From: shawn.guo@linaro.org (Shawn Guo)
To: linux-arm-kernel@lists.infradead.org
Subject: [[RFC PATCH]] gpio: gpio-mxc: make sure gpio is input when request IRQ
Date: Tue, 22 Jul 2014 14:28:05 +0800 [thread overview]
Message-ID: <20140722062803.GA21229@dragon> (raw)
In-Reply-To: <1405518664-31313-1-git-send-email-list-09_linux_arm@tqsc.de>
On Wed, Jul 16, 2014 at 03:51:04PM +0200, Markus Niebel wrote:
> From: Markus Niebel <Markus.Niebel@tq-group.com>
>
> When requesting an GPIO irq for imx Soc two things are missing:
> - there is no check, if the GPIO is already requested
> - there is no check, if the GPIO is configured as input
>
> The first case can lead to reconfiguring the GPIO pin from third
> party while it is used as IRQ pin, second case will (eventually)
> prevent IRQ from being seen by SOC becaus the pin is driven by
> Soc
>
> This patch tries to implement (logic taken roughly from gpio-omap)
> - basic check if gpio already requested
> - if needed requests the gpio and configures as IN.
> - if gpio is already requested it is only verified if pin is IN
> - gpio is locked as irq
>
> Tested on a not mainlined i.MX6 based hardware with pin configured
> by bootloader as OUT HIGH and expecting a low active IRQ.
>
> Signed-off-by: Markus Niebel <Markus.Niebel@tq-group.com>
> ---
> drivers/gpio/gpio-mxc.c | 35 +++++++++++++++++++++++++++++++++++
> 1 file changed, 35 insertions(+)
>
> diff --git a/drivers/gpio/gpio-mxc.c b/drivers/gpio/gpio-mxc.c
> index db83b3c..4316a38 100644
> --- a/drivers/gpio/gpio-mxc.c
> +++ b/drivers/gpio/gpio-mxc.c
> @@ -175,6 +175,31 @@ static int gpio_set_irq_type(struct irq_data *d, u32 type)
> u32 gpio = port->bgc.gc.base + gpio_idx;
> int edge;
> void __iomem *reg = port->base;
> + int ret = 0;
> +
> + if (!gpiochip_is_requested(&port->bgc.gc, gpio_idx)) {
> + char label[32];
> +
> + snprintf(label, 32, "gpio%u-irq", gpio);
> + ret = gpio_request_one(gpio, GPIOF_DIR_IN, label);
I'm not sure it's correct to call gpio_request_one() from .set_irq_type
hook. It looks like a API usage violation to me. It should really be
called from client driver.
> + } else {
> + val = readl(port->base + GPIO_GDIR);
> + if (val & BIT(gpio_idx))
> + ret = -EINVAL;
It says that the GPIO is requested by someone, but we're not really sure
if it's the correct one, i.e. the one is requesting set_irq_type.
> + }
> +
> + if (ret) {
> + dev_err(port->bgc.gc.dev, "unable to set gpio_idx %u as IN\n",
> + gpio_idx);
> + return ret;
> + }
Having said that, I'm not sure any above changes is really necessary.
If any, I would say only gpiochip_is_requested() check makes some sense,
but we should just fail out if the GPIO hasn't been requested. Nothing
more can be done in there.
> +
> + ret = gpio_lock_as_irq(&port->bgc.gc, gpio_idx);
> + if (ret) {
> + dev_err(port->bgc.gc.dev, "unable to lock gpio_idx %u for IRQ\n",
> + gpio_idx);
> + return ret;
> + }
This and the following changes do make sense to me.
Shawn
>
> port->both_edges &= ~(1 << gpio_idx);
> switch (type) {
> @@ -231,6 +256,15 @@ static int gpio_set_irq_type(struct irq_data *d, u32 type)
> return 0;
> }
>
> +static void gpio_irq_shutdown(struct irq_data *d)
> +{
> + struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
> + struct mxc_gpio_port *port = gc->private;
> + u32 gpio_idx = d->hwirq;
> +
> + gpio_unlock_as_irq(&port->bgc.gc, gpio_idx);
> +}
> +
> static void mxc_flip_edge(struct mxc_gpio_port *port, u32 gpio)
> {
> void __iomem *reg = port->base;
> @@ -353,6 +387,7 @@ static void __init mxc_gpio_init_gc(struct mxc_gpio_port *port, int irq_base)
> ct->chip.irq_mask = irq_gc_mask_clr_bit;
> ct->chip.irq_unmask = irq_gc_mask_set_bit;
> ct->chip.irq_set_type = gpio_set_irq_type;
> + ct->chip.irq_shutdown = gpio_irq_shutdown;
> ct->chip.irq_set_wake = gpio_set_wake_irq;
> ct->regs.ack = GPIO_ISR;
> ct->regs.mask = GPIO_IMR;
> --
> 1.7.9.5
>
next prev parent reply other threads:[~2014-07-22 6:28 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-16 13:51 [[RFC PATCH]] gpio: gpio-mxc: make sure gpio is input when request IRQ Markus Niebel
2014-07-22 6:28 ` Shawn Guo [this message]
2014-07-22 7:19 ` Markus Niebel
2014-07-22 7:42 ` Shawn Guo
2014-07-23 16:14 ` Linus Walleij
2014-07-24 8:12 ` Markus Niebel
2014-07-25 11:38 ` Linus Walleij
2014-07-25 12:52 ` Markus Niebel
2014-07-25 13:52 ` Linus Walleij
2014-07-23 16:10 ` Linus Walleij
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