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swd2.c
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swd2.c
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#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <termios.h>
#include <time.h>
#include <unistd.h>
// CLOCK_MONOTONIC_FAST is FreeBSD specific.
// Fall back to CLOCK_MONOTONIC_COARSE if available.
// If neither is available use CLOCK_MONOTONIC which will likely be implemented as syscall.
#ifndef CLOCK_MONOTONIC_FAST
#ifdef CLOCK_MONOTONIC_COARSE
#define CLOCK_MONOTONIC_FAST CLOCK_MONOTONIC_COARSE
#else
#define CLOCK_MONOTONIC_FAST CLOCK_MONOTONIC
#endif
#endif
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdocumentation-unknown-command"
#pragma clang diagnostic ignored "-Wpadded"
#include <stlink.h>
#pragma clang diagnostic pop
// An evil collection of global variables follows.
static uint32_t addr = 0; // the base address of the ring buffers
static stlink_t *handle = NULL; // handle to the ST/LINK V2
static struct termios orig[1]; // original terminal settings
static bool quit = false; // Quit the main loop
static bool reset = false; // Reset the target
static bool upload = false; // Upload wanted
static bool new_file = false; // Inject a file seperator?
static bool end_of_file = false; // Inject a end of medium?
static bool stdin_tty = false; // Is stdin a TTY?
static bool stdin_pipe = false; // Is stdin a pipe?
static bool stdin_file = false; // Is stdin a regular file?
static int fd = STDIN_FILENO;
static int line_num = -1;
// On TTYs ctrl+d results in a ASCII end of transmission control character.
#define ASCII_EOT (0x04)
#define ASCII_ACK (0x06)
#define ASCII_NAK (0x15)
#define ASCII_CAN (0x18)
#define ASCII_EM (0x19)
#define ASCII_FS (0x1c)
static void
__attribute__((noreturn))
__attribute__((format(printf, 1, 2)))
die(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wformat-nonliteral"
vfprintf(stderr, fmt, ap);
#pragma clang diagnostic pop
fputc('\n', stderr);
exit(1);
va_end(ap);
}
// Close the the ST/LINK V2 correctly.
static void
close_handle(void)
{
if ( handle ) {
stlink_close(handle);
handle = NULL;
}
}
// Open the first ST/LINK V2 connected via USB
// Register an atexit() handler to close it.
static stlink_t *
open_or_die(char serial[STLINK_SERIAL_BUFFER_SIZE])
{
enum ugly_loglevel loglevel = UERROR;
bool want_reset = false;
handle = stlink_open_usb(loglevel, want_reset, serial, STLINK_SWDCLK_4MHZ_DIVISOR);
if ( !handle ) {
die("Failed to open the debugger.");
}
atexit(close_handle);
stlink_set_swdclk(handle, 24000); // Run STLINK/V3 @ 24MHz
return handle;
}
// Set the ring buffer base address.
static void
set_addr_or_die(const char *hex_addr)
{
errno = 0;
long result = strtol(hex_addr, NULL, 16);
if ( errno ) {
die("Failed to convert base address: %s.", strerror(errno));
}
addr = (uint32_t)result;
}
// Read the ring buffer indicies from the microcontroller.
// All four indicies ({R, W} x {TX, RX}) are stored in a naturally aligned 32 bit word.
static uint32_t
read_indicies_or_die(void)
{
if ( stlink_read_mem32(handle, addr, 4) ) {
die("Failed to read the ringbuffer indicies.");
}
return ((uint32_t)handle->q_buf[0]) |
(((uint32_t)handle->q_buf[1]) << 8) |
(((uint32_t)handle->q_buf[2]) << 16) |
(((uint32_t)handle->q_buf[3]) << 24);
}
// Retry interrupted or blocked writes. Abort on I/O error.
static void
write_or_die(const void *buffer, size_t len)
{
const uint8_t *pos = buffer;
while ( len > 0 ) {
ssize_t delta = write(STDOUT_FILENO, pos, len);
if ( delta < 0 ) {
if ( errno == EAGAIN || errno == EINTR ) {
continue;
} else {
die("Failed to write to stdout.");
}
}
len -= (size_t)delta;
pos += delta;
}
}
// Write a buffer to the microcontroller 8 bit at a time. Abort on I/O error.
// Using write8_or_die() is slower than write32_or_die().
static void
write8_or_die(uint32_t destination, const void *source, uint16_t length_in_bytes)
{
const size_t buffer_size = Q_BUF_LEN;
if ( length_in_bytes > buffer_size ) {
die("Oversized bytewise write failed (length = %u, max = %zu).",
length_in_bytes, buffer_size);
}
memcpy(handle->q_buf, source, length_in_bytes);
if ( stlink_write_mem8(handle, destination, length_in_bytes) ) {
die("Bytewise write failed (destination = 0x%08x, length = %u).",
destination, length_in_bytes);
}
}
// Write a buffer to the microcontroll 32 bit at at time. Abort on I/O error.
// Length has to be a multiple of four.
// Using write32_or_die() is faster than write8_or_die().
static void
write32_or_die(uint32_t destination, const void *source, uint16_t length_in_bytes)
{
const size_t buffer_size = Q_BUF_LEN;
if ( length_in_bytes > buffer_size ) {
die("Oversized wordwise write failed (length = %u, max = %zu).",
length_in_bytes, buffer_size);
}
memcpy(handle->q_buf, source, length_in_bytes);
if ( stlink_write_mem32(handle, destination, length_in_bytes) ) {
die("Wordwise write failed (destination = 0x%08x, length = %u).",
destination, length_in_bytes);
}
}
static void
end_upload(void)
{
if ( fd != STDIN_FILENO ) {
close(fd);
fd = STDIN_FILENO;
}
if ( line_num >= 0 ) {
end_of_file = true;
}
}
static void
parse(uint8_t *reply, size_t len)
{
for ( size_t i = 0; i < len; i++ ) {
switch ( reply[i] ) {
// Allow the target to disconnect from the host
case ASCII_EOT:
quit = true;
break;
// Send by QUIT after each line
case ASCII_ACK:
if ( line_num >= 0 ) {
line_num++;
}
break;
// Contained in all compiler errors
case ASCII_NAK:
if ( line_num >= 0 ) {
fprintf(stderr, "\n*** Failure in line %i. ***\n", line_num);
}
end_upload();
break;
// Allow the target to cancel uploads
case ASCII_CAN:
end_upload();
break;
// Use end of medium as end of file marker
case ASCII_EM:
line_num = -1;
break;
// Begin each new file with file seperator marker
case ASCII_FS:
line_num = 0;
break;
}
}
}
// Consume everything enqueued by the microcontroller into the ringbuffers.
// The ring buffers are single producer single writer queues.
static bool
consume(uint32_t indicies)
{
uint8_t rx_w = (uint8_t)(indicies >> 16);
uint8_t rx_r = (uint8_t)(indicies >> 24);
uint8_t rx_u = rx_w - rx_r;
if ( !rx_u ) {
return false;
}
// Optimize reads:
// * Use as few commands as possible
// * Round down to 32 bit alignment
// * Pad to 32 bit alignment
// * The ring buffer can wrap around
const uint32_t start = rx_r;
const uint32_t off = start & 3;
const uint16_t len = rx_w > rx_r ? rx_u : (uint8_t)-rx_r;
const uint32_t start0 = start & -4u;
const uint32_t start1 = 0;
const uint16_t len0 = (uint16_t)(len + off + 3) & -4u;
const uint16_t len1 = (rx_u + 3 - len) & -4;
if ( len0 ) {
stlink_read_mem32(handle, addr + 4 + 256 + start0, len0);
write_or_die(handle->q_buf + off, len);
parse(handle->q_buf + off, len);
}
if ( len1 ) {
stlink_read_mem32(handle, addr + 4 + 256 + start1, len1);
write_or_die(handle->q_buf, rx_u - len);
parse(handle->q_buf, rx_u - len);
}
handle->q_buf[0] = rx_w;
if ( stlink_write_mem8(handle, addr + 3, 1) ) {
die("Failed to advance RX read index.");
}
return true;
}
// Attempt to read and enqueue as much input as possible to the microcontroller.
// The ring buffers are single producer single writer queues.
static bool
produce(uint32_t indicies)
{
uint8_t tx_w = (uint8_t)(indicies >> 0);
uint8_t tx_r = (uint8_t)(indicies >> 8);
uint8_t tx_f = 255 - (tx_w - tx_r);
uint8_t buffer[256];
uint8_t count = 0;
if ( !tx_f ) {
return false;
}
if ( new_file ) {
const char helper[] = "\x1c\n$1c emit\n";
if ( tx_f < strlen(helper) ) {
return false;
}
memcpy(buffer, helper, strlen(helper));
count = (uint8_t)strlen(helper);
new_file = false;
} else if ( end_of_file ) {
const char helper[] = "\x19\n$19 emit\n";
if ( tx_f < strlen(helper) ) {
return false;
}
memcpy(buffer, helper, strlen(helper));
count = (uint8_t)strlen(helper);
end_of_file = false;
} else {
ssize_t result = read(fd, buffer, tx_f);
if ( result < 0 ) {
if ( errno != EINTR && errno != EAGAIN ) {
die("Failed to read from stdin: %s.", strerror(errno));
} else {
return false;
}
}
count = (uint8_t)result;
}
if ( !count ) {
if ( fd != STDIN_FILENO ) {
end_upload();
} else {
quit = true;
}
}
// On TTYs EOF is signaled with a ASCII end of transmission control character.
if ( stdin_tty && fd == STDIN_FILENO ) {
const uint8_t *eof = memchr(buffer, ASCII_EOT, count);
if ( eof ) {
count = (uint8_t)(eof - buffer);
quit = true;
}
}
// Optimize writes:
// * The buffer is word aligned
// * Start with 8 bit writes if necessary until 32 bit alignment is reached
// * Use as many 32 bit where possible
// * Finish with 8 bit writes if necessary
// * The ring buffer can wrap around
bool carry = (tx_w + count) >> 8;
uint8_t len1 = carry ? tx_w + count : 0;
uint8_t len0 = count - len1;
uint8_t byte0 = (-tx_w & 3) > len0 ? len0 : -tx_w & 3;
uint8_t byte1 = (len0 - byte0) % 4;
uint8_t byte2 = len1 % 4;
uint8_t word0 = len0 - byte0 - byte1;
uint8_t word1 = len1 - byte2;
uint8_t *input = buffer;
uint32_t output = addr + 4 + tx_w;
if ( byte0 ) {
write8_or_die(output, input, byte0);
input += byte0; output += byte0;
}
if ( word0 ) {
write32_or_die(output, input, word0);
input += word0; output += word0;
}
if ( byte1 ) {
write8_or_die(output, input, byte1);
input += byte1;
}
output = addr + 4;
if ( word1 ) {
write32_or_die(output, input, word1);
input += word1; output += word1;
}
if ( byte2 ) {
write8_or_die(output, input, byte2);
}
handle->q_buf[0] = tx_w + count;
if ( stlink_write_mem8(handle, addr + 0, 1) ) {
die("Failed to advance TX write index.");
}
return true;
}
// The atexit(3) callback used by raw_mode_or_die()
static void
restore_stdin(void)
{
tcsetattr(STDIN_FILENO, TCSAFLUSH, orig);
}
// Put the standard input into raw mode if it's a TTY.
// Restore stdin to its previous mode on exit.
//
// TTYs have to be but into raw mode because in canonical
// mode lines are buffered and the forth system expects
// unbuffered input.
static void
raw_mode_or_die(void)
{
if ( !stdin_tty ) {
return;
}
if ( tcgetattr(STDIN_FILENO, orig) ) {
die("Failed to get TTY attributes.");
}
atexit(restore_stdin);
struct termios raw = *orig;
raw.c_lflag &= (unsigned)~(ECHO | ICANON);
if ( tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw) ) {
die("Failed to put terminal into raw mode: %s.", strerror(errno));
}
}
// Calculate the difference between two timespecs.
static struct timespec
elapsed(struct timespec start, struct timespec stop)
{
if ( stop.tv_nsec - start.tv_nsec < 0 ) {
struct timespec result = {
.tv_sec = stop.tv_sec - start.tv_sec - 1,
.tv_nsec = stop.tv_nsec - start.tv_nsec + 1000000000
};
return result;
} else {
struct timespec result = {
.tv_sec = stop.tv_sec - start.tv_sec,
.tv_nsec = stop.tv_nsec - start.tv_nsec
};
return result;
}
}
// Put stdin into non blocking more or die trying.
//
// The protocol between STLINK/V2 and target and between
// the host PC and the STLINK/V2 both assume polling.
// Blocking on stdin would block transmissions from the
// target to the host PC as well.
static void
stdin_nonblock_or_die(void)
{
errno = 0;
int flags = fcntl(STDIN_FILENO, F_GETFL, 0);
if ( errno ) {
die("Failed to get file descriptor status flags: %s.", strerror(errno));
}
if ( fcntl(STDIN_FILENO, F_SETFL, flags | O_NONBLOCK) == -1 ) {
die("Failed to add O_NONBLOCK to file descriptor status flags: %s.", strerror(errno));
}
}
// Retrieve the current clock value
static struct timespec
get_time(void)
{
struct timespec ts;
// No error handling required because reading valid clocks always succeeds.
clock_gettime(CLOCK_MONOTONIC_FAST, &ts);
return ts;
}
// Decode the ring buffer indicies to stderr.
//
// Calculates how much is free/used in each direction.
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunused-function"
static void __attribute__((unused))
debug_indicies(uint32_t indicies)
{
#pragma clang diagnostic pop
uint8_t tx_w = (uint8_t)(indicies >> 0);
uint8_t tx_r = (uint8_t)(indicies >> 8);
uint8_t rx_w = (uint8_t)(indicies >> 16);
uint8_t rx_r = (uint8_t)(indicies >> 24);
uint8_t rx_u = rx_w - rx_r;
uint8_t tx_f = 255 - (tx_w - tx_r);
fprintf(stderr, "\nTX: r = %i, w = %i, f = %i RX: r = %i, w = %i, u = %i\n",
tx_r, tx_w, tx_f, rx_r, rx_w, rx_u);
}
// Find out if stdin is a TTY or something else.
//
// Refuses files that aren't TTYs, pipes or regular files.
static void
stdin_file_type_or_die(void)
{
struct stat sb;
if ( fstat(STDIN_FILENO, &sb) ) {
die("Failed to fstat() stdin: %s.", strerror(errno));
}
const mode_t file_type = sb.st_mode & S_IFMT;
switch ( file_type ) {
case S_IFIFO:
stdin_pipe = true;
break;
case S_IFCHR:
stdin_tty = isatty(STDIN_FILENO);
if ( !stdin_tty ) {
die("TTYs are the only supported kind of character device.");
}
break;
case S_IFREG:
stdin_file = true;
break;
default:
die("unsupported file type: 0%o.", file_type);
}
}
// Terminate the main loop by setting the quit flag.
static void
handler_term(int sig)
{
(void)sig;
quit = true;
}
// Schedule the target to be reset.
static void
handler_int(int sig)
{
(void)sig;
reset = true;
}
static void
handler_quit(int sig)
{
(void)sig;
upload = true;
}
// Register signal handlers for SIGINT and SIGTERM.
// The signal handlers terminate the main loop.
static void
install_signal_handlers(void)
{
struct sigaction action[1] = {{ .sa_handler = handler_int }};
sigemptyset(&action->sa_mask);
sigaction(SIGINT, action, NULL);
action->sa_handler = handler_term;
sigaction(SIGTERM, action, NULL);
action->sa_handler = handler_quit;
sigaction(SIGQUIT, action, NULL);
}
int
main(int argc, char *argv[])
{
// We need to know the base address of the ring buffer pair
// on the target.
//
// Allow the user to skip automatic detection by providing the address.
char * serial = NULL;
switch ( argc ) {
case 1:
break;
case 2:
set_addr_or_die(argv[1]);
break;
case 3:
set_addr_or_die(argv[1]);
serial = argv[2];
printf("\033]2;swd2 : %s\007", serial);
fflush(stdout);
break;
default:
fprintf(stderr, "usage: %s [<base-addr> [<serial>]]\n", argv[0]);
return 64;
}
// Required setup code. Abort on all errors.
stdin_file_type_or_die();
install_signal_handlers();
open_or_die(serial);
raw_mode_or_die();
stdin_nonblock_or_die();
// Halt the target to read the base address from R11.
if ( !addr ) {
if ( stlink_force_debug(handle) ) {
die("Failed to halt the target.");
}
struct stlink_reg regs[1];
if ( stlink_read_reg(handle, 11, regs) ) {
die("Failed to registers.");
}
if ( stlink_run(handle, RUN_NORMAL) ) {
die("Failed to resume the target.");
}
addr = regs->r[11];
}
struct timespec last_active = get_time();
while ( !quit ) {
uint32_t indicies = read_indicies_or_die();
bool rx_active = consume(indicies);
bool tx_active = produce(indicies);
bool active = rx_active | tx_active;
struct timespec now = get_time();
if ( reset ) {
if ( stlink_reset(handle, RESET_HARD) ) {
die("Failed to reset target.");
}
if ( stlink_run(handle, RUN_NORMAL) ) {
die("Failed to resume target.");
}
fprintf(stderr, "\nRESET\n");
reset = false;
}
if ( upload && fd == STDIN_FILENO ) {
fd = open("upload.fs", O_RDONLY);
if ( fd < 0 ) {
fprintf(stderr, "*** Failed to open \"upload.fs\": %s. ***\n", strerror(errno));
fd = STDIN_FILENO;
}
new_file = true;
active = true;
upload = false;
}
// Reduce polling rate after a period of inactivity saving CPU cycles and power.
if ( active ) {
last_active = now;
} else {
struct timespec diff = elapsed(last_active, now);
if ( diff.tv_sec || diff.tv_nsec > 100000000 ) {
usleep(10*1000);
}
}
}
return 0;
}