Unit GPIO

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Description

GPIO devices represent the external or internal pins available on most system on chip (SoC) devices to provide control and interfacing capabilities for both hardware and software.

This unit maintains pin numbering exactly as per the SoC documentation but abstracts other features such as alternate function selects to avoid exposing chip specific values via the API.

Not all GPIO devices support the same feature set so the GPIODeviceProperties function returns a structure which describes the number of pins as well as minimum and maximum pin numbers along with a set of flags that indicate what functionality is supported by the device.

Multiple GPIO devices can be accomodated, each one is registered with this unit when the driver for the device is loaded and initialized. This unit includes functions for enumerating the devices that are available and each function takes a GPIODevice parameter to allow specifying the exact device to control.

Simplified versions of many of the functions in this unit are provided in the Platform unit to allow control of the default GPIO device and in cases where there is only one device registered these functions will provide most of the capability required.

Constants

To be documented

Type definitions

To be documented

Public variables

To be documented

Function declarations


Initialization functions 

procedure GPIOInit;
Description: To be documented
Note None documented


GPIO functions 

function GPIODeviceStart(GPIO:PGPIODevice):LongWord;
Description: Start the specified GPIO device and enable access
GPIO The GPIO device to start
Return ERROR_SUCCESS if completed or another error code on failure 


function GPIODeviceStop(GPIO:PGPIODevice):LongWord;
Description: Stop the specified GPIO device and disable access
GPIO The GPIO device to stop
Return ERROR_SUCCESS if completed or another error code on failure 


function GPIODeviceRead(GPIO:PGPIODevice; Reg:LongWord):LongWord;
Description: To be documented
Return The value of the memory register 


procedure GPIODeviceWrite(GPIO:PGPIODevice; Reg,Value:LongWord);
Description: Perform a direct write to a register of the specified GPIO device
GPIO The GPIO device to write to
Reg The memory register to write to
Return The value to write to the register 


function GPIODeviceInputGet(GPIO:PGPIODevice; Pin:LongWord):LongWord;
Description: Get the current state of an input pin on the specified GPIO device
Pin The pin to get the state for (eg GPIO_PIN_1)
Return The current state (eg GPIO_LEVEL_HIGH) or GPIO_LEVEL_UNKNOWN on failure 


function GPIODeviceInputWait(GPIO:PGPIODevice; Pin,Trigger,Timeout:LongWord):LongWord;
Description: Wait for the state of a input pin to change on the specified GPIO device
GPIO The GPIO device to wait for
Pin The pin to wait for the state to change (eg GPIO_PIN_1)
Trigger The trigger event to wait for (eg GPIO_TRIGGER_HIGH)
Timeout Number of milliseconds to wait for the change (INFINITE to wait forever)
Return The state after the change (eg GPIO_LEVEL_HIGH) or GPIO_LEVEL_UNKNOWN on failure or timeout 


function GPIODeviceInputEvent(GPIO:PGPIODevice; Pin,Trigger,Flags,Timeout:LongWord; Callback:TGPIOCallback; Data:Pointer):LongWord;
Description: Schedule a function to be called when the state of a input pin changes on the specified GPIO device
GPIO The GPIO device to schedule the callback for
Pin The pin to schedule the state change for (eg GPIO_PIN_1)
Trigger The trigger event which will cause the function to be called (eg GPIO_TRIGGER_HIGH)
Timeout The number of milliseconds before the scheduled trigger expires (INFINITE to never expire)
Callback The function to be called when the trigger occurs
Data A pointer to be pass to the function when the trigger occurs (Optional)
Return ERROR_SUCCESS if the trigger was scheduled successfully or another error code on failure
Note The pin and trigger that caused the event will be passed to the callback function 


function GPIODeviceInputCancel(GPIO:PGPIODevice; Pin:LongWord):LongWord;
Description: Cancel a previously scheduled event callback function for an input pin on the specified GPIO device
GPIO The GPIO device to cancel the callback for
Pin The pin to cancel the state change for (eg GPIO_PIN_1)
Return ERROR_SUCCESS if the callback was cancelled successfully or another error code on failure 


function GPIODeviceOutputSet(GPIO:PGPIODevice; Pin,Level:LongWord):LongWord;
Description: Set the state of a output pin on the specified GPIO device
GPIO The GPIO device to set for
Pin The pin to set the state for (eg GPIO_PIN_1)
Level The state to set the pin to (eg GPIO_LEVEL_HIGH)
Return ERROR_SUCCESS if completed successfully or another error code on failure 


function GPIODevicePullGet(GPIO:PGPIODevice;Pin:LongWord):LongWord;
Description: Get the current pull state of a pin on the specified GPIO device
Pin The pin to get the pull state for (eg GPIO_PIN_1)
Return The current pull state of the pin (eg GPIO_PULL_UP) or GPIO_PULL_UNKNOWN on failure 


function GPIODevicePullSelect(GPIO:PGPIODevice; Pin,Mode:LongWord):LongWord;
Description: Change the pull state of a pin on the specified GPIO device
GPIO The GPIO device to set for
Pin The pin to change the pull state for (eg GPIO_PIN_1)
Mode The pull state to set for the pin (eg GPIO_PULL_UP)
Return ERROR_SUCCESS if completed successfully or another error code on failure 


function GPIODeviceFunctionGet(GPIO:PGPIODevice; Pin:LongWord):LongWord;
Description: Get the current function of a pin on the specified GPIO device


function GPIODeviceFunctionSelect(GPIO:PGPIODevice; Pin,Mode:LongWord):LongWord;
Description: Change the function of a pin on the specified GPIO device
Pin The pin to get the function for (eg GPIO_PIN_1)
Return The current function of the pin (eg GPIO_FUNCTION_IN) or GPIO_FUNCTION_UNKNOWN on failure
GPIO The GPIO device to set for
Pin The pin to change the function for (eg GPIO_PIN_1)
Mode The function to set for the pin (eg GPIO_FUNCTION_OUT)
Return ERROR_SUCCESS if completed successfully or another error code on failure 


function GPIODeviceProperties(GPIO:PGPIODevice; Properties:PGPIOProperties):LongWord;
Description: Get the properties for the specified GPIO device
Properties Pointer to a TGPIOProperties structure to fill in
Return ERROR_SUCCESS if completed or another error code on failure 


function GPIODeviceCreate:PGPIODevice;
Description: Create a new GPIO entry
Return Pointer to new GPIO entry or nil if GPIO could not be created 


function GPIODeviceCreateEx(Size:LongWord):PGPIODevice;
Description: Create a new GPIO entry
Size Size in bytes to allocate for new GPIO (Including the GPIO entry)
Return Pointer to new GPIO entry or nil if GPIO could not be created 


function GPIODeviceDestroy(GPIO:PGPIODevice):LongWord;
Description: Destroy an existing GPIO entry
GPIO The GPIO device to destroy
Return ERROR_SUCCESS if completed or another error code on failure 


function GPIODeviceRegister(GPIO:PGPIODevice):LongWord;
Description: Register a new GPIO in the GPIO table
GPIO The GPIO device to register
Return ERROR_SUCCESS if completed or another error code on failure 


function GPIODeviceDeregister(GPIO:PGPIODevice):LongWord;
Description: Deregister a GPIO in the GPIO table
Return ERROR_SUCCESS if completed or another error code on failure 


function GPIODeviceFind(GPIOId:LongWord):PGPIODevice;
Description: Find a GPIO device by ID in the GPIO table
GPIOId The ID number of the GPIO device to find
Return Pointer to GPIO device entry or nil if not found 


function GPIODeviceFindByName(const Name:String):PGPIODevice; inline;
Description: Find a GPIO device by name in the GPIO table
Name The name of the GPIO to find (eg GPIO0)
Return Pointer to GPIO device entry or nil if not found 


function GPIODeviceFindByDescription(const Description:String):PGPIODevice; inline;
Description: To be documented
Note None documented 


function GPIODeviceEnumerate(Callback:TGPIOEnumerate; Data:Pointer):LongWord;
Description: To be documented
Note None documented 


function GPIODeviceNotification(GPIO:PGPIODevice; Callback:TGPIONotification; Data:Pointer; Notification,Flags:LongWord):LongWord;
Description: To be documented
Note None documented


RTL GPIO functions 

function SysGPIOAvailable:Boolean;
Description: Check if a GPIO device is available
Note None documented 


function SysGPIOInputGet(Pin:LongWord):LongWord;
Description: Get the current state of a GPIO input pin
Pin The pin to get the state for (eg GPIO_PIN_1)
Return The current state (eg GPIO_LEVEL_HIGH) or GPIO_LEVEL_UNKNOWN on failure 


function SysGPIOInputWait(Pin,Trigger,Timeout:LongWord):LongWord;
Description: Wait for the state of a GPIO input pin to change
Pin The pin to wait for the state to change (eg GPIO_PIN_1)
Trigger The trigger event to wait for (eg GPIO_TRIGGER_HIGH)
Timeout Number of milliseconds to wait for the change (INFINITE to wait forever)
Return The state after the change (eg GPIO_LEVEL_HIGH) or GPIO_LEVEL_UNKNOWN on failure or timeout 


function SysGPIOInputEvent(Pin,Trigger,Timeout:LongWord; Callback:TGPIOCallback; Data:Pointer):LongWord;
Description: Schedule a function to be called when the state of a GPIO input pin changes
Pin The pin to schedule the state change for (eg GPIO_PIN_1)
Trigger The trigger event which will cause the function to be called (eg GPIO_TRIGGER_HIGH)
Timeout The number of milliseconds before the scheduled trigger expires (INFINITE to never expire)
Callback The function to be called when the trigger occurs
Data A pointer to be pass to the function when the trigger occurs (Optional)
Return ERROR_SUCCESS if the trigger was scheduled successfully or another error code on failure
Note The pin and trigger that caused the event will be passed to the callback function 


function SysGPIOOutputSet(Pin,Level:LongWord):LongWord;
Description: Set the state of a GPIO output pin
Pin The pin to set the state for (eg GPIO_PIN_1)
Level The state to set the pin to (eg GPIO_LEVEL_HIGH)
Return ERROR_SUCCESS if completed successfully or another error code on failure 


function SysGPIOPullGet(Pin:LongWord):LongWord;
Description: Get the current pull state of a GPIO pin
Pin The pin to get the pull state for (eg GPIO_PIN_1)
Return The current pull state of the pin (eg GPIO_PULL_UP) or GPIO_PULL_UNKNOWN on failure 


function SysGPIOPullSelect(Pin,Mode:LongWord):LongWord;
Description: Change the pull state of a GPIO pin
Pin The pin to change the pull state for (eg GPIO_PIN_1)
Mode The pull state to set for the pin (eg GPIO_PULL_UP)
Return ERROR_SUCCESS if completed successfully or another error code on failure 


function SysGPIOFunctionGet(Pin:LongWord):LongWord;
Description: Get the current function of a GPIO pin
Pin The pin to get the function for (eg GPIO_PIN_1)
Return The current function of the pin (eg GPIO_FUNCTION_IN) or GPIO_FUNCTION_UNKNOWN on failure 


function SysGPIOFunctionSelect(Pin,Mode:LongWord):LongWord;
Description: Change the function of a GPIO pin
Pin The pin to change the function for (eg GPIO_PIN_1)
Mode The function to set for the pin (eg GPIO_FUNCTION_OUT)
Return ERROR_SUCCESS if completed successfully or another error code on failure


GPIO helper functions 

function GPIOGetCount:LongWord; inline;
Description: Get the current GPIO count
Note None documented 


function GPIODeviceGetDefault:PGPIODevice; inline;
Description: Get the current default GPIO device
Note None documented 


function GPIODeviceSetDefault(GPIO:PGPIODevice):LongWord;
Description: Set the current default GPIO device
Note None documented 


function GPIODeviceCheck(GPIO:PGPIODevice):PGPIODevice;
Description: Check if the supplied GPIO is in the GPIO table
Note None documented 


function GPIODeviceCreateEvent(GPIO:PGPIODevice; Pin:PGPIOPin; Callback:TGPIOCallback; Data:Pointer; Timeout:LongWord):PGPIOEvent;
Description: Create a new event using the supplied parameters
Note Event must be registered by calling GPIODeviceRegisterEvent. Caller must hold the GPIO device lock. 


function GPIODeviceDestroyEvent(GPIO:PGPIODevice; Event:PGPIOEvent):LongWord;
Description: Destroy an existing event
Note Event must be deregistered first by calling GPIODeviceDeregisterEvent. Caller must hold the GPIO device lock. 


function GPIODeviceRegisterEvent(GPIO:PGPIODevice; Pin:PGPIOPin; Event:PGPIOEvent):LongWord;
Description: Register an event in the event list of the supplied Pin
Note Event must be created by calling GPIODeviceCreateEvent. Caller must hold the GPIO device lock. 


function GPIODeviceDeregisterEvent(GPIO:PGPIODevice;Pin:PGPIOPin;Event:PGPIOEvent):LongWord;
Description: Deregister an event in the event list of the supplied Pin
Note Event must be destroyed by calling GPIODeviceDestroyEvent. Caller must hold the GPIO device lock. 


procedure GPIOLog(Level:LongWord; GPIO:PGPIODevice; const AText:String);
Description: To be documented
Note None documented 


procedure GPIOLogInfo(GPIO:PGPIODevice; const AText:String);
Description: To be documented
Note None documented 


procedure GPIOLogError(GPIO:PGPIODevice; const AText:String);
Description: To be documented
Note None documented 


procedure GPIOLogDebug(GPIO:PGPIODevice; const AText:String);
Description: To be documented
Note None documented 


function GPIOPinToString(Pin:LongWord):String;
Description: To be documented
Note None documented 


function GPIOLevelToString(Level:LongWord):String;
Description: To be documented
Note None documented 


function GPIOTriggerToString(Trigger:LongWord):String;
Description: To be documented
Note None documented 


function GPIOPullToString(Value:LongWord):String;
Description: To be documented
Note None documented 


function GPIOFunctionToString(Value:LongWord):String;
Description: To be documented
Note None documented


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