Re: [U-Boot] [PATCH] soft_i2c.c add option for repeated start in i2c_read()

2009-01-27 Thread Wolfgang Denk 
Dear Andrew Dyer,

In message 49595ee1.8040...@righthandtech.com you wrote:
 
 This patch adds a #define to optionally change the behaviour of
 i2c_read() in soft_i2c.c to send an I2C repeated start instead of a
 stop-start between sending the device address pointer write and
 reading back the data.  The current behaviour is retained as the
 default.
 
 While most devices will work either way, I have a smart battery(*) that
 requires repeated start, and someone at some point found a device that
 required a stop-start.
 
 (*) 
 http://www.inspired-energy.com/Standard_Products/NL2054/NL2054%20Rev1.0%20Data%20Sheet.pdf
 
 Signed-off-by: Andrew Dyer ad...@righthandtech.com
 ---
  README |9 +
  drivers/i2c/soft_i2c.c |   12 +++-
  2 files changed, 20 insertions(+), 1 deletions(-)

Applied, thanks.

Best regards,

Wolfgang Denk

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HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
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[U-Boot] [PATCH] soft_i2c.c add option for repeated start in i2c_read()

2008-12-29 Thread Andrew Dyer 

This patch adds a #define to optionally change the behaviour of
i2c_read() in soft_i2c.c to send an I2C repeated start instead of a
stop-start between sending the device address pointer write and
reading back the data.  The current behaviour is retained as the
default.

While most devices will work either way, I have a smart battery(*) that
requires repeated start, and someone at some point found a device that
required a stop-start.

(*) 
http://www.inspired-energy.com/Standard_Products/NL2054/NL2054%20Rev1.0%20Data%20Sheet.pdf

Signed-off-by: Andrew Dyer ad...@righthandtech.com
---
 README |9 +
 drivers/i2c/soft_i2c.c |   12 +++-
 2 files changed, 20 insertions(+), 1 deletions(-)

diff --git a/README b/README
index 2a553c2..763fb7a 100644
--- a/README
+++ b/README
@@ -1496,6 +1496,15 @@ The following options need to be configured:
Bus on the MPC8260. But it should be not so difficult
to add this option to other architectures.
 
+   CONFIG_SOFT_I2C_READ_REPEATED_START
+
+   defining this will force the i2c_read() function in
+   the soft_i2c driver to perform an I2C repeated start
+   between writing the address pointer and reading the
+   data.  If this define is omitted the default behaviour
+   of doing a stop-start sequence will be used.  Most I2C
+   devices can use either method, but some require one or
+   the other.
 
 - SPI Support: CONFIG_SPI
 
diff --git a/drivers/i2c/soft_i2c.c b/drivers/i2c/soft_i2c.c
index a27de5a..da6cec1 100644
--- a/drivers/i2c/soft_i2c.c
+++ b/drivers/i2c/soft_i2c.c
@@ -385,8 +385,18 @@ int  i2c_read(uchar chip, uint addr, int alen, uchar 
*buffer, int len)
}
shift -= 8;
}
-   send_stop();/* reportedly some chips need a full stop */
+
+   /* Some I2C chips need a stop/start sequence here,
+* other chips don't work with a full stop and need
+* only a start.  Default behaviour is to send the
+* stop/start sequence.
+*/
+#ifdef CONFIG_SOFT_I2C_READ_REPEATED_START
send_start();
+#else
+   send_stop();
+   send_start();
+#endif
}
/*
 * Send the chip address again, this time for a read cycle.
-- 
1.5.6.3

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