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@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
---
Documentation/i2c/functionality | 8 +++++---
Documentation/i2c/i2c-protocol | 9 ++++++++-
drivers/base/regmap/regmap-i2c.c | 2 +-
drivers/i2c/algos/i2c-algo-bit.c | 2 +-
drivers/i2c/busses/i2c-nuc900.c | 3 ++-
drivers/i2c/busses/i2c-s3c2410.c | 3 ++-
drivers/input/joystick/as5011.c | 1 +
drivers/video/matrox/matroxfb_maven.c | 1 +
include/linux/i2c.h | 5 +++--
9 files changed, 24 insertions(+), 10 deletions(-)
diff --git a/Documentation/i2c/functionality b/Documentation/i2c/functionality
index 42c17c1..7cbd5da 100644
--- a/Documentation/i2c/functionality
+++ b/Documentation/i2c/functionality
@@ -18,9 +18,8 @@ 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_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
@@ -33,6 +32,7 @@ For the most up-to-date list of functionality constants, please check
I2C_FUNC_SMBUS_WRITE_BLOCK_DATA Handles the SMBus write_block_data command
I2C_FUNC_SMBUS_READ_I2C_BLOCK Handles the SMBus read_i2c_block_data command
I2C_FUNC_SMBUS_WRITE_I2C_BLOCK Handles the SMBus write_i2c_block_data command
+ I2C_FUNC_NOSTART Can skip repeated start sequence
A few combinations of the above flags are also defined for your convenience:
@@ -50,6 +50,8 @@ 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
--- 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 9a3a8c5..157bbd5 100644
--- a/drivers/base/regmap/regmap-i2c.c
+++ b/drivers/base/regmap/regmap-i2c.c
@@ -40,7 +40,7 @@ static int regmap_i2c_gather_write(struct device *dev,
/* 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
--- 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
--- 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 737f721..37b1f90 100644
--- a/drivers/i2c/busses/i2c-s3c2410.c
+++ b/drivers/i2c/busses/i2c-s3c2410.c
@@ -591,7 +591,8 @@ 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
--- 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
--- 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 195d8b3..85d4ef1 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -540,7 +540,7 @@ 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 */
@@ -553,8 +553,9 @@ 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
--
1.7.10
--
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