, uint32_t rate)
{
int bus_id = (bus >> 8) & 0xff, dev_id = bus & 0xff;
int fd = spi_open(bus_id, dev_id);
return (struct spi_config) { fd };
}
void
spi_prepare(struct spi_config config)
{
}
void
spi_transfer(struct spi_config config, uint8_t receive_data
, uint8_t len, uint8_t *data)
{
int ret = write(config.fd, data, len);
if (ret < 0) {
report_errno("write spi", ret);
shutdown("Unable to write to spi");
}
}
// Dummy versions of gpio_out functions
struct gpio_out
gpio_out_setup(uint8_t pin, uint8_t val)
{
shutdown("gpio_out_setup not supported");
}
void
gpio_out_write(struct gpio_out g, uint8_t val)
{
}
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