1# RTC 2 3 4## Overview 5 6The real-time clock (RTC) is a real-time clock device in the operating system. In the Hardware Driver Foundation (HDF), the RTC uses the independent service mode for API adaptation. In this mode, each device independently publishes a service to process external access requests. When receiving an access request, the HDF DeviceManager extracts parameters from the request to call the internal APIs of the target device. In the independent service mode, the HDF DeviceManager provides service management capabilities. However, you need to configure a node for each device, which increases memory usage. 7 8 **Figure 1** Independent service mode 9 10  11 12 13## Available APIs 14 15**RtcMethod**: 16 17 18``` 19struct RtcMethod { 20 int32_t (*ReadTime)(struct RtcHost *host, struct RtcTime *time); 21 int32_t (*WriteTime)(struct RtcHost *host, const struct RtcTime *time); 22 int32_t (*ReadAlarm)(struct RtcHost *host, enum RtcAlarmIndex alarmIndex, struct RtcTime *time); 23 int32_t (*WriteAlarm)(struct RtcHost *host, enum RtcAlarmIndex alarmIndex, const struct RtcTime *time); 24 int32_t (*RegisterAlarmCallback)(struct RtcHost *host, enum RtcAlarmIndex alarmIndex, RtcAlarmCallback cb); 25 int32_t (*AlarmInterruptEnable)(struct RtcHost *host, enum RtcAlarmIndex alarmIndex, uint8_t enable); 26 int32_t (*GetFreq)(struct RtcHost *host, uint32_t *freq); 27 int32_t (*SetFreq)(struct RtcHost *host, uint32_t freq); 28 int32_t (*Reset)(struct RtcHost *host); 29 int32_t (*ReadReg)(struct RtcHost *host, uint8_t usrDefIndex, uint8_t *value); 30 int32_t (*WriteReg)(struct RtcHost *host, uint8_t usrDefIndex, uint8_t value); 31}; 32``` 33 34 **Table 1** Description of the callback functions in RtcMethod 35 36| Function| Input Parameter| Output Parameter| Return Value| Description| 37| -------- | -------- | -------- | -------- | -------- | 38| ReadTime | **host**: structure pointer to the RTC controller at the core layer.| **time**: structure pointer to the time read.| HDF_STATUS| Reads the RTC time.| 39| WriteTime | **host**: structure pointer to the RTC controller at the core layer.<br>**time**: structure pointer to the time to write.| –| HDF_STATUS| Writes the RTC time (including the year, month, day, day of week, hour, minute, second, and millisecond).| 40| ReadAlarm | **host**: structure pointer to the RTC controller at the core layer.<br>**alarmIndex**: RTC alarm index, which is an enumerated value.| **time**: structure pointer to the time read.| HDF_STATUS| Reads the RTC alarm time.| 41| WriteAlarm | **host**: structure pointer to the RTC controller at the core layer.<br>**alarmIndex**: RTC alarm index, which is an enumerated value.<br>**time**: structure pointer to the time to write.| –| HDF_STATUS| Writes the RTC alarm time.| 42| RegisterAlarmCallback | **host**: structure pointer to the RTC controller at the core layer.<br>**alarmIndex**: RTC alarm index, which is an enumerated value.<br>**cb**: pointer to the callback to register.| –| HDF_STATUS| Registers a callback to be invoked when an alarm is not generated at the specified time.| 43| AlarmInterruptEnable | **host**: structure pointer to the RTC controller at the core layer.<br>**alarmIndex**: RTC alarm index, which is an enumerated value.<br>**enable**: whether to enable interrupts for an RTC alarm. | –| HDF_STATUS| Enables or disables interrupts for an RTC alarm.| 44| GetFreq | **host**: structure pointer to the RTC controller at the core layer.| **freq**: pointer to the frequency obtained, which is of the uint32_t type.| HDF_STATUS| Obtains the frequency of the external crystal oscillator connected to the RTC driver.| 45| SetFreq | **host**: structure pointer to the RTC controller at the core layer.<br>**freq**: frequency to set, which is of the uint32_t type.| –| HDF_STATUS| Sets the frequency of the external crystal oscillator connected to the RTC driver.| 46| Reset | **host**: structure pointer to the RTC controller at the core layer.| –| HDF_STATUS| Resets the RTC.| 47| ReadReg | **host**: structure pointer to the RTC controller at the core layer.<br>**usrDefIndex**: index of a custom register.| **value**: pointer to the register value obtained, which is of the uint8_t type.| HDF_STATUS| Reads a custom RTC register. A register index corresponds to one byte of the register value.| 48| WriteReg | **host**: structure pointer to the RTC controller at the core layer.<br>**usrDefIndex**: index of a custom register.<br>**value**: register value to write, which is of the uint8_t type.| –| HDF_STATUS| Writes a custom RTC register. A register index corresponds to one byte of the register value.| 49 50 51## How to Develop 52 53The RTC module adaptation involves the following steps: 54 551. Instantiate the driver entry. 56 - Instantiate the **HdfDriverEntry** structure. 57 - Call **HDF_INIT** to register the **HdfDriverEntry** instance with the HDF. 58 592. Configure attribute files. 60 - Add the **deviceNode** information to the **device_info.hcs** file. 61 - (Optional) Add the **rtc_config.hcs** file. 62 633. Instantiate the RTC controller object. 64 - Initialize **RtcHost**. 65 - Instantiate **RtcMethod** in the **RtcHost** object. 66 >  **NOTE**<br> 67 > For details about the functions in **RtcMethod**, see [Available APIs](#available-apis). 68 694. Debug the driver. 70 (Optional) For new drivers, verify the basic functions, such as the RTC status control and response to interrupts. 71 72 73## Development Example 74 75The following uses **rtc_hi35xx.c** as an example to present the information required for implementing device functions. 76 771. Instantiate the driver entry.<br/>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. 78 Generally, the HDF calls the **Bind** function and then the **Init** function to load a driver. If **Init** fails to be called, the HDF calls **Release** to release driver resources and exit. 79 80 RTC driver entry example: 81 82 ``` 83 struct HdfDriverEntry g_rtcDriverEntry = { 84 .moduleVersion = 1, 85 .Bind = HiRtcBind, // See the Bind function. 86 .Init = HiRtcInit, // See the Init function. 87 .Release = HiRtcRelease, //See the Release function. 88 .moduleName = "HDF_PLATFORM_RTC", // (Mandatory) The value must be the same as that in the .hcs file. 89 }; 90 // Call HDF_INIT to register the driver entry with the HDF. 91 HDF_INIT(g_rtcDriverEntry); 92 ``` 93 942. Add the **deviceNode** information to the **device_info.hcs** file and configure the device attributes in the **rtc_config.hcs** file. 95 96 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 **RtcHost** members at the core layer. 97 In this example, there is only one RTC controller. If there are multiple RTC controllers, you need to add the **deviceNode** information to the **device_info** file and add the corresponding device attributes to the **rtc_config** file for each controller. 98 99 - **device_info.hcs** configuration example 100 101 102 ``` 103 root { 104 device_info { 105 platform :: host { 106 device_rtc :: device { 107 device0 :: deviceNode { 108 policy = 1; // The driver publishes services for kernel-mode processes only. 109 priority = 30; // A smaller value indicates a higher priority. 110 permission = 0644; // Permission for the driver to create a device node 111 moduleName = "HDF_PLATFORM_RTC"; // (Mandatory) Driver name, which must be the same as moduleName in the driver entry. 112 serviceName = "HDF_PLATFORM_RTC"; // (Mandatory) Unique name of the service published by the driver. 113 deviceMatchAttr = "hisilicon_hi35xx_rtc";// The value must be the same as that of match_attr in the .hcs file. 114 } 115 } 116 } 117 } 118 } 119 ``` 120 121 - **rtc_config.hcs** configuration example 122 123 124 ``` 125 root { 126 platform { 127 rtc_config { 128 controller_0x12080000 { 129 match_attr = "hisilicon_hi35xx_rtc";// (Mandatory) The value must be the same as that of deviceMatchAttr in device_info.hcs. 130 rtcSpiBaseAddr = 0x12080000; // Used for address mapping. 131 regAddrLength = 0x100; // Used for address mapping. 132 irq = 37; // Interrupt number. 133 supportAnaCtrl = false; 134 supportLock = false; 135 anaCtrlAddr = 0xff; 136 lock0Addr = 0xff; 137 lock1Addr = 0xff; 138 lock2Addr = 0xff; 139 lock3Addr = 0xff; 140 } 141 } 142 } 143 } 144 ``` 145 1463. Initialize the **RtcHost** object at the core layer, including defining a custom structure (to pass parameters and data) and implementing the **HdfDriverEntry** member functions (**Bind**, **Init** and **Release**) to instantiate **RtcMethod** in **RtcHost** (so that the underlying driver functions can be called). 147 - Defining a custom structure 148 149 To the driver, the custom structure holds parameters and data. The **DeviceResourceIface** method provided by the HDF reads the values in the **rtc_config.hcs** file to initialize the members in the custom structure. 150 151 152 ``` 153 struct RtcConfigInfo { 154 uint32_t spiBaseAddr; // Used for address mapping. 155 volatile void *remapBaseAddr; // Used for address mapping. 156 uint16_t regAddrLength; // Used for address mapping. 157 uint8_t supportAnaCtrl; // Whether ANACTRL is supported. 158 uint8_t supportLock; // Whether lock is supported. 159 uint8_t irq; // Interrupt number. 160 uint8_t alarmIndex; // RTC alarm index. 161 uint8_t anaCtrlAddr; // ANACTRL address. 162 struct RtcLockAddr lockAddr; // Lock address. 163 RtcAlarmCallback cb; // Callback. 164 struct OsalMutex mutex; // Mutex. 165 }; 166 167 // RtcHost is the controller structure at the core layer. The Init function assigns values to the members of RtcHost. 168 struct RtcHost { 169 struct IDeviceIoService service; 170 struct HdfDeviceObject *device; 171 struct RtcMethod *method; 172 void *data; 173 }; 174 ``` 175 - Instantiating **RtcMethod** in **RtcHost** (other members are initialized by **Init**) 176 177 178 ``` 179 // Example in rtc_hi35xx.c: instantiate the hook. 180 static struct RtcMethod g_method = { 181 .ReadTime = HiRtcReadTime, 182 .WriteTime = HiRtcWriteTime, 183 .ReadAlarm = HiReadAlarm, 184 .WriteAlarm = HiWriteAlarm, 185 .RegisterAlarmCallback = HiRegisterAlarmCallback, 186 .AlarmInterruptEnable = HiAlarmInterruptEnable, 187 .GetFreq = HiGetFreq, 188 .SetFreq = HiSetFreq, 189 .Reset = HiReset, 190 .ReadReg = HiReadReg, 191 .WriteReg = HiWriteReg, 192 }; 193 ``` 194 195 - **Bind** function 196 197 Input parameter: 198 199 **HdfDeviceObject**, an interface parameter exposed by the driver, contains the .hcs information. 200 201 Return value: 202 203 HDF_STATUS<br/>The table below describes some status. For more information, see **HDF_STATUS** in the **/drivers/framework/include/utils/hdf_base.h** file. 204 205 **Table 2** HDF_STATUS 206 207 | Status| Description| 208 | -------- | -------- | 209 | HDF_ERR_INVALID_OBJECT | Invalid controller object.| 210 | HDF_ERR_MALLOC_FAIL | Failed to allocate memory.| 211 | HDF_ERR_INVALID_PARAM | Invalid parameter.| 212 | HDF_ERR_IO | I/O error.| 213 | HDF_SUCCESS | Initialization successful.| 214 | HDF_FAILURE | Initialization failed.| 215 216 Function description: 217 218 Binds the **HdfDeviceObject** object and **RtcHost**. 219 220 221 ``` 222 static int32_t HiRtcBind(struct HdfDeviceObject *device) 223 { 224 struct RtcHost *host = NULL; 225 host = RtcHostCreate(device); // Allocate memory and attach the device host and the device. 226 // Prerequisite for conversion between HdfDeviceObject and RtcHost. 227 ... 228 device->service = &host->service; // Prerequisite for conversion between HdfDeviceObject and RtcHost. 229 // It helps implement the global host by calling RtcHostFromDevice. 230 return HDF_SUCCESS; 231 } 232 ``` 233 234 - **Init** function 235 236 Input parameter: 237 238 **HdfDeviceObject**, an interface parameter exposed by the driver, contains the .hcs information. 239 240 Return value: 241 242 HDF_STATUS 243 244 Function description: 245 246 Initializes the custom structure object and **RtcHost**. 247 248 249 ``` 250 static int32_t HiRtcInit(struct HdfDeviceObject *device) 251 { 252 struct RtcHost *host = NULL; 253 struct RtcConfigInfo *rtcInfo = NULL; 254 ... 255 host = RtcHostFromDevice(device);// Forcibly convert HdfDeviceObject to RtcHost. 256 rtcInfo = OsalMemCalloc(sizeof(*rtcInfo)); 257 ... 258 // HiRtcConfigData reads attributes from the device configuration tree and fills the values in supportAnaCtrl, supportLock, spiBaseAddr, regAddrLength, and irq in rtcInfo. 259 // Provide parameters for HiRtcSwInit and HiRtcSwInit. When HiRtcSwInit and HiRtcSwInit fail to be executed internally, operations such as memory release can be performed. 260 if (HiRtcConfigData(rtcInfo, device->property) != 0) { 261 ... 262 } 263 if (HiRtcSwInit(rtcInfo)! = 0) {// Address mapping and interrupt registration. 264 ... 265 } 266 if (HiRtcHwInit(rtcInfo)! = 0) {// Initialize ANACTRL and lockAddr. 267 ... 268 } 269 270 host->method = &g_method; // Attach the RtcMethod instance. 271 host->data = rtcInfo; // Prerequisites for conversion between RtcConfigInfo and RtcHost. 272 HDF_LOGI("Hdf dev service:%s init success!", HdfDeviceGetServiceName(device)); 273 return HDF_SUCCESS; 274 } 275 ``` 276 - **Release** function 277 278 Input parameter: 279 280 **HdfDeviceObject**, an interface parameter exposed by the driver, contains the .hcs information. 281 282 Return value: 283 284 No value is returned. 285 286 Function description: 287 288 Releases the memory and deletes the controller. This function assigns values to the **Release** function in the driver entry structure. If the HDF 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** or **Bind** function has the corresponding value assignment operations. 289 290 291 ``` 292 static void HiRtcRelease(struct HdfDeviceObject *device) 293 { 294 struct RtcHost *host = NULL; 295 struct RtcConfigInfo *rtcInfo = NULL; 296 ... 297 host = RtcHostFromDevice(device); // Forcibly convert HdfDeviceObject to RtcHost. 298 rtcInfo = (struct RtcConfigInfo *)host->data;// Forcibly convert RtcHost to RtcConfigInfo. 299 if (rtcInfo != NULL) { 300 HiRtcSwExit(rtcInfo); 301 OsalMemFree(rtcInfo); // Release RtcConfigInfo. 302 host->data = NULL; 303 } 304 RtcHostDestroy(host); // Release RtcHost. 305 } 306 ``` 307
