* charu@xxxxxx <charu@xxxxxx> [091110 04:28]:
> From: Charulatha V <charu@xxxxxx>
>
> This patch disables a GPIO module when all pins of a GPIO
> module are inactive (clock gating forced at module level) and
> enables the module when any gpio in the module is requested.
>
> The module is enabled only when "mod_usage" indicates that no GPIO
> in that module is currently active and the GPIO being requested
> is the 1st one to be active in that module.
>
> Each module would be disabled in omap_gpio_free() API when all
> GPIOs in a particular module becomes inactive. The module is
> re-enabled in omap_gpio_request() API when a GPIO is requested
> from the module that was previously disabled.
>
> Since individual GPIO's bookkeeping is added in this patch
> via "mod_usage", the same is used in omap_set_gpio_debounce()
> & omap_set_gpio_debounce_time() APIs to ensure that the gpio being
> used is actually "requested" prior to being used (Nishant Menon's
> Suggestion <nm@xxxxxx>)
>
> GPIO module level details are specific to hardware and hence
> introducing this patch in low level layer (plat-omap/gpio.c)
Looks like this needs to be refreshed against current for-next
branch in linux-omap.
Regards,
Tony
> Signed-off-by: Charulatha V <charu@xxxxxx>
> Acked-by: Nishanth Menon <nm@xxxxxx>
> ---
> arch/arm/plat-omap/gpio.c | 32 ++++++++++++++++++++++++++++++++
> 1 files changed, 32 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/plat-omap/gpio.c b/arch/arm/plat-omap/gpio.c
> index 4c35f9f..06a391b 100644
> --- a/arch/arm/plat-omap/gpio.c
> +++ b/arch/arm/plat-omap/gpio.c
> @@ -199,6 +199,7 @@ struct gpio_bank {
> struct gpio_chip chip;
> struct clk *dbck;
> u32 dbck_enable_mask;
> + u32 mod_usage;
> };
>
> #define METHOD_MPUIO 0
> @@ -690,6 +691,10 @@ void omap_set_gpio_debounce(int gpio, int enable)
> #else
> reg += OMAP24XX_GPIO_DEBOUNCE_EN;
> #endif
> + if (!(bank->mod_usage & l)) {
> + printk(KERN_ERR "GPIO %d not requested\n", gpio);
> + return;
> + }
>
> spin_lock_irqsave(&bank->lock, flags);
> val = __raw_readl(reg);
> @@ -726,6 +731,11 @@ void omap_set_gpio_debounce_time(int gpio, int enc_time)
> bank = get_gpio_bank(gpio);
> reg = bank->base;
>
> + if (!bank->mod_usage) {
> + printk(KERN_ERR "GPIO not requested\n");
> + return;
> + }
> +
> enc_time &= 0xff;
> #ifdef CONFIG_ARCH_OMAP4
> reg += OMAP4_GPIO_DEBOUNCINGTIME;
> @@ -1219,6 +1229,16 @@ static int omap_gpio_request(struct gpio_chip *chip, unsigned offset)
> __raw_writel(__raw_readl(reg) | (1 << offset), reg);
> }
> #endif
> + if (!cpu_class_is_omap1()) {
> + if (!bank->mod_usage) {
> + u32 ctrl;
> + ctrl = __raw_readl(bank->base + OMAP24XX_GPIO_CTRL);
> + ctrl &= 0xFFFFFFFE;
> + /* Module is enabled, clocks are not gated */
> + __raw_writel(ctrl, bank->base + OMAP24XX_GPIO_CTRL);
> + }
> + bank->mod_usage |= 1 << offset;
> + }
> spin_unlock_irqrestore(&bank->lock, flags);
>
> return 0;
> @@ -1245,6 +1265,16 @@ static void omap_gpio_free(struct gpio_chip *chip, unsigned offset)
> __raw_writel(1 << offset, reg);
> }
> #endif
> + if (!cpu_class_is_omap1()) {
> + bank->mod_usage &= ~(1 << offset);
> + if (!bank->mod_usage) {
> + u32 ctrl;
> + 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);
> }
> @@ -1879,6 +1909,8 @@ static int __init _omap_gpio_init(void)
> gpio_count = 32;
> }
> #endif
> +
> + bank->mod_usage = 0;
> /* REVISIT eventually switch from OMAP-specific gpio structs
> * over to the generic ones
> */
> --
> 1.6.0.4
>
> --
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