From mboxrd@z Thu Jan 1 00:00:00 1970 From: list-09_linux_arm@tqsc.de (Markus Niebel) Date: Tue, 22 Jul 2014 09:19:22 +0200 Subject: [[RFC PATCH]] gpio: gpio-mxc: make sure gpio is input when request IRQ In-Reply-To: <20140722062803.GA21229@dragon> References: <1405518664-31313-1-git-send-email-list-09_linux_arm@tqsc.de> <20140722062803.GA21229@dragon> Message-ID: <53CE107A.1000000@tqsc.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Am 22.07.2014 08:28, wrote Shawn Guo: > 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. Thats why it is an RFC. I add Linus Walleij to the cc-list. Let me describe the problem: Currently client drivers have simply interrupts and interrupt-parent in their bindings, but no interrupt-gpios. Therefore in this case a client does not know about a dedicated gpio which is to be requested and configured. > >> + } 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. > Yes, but the current situation is even worse (in my eyes): an IRQ can be requested and an independend party can request and configure the gpio as output ... >> + } >> + >> + 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. Going that way as a consequence a reworked device tree binding for gpio irq is needed (just like in the platform data days) when providing a gpio number and the client has to request gpio and irq - correct me if I'm wrong. Maybe here is something needed with deeper knowledge in the gpio subsystem. > >> + >> + 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 >> > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel at lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >