linux_spi.c

/*
 * This file is part of the flashrom project.
 *
 * Copyright (C) 2011 Sven Schnelle <svens@stackframe.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#if CONFIG_LINUX_SPI == 1

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h>
#include <inttypes.h>
#include <fcntl.h>
#include <errno.h>
#include <ctype.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/types.h>
#include "file.h"
#include "flash.h"
#include "chipdrivers.h"
#include "programmer.h"
#include "spi.h"
/*
 * Linux versions prior to v4.14-rc7 may need linux/ioctl.h included here due
 * to missing from linux/spi/spidev.h. This was fixed in the following commit:
 * a2b4a79b88b2 spi: uapi: spidev: add missing ioctl header
 */
#include <linux/ioctl.h>
#include <linux/spi/spidev.h>

/* Devices known to work with this module (FIXME: export as struct dev_entry):
 * Beagle Bone Black
 * Raspberry Pi
 * HummingBoard
 */

static int fd = -1;
#define BUF_SIZE_FROM_SYSFS	"/sys/module/spidev/parameters/bufsiz"
static size_t max_kernel_buf_size;

static int linux_spi_shutdown(void *data);
static int linux_spi_send_command(const struct flashctx *flash, unsigned int writecnt,
				  unsigned int readcnt,
				  const unsigned char *txbuf,
				  unsigned char *rxbuf);
static int linux_spi_read(struct flashctx *flash, uint8_t *buf,
			  unsigned int start, unsigned int len);
static int linux_spi_write_256(struct flashctx *flash, const uint8_t *buf,
			       unsigned int start, unsigned int len);

static const struct spi_master spi_master_linux = {
	.features	= SPI_MASTER_4BA,
	.max_data_read	= MAX_DATA_UNSPECIFIED, /* TODO? */
	.max_data_write	= MAX_DATA_UNSPECIFIED, /* TODO? */
	.command	= linux_spi_send_command,
	.multicommand	= default_spi_send_multicommand,
	.read		= linux_spi_read,
	.write_256	= linux_spi_write_256,
};

static char devfs_path[32]; 	/* at least big enough to fit /dev/spidevX.Y */
static char *check_fdt(void)
{
	unsigned int bus, cs;

	if (fdt_find_spi_nor_flash(&bus, &cs) < 0)
		return NULL;

	sprintf(devfs_path, "/dev/spidev%u.%u", bus, cs);
	return devfs_path;
}

int linux_spi_init(void)
{
	char *p, *endp, *dev;
	uint32_t speed_hz = 2 * 1000 * 1000;
	/* FIXME: make the following configurable by CLI options. */
	/* SPI mode 0 (beware this also includes: MSB first, CS active low and others */
	const uint8_t mode = SPI_MODE_0;
	const uint8_t bits = 8;

	/*
	 * FIXME: There might be other programmers with flash memory (such as
	 * an EC) connected via SPI. For now we rely on the device's driver to
	 * distinguish it and assume generic SPI implies host.
	 */
	if (alias && alias->type != ALIAS_HOST)
		return 1;

	dev = extract_programmer_param("dev");
	if (!dev)
		dev = check_fdt();
	if (!dev || !strlen(dev)) {
		msg_perr("No SPI device found. Use flashrom -p "
			 "linux_spi:dev=/dev/spidevX.Y\n");
		return 1;
	}

	p = extract_programmer_param("spispeed");
	if (p && strlen(p)) {
		speed_hz = (uint32_t)strtoul(p, &endp, 10) * 1000;
		if (p == endp || speed_hz == 0) {
			msg_perr("%s: invalid clock: %s kHz\n", __func__, p);
			return 1;
		}
	} else {
		msg_pinfo("Using default %"PRIu32
			  "kHz clock. Use 'spispeed' parameter to override.\n",
			  speed_hz / 1000);
	}

	msg_pdbg("Using device %s\n", dev);
	if ((fd = open(dev, O_RDWR)) == -1) {
		msg_perr("%s: failed to open %s: %s\n", __func__,
			 dev, strerror(errno));

		return 1;
	}

	if (register_shutdown(linux_spi_shutdown, NULL))
		return 1;
	/* We rely on the shutdown function for cleanup from here on. */

	if (ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed_hz) == -1) {
		msg_perr("%s: failed to set speed to %"PRIu32"Hz: %s\n",
			 __func__, speed_hz, strerror(errno));
		return 1;
	}
	msg_pdbg("Using %"PRIu32"kHz clock\n", speed_hz / 1000);

	if (ioctl(fd, SPI_IOC_WR_MODE, &mode) == -1) {
		msg_perr("%s: failed to set SPI mode to 0x%02x: %s\n",
			 __func__, mode, strerror(errno));
		return 1;
	}

	if (ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits) == -1) {
		msg_perr("%s: failed to set the number of bits per SPI word to %u: %s\n",
			 __func__, bits == 0 ? 8 : bits, strerror(errno));
		return 1;
	}

	/* Read max buffer size from sysfs, or use page size as fallback. */
	FILE *fp;
	fp = fopen(BUF_SIZE_FROM_SYSFS, "r");
	if (!fp) {
		msg_pwarn("Cannot open %s: %s.\n", BUF_SIZE_FROM_SYSFS, strerror(errno));
		goto out;
	}

	char buf[10];
	if (!fgets(buf, sizeof(buf), fp)) {
		if (feof(fp))
			msg_pwarn("Cannot read %s: file is empty.\n", BUF_SIZE_FROM_SYSFS);
		else
			msg_pwarn("Cannot read %s: %s.\n", BUF_SIZE_FROM_SYSFS, strerror(errno));
		goto out;
	}

	long int tmp;
	errno = 0;
	tmp = strtol(buf, NULL, 0);
	if ((tmp < 0) || errno) {
		msg_pwarn("Buffer size %ld from %s seems wrong.\n", tmp, BUF_SIZE_FROM_SYSFS);
	} else {
		msg_pdbg("%s: Using value from %s as max buffer size.\n", __func__, BUF_SIZE_FROM_SYSFS);
		max_kernel_buf_size = (size_t)tmp;
	}

out:
	if (fp)
		fclose(fp);

	if (!max_kernel_buf_size) {
		msg_pdbg("%s: Using page size as max buffer size.\n", __func__);
		max_kernel_buf_size = (size_t)getpagesize();
	}

	msg_pdbg("%s: max_kernel_buf_size: %zu\n", __func__, max_kernel_buf_size);
	register_spi_master(&spi_master_linux);
	return 0;
}

static int linux_spi_shutdown(void *data)
{
	if (fd != -1) {
		close(fd);
		fd = -1;
	}
	return 0;
}

static int linux_spi_send_command(const struct flashctx *flash, unsigned int writecnt,
				  unsigned int readcnt,
				  const unsigned char *txbuf,
				  unsigned char *rxbuf)
{
	int msg_start = 0, msg_count = 0;
	struct spi_ioc_transfer msg[2] = {
		{
			.tx_buf = (uint64_t)(uintptr_t)txbuf,
			.len = writecnt,
		},
		{
			.rx_buf = (uint64_t)(uintptr_t)rxbuf,
			.len = readcnt,
		},
	};

	if (fd == -1)
		return -1;

	/* Only pass necessary msg[] to ioctl() to avoid the empty message
	 * which drives an un-expected CS line and clocks. */
	if (writecnt) {
		msg_start = 0;  /* tx: msg[0] */
		msg_count++;
		if (readcnt) {
			msg_count++;
		}
	} else if (readcnt) {
		msg_start = 1;  /* rx: msg[1] */
		msg_count++;
	} else {
		msg_cerr("%s: both writecnt and readcnt are 0.\n",
			 __func__);
		return -1;
	}

	if (ioctl(fd, SPI_IOC_MESSAGE(msg_count), &msg[msg_start]) == -1) {
		msg_cerr("%s: ioctl: %s\n", __func__, strerror(errno));
		return -1;
	}
	return 0;
}

static int linux_spi_read(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len)
{
	/* Older kernels use a single buffer for combined input and output
	   data. So account for longest possible command + address, too. */
	return spi_read_chunked(flash, buf, start, len, max_kernel_buf_size - 5);
}

static int linux_spi_write_256(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len)
{
	/* 5 bytes must be reserved for longest possible command + address. */
	return spi_write_chunked(flash, buf, start, len, max_kernel_buf_size - 5);
}

#endif // CONFIG_LINUX_SPI == 1