svn commit: r324590 - head/usr.sbin/i2c

[Andriy Gapon]

Author: avg
Date: Fri Oct 13 09:21:41 2017
New Revision: 324590
URL: https://svnweb.freebsd.org/changeset/base/324590

Log:
  i2c(8): clean up and clarify read operation
  
  The code went to a lot of trouble to issue either a start+stop condition
  or a repeated start condition only to follow it with a stop condition
  and a read(2) call that issues a new start condition.
  So, fix the read in I2C_MODE_REPEATED_START mode by using I2CREAD ioctl
  within the running transaction.  This obviously requires that the slave
  address has the read bit set which was not required before.
  
  Another problem was with width parameter of zero and
  I2C_MODE_REPEATED_START mode.  In that case we issued a repeated start
  without any preceding start.
  
  While here, remove the redundant (unused) argument to I2CSTOP throughout
  the program.
  Also, clarify the meaning of -w option, especially "-w 0", in the manual
  page.
  
  Reviewed by:	no one
  Differential Revision: https://reviews.freebsd.org/D12331

Modified:
  head/usr.sbin/i2c/i2c.8
  head/usr.sbin/i2c/i2c.c

Modified: head/usr.sbin/i2c/i2c.8
==============================================================================
--- head/usr.sbin/i2c/i2c.8	Fri Oct 13 09:14:05 2017	(r324589)
+++ head/usr.sbin/i2c/i2c.8	Fri Oct 13 09:21:41 2017	(r324590)
@@ -83,6 +83,10 @@ using selected addresses 'a:b:c'. This option is avail
 used.
 .It Fl o Ar offset
 offset within the device for data transfer (hex).
+The default is zero.
+Use
+.Dq -w 0
+to disable writing of the offset to the slave.
 .It Fl r
 reset the controller.
 .It Fl s
@@ -91,6 +95,12 @@ scan the bus for devices.
 be verbose.
 .It Fl w Ar 0|8|16
 device addressing width (in bits).
+This is used to determine how to pass
+.Ar offset
+specified with
+.Fl o
+to the slave.
+Zero means that the offset is ignored and not passed to the slave at all.
 .El
 .Sh WARNINGS
 Great care must be taken when manipulating slave I2C devices with the

Modified: head/usr.sbin/i2c/i2c.c
==============================================================================
--- head/usr.sbin/i2c/i2c.c	Fri Oct 13 09:14:05 2017	(r324589)
+++ head/usr.sbin/i2c/i2c.c	Fri Oct 13 09:21:41 2017	(r324590)
@@ -212,15 +212,14 @@ start_over:
 				use_read_xfer = 1;
 				goto start_over;
 			}
-			cmd.slave = i << 1;
-			cmd.last = 1;
-			ioctl(fd, I2CSTOP, &cmd);
+			ioctl(fd, I2CSTOP);
 		}
 		if (error == 0) {
 			++num_found;
 			printf("%02x ", i);
 		}
 	}
+
 	/*
 	 * If we found nothing, maybe START is not supported and returns a
 	 * generic error code such as EIO or ENXIO, so try again using reads.
@@ -355,7 +354,7 @@ i2c_write(char *dev, struct options i2c_opt, char *i2c
 			}
 		}
 
-		error = ioctl(fd, I2CSTOP, &cmd);
+		error = ioctl(fd, I2CSTOP);
 		if (error == -1) {
 			err_msg = "ioctl: error sending stop condition";
 			goto err2;
@@ -439,8 +438,7 @@ i2c_write(char *dev, struct options i2c_opt, char *i2c
 		}
 		break;
 	}
-	cmd.slave = i2c_opt.addr;
-	error = ioctl(fd, I2CSTOP, &cmd);
+	error = ioctl(fd, I2CSTOP);
 	if (error == -1) {
 		err_msg = "ioctl: error sending stop condition";
 		goto err2;
@@ -450,8 +448,7 @@ i2c_write(char *dev, struct options i2c_opt, char *i2c
 	return (0);
 
 err1:
-	cmd.slave = i2c_opt.addr;
-	error = ioctl(fd, I2CSTOP, &cmd);
+	error = ioctl(fd, I2CSTOP);
 	if (error == -1)
 		fprintf(stderr, "error sending stop condition\n");
 err2:
@@ -466,7 +463,7 @@ static int
 i2c_read(char *dev, struct options i2c_opt, char *i2c_buf)
 {
 	struct iiccmd cmd;
-	int i, fd, error, bufsize;
+	int fd, error, bufsize;
 	char *err_msg, data = 0, *buf;
 
 	fd = open(dev, O_RDWR);
@@ -503,23 +500,22 @@ i2c_read(char *dev, struct options i2c_opt, char *i2c_
 		}
 
 		if (i2c_opt.mode == I2C_MODE_STOP_START) {
-			cmd.slave = i2c_opt.addr;
-			error = ioctl(fd, I2CSTOP, &cmd);
+			error = ioctl(fd, I2CSTOP);
 			if (error == -1) {
 				err_msg = "error sending stop condition";
 				goto err2;
 			}
 		}
 	}
-	cmd.slave = i2c_opt.addr;
+	cmd.slave = i2c_opt.addr | 1;
 	cmd.count = 1;
 	cmd.last = 0;
 	cmd.buf = &data;
-	if (i2c_opt.mode == I2C_MODE_STOP_START) {
+	if (i2c_opt.mode == I2C_MODE_STOP_START || i2c_opt.width == 0) {
 		error = ioctl(fd, I2CSTART, &cmd);
 		if (error == -1) {
 			err_msg = "ioctl: error sending start condition";
-			goto err1;
+			goto err2;
 		}
 	} else if (i2c_opt.mode == I2C_MODE_REPEATED_START) {
 		error = ioctl(fd, I2CRPTSTART, &cmd);
@@ -529,26 +525,27 @@ i2c_read(char *dev, struct options i2c_opt, char *i2c_
 			goto err1;
 		}
 	}
-	error = ioctl(fd, I2CSTOP, &cmd);
+
+	cmd.count = i2c_opt.count;
+	cmd.buf = i2c_buf;
+	cmd.last = 1;
+	error = ioctl(fd, I2CREAD, &cmd);
 	if (error == -1) {
-		err_msg = "error sending stop condition";
-		goto err2;
+		err_msg = "ioctl: error while reading";
+		goto err1;
 	}
 
-	for (i = 0; i < i2c_opt.count; i++) {
-		error = read(fd, &i2c_buf[i], 1);
-		if (error == -1) {
-			err_msg = "ioctl: error while reading";
-			goto err1;
-		}
+	error = ioctl(fd, I2CSTOP);
+	if (error == -1) {
+		err_msg = "error sending stop condtion\n";
+		goto err2;
 	}
 
 	close(fd);
 	return (0);
 
 err1:
-	cmd.slave = i2c_opt.addr;
-	error = ioctl(fd, I2CSTOP, &cmd);
+	error = ioctl(fd, I2CSTOP);
 	if (error == -1)
 		fprintf(stderr, "error sending stop condition\n");
 err2: