* David Brownell <[email protected]> [080924 22:51]:
> Hardware IRQ debouncing is common for IRQ controllers which are
> part of GPIO modules ... they often deal with mechanical switches,
> buttons, and so forth. This patch:
>
> - Provides simple support for that in genirq
>
> - Includes sample implementations for some Linux systems
> which already include non-generic support for this:
>
> * Atmel SOCs (AT91, AT32 -- the same GPIO module)
> * OMAP2/OMAP3 (not quite as simple)
>
> Control over how long to debounce is less common, and often applies
> to banks of GPIOs not individual signals ... not addressed here.
>
> Drivers can request this (where available) with a new IRQF_DEBOUNCED
> flag/hint passed to request_irq():
>
> IF that flag is set when a handler is registered
> AND the relevant irq_chip supports debouncing
> AND the IRQ isn't already flagged as being debounced
> THEN the irq_chip is asked to enable debouncing for this IRQ
> UNTIL the IRQ's last handler is unregistered.
> ELSE
> nothing is done ... the hint is ignored
> FI
>
> Comments?
>
> Having this mechanism in genirq would let boards remove a bunch of
> nonportable code, and would let drivers like gpio_keys, gpio_mouse,
> and various touchscreens work more reliably. It'd also let various
> SOC-specific MMC and CF card drivers switch over to more standard
> (and widely understandable) mechanisms.
Yeah this would nuke bunch of omap specific code for dealing with
battery covers, MMC slot open etc..
> I'd like to submit such updates for the 2.6.28 merge window, in
> part to let mainline avoid needing yet another driver-specific
> programming interface for IRQ debouncing. (For TWL4030/TPS659x0,
> as used in most OMAP3 boards including the Gumstix Overo and the
> BeagleBoard.)
What's the plan for sysfs_notify event for these switches? Are you
planning to add something like that to gpiolib?
Tony
> p.s. Tony and Kevin: note the locking bugfix in the OMAP2/3 bit.
Here's my ack for that:
Acked-by: Tony Lindgren <[email protected]>
>
> ---
> arch/arm/mach-at91/gpio.c | 13 +++++++++++++
> arch/arm/plat-omap/gpio.c | 15 ++++++++++++++-
> arch/avr32/mach-at32ap/pio.c | 14 ++++++++++++++
> include/linux/interrupt.h | 2 ++
> include/linux/irq.h | 3 +++
> kernel/irq/manage.c | 27 +++++++++++++++++++++++++++
> 6 files changed, 73 insertions(+), 1 deletion(-)
>
> --- a/arch/arm/mach-at91/gpio.c
> +++ b/arch/arm/mach-at91/gpio.c
> @@ -368,12 +368,25 @@ static int gpio_irq_type(unsigned pin, u
> }
> }
>
> +static int gpio_irq_debounce(unsigned pin, bool is_on)
> +{
> + void __iomem *pio = pin_to_controller(pin);
> + unsigned mask = pin_to_mask(pin);
> +
> + if (is_on)
> + __raw_writel(mask, pio + PIO_IFER);
> + else
> + __raw_writel(mask, pio + PIO_IFDR);
> + return 0;
> +}
> +
> static struct irq_chip gpio_irqchip = {
> .name = "GPIO",
> .mask = gpio_irq_mask,
> .unmask = gpio_irq_unmask,
> .set_type = gpio_irq_type,
> .set_wake = gpio_irq_set_wake,
> + .debounce = gpio_irq_debounce,
> };
>
> static void gpio_irq_handler(unsigned irq, struct irq_desc *desc)
> --- a/arch/arm/plat-omap/gpio.c
> +++ b/arch/arm/plat-omap/gpio.c
> @@ -472,6 +472,7 @@ void omap_set_gpio_debounce(int gpio, in
> {
> struct gpio_bank *bank;
> void __iomem *reg;
> + unsigned long flags;
> u32 val, l = 1 << get_gpio_index(gpio);
>
> if (cpu_class_is_omap1())
> @@ -479,8 +480,9 @@ void omap_set_gpio_debounce(int gpio, in
>
> bank = get_gpio_bank(gpio);
> reg = bank->base;
> -
> reg += OMAP24XX_GPIO_DEBOUNCE_EN;
> +
> + spin_lock_irqsave(&bank->lock, flags);
> val = __raw_readl(reg);
>
> if (enable)
> @@ -489,6 +491,7 @@ void omap_set_gpio_debounce(int gpio, in
> val &= ~l;
>
> __raw_writel(val, reg);
> + spin_unlock_irqrestore(&bank->lock, flags);
> }
> EXPORT_SYMBOL(omap_set_gpio_debounce);
>
> @@ -1109,6 +1112,12 @@ static void gpio_unmask_irq(unsigned int
> _set_gpio_irqenable(bank, gpio, 1);
> }
>
> +static int gpio_irq_debounce(unsigned int irq, bool is_on)
> +{
> + omap_set_gpio_debounce(irq - IH_GPIO_BASE, is_on);
> + return 0;
> +}
> +
> static struct irq_chip gpio_irq_chip = {
> .name = "GPIO",
> .shutdown = gpio_irq_shutdown,
> @@ -1437,6 +1446,10 @@ static int __init _omap_gpio_init(void)
> (rev >> 4) & 0x0f, rev & 0x0f);
> }
> #endif
> +
> + if (cpu_is_omap242x() || cpu_is_omap243x() || cpu_is_omap34xx())
> + gpio_irq_chip.debounce = gpio_irq_debounce;
> +
> for (i = 0; i < gpio_bank_count; i++) {
> int j, gpio_count = 16;
>
> --- a/arch/avr32/mach-at32ap/pio.c
> +++ b/arch/avr32/mach-at32ap/pio.c
> @@ -234,11 +234,25 @@ static int gpio_irq_type(unsigned irq, u
> return 0;
> }
>
> +static int gpio_irq_debounce(unsigned irq, bool is_on)
> +{
> + unsigned gpio = irq_to_gpio(irq);
> + struct pio_device *pio = &pio_dev[gpio >> 5];
> + u32 mask = 1 << (gpio & 0x1f);
> +
> + if (is_on)
> + pio_writel(pio, IFER, mask);
> + else
> + pio_writel(pio, IFDR, mask);
> + return 0;
> +}
> +
> static struct irq_chip gpio_irqchip = {
> .name = "gpio",
> .mask = gpio_irq_mask,
> .unmask = gpio_irq_unmask,
> .set_type = gpio_irq_type,
> + .debounce = gpio_irq_debounce,
> };
>
> static void gpio_irq_handler(unsigned irq, struct irq_desc *desc)
> --- a/include/linux/interrupt.h
> +++ b/include/linux/interrupt.h
> @@ -45,6 +45,7 @@
> * IRQF_IRQPOLL - Interrupt is used for polling (only the interrupt that is
> * registered first in an shared interrupt is considered for
> * performance reasons)
> + * IRQF_DEBOUNCED - Interrupt should use hardware debouncing where possible
> */
> #define IRQF_DISABLED 0x00000020
> #define IRQF_SAMPLE_RANDOM 0x00000040
> @@ -54,6 +55,7 @@
> #define IRQF_PERCPU 0x00000400
> #define IRQF_NOBALANCING 0x00000800
> #define IRQF_IRQPOLL 0x00001000
> +#define IRQF_DEBOUNCED 0x00002000
>
> typedef irqreturn_t (*irq_handler_t)(int, void *);
>
> --- a/include/linux/irq.h
> +++ b/include/linux/irq.h
> @@ -44,6 +44,7 @@ typedef void (*irq_flow_handler_t)(unsig
> #define IRQ_TYPE_LEVEL_LOW 0x00000008 /* Level low type */
> #define IRQ_TYPE_SENSE_MASK 0x0000000f /* Mask of the above */
> #define IRQ_TYPE_PROBE 0x00000010 /* Probing in progress */
> +#define IRQ_TYPE_DEBOUNCED 0x00000020 /* Hardware debouncing enabled */
>
> /* Internal flags */
> #define IRQ_INPROGRESS 0x00000100 /* IRQ handler active - do not enter! */
> @@ -92,6 +93,7 @@ struct msi_desc;
> * @retrigger: resend an IRQ to the CPU
> * @set_type: set the flow type (IRQ_TYPE_LEVEL/etc.) of an IRQ
> * @set_wake: enable/disable power-management wake-on of an IRQ
> + * @debounce: enable/disable hardware debouncing of an IRQ
> *
> * @release: release function solely used by UML
> * @typename: obsoleted by name, kept as migration helper
> @@ -114,6 +116,7 @@ struct irq_chip {
> int (*retrigger)(unsigned int irq);
> int (*set_type)(unsigned int irq, unsigned int flow_type);
> int (*set_wake)(unsigned int irq, unsigned int on);
> + int (*debounce)(unsigned int irq, bool is_on);
>
> /* Currently used only by UML, might disappear one day.*/
> #ifdef CONFIG_IRQ_RELEASE_METHOD
> --- a/kernel/irq/manage.c
> +++ b/kernel/irq/manage.c
> @@ -445,6 +445,18 @@ int setup_irq(unsigned int irq, struct i
> desc->irq_count = 0;
> desc->irqs_unhandled = 0;
>
> + /* Maybe enable hardware debouncing */
> + if ((new->flags & IRQF_DEBOUNCED)
> + && desc->chip->debounce
> + && !(desc->status & IRQ_TYPE_DEBOUNCED)) {
> + ret = desc->chip->debounce(irq, true);
> + if (ret < 0)
> + pr_debug("IRQ: can't debounce irq %d, err %d\n",
> + irq, ret);
> + else
> + desc->status |= IRQ_TYPE_DEBOUNCED;
> + }
> +
> /*
> * Check whether we disabled the irq via the spurious handler
> * before. Reenable it and give it another chance.
> @@ -524,6 +536,21 @@ void free_irq(unsigned int irq, void *de
>
> if (!desc->action) {
> desc->status |= IRQ_DISABLED;
> +
> + /* Maybe disable hardware debouncing */
> + if ((desc->status & IRQ_TYPE_DEBOUNCED)
> + && desc->chip->debounce) {
> + int status;
> +
> + status = desc->chip->debounce(irq, false);
> + if (status < 0)
> + pr_debug("IRQ: irq %d still "
> + "being debounced, err %d\n",
> + irq, status);
> + else
> + desc->status &= ~IRQ_TYPE_DEBOUNCED;
> + }
> +
> if (desc->chip->shutdown)
> desc->chip->shutdown(irq);
> else
On Friday 03 October 2008, Tony Lindgren wrote:
> * David Brownell <[email protected]> [080924 22:51]:
> > Hardware IRQ debouncing is common for IRQ controllers which are
> > part of GPIO modules ... they often deal with mechanical switches,
> > buttons, and so forth. This patch:
> >
> > - Provides simple support for that in genirq
> >
> > - Includes sample implementations for some Linux systems
> > which already include non-generic support for this:
> >
> > * Atmel SOCs (AT91, AT32 -- the same GPIO module)
> > * OMAP2/OMAP3 (not quite as simple)
> >
> > ...
> > Comments?
> >
> > Having this mechanism in genirq would let boards remove a bunch of
> > nonportable code, and would let drivers like gpio_keys, gpio_mouse,
> > and various touchscreens work more reliably. It'd also let various
> > SOC-specific MMC and CF card drivers switch over to more standard
> > (and widely understandable) mechanisms.
>
> Yeah this would nuke bunch of omap specific code for dealing with
> battery covers, MMC slot open etc..
It would be hidden away behind IRQF_DEBOUNCE ... not so much
making the code vanish, as making hardware-specific interfaces
vanish in favor of what seems to be the most popular idiom.
(Regular input GPIOs could be debounced too, but every time
I've noticed debouncing in use, it's coupled to an IRQ.)
> > I'd like to submit such updates for the 2.6.28 merge window, in
> > part to let mainline avoid needing yet another driver-specific
> > programming interface for IRQ debouncing. (For TWL4030/TPS659x0,
> > as used in most OMAP3 boards including the Gumstix Overo and the
> > BeagleBoard.)
>
> What's the plan for sysfs_notify event for these switches? Are you
> planning to add something like that to gpiolib?
I'm not sure what you mean -- which particular switches?
If the issue is the MMC card detect switches, that seems
more like an MMC question...
There was discussion of having the gpio_export() code
support notification that way, triggered by interrupts
on IRQ-capable GPIOs, but nobody seems to have wanted
it enough to translate from talk to code. ;)
- Dave
> Tony
>
>
> > p.s. Tony and Kevin: note the locking bugfix in the OMAP2/3 bit.
>
> Here's my ack for that:
>
> Acked-by: Tony Lindgren <[email protected]>
For the whole patch, I'll presume, not just that locking fix. ;)
>
> >
> > ---
> > arch/arm/mach-at91/gpio.c | 13 +++++++++++++
> > arch/arm/plat-omap/gpio.c | 15 ++++++++++++++-
> > arch/avr32/mach-at32ap/pio.c | 14 ++++++++++++++
> > include/linux/interrupt.h | 2 ++
> > include/linux/irq.h | 3 +++
> > kernel/irq/manage.c | 27 +++++++++++++++++++++++++++
> > 6 files changed, 73 insertions(+), 1 deletion(-)
> >
* David Brownell <[email protected]> [081003 11:45]:
> On Friday 03 October 2008, Tony Lindgren wrote:
> > * David Brownell <[email protected]> [080924 22:51]:
> > > Hardware IRQ debouncing is common for IRQ controllers which are
> > > part of GPIO modules ... they often deal with mechanical switches,
> > > buttons, and so forth. This patch:
> > >
> > > - Provides simple support for that in genirq
> > >
> > > - Includes sample implementations for some Linux systems
> > > which already include non-generic support for this:
> > >
> > > * Atmel SOCs (AT91, AT32 -- the same GPIO module)
> > > * OMAP2/OMAP3 (not quite as simple)
> > >
> > > ...
> > > Comments?
> > >
> > > Having this mechanism in genirq would let boards remove a bunch of
> > > nonportable code, and would let drivers like gpio_keys, gpio_mouse,
> > > and various touchscreens work more reliably. It'd also let various
> > > SOC-specific MMC and CF card drivers switch over to more standard
> > > (and widely understandable) mechanisms.
> >
> > Yeah this would nuke bunch of omap specific code for dealing with
> > battery covers, MMC slot open etc..
>
> It would be hidden away behind IRQF_DEBOUNCE ... not so much
> making the code vanish, as making hardware-specific interfaces
> vanish in favor of what seems to be the most popular idiom.
>
> (Regular input GPIOs could be debounced too, but every time
> I've noticed debouncing in use, it's coupled to an IRQ.)
>
> > > I'd like to submit such updates for the 2.6.28 merge window, in
> > > part to let mainline avoid needing yet another driver-specific
> > > programming interface for IRQ debouncing. (For TWL4030/TPS659x0,
> > > as used in most OMAP3 boards including the Gumstix Overo and the
> > > BeagleBoard.)
> >
> > What's the plan for sysfs_notify event for these switches? Are you
> > planning to add something like that to gpiolib?
>
> I'm not sure what you mean -- which particular switches?
> If the issue is the MMC card detect switches, that seems
> more like an MMC question...
>
> There was discussion of having the gpio_export() code
> support notification that way, triggered by interrupts
> on IRQ-capable GPIOs, but nobody seems to have wanted
> it enough to translate from talk to code. ;)
Well in linux-omap tree we have the gpio-switch.c that is handy for
generic state switched like headset connected etc. It shows the
events also via sysfs_notify() so userspace can pop up messages.
That code should use gpiolib.. But I was wondering if we'll need it
eventually at all.
Tony
>
> - Dave
>
>
> > Tony
> >
> >
> > > p.s. Tony and Kevin: note the locking bugfix in the OMAP2/3 bit.
> >
> > Here's my ack for that:
> >
> > Acked-by: Tony Lindgren <[email protected]>
>
> For the whole patch, I'll presume, not just that locking fix. ;)
Sure :)
>
> >
> > >
> > > ---
> > > arch/arm/mach-at91/gpio.c | 13 +++++++++++++
> > > arch/arm/plat-omap/gpio.c | 15 ++++++++++++++-
> > > arch/avr32/mach-at32ap/pio.c | 14 ++++++++++++++
> > > include/linux/interrupt.h | 2 ++
> > > include/linux/irq.h | 3 +++
> > > kernel/irq/manage.c | 27 +++++++++++++++++++++++++++
> > > 6 files changed, 73 insertions(+), 1 deletion(-)
> > >