gpiolib updates

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

Hi David,

If gpiolib isn't in git yet, then indeed updating the patch that creates it before it goes in git sounds more sensible. Let's not make the git history more complex than needed.

Thanks,

Jean Delvare