[patch 2.6.24-rc4-mm 0/6] gpiolib updates

From: David Brownell
Date: Sun Dec 09 2007 - 23:52:18 EST


Following this are several patches updating the current gpio
implemenentation framework. Because one of those changes
involves creating a new drivers/gpio directory, the patches
are a bit simpler if two existing patches are first removed
from the MM tree:

mcp23s08-spi-gpio-expander.patch
mcp23s08-spi-gpio-expander-checkpatch-fixes.patch

The patches in this series are:

- Adding a gpio_desc[] layer, making it easier to mix in
gpio_chips with different numbers of GPIOs without any
large holes in the number sequence. When those holes
are also reflected in IRQ number sequences, they cost
a lot of memory. (Based on work from Eric Miao.)

- More diagnostics with CONFIG_DEBUG_GPIO. Handy when
bringing up a new board, needless later. (Various
platforms had similar diagnostics.)

- A bit of implementor-oriented documentation for this
gpiolib infrastructure.

- Create a new drivers/gpio directory for expanders and
(eventually) other code. (Strongly encouraged by
Jean Delvare, to help shrink drivers/i2c/chips.)

- New-style I2C driver for pcf8574/pcf8575/compatible
GPIO expanders ... these are pretty widely used.
(This was previously posted as patch/rfc.)

- Relocated mcp23s08 driver. This includes two minor
functional changes, to handle the gpio_desc changes
and modified driver init sequence, and it merges the
minor checkpatch.pl update above.

There's an updated pca9539 driver in the works too; it
should land in the drivers/i2c directory.

I'm thinking there should be a non-functional change to
the gpiolib code: move it from lib to drivers/gpio.

My question is whether that's better done by replacing
the current patches with one new patch, or by a patch
deleting the current lib/gpiolib.c and adding a new
drivers/gpio/gpiolib.c ... I think the former would
make more sense to anyone looking at GIT history.

- Dave
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