From mboxrd@z Thu Jan 1 00:00:00 1970 From: shawn.guo@linaro.org (Shawn Guo) Date: Tue, 22 Jul 2014 14:28:05 +0800 Subject: [[RFC PATCH]] gpio: gpio-mxc: make sure gpio is input when request IRQ In-Reply-To: <1405518664-31313-1-git-send-email-list-09_linux_arm@tqsc.de> References: <1405518664-31313-1-git-send-email-list-09_linux_arm@tqsc.de> Message-ID: <20140722062803.GA21229@dragon> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Jul 16, 2014 at 03:51:04PM +0200, Markus Niebel wrote: > From: Markus Niebel > > 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 > --- > 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 >