pca953x: support 16-pin devices
This adds support for for the PCA9535/PCA9539 family of gpio devices which
have 16 output pins.
To let the driver know which devices are 16-pin it is necessary to define
CONFIG_SYS_I2C_PCA953X_WIDTH in your board config file. This is used to
create an array of {chip, ngpio} tuples that are used to determine the
width of a particular chip. For backwards compatibility it is assumed that
any chip not defined in CONFIG_SYS_I2C_PCA953X_WIDTH has 8 pins.
Acked-by: Peter Tyser <ptyser@xes-inc.com>
Tested-by: Peter Tyser <ptyser@xes-inc.com>
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
diff --git a/README b/README
index 68f5fb0..831c5af 100644
--- a/README
+++ b/README
@@ -746,6 +746,10 @@
CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
CONFIG_PCA953X_INFO - enable pca953x info command
+ The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
+ chip-ngpio pairs that tell the PCA953X driver the number of
+ pins supported by a particular chip.
+
Note that if the GPIO device uses I2C, then the I2C interface
must also be configured. See I2C Support, below.