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I2C子系统之驱动SSD1306 OLED

理解I2C设备驱动框架，主要围绕四个结构体去分析就容易了。

struct i2c_algorithm：提供I2C协议的实现的操作，如：master_xfer实现数据收发的最基本方法。

struct i2c_adapter：每一个i2c_adapter都代表一个I2C物理接口，一个cpu可以有多个I2C接口（i2c_adapter），i2c_algorithm就是为i2c_adapter提供I2C协议的实现。每增加一个i2c接口，即是向i2c_bus_type (i2c_core.c)注册一个i2c_adapter

struct i2c_driver：代表着一类I2C从机设备的驱动，比如：at24cxx的驱动，不同类型的I2C从机需要注册不同的i2c_driver，如：ssd1306的驱动不同于at24cxx的驱动。每增加一个类型的I2C从机设备，都要向i2c_bus_type (i2c_core.c)注册一个i2c_driver

struct i2c_client：代表具体的某一个I2C从机设备，如：at24cxx系列的设备，有at24c01，at24c02等，每增加一个at24cxx设备，都要注册一个i2c_client。只有I2C从机设备被探测到，i2c_client才会被注册。

这四者的关系可以分为：i2c_algorithm和i2c_adapter一起驱动I2C总线，i2c_driver和i2c_client一起实现设备驱动。

注：linux目前只支持I2C主机模式。本文引用内核源码中i2c-algo-bit.c和i2c-gpio.c文件来讲解， i2c_driver由驱动开发者根据特定的设备提供，这里引用作者提供的ssd1306.c。i2c-algo-bit.c和i2c-gpio.c共同实现IO模拟I2C。

i2c-algo-bit.c提供了一个i2c_algorithm，i2c-gpio.c提供了一个i2c_adapter。

i2c-algo-bit.c通过以下代码绑定到i2c-gpio.c

i2c-algo-bit.c

 1 static const struct i2c_algorithm i2c_bit_algo = {
 2     .master_xfer    = bit_xfer,
 3     .functionality  = bit_func,
 4 };
 5 
 6 static int i2c_bit_prepare_bus(struct i2c_adapter *adap)
 7 {
 8     ... ...
 9     adap->algo = &i2c_bit_algo;
10     ... ...
11     return 0;
12 }
13 
14 int i2c_bit_add_bus(struct i2c_adapter *adap)
15 {
16     ... ...
17     err = i2c_bit_prepare_bus(adap);
18     ... ...
19     return i2c_add_adapter(adap);
20 }

i2c-gpio.c

 1 static int __init i2c_gpio_probe(struct platform_device *pdev)
 2 {
 3     struct i2c_gpio_platform_data *pdata;
 4     struct i2c_algo_bit_data *bit_data;
 5     struct i2c_adapter *adap;
 6     ... ...
 7     pdata = pdev->dev.platform_data;
 8     ... ...
 9     i2c_bit_add_bus(adap);
10     ... ...
11 }

这里就注册了一个i2c_adapter。

要驱动ssd1306，因此对应地要提供一个i2c_driver，与i2c_adapter建立关系。

ssd1306.c

 1 static struct i2c_driver ssd1306_driver = {
 2     .driver = {
 3             .name   = "ssd1306",
 4         },
 5         .id     = I2C_DRIVERID_I2CDEV,
 6         .attach_adapter = ssd1306_attach_adapter,
 7         .detach_client  = ssd1306_detach_client,
 8 };
 9 
10 static int ssd1306_module_init(void)
11 {
12     i2c_add_driver(&ssd1306_driver);
13     return 0;
14 }

i2c_driver和i2c_adapter是怎样建立关系的呢？

i2c_bus_type (i2c_core.c)负责桥接i2c_driver和i2c_adapter建立关系，在i2c_driver和i2c_adapter注册的时候，两者都会调用driver->attach_adapter(adapter)

 1 int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
 2 {
 3     ... ...
 4     driver->attach_adapter(adapter);
 5     ... ...
 6     return 0;
 7 }
 8 
 9 static int i2c_register_adapter(struct i2c_adapter *adap)
10 {
11     ... ...
12     driver->attach_adapter(adap);
13     ... ...
14 }

driver->attach_adapter(adapter)实际上调用

1 static int ssd1306_attach_adapter(struct i2c_adapter *adapter)
2 {
3     return i2c_probe(adapter, &addr_data, ssd1306_detect);
4 }

I2c_probe()函数的作用就是，探测是否存在ssd1306这个设备，是怎样探测的呢？就是通过发送从机地址到ssd1306，如果ssd1306返回应答信号，就认为探测到了。

 1 int i2c_probe(struct i2c_adapter *adapter,
 2           struct i2c_client_address_data *address_data,
 3           int (*found_proc) (struct i2c_adapter *, int, int))
 4 {
 5     ... ...
 6     i2c_probe_address(adapter,
 7                     address_data->probe[i + 1],
 8                     -1, found_proc);
 9     ... ...
10 }

代码太多，简化函数调用关系如下：

1 i2c_probe_address()
2     i2c_smbus_xfer()
3         i2c_smbus_xfer_emulated();
4             i2c_transfer();
5                 adap->algo->master_xfer(adap,msgs,num);

adap->algo->master_xfer(adap,msgs,num);实际调用的是bit_xfer()

探测到ssd1306后，其实也就说明了探测到的I2C地址有效，还需要注册一个描述SSD1306的i2c_client。

 1 static int ssd1306_detect(struct i2c_adapter *adapter, int address, int kind)
 2 {   
 3     printk("ssd1306_detect
");
 4 
 5     ssd1306_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
 6     ssd1306_client->addr    = address;
 7     ssd1306_client->adapter = adapter;
 8     ssd1306_client->driver  = &ssd1306_driver;
 9     strcpy(ssd1306_client->name, "ssd1306");
10     
11     i2c_attach_client(ssd1306_client);
12     
13     ... ...
14 }

先转下话题。

在i2c-gpio.c中，

1 static int __init i2c_gpio_init(void)
2 {
3     ... ...
4     ret = platform_driver_probe(&i2c_gpio_driver, i2c_gpio_probe);
5     ... ...
6 }

这里实际上是注册了一个platform_driver，我们还要对应的为他注册一个platform_device，

这个platform_device提供了硬件相关的设置，如指定那两个io口为SCL和SDA。

I2c_gpio_dev.c中

 1 static struct i2c_gpio_platform_data i2c_dev = {
 2     .sda_pin = S3C2410_GPG6,
 3     .scl_pin = S3C2410_GPG5,
 4     .udelay = 0,
 5     .timeout = 0,
 6     .sda_is_open_drain = 1,
 7     .scl_is_open_drain = 1,
 8     .scl_is_output_only = 1
 9 };
10 
11 static struct platform_device i2c_platform_dev = {
12     .name         = "i2c-gpio",
13     .id           = -1,
14     .dev = { 
15         .release = i2c_dev_release,
16         .platform_data = (void *)&i2c_dev,
17     },
18 };
19 
20 static int i2c_dev_init(void)
21 {
22     platform_device_register(&i2c_platform_dev);
23     return 0;
24 }

如果platform_device和platform_driver匹配，就会调用i2c_gpio_probe()

 1 static int __init i2c_gpio_probe(struct platform_device *pdev)
 2 {
 3     struct i2c_gpio_platform_data *pdata;
 4     struct i2c_algo_bit_data *bit_data;
 5     struct i2c_adapter *adap;
 6     ... ...
 7     pdata = pdev->dev.platform_data;
 8     ... ...
 9     i2c_bit_add_bus(adap);
10     ... ...
11 }

只有platform_device和platform_driver匹配才能注册i2c_adapter。

到这里，就可以操作ssd1306了。ssd1306写一个字节的操作：

 1 static void ssd1306_write_byte(uint8_t chData, uint8_t chCmd) 
 2 {
 3     uint8_t cmd = 0x00;
 4     
 5     if (chCmd) {
 6         cmd = 0x40;
 7     } else {
 8         cmd = 0x00;
 9     }
10 
11     i2c_smbus_write_byte_data(ssd1306_client, cmd, chData);
12 }

实际上调用了i2c_smbus_write_byte_data()

I2c_core.c提供了几个I2C的读写函数：

1 s32 i2c_smbus_write_byte_data(struct i2c_client *client, u8 command, u8 value);
2 s32 i2c_smbus_read_word_data(struct i2c_client *client, u8 command);
3 ... ...
4 s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client, u8 command, u8 *values);
5 s32 i2c_smbus_write_i2c_block_data(struct i2c_client *client, u8 command,
6                    u8 length, const u8 *values)

运行代码

注：由于源码的i2c-gpio-bit.c只支持具有开漏输入输出功能的IO模拟I2C，而我的开发板已经没有具有开漏输入输出功能的IO了，只能使用普通的上啦输入输出IO，对SDA的读写操作，需要切换输入输出方向。因此我把i2c-gpio-bit.c改成普通IO操作SDA，命名为my-i2c-gpio-bit.c，同时i2c-gpio-bit.h和i2c-gpio.c也要做相应改动，分别改为my-i2c-gpio-bit.h和my-i2c-gpio.c。如果使用具有开漏输入输出功能的IO，可以直接使用i2c-gpio-bit.c，i2c-gpio-bit.h，i2c-gpio.c。

代码

i2c_gpio_dev.c

 1 #include <linux/module.h>
 2 #include <linux/version.h>
 3 
 4 #include <linux/init.h>
 5 
 6 #include <linux/kernel.h>
 7 #include <linux/types.h>
 8 #include <linux/interrupt.h>
 9 #include <linux/list.h>
10 #include <linux/timer.h>
11 #include <linux/init.h>
12 #include <linux/serial_core.h>
13 #include <linux/platform_device.h>
14 #include <linux/gpio_keys.h>
15 #include <linux/input.h>
16 #include <linux/irq.h>
17 #include <linux/i2c-gpio.h>
18 
19 #include <asm/gpio.h>
20 #include <asm/io.h>
21 #include <asm/arch/regs-gpio.h>
22 
23 
24 /* [cgw]:  */
25 
26 static struct i2c_gpio_platform_data i2c_dev = {
27     .sda_pin = S3C2410_GPG6,
28     .scl_pin = S3C2410_GPG5,
29     .udelay = 0,
30     .timeout = 0,
31     .sda_is_open_drain = 1,
32     .scl_is_open_drain = 1,
33     .scl_is_output_only = 1
34 };
35 
36 static void i2c_dev_release(struct device * dev)
37 {
38     printk("i2c_dev_release! 
");
39 }
40 
41 /* [cgw]: 分配一个平台设备 */
42 static struct platform_device i2c_platform_dev = {
43     .name         = "i2c-gpio",
44     .id           = -1,
45     .dev = { 
46         .release = i2c_dev_release,
47         .platform_data = (void *)&i2c_dev,
48     },
49 };
50 
51 
52 static int i2c_dev_init(void)
53 {
54     /* [cgw]: 注册i2c_platform_dev平台设备 */
55     platform_device_register(&i2c_platform_dev);
56     return 0;
57 }
58 
59 static void i2c_dev_exit(void)
60 {
61     /* [cgw]: 注销i2c_platform_dev平台设备 */
62     platform_device_unregister(&i2c_platform_dev);
63 }
64 
65 module_init(i2c_dev_init);
66 module_exit(i2c_dev_exit);
67 
68 MODULE_LICENSE("GPL");

ssd1306.c

  1 #include <linux/kernel.h>
  2 #include <linux/init.h>
  3 #include <linux/module.h>
  4 #include <linux/slab.h>
  5 #include <linux/jiffies.h>
  6 #include <linux/i2c.h>
  7 #include <linux/mutex.h>
  8 #include <linux/fs.h>
  9 #include <asm/uaccess.h>
 10 
 11 
 12 #define SSD1306_CMD    0
 13 #define SSD1306_DAT    1
 14 
 15 #define SSD1306_WIDTH    128
 16 #define SSD1306_HEIGHT   64
 17 
 18 static uint8_t s_chDispalyBuffer[128][8];
 19 
 20 const uint8_t c_chFont1608[95][16] = {      
 21 {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*" ",0*/
 22 {0x00,0x00,0x00,0x00,0x00,0x00,0x1F,0xCC,0x00,0x0C,0x00,0x00,0x00,0x00,0x00,0x00},/*"!",1*/
 23 {0x00,0x00,0x08,0x00,0x30,0x00,0x60,0x00,0x08,0x00,0x30,0x00,0x60,0x00,0x00,0x00},/*""",2*/
 24 {0x02,0x20,0x03,0xFC,0x1E,0x20,0x02,0x20,0x03,0xFC,0x1E,0x20,0x02,0x20,0x00,0x00},/*"#",3*/
 25 {0x00,0x00,0x0E,0x18,0x11,0x04,0x3F,0xFF,0x10,0x84,0x0C,0x78,0x00,0x00,0x00,0x00},/*"$",4*/
 26 {0x0F,0x00,0x10,0x84,0x0F,0x38,0x00,0xC0,0x07,0x78,0x18,0x84,0x00,0x78,0x00,0x00},/*"%",5*/
 27 {0x00,0x78,0x0F,0x84,0x10,0xC4,0x11,0x24,0x0E,0x98,0x00,0xE4,0x00,0x84,0x00,0x08},/*"&",6*/
 28 {0x08,0x00,0x68,0x00,0x70,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*"'",7*/
 29 {0x00,0x00,0x00,0x00,0x00,0x00,0x07,0xE0,0x18,0x18,0x20,0x04,0x40,0x02,0x00,0x00},/*"(",8*/
 30 {0x00,0x00,0x40,0x02,0x20,0x04,0x18,0x18,0x07,0xE0,0x00,0x00,0x00,0x00,0x00,0x00},/*")",9*/
 31 {0x02,0x40,0x02,0x40,0x01,0x80,0x0F,0xF0,0x01,0x80,0x02,0x40,0x02,0x40,0x00,0x00},/*"*",10*/
 32 {0x00,0x80,0x00,0x80,0x00,0x80,0x0F,0xF8,0x00,0x80,0x00,0x80,0x00,0x80,0x00,0x00},/*"+",11*/
 33 {0x00,0x01,0x00,0x0D,0x00,0x0E,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*",",12*/
 34 {0x00,0x00,0x00,0x80,0x00,0x80,0x00,0x80,0x00,0x80,0x00,0x80,0x00,0x80,0x00,0x80},/*"-",13*/
 35 {0x00,0x00,0x00,0x0C,0x00,0x0C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*".",14*/
 36 {0x00,0x00,0x00,0x06,0x00,0x18,0x00,0x60,0x01,0x80,0x06,0x00,0x18,0x00,0x20,0x00},/*"/",15*/
 37 {0x00,0x00,0x07,0xF0,0x08,0x08,0x10,0x04,0x10,0x04,0x08,0x08,0x07,0xF0,0x00,0x00},/*"0",16*/
 38 {0x00,0x00,0x08,0x04,0x08,0x04,0x1F,0xFC,0x00,0x04,0x00,0x04,0x00,0x00,0x00,0x00},/*"1",17*/
 39 {0x00,0x00,0x0E,0x0C,0x10,0x14,0x10,0x24,0x10,0x44,0x11,0x84,0x0E,0x0C,0x00,0x00},/*"2",18*/
 40 {0x00,0x00,0x0C,0x18,0x10,0x04,0x11,0x04,0x11,0x04,0x12,0x88,0x0C,0x70,0x00,0x00},/*"3",19*/
 41 {0x00,0x00,0x00,0xE0,0x03,0x20,0x04,0x24,0x08,0x24,0x1F,0xFC,0x00,0x24,0x00,0x00},/*"4",20*/
 42 {0x00,0x00,0x1F,0x98,0x10,0x84,0x11,0x04,0x11,0x04,0x10,0x88,0x10,0x70,0x00,0x00},/*"5",21*/
 43 {0x00,0x00,0x07,0xF0,0x08,0x88,0x11,0x04,0x11,0x04,0x18,0x88,0x00,0x70,0x00,0x00},/*"6",22*/
 44 {0x00,0x00,0x1C,0x00,0x10,0x00,0x10,0xFC,0x13,0x00,0x1C,0x00,0x10,0x00,0x00,0x00},/*"7",23*/
 45 {0x00,0x00,0x0E,0x38,0x11,0x44,0x10,0x84,0x10,0x84,0x11,0x44,0x0E,0x38,0x00,0x00},/*"8",24*/
 46 {0x00,0x00,0x07,0x00,0x08,0x8C,0x10,0x44,0x10,0x44,0x08,0x88,0x07,0xF0,0x00,0x00},/*"9",25*/
 47 {0x00,0x00,0x00,0x00,0x00,0x00,0x03,0x0C,0x03,0x0C,0x00,0x00,0x00,0x00,0x00,0x00},/*":",26*/
 48 {0x00,0x00,0x00,0x00,0x00,0x01,0x01,0x06,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*";",27*/
 49 {0x00,0x00,0x00,0x80,0x01,0x40,0x02,0x20,0x04,0x10,0x08,0x08,0x10,0x04,0x00,0x00},/*"<",28*/
 50 {0x02,0x20,0x02,0x20,0x02,0x20,0x02,0x20,0x02,0x20,0x02,0x20,0x02,0x20,0x00,0x00},/*"=",29*/
 51 {0x00,0x00,0x10,0x04,0x08,0x08,0x04,0x10,0x02,0x20,0x01,0x40,0x00,0x80,0x00,0x00},/*">",30*/
 52 {0x00,0x00,0x0E,0x00,0x12,0x00,0x10,0x0C,0x10,0x6C,0x10,0x80,0x0F,0x00,0x00,0x00},/*"?",31*/
 53 {0x03,0xE0,0x0C,0x18,0x13,0xE4,0x14,0x24,0x17,0xC4,0x08,0x28,0x07,0xD0,0x00,0x00},/*"@",32*/
 54 {0x00,0x04,0x00,0x3C,0x03,0xC4,0x1C,0x40,0x07,0x40,0x00,0xE4,0x00,0x1C,0x00,0x04},/*"A",33*/
 55 {0x10,0x04,0x1F,0xFC,0x11,0x04,0x11,0x04,0x11,0x04,0x0E,0x88,0x00,0x70,0x00,0x00},/*"B",34*/
 56 {0x03,0xE0,0x0C,0x18,0x10,0x04,0x10,0x04,0x10,0x04,0x10,0x08,0x1C,0x10,0x00,0x00},/*"C",35*/
 57 {0x10,0x04,0x1F,0xFC,0x10,0x04,0x10,0x04,0x10,0x04,0x08,0x08,0x07,0xF0,0x00,0x00},/*"D",36*/
 58 {0x10,0x04,0x1F,0xFC,0x11,0x04,0x11,0x04,0x17,0xC4,0x10,0x04,0x08,0x18,0x00,0x00},/*"E",37*/
 59 {0x10,0x04,0x1F,0xFC,0x11,0x04,0x11,0x00,0x17,0xC0,0x10,0x00,0x08,0x00,0x00,0x00},/*"F",38*/
 60 {0x03,0xE0,0x0C,0x18,0x10,0x04,0x10,0x04,0x10,0x44,0x1C,0x78,0x00,0x40,0x00,0x00},/*"G",39*/
 61 {0x10,0x04,0x1F,0xFC,0x10,0x84,0x00,0x80,0x00,0x80,0x10,0x84,0x1F,0xFC,0x10,0x04},/*"H",40*/
 62 {0x00,0x00,0x10,0x04,0x10,0x04,0x1F,0xFC,0x10,0x04,0x10,0x04,0x00,0x00,0x00,0x00},/*"I",41*/
 63 {0x00,0x03,0x00,0x01,0x10,0x01,0x10,0x01,0x1F,0xFE,0x10,0x00,0x10,0x00,0x00,0x00},/*"J",42*/
 64 {0x10,0x04,0x1F,0xFC,0x11,0x04,0x03,0x80,0x14,0x64,0x18,0x1C,0x10,0x04,0x00,0x00},/*"K",43*/
 65 {0x10,0x04,0x1F,0xFC,0x10,0x04,0x00,0x04,0x00,0x04,0x00,0x04,0x00,0x0C,0x00,0x00},/*"L",44*/
 66 {0x10,0x04,0x1F,0xFC,0x1F,0x00,0x00,0xFC,0x1F,0x00,0x1F,0xFC,0x10,0x04,0x00,0x00},/*"M",45*/
 67 {0x10,0x04,0x1F,0xFC,0x0C,0x04,0x03,0x00,0x00,0xE0,0x10,0x18,0x1F,0xFC,0x10,0x00},/*"N",46*/
 68 {0x07,0xF0,0x08,0x08,0x10,0x04,0x10,0x04,0x10,0x04,0x08,0x08,0x07,0xF0,0x00,0x00},/*"O",47*/
 69 {0x10,0x04,0x1F,0xFC,0x10,0x84,0x10,0x80,0x10,0x80,0x10,0x80,0x0F,0x00,0x00,0x00},/*"P",48*/
 70 {0x07,0xF0,0x08,0x18,0x10,0x24,0x10,0x24,0x10,0x1C,0x08,0x0A,0x07,0xF2,0x00,0x00},/*"Q",49*/
 71 {0x10,0x04,0x1F,0xFC,0x11,0x04,0x11,0x00,0x11,0xC0,0x11,0x30,0x0E,0x0C,0x00,0x04},/*"R",50*/
 72 {0x00,0x00,0x0E,0x1C,0x11,0x04,0x10,0x84,0x10,0x84,0x10,0x44,0x1C,0x38,0x00,0x00},/*"S",51*/
 73 {0x18,0x00,0x10,0x00,0x10,0x04,0x1F,0xFC,0x10,0x04,0x10,0x00,0x18,0x00,0x00,0x00},/*"T",52*/
 74 {0x10,0x00,0x1F,0xF8,0x10,0x04,0x00,0x04,0x00,0x04,0x10,0x04,0x1F,0xF8,0x10,0x00},/*"U",53*/
 75 {0x10,0x00,0x1E,0x00,0x11,0xE0,0x00,0x1C,0x00,0x70,0x13,0x80,0x1C,0x00,0x10,0x00},/*"V",54*/
 76 {0x1F,0xC0,0x10,0x3C,0x00,0xE0,0x1F,0x00,0x00,0xE0,0x10,0x3C,0x1F,0xC0,0x00,0x00},/*"W",55*/
 77 {0x10,0x04,0x18,0x0C,0x16,0x34,0x01,0xC0,0x01,0xC0,0x16,0x34,0x18,0x0C,0x10,0x04},/*"X",56*/
 78 {0x10,0x00,0x1C,0x00,0x13,0x04,0x00,0xFC,0x13,0x04,0x1C,0x00,0x10,0x00,0x00,0x00},/*"Y",57*/
 79 {0x08,0x04,0x10,0x1C,0x10,0x64,0x10,0x84,0x13,0x04,0x1C,0x04,0x10,0x18,0x00,0x00},/*"Z",58*/
 80 {0x00,0x00,0x00,0x00,0x00,0x00,0x7F,0xFE,0x40,0x02,0x40,0x02,0x40,0x02,0x00,0x00},/*"[",59*/
 81 {0x00,0x00,0x30,0x00,0x0C,0x00,0x03,0x80,0x00,0x60,0x00,0x1C,0x00,0x03,0x00,0x00},/*"",60*/
 82 {0x00,0x00,0x40,0x02,0x40,0x02,0x40,0x02,0x7F,0xFE,0x00,0x00,0x00,0x00,0x00,0x00},/*"]",61*/
 83 {0x00,0x00,0x00,0x00,0x20,0x00,0x40,0x00,0x40,0x00,0x40,0x00,0x20,0x00,0x00,0x00},/*"^",62*/
 84 {0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01},/*"_",63*/
 85 {0x00,0x00,0x40,0x00,0x40,0x00,0x20,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*"`",64*/
 86 {0x00,0x00,0x00,0x98,0x01,0x24,0x01,0x44,0x01,0x44,0x01,0x44,0x00,0xFC,0x00,0x04},/*"a",65*/
 87 {0x10,0x00,0x1F,0xFC,0x00,0x88,0x01,0x04,0x01,0x04,0x00,0x88,0x00,0x70,0x00,0x00},/*"b",66*/
 88 {0x00,0x00,0x00,0x70,0x00,0x88,0x01,0x04,0x01,0x04,0x01,0x04,0x00,0x88,0x00,0x00},/*"c",67*/
 89 {0x00,0x00,0x00,0x70,0x00,0x88,0x01,0x04,0x01,0x04,0x11,0x08,0x1F,0xFC,0x00,0x04},/*"d",68*/
 90 {0x00,0x00,0x00,0xF8,0x01,0x44,0x01,0x44,0x01,0x44,0x01,0x44,0x00,0xC8,0x00,0x00},/*"e",69*/
 91 {0x00,0x00,0x01,0x04,0x01,0x04,0x0F,0xFC,0x11,0x04,0x11,0x04,0x11,0x00,0x18,0x00},/*"f",70*/
 92 {0x00,0x00,0x00,0xD6,0x01,0x29,0x01,0x29,0x01,0x29,0x01,0xC9,0x01,0x06,0x00,0x00},/*"g",71*/
 93 {0x10,0x04,0x1F,0xFC,0x00,0x84,0x01,0x00,0x01,0x00,0x01,0x04,0x00,0xFC,0x00,0x04},/*"h",72*/
 94 {0x00,0x00,0x01,0x04,0x19,0x04,0x19,0xFC,0x00,0x04,0x00,0x04,0x00,0x00,0x00,0x00},/*"i",73*/
 95 {0x00,0x00,0x00,0x03,0x00,0x01,0x01,0x01,0x19,0x01,0x19,0xFE,0x00,0x00,0x00,0x00},/*"j",74*/
 96 {0x10,0x04,0x1F,0xFC,0x00,0x24,0x00,0x40,0x01,0xB4,0x01,0x0C,0x01,0x04,0x00,0x00},/*"k",75*/
 97 {0x00,0x00,0x10,0x04,0x10,0x04,0x1F,0xFC,0x00,0x04,0x00,0x04,0x00,0x00,0x00,0x00},/*"l",76*/
 98 {0x01,0x04,0x01,0xFC,0x01,0x04,0x01,0x00,0x01,0xFC,0x01,0x04,0x01,0x00,0x00,0xFC},/*"m",77*/
 99 {0x01,0x04,0x01,0xFC,0x00,0x84,0x01,0x00,0x01,0x00,0x01,0x04,0x00,0xFC,0x00,0x04},/*"n",78*/
100 {0x00,0x00,0x00,0xF8,0x01,0x04,0x01,0x04,0x01,0x04,0x01,0x04,0x00,0xF8,0x00,0x00},/*"o",79*/
101 {0x01,0x01,0x01,0xFF,0x00,0x85,0x01,0x04,0x01,0x04,0x00,0x88,0x00,0x70,0x00,0x00},/*"p",80*/
102 {0x00,0x00,0x00,0x70,0x00,0x88,0x01,0x04,0x01,0x04,0x01,0x05,0x01,0xFF,0x00,0x01},/*"q",81*/
103 {0x01,0x04,0x01,0x04,0x01,0xFC,0x00,0x84,0x01,0x04,0x01,0x00,0x01,0x80,0x00,0x00},/*"r",82*/
104 {0x00,0x00,0x00,0xCC,0x01,0x24,0x01,0x24,0x01,0x24,0x01,0x24,0x01,0x98,0x00,0x00},/*"s",83*/
105 {0x00,0x00,0x01,0x00,0x01,0x00,0x07,0xF8,0x01,0x04,0x01,0x04,0x00,0x00,0x00,0x00},/*"t",84*/
106 {0x01,0x00,0x01,0xF8,0x00,0x04,0x00,0x04,0x00,0x04,0x01,0x08,0x01,0xFC,0x00,0x04},/*"u",85*/
107 {0x01,0x00,0x01,0x80,0x01,0x70,0x00,0x0C,0x00,0x10,0x01,0x60,0x01,0x80,0x01,0x00},/*"v",86*/
108 {0x01,0xF0,0x01,0x0C,0x00,0x30,0x01,0xC0,0x00,0x30,0x01,0x0C,0x01,0xF0,0x01,0x00},/*"w",87*/
109 {0x00,0x00,0x01,0x04,0x01,0x8C,0x00,0x74,0x01,0x70,0x01,0x8C,0x01,0x04,0x00,0x00},/*"x",88*/
110 {0x01,0x01,0x01,0x81,0x01,0x71,0x00,0x0E,0x00,0x18,0x01,0x60,0x01,0x80,0x01,0x00},/*"y",89*/
111 {0x00,0x00,0x01,0x84,0x01,0x0C,0x01,0x34,0x01,0x44,0x01,0x84,0x01,0x0C,0x00,0x00},/*"z",90*/
112 {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x00,0x3E,0xFC,0x40,0x02,0x40,0x02},/*"{",91*/
113 {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xFF,0xFF,0x00,0x00,0x00,0x00,0x00,0x00},/*"|",92*/
114 {0x00,0x00,0x40,0x02,0x40,0x02,0x3E,0xFC,0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*"}",93*/
115 {0x00,0x00,0x60,0x00,0x80,0x00,0x80,0x00,0x40,0x00,0x40,0x00,0x20,0x00,0x20,0x00},/*"~",94*/
116 };
117 
118 static unsigned short normal_i2c[] = { 0x3C, I2C_CLIENT_END };
119 I2C_CLIENT_INSMOD_1(ssd1306);
120 
121 
122 static int ssd1306_attach_adapter(struct i2c_adapter *adapter);
123 static int ssd1306_detach_client(struct i2c_client *client);
124 
125 
126 static struct i2c_driver ssd1306_driver = {
127     .driver = {
128             .name    = "ssd1306",
129         },
130         .id     = I2C_DRIVERID_I2CDEV,
131         .attach_adapter = ssd1306_attach_adapter,
132         .detach_client    = ssd1306_detach_client,
133 };
134 
135 struct i2c_client *ssd1306_client;
136 
137 static void ssd1306_write_byte(uint8_t chData, uint8_t chCmd) 
138 {
139     uint8_t cmd = 0x00;
140     
141     if (chCmd) {
142         cmd = 0x40;
143     } else {
144         cmd = 0x00;
145     }
146 
147     i2c_smbus_write_byte_data(ssd1306_client, cmd, chData);
148 }
149 
150 void ssd1306_display_on(void)
151 {
152     ssd1306_write_byte(0x8D, SSD1306_CMD);  
153     ssd1306_write_byte(0x14, SSD1306_CMD);  
154     ssd1306_write_byte(0xAF, SSD1306_CMD);  
155 }
156    
157 /**
158   * @brief  OLED turns off
159   *         
160   * @param  None
161   *         
162   * @retval  None
163 **/
164 void ssd1306_display_off(void)
165 {
166     ssd1306_write_byte(0x8D, SSD1306_CMD);  
167     ssd1306_write_byte(0x10, SSD1306_CMD); 
168     ssd1306_write_byte(0xAE, SSD1306_CMD);  
169 }
170 
171 void ssd1306_refresh_gram(void)
172 {
173     uint8_t i, j;
174     
175     for (i = 0; i < 8; i ++) {  
176         ssd1306_write_byte(0xB0 + i, SSD1306_CMD);    
177         ssd1306_write_byte(0x02, SSD1306_CMD); 
178         ssd1306_write_byte(0x10, SSD1306_CMD);     
179         for (j = 0; j < 128; j ++) {
180             ssd1306_write_byte(s_chDispalyBuffer[j][i], SSD1306_DAT); 
181         }
182     }   
183 }
184 
185 
186 void ssd1306_clear_screen(uint8_t chFill)  
187 { 
188     memset(s_chDispalyBuffer,chFill, sizeof(s_chDispalyBuffer));
189     ssd1306_refresh_gram();
190 }
191 
192 /**
193   * @brief  Draws a piont on the screen
194   *         
195   * @param  chXpos: Specifies the X position
196   * @param  chYpos: Specifies the Y position
197   * @param  chPoint: 0: the point turns off    1: the piont turns on 
198   *         
199   * @retval None
200 **/
201 
202 void ssd1306_draw_point(uint8_t chXpos, uint8_t chYpos, uint8_t chPoint)
203 {
204     uint8_t chPos, chBx, chTemp = 0;
205     
206     if (chXpos > 127 || chYpos > 63) {
207         return;
208     }
209     chPos = 7 - chYpos / 8; // 
210     chBx = chYpos % 8;
211     chTemp = 1 << (7 - chBx);
212     
213     if (chPoint) {
214         s_chDispalyBuffer[chXpos][chPos] |= chTemp;
215         
216     } else {
217         s_chDispalyBuffer[chXpos][chPos] &= ~chTemp;
218     }
219 }
220       
221 /**
222   * @brief  Fills a rectangle
223   *         
224   * @param  chXpos1: Specifies the X position 1 (X top left position)
225   * @param  chYpos1: Specifies the Y position 1 (Y top left position)
226   * @param  chXpos2: Specifies the X position 2 (X bottom right position)
227   * @param  chYpos3: Specifies the Y position 2 (Y bottom right position)
228   *         
229   * @retval 
230 **/
231 
232 void ssd1306_fill_screen(uint8_t chXpos1, uint8_t chYpos1, uint8_t chXpos2, uint8_t chYpos2, uint8_t chDot)  
233 {  
234     uint8_t chXpos, chYpos; 
235     
236     for (chXpos = chXpos1; chXpos <= chXpos2; chXpos ++) {
237         for (chYpos = chYpos1; chYpos <= chYpos2; chYpos ++) {
238             ssd1306_draw_point(chXpos, chYpos, chDot);
239         }
240     }    
241     
242     ssd1306_refresh_gram();
243 }
244 
245 
246 /**
247   * @brief Displays one character at the specified position    
248   *         
249   * @param  chXpos: Specifies the X position
250   * @param  chYpos: Specifies the Y position
251   * @param  chSize: 
252   * @param  chMode
253   * @retval 
254 **/
255 void ssd1306_display_char(uint8_t chXpos, uint8_t chYpos, uint8_t chChr, uint8_t chSize, uint8_t chMode)
256 {          
257     uint8_t i, j;
258     uint8_t chTemp, chYpos0 = chYpos;
259     
260     chChr = chChr - ' ';                   
261     for (i = 0; i < chSize; i ++) {   
262         if (chMode) {
263             chTemp = c_chFont1608[chChr][i];
264         } else {
265             chTemp = ~c_chFont1608[chChr][i];
266         }
267         
268         for (j = 0; j < 8; j ++) {
269             if (chTemp & 0x80) {
270                 ssd1306_draw_point(chXpos, chYpos, 1);
271             } else {
272                 ssd1306_draw_point(chXpos, chYpos, 0);
273             }
274             chTemp <<= 1;
275             chYpos ++;
276             
277             if ((chYpos - chYpos0) == chSize) {
278                 chYpos = chYpos0;
279                 chXpos ++;
280                 break;
281             }
282         }       
283     } 
284 }    
285 
286 /**
287   * @brief  Displays a string on the screen
288   *         
289   * @param  chXpos: Specifies the X position
290   * @param  chYpos: Specifies the Y position
291   * @param  pchString: Pointer to a string to display on the screen 
292   *         
293   * @retval  None
294 **/
295 void ssd1306_display_string(uint8_t chXpos, uint8_t chYpos, const uint8_t *pchString, uint8_t chSize, uint8_t chMode)
296 {
297     while (*pchString != '') {       
298         if (chXpos > (SSD1306_WIDTH - chSize / 2)) {
299             chXpos = 0;
300             chYpos += chSize;
301             if (chYpos > (SSD1306_HEIGHT - chSize)) {
302                 chYpos = chXpos = 0;
303                 ssd1306_clear_screen(0x00);
304             }
305         }
306         
307         ssd1306_display_char(chXpos, chYpos, *pchString, chSize, chMode);
308         chXpos += chSize / 2;
309         pchString ++;
310     }
311 }
312 
313 
314 void ssd1306_init(void)
315 {
316     ssd1306_write_byte(0xAE, SSD1306_CMD);//--turn off oled panel
317     ssd1306_write_byte(0x00, SSD1306_CMD);//---set low column address
318     ssd1306_write_byte(0x10, SSD1306_CMD);//---set high column address
319     ssd1306_write_byte(0x40, SSD1306_CMD);//--set start line address  Set Mapping RAM Display Start Line (0x00~0x3F)
320     ssd1306_write_byte(0x81, SSD1306_CMD);//--set contrast control register
321     ssd1306_write_byte(0xCF, SSD1306_CMD);// Set SEG Output Current Brightness
322     ssd1306_write_byte(0xA1, SSD1306_CMD);//--Set SEG/Column Mapping     
323     ssd1306_write_byte(0xC0, SSD1306_CMD);//Set COM/Row Scan Direction   
324     ssd1306_write_byte(0xA6, SSD1306_CMD);//--set normal display
325     ssd1306_write_byte(0xA8, SSD1306_CMD);//--set multiplex ratio(1 to 64)
326     ssd1306_write_byte(0x3f, SSD1306_CMD);//--1/64 duty
327     ssd1306_write_byte(0xD3, SSD1306_CMD);//-set display offset    Shift Mapping RAM Counter (0x00~0x3F)
328     ssd1306_write_byte(0x00, SSD1306_CMD);//-not offset
329     ssd1306_write_byte(0xd5, SSD1306_CMD);//--set display clock divide ratio/oscillator frequency
330     ssd1306_write_byte(0x80, SSD1306_CMD);//--set divide ratio, Set Clock as 100 Frames/Sec
331     ssd1306_write_byte(0xD9, SSD1306_CMD);//--set pre-charge period
332     ssd1306_write_byte(0xF1, SSD1306_CMD);//Set Pre-Charge as 15 Clocks & Discharge as 1 Clock
333     ssd1306_write_byte(0xDA, SSD1306_CMD);//--set com pins hardware configuration
334     ssd1306_write_byte(0x12, SSD1306_CMD);
335     ssd1306_write_byte(0xDB, SSD1306_CMD);//--set vcomh
336     ssd1306_write_byte(0x40, SSD1306_CMD);//Set VCOM Deselect Level
337     ssd1306_write_byte(0x20, SSD1306_CMD);//-Set Page Addressing Mode (0x00/0x01/0x02)
338     ssd1306_write_byte(0x02, SSD1306_CMD);//
339     ssd1306_write_byte(0x8D, SSD1306_CMD);//--set Charge Pump enable/disable
340     ssd1306_write_byte(0x14, SSD1306_CMD);//--set(0x10) disable
341     ssd1306_write_byte(0xA4, SSD1306_CMD);// Disable Entire Display On (0xa4/0xa5)
342     ssd1306_write_byte(0xA6, SSD1306_CMD);// Disable Inverse Display On (0xa6/a7) 
343     ssd1306_write_byte(0xAF, SSD1306_CMD);//--turn on oled panel
344 
345     ssd1306_display_on();
346     ssd1306_clear_screen(0xff);
347     
348 }
349 
350 static int ssd1306_detect(struct i2c_adapter *adapter, int address, int kind)
351 {    
352     printk("ssd1306_detect
");
353 
354     ssd1306_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
355     ssd1306_client->addr    = address;
356     ssd1306_client->adapter = adapter;
357     ssd1306_client->driver  = &ssd1306_driver;
358     strcpy(ssd1306_client->name, "ssd1306");
359     
360     i2c_attach_client(ssd1306_client);
361     
362     ssd1306_init();
363 
364     ssd1306_clear_screen(0x00);
365     ssd1306_display_off();
366 
367     ssd1306_display_string(18, 0, "hello, Linux!", 16, 1);
368     ssd1306_display_string(0, 16, "this is an i2c driver demo!", 16, 1);
369     ssd1306_refresh_gram();
370     ssd1306_display_on();
371     
372     return 0;
373 }
374 
375 static int ssd1306_attach_adapter(struct i2c_adapter *adapter)
376 {
377     return i2c_probe(adapter, &addr_data, ssd1306_detect);
378 }
379 
380 static int ssd1306_detach_client(struct i2c_client *client)
381 {
382     printk("ssd1306_detach
");
383 
384     ssd1306_display_off();
385     ssd1306_clear_screen(0x00);
386     
387     i2c_detach_client(client);
388 
389     return 0;
390 }
391 
392 
393 static int ssd1306_module_init(void)
394 {
395     i2c_add_driver(&ssd1306_driver);
396     return 0;
397 }
398 
399 static void ssd1306_module_exit(void)
400 {
401     i2c_del_driver(&ssd1306_driver);
402 }
403 
404 module_init(ssd1306_module_init);
405 module_exit(ssd1306_module_exit);
406 
407 MODULE_LICENSE("GPL");

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原文地址：https://www.cnblogs.com/hackfun/p/5990069.html