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Commit 14674e70 authored by Mark Brown's avatar Mark Brown Committed by Jean Delvare
Browse files

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: default avatarMark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: default avatarWolfram Sang <w.sang@pengutronix.de>
Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
parent 838bfa60

Documentation/i2c/functionality

+6 −3
Original line number Original line Diff line number Diff line
@@ -18,9 +18,9 @@ For the most up-to-date list of functionality constants, please check 
                                  adapters typically can not do these)

                                  adapters typically can not do these)

  I2C_FUNC_10BIT_ADDR             Handles the 10-bit address extensions

  I2C_FUNC_10BIT_ADDR             Handles the 10-bit address extensions

  I2C_FUNC_PROTOCOL_MANGLING      Knows about the I2C_M_IGNORE_NAK,

  I2C_FUNC_PROTOCOL_MANGLING      Knows about the I2C_M_IGNORE_NAK,

                                  I2C_M_REV_DIR_ADDR, I2C_M_NOSTART and

                                  I2C_M_REV_DIR_ADDR and I2C_M_NO_RD_ACK

                                  I2C_M_NO_RD_ACK flags (which modify the

                                  flags (which modify the I2C protocol!)

                                  I2C protocol!)

  I2C_FUNC_NOSTART                Can skip repeated start sequence

  I2C_FUNC_SMBUS_QUICK            Handles the SMBus write_quick command

  I2C_FUNC_SMBUS_QUICK            Handles the SMBus write_quick command

  I2C_FUNC_SMBUS_READ_BYTE        Handles the SMBus read_byte command

  I2C_FUNC_SMBUS_READ_BYTE        Handles the SMBus read_byte command

  I2C_FUNC_SMBUS_WRITE_BYTE       Handles the SMBus write_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

                                  emulated by a real I2C adapter (using

                                  the transparent emulation layer)

                                  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

ADAPTER IMPLEMENTATION

----------------------

----------------------

Documentation/i2c/i2c-protocol

+8 −1
Original line number Original line Diff line number Diff line
@@ -49,7 +49,9 @@ a byte read, followed by a byte write: 
Modified transactions

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: 

  Flag I2C_M_NOSTART: 

    In a combined transaction, no 'S Addr Wr/Rd [A]' is generated at some

    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

    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.

    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

  Flags I2C_M_REV_DIR_ADDR

    This toggles the Rd/Wr flag. That is, if you want to do a write, but

    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

    need to emit an Rd instead of a Wr, or vice versa, you set this

drivers/base/regmap/regmap-i2c.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -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

	/* If the I2C controller can't do a gather tell the core, it

	 * will substitute in a linear write for us.

	 * 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;

		return -ENOTSUPP;





	xfer[0].addr = i2c->addr;

	xfer[0].addr = i2c->addr;

drivers/i2c/algos/i2c-algo-bit.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -608,7 +608,7 @@ bailout: 




static u32 bit_func(struct i2c_adapter *adap)

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_READ_BLOCK_DATA |

	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL |

	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL |

	       I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;

	       I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;

drivers/i2c/busses/i2c-nuc900.c

+2 −1
Original line number Original line Diff line number Diff line
@@ -502,7 +502,8 @@ static int nuc900_i2c_xfer(struct i2c_adapter *adap, 
/* declare our i2c functionality */

/* declare our i2c functionality */

static u32 nuc900_i2c_func(struct i2c_adapter *adap)

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 */

/* i2c bus registration info */