Varadarajan, Charu Latha had written, on 10/23/2009 10:55 AM, the following:
From: Charulatha V <charu@xxxxxx>
This patch disables a GPIO module when all the pins of GPIO
module are inactive (clock gating forced at module level) and
enables the module when any gpio in the module is requested.
Signed-off-by: Charulatha V <charu@xxxxxx>
---
arch/arm/plat-omap/gpio.c | 22 ++++++++++++++++++++++
1 files changed, 22 insertions(+), 0 deletions(-)
diff --git a/arch/arm/plat-omap/gpio.c b/arch/arm/plat-omap/gpio.c
index cdc2a58..2304a5d 100644
--- a/arch/arm/plat-omap/gpio.c
+++ b/arch/arm/plat-omap/gpio.c
@@ -194,6 +194,7 @@ struct gpio_bank {
spinlock_t lock;
struct gpio_chip chip;
struct clk *dbck;
+ u32 gpio_status;
please rename this as gpio_usage?
maybe OMAP1 could also benefit out of this..
};
#define METHOD_MPUIO 0
@@ -1080,6 +1081,7 @@ static int omap_gpio_request(struct gpio_chip *chip, unsigned offset)
{
struct gpio_bank *bank = container_of(chip, struct gpio_bank, chip);
unsigned long flags;
+ u32 ctrl = 0;
Remove this to the {} no point in wasting stack space when you dont need
to + you will generate warning for OMAP1 platforms.
spin_lock_irqsave(&bank->lock, flags);
@@ -1097,6 +1099,15 @@ static int omap_gpio_request(struct gpio_chip *chip, unsigned offset)
__raw_writel(__raw_readl(reg) | (1 << offset), reg);
}
#endif
+ if (cpu_is_omap24xx() || cpu_is_omap34xx() || cpu_is_omap44xx()) {
+ if (!bank->gpio_status) {
+ ctrl = __raw_readl(bank->base + OMAP24XX_GPIO_CTRL);
+ /* Module is enabled, clocks are not gated */
+ ctrl &= 0xFFFFFFFE;
+ __raw_writel(ctrl, bank->base + OMAP24XX_GPIO_CTRL);
+ }
+ bank->gpio_status |= 1 << offset;
+ }
why do this every time a gpio is enabled? why not do this iff gpio was
never used before.. how about the following:
if (!bank->gpio_status && (cpu_is_omap24xx() || cpu_is_omap34xx() ||
cpu_is_omap44xx())) {
u32 ctrl = __raw_readl(bank->base + OMAP24XX_GPIO_CTRL);
/* Module is enabled, clocks are not gated */
ctrl &= 0xFFFFFFFE;
__raw_writel(ctrl, bank->base + OMAP24XX_GPIO_CTRL);
}
bank->gpio_status |= 1 << offset;
spin_unlock_irqrestore(&bank->lock, flags);
return 0;
@@ -1106,6 +1117,7 @@ static void omap_gpio_free(struct gpio_chip *chip, unsigned offset)
{
struct gpio_bank *bank = container_of(chip, struct gpio_bank, chip);
unsigned long flags;
+ u32 ctrl = 0;
used just once -> move it to the {} + warning to OMAP1
spin_lock_irqsave(&bank->lock, flags);
#ifdef CONFIG_ARCH_OMAP16XX
@@ -1123,6 +1135,15 @@ static void omap_gpio_free(struct gpio_chip *chip, unsigned offset)
__raw_writel(1 << offset, reg);
}
#endif
+ if (cpu_is_omap24xx() || cpu_is_omap34xx() || cpu_is_omap44xx()) {
+ bank->gpio_status &= ~(1 << offset);
+ if (!bank->gpio_status) {
+ ctrl = __raw_readl(bank->base + OMAP24XX_GPIO_CTRL);
+ /* Module is disabled, clocks are gated */
+ ctrl |= 1;
+ __raw_writel(ctrl, bank->base + OMAP24XX_GPIO_CTRL);
+ }
+ }
how about this:
bank->gpio_status &= ~(1 << offset);
if (!bank->gpio_status && (cpu_is_omap24xx() || cpu_is_omap34xx() ||
cpu_is_omap44xx())) {
u32 ctrl = __raw_readl(bank->base + OMAP24XX_GPIO_CTRL);
/* Module is disabled, clocks are gated */
ctrl |= 1;
__raw_writel(ctrl, bank->base + OMAP24XX_GPIO_CTRL);
}
_reset_gpio(bank, bank->chip.base + offset);
spin_unlock_irqrestore(&bank->lock, flags);
}
@@ -1700,6 +1721,7 @@ static int __init _omap_gpio_init(void)
gpio_count = 32;
}
#endif
+ bank->gpio_status = 0;
/* REVISIT eventually switch from OMAP-specific gpio structs
* over to the generic ones
*/
Regards,
Nishanth Menon
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