> -----Original Message----- > From: linux-omap-owner@xxxxxxxxxxxxxxx > [mailto:linux-omap-owner@xxxxxxxxxxxxxxx] On Behalf Of charu@xxxxxx > Sent: Monday, November 09, 2009 7:56 PM > To: linux-omap@xxxxxxxxxxxxxxx > Cc: Varadarajan, Charu Latha > Subject: [PATCH V2] [OMAP] GPIO Module disable when all pins > are inactive > > 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. [sp] This para reads quite confusing. The subject talks of disable but this para indicates process for 'enable'. > > 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 introduced automatically > in this patch(mod_usage), the same is used in omap_set_gpio_debounce() [sp] Is book-keeping 'automatically introduced' or added in this patch? > & omap_set_gpio_debounce_time() APIs to ensure that the gpio being > used is actually "requested" prior to being used (Nishant Menon's > <nm@xxxxxx> Suggestion) > > Higher layer keeps track of GPIOs individually. This patch > introduces bookkeeping information, modulewise in lower layer > since disabling clock is done at module level. GPIO module level > details are specific to hardware and introducing APIs in higher > level layer to handle them might not be correct. Hence GPIO module > level information (mod_usage) has to be handled only in > low-level layer. [sp] Again the description seems to be quite confusing between the higher layer and lower layer contexts. > > Signed-off-by: Charulatha V <charu@xxxxxx> > Acked-by: Nishanth Menon <nm@xxxxxx> > --- > arch/arm/plat-omap/gpio.c | 35 +++++++++++++++++++++++++++++++++++ > 1 files changed, 35 insertions(+), 0 deletions(-) > > diff --git a/arch/arm/plat-omap/gpio.c b/arch/arm/plat-omap/gpio.c > index 4c35f9f..5ee6a60 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 > @@ -691,6 +692,12 @@ void omap_set_gpio_debounce(int gpio, int enable) > reg += OMAP24XX_GPIO_DEBOUNCE_EN; > #endif > > + if ((cpu_is_omap24xx() || cpu_is_omap34xx() || > cpu_is_omap44xx()) > + && (!(bank->mod_usage & l))) { [sp] Is the AND operation really needed? > + printk(KERN_ERR "GPIO not requested\n"); > + return; > + } > + > spin_lock_irqsave(&bank->lock, flags); > val = __raw_readl(reg); > > @@ -726,6 +733,12 @@ void omap_set_gpio_debounce_time(int > gpio, int enc_time) > bank = get_gpio_bank(gpio); > reg = bank->base; > > + if ((cpu_is_omap24xx() || cpu_is_omap34xx() || > cpu_is_omap44xx()) > + && (!bank->mod_usage)) { > + printk(KERN_ERR "GPIO not requested\n"); > + return; > + } > + > enc_time &= 0xff; > #ifdef CONFIG_ARCH_OMAP4 > reg += OMAP4_GPIO_DEBOUNCINGTIME; > @@ -1219,6 +1232,16 @@ 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()) { > + u32 ctrl; [sp] This should move into next "if" where it is used. > + if (!bank->mod_usage) { > + 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->mod_usage |= 1 << offset; > + } > spin_unlock_irqrestore(&bank->lock, flags); > > return 0; > @@ -1245,6 +1268,16 @@ 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()) { > + u32 ctrl; > + bank->mod_usage &= ~(1 << offset); > + if (!bank->mod_usage) { > + 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 +1912,8 @@ 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 > > -- > To unsubscribe from this list: send the line "unsubscribe > linux-omap" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
