Sample Apps: App to talk to spidev devices

This patch adds a sample application "spi_xfer" to talk to
 spidev devices like FPGA, IMU and CAN in the Aero platform.

This sample app is based off of the similar application "spitr"
which can be found at https://github.com/icpda/sample_apps/tree/master/spi_tools

Signed-off-by: Jayaraman, Venkat <[email protected]>

spidev-app/spi_xfer.c

@@ -0,0 +1,158 @@
+/* SPI Transfer basic application
+ *
+ *  Copyright (c) 2016 Intel Corporation
+ *
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License version 2 as published
+ *  by the Free Software Foundation.
+ *
+ *  Author: Israel Cepeda <[email protected]>
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <sys/ioctl.h>
+#include <linux/spi/spidev.h>
+
+#define SPIDEV "/dev/spidev%d.%d"
+
+struct spidev {
+	char node[20];
+	uint8_t mode;
+	uint8_t bits;
+	uint32_t speed;
+	int fd;
+};
+
+struct transfer {
+	int words;
+	long data;
+	int len;
+};
+
+/*
+ * Transfer function
+ */
+void transfer(struct spidev *dev, struct transfer *tr)
+{
+	struct spi_ioc_transfer iotr;
+	uint8_t *tx, *rx;
+	int ret, len = dev->bits/8 * tr->words;
+	int i;
+
+	if (len < tr->len)
+		len = tr->len;
+
+	tx = malloc(len);
+	rx = malloc(len);
+
+	if (!tx || !rx) {
+		printf("ERROR: No memory\n");
+		return;
+	}
+
+	memcpy(tx, &tr->data, tr->len);
+	memset(&tx[tr->len], 0x00, len - tr->len);
+	memset(rx, 0xff, len);
+
+	printf("TX: ");
+	for (i = 0; i < len; i++)
+		printf("0x%x ", tx[i]);
+	printf("\n");
+
+	/* prepare transfer */
+	iotr.tx_buf = (unsigned long)tx;
+	iotr.rx_buf = (unsigned long)rx;
+	iotr.len = len;
+
+	ret = ioctl(dev->fd, SPI_IOC_MESSAGE(1), &iotr);
+	if (ret < 1)
+		printf("ERROR: failed to transfer %s\n", dev->node);
+	else {
+		printf("RX: ");
+		for (i = 0; i < len; i++)
+			printf("0x%x ", rx[i]);
+		printf("\n");
+	}
+
+	free(tx);
+	free(rx);
+}
+
+/*
+ * Main function
+ */
+int main(int argc, char **argv)
+{
+	struct spidev dev;
+	struct transfer tr;
+	int bus = 0, cs = 0, words = 0, ret = 0;
+	char c, *data = 0;
+
+	while ((c = getopt(argc, argv, "b:c:w:d:")) != -1) {
+		switch (c) {
+		case 'b':
+			bus = atoi(optarg);
+			break;
+		case 'c':
+			cs = atoi(optarg);
+			break;
+		case 'd':
+			data = optarg;
+			break;
+		case 'w':
+			words = atoi(optarg);
+			break;
+		default:
+			return -1;
+		}
+	}
+
+	sprintf(dev.node, SPIDEV, bus, cs);
+
+	/* open spi device */
+	dev.fd = open(dev.node, O_RDWR);
+	if (dev.fd < 0) {
+		printf("ERROR: failed to open %s\n", dev.node);
+		ret = -errno;
+		return ret;
+	}
+
+	/* spi mode */
+	ret = ioctl(dev.fd, SPI_IOC_RD_MODE, &dev.mode);
+	if (ret == -1)
+		printf("ERROR: faild to get mode %s\n", dev.node);
+
+	/* bits per word */
+	ret = ioctl(dev.fd, SPI_IOC_RD_BITS_PER_WORD, &dev.bits);
+	if (ret == -1)
+		printf("ERROR: faild to get bits per word %s\n", dev.node);
+
+	/* max speed hz */
+	ret = ioctl(dev.fd, SPI_IOC_RD_MAX_SPEED_HZ, &dev.speed);
+	if (ret == -1)
+		printf("ERROR: faild to get max speed hz %s\n", dev.node);
+
+	/* spi device info */
+	printf("spi mode: %d\n", dev.mode);
+	printf("bits per word: %d\n", dev.bits);
+	printf("max speed: %d Hz\n", dev.speed);
+
+	if (data) {
+		tr.words = words > 0 ? words : 1;
+		tr.data = strtol(data, NULL, 16);
+		tr.len = strlen(data) / (2 * dev.bits / 8);
+		transfer(&dev, &tr);
+	} else
+		printf("ERROR: No data specified\n");
+
+	/* close spi device */
+	close(dev.fd);
+
+	return ret;
+}