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gpio: omap: return error if requested debounce time is not possible

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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@vger.kernel.org> # 4.3+
Signed-off-by: David Rivshin <drivshin@allworx.com>
Acked-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
David Rivshin 2017-04-24 18:56:50 -04:00 committed by Linus Walleij
parent 9384793036
commit 8397744393
1 changed files with 17 additions and 6 deletions
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23
drivers/gpio/gpio-omap.c
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@ -208,9 +208,11 @@ static inline void omap_gpio_dbck_disable(struct gpio_bank *bank)
* OMAP's debounce time is in 31us steps * OMAP's debounce time is in 31us steps
* <debounce time> = (GPIO_DEBOUNCINGTIME[7:0].DEBOUNCETIME + 1) x 31 * <debounce time> = (GPIO_DEBOUNCINGTIME[7:0].DEBOUNCETIME + 1) x 31
* so we need to convert and round up to the closest unit. * 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, static int omap2_set_gpio_debounce(struct gpio_bank *bank, unsigned offset,
unsigned debounce) unsigned debounce)
{ {
void __iomem *reg; void __iomem *reg;
u32 val; u32 val;
@ -218,11 +220,12 @@ static void omap2_set_gpio_debounce(struct gpio_bank *bank, unsigned offset,
bool enable = !!debounce; bool enable = !!debounce;
if (!bank->dbck_flag) if (!bank->dbck_flag)
return; return -ENOTSUPP;
if (enable) { if (enable) {
debounce = DIV_ROUND_UP(debounce, 31) - 1; debounce = DIV_ROUND_UP(debounce, 31) - 1;
debounce &= OMAP4_GPIO_DEBOUNCINGTIME_MASK; if ((debounce & OMAP4_GPIO_DEBOUNCINGTIME_MASK) != debounce)
return -EINVAL;
} }
l = BIT(offset); 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 = debounce;
bank->context.debounce_en = val; 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; struct gpio_bank *bank;
unsigned long flags; unsigned long flags;
int ret;
bank = gpiochip_get_data(chip); bank = gpiochip_get_data(chip);
raw_spin_lock_irqsave(&bank->lock, flags); 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); 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, static int omap_gpio_set_config(struct gpio_chip *chip, unsigned offset,