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authorGrygorii Strashko <grygorii.strashko@ti.com>2015-08-18 14:10:54 +0300
committerLinus Walleij <linus.walleij@linaro.org>2015-08-26 09:52:48 +0200
commite85ec6c3047be0646e7c572e24869c212b685c7c (patch)
treef74fd0cd279dd53693dc6e77010bb40109037a64 /drivers/gpio
parent89d18e3af8b99481589e07f92fd966ceb86eff5d (diff)
gpio: omap: fix omap2_set_gpio_debounce
According to TRMs: Required input line stable = (the value of the GPIO_DEBOUNCINGTIME[7:0].DEBOUNCETIME + 1) × 31, where the value of the GPIO_DEBOUNCINGTIME[7:0].DEBOUNCETIME bit field is from 0 to 255. But now omap2_set_gpio_debounce() will calculate debounce time and behave incorrectly in the following cases: 1) requested debounce time is !0 and <32 calculated DEBOUNCETIME = 0x1 == 62 us; expected value of DEBOUNCETIME = 0x0 == 31us 2) requested debounce time is 0 calculated DEBOUNCETIME = 0x1 == 62 us; expected: disable debounce and DEBOUNCETIME = 0x0 3) requested debounce time is >32 and <63 calculated DEBOUNCETIME = 0x0 and debounce will be disabled; expected: enable debounce and DEBOUNCETIME = 0x1 == 62 us Hence, rework omap2_set_gpio_debounce() to fix above cases: 1) introduce local variable "enable" and use it to identify when debounce need to be enabled or disabled. Disable debounce if requested debounce time is 0. 2) use below formula for debounce time calculation: debounce = (DIV_ROUND_UP(debounce, 31) - 1) & 0xFF; Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com> Acked-by: Santosh Shilimkar <ssantosh@kernel.org> Tested-by: Tony Lindgren <tony@atomide.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/gpio')
-rw-r--r--drivers/gpio/gpio-omap.c19
1 files changed, 10 insertions, 9 deletions
diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
index 03fd111e2d17..9ed5a675564c 100644
--- a/drivers/gpio/gpio-omap.c
+++ b/drivers/gpio/gpio-omap.c
@@ -29,6 +29,7 @@
#include <linux/platform_data/gpio-omap.h>
#define OFF_MODE 1
+#define OMAP4_GPIO_DEBOUNCINGTIME_MASK 0xFF
static LIST_HEAD(omap_gpio_list);
@@ -204,8 +205,9 @@ static inline void omap_gpio_dbck_disable(struct gpio_bank *bank)
* @offset: the gpio number on this @bank
* @debounce: debounce time to use
*
- * OMAP's debounce time is in 31us steps so we need
- * to convert and round up to the closest unit.
+ * 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.
*/
static void omap2_set_gpio_debounce(struct gpio_bank *bank, unsigned offset,
unsigned debounce)
@@ -213,16 +215,15 @@ static void omap2_set_gpio_debounce(struct gpio_bank *bank, unsigned offset,
void __iomem *reg;
u32 val;
u32 l;
+ bool enable = !!debounce;
if (!bank->dbck_flag)
return;
- if (debounce < 32)
- debounce = 0x01;
- else if (debounce > 7936)
- debounce = 0xff;
- else
- debounce = (debounce / 0x1f) - 1;
+ if (enable) {
+ debounce = DIV_ROUND_UP(debounce, 31) - 1;
+ debounce &= OMAP4_GPIO_DEBOUNCINGTIME_MASK;
+ }
l = BIT(offset);
@@ -233,7 +234,7 @@ static void omap2_set_gpio_debounce(struct gpio_bank *bank, unsigned offset,
reg = bank->base + bank->regs->debounce_en;
val = readl_relaxed(reg);
- if (debounce)
+ if (enable)
val |= l;
else
val &= ~l;