Merge branch 'i2c-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jdelvare/staging

Pull i2c updates from Jean Delvare.

* 'i2c-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jdelvare/staging:
  i2c: Split I2C_M_NOSTART support out of I2C_FUNC_PROTOCOL_MANGLING
  i2c-dev: Add support for I2C_M_RECV_LEN

10 files changed, 51 insertions, 14 deletions

diff --git a/Documentation/i2c/functionality b/Documentation/i2c/functionality
index 42c17c1fb3cd..b0ff2ab596ce 100644
--- a/Documentation/i2c/functionality
+++ b/Documentation/i2c/functionality
@@ -18,9 +18,9 @@ For the most up-to-date list of functionality constants, please check
                                   adapters typically can not do these)
   I2C_FUNC_10BIT_ADDR             Handles the 10-bit address extensions
   I2C_FUNC_PROTOCOL_MANGLING      Knows about the I2C_M_IGNORE_NAK,
-                                  I2C_M_REV_DIR_ADDR, I2C_M_NOSTART and
-                                  I2C_M_NO_RD_ACK flags (which modify the
-                                  I2C protocol!)
+                                  I2C_M_REV_DIR_ADDR and I2C_M_NO_RD_ACK
+                                  flags (which modify the I2C protocol!)
+  I2C_FUNC_NOSTART                Can skip repeated start sequence
   I2C_FUNC_SMBUS_QUICK            Handles the SMBus write_quick command
   I2C_FUNC_SMBUS_READ_BYTE        Handles the SMBus read_byte command
   I2C_FUNC_SMBUS_WRITE_BYTE       Handles the SMBus write_byte command
@@ -50,6 +50,9 @@ A few combinations of the above flags are also defined for your convenience:
                                   emulated by a real I2C adapter (using
                                   the transparent emulation layer)
 
+In kernel versions prior to 3.5 I2C_FUNC_NOSTART was implemented as
+part of I2C_FUNC_PROTOCOL_MANGLING.
+
 
 ADAPTER IMPLEMENTATION
 ----------------------
diff --git a/Documentation/i2c/i2c-protocol b/Documentation/i2c/i2c-protocol
index 10518dd58814..0b3e62d1f77a 100644
--- a/Documentation/i2c/i2c-protocol
+++ b/Documentation/i2c/i2c-protocol
@@ -49,7 +49,9 @@ a byte read, followed by a byte write:
 Modified transactions
 =====================
 
-We have found some I2C devices that needs the following modifications:
+The following modifications to the I2C protocol can also be generated,
+with the exception of I2C_M_NOSTART these are usually only needed to
+work around device issues:
 
   Flag I2C_M_NOSTART: 
     In a combined transaction, no 'S Addr Wr/Rd [A]' is generated at some
@@ -60,6 +62,11 @@ We have found some I2C devices that needs the following modifications:
     we do not generate Addr, but we do generate the startbit S. This will
     probably confuse all other clients on your bus, so don't try this.
 
+    This is often used to gather transmits from multiple data buffers in
+    system memory into something that appears as a single transfer to the
+    I2C device but may also be used between direction changes by some
+    rare devices.
+
   Flags I2C_M_REV_DIR_ADDR
     This toggles the Rd/Wr flag. That is, if you want to do a write, but
     need to emit an Rd instead of a Wr, or vice versa, you set this
diff --git a/drivers/base/regmap/regmap-i2c.c b/drivers/base/regmap/regmap-i2c.c
index 5f6b2478bf17..fa6bf5279d28 100644
--- a/drivers/base/regmap/regmap-i2c.c
+++ b/drivers/base/regmap/regmap-i2c.c
@@ -42,7 +42,7 @@ static int regmap_i2c_gather_write(void *context,
 	/* If the I2C controller can't do a gather tell the core, it
 	 * will substitute in a linear write for us.
 	 */
-	if (!i2c_check_functionality(i2c->adapter, I2C_FUNC_PROTOCOL_MANGLING))
+	if (!i2c_check_functionality(i2c->adapter, I2C_FUNC_NOSTART))
 		return -ENOTSUPP;
 
 	xfer[0].addr = i2c->addr;
diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c
index 7f0b83219744..fad22b0bb5b0 100644
--- a/drivers/i2c/algos/i2c-algo-bit.c
+++ b/drivers/i2c/algos/i2c-algo-bit.c
@@ -608,7 +608,7 @@ bailout:
 
 static u32 bit_func(struct i2c_adapter *adap)
 {
-	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
+	return I2C_FUNC_I2C | I2C_FUNC_NOSTART | I2C_FUNC_SMBUS_EMUL |
 	       I2C_FUNC_SMBUS_READ_BLOCK_DATA |
 	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
 	       I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
diff --git a/drivers/i2c/busses/i2c-nuc900.c b/drivers/i2c/busses/i2c-nuc900.c
index 03b615778887..a26dfb8cd586 100644
--- a/drivers/i2c/busses/i2c-nuc900.c
+++ b/drivers/i2c/busses/i2c-nuc900.c
@@ -502,7 +502,8 @@ static int nuc900_i2c_xfer(struct i2c_adapter *adap,
 /* declare our i2c functionality */
 static u32 nuc900_i2c_func(struct i2c_adapter *adap)
 {
-	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART |
+		I2C_FUNC_PROTOCOL_MANGLING;
 }
 
 /* i2c bus registration info */
diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
index fa0b13490873..01959154572d 100644
--- a/drivers/i2c/busses/i2c-s3c2410.c
+++ b/drivers/i2c/busses/i2c-s3c2410.c
@@ -626,7 +626,8 @@ static int s3c24xx_i2c_xfer(struct i2c_adapter *adap,
 /* declare our i2c functionality */
 static u32 s3c24xx_i2c_func(struct i2c_adapter *adap)
 {
-	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART |
+		I2C_FUNC_PROTOCOL_MANGLING;
 }
 
 /* i2c bus registration info */
diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index 45048323b75e..5ec2261574ec 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -265,19 +265,41 @@ static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client,
 
 	res = 0;
 	for (i = 0; i < rdwr_arg.nmsgs; i++) {
-		/* Limit the size of the message to a sane amount;
-		 * and don't let length change either. */
-		if ((rdwr_pa[i].len > 8192) ||
-		    (rdwr_pa[i].flags & I2C_M_RECV_LEN)) {
+		/* Limit the size of the message to a sane amount */
+		if (rdwr_pa[i].len > 8192) {
 			res = -EINVAL;
 			break;
 		}
+
 		data_ptrs[i] = (u8 __user *)rdwr_pa[i].buf;
 		rdwr_pa[i].buf = memdup_user(data_ptrs[i], rdwr_pa[i].len);
 		if (IS_ERR(rdwr_pa[i].buf)) {
 			res = PTR_ERR(rdwr_pa[i].buf);
 			break;
 		}
+
+		/*
+		 * If the message length is received from the slave (similar
+		 * to SMBus block read), we must ensure that the buffer will
+		 * be large enough to cope with a message length of
+		 * I2C_SMBUS_BLOCK_MAX as this is the maximum underlying bus
+		 * drivers allow. The first byte in the buffer must be
+		 * pre-filled with the number of extra bytes, which must be
+		 * at least one to hold the message length, but can be
+		 * greater (for example to account for a checksum byte at
+		 * the end of the message.)
+		 */
+		if (rdwr_pa[i].flags & I2C_M_RECV_LEN) {
+			if (!(rdwr_pa[i].flags & I2C_M_RD) ||
+			    rdwr_pa[i].buf[0] < 1 ||
+			    rdwr_pa[i].len < rdwr_pa[i].buf[0] +
+					     I2C_SMBUS_BLOCK_MAX) {
+				res = -EINVAL;
+				break;
+			}
+
+			rdwr_pa[i].len = rdwr_pa[i].buf[0];
+		}
 	}
 	if (res < 0) {
 		int j;
diff --git a/drivers/input/joystick/as5011.c b/drivers/input/joystick/as5011.c
index 3063464474bf..57d19d4e0a2d 100644
--- a/drivers/input/joystick/as5011.c
+++ b/drivers/input/joystick/as5011.c
@@ -231,6 +231,7 @@ static int __devinit as5011_probe(struct i2c_client *client,
 	}
 
 	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_NOSTART |
 				     I2C_FUNC_PROTOCOL_MANGLING)) {
 		dev_err(&client->dev,
 			"need i2c bus that supports protocol mangling\n");
diff --git a/drivers/video/matrox/matroxfb_maven.c b/drivers/video/matrox/matroxfb_maven.c
index 31b8f67477b7..217678e0b983 100644
--- a/drivers/video/matrox/matroxfb_maven.c
+++ b/drivers/video/matrox/matroxfb_maven.c
@@ -1243,6 +1243,7 @@ static int maven_probe(struct i2c_client *client,
 
 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WRITE_WORD_DATA |
 					      I2C_FUNC_SMBUS_BYTE_DATA |
+					      I2C_FUNC_NOSTART |
 					      I2C_FUNC_PROTOCOL_MANGLING))
 		goto ERROR0;
 	if (!(data = kzalloc(sizeof(*data), GFP_KERNEL))) {
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index b66cb601435f..ddfa04108baf 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -541,7 +541,7 @@ struct i2c_msg {
 	__u16 flags;
 #define I2C_M_TEN		0x0010	/* this is a ten bit chip address */
 #define I2C_M_RD		0x0001	/* read data, from slave to master */
-#define I2C_M_NOSTART		0x4000	/* if I2C_FUNC_PROTOCOL_MANGLING */
+#define I2C_M_NOSTART		0x4000	/* if I2C_FUNC_NOSTART */
 #define I2C_M_REV_DIR_ADDR	0x2000	/* if I2C_FUNC_PROTOCOL_MANGLING */
 #define I2C_M_IGNORE_NAK	0x1000	/* if I2C_FUNC_PROTOCOL_MANGLING */
 #define I2C_M_NO_RD_ACK		0x0800	/* if I2C_FUNC_PROTOCOL_MANGLING */
@@ -554,8 +554,9 @@ struct i2c_msg {
 
 #define I2C_FUNC_I2C			0x00000001
 #define I2C_FUNC_10BIT_ADDR		0x00000002
-#define I2C_FUNC_PROTOCOL_MANGLING	0x00000004 /* I2C_M_NOSTART etc. */
+#define I2C_FUNC_PROTOCOL_MANGLING	0x00000004 /* I2C_M_IGNORE_NAK etc. */
 #define I2C_FUNC_SMBUS_PEC		0x00000008
+#define I2C_FUNC_NOSTART		0x00000010 /* I2C_M_NOSTART */
 #define I2C_FUNC_SMBUS_BLOCK_PROC_CALL	0x00008000 /* SMBus 2.0 */
 #define I2C_FUNC_SMBUS_QUICK		0x00010000
 #define I2C_FUNC_SMBUS_READ_BYTE	0x00020000