Messages in this thread | | | From | Grant Likely <> | Subject | Re: [RFC] gpiolib: introduce descriptor-based GPIO interface | Date | Thu, 06 Dec 2012 14:42:59 +0000 |
| |
On Thu, 6 Dec 2012 16:45:18 +0900, Alexandre Courbot <acourbot@nvidia.com> wrote: > With the current API, GPIOs are manipulated through an integer which > represents their unique number across the system. This poses problems in > terms of portability, scalability and flexibility: for instance, the > number of valid GPIOs for a given system is fixed at system time, and a > large array of that size is statically allocated to hold the GPIO > descriptors. Worse, GPIOs can be used without being properly allocated. > > In order to improve the situation, the integer namespace must first get > away. This patch introduces an alternative GPIO API that uses opaque > handlers and refactor gpiolib's internals to work with these handlers > instead of GPIO numbers. The former integer-based API is still available > as a light wrapper around this new API. > > This first step will then us to build more improvements for gpiolib, > like proper GPIO lookup functions per device and provider, and getting > rid of the static GPIO array and the ARCH_NR_GPIO configuration option. > > Signed-off-by: Alexandre Courbot <acourbot@nvidia.com> > --- > drivers/gpio/gpiolib.c | 302 ++++++++++++++++++++++-------------------- > include/asm-generic/gpio.h | 74 ++++++++--- > include/linux/gpio/consumer.h | 45 +++++++ > 3 files changed, 261 insertions(+), 160 deletions(-) > create mode 100644 include/linux/gpio/consumer.h > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > index 1c8d9e3..bf32511 100644 > --- a/drivers/gpio/gpiolib.c > +++ b/drivers/gpio/gpiolib.c > @@ -83,6 +83,32 @@ static inline void desc_set_label(struct gpio_desc *d, const char *label) > #endif > } > > +/** > + * Convert a GPIO descriptor to the integer namespace. > + * This should disappear in the future but is needed since we still > + * use GPIO numbers for error messages and sysfs nodes > + */ > +static inline int desc_to_gpio(struct gpio_desc *desc) > +{ > + return desc - &gpio_desc[0]; > +} > + > +/** > + * Return the GPIO number of the passed descriptor relative to its chip > + */ > +int gpio_chip_offset(struct gpio_desc *desc) > +{ > + return (desc - &gpio_desc[0]) - desc->chip->base; > +}
how about "gpio_chip_hwnum()" to somewhat match irqdomain convention?
I've only lightly scanned this patch, but I like what I see. I would keep going with it.
g.
| |