From 5c093aaf76600ca853035c07db095b48b34f40ba Mon Sep 17 00:00:00 2001
From: Alfred Klomp <git@alfredklomp.com>
Date: Sun, 13 Mar 2016 12:59:58 +0100
Subject: [PATCH 1/8] gpio: generate bank and mask values with a macro

Easier to read.
---
 Demo/Drivers/gpio.c | 64 +++++++++++++++++++++++++--------------------
 1 file changed, 36 insertions(+), 28 deletions(-)

diff --git a/Demo/Drivers/gpio.c b/Demo/Drivers/gpio.c
index 485de89..e16c335 100644
--- a/Demo/Drivers/gpio.c
+++ b/Demo/Drivers/gpio.c
@@ -5,6 +5,9 @@
 
 #include "gpio.h"
 
+#define BANK(pin)	((pin) >> 5)
+#define MASK(pin)	(1UL << ((pin) & 0x1F))
+
 typedef struct {
 	unsigned long	GPFSEL[6];	///< Function selection registers.
 	unsigned long	Reserved_1;
@@ -52,44 +55,49 @@ void SetGpioDirection(unsigned int pinNum, enum GPIO_DIR dir) {
 	SetGpioFunction(pinNum,dir);
 }
 
-void SetGpio(unsigned int pinNum, unsigned int pinVal) {
-	unsigned long offset=pinNum/32;
-	unsigned long mask=(1<<(pinNum%32));
+void SetGpio(unsigned int pinNum, unsigned int pinVal)
+{
+	unsigned long bank = BANK(pinNum);
+	unsigned long mask = MASK(pinNum);
 
 	if(pinVal) {
-		pRegs->GPSET[offset]|=mask;
+		pRegs->GPSET[bank] |= mask;
 	} else {
-		pRegs->GPCLR[offset]|=mask;
+		pRegs->GPCLR[bank] |= mask;
 	}
 }
 
-int ReadGpio(unsigned int pinNum) {
-	return ((pRegs->GPLEV[pinNum/32])>>(pinNum%32))&1;
+int ReadGpio(unsigned int pinNum)
+{
+	unsigned long bank = BANK(pinNum);
+	unsigned long mask = MASK(pinNum);
+
+	return ((pRegs->GPLEV[bank]) >> mask) & 1;
 }
 
 void EnableGpioDetect(unsigned int pinNum, enum DETECT_TYPE type)
 {
-	unsigned long mask=(1<<pinNum);
-	unsigned long offset=pinNum/32;
-	
+	unsigned long bank = BANK(pinNum);
+	unsigned long mask = MASK(pinNum);
+
 	switch(type) {
 	case DETECT_RISING:
-		pRegs->GPREN[offset]|=mask;
+		pRegs->GPREN[bank] |= mask;
 		break;
 	case DETECT_FALLING:
-		pRegs->GPFEN[offset]|=mask;
+		pRegs->GPFEN[bank] |= mask;
 		break;
 	case DETECT_HIGH:
-		pRegs->GPHEN[offset]|=mask;
+		pRegs->GPHEN[bank] |= mask;
 		break;
 	case DETECT_LOW:
-		pRegs->GPLEN[offset]|=mask;
+		pRegs->GPLEN[bank] |= mask;
 		break;
 	case DETECT_RISING_ASYNC:
-		pRegs->GPAREN[offset]|=mask;
+		pRegs->GPAREN[bank] |= mask;
 		break;
 	case DETECT_FALLING_ASYNC:
-		pRegs->GPAFEN[offset]|=mask;
+		pRegs->GPAFEN[bank] |= mask;
 		break;
 	case DETECT_NONE:
 		break;
@@ -98,27 +106,27 @@ void EnableGpioDetect(unsigned int pinNum, enum DETECT_TYPE type)
 
 void DisableGpioDetect(unsigned int pinNum, enum DETECT_TYPE type)
 {
-	unsigned long mask=~(1<<(pinNum%32));
-	unsigned long offset=pinNum/32;
-	
+	unsigned long bank = BANK(pinNum);
+	unsigned long mask = MASK(pinNum);
+
 	switch(type) {
 	case DETECT_RISING:
-		pRegs->GPREN[offset]&=mask;
+		pRegs->GPREN[bank] &= ~mask;
 		break;
 	case DETECT_FALLING:
-		pRegs->GPFEN[offset]&=mask;
+		pRegs->GPFEN[bank] &= ~mask;
 		break;
 	case DETECT_HIGH:
-		pRegs->GPHEN[offset]&=mask;
+		pRegs->GPHEN[bank] &= ~mask;
 		break;
 	case DETECT_LOW:
-		pRegs->GPLEN[offset]&=mask;
+		pRegs->GPLEN[bank] &= ~mask;
 		break;
 	case DETECT_RISING_ASYNC:
-		pRegs->GPAREN[offset]&=mask;
+		pRegs->GPAREN[bank] &= ~mask;
 		break;
 	case DETECT_FALLING_ASYNC:
-		pRegs->GPAFEN[offset]&=mask;
+		pRegs->GPAFEN[bank] &= ~mask;
 		break;
 	case DETECT_NONE:
 		break;
@@ -127,8 +135,8 @@ void DisableGpioDetect(unsigned int pinNum, enum DETECT_TYPE type)
 
 void ClearGpioInterrupt(unsigned int pinNum)
 {
-	unsigned long mask=(1<<(pinNum%32));
-	unsigned long offset=pinNum/32;
+	unsigned long bank = BANK(pinNum);
+	unsigned long mask = MASK(pinNum);
 
-	pRegs->GPEDS[offset]=mask;
+	pRegs->GPEDS[bank] = mask;
 }

From a8413eb7e66f48886fff16181445a86dd27f64a0 Mon Sep 17 00:00:00 2001
From: Alfred Klomp <git@alfredklomp.com>
Date: Wed, 9 Mar 2016 22:17:26 +0100
Subject: [PATCH 2/8] gpio: namespace functions as gpioSomething() for
 uniformity

Also mark constant parameters as `const' in function declarations.
---
 Demo/Drivers/gpio.c | 60 ++++++++++++++++++++++++---------------------
 Demo/Drivers/gpio.h | 29 +++++++++++-----------
 Demo/main.c         |  6 ++---
 3 files changed, 50 insertions(+), 45 deletions(-)

diff --git a/Demo/Drivers/gpio.c b/Demo/Drivers/gpio.c
index e16c335..e87f7ae 100644
--- a/Demo/Drivers/gpio.c
+++ b/Demo/Drivers/gpio.c
@@ -38,47 +38,49 @@ typedef struct {
 
 volatile BCM2835_GPIO_REGS * const pRegs = (BCM2835_GPIO_REGS *) (0x20200000);
 
-
-void SetGpioFunction(unsigned int pinNum, unsigned int funcNum) {
-
-	int offset = pinNum / 10;
+void
+gpioFunctionSet (const unsigned int pin, const unsigned int func)
+{
+	int offset = pin / 10;
 
 	unsigned long val = pRegs->GPFSEL[offset];	// Read in the original register value.
 
-	int item = pinNum % 10;
+	int item = pin % 10;
 	val &= ~(0x7 << (item * 3));
-	val |= ((funcNum & 0x7) << (item * 3));
+	val |= ((func & 0x7) << (item * 3));
 	pRegs->GPFSEL[offset] = val;
 }
 
-void SetGpioDirection(unsigned int pinNum, enum GPIO_DIR dir) {
-	SetGpioFunction(pinNum,dir);
+void
+gpioDirectionSet (const unsigned int pin, const enum GPIO_DIR dir)
+{
+	gpioFunctionSet(pin, dir);
 }
 
-void SetGpio(unsigned int pinNum, unsigned int pinVal)
+void
+gpioWrite (const unsigned int pin, const unsigned int val)
 {
-	unsigned long bank = BANK(pinNum);
-	unsigned long mask = MASK(pinNum);
+	unsigned long bank = BANK(pin);
+	unsigned long mask = MASK(pin);
 
-	if(pinVal) {
-		pRegs->GPSET[bank] |= mask;
-	} else {
-		pRegs->GPCLR[bank] |= mask;
-	}
+	val ? (pRegs->GPSET[bank] |= mask)
+	    : (pRegs->GPCLR[bank] |= mask);
 }
 
-int ReadGpio(unsigned int pinNum)
+unsigned int
+gpioRead (const unsigned int pin)
 {
-	unsigned long bank = BANK(pinNum);
-	unsigned long mask = MASK(pinNum);
+	unsigned long bank = BANK(pin);
+	unsigned long mask = MASK(pin);
 
 	return ((pRegs->GPLEV[bank]) >> mask) & 1;
 }
 
-void EnableGpioDetect(unsigned int pinNum, enum DETECT_TYPE type)
+void
+gpioDetectEnable (const unsigned int pin, const enum DETECT_TYPE type)
 {
-	unsigned long bank = BANK(pinNum);
-	unsigned long mask = MASK(pinNum);
+	unsigned long bank = BANK(pin);
+	unsigned long mask = MASK(pin);
 
 	switch(type) {
 	case DETECT_RISING:
@@ -104,10 +106,11 @@ void EnableGpioDetect(unsigned int pinNum, enum DETECT_TYPE type)
 	}
 }
 
-void DisableGpioDetect(unsigned int pinNum, enum DETECT_TYPE type)
+void
+gpioDetectDisable (const unsigned int pin, const enum DETECT_TYPE type)
 {
-	unsigned long bank = BANK(pinNum);
-	unsigned long mask = MASK(pinNum);
+	unsigned long bank = BANK(pin);
+	unsigned long mask = MASK(pin);
 
 	switch(type) {
 	case DETECT_RISING:
@@ -133,10 +136,11 @@ void DisableGpioDetect(unsigned int pinNum, enum DETECT_TYPE type)
 	}
 }
 
-void ClearGpioInterrupt(unsigned int pinNum)
+void
+gpioInterruptClear (const unsigned int pin)
 {
-	unsigned long bank = BANK(pinNum);
-	unsigned long mask = MASK(pinNum);
+	unsigned long bank = BANK(pin);
+	unsigned long mask = MASK(pin);
 
 	pRegs->GPEDS[bank] = mask;
 }
diff --git a/Demo/Drivers/gpio.h b/Demo/Drivers/gpio.h
index fa45970..767b2d2 100644
--- a/Demo/Drivers/gpio.h
+++ b/Demo/Drivers/gpio.h
@@ -26,23 +26,24 @@ enum GPIO_DIR {
 	GPIO_OUT
 };
 
-/* GPIO pin setup */
-void SetGpioFunction	(unsigned int pinNum, unsigned int funcNum);
-/* A simple wrapper around SetGpioFunction */
-void SetGpioDirection	(unsigned int pinNum, enum GPIO_DIR dir);
+// GPIO pin setup:
+void gpioFunctionSet (const unsigned int pin, const unsigned int func);
 
-/* Set GPIO output level */
-void SetGpio			(unsigned int pinNum, unsigned int pinVal);
+// A simple wrapper around SetGpioFunction:
+void gpioDirectionSet (const unsigned int pin, const enum GPIO_DIR dir);
 
-/* Read GPIO pin level */
-int ReadGpio			(unsigned int pinNum);
+// Set GPIO output level:
+void gpioWrite (const unsigned int pin, const unsigned int val);
 
-/* GPIO pull up/down resistor control function (NOT YET IMPLEMENTED) */
-int PudGpio				(unsigned int pinNum, enum PULL_STATE state);
+// Read GPIO pin level:
+unsigned int gpioRead (const unsigned int pin);
 
-/* Interrupt related functions */
-void EnableGpioDetect	(unsigned int pinNum, enum DETECT_TYPE type);
-void DisableGpioDetect	(unsigned int pinNum, enum DETECT_TYPE type);
-void ClearGpioInterrupt	(unsigned int pinNum);
+// GPIO pull up/down resistor control function (NOT YET IMPLEMENTED):
+int gpioPud (const unsigned int pin, const enum PULL_STATE state);
+
+// Interrupt related functions:
+void gpioDetectEnable   (const unsigned int pin, const enum DETECT_TYPE type);
+void gpioDetectDisable  (const unsigned int pin, const enum DETECT_TYPE type);
+void gpioInterruptClear (const unsigned int pin);
 
 #endif
diff --git a/Demo/main.c b/Demo/main.c
index 183a259..d3b1356 100644
--- a/Demo/main.c
+++ b/Demo/main.c
@@ -9,7 +9,7 @@ void task1(void *pParam) {
 	int i = 0;
 	while(1) {
 		i++;
-		SetGpio(16, 1);
+		gpioWrite(16, 1);
 		vTaskDelay(200);
 	}
 }
@@ -20,7 +20,7 @@ void task2(void *pParam) {
 	while(1) {
 		i++;
 		vTaskDelay(100);
-		SetGpio(16, 0);
+		gpioWrite(16, 0);
 		vTaskDelay(100);
 	}
 }
@@ -34,7 +34,7 @@ void task2(void *pParam) {
  **/
 void main (void)
 {
-	SetGpioFunction(16, 1);			// RDY led
+	gpioFunctionSet(16, 1);			// RDY led
 
 	xTaskCreate(task1, "LED_0", 128, NULL, 0, NULL);
 	xTaskCreate(task2, "LED_1", 128, NULL, 0, NULL);

From 32b6d8b4398793ed6040b5e1a08a0d37ba0b2497 Mon Sep 17 00:00:00 2001
From: Alfred Klomp <git@alfredklomp.com>
Date: Mon, 7 Mar 2016 00:04:34 +0100
Subject: [PATCH 3/8] gpio: use CamelCase for enum types, namespace properly

Use the 'Gpio' prefix for public GPIO enumerates.
---
 Demo/Drivers/gpio.c | 40 ++++++++++++++++++++-------------------
 Demo/Drivers/gpio.h | 46 ++++++++++++++++++++++-----------------------
 2 files changed, 44 insertions(+), 42 deletions(-)

diff --git a/Demo/Drivers/gpio.c b/Demo/Drivers/gpio.c
index e87f7ae..c9fb55b 100644
--- a/Demo/Drivers/gpio.c
+++ b/Demo/Drivers/gpio.c
@@ -52,7 +52,7 @@ gpioFunctionSet (const unsigned int pin, const unsigned int func)
 }
 
 void
-gpioDirectionSet (const unsigned int pin, const enum GPIO_DIR dir)
+gpioDirectionSet (const unsigned int pin, const enum GpioDir dir)
 {
 	gpioFunctionSet(pin, dir);
 }
@@ -77,61 +77,63 @@ gpioRead (const unsigned int pin)
 }
 
 void
-gpioDetectEnable (const unsigned int pin, const enum DETECT_TYPE type)
+gpioDetectEnable (const unsigned int pin, const enum GpioDetect type)
 {
 	unsigned long bank = BANK(pin);
 	unsigned long mask = MASK(pin);
 
-	switch(type) {
-	case DETECT_RISING:
+	switch (type)
+	{
+	case GPIO_DETECT_RISING:
 		pRegs->GPREN[bank] |= mask;
 		break;
-	case DETECT_FALLING:
+	case GPIO_DETECT_FALLING:
 		pRegs->GPFEN[bank] |= mask;
 		break;
-	case DETECT_HIGH:
+	case GPIO_DETECT_HIGH:
 		pRegs->GPHEN[bank] |= mask;
 		break;
-	case DETECT_LOW:
+	case GPIO_DETECT_LOW:
 		pRegs->GPLEN[bank] |= mask;
 		break;
-	case DETECT_RISING_ASYNC:
+	case GPIO_DETECT_RISING_ASYNC:
 		pRegs->GPAREN[bank] |= mask;
 		break;
-	case DETECT_FALLING_ASYNC:
+	case GPIO_DETECT_FALLING_ASYNC:
 		pRegs->GPAFEN[bank] |= mask;
 		break;
-	case DETECT_NONE:
+	case GPIO_DETECT_NONE:
 		break;
 	}
 }
 
 void
-gpioDetectDisable (const unsigned int pin, const enum DETECT_TYPE type)
+gpioDetectDisable (const unsigned int pin, const enum GpioDetect type)
 {
 	unsigned long bank = BANK(pin);
 	unsigned long mask = MASK(pin);
 
-	switch(type) {
-	case DETECT_RISING:
+	switch (type)
+	{
+	case GPIO_DETECT_RISING:
 		pRegs->GPREN[bank] &= ~mask;
 		break;
-	case DETECT_FALLING:
+	case GPIO_DETECT_FALLING:
 		pRegs->GPFEN[bank] &= ~mask;
 		break;
-	case DETECT_HIGH:
+	case GPIO_DETECT_HIGH:
 		pRegs->GPHEN[bank] &= ~mask;
 		break;
-	case DETECT_LOW:
+	case GPIO_DETECT_LOW:
 		pRegs->GPLEN[bank] &= ~mask;
 		break;
-	case DETECT_RISING_ASYNC:
+	case GPIO_DETECT_RISING_ASYNC:
 		pRegs->GPAREN[bank] &= ~mask;
 		break;
-	case DETECT_FALLING_ASYNC:
+	case GPIO_DETECT_FALLING_ASYNC:
 		pRegs->GPAFEN[bank] &= ~mask;
 		break;
-	case DETECT_NONE:
+	case GPIO_DETECT_NONE:
 		break;
 	}
 }
diff --git a/Demo/Drivers/gpio.h b/Demo/Drivers/gpio.h
index 767b2d2..2459c5a 100644
--- a/Demo/Drivers/gpio.h
+++ b/Demo/Drivers/gpio.h
@@ -1,36 +1,36 @@
 #ifndef _GPIO_H_
 #define _GPIO_H_
 
-/* GPIO event detect types */
-enum DETECT_TYPE {
-	DETECT_NONE,
-	DETECT_RISING,
-	DETECT_FALLING,
-	DETECT_HIGH,
-	DETECT_LOW,
-	DETECT_RISING_ASYNC,
-	DETECT_FALLING_ASYNC
+// GPIO event detect types
+enum GpioDetect {
+	GPIO_DETECT_NONE,
+	GPIO_DETECT_RISING,
+	GPIO_DETECT_FALLING,
+	GPIO_DETECT_HIGH,
+	GPIO_DETECT_LOW,
+	GPIO_DETECT_RISING_ASYNC,
+	GPIO_DETECT_FALLING_ASYNC,
 };
 
-/* GPIO pull up or down states */
-enum PULL_STATE {
-	PULL_DISABLE,
-	PULL_UP,
-	PULL_DOWN,
-	PULL_RESERVED
+// GPIO pull up or down states
+enum GpioPull {
+	GPIO_PULL_DISABLE,
+	GPIO_PULL_UP,
+	GPIO_PULL_DOWN,
+	GPIO_PULL_RESERVED,
 };
 
-/* Pin data direction */
-enum GPIO_DIR {
-	GPIO_IN,
-	GPIO_OUT
+// Pin data direction
+enum GpioDir {
+	GPIO_DIR_IN,
+	GPIO_DIR_OUT,
 };
 
 // GPIO pin setup:
 void gpioFunctionSet (const unsigned int pin, const unsigned int func);
 
 // A simple wrapper around SetGpioFunction:
-void gpioDirectionSet (const unsigned int pin, const enum GPIO_DIR dir);
+void gpioDirectionSet (const unsigned int pin, const enum GpioDir dir);
 
 // Set GPIO output level:
 void gpioWrite (const unsigned int pin, const unsigned int val);
@@ -39,11 +39,11 @@ void gpioWrite (const unsigned int pin, const unsigned int val);
 unsigned int gpioRead (const unsigned int pin);
 
 // GPIO pull up/down resistor control function (NOT YET IMPLEMENTED):
-int gpioPud (const unsigned int pin, const enum PULL_STATE state);
+int gpioPud (const unsigned int pin, const enum GpioPull state);
 
 // Interrupt related functions:
-void gpioDetectEnable   (const unsigned int pin, const enum DETECT_TYPE type);
-void gpioDetectDisable  (const unsigned int pin, const enum DETECT_TYPE type);
+void gpioDetectEnable   (const unsigned int pin, const enum GpioDetect type);
+void gpioDetectDisable  (const unsigned int pin, const enum GpioDetect type);
 void gpioInterruptClear (const unsigned int pin);
 
 #endif

From 5fff7a246f9e0d748b1c1660a7c72d63b0df033f Mon Sep 17 00:00:00 2001
From: Alfred Klomp <git@alfredklomp.com>
Date: Mon, 7 Mar 2016 00:54:35 +0100
Subject: [PATCH 4/8] gpio: detection: use data table

---
 Demo/Drivers/gpio.c | 113 +++++++++++++++-----------------------------
 Demo/Drivers/gpio.h |   1 -
 2 files changed, 39 insertions(+), 75 deletions(-)

diff --git a/Demo/Drivers/gpio.c b/Demo/Drivers/gpio.c
index c9fb55b..a0ef7b5 100644
--- a/Demo/Drivers/gpio.c
+++ b/Demo/Drivers/gpio.c
@@ -8,35 +8,35 @@
 #define BANK(pin)	((pin) >> 5)
 #define MASK(pin)	(1UL << ((pin) & 0x1F))
 
+// Base memory location for GPIO registers:
+#define GPIO_REG_BASE	0x20200000
+
+// Define a GPIO register:
+#define GPIO_REG(offs)	((volatile unsigned long *) (GPIO_REG_BASE + offs))
+
+// Pin event detection:
+#define GPREN		GPIO_REG (0x004C)
+#define GPFEN		GPIO_REG (0x0058)
+#define GPHEN		GPIO_REG (0x0064)
+#define GPLEN		GPIO_REG (0x0070)
+#define GPAREN		GPIO_REG (0x007C)
+#define GPAFEN		GPIO_REG (0x0088)
+
 typedef struct {
-	unsigned long	GPFSEL[6];	///< Function selection registers.
-	unsigned long	Reserved_1;
-	unsigned long	GPSET[2];
-	unsigned long	Reserved_2;
-	unsigned long	GPCLR[2];
-	unsigned long	Reserved_3;
-	unsigned long	GPLEV[2];
-	unsigned long	Reserved_4;
-	unsigned long	GPEDS[2];
-	unsigned long	Reserved_5;
-	unsigned long	GPREN[2];
-	unsigned long	Reserved_6;
-	unsigned long	GPFEN[2];
-	unsigned long	Reserved_7;
-	unsigned long	GPHEN[2];
-	unsigned long	Reserved_8;
-	unsigned long	GPLEN[2];
-	unsigned long	Reserved_9;
-	unsigned long	GPAREN[2];
-	unsigned long	Reserved_A;
-	unsigned long	GPAFEN[2];
-	unsigned long	Reserved_B;
-	unsigned long	GPPUD[1];
-	unsigned long	GPPUDCLK[2];
-	//Ignoring the reserved and test bytes
-} BCM2835_GPIO_REGS;
-
-volatile BCM2835_GPIO_REGS * const pRegs = (BCM2835_GPIO_REGS *) (0x20200000);
+	unsigned long GPFSEL[6];	///< Function selection registers.
+	unsigned long Reserved_1;
+	unsigned long GPSET[2];
+	unsigned long Reserved_2;
+	unsigned long GPCLR[2];
+	unsigned long Reserved_3;
+	unsigned long GPLEV[2];
+	unsigned long Reserved_4;
+	unsigned long GPEDS[2];
+	unsigned long Reserved_5;
+} __attribute__((packed))
+BCM2835_GPIO_REGS;
+
+volatile BCM2835_GPIO_REGS * const pRegs = (BCM2835_GPIO_REGS *) (GPIO_REG_BASE);
 
 void
 gpioFunctionSet (const unsigned int pin, const unsigned int func)
@@ -76,35 +76,22 @@ gpioRead (const unsigned int pin)
 	return ((pRegs->GPLEV[bank]) >> mask) & 1;
 }
 
+static volatile unsigned long *detect_map[] = {
+	[GPIO_DETECT_RISING]        = GPREN,
+	[GPIO_DETECT_FALLING]       = GPFEN,
+	[GPIO_DETECT_HIGH]          = GPHEN,
+	[GPIO_DETECT_LOW]           = GPLEN,
+	[GPIO_DETECT_RISING_ASYNC]  = GPAREN,
+	[GPIO_DETECT_FALLING_ASYNC] = GPAFEN,
+};
+
 void
 gpioDetectEnable (const unsigned int pin, const enum GpioDetect type)
 {
 	unsigned long bank = BANK(pin);
 	unsigned long mask = MASK(pin);
 
-	switch (type)
-	{
-	case GPIO_DETECT_RISING:
-		pRegs->GPREN[bank] |= mask;
-		break;
-	case GPIO_DETECT_FALLING:
-		pRegs->GPFEN[bank] |= mask;
-		break;
-	case GPIO_DETECT_HIGH:
-		pRegs->GPHEN[bank] |= mask;
-		break;
-	case GPIO_DETECT_LOW:
-		pRegs->GPLEN[bank] |= mask;
-		break;
-	case GPIO_DETECT_RISING_ASYNC:
-		pRegs->GPAREN[bank] |= mask;
-		break;
-	case GPIO_DETECT_FALLING_ASYNC:
-		pRegs->GPAFEN[bank] |= mask;
-		break;
-	case GPIO_DETECT_NONE:
-		break;
-	}
+	detect_map[type][bank] |= mask;
 }
 
 void
@@ -113,29 +100,7 @@ gpioDetectDisable (const unsigned int pin, const enum GpioDetect type)
 	unsigned long bank = BANK(pin);
 	unsigned long mask = MASK(pin);
 
-	switch (type)
-	{
-	case GPIO_DETECT_RISING:
-		pRegs->GPREN[bank] &= ~mask;
-		break;
-	case GPIO_DETECT_FALLING:
-		pRegs->GPFEN[bank] &= ~mask;
-		break;
-	case GPIO_DETECT_HIGH:
-		pRegs->GPHEN[bank] &= ~mask;
-		break;
-	case GPIO_DETECT_LOW:
-		pRegs->GPLEN[bank] &= ~mask;
-		break;
-	case GPIO_DETECT_RISING_ASYNC:
-		pRegs->GPAREN[bank] &= ~mask;
-		break;
-	case GPIO_DETECT_FALLING_ASYNC:
-		pRegs->GPAFEN[bank] &= ~mask;
-		break;
-	case GPIO_DETECT_NONE:
-		break;
-	}
+	detect_map[type][bank] &= ~mask;
 }
 
 void
diff --git a/Demo/Drivers/gpio.h b/Demo/Drivers/gpio.h
index 2459c5a..34b2957 100644
--- a/Demo/Drivers/gpio.h
+++ b/Demo/Drivers/gpio.h
@@ -3,7 +3,6 @@
 
 // GPIO event detect types
 enum GpioDetect {
-	GPIO_DETECT_NONE,
 	GPIO_DETECT_RISING,
 	GPIO_DETECT_FALLING,
 	GPIO_DETECT_HIGH,

From f062a9916ce90ef6ce3c05200ca0246350e453bd Mon Sep 17 00:00:00 2001
From: Alfred Klomp <git@alfredklomp.com>
Date: Mon, 7 Mar 2016 01:24:05 +0100
Subject: [PATCH 5/8] gpio: access registers through #define'd constructs

---
 Demo/Drivers/gpio.c | 42 ++++++++++++++++++++----------------------
 1 file changed, 20 insertions(+), 22 deletions(-)

diff --git a/Demo/Drivers/gpio.c b/Demo/Drivers/gpio.c
index a0ef7b5..a627d93 100644
--- a/Demo/Drivers/gpio.c
+++ b/Demo/Drivers/gpio.c
@@ -14,6 +14,19 @@
 // Define a GPIO register:
 #define GPIO_REG(offs)	((volatile unsigned long *) (GPIO_REG_BASE + offs))
 
+// Function selection:
+#define GPFSEL		GPIO_REG (0x0000)
+
+// Set and clear pins:
+#define GPSET		GPIO_REG (0x001C)
+#define GPCLR		GPIO_REG (0x0028)
+
+// Pin level readout:
+#define GPLEV		GPIO_REG (0x0034)
+
+// Pin event detection status:
+#define GPEDS		GPIO_REG (0x0040)
+
 // Pin event detection:
 #define GPREN		GPIO_REG (0x004C)
 #define GPFEN		GPIO_REG (0x0058)
@@ -22,33 +35,18 @@
 #define GPAREN		GPIO_REG (0x007C)
 #define GPAFEN		GPIO_REG (0x0088)
 
-typedef struct {
-	unsigned long GPFSEL[6];	///< Function selection registers.
-	unsigned long Reserved_1;
-	unsigned long GPSET[2];
-	unsigned long Reserved_2;
-	unsigned long GPCLR[2];
-	unsigned long Reserved_3;
-	unsigned long GPLEV[2];
-	unsigned long Reserved_4;
-	unsigned long GPEDS[2];
-	unsigned long Reserved_5;
-} __attribute__((packed))
-BCM2835_GPIO_REGS;
-
-volatile BCM2835_GPIO_REGS * const pRegs = (BCM2835_GPIO_REGS *) (GPIO_REG_BASE);
-
 void
 gpioFunctionSet (const unsigned int pin, const unsigned int func)
 {
 	int offset = pin / 10;
 
-	unsigned long val = pRegs->GPFSEL[offset];	// Read in the original register value.
+	// Read in the original register value:
+	unsigned long val = GPFSEL[offset];
 
 	int item = pin % 10;
 	val &= ~(0x7 << (item * 3));
 	val |= ((func & 0x7) << (item * 3));
-	pRegs->GPFSEL[offset] = val;
+	GPFSEL[offset] = val;
 }
 
 void
@@ -63,8 +61,8 @@ gpioWrite (const unsigned int pin, const unsigned int val)
 	unsigned long bank = BANK(pin);
 	unsigned long mask = MASK(pin);
 
-	val ? (pRegs->GPSET[bank] |= mask)
-	    : (pRegs->GPCLR[bank] |= mask);
+	val ? (GPSET[bank] |= mask)
+	    : (GPCLR[bank] |= mask);
 }
 
 unsigned int
@@ -73,7 +71,7 @@ gpioRead (const unsigned int pin)
 	unsigned long bank = BANK(pin);
 	unsigned long mask = MASK(pin);
 
-	return ((pRegs->GPLEV[bank]) >> mask) & 1;
+	return (GPLEV[bank] & mask) ? 1 : 0;
 }
 
 static volatile unsigned long *detect_map[] = {
@@ -109,5 +107,5 @@ gpioInterruptClear (const unsigned int pin)
 	unsigned long bank = BANK(pin);
 	unsigned long mask = MASK(pin);
 
-	pRegs->GPEDS[bank] = mask;
+	GPEDS[bank] = mask;
 }

From f1600786769f8b32a866d2cd21a0f4c234562c84 Mon Sep 17 00:00:00 2001
From: Alfred Klomp <git@alfredklomp.com>
Date: Tue, 8 Mar 2016 23:57:36 +0100
Subject: [PATCH 6/8] gpio: define all pin functions, add getter function

---
 Demo/Drivers/gpio.c | 31 ++++++++++++++++++++-----------
 Demo/Drivers/gpio.h | 22 ++++++++++++++--------
 Demo/main.c         |  2 +-
 3 files changed, 35 insertions(+), 20 deletions(-)

diff --git a/Demo/Drivers/gpio.c b/Demo/Drivers/gpio.c
index a627d93..85aca99 100644
--- a/Demo/Drivers/gpio.c
+++ b/Demo/Drivers/gpio.c
@@ -36,23 +36,32 @@
 #define GPAFEN		GPIO_REG (0x0088)
 
 void
-gpioFunctionSet (const unsigned int pin, const unsigned int func)
+gpioFunctionSet (const unsigned int pin, const enum GpioFunc func)
 {
-	int offset = pin / 10;
+	unsigned long bank = pin / 10;
+	unsigned long item = pin % 10;
+	unsigned long mask = 7UL << (item * 3);
 
-	// Read in the original register value:
-	unsigned long val = GPFSEL[offset];
+	// Get current register value:
+	unsigned long reg = GPFSEL[bank];
 
-	int item = pin % 10;
-	val &= ~(0x7 << (item * 3));
-	val |= ((func & 0x7) << (item * 3));
-	GPFSEL[offset] = val;
+	// Mask out the bits for this pin:
+	reg &= ~mask;
+
+	// Insert new bits for this pin:
+	reg |= (unsigned long)func << (item * 3);
+
+	// Store back:
+	GPFSEL[bank] = reg;
 }
 
-void
-gpioDirectionSet (const unsigned int pin, const enum GpioDir dir)
+enum GpioFunc
+gpioFunctionGet (const unsigned int pin)
 {
-	gpioFunctionSet(pin, dir);
+	unsigned long bank = pin / 10;
+	unsigned long item = pin % 10;
+
+	return (GPFSEL[bank] >> (item * 3)) & 7;
 }
 
 void
diff --git a/Demo/Drivers/gpio.h b/Demo/Drivers/gpio.h
index 34b2957..dc62fe2 100644
--- a/Demo/Drivers/gpio.h
+++ b/Demo/Drivers/gpio.h
@@ -19,17 +19,23 @@ enum GpioPull {
 	GPIO_PULL_RESERVED,
 };
 
-// Pin data direction
-enum GpioDir {
-	GPIO_DIR_IN,
-	GPIO_DIR_OUT,
+// Pin functions
+enum GpioFunc {
+	GPIO_FUNC_INPUT		= 0,	// Pin is input
+	GPIO_FUNC_OUTPUT	= 1,	// Pin is output
+	GPIO_FUNC_ALT_0		= 4,	// Alternative function 0
+	GPIO_FUNC_ALT_1		= 5,	// Alternative function 1
+	GPIO_FUNC_ALT_2		= 6,	// Alternative function 2
+	GPIO_FUNC_ALT_3		= 7,	// Alternative function 3
+	GPIO_FUNC_ALT_4		= 3,	// Alternative function 4
+	GPIO_FUNC_ALT_5		= 2,	// Alternative function 5
 };
 
-// GPIO pin setup:
-void gpioFunctionSet (const unsigned int pin, const unsigned int func);
+// Set GPIO pin function:
+void gpioFunctionSet (const unsigned int pin, const enum GpioFunc func);
 
-// A simple wrapper around SetGpioFunction:
-void gpioDirectionSet (const unsigned int pin, const enum GpioDir dir);
+// Get GPIO pin function:
+enum GpioFunc gpioFunctionGet (const unsigned int pin);
 
 // Set GPIO output level:
 void gpioWrite (const unsigned int pin, const unsigned int val);
diff --git a/Demo/main.c b/Demo/main.c
index d3b1356..a13c8b2 100644
--- a/Demo/main.c
+++ b/Demo/main.c
@@ -34,7 +34,7 @@ void task2(void *pParam) {
  **/
 void main (void)
 {
-	gpioFunctionSet(16, 1);			// RDY led
+	gpioFunctionSet(16, GPIO_FUNC_OUTPUT);		// RDY led
 
 	xTaskCreate(task1, "LED_0", 128, NULL, 0, NULL);
 	xTaskCreate(task2, "LED_1", 128, NULL, 0, NULL);

From e713318cb27bf117b34d055782746e73ef98567e Mon Sep 17 00:00:00 2001
From: Alfred Klomp <git@alfredklomp.com>
Date: Wed, 9 Mar 2016 22:15:21 +0100
Subject: [PATCH 7/8] gpio: rewrite event detection function

Return 0 if no event was detected, or 1 if one was. Reset the event bit
to restart the detection.
---
 Demo/Drivers/gpio.c | 14 +++++++++++---
 Demo/Drivers/gpio.h |  8 ++++----
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/Demo/Drivers/gpio.c b/Demo/Drivers/gpio.c
index 85aca99..cbca4d0 100644
--- a/Demo/Drivers/gpio.c
+++ b/Demo/Drivers/gpio.c
@@ -110,11 +110,19 @@ gpioDetectDisable (const unsigned int pin, const enum GpioDetect type)
 	detect_map[type][bank] &= ~mask;
 }
 
-void
-gpioInterruptClear (const unsigned int pin)
+unsigned int
+gpioDetected (const unsigned int pin)
 {
 	unsigned long bank = BANK(pin);
 	unsigned long mask = MASK(pin);
 
-	GPEDS[bank] = mask;
+	// No event if bit not set:
+	if (!(GPEDS[bank] & mask))
+		return 0;
+
+	// Clear event by setting bit to 1:
+	GPEDS[bank] |= mask;
+
+	// Confirm event:
+	return 1;
 }
diff --git a/Demo/Drivers/gpio.h b/Demo/Drivers/gpio.h
index dc62fe2..b906d29 100644
--- a/Demo/Drivers/gpio.h
+++ b/Demo/Drivers/gpio.h
@@ -46,9 +46,9 @@ unsigned int gpioRead (const unsigned int pin);
 // GPIO pull up/down resistor control function (NOT YET IMPLEMENTED):
 int gpioPud (const unsigned int pin, const enum GpioPull state);
 
-// Interrupt related functions:
-void gpioDetectEnable   (const unsigned int pin, const enum GpioDetect type);
-void gpioDetectDisable  (const unsigned int pin, const enum GpioDetect type);
-void gpioInterruptClear (const unsigned int pin);
+// Event detection functions:
+void gpioDetectEnable     (const unsigned int pin, const enum GpioDetect type);
+void gpioDetectDisable    (const unsigned int pin, const enum GpioDetect type);
+unsigned int gpioDetected (const unsigned int pin);
 
 #endif

From 6d282cdc1141fbfcbeb5bef3bf0debea453defdc Mon Sep 17 00:00:00 2001
From: Alfred Klomp <git@alfredklomp.com>
Date: Sun, 13 Mar 2016 20:09:23 +0100
Subject: [PATCH 8/8] gpio: implement gpioPull() for pull-up/down/none

---
 Demo/Drivers/gpio.c | 46 +++++++++++++++++++++++++++++++++++++++++++++
 Demo/Drivers/gpio.h | 12 ++++++------
 2 files changed, 52 insertions(+), 6 deletions(-)

diff --git a/Demo/Drivers/gpio.c b/Demo/Drivers/gpio.c
index cbca4d0..15cec85 100644
--- a/Demo/Drivers/gpio.c
+++ b/Demo/Drivers/gpio.c
@@ -35,6 +35,10 @@
 #define GPAREN		GPIO_REG (0x007C)
 #define GPAFEN		GPIO_REG (0x0088)
 
+// Pull up/down/none:
+#define GPPUD		GPIO_REG (0x0094)
+#define GPPUDCLK	GPIO_REG (0x0098)
+
 void
 gpioFunctionSet (const unsigned int pin, const enum GpioFunc func)
 {
@@ -126,3 +130,45 @@ gpioDetected (const unsigned int pin)
 	// Confirm event:
 	return 1;
 }
+
+static inline void
+wait (unsigned long cycles)
+{
+	// Each loop iteration takes three instructions:
+	cycles /= 3;
+
+	// Busy-wait by decrementing the cycle counter until it reaches zero:
+	asm volatile (
+		"1: sub %0, %0, #1  \n\t"
+		"   cmp %0, #0      \n\t"
+		"   bne 1b          \n\t"
+		:
+		: "r" (cycles)
+		: "cc"
+	);
+}
+
+void
+gpioPull (const unsigned int pin, const enum GpioPull type)
+{
+	unsigned long bank = BANK(pin);
+	unsigned long mask = MASK(pin);
+
+	// Setup direction register:
+	*GPPUD = type;
+
+	// Wait 150 cycles to set up the control signal:
+	wait(150);
+
+	// Activate clock signal for this pin:
+	GPPUDCLK[bank] |= mask;
+
+	// Wait 150 cycles to hold the control signal:
+	wait(150);
+
+	// Remove control signal:
+	*GPPUD = 0;
+
+	// Remove clock signal:
+	GPPUDCLK[bank] = 0;
+}
diff --git a/Demo/Drivers/gpio.h b/Demo/Drivers/gpio.h
index b906d29..c10c44e 100644
--- a/Demo/Drivers/gpio.h
+++ b/Demo/Drivers/gpio.h
@@ -13,10 +13,10 @@ enum GpioDetect {
 
 // GPIO pull up or down states
 enum GpioPull {
-	GPIO_PULL_DISABLE,
-	GPIO_PULL_UP,
-	GPIO_PULL_DOWN,
-	GPIO_PULL_RESERVED,
+	GPIO_PULL_DISABLE	= 0,
+	GPIO_PULL_DOWN		= 1,
+	GPIO_PULL_UP		= 2,
+	GPIO_PULL_RESERVED	= 3,
 };
 
 // Pin functions
@@ -43,8 +43,8 @@ void gpioWrite (const unsigned int pin, const unsigned int val);
 // Read GPIO pin level:
 unsigned int gpioRead (const unsigned int pin);
 
-// GPIO pull up/down resistor control function (NOT YET IMPLEMENTED):
-int gpioPud (const unsigned int pin, const enum GpioPull state);
+// GPIO pull-up/down/none:
+void gpioPull (const unsigned int pin, const enum GpioPull type);
 
 // Event detection functions:
 void gpioDetectEnable     (const unsigned int pin, const enum GpioDetect type);