i2c: Split I2C_M_NOSTART support out of I2C_FUNC_PROTOCOL_MANGLING

Since there are uses for I2C_M_NOSTART which are much more sensible and
standard than most of the protocol mangling functionality (the main one
being gather writes to devices where something like a register address
needs to be inserted before a block of data) create a new I2C_FUNC_NOSTART
for this feature and update all the users to use it.

Also strengthen the disrecommendation of the protocol mangling while we're
at it.

In the case of regmap-i2c we remove the requirement for mangling as
I2C_M_NOSTART is the only mangling feature which is being used.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

diff --git a/Documentation/i2c/functionality b/Documentation/i2c/functionality
index 42c17c1..b0ff2ab 100644 (file)
--- 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 10518dd..0b3e62d 100644 (file)
--- 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 5f6b247..fa6bf52 100644 (file)
--- 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 7f0b832..fad22b0 100644 (file)
--- 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 03b6157..a26dfb8 100644 (file)
--- 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 fa0b134..0195915 100644 (file)
--- 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/input/joystick/as5011.c b/drivers/input/joystick/as5011.c
index 3063464..57d19d4 100644 (file)
--- 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 31b8f67..217678e 100644 (file)
--- 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 b66cb60..ddfa041 100644 (file)
--- 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