[PATCH V2] [OMAP] GPIO Module disable when all pins are inactive

* [PATCH V2] [OMAP] GPIO Module disable when all pins are inactive
@ 2009-11-09 14:26 charu
  2009-11-09 14:42 ` Premi, Sanjeev
  2009-11-09 21:03 ` Tony Lindgren
  0 siblings, 2 replies; 4+ messages in thread
From: charu @ 2009-11-09 14:26 UTC (permalink / raw)
  To: linux-omap; +Cc: Charulatha V

From: Charulatha V <charu@ti.com>

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 introduced automatically
in this patch(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
<nm@ti.com> 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.

Signed-off-by: Charulatha V <charu@ti.com>
Acked-by: Nishanth Menon <nm@ti.com>
---
 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))) {
+		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;
+		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


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