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Subject[PATCH 1/1] pinctrl: exynos: Lock GPIOs as interrupts when used as EINTs
Date
From: Tomasz Figa <t.figa@samsung.com>

Currently after configuring a GPIO pin as an interrupt related pinmux
registers are changed, but there is no protection from calling
gpio_direction_*() in a badly written driver, which would cause the same
pinmux register to be reconfigured for regular input/output and this
disabling interrupt capability of the pin.

This patch addresses this issue by moving pinmux reconfiguration to
.irq_{request,release}_resources() callback of irq_chip and calling
gpio_lock_as_irq() helper to prevent reconfiguration of pin direction.

Setting up a GPIO interrupt on Samsung SoCs is a two-step operation -
in addition to trigger configuration in a dedicated register, the pinmux
must be also reconfigured to GPIO interrupt, which is a different function
than normal GPIO input, although I/O-wise they both behave in the same way
and gpio_get_value() can be used on a pin configured as IRQ as well.

Such design implies subtleties such as gpio_direction_input() not having
to fail if a pin is already configured as an interrupt nor change the
configuration to normal input. But the FLAG_USED_AS_IRQ set in gpiolib by
gpio_lock_as_irq() is only used to check that gpio_direction_output() is
not called, it's not used to prevent gpio_direction_input() to be called.
So this is not a complete solution for Samsung SoCs but it's definitely a
move in the right direction.

Signed-off-by: Tomasz Figa <t.figa@samsung.com>
[javier: use request resources instead of startup and expand commit message]
Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
---

This patch solves the issue explained in https://lkml.org/lkml/2014/8/8/461

drivers/pinctrl/samsung/pinctrl-exynos.c | 69 ++++++++++++++++++++++++++++---
drivers/pinctrl/samsung/pinctrl-samsung.h | 1 +
2 files changed, 64 insertions(+), 6 deletions(-)

diff --git a/drivers/pinctrl/samsung/pinctrl-exynos.c b/drivers/pinctrl/samsung/pinctrl-exynos.c
index 003bfd8..d7154ed 100644
--- a/drivers/pinctrl/samsung/pinctrl-exynos.c
+++ b/drivers/pinctrl/samsung/pinctrl-exynos.c
@@ -127,14 +127,10 @@ static int exynos_irq_set_type(struct irq_data *irqd, unsigned int type)
struct irq_chip *chip = irq_data_get_irq_chip(irqd);
struct exynos_irq_chip *our_chip = to_exynos_irq_chip(chip);
struct samsung_pin_bank *bank = irq_data_get_irq_chip_data(irqd);
- struct samsung_pin_bank_type *bank_type = bank->type;
struct samsung_pinctrl_drv_data *d = bank->drvdata;
- unsigned int pin = irqd->hwirq;
- unsigned int shift = EXYNOS_EINT_CON_LEN * pin;
+ unsigned int shift = EXYNOS_EINT_CON_LEN * irqd->hwirq;
unsigned int con, trig_type;
unsigned long reg_con = our_chip->eint_con + bank->eint_offset;
- unsigned long flags;
- unsigned int mask;

switch (type) {
case IRQ_TYPE_EDGE_RISING:
@@ -167,8 +163,32 @@ static int exynos_irq_set_type(struct irq_data *irqd, unsigned int type)
con |= trig_type << shift;
writel(con, d->virt_base + reg_con);

+ return 0;
+}
+
+static int exynos_irq_request_resources(struct irq_data *irqd)
+{
+ struct irq_chip *chip = irq_data_get_irq_chip(irqd);
+ struct exynos_irq_chip *our_chip = to_exynos_irq_chip(chip);
+ struct samsung_pin_bank *bank = irq_data_get_irq_chip_data(irqd);
+ struct samsung_pin_bank_type *bank_type = bank->type;
+ struct samsung_pinctrl_drv_data *d = bank->drvdata;
+ unsigned int shift = EXYNOS_EINT_CON_LEN * irqd->hwirq;
+ unsigned long reg_con = our_chip->eint_con + bank->eint_offset;
+ unsigned long flags;
+ unsigned int mask;
+ unsigned int con;
+ int ret;
+
+ ret = gpio_lock_as_irq(&bank->gpio_chip, irqd->hwirq);
+ if (ret) {
+ dev_err(bank->gpio_chip.dev, "unable to lock pin %s-%lu IRQ\n",
+ bank->name, irqd->hwirq);
+ return ret;
+ }
+
reg_con = bank->pctl_offset + bank_type->reg_offset[PINCFG_TYPE_FUNC];
- shift = pin * bank_type->fld_width[PINCFG_TYPE_FUNC];
+ shift = irqd->hwirq * bank_type->fld_width[PINCFG_TYPE_FUNC];
mask = (1 << bank_type->fld_width[PINCFG_TYPE_FUNC]) - 1;

spin_lock_irqsave(&bank->slock, flags);
@@ -180,9 +200,42 @@ static int exynos_irq_set_type(struct irq_data *irqd, unsigned int type)

spin_unlock_irqrestore(&bank->slock, flags);

+ exynos_irq_unmask(irqd);
+
return 0;
}

+static void exynos_irq_release_resources(struct irq_data *irqd)
+{
+ struct irq_chip *chip = irq_data_get_irq_chip(irqd);
+ struct exynos_irq_chip *our_chip = to_exynos_irq_chip(chip);
+ struct samsung_pin_bank *bank = irq_data_get_irq_chip_data(irqd);
+ struct samsung_pin_bank_type *bank_type = bank->type;
+ struct samsung_pinctrl_drv_data *d = bank->drvdata;
+ unsigned int shift = EXYNOS_EINT_CON_LEN * irqd->hwirq;
+ unsigned long reg_con = our_chip->eint_con + bank->eint_offset;
+ unsigned long flags;
+ unsigned int mask;
+ unsigned int con;
+
+ reg_con = bank->pctl_offset + bank_type->reg_offset[PINCFG_TYPE_FUNC];
+ shift = irqd->hwirq * bank_type->fld_width[PINCFG_TYPE_FUNC];
+ mask = (1 << bank_type->fld_width[PINCFG_TYPE_FUNC]) - 1;
+
+ exynos_irq_mask(irqd);
+
+ spin_lock_irqsave(&bank->slock, flags);
+
+ con = readl(d->virt_base + reg_con);
+ con &= ~(mask << shift);
+ con |= FUNC_INPUT << shift;
+ writel(con, d->virt_base + reg_con);
+
+ spin_unlock_irqrestore(&bank->slock, flags);
+
+ gpio_unlock_as_irq(&bank->gpio_chip, irqd->hwirq);
+}
+
/*
* irq_chip for gpio interrupts.
*/
@@ -193,6 +246,8 @@ static struct exynos_irq_chip exynos_gpio_irq_chip = {
.irq_mask = exynos_irq_mask,
.irq_ack = exynos_irq_ack,
.irq_set_type = exynos_irq_set_type,
+ .irq_request_resources = exynos_irq_request_resources,
+ .irq_release_resources = exynos_irq_release_resources,
},
.eint_con = EXYNOS_GPIO_ECON_OFFSET,
.eint_mask = EXYNOS_GPIO_EMASK_OFFSET,
@@ -336,6 +391,8 @@ static struct exynos_irq_chip exynos_wkup_irq_chip = {
.irq_ack = exynos_irq_ack,
.irq_set_type = exynos_irq_set_type,
.irq_set_wake = exynos_wkup_irq_set_wake,
+ .irq_request_resources = exynos_irq_request_resources,
+ .irq_release_resources = exynos_irq_release_resources,
},
.eint_con = EXYNOS_WKUP_ECON_OFFSET,
.eint_mask = EXYNOS_WKUP_EMASK_OFFSET,
diff --git a/drivers/pinctrl/samsung/pinctrl-samsung.h b/drivers/pinctrl/samsung/pinctrl-samsung.h
index 2b88232..5cedc9d 100644
--- a/drivers/pinctrl/samsung/pinctrl-samsung.h
+++ b/drivers/pinctrl/samsung/pinctrl-samsung.h
@@ -26,6 +26,7 @@
#include <linux/gpio.h>

/* pinmux function number for pin as gpio output line */
+#define FUNC_INPUT 0x0
#define FUNC_OUTPUT 0x1

/**
--
2.0.0.rc2


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