From: David Rivshin <DRivshin@xxxxxxxxxxx>
omap_gpio_debounce() does not validate that the requested debounce
is within a range it can handle. Instead it lets the register value
wrap silently, and always returns success.
This can lead to all sorts of unexpected behavior, such as gpio_keys
asking for a too-long debounce, but getting a very short debounce in
practice.
Fix this by returning -EINVAL if the requested value does not fit into
the register field. If there is no debounce clock available at all,
return -ENOTSUPP.
Fixes: e85ec6c3047b ("gpio: omap: fix omap2_set_gpio_debounce")
Cc: <stable@xxxxxxxxxxxxxxx> # 4.3+
Signed-off-by: David Rivshin <drivshin@xxxxxxxxxxx>
---
Changes since v1 (https://lkml.org/lkml/2017/3/16/1094):
- Added dev_info() in omap_gpio_debounce() on error.
drivers/gpio/gpio-omap.c | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)
diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
index efc85a2..fd9bce9 100644
--- a/drivers/gpio/gpio-omap.c
+++ b/drivers/gpio/gpio-omap.c
@@ -208,9 +208,11 @@ static inline void omap_gpio_dbck_disable(struct gpio_bank *bank)
* OMAP's debounce time is in 31us steps
* <debounce time> = (GPIO_DEBOUNCINGTIME[7:0].DEBOUNCETIME + 1) x 31
* so we need to convert and round up to the closest unit.
+ *
+ * Return: 0 on success, negative error otherwise.
*/
-static void omap2_set_gpio_debounce(struct gpio_bank *bank, unsigned offset,
- unsigned debounce)
+static int omap2_set_gpio_debounce(struct gpio_bank *bank, unsigned offset,
+ unsigned debounce)
{
void __iomem *reg;
u32 val;
@@ -218,11 +220,12 @@ static void omap2_set_gpio_debounce(struct gpio_bank *bank, unsigned offset,
bool enable = !!debounce;
if (!bank->dbck_flag)
- return;
+ return -ENOTSUPP;
if (enable) {
debounce = DIV_ROUND_UP(debounce, 31) - 1;
- debounce &= OMAP4_GPIO_DEBOUNCINGTIME_MASK;
+ if ((debounce & OMAP4_GPIO_DEBOUNCINGTIME_MASK) != debounce)
+ return -EINVAL;
}
l = BIT(offset);
@@ -255,6 +258,8 @@ static void omap2_set_gpio_debounce(struct gpio_bank *bank, unsigned offset,
bank->context.debounce = debounce;
bank->context.debounce_en = val;
}
+
+ return 0;
}
/**
@@ -964,14 +969,20 @@ static int omap_gpio_debounce(struct gpio_chip *chip, unsigned offset,
{
struct gpio_bank *bank;
unsigned long flags;
+ int ret;
bank = gpiochip_get_data(chip);
raw_spin_lock_irqsave(&bank->lock, flags);
- omap2_set_gpio_debounce(bank, offset, debounce);
+ ret = omap2_set_gpio_debounce(bank, offset, debounce);
raw_spin_unlock_irqrestore(&bank->lock, flags);
- return 0;
+ if (ret)
+ dev_info(chip->parent,
+ "Could not set line %u debounce to %u microseconds (%d)",
+ offset, debounce, ret);
+
+ return ret;
}
static int omap_gpio_set_config(struct gpio_chip *chip, unsigned offset,
--
2.9.3
base-commit: 5a7ad1146caa895ad718a534399e38bd2ba721b7
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