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 71 (Optional) For new drivers, verify the basic functions, such as the RTC status control and response to interrupts. 72 73 74## Development Example 75 76The following uses **rtc_hi35xx.c** as an example to present the information required for implementing device functions. 77 781. Instantiate the driver entry. 79 80 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**. 81 82 In the HDF, 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. 83 84 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. 85 86 RTC driver entry example: 87 88 ``` 89 struct HdfDriverEntry g_rtcDriverEntry = { 90 .moduleVersion = 1, 91 .Bind = HiRtcBind, // See the Bind function. 92 .Init = HiRtcInit, // See the Init function. 93 .Release = HiRtcRelease, //See the Release function. 94 .moduleName = "HDF_PLATFORM_RTC", // (Mandatory) The value must be the same as that in the .hcs file. 95 }; 96 // Call HDF_INIT to register the driver entry with the HDF. 97 HDF_INIT(g_rtcDriverEntry); 98 ``` 99 1002. Add the **deviceNode** information to the **device_info.hcs** file and configure the device attributes in the **rtc_config.hcs** file. 101 102 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. 103 104 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. 105 106 - **device_info.hcs** configuration example 107 108 109 ``` 110 root { 111 device_info { 112 platform :: host { 113 device_rtc :: device { 114 device0 :: deviceNode { 115 policy = 1; // The driver publishes services for kernel-mode processes only. 116 priority = 30; // A smaller value indicates a higher priority. 117 permission = 0644; // Permission for the driver to create a device node 118 moduleName = "HDF_PLATFORM_RTC"; // (Mandatory) Driver name, which must be the same as moduleName in the driver entry. 119 serviceName = "HDF_PLATFORM_RTC"; // (Mandatory) Unique name of the service published by the driver. 120 deviceMatchAttr = "hisilicon_hi35xx_rtc";// The value must be the same as that of match_attr in the .hcs file. 121 } 122 } 123 } 124 } 125 } 126 ``` 127 128 - **rtc_config.hcs** configuration example 129 130 131 ``` 132 root { 133 platform { 134 rtc_config { 135 controller_0x12080000 { 136 match_attr = "hisilicon_hi35xx_rtc";// (Mandatory) The value must be the same as that of deviceMatchAttr in device_info.hcs. 137 rtcSpiBaseAddr = 0x12080000; // Used for address mapping. 138 regAddrLength = 0x100; // Used for address mapping. 139 irq = 37; // Interrupt number. 140 supportAnaCtrl = false; 141 supportLock = false; 142 anaCtrlAddr = 0xff; 143 lock0Addr = 0xff; 144 lock1Addr = 0xff; 145 lock2Addr = 0xff; 146 lock3Addr = 0xff; 147 } 148 } 149 } 150 } 151 ``` 152 1533. 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). 154 155 - Defining a custom structure 156 157 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. 158 159 ``` 160 struct RtcConfigInfo { 161 uint32_t spiBaseAddr; // Used for address mapping. 162 volatile void *remapBaseAddr; // Used for address mapping. 163 uint16_t regAddrLength; // Used for address mapping. 164 uint8_t supportAnaCtrl; // Whether ANACTRL is supported. 165 uint8_t supportLock; // Whether lock is supported. 166 uint8_t irq; // Interrupt number. 167 uint8_t alarmIndex; // RTC alarm index. 168 uint8_t anaCtrlAddr; // ANACTRL address. 169 struct RtcLockAddr lockAddr; // Lock address. 170 RtcAlarmCallback cb; // Callback. 171 struct OsalMutex mutex; // Mutex. 172 }; 173 174 // RtcHost is the controller structure at the core layer. The Init function assigns values to the members of RtcHost. 175 struct RtcHost { 176 struct IDeviceIoService service; 177 struct HdfDeviceObject *device; 178 struct RtcMethod *method; 179 void *data; 180 }; 181 ``` 182 183 - Instantiating **RtcMethod** in **RtcHost** (other members are initialized by **Init**) 184 185 ``` 186 // Example in rtc_hi35xx.c: instantiate the hook. 187 static struct RtcMethod g_method = { 188 .ReadTime = HiRtcReadTime, 189 .WriteTime = HiRtcWriteTime, 190 .ReadAlarm = HiReadAlarm, 191 .WriteAlarm = HiWriteAlarm, 192 .RegisterAlarmCallback = HiRegisterAlarmCallback, 193 .AlarmInterruptEnable = HiAlarmInterruptEnable, 194 .GetFreq = HiGetFreq, 195 .SetFreq = HiSetFreq, 196 .Reset = HiReset, 197 .ReadReg = HiReadReg, 198 .WriteReg = HiWriteReg, 199 }; 200 ``` 201 202 - **Bind** function 203 204 **Input parameter**: 205 206 **HdfDeviceObject**, an interface parameter exposed by the driver, contains the .hcs information. 207 208 **Return value**: 209 210 **HDF_STATUS** 211 212 The table below describes some status. For more information, see **HDF_STATUS** in the **/drivers/framework/include/utils/hdf_base.h** file. 213 214 **Table 2** Description of HDF_STATUS 215 216 | Status | Description | 217 | ---------------------- | -------------------------- | 218 | HDF_ERR_INVALID_OBJECT | Invalid controller object. | 219 | HDF_ERR_MALLOC_FAIL | Failed to allocate memory. | 220 | HDF_ERR_INVALID_PARAM | Invalid parameter. | 221 | HDF_ERR_IO | I/O error. | 222 | HDF_SUCCESS | Initialization successful. | 223 | HDF_FAILURE | Initialization failed. | 224 225 **Function description**: 226 227 Binds the **HdfDeviceObject** object and **RtcHost**. 228 229 ``` 230 static int32_t HiRtcBind(struct HdfDeviceObject *device) 231 { 232 struct RtcHost *host = NULL; 233 host = RtcHostCreate(device); // Allocate memory and attach the device host with the device. 234 // Prerequisite for conversion between HdfDeviceObject and RtcHost. 235 ... 236 device->service = &host->service; // Prerequisite for conversion between HdfDeviceObject and RtcHost. 237 // It helps implement a global host by calling RtcHostFromDevice. 238 return HDF_SUCCESS; 239 } 240 ``` 241 242 - **Init** function 243 244 **Input parameter**: 245 246 **HdfDeviceObject**, an interface parameter exposed by the driver, contains the .hcs information. 247 248 **Return value**: 249 250 **HDF_STATUS** 251 252 **Function description**: 253 254 Initializes the custom structure object and **RtcHost**. 255 256 ``` 257 static int32_t HiRtcInit(struct HdfDeviceObject *device) 258 { 259 struct RtcHost *host = NULL; 260 struct RtcConfigInfo *rtcInfo = NULL; 261 ... 262 host = RtcHostFromDevice(device);// Forcibly convert HdfDeviceObject to RtcHost. 263 rtcInfo = OsalMemCalloc(sizeof(*rtcInfo)); 264 ... 265 // HiRtcConfigData reads attributes from the device configuration tree and fills in supportAnaCtrl, supportLock, spiBaseAddr, regAddrLength and irq of RTCInfo. 266 // Provide parameters for HiRtcSwInit and HiRtcSwInit. When HiRtcSwInit and HiRtcSwInit fail to be executed internally, Release() can be called to release memory. 267 if (HiRtcConfigData(rtcInfo, device->property) != 0) { 268 ... 269 } 270 if (HiRtcSwInit(rtcInfo)! = 0) {// Address mapping and interrupt registration. 271 ... 272 } 273 if (HiRtcHwInit(rtcInfo)! = 0) {// Initialize ANACTRL and lockAddr. 274 ... 275 } 276 277 host->method = &g_method; // Attach the RtcMethod instance. 278 host->data = rtcInfo; // Prerequisites for conversion between RtcConfigInfo and RtcHost. 279 HDF_LOGI("Hdf dev service:%s init success!", HdfDeviceGetServiceName(device)); 280 return HDF_SUCCESS; 281 } 282 ``` 283 284 - **Release** function 285 286 **Input parameter**: 287 288 **HdfDeviceObject**, an interface parameter exposed by the driver, contains the .hcs information. 289 290 **Return value**: 291 292 No value is returned. 293 294 **Function description**: 295 296 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. 297 298 299 >  **NOTE**<br> 300 > 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. 301 302 303 ``` 304 static void HiRtcRelease(struct HdfDeviceObject *device) 305 { 306 struct RtcHost *host = NULL; 307 struct RtcConfigInfo *rtcInfo = NULL; 308 ... 309 host = RtcHostFromDevice(device); // Forcibly convert HdfDeviceObject to RtcHost. 310 rtcInfo = (struct RtcConfigInfo *)host->data;// Forcibly convert RtcHost to RtcConfigInfo. 311 if (rtcInfo != NULL) { 312 HiRtcSwExit(rtcInfo); 313 OsalMemFree(rtcInfo); // Release RtcConfigInfo. 314 host->data = NULL; 315 } 316 RtcHostDestroy(host); // Release RtcHost. 317 } 318 ``` 319
