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Introduce serialport_write_nonblock()

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It seems useful to have a generic and platform-independent method to
read and write to a serial port without blocking. This is the write part.

This allows to get rid of the explicit temporary disabling of blocking I/O in
serprog's sp_synchronize().

Corresponding to flashrom svn r1662.

Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
This commit is contained in:
Stefan Tauner
2013-04-01 00:45:45 +00:00
parent 00e1608501
commit ae3d83765c
3 changed files with 78 additions and 14 deletions
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19
serprog.c
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@ -117,23 +117,19 @@ static int sp_opensocket(char *ip, unsigned int port)
/* Synchronize: a bit tricky algorithm that tries to (and in my tests has *
* always succeeded in) bring the serial protocol to known waiting-for- *
* command state - uses nonblocking read - rest of the driver uses *
* command state - uses nonblocking I/O - rest of the driver uses *
* blocking read - TODO: add an alarm() timer for the rest of the app on *
* serial operations, though not such a big issue as the first thing to *
* do is synchronize (eg. check that device is alive). */
static int sp_synchronize(void)
{
int i;
int flags = fcntl(sp_fd, F_GETFL);
unsigned char buf[8];
flags |= O_NONBLOCK;
fcntl(sp_fd, F_SETFL, flags);
/* First sends 8 NOPs, then flushes the return data - should cause *
* the device serial parser to get to a sane state, unless if it *
* is waiting for a real long write-n. */
memset(buf, S_CMD_NOP, 8);
if (write(sp_fd, buf, 8) != 8) {
msg_perr("flush write: %s\n", strerror(errno));
if (serialport_write_nonblock(buf, 8, 1, NULL) != 0) {
goto err_out;
}
/* A second should be enough to get all the answers to the buffer */
@ -147,8 +143,7 @@ static int sp_synchronize(void)
for (i = 0; i < 8; i++) {
int n;
unsigned char c = S_CMD_SYNCNOP;
if (write(sp_fd, &c, 1) != 1) {
msg_perr("sync write: %s\n", strerror(errno));
if (serialport_write_nonblock(&c, 1, 1, NULL) != 0) {
goto err_out;
}
msg_pdbg(".");
@ -165,9 +160,8 @@ static int sp_synchronize(void)
if (ret > 0 || c != S_ACK)
continue;
c = S_CMD_SYNCNOP;
if (write(sp_fd, &c, 1) != 1) {
msg_perr("sync write: %s\n", strerror(errno));
return 1;
if (serialport_write_nonblock(&c, 1, 1, NULL) != 0) {
goto err_out;
}
ret = serialport_read_nonblock(&c, 1, 500, NULL);
if (ret < 0)
@ -179,9 +173,6 @@ static int sp_synchronize(void)
goto err_out;
if (c != S_ACK)
break; /* fail */
/* Ok, synchronized; back to blocking reads and return. */
flags &= ~O_NONBLOCK;
fcntl(sp_fd, F_SETFL, flags);
msg_pdbg("\n");
return 0;
}