版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/JerryGou/article/details/86660459
RX8025驱动-STM+Linux程序下载 ：https://download.csdn.net/download/jerrygou/10940406
Rx8025芯片手册+使用说明（英语+汉语）：https://download.csdn.net/download/jerrygou/10940411
一、Rx-8025T IIC-BUS接口实时时钟
二、I2C寄存器
三、I2C-0驱动
3.1、I2C-0的platform_device平台设备注册
//i2c-0的总线配置
static struct nuc970_platform_i2c nuc970_i2c0_data = {
.bus_num = 0,//这个参数很重要，决定i2c-0的总线为0，从设备通过0总线挂载到i2c-0适
//配器上，下面会提到从设备通过i2c_register_board_info()注册设备信息，
//其中该函数的第一个参数即为总线号，这样就将从设备与相应的i2c-0适配
//器连接上，从设备就可以使用该适配器的资源，对外挂I2C硬件设备进行操作。
.bus_freq = 100000,
};
//i2c-0的资源配置
static struct resource nuc970_i2c0_resource[] = {
[0] = {
.start = NUC970_PA_I2C0,
.end = NUC970_PA_I2C0 + NUC970_SZ_I2C0 - 1,
.flags = IORESOURCE_MEM,
},
[1] = {
.start = IRQ_I2C0,
.end = IRQ_I2C0,
.flags = IORESOURCE_IRQ,
}
};
//platform_device平台设备资源
struct platform_device nuc970_device_i2c0 = {
.name = "nuc970-i2c0",
.id = -1,
.num_resources = ARRAY_SIZE(nuc970_i2c0_resource),
.resource = nuc970_i2c0_resource,
.dev = {
.platform_data = &nuc970_i2c0_data,
}
};
static struct platform_device *nuc970_public_dev[] __initdata = {
&nuc970_device_i2c0,
}
//注册platform_device设备
platform_add_devices(nuc970_public_dev, ARRAY_SIZE(nuc970_public_dev));3.2、注册I2C从设备信息
//i2c-0下的从设备设备信息
static struct i2c_board_info __initdata nuc970_i2c_clients0[] =
{
{I2C_BOARD_INFO("rx8025", 0x32),},
};由于I2C发送数据时，首现发送的第一个字节是对外围从设备进行寻址，我们知道首字节的高4bit（bit7~4）是外围设备的厂商编码，bit3~1是外围设备的地址（具体地址由该芯片的外围电路决定），而bit0是对表示当前'读/写'操作，这里的0x50没有包括bit0‘读写’操作，所以这里的0x32只有7个bit，适配器在进行操作时会左移一位，0x32=00110010b -> 向左偏移1bit=0110 010x，高bit7~4为6恰好是Rx8025的厂商编码，bit3~1为2恰好是外围器件地址。
//注册i2c从设备信息
i2c_register_board_info(0, nuc970_i2c_clients0, sizeof(nuc970_i2c_clients0)/sizeof(struct i2c_board_info));
//0就是1.1中提到的bus_num的总线，通过该总线就将从设备与nuc970-i2c0适配器进行了连接3.3、I2C-0的platform-driver设备驱动注册
static struct platform_driver nuc970_i2c0_driver = {
.probe = nuc970_i2c0_probe,
.remove = nuc970_i2c0_remove,
.driver = {
.name = "nuc970-i2c0",
.owner = THIS_MODULE,
#if defined(CONFIG_OF)
.of_match_table = of_match_ptr(nuc970_i2c0_of_match),
#endif
.pm = NUC970_I2C0_PMOPS,
},
};
module_platform_driver(nuc970_i2c0_driver);四、RTC设备驱动
4.1、RTC设备驱动注册
static const struct i2c_device_id rx8025_id[] = {
{ "rx8025", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, rx8025_id);
static struct i2c_driver rx8025_driver = {
.driver = {
.name = "rtc-rx8025",
.owner = THIS_MODULE,
},
.probe = rx8025_probe,
.remove = rx8025_remove,
.id_table = rx8025_id,
};
module_i2c_driver(rx8025_driver);4.2、内核配置单配置
为了系统一上电就同步硬件RTC时钟，需修改配置单：
Device Drivers --->
<*> I2C support --->
--- I2C support
[*] Enable compatibility bits for old user-space
< > I2C device interface
< > I2C bus multiplexing support
[*] Autoselect pertinent helper modules
I2C Hardware Bus support --->
<*> GPIO-based bitbanging I2C
<*> NUC970/N9H30 I2C Driver for Port 0
[*] Real Time Clock --->
[*] Set system time from RTC on startup and resume //系统一上电就同步硬件RTC时钟
[*] Set the RTC time based on NTP synchronization
(rtc0) RTC used to set the system time
[*] RTC debug support
*** RTC interfaces ***
[*] /sys/class/rtc/rtcN (sysfs)
[*] /proc/driver/rtc (procfs for rtcN)
[*] /dev/rtcN (character devices)
[ ] RTC UIE emulation on dev interface
<*> Epson RX-8025SA/NB
< > NUC970/N9H30 RTC driver五、修正RTC驱动
六、测试
测试参考：kernel（十二）RTC
