In the Hardware Driver Foundation \(HDF\) framework, the general-purpose input/output \(GPIO\) module uses the service-free mode for API adaptation. The service-free mode applies to the devices that do not provide user-mode APIs or the OS system that does not distinguish the user mode and the kernel mode. In the service-free mode, **DevHandle**\(a void pointer\) directly points to the kernel-mode address of the device object.
In the Hardware Driver Foundation \(HDF\) framework, the general-purpose input/output \(GPIO\) module uses the service-free mode for API adaptation. The service-free mode applies to the devices that do not provide user-mode APIs or the OS system that does not distinguish the user mode and the kernel mode. In the service-free mode, **DevHandle**\(a void pointer\) directly points to the kernel-mode address of the device object.
>For details, see [Available APIs](#section752964871810).
For details, see [Available APIs](#section752964871810)
4. Debug the driver.
-\(Optional\)For new drivers, verify the basic functions, such as the GPIO control status and response to interrupts.
4.\(Optional\)Debug the driver.
For new drivers, verify the basic functions, such as the GPIO control status and response to interrupts.
## Development Example<a name="section800425816103451"></a>
The following uses **gpio\_hi35xx.c** as an example to present the contents that need to be provided by the vendor to implement device functions.
The following uses **gpio\_hi35xx.c** as an example to present the contents that need to be provided by the vendor to implement device functions.
1. Instantiate the driver entry. The driver entry must be a global variable of the **HdfDriverEntry** type \(defined in **hdf\_device\_desc.h**\), and the value of **moduleName** must be the same as that in **device\_info.hcs**. In the HDF framework, the start address of each **HdfDriverEntry** object of all loaded drivers is collected to form a segment address space similar to an array for the upper layer to invoke.
1. Instantiate the driver entry. The driver entry must be a global variable of the **HdfDriverEntry** type \(defined in **hdf\_device\_desc.h**\), and the value of **moduleName** must be the same as that in **device\_info.hcs**. In the HDF framework, the start address of each **HdfDriverEntry** object of all loaded drivers is collected to form a segment address space similar to an array for the upper layer to invoke.
Generally, HDF calls the **Bind** function and then the **Init** function to load a driver. If **Init** fails to be called, HDF calls **Release** to release driver resources and exits.
Generally, HDF calls the **Bind** function and then the **Init** function to load a driver. If **Init** fails to be called, HDF calls **Release** to release driver resources and exits.
- GPIO driver entry reference
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@@ -193,11 +191,11 @@ The following uses **gpio\_hi35xx.c** as an example to present the contents th
HDF_INIT(g_gpioDriverEntry);
```
2. Add the **deviceNode** information to the **device\_info.hcs** file and configure the device attributes in the **gpio\_config.hcs** file. The **deviceNode** information is related to registration of the driver entry. The device attribute values are closely related to the default values or value ranges of the **GpioCntlr** members at the core layer.
2. Add the **deviceNode** information to the **device\_info.hcs** file and configure the device attributes in the **gpio\_config.hcs** file. The **deviceNode** information is related to registration of the driver entry. The device attribute values are closely related to the default values or value ranges of the **GpioCntlr** members at the core layer.
In this example, there is only one GPIO controller. If there are multiple GPIO controllers, you need to add the **deviceNode** information to the **device\_info** file and add the corresponding device attributes to the **gpio\_config** file.
In this example, there is only one GPIO controller. If there are multiple GPIO controllers, you need to add the **deviceNode** information to the **device\_info** file and add the corresponding device attributes to the **gpio\_config** file.
- **device\_info.hcs** configuration reference
- **device\_info.hcs** configuration reference
```
root {
...
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@@ -220,7 +218,7 @@ The following uses **gpio\_hi35xx.c** as an example to present the contents th
}
```
- **gpio\_config.hcs** configuration reference
- **gpio\_config.hcs** configuration reference
```
root {
...
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@@ -240,10 +238,10 @@ The following uses **gpio\_hi35xx.c** as an example to present the contents th
}
```
3. Initialize the **GpioCntlr** object at the core layer, including initializing the vendor custom structure \(transferring parameters and data\), instantiating **GpioMethod**\(used to call underlying functions of the driver\) in **GpioCntlr**, and implementing the **HdfDriverEntry** member functions \(**Bind**, **Init**, and **Release**\).
3. Initialize the **GpioCntlr** object at the core layer, including initializing the vendor custom structure \(transferring parameters and data\), instantiating **GpioMethod**\(used to call underlying functions of the driver\) in **GpioCntlr**, and implementing the **HdfDriverEntry** member functions \(**Bind**, **Init**, and**Release**\).
- Custom structure reference
To the driver, the custom structure carries parameters and data. The values in the **gpio\_config.hcs** file are read by HDF, and the structure members are initialized through **DeviceResourceIface**. Some important values, such as the index and the number of pins, are also passed to the **GpioCntlr** object at the core layer.
To the driver, the custom structure carries parameters and data. The values in the **gpio\_config.hcs** file are read by HDF, and the structure members are initialized through **DeviceResourceIface**. Some important values, such as the index and the number of pins, are also passed to the **GpioCntlr** object at the core layer.
```
struct Pl061GpioCntlr {
...
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@@ -279,7 +277,7 @@ The following uses **gpio\_hi35xx.c** as an example to present the contents th
};
```
- Instantiate the callback function structure **GpioMethod** in **GpioCntlr**. Other members are initialized by using the **Init** function.
- Instantiate the callback function structure **GpioMethod** in **GpioCntlr**. Other members are initialized by using the **Init** function.
```
// The members of the GpioMethod structure are all callbacks. Vendors need to implement the corresponding functions according to [Table 1](#table151341544111).
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@@ -304,13 +302,13 @@ The following uses **gpio\_hi35xx.c** as an example to present the contents th
Input parameters:
**HdfDeviceObject**, an interface parameter exposed by the driver, contains the .hcs configuration file information.
**HdfDeviceObject**, an interface parameter exposed by the driver, contains the .hcs configuration file information.
Return values:
HDF\_STATUS \(The following table lists some status. For details about other status, see **HDF\_STATUS** in the **//drivers/framework/include/utils/hdf\_base.h** file.\)
HDF\_STATUS \(The following table lists some status. For details about other status, see **HDF\_STATUS** in the **//drivers/framework/include/utils/hdf\_base.h** file.\)
@@ -354,7 +352,7 @@ The following uses **gpio\_hi35xx.c** as an example to present the contents th
Function description:
Initializes the custom structure object and **GpioCntlr**, calls the **GpioCntlrAdd** function at the core layer, and connects to the VFS \(optional\).
Initializes the custom structure object and **GpioCntlr**, calls the **GpioCntlrAdd** function at the core layer, and connects to the VFS \(optional\).
@@ -392,7 +390,7 @@ The following uses **gpio\_hi35xx.c** as an example to present the contents th
Input parameters:
**HdfDeviceObject**, an interface parameter exposed by the driver, contains the .hcs configuration file information.
**HdfDeviceObject**, an interface parameter exposed by the driver, contains the .hcs configuration file information.
Return values:
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@@ -400,7 +398,7 @@ The following uses **gpio\_hi35xx.c** as an example to present the contents th
Function description:
Releases the memory and deletes the controller. This function assigns a value to the **Release** API in the driver entry structure. When the HDF framework fails to call the **Init** function to initialize the driver, the **Release** function can be called to release driver resources. All forced conversion operations for obtaining the corresponding object can be successful only when the **Init** function has the corresponding value assignment operations.
Releases the memory and deletes the controller. This function assigns a value to the **Release** API in the driver entry structure. When the HDF framework fails to call the **Init** function to initialize the driver, the **Release** function can be called to release driver resources. All forced conversion operations for obtaining the corresponding object can be successful only when the **Init** function has the corresponding value assignment operations.
```
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@@ -421,8 +419,4 @@ The following uses **gpio\_hi35xx.c** as an example to present the contents th
OsalIoUnmap((void *)pl061->regBase);// (Mandatory) Remove the address mapping.
