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/*
* This file is part of the flashrom project.
*
* Copyright (C) 2018 Linaro Limited
*
* 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.
*/
/*
* Bit bang driver for the 96Boards Developerbox (a.k.a. Synquacer E-series)
* on-board debug UART. The Developerbox implements its debug UART using a
* CP2102N, a USB to UART bridge which also provides four GPIO pins. On
* Developerbox these can be hooked up to the onboard SPI NOR FLASH and used
* for emergency de-brick without any additional hardware programmer. Bit
* banging over USB is extremely slow compared to a proper SPI programmer so
* this is only practical as a de-brick tool.
*
* Schematic is available here:
* https://www.96boards.org/documentation/enterprise/developerbox/hardware-docs/
*
* To prepare a Developerbox for programming via the debug UART, DSW4 must be
* changed from the default 00000000 to 10001000 (i.e. DSW4-1 and DSW4-5
* should be turned on).
*/
#include "platform.h"
#include <stdlib.h>
#include <libusb.h>
#include "programmer.h"
#include "spi.h"
/* Bit positions for each pin. */
#define DEVELOPERBOX_SPI_SCK 0
#define DEVELOPERBOX_SPI_CS 1
#define DEVELOPERBOX_SPI_MISO 2
#define DEVELOPERBOX_SPI_MOSI 3
/* Config request types */
#define REQTYPE_HOST_TO_DEVICE 0x40
#define REQTYPE_DEVICE_TO_HOST 0xc0
/* Config request codes */
#define CP210X_VENDOR_SPECIFIC 0xff
/* CP210X_VENDOR_SPECIFIC */
#define CP210X_WRITE_LATCH 0x37e1
#define CP210X_READ_LATCH 0x00c2
const struct dev_entry devs_developerbox_spi[] = {
{0x10c4, 0xea60, OK, "Silicon Labs", "CP2102N USB to UART Bridge Controller"},
{0},
};
static struct libusb_context *usb_ctx;
static libusb_device_handle *cp210x_handle;
static int cp210x_gpio_get(void)
{
int res;
uint8_t gpio;
res = libusb_control_transfer(cp210x_handle, REQTYPE_DEVICE_TO_HOST,
CP210X_VENDOR_SPECIFIC, CP210X_READ_LATCH,
0, &gpio, 1, 0);
if (res < 0) {
msg_perr("Failed to read GPIO pins (%s)\n", libusb_error_name(res));
return 0;
}
return gpio;
}
static void cp210x_gpio_set(uint8_t val, uint8_t mask)
{
int res;
uint16_t gpio;
gpio = ((val & 0xf) << 8) | (mask & 0xf);
/* Set relay state on the card */
res = libusb_control_transfer(cp210x_handle, REQTYPE_HOST_TO_DEVICE,
CP210X_VENDOR_SPECIFIC, CP210X_WRITE_LATCH,
gpio, NULL, 0, 0);
if (res < 0)
msg_perr("Failed to read GPIO pins (%s)\n", libusb_error_name(res));
}
static void cp210x_bitbang_set_cs(int val)
{
cp210x_gpio_set(val << DEVELOPERBOX_SPI_CS, 1 << DEVELOPERBOX_SPI_CS);
}
static void cp210x_bitbang_set_sck(int val)
{
cp210x_gpio_set(val << DEVELOPERBOX_SPI_SCK, 1 << DEVELOPERBOX_SPI_SCK);
}
static void cp210x_bitbang_set_mosi(int val)
{
cp210x_gpio_set(val << DEVELOPERBOX_SPI_MOSI, 1 << DEVELOPERBOX_SPI_MOSI);
}
static int cp210x_bitbang_get_miso(void)
{
return !!(cp210x_gpio_get() & (1 << DEVELOPERBOX_SPI_MISO));
}
static void cp210x_bitbang_set_sck_set_mosi(int sck, int mosi)
{
cp210x_gpio_set(sck << DEVELOPERBOX_SPI_SCK | mosi << DEVELOPERBOX_SPI_MOSI,
1 << DEVELOPERBOX_SPI_SCK | 1 << DEVELOPERBOX_SPI_MOSI);
}
static const struct bitbang_spi_master bitbang_spi_master_cp210x = {
.set_cs = cp210x_bitbang_set_cs,
.set_sck = cp210x_bitbang_set_sck,
.set_mosi = cp210x_bitbang_set_mosi,
.get_miso = cp210x_bitbang_get_miso,
.set_sck_set_mosi = cp210x_bitbang_set_sck_set_mosi,
};
static int developerbox_spi_shutdown(void *data)
{
libusb_close(cp210x_handle);
libusb_exit(usb_ctx);
return 0;
}
int developerbox_spi_init(void)
{
libusb_init(&usb_ctx);
if (!usb_ctx) {
msg_perr("Could not initialize libusb!\n");
return 1;
}
char *serialno = extract_programmer_param("serial");
if (serialno)
msg_pdbg("Looking for serial number commencing %s\n", serialno);
cp210x_handle = usb_dev_get_by_vid_pid_serial(usb_ctx,
devs_developerbox_spi[0].vendor_id, devs_developerbox_spi[0].device_id, serialno);
free(serialno);
if (!cp210x_handle) {
msg_perr("Could not find a Developerbox programmer on USB.\n");
goto err_exit;
}
if (register_shutdown(developerbox_spi_shutdown, NULL))
goto err_exit;
if (register_spi_bitbang_master(&bitbang_spi_master_cp210x))
goto err_exit;
return 0;
err_exit:
libusb_exit(usb_ctx);
return 1;
}
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