programmer: Add bitbanging programmer driver for Linux libgpiod
With this driver, any single board computer, old smartphone, etc. with
a few spare GPIOs can be used for flashrom.
Tested by reading of a 2048 kB flash chip on a Qualcomm MSM8916 SoC
@800 MHz, ran the following command:
time flashrom -p linux_gpiod:gpiochip=0,cs=18,sck=19,mosi=13,miso=56 -r test.bin
This command uses /dev/gpiochip0 with the specified GPIO numbers for the
SPI lines. All arguments are mandatory.
Output:
[...]
Found GigaDevice flash chip "GD25LQ16" (2048 kB, SPI) on linux_gpiod.
[...]
real 1m 33.96s
Change-Id: Icad3eb7764f28feaea51bda3a7893da724c86d06
Signed-off-by: Steve Markgraf <steve@steve-m.de>
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/flashrom-stable/+/73290
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/linux_gpio_spi.c b/linux_gpio_spi.c
new file mode 100644
index 0000000..0103d19
--- /dev/null
+++ b/linux_gpio_spi.c
@@ -0,0 +1,183 @@
+/*
+ * This file is part of the flashrom project.
+ *
+ * Copyright (C) 2023 Steve Markgraf <steve@steve-m.de>
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+#include <errno.h>
+#include <gpiod.h>
+#include "programmer.h"
+#include "spi.h"
+#include "flash.h"
+
+#define CONSUMER "flashrom"
+
+struct linux_gpio_spi {
+ struct gpiod_chip *chip;
+ struct gpiod_line_bulk bulk;
+ struct gpiod_line *cs_line, *sck_line, *mosi_line, *miso_line;
+};
+
+static void linux_gpio_spi_bitbang_set_cs(int val, void *spi_data)
+{
+ struct linux_gpio_spi *data = spi_data;
+ if (gpiod_line_set_value(data->cs_line, val) < 0)
+ msg_perr("Setting cs line failed\n");
+}
+
+static void linux_gpio_spi_bitbang_set_sck(int val, void *spi_data)
+{
+ struct linux_gpio_spi *data = spi_data;
+ if (gpiod_line_set_value(data->sck_line, val) < 0)
+ msg_perr("Setting sck line failed\n");
+}
+
+static void linux_gpio_spi_bitbang_set_mosi(int val, void *spi_data)
+{
+ struct linux_gpio_spi *data = spi_data;
+ if (gpiod_line_set_value(data->mosi_line, val) < 0)
+ msg_perr("Setting sck line failed\n");
+}
+
+static int linux_gpio_spi_bitbang_get_miso(void *spi_data)
+{
+ struct linux_gpio_spi *data = spi_data;
+ int r = gpiod_line_get_value(data->miso_line);
+ if (r < 0)
+ msg_perr("Getting miso line failed\n");
+ return r;
+}
+
+static const struct bitbang_spi_master bitbang_spi_master_gpiod = {
+ .set_cs = linux_gpio_spi_bitbang_set_cs,
+ .set_sck = linux_gpio_spi_bitbang_set_sck,
+ .set_mosi = linux_gpio_spi_bitbang_set_mosi,
+ .get_miso = linux_gpio_spi_bitbang_get_miso,
+};
+
+static int linux_gpio_spi_shutdown(void *spi_data)
+{
+ struct linux_gpio_spi *data = spi_data;
+
+ if (gpiod_line_bulk_num_lines(&data->bulk) > 0)
+ gpiod_line_release_bulk(&data->bulk);
+
+ if (data->chip)
+ gpiod_chip_close(data->chip);
+
+ free(data);
+
+ return 0;
+}
+
+static int linux_gpio_spi_init(void)
+{
+ struct linux_gpio_spi *data = NULL;
+ struct gpiod_chip *chip = NULL;
+ const char *param_str[] = { "cs", "sck", "mosi", "miso", "gpiochip" };
+ const bool param_required[] = { true, true, true, true, false };
+ unsigned int param_int[ARRAY_SIZE(param_str)];
+ unsigned int i;
+ int r;
+
+ data = calloc(1, sizeof(*data));
+ if (!data) {
+ msg_perr("Unable to allocate space for SPI master data\n");
+ return 1;
+ }
+
+ for (i = 0; i < ARRAY_SIZE(param_str); i++) {
+ char *param = extract_programmer_param(param_str[i]);
+ char *endptr;
+ r = 1;
+
+ if (param) {
+ errno = 0;
+ param_int[i] = strtoul(param, &endptr, 10);
+ r = (*endptr != '\0') || (errno != 0);
+ free(param);
+ } else {
+ param_int[i] = UINT_MAX;
+ }
+
+ if ((param_required[i] || param) && r) {
+ msg_perr("Missing or invalid required programmer "
+ "parameter %s=<n>\n", param_str[i]);
+ goto err_exit;
+ }
+ }
+
+ char *const dev = extract_programmer_param("dev");
+ if (!dev && param_int[4] == UINT_MAX) {
+ msg_perr("Either a 'dev' or 'gpiochip' parameter must be specified.\n");
+ goto err_exit;
+ }
+ if (dev && param_int[4] != UINT_MAX) {
+ msg_perr("Only one of 'dev' or 'gpiochip' parameters can be specified.\n");
+ free(dev);
+ goto err_exit;
+ }
+
+ if (dev) {
+ chip = gpiod_chip_open(dev);
+ free(dev);
+ } else {
+ chip = gpiod_chip_open_by_number(param_int[4]);
+ }
+ if (!chip) {
+ msg_perr("Failed to open gpiochip: %s\n", strerror(errno));
+ goto err_exit;
+ }
+
+ data->chip = chip;
+
+ if (gpiod_chip_get_lines(chip, param_int, 4, &data->bulk)) {
+ msg_perr("Error getting GPIO lines\n");
+ goto err_exit;
+ }
+
+ data->cs_line = gpiod_line_bulk_get_line(&data->bulk, 0);
+ data->sck_line = gpiod_line_bulk_get_line(&data->bulk, 1);
+ data->mosi_line = gpiod_line_bulk_get_line(&data->bulk, 2);
+ data->miso_line = gpiod_line_bulk_get_line(&data->bulk, 3);
+
+ r = gpiod_line_request_output(data->cs_line, CONSUMER, 1);
+ r |= gpiod_line_request_output(data->sck_line, CONSUMER, 1);
+ r |= gpiod_line_request_output(data->mosi_line, CONSUMER, 1);
+ r |= gpiod_line_request_input(data->miso_line, CONSUMER);
+
+ if (r < 0) {
+ msg_perr("Requesting GPIO lines failed\n");
+ goto err_exit;
+ }
+
+ if (register_shutdown(linux_gpio_spi_shutdown, data))
+ goto err_exit;
+
+ /* shutdown function does the cleanup */
+ return register_spi_bitbang_master(&bitbang_spi_master_gpiod, data);
+
+err_exit:
+ linux_gpio_spi_shutdown(data);
+ return 1;
+}
+
+const struct programmer_entry programmer_linux_gpio_spi = {
+ .name = "linux_gpio_spi",
+ .type = OTHER,
+ .devs.note = "Device file /dev/gpiochip<n>\n",
+ .init = linux_gpio_spi_init,
+};