Message-Id: <1290628432-28765-2-git-send-email-gbean@codeaurora.org>
Date:	Wed, 24 Nov 2010 11:53:52 -0800
From:	Gregory Bean <gbean@...eaurora.org>
To:	dwalker@...eaurora.org
Cc:	linux-arm-msm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Gregory Bean <gbean@...eaurora.org>
Subject: [PATCH v5 2/2] msm: gpio: Add irq support to v2 gpiolib.

Complete the MSM v2 gpio subsystem by adding irq_chip.

Signed-off-by: Gregory Bean <gbean@...eaurora.org>
---
 v5 - miscellaneous cleanup, per dwalker@...eaurora.org
 v4 - miscellaneous cleanup to patch 1/2, per pkondeti@...eaurora.org
 v3 - miscellaneous cleanup to patch 1/2, per baruch@...s.co.il
 v2 - miscellaneous cleanup to patch 1/2, per baruch@...s.co.il

 arch/arm/mach-msm/gpio-v2.c |  309 +++++++++++++++++++++++++++++++++++++++----
 1 files changed, 286 insertions(+), 23 deletions(-)

diff --git a/arch/arm/mach-msm/gpio-v2.c b/arch/arm/mach-msm/gpio-v2.c
index d907af6..0de19ec 100644
--- a/arch/arm/mach-msm/gpio-v2.c
+++ b/arch/arm/mach-msm/gpio-v2.c
@@ -15,7 +15,13 @@
  * 02110-1301, USA.
  *
  */
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
+#include <linux/bitmap.h>
+#include <linux/bitops.h>
 #include <linux/gpio.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/irq.h>
 #include <linux/module.h>
@@ -27,29 +33,103 @@
 /* Bits of interest in the GPIO_IN_OUT register.
  */
 enum {
-	GPIO_IN_BIT  = 0,
-	GPIO_OUT_BIT = 1
+	GPIO_IN  = 0,
+	GPIO_OUT = 1
+};
+
+/* Bits of interest in the GPIO_INTR_STATUS register.
+ */
+enum {
+	INTR_STATUS = 0,
 };
 
 /* Bits of interest in the GPIO_CFG register.
  */
 enum {
-	GPIO_OE_BIT = 9,
+	GPIO_OE = 9,
+};
+
+/* Bits of interest in the GPIO_INTR_CFG register.
+ * When a GPIO triggers, two separate decisions are made, controlled
+ * by two separate flags.
+ *
+ * - First, INTR_RAW_STATUS_EN controls whether or not the GPIO_INTR_STATUS
+ * register for that GPIO will be updated to reflect the triggering of that
+ * gpio.  If this bit is 0, this register will not be updated.
+ * - Second, INTR_ENABLE controls whether an interrupt is triggered.
+ *
+ * If INTR_ENABLE is set and INTR_RAW_STATUS_EN is NOT set, an interrupt
+ * can be triggered but the status register will not reflect it.
+ */
+enum {
+	INTR_ENABLE        = 0,
+	INTR_POL_CTL       = 1,
+	INTR_DECT_CTL      = 2,
+	INTR_RAW_STATUS_EN = 3,
+};
+
+/* Codes of interest in GPIO_INTR_CFG_SU.
+ */
+enum {
+	TARGET_PROC_SCORPION = 4,
+	TARGET_PROC_NONE     = 7,
 };
 
+
+#define GPIO_INTR_CFG_SU(gpio)    (MSM_TLMM_BASE + 0x0400 + (0x04 * (gpio)))
 #define GPIO_CONFIG(gpio)         (MSM_TLMM_BASE + 0x1000 + (0x10 * (gpio)))
 #define GPIO_IN_OUT(gpio)         (MSM_TLMM_BASE + 0x1004 + (0x10 * (gpio)))
+#define GPIO_INTR_CFG(gpio)       (MSM_TLMM_BASE + 0x1008 + (0x10 * (gpio)))
+#define GPIO_INTR_STATUS(gpio)    (MSM_TLMM_BASE + 0x100c + (0x10 * (gpio)))
+
+/**
+ * struct msm_gpio_dev: the MSM8660 SoC GPIO device structure
+ *
+ * @enabled_irqs: a bitmap used to optimize the summary-irq handler.  By
+ * keeping track of which gpios are unmasked as irq sources, we avoid
+ * having to do readl calls on hundreds of iomapped registers each time
+ * the summary interrupt fires in order to locate the active interrupts.
+ *
+ * @wake_irqs: a bitmap for tracking which interrupt lines are enabled
+ * as wakeup sources.  When the device is suspended, interrupts which are
+ * not wakeup sources are disabled.
+ *
+ * @dual_edge_irqs: a bitmap used to track which irqs are configured
+ * as dual-edge, as this is not supported by the hardware and requires
+ * some special handling in the driver.
+ */
+struct msm_gpio_dev {
+	struct gpio_chip gpio_chip;
+	DECLARE_BITMAP(enabled_irqs, NR_GPIO_IRQS);
+	DECLARE_BITMAP(wake_irqs, NR_GPIO_IRQS);
+	DECLARE_BITMAP(dual_edge_irqs, NR_GPIO_IRQS);
+};
 
 static DEFINE_SPINLOCK(tlmm_lock);
 
+static inline struct msm_gpio_dev *to_msm_gpio_dev(struct gpio_chip *chip)
+{
+	return container_of(chip, struct msm_gpio_dev, gpio_chip);
+}
+
+static inline void set_gpio_bits(unsigned n, void __iomem *reg)
+{
+	writel(readl(reg) | n, reg);
+}
+
+static inline void clear_gpio_bits(unsigned n, void __iomem *reg)
+{
+	writel(readl(reg) & ~n, reg);
+}
+
 static int msm_gpio_get(struct gpio_chip *chip, unsigned offset)
 {
-	return readl(GPIO_IN_OUT(offset)) & BIT(GPIO_IN_BIT);
+	return readl(GPIO_IN_OUT(offset)) & BIT(GPIO_IN);
 }
 
 static void msm_gpio_set(struct gpio_chip *chip, unsigned offset, int val)
 {
-	writel(val ? BIT(GPIO_OUT_BIT) : 0, GPIO_IN_OUT(offset));
+	writel(val ? BIT(GPIO_OUT) : 0, GPIO_IN_OUT(offset));
 }
 
 static int msm_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
@@ -57,8 +137,7 @@ static int msm_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
 	unsigned long irq_flags;
 
 	spin_lock_irqsave(&tlmm_lock, irq_flags);
-	writel(readl(GPIO_CONFIG(offset)) & ~BIT(GPIO_OE_BIT),
-		GPIO_CONFIG(offset));
+	clear_gpio_bits(BIT(GPIO_OE), GPIO_CONFIG(offset));
 	spin_unlock_irqrestore(&tlmm_lock, irq_flags);
 	return 0;
 }
@@ -71,8 +150,7 @@ static int msm_gpio_direction_output(struct gpio_chip *chip,
 
 	spin_lock_irqsave(&tlmm_lock, irq_flags);
 	msm_gpio_set(chip, offset, val);
-	writel(readl(GPIO_CONFIG(offset)) | BIT(GPIO_OE_BIT),
-		GPIO_CONFIG(offset));
+	set_gpio_bits(BIT(GPIO_OE), GPIO_CONFIG(offset));
 	spin_unlock_irqrestore(&tlmm_lock, irq_flags);
 	return 0;
 }
@@ -87,30 +165,215 @@ static void msm_gpio_free(struct gpio_chip *chip, unsigned offset)
 	msm_gpiomux_put(chip->base + offset);
 }
 
-static struct gpio_chip msm_gpio = {
-	.base             = 0,
-	.ngpio            = NR_GPIO_IRQS,
-	.direction_input  = msm_gpio_direction_input,
-	.direction_output = msm_gpio_direction_output,
-	.get              = msm_gpio_get,
-	.set              = msm_gpio_set,
-	.request          = msm_gpio_request,
-	.free             = msm_gpio_free,
+static int msm_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
+{
+	return MSM_GPIO_TO_INT(chip->base + offset);
+}
+
+static inline int msm_irq_to_gpio(struct gpio_chip *chip, unsigned irq)
+{
+	return irq - MSM_GPIO_TO_INT(chip->base);
+}
+
+static struct msm_gpio_dev msm_gpio = {
+	.gpio_chip = {
+		.base             = 0,
+		.ngpio            = NR_GPIO_IRQS,
+		.direction_input  = msm_gpio_direction_input,
+		.direction_output = msm_gpio_direction_output,
+		.get              = msm_gpio_get,
+		.set              = msm_gpio_set,
+		.to_irq           = msm_gpio_to_irq,
+		.request          = msm_gpio_request,
+		.free             = msm_gpio_free,
+	},
+};
+
+/* For dual-edge interrupts in software, since the hardware has no
+ * such support:
+ *
+ * At appropriate moments, this function may be called to flip the polarity
+ * settings of both-edge irq lines to try and catch the next edge.
+ *
+ * The attempt is considered successful if:
+ * - the status bit goes high, indicating that an edge was caught, or
+ * - the input value of the gpio doesn't change during the attempt.
+ * If the value changes twice during the process, that would cause the first
+ * test to fail but would force the second, as two opposite
+ * transitions would cause a detection no matter the polarity setting.
+ *
+ * The do-loop tries to sledge-hammer closed the timing hole between
+ * the initial value-read and the polarity-write - if the line value changes
+ * during that window, an interrupt is lost, the new polarity setting is
+ * incorrect, and the first success test will fail, causing a retry.
+ *
+ * Algorithm comes from Google's msmgpio driver, see mach-msm/gpio.c.
+ */
+static void msm_gpio_update_dual_edge_pos(unsigned gpio)
+{
+	int loop_limit = 100;
+	unsigned val, val2, intstat;
+
+	do {
+		val = readl(GPIO_IN_OUT(gpio)) & BIT(GPIO_IN);
+		if (val)
+			clear_gpio_bits(BIT(INTR_POL_CTL), GPIO_INTR_CFG(gpio));
+		else
+			set_gpio_bits(BIT(INTR_POL_CTL), GPIO_INTR_CFG(gpio));
+		val2 = readl(GPIO_IN_OUT(gpio)) & BIT(GPIO_IN);
+		intstat = readl(GPIO_INTR_STATUS(gpio)) & BIT(INTR_STATUS);
+		if (intstat || val == val2)
+			return;
+	} while (loop_limit-- > 0);
+	pr_err("dual-edge irq failed to stabilize, "
+	       "interrupts dropped. %#08x != %#08x\n",
+	       val, val2);
+}
+
+static void msm_gpio_irq_ack(unsigned int irq)
+{
+	int gpio = msm_irq_to_gpio(&msm_gpio.gpio_chip, irq);
+
+	writel(BIT(INTR_STATUS), GPIO_INTR_STATUS(gpio));
+	if (test_bit(gpio, msm_gpio.dual_edge_irqs))
+		msm_gpio_update_dual_edge_pos(gpio);
+}
+
+static void msm_gpio_irq_mask(unsigned int irq)
+{
+	int gpio = msm_irq_to_gpio(&msm_gpio.gpio_chip, irq);
+	unsigned long irq_flags;
+
+	spin_lock_irqsave(&tlmm_lock, irq_flags);
+	writel(TARGET_PROC_NONE, GPIO_INTR_CFG_SU(gpio));
+	clear_gpio_bits(INTR_RAW_STATUS_EN | INTR_ENABLE, GPIO_INTR_CFG(gpio));
+	__clear_bit(gpio, msm_gpio.enabled_irqs);
+	spin_unlock_irqrestore(&tlmm_lock, irq_flags);
+}
+
+static void msm_gpio_irq_unmask(unsigned int irq)
+{
+	int gpio = msm_irq_to_gpio(&msm_gpio.gpio_chip, irq);
+	unsigned long irq_flags;
+
+	spin_lock_irqsave(&tlmm_lock, irq_flags);
+	__set_bit(gpio, msm_gpio.enabled_irqs);
+	set_gpio_bits(INTR_RAW_STATUS_EN | INTR_ENABLE, GPIO_INTR_CFG(gpio));
+	writel(TARGET_PROC_SCORPION, GPIO_INTR_CFG_SU(gpio));
+	spin_unlock_irqrestore(&tlmm_lock, irq_flags);
+}
+
+static int msm_gpio_irq_set_type(unsigned int irq, unsigned int flow_type)
+{
+	int gpio = msm_irq_to_gpio(&msm_gpio.gpio_chip, irq);
+	unsigned long irq_flags;
+	uint32_t bits;
+
+	spin_lock_irqsave(&tlmm_lock, irq_flags);
+
+	bits = readl(GPIO_INTR_CFG(gpio));
+
+	if (flow_type & IRQ_TYPE_EDGE_BOTH) {
+		bits |= BIT(INTR_DECT_CTL);
+		irq_desc[irq].handle_irq = handle_edge_irq;
+		if ((flow_type & IRQ_TYPE_EDGE_BOTH) == IRQ_TYPE_EDGE_BOTH)
+			__set_bit(gpio, msm_gpio.dual_edge_irqs);
+		else
+			__clear_bit(gpio, msm_gpio.dual_edge_irqs);
+	} else {
+		bits &= ~BIT(INTR_DECT_CTL);
+		irq_desc[irq].handle_irq = handle_level_irq;
+		__clear_bit(gpio, msm_gpio.dual_edge_irqs);
+	}
+
+	if (flow_type & (IRQ_TYPE_EDGE_RISING | IRQ_TYPE_LEVEL_HIGH))
+		bits |= BIT(INTR_POL_CTL);
+	else
+		bits &= ~BIT(INTR_POL_CTL);
+
+	writel(bits, GPIO_INTR_CFG(gpio));
+
+	if ((flow_type & IRQ_TYPE_EDGE_BOTH) == IRQ_TYPE_EDGE_BOTH)
+		msm_gpio_update_dual_edge_pos(gpio);
+
+	spin_unlock_irqrestore(&tlmm_lock, irq_flags);
+
+	return 0;
+}
+
+/*
+ * When the summary IRQ is raised, any number of GPIO lines may be high.
+ * It is the job of the summary handler to find all those GPIO lines
+ * which have been set as summary IRQ lines and which are triggered,
+ * and to call their interrupt handlers.
+ */
+static void msm_summary_irq_handler(unsigned int irq, struct irq_desc *desc)
+{
+	unsigned long i;
+
+	for (i = find_first_bit(msm_gpio.enabled_irqs, NR_GPIO_IRQS);
+	     i < NR_GPIO_IRQS;
+	     i = find_next_bit(msm_gpio.enabled_irqs, NR_GPIO_IRQS, i + 1)) {
+		if (readl(GPIO_INTR_STATUS(i)) & BIT(INTR_STATUS))
+			generic_handle_irq(msm_gpio_to_irq(&msm_gpio.gpio_chip,
+							   i));
+	}
+	desc->chip->ack(irq);
+}
+
+static int msm_gpio_irq_set_wake(unsigned int irq, unsigned int on)
+{
+	int gpio = msm_irq_to_gpio(&msm_gpio.gpio_chip, irq);
+
+	if (on) {
+		if (bitmap_empty(msm_gpio.wake_irqs, NR_GPIO_IRQS))
+			set_irq_wake(TLMM_SCSS_SUMMARY_IRQ, 1);
+		set_bit(gpio, msm_gpio.wake_irqs);
+	} else {
+		clear_bit(gpio, msm_gpio.wake_irqs);
+		if (bitmap_empty(msm_gpio.wake_irqs, NR_GPIO_IRQS))
+			set_irq_wake(TLMM_SCSS_SUMMARY_IRQ, 0);
+	}
+
+	return 0;
+}
+
+static struct irq_chip msm_gpio_irq_chip = {
+	.name		= "msmgpio",
+	.mask		= msm_gpio_irq_mask,
+	.unmask		= msm_gpio_irq_unmask,
+	.ack		= msm_gpio_irq_ack,
+	.set_type	= msm_gpio_irq_set_type,
+	.set_wake	= msm_gpio_irq_set_wake,
 };
 
 static int __devinit msm_gpio_probe(struct platform_device *dev)
 {
-	int ret;
+	int i, irq, ret;
+
+	bitmap_zero(msm_gpio.enabled_irqs, NR_GPIO_IRQS);
+	bitmap_zero(msm_gpio.wake_irqs, NR_GPIO_IRQS);
+	bitmap_zero(msm_gpio.dual_edge_irqs, NR_GPIO_IRQS);
+	msm_gpio.gpio_chip.label = dev->name;
+	ret = gpiochip_add(&msm_gpio.gpio_chip);
+	if (ret < 0)
+		return ret;
 
-	msm_gpio.label = dev->name;
-	ret = gpiochip_add(&msm_gpio);
+	for (i = 0; i < msm_gpio.gpio_chip.ngpio; ++i) {
+		irq = msm_gpio_to_irq(&msm_gpio.gpio_chip, i);
+		set_irq_chip(irq, &msm_gpio_irq_chip);
+		set_irq_handler(irq, handle_level_irq);
+		set_irq_flags(irq, IRQF_VALID);
+	}
 
-	return ret;
+	set_irq_chained_handler(TLMM_SCSS_SUMMARY_IRQ,
+				msm_summary_irq_handler);
+	return 0;
 }
 
 static int __devexit msm_gpio_remove(struct platform_device *dev)
 {
-	int ret = gpiochip_remove(&msm_gpio);
+	int ret = gpiochip_remove(&msm_gpio.gpio_chip);
 
 	if (ret < 0)
 		return ret;
-- 
1.7.0.4

-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
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