理解I2C設備驅動框架，主要圍繞四個結構體去分析就容易了。
struct i2c_algorithm：提供I2C協議的實現的操作，如：master_xfer實現數據收發的最基本方法。
struct i2c_adapter：每一個i2c_adapter都代表一個I2C物理接口，一個cpu可以有多個I2C接口（i2c_adapter），i2c_algorithm就是為i2c_adapter提供I2C協議的實現。每增加一個i2c接口，即是向i2c_core.c注冊一個i2c_adapter
struct i2c_driver：代表著一類I2C從機設備的驅動，比如：at24cxx的驅動，不同類型的I2C從機需要注冊不同的i2c_driver，如：ssd1306的驅動不同於at24cxx的驅動。每增加一個類型的I2C從機設備，都要向i2c_core.c注冊一個i2c_driver
struct i2c_client：代表具體的某一個I2C從機設備，如：at24cxx系列的設備，有at24c01，at24c02等，每增加一個at24cxx設備，都要注冊一個i2c_client。只有I2C從機設備被探測到，i2c_client才會被注冊。
這四者的關系可以分為：i2c_algorithm和i2c_adapter一起驅動I2C總線，i2c_driver和i2c_client一起實現設備驅動。
注：linux目前只支持I2C主機模式。本文引用內核源碼中i2c-algo-bit.c和i2c-gpio.c文件來講解， i2c_driver由驅動開發者根據特定的設備提供，這裡引用作者提供的ssd1306.c。i2c-algo-bit.c和i2c-gpio.c共同實現IO模擬I2C。
i2c-algo-bit.c提供了一個i2c_algorithm，i2c-gpio.c提供了一個i2c_adapter。
i2c-algo-bit.c通過以下代碼綁定到i2c-gpio.c
i2c-algo-bit.c
static const struct i2c_algorithm i2c_bit_algo = {
.master_xfer = bit_xfer,
.functionality = bit_func,
};
static int i2c_bit_prepare_bus(struct i2c_adapter *adap)
{
... ...
adap->algo = &i2c_bit_algo;
... ...
return 0;
}
int i2c_bit_add_bus(struct i2c_adapter *adap)
{
... ...
err = i2c_bit_prepare_bus(adap);
... ...
return i2c_add_adapter(adap);
}
i2c-gpio.c
static int __init i2c_gpio_probe(struct platform_device *pdev)
{
struct i2c_gpio_platform_data *pdata;
struct i2c_algo_bit_data *bit_data;
struct i2c_adapter *adap;
... ...
pdata = pdev->dev.platform_data;
... ...
i2c_bit_add_bus(adap);
... ...
}
這裡就注冊了一個i2c_adapter。
要驅動ssd1306，因此對應地要提供一個i2c_driver，與i2c_adapter建立關系。
ssd1306.c
static struct i2c_driver ssd1306_driver = {
.driver = {
.name = "ssd1306",
},
.id = I2C_DRIVERID_I2CDEV,
.attach_adapter = ssd1306_attach_adapter,
.detach_client = ssd1306_detach_client,
};
static int ssd1306_module_init(void)
{
i2c_add_driver(&ssd1306_driver);
return 0;
}
i2c_driver和i2c_adapter是怎樣建立關系的呢？
I2c_core.c負責橋接i2c_driver和i2c_adapter建立關系，在i2c_driver和i2c_adapter注冊的時候，兩者都會調用driver->attach_adapter(adapter)
int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
{
... ...
driver->attach_adapter(adapter);
... ...
return 0;
}
static int i2c_register_adapter(struct i2c_adapter *adap)
{
... ...
driver->attach_adapter(adap);
... ...
}
driver->attach_adapter(adapter)實際上調用
1 static int ssd1306_attach_adapter(struct i2c_adapter *adapter)
2 {
3 return i2c_probe(adapter, &addr_data, ssd1306_detect);
4 }
I2c_probe()函數的作用就是，探測是否存在ssd1306這個設備，是怎樣探測的呢？就是通過發送從機地址到ssd1306，如果ssd1306返回應答信號，就認為探測到了。
int i2c_probe(struct i2c_adapter *adapter,
struct i2c_client_address_data *address_data,
int (*found_proc) (struct i2c_adapter *, int, int))
{
... ...
i2c_probe_address(adapter,
address_data->probe[i + 1],
-1, found_proc);
... ...
}
代碼太多，簡化函數調用關系如下：
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);實際調用的是bit_xfer()
探測到ssd1306後，其實也就說明了探測到的I2C地址有效， 還需要注冊一個描述SSD1306的i2c_client。
static int ssd1306_detect(struct i2c_adapter *adapter, int address, int kind)
{
printk("ssd1306_detect\n");
ssd1306_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
ssd1306_client->addr = address;
ssd1306_client->adapter = adapter;
ssd1306_client->driver = &ssd1306_driver;
strcpy(ssd1306_client->name, "ssd1306");
i2c_attach_client(ssd1306_client);
... ...
}
先轉下話題。
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 }
這裡實際上是注冊了一個platform_driver，我們還要對應的為他注冊一個platform_device，
這個platform_device提供了硬件相關的設置，如指定那兩個io口為SCL和SDA。
I2c_gpio_dev.c中
static struct i2c_gpio_platform_data i2c_dev = {
.sda_pin = S3C2410_GPG6,
.scl_pin = S3C2410_GPG5,
.udelay = 0,
.timeout = 0,
.sda_is_open_drain = 1,
.scl_is_open_drain = 1,
.scl_is_output_only = 1
};
static struct platform_device i2c_platform_dev = {
.name = "i2c-gpio",
.id = -1,
.dev = {
.release = i2c_dev_release,
.platform_data = (void *)&i2c_dev,
},
};
static int i2c_dev_init(void)
{
platform_device_register(&i2c_platform_dev);
return 0;
}
如果platform_device和platform_driver匹配，就會調用i2c_gpio_probe()
static int __init i2c_gpio_probe(struct platform_device *pdev)
{
struct i2c_gpio_platform_data *pdata;
struct i2c_algo_bit_data *bit_data;
struct i2c_adapter *adap;
... ...
pdata = pdev->dev.platform_data;
... ...
i2c_bit_add_bus(adap);
... ...
}
只有platform_device和platform_driver匹配才能注冊i2c_adapter。
到這裡，就可以操作ssd1306了。ssd1306寫一個字節的操作：
static void ssd1306_write_byte(uint8_t chData, uint8_t chCmd)
{
uint8_t cmd = 0x00;
if (chCmd) {
cmd = 0x40;
} else {
cmd = 0x00;
}
i2c_smbus_write_byte_data(ssd1306_client, cmd, chData);
}
實際上調用了i2c_smbus_write_byte_data()
I2c_core.c提供了幾個I2C的讀寫函數：
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)
運行代碼
注：由於源碼的i2c-gpio-bit.c只支持具有開漏輸入輸出功能的IO模擬I2C， 而我的開發板已經沒有具有開漏輸入輸出功能的IO了，只能使用普通的上啦輸入輸出IO，對SDA的讀寫操作，需要切換輸入輸出方向。因此我把i2c-gpio-bit.c改成普通IO操作SDA，命名為my-i2c-gpio-bit.c，同時i2c-gpio-bit.h和i2c-gpio.c也要做相應改動，分別改為my-i2c-gpio-bit.h和my-i2c-gpio.c。如果使用具有開漏輸入輸出功能的IO，可以直接使用i2c-gpio-bit.c，i2c-gpio-bit.h，i2c-gpio.c。
代碼
i2c_gpio_dev.c
#include <linux/module.h>
#include <linux/version.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/timer.h>
#include <linux/init.h>
#include <linux/serial_core.h>
#include <linux/platform_device.h>
#include <linux/gpio_keys.h>
#include <linux/input.h>
#include <linux/irq.h>
#include <linux/i2c-gpio.h>
#include <asm/gpio.h>
#include <asm/io.h>
#include <asm/arch/regs-gpio.h>
/* [cgw]: */
static struct i2c_gpio_platform_data i2c_dev = {
.sda_pin = S3C2410_GPG6,
.scl_pin = S3C2410_GPG5,
.udelay = 0,
.timeout = 0,
.sda_is_open_drain = 1,
.scl_is_open_drain = 1,
.scl_is_output_only = 1
};
static void i2c_dev_release(struct device * dev)
{
printk("i2c_dev_release! \n");
}
/* [cgw]: 分配一個平台設備 */
static struct platform_device i2c_platform_dev = {
.name = "i2c-gpio",
.id = -1,
.dev = {
.release = i2c_dev_release,
.platform_data = (void *)&i2c_dev,
},
};
static int i2c_dev_init(void)
{
/* [cgw]: 注冊i2c_platform_dev平台設備 */
platform_device_register(&i2c_platform_dev);
return 0;
}
static void i2c_dev_exit(void)
{
/* [cgw]: 注銷i2c_platform_dev平台設備 */
platform_device_unregister(&i2c_platform_dev);
}
module_init(i2c_dev_init);
module_exit(i2c_dev_exit);
MODULE_LICENSE("GPL");
ssd1306.c
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/i2c.h>
#include <linux/mutex.h>
#include <linux/fs.h>
#include <asm/uaccess.h>
#define SSD1306_CMD 0
#define SSD1306_DAT 1
#define SSD1306_WIDTH 128
#define SSD1306_HEIGHT 64
static uint8_t s_chDispalyBuffer[128][8];
const uint8_t c_chFont1608[95][16] = {
{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*" ",0*/
{0x00,0x00,0x00,0x00,0x00,0x00,0x1F,0xCC,0x00,0x0C,0x00,0x00,0x00,0x00,0x00,0x00},/*"!",1*/
{0x00,0x00,0x08,0x00,0x30,0x00,0x60,0x00,0x08,0x00,0x30,0x00,0x60,0x00,0x00,0x00},/*""",2*/
{0x02,0x20,0x03,0xFC,0x1E,0x20,0x02,0x20,0x03,0xFC,0x1E,0x20,0x02,0x20,0x00,0x00},/*"#",3*/
{0x00,0x00,0x0E,0x18,0x11,0x04,0x3F,0xFF,0x10,0x84,0x0C,0x78,0x00,0x00,0x00,0x00},/*"$",4*/
{0x0F,0x00,0x10,0x84,0x0F,0x38,0x00,0xC0,0x07,0x78,0x18,0x84,0x00,0x78,0x00,0x00},/*"%",5*/
{0x00,0x78,0x0F,0x84,0x10,0xC4,0x11,0x24,0x0E,0x98,0x00,0xE4,0x00,0x84,0x00,0x08},/*"&",6*/
{0x08,0x00,0x68,0x00,0x70,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*"'",7*/
{0x00,0x00,0x00,0x00,0x00,0x00,0x07,0xE0,0x18,0x18,0x20,0x04,0x40,0x02,0x00,0x00},/*"(",8*/
{0x00,0x00,0x40,0x02,0x20,0x04,0x18,0x18,0x07,0xE0,0x00,0x00,0x00,0x00,0x00,0x00},/*")",9*/
{0x02,0x40,0x02,0x40,0x01,0x80,0x0F,0xF0,0x01,0x80,0x02,0x40,0x02,0x40,0x00,0x00},/*"*",10*/
{0x00,0x80,0x00,0x80,0x00,0x80,0x0F,0xF8,0x00,0x80,0x00,0x80,0x00,0x80,0x00,0x00},/*"+",11*/
{0x00,0x01,0x00,0x0D,0x00,0x0E,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*",",12*/
{0x00,0x00,0x00,0x80,0x00,0x80,0x00,0x80,0x00,0x80,0x00,0x80,0x00,0x80,0x00,0x80},/*"-",13*/
{0x00,0x00,0x00,0x0C,0x00,0x0C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*".",14*/
{0x00,0x00,0x00,0x06,0x00,0x18,0x00,0x60,0x01,0x80,0x06,0x00,0x18,0x00,0x20,0x00},/*"/",15*/
{0x00,0x00,0x07,0xF0,0x08,0x08,0x10,0x04,0x10,0x04,0x08,0x08,0x07,0xF0,0x00,0x00},/*"0",16*/
{0x00,0x00,0x08,0x04,0x08,0x04,0x1F,0xFC,0x00,0x04,0x00,0x04,0x00,0x00,0x00,0x00},/*"1",17*/
{0x00,0x00,0x0E,0x0C,0x10,0x14,0x10,0x24,0x10,0x44,0x11,0x84,0x0E,0x0C,0x00,0x00},/*"2",18*/
{0x00,0x00,0x0C,0x18,0x10,0x04,0x11,0x04,0x11,0x04,0x12,0x88,0x0C,0x70,0x00,0x00},/*"3",19*/
{0x00,0x00,0x00,0xE0,0x03,0x20,0x04,0x24,0x08,0x24,0x1F,0xFC,0x00,0x24,0x00,0x00},/*"4",20*/
{0x00,0x00,0x1F,0x98,0x10,0x84,0x11,0x04,0x11,0x04,0x10,0x88,0x10,0x70,0x00,0x00},/*"5",21*/
{0x00,0x00,0x07,0xF0,0x08,0x88,0x11,0x04,0x11,0x04,0x18,0x88,0x00,0x70,0x00,0x00},/*"6",22*/
{0x00,0x00,0x1C,0x00,0x10,0x00,0x10,0xFC,0x13,0x00,0x1C,0x00,0x10,0x00,0x00,0x00},/*"7",23*/
{0x00,0x00,0x0E,0x38,0x11,0x44,0x10,0x84,0x10,0x84,0x11,0x44,0x0E,0x38,0x00,0x00},/*"8",24*/
{0x00,0x00,0x07,0x00,0x08,0x8C,0x10,0x44,0x10,0x44,0x08,0x88,0x07,0xF0,0x00,0x00},/*"9",25*/
{0x00,0x00,0x00,0x00,0x00,0x00,0x03,0x0C,0x03,0x0C,0x00,0x00,0x00,0x00,0x00,0x00},/*":",26*/
{0x00,0x00,0x00,0x00,0x00,0x01,0x01,0x06,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*";",27*/
{0x00,0x00,0x00,0x80,0x01,0x40,0x02,0x20,0x04,0x10,0x08,0x08,0x10,0x04,0x00,0x00},/*"<",28*/
{0x02,0x20,0x02,0x20,0x02,0x20,0x02,0x20,0x02,0x20,0x02,0x20,0x02,0x20,0x00,0x00},/*"=",29*/
{0x00,0x00,0x10,0x04,0x08,0x08,0x04,0x10,0x02,0x20,0x01,0x40,0x00,0x80,0x00,0x00},/*">",30*/
{0x00,0x00,0x0E,0x00,0x12,0x00,0x10,0x0C,0x10,0x6C,0x10,0x80,0x0F,0x00,0x00,0x00},/*"?",31*/
{0x03,0xE0,0x0C,0x18,0x13,0xE4,0x14,0x24,0x17,0xC4,0x08,0x28,0x07,0xD0,0x00,0x00},/*"@",32*/
{0x00,0x04,0x00,0x3C,0x03,0xC4,0x1C,0x40,0x07,0x40,0x00,0xE4,0x00,0x1C,0x00,0x04},/*"A",33*/
{0x10,0x04,0x1F,0xFC,0x11,0x04,0x11,0x04,0x11,0x04,0x0E,0x88,0x00,0x70,0x00,0x00},/*"B",34*/
{0x03,0xE0,0x0C,0x18,0x10,0x04,0x10,0x04,0x10,0x04,0x10,0x08,0x1C,0x10,0x00,0x00},/*"C",35*/
{0x10,0x04,0x1F,0xFC,0x10,0x04,0x10,0x04,0x10,0x04,0x08,0x08,0x07,0xF0,0x00,0x00},/*"D",36*/
{0x10,0x04,0x1F,0xFC,0x11,0x04,0x11,0x04,0x17,0xC4,0x10,0x04,0x08,0x18,0x00,0x00},/*"E",37*/
{0x10,0x04,0x1F,0xFC,0x11,0x04,0x11,0x00,0x17,0xC0,0x10,0x00,0x08,0x00,0x00,0x00},/*"F",38*/
{0x03,0xE0,0x0C,0x18,0x10,0x04,0x10,0x04,0x10,0x44,0x1C,0x78,0x00,0x40,0x00,0x00},/*"G",39*/
{0x10,0x04,0x1F,0xFC,0x10,0x84,0x00,0x80,0x00,0x80,0x10,0x84,0x1F,0xFC,0x10,0x04},/*"H",40*/
{0x00,0x00,0x10,0x04,0x10,0x04,0x1F,0xFC,0x10,0x04,0x10,0x04,0x00,0x00,0x00,0x00},/*"I",41*/
{0x00,0x03,0x00,0x01,0x10,0x01,0x10,0x01,0x1F,0xFE,0x10,0x00,0x10,0x00,0x00,0x00},/*"J",42*/
{0x10,0x04,0x1F,0xFC,0x11,0x04,0x03,0x80,0x14,0x64,0x18,0x1C,0x10,0x04,0x00,0x00},/*"K",43*/
{0x10,0x04,0x1F,0xFC,0x10,0x04,0x00,0x04,0x00,0x04,0x00,0x04,0x00,0x0C,0x00,0x00},/*"L",44*/
{0x10,0x04,0x1F,0xFC,0x1F,0x00,0x00,0xFC,0x1F,0x00,0x1F,0xFC,0x10,0x04,0x00,0x00},/*"M",45*/
{0x10,0x04,0x1F,0xFC,0x0C,0x04,0x03,0x00,0x00,0xE0,0x10,0x18,0x1F,0xFC,0x10,0x00},/*"N",46*/
{0x07,0xF0,0x08,0x08,0x10,0x04,0x10,0x04,0x10,0x04,0x08,0x08,0x07,0xF0,0x00,0x00},/*"O",47*/
{0x10,0x04,0x1F,0xFC,0x10,0x84,0x10,0x80,0x10,0x80,0x10,0x80,0x0F,0x00,0x00,0x00},/*"P",48*/
{0x07,0xF0,0x08,0x18,0x10,0x24,0x10,0x24,0x10,0x1C,0x08,0x0A,0x07,0xF2,0x00,0x00},/*"Q",49*/
{0x10,0x04,0x1F,0xFC,0x11,0x04,0x11,0x00,0x11,0xC0,0x11,0x30,0x0E,0x0C,0x00,0x04},/*"R",50*/
{0x00,0x00,0x0E,0x1C,0x11,0x04,0x10,0x84,0x10,0x84,0x10,0x44,0x1C,0x38,0x00,0x00},/*"S",51*/
{0x18,0x00,0x10,0x00,0x10,0x04,0x1F,0xFC,0x10,0x04,0x10,0x00,0x18,0x00,0x00,0x00},/*"T",52*/
{0x10,0x00,0x1F,0xF8,0x10,0x04,0x00,0x04,0x00,0x04,0x10,0x04,0x1F,0xF8,0x10,0x00},/*"U",53*/
{0x10,0x00,0x1E,0x00,0x11,0xE0,0x00,0x1C,0x00,0x70,0x13,0x80,0x1C,0x00,0x10,0x00},/*"V",54*/
{0x1F,0xC0,0x10,0x3C,0x00,0xE0,0x1F,0x00,0x00,0xE0,0x10,0x3C,0x1F,0xC0,0x00,0x00},/*"W",55*/
{0x10,0x04,0x18,0x0C,0x16,0x34,0x01,0xC0,0x01,0xC0,0x16,0x34,0x18,0x0C,0x10,0x04},/*"X",56*/
{0x10,0x00,0x1C,0x00,0x13,0x04,0x00,0xFC,0x13,0x04,0x1C,0x00,0x10,0x00,0x00,0x00},/*"Y",57*/
{0x08,0x04,0x10,0x1C,0x10,0x64,0x10,0x84,0x13,0x04,0x1C,0x04,0x10,0x18,0x00,0x00},/*"Z",58*/
{0x00,0x00,0x00,0x00,0x00,0x00,0x7F,0xFE,0x40,0x02,0x40,0x02,0x40,0x02,0x00,0x00},/*"[",59*/
{0x00,0x00,0x30,0x00,0x0C,0x00,0x03,0x80,0x00,0x60,0x00,0x1C,0x00,0x03,0x00,0x00},/*"\",60*/
{0x00,0x00,0x40,0x02,0x40,0x02,0x40,0x02,0x7F,0xFE,0x00,0x00,0x00,0x00,0x00,0x00},/*"]",61*/
{0x00,0x00,0x00,0x00,0x20,0x00,0x40,0x00,0x40,0x00,0x40,0x00,0x20,0x00,0x00,0x00},/*"^",62*/
{0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01},/*"_",63*/
{0x00,0x00,0x40,0x00,0x40,0x00,0x20,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*"`",64*/
{0x00,0x00,0x00,0x98,0x01,0x24,0x01,0x44,0x01,0x44,0x01,0x44,0x00,0xFC,0x00,0x04},/*"a",65*/
{0x10,0x00,0x1F,0xFC,0x00,0x88,0x01,0x04,0x01,0x04,0x00,0x88,0x00,0x70,0x00,0x00},/*"b",66*/
{0x00,0x00,0x00,0x70,0x00,0x88,0x01,0x04,0x01,0x04,0x01,0x04,0x00,0x88,0x00,0x00},/*"c",67*/
{0x00,0x00,0x00,0x70,0x00,0x88,0x01,0x04,0x01,0x04,0x11,0x08,0x1F,0xFC,0x00,0x04},/*"d",68*/
{0x00,0x00,0x00,0xF8,0x01,0x44,0x01,0x44,0x01,0x44,0x01,0x44,0x00,0xC8,0x00,0x00},/*"e",69*/
{0x00,0x00,0x01,0x04,0x01,0x04,0x0F,0xFC,0x11,0x04,0x11,0x04,0x11,0x00,0x18,0x00},/*"f",70*/
{0x00,0x00,0x00,0xD6,0x01,0x29,0x01,0x29,0x01,0x29,0x01,0xC9,0x01,0x06,0x00,0x00},/*"g",71*/
{0x10,0x04,0x1F,0xFC,0x00,0x84,0x01,0x00,0x01,0x00,0x01,0x04,0x00,0xFC,0x00,0x04},/*"h",72*/
{0x00,0x00,0x01,0x04,0x19,0x04,0x19,0xFC,0x00,0x04,0x00,0x04,0x00,0x00,0x00,0x00},/*"i",73*/
{0x00,0x00,0x00,0x03,0x00,0x01,0x01,0x01,0x19,0x01,0x19,0xFE,0x00,0x00,0x00,0x00},/*"j",74*/
{0x10,0x04,0x1F,0xFC,0x00,0x24,0x00,0x40,0x01,0xB4,0x01,0x0C,0x01,0x04,0x00,0x00},/*"k",75*/
{0x00,0x00,0x10,0x04,0x10,0x04,0x1F,0xFC,0x00,0x04,0x00,0x04,0x00,0x00,0x00,0x00},/*"l",76*/
{0x01,0x04,0x01,0xFC,0x01,0x04,0x01,0x00,0x01,0xFC,0x01,0x04,0x01,0x00,0x00,0xFC},/*"m",77*/
{0x01,0x04,0x01,0xFC,0x00,0x84,0x01,0x00,0x01,0x00,0x01,0x04,0x00,0xFC,0x00,0x04},/*"n",78*/
{0x00,0x00,0x00,0xF8,0x01,0x04,0x01,0x04,0x01,0x04,0x01,0x04,0x00,0xF8,0x00,0x00},/*"o",79*/
{0x01,0x01,0x01,0xFF,0x00,0x85,0x01,0x04,0x01,0x04,0x00,0x88,0x00,0x70,0x00,0x00},/*"p",80*/
{0x00,0x00,0x00,0x70,0x00,0x88,0x01,0x04,0x01,0x04,0x01,0x05,0x01,0xFF,0x00,0x01},/*"q",81*/
{0x01,0x04,0x01,0x04,0x01,0xFC,0x00,0x84,0x01,0x04,0x01,0x00,0x01,0x80,0x00,0x00},/*"r",82*/
{0x00,0x00,0x00,0xCC,0x01,0x24,0x01,0x24,0x01,0x24,0x01,0x24,0x01,0x98,0x00,0x00},/*"s",83*/
{0x00,0x00,0x01,0x00,0x01,0x00,0x07,0xF8,0x01,0x04,0x01,0x04,0x00,0x00,0x00,0x00},/*"t",84*/
{0x01,0x00,0x01,0xF8,0x00,0x04,0x00,0x04,0x00,0x04,0x01,0x08,0x01,0xFC,0x00,0x04},/*"u",85*/
{0x01,0x00,0x01,0x80,0x01,0x70,0x00,0x0C,0x00,0x10,0x01,0x60,0x01,0x80,0x01,0x00},/*"v",86*/
{0x01,0xF0,0x01,0x0C,0x00,0x30,0x01,0xC0,0x00,0x30,0x01,0x0C,0x01,0xF0,0x01,0x00},/*"w",87*/
{0x00,0x00,0x01,0x04,0x01,0x8C,0x00,0x74,0x01,0x70,0x01,0x8C,0x01,0x04,0x00,0x00},/*"x",88*/
{0x01,0x01,0x01,0x81,0x01,0x71,0x00,0x0E,0x00,0x18,0x01,0x60,0x01,0x80,0x01,0x00},/*"y",89*/
{0x00,0x00,0x01,0x84,0x01,0x0C,0x01,0x34,0x01,0x44,0x01,0x84,0x01,0x0C,0x00,0x00},/*"z",90*/
{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x00,0x3E,0xFC,0x40,0x02,0x40,0x02},/*"{",91*/
{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xFF,0xFF,0x00,0x00,0x00,0x00,0x00,0x00},/*"|",92*/
{0x00,0x00,0x40,0x02,0x40,0x02,0x3E,0xFC,0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00},/*"}",93*/
{0x00,0x00,0x60,0x00,0x80,0x00,0x80,0x00,0x40,0x00,0x40,0x00,0x20,0x00,0x20,0x00},/*"~",94*/
};
static unsigned short normal_i2c[] = { 0x3C, I2C_CLIENT_END };
I2C_CLIENT_INSMOD_1(ssd1306);
static int ssd1306_attach_adapter(struct i2c_adapter *adapter);
static int ssd1306_detach_client(struct i2c_client *client);
static struct i2c_driver ssd1306_driver = {
.driver = {
.name = "ssd1306",
},
.id = I2C_DRIVERID_I2CDEV,
.attach_adapter = ssd1306_attach_adapter,
.detach_client = ssd1306_detach_client,
};
struct i2c_client *ssd1306_client;
static void ssd1306_write_byte(uint8_t chData, uint8_t chCmd)
{
uint8_t cmd = 0x00;
if (chCmd) {
cmd = 0x40;
} else {
cmd = 0x00;
}
i2c_smbus_write_byte_data(ssd1306_client, cmd, chData);
}
void ssd1306_display_on(void)
{
ssd1306_write_byte(0x8D, SSD1306_CMD);
ssd1306_write_byte(0x14, SSD1306_CMD);
ssd1306_write_byte(0xAF, SSD1306_CMD);
}
/**
* @brief OLED turns off
*
* @param None
*
* @retval None
**/
void ssd1306_display_off(void)
{
ssd1306_write_byte(0x8D, SSD1306_CMD);
ssd1306_write_byte(0x10, SSD1306_CMD);
ssd1306_write_byte(0xAE, SSD1306_CMD);
}
void ssd1306_refresh_gram(void)
{
uint8_t i, j;
for (i = 0; i < 8; i ++) {
ssd1306_write_byte(0xB0 + i, SSD1306_CMD);
ssd1306_write_byte(0x02, SSD1306_CMD);
ssd1306_write_byte(0x10, SSD1306_CMD);
for (j = 0; j < 128; j ++) {
ssd1306_write_byte(s_chDispalyBuffer[j][i], SSD1306_DAT);
}
}
}
void ssd1306_clear_screen(uint8_t chFill)
{
memset(s_chDispalyBuffer,chFill, sizeof(s_chDispalyBuffer));
ssd1306_refresh_gram();
}
/**
* @brief Draws a piont on the screen
*
* @param chXpos: Specifies the X position
* @param chYpos: Specifies the Y position
* @param chPoint: 0: the point turns off 1: the piont turns on
*
* @retval None
**/
void ssd1306_draw_point(uint8_t chXpos, uint8_t chYpos, uint8_t chPoint)
{
uint8_t chPos, chBx, chTemp = 0;
if (chXpos > 127 || chYpos > 63) {
return;
}
chPos = 7 - chYpos / 8; //
chBx = chYpos % 8;
chTemp = 1 << (7 - chBx);
if (chPoint) {
s_chDispalyBuffer[chXpos][chPos] |= chTemp;
} else {
s_chDispalyBuffer[chXpos][chPos] &= ~chTemp;
}
}
/**
* @brief Fills a rectangle
*
* @param chXpos1: Specifies the X position 1 (X top left position)
* @param chYpos1: Specifies the Y position 1 (Y top left position)
* @param chXpos2: Specifies the X position 2 (X bottom right position)
* @param chYpos3: Specifies the Y position 2 (Y bottom right position)
*
* @retval
**/
void ssd1306_fill_screen(uint8_t chXpos1, uint8_t chYpos1, uint8_t chXpos2, uint8_t chYpos2, uint8_t chDot)
{
uint8_t chXpos, chYpos;
for (chXpos = chXpos1; chXpos <= chXpos2; chXpos ++) {
for (chYpos = chYpos1; chYpos <= chYpos2; chYpos ++) {
ssd1306_draw_point(chXpos, chYpos, chDot);
}
}
ssd1306_refresh_gram();
}
/**
* @brief Displays one character at the specified position
*
* @param chXpos: Specifies the X position
* @param chYpos: Specifies the Y position
* @param chSize:
* @param chMode
* @retval
**/
void ssd1306_display_char(uint8_t chXpos, uint8_t chYpos, uint8_t chChr, uint8_t chSize, uint8_t chMode)
{
uint8_t i, j;
uint8_t chTemp, chYpos0 = chYpos;
chChr = chChr - ' ';
for (i = 0; i < chSize; i ++) {
if (chMode) {
chTemp = c_chFont1608[chChr][i];
} else {
chTemp = ~c_chFont1608[chChr][i];
}
for (j = 0; j < 8; j ++) {
if (chTemp & 0x80) {
ssd1306_draw_point(chXpos, chYpos, 1);
} else {
ssd1306_draw_point(chXpos, chYpos, 0);
}
chTemp <<= 1;
chYpos ++;
if ((chYpos - chYpos0) == chSize) {
chYpos = chYpos0;
chXpos ++;
break;
}
}
}
}
/**
* @brief Displays a string on the screen
*
* @param chXpos: Specifies the X position
* @param chYpos: Specifies the Y position
* @param pchString: Pointer to a string to display on the screen
*
* @retval None
**/
void ssd1306_display_string(uint8_t chXpos, uint8_t chYpos, const uint8_t *pchString, uint8_t chSize, uint8_t chMode)
{
while (*pchString != '\0') {
if (chXpos > (SSD1306_WIDTH - chSize / 2)) {
chXpos = 0;
chYpos += chSize;
if (chYpos > (SSD1306_HEIGHT - chSize)) {
chYpos = chXpos = 0;
ssd1306_clear_screen(0x00);
}
}
ssd1306_display_char(chXpos, chYpos, *pchString, chSize, chMode);
chXpos += chSize / 2;
pchString ++;
}
}
void ssd1306_init(void)
{
ssd1306_write_byte(0xAE, SSD1306_CMD);//--turn off oled panel
ssd1306_write_byte(0x00, SSD1306_CMD);//---set low column address
ssd1306_write_byte(0x10, SSD1306_CMD);//---set high column address
ssd1306_write_byte(0x40, SSD1306_CMD);//--set start line address Set Mapping RAM Display Start Line (0x00~0x3F)
ssd1306_write_byte(0x81, SSD1306_CMD);//--set contrast control register
ssd1306_write_byte(0xCF, SSD1306_CMD);// Set SEG Output Current Brightness
ssd1306_write_byte(0xA1, SSD1306_CMD);//--Set SEG/Column Mapping
ssd1306_write_byte(0xC0, SSD1306_CMD);//Set COM/Row Scan Direction
ssd1306_write_byte(0xA6, SSD1306_CMD);//--set normal display
ssd1306_write_byte(0xA8, SSD1306_CMD);//--set multiplex ratio(1 to 64)
ssd1306_write_byte(0x3f, SSD1306_CMD);//--1/64 duty
ssd1306_write_byte(0xD3, SSD1306_CMD);//-set display offset Shift Mapping RAM Counter (0x00~0x3F)
ssd1306_write_byte(0x00, SSD1306_CMD);//-not offset
ssd1306_write_byte(0xd5, SSD1306_CMD);//--set display clock divide ratio/oscillator frequency
ssd1306_write_byte(0x80, SSD1306_CMD);//--set divide ratio, Set Clock as 100 Frames/Sec
ssd1306_write_byte(0xD9, SSD1306_CMD);//--set pre-charge period
ssd1306_write_byte(0xF1, SSD1306_CMD);//Set Pre-Charge as 15 Clocks & Discharge as 1 Clock
ssd1306_write_byte(0xDA, SSD1306_CMD);//--set com pins hardware configuration
ssd1306_write_byte(0x12, SSD1306_CMD);
ssd1306_write_byte(0xDB, SSD1306_CMD);//--set vcomh
ssd1306_write_byte(0x40, SSD1306_CMD);//Set VCOM Deselect Level
ssd1306_write_byte(0x20, SSD1306_CMD);//-Set Page Addressing Mode (0x00/0x01/0x02)
ssd1306_write_byte(0x02, SSD1306_CMD);//
ssd1306_write_byte(0x8D, SSD1306_CMD);//--set Charge Pump enable/disable
ssd1306_write_byte(0x14, SSD1306_CMD);//--set(0x10) disable
ssd1306_write_byte(0xA4, SSD1306_CMD);// Disable Entire Display On (0xa4/0xa5)
ssd1306_write_byte(0xA6, SSD1306_CMD);// Disable Inverse Display On (0xa6/a7)
ssd1306_write_byte(0xAF, SSD1306_CMD);//--turn on oled panel
ssd1306_display_on();
ssd1306_clear_screen(0xff);
}
static int ssd1306_detect(struct i2c_adapter *adapter, int address, int kind)
{
printk("ssd1306_detect\n");
ssd1306_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
ssd1306_client->addr = address;
ssd1306_client->adapter = adapter;
ssd1306_client->driver = &ssd1306_driver;
strcpy(ssd1306_client->name, "ssd1306");
i2c_attach_client(ssd1306_client);
ssd1306_init();
ssd1306_clear_screen(0x00);
ssd1306_display_off();
ssd1306_display_string(18, 0, "hello, Linux!", 16, 1);
ssd1306_display_string(0, 16, "this is an i2c driver demo!", 16, 1);
ssd1306_refresh_gram();
ssd1306_display_on();
return 0;
}
static int ssd1306_attach_adapter(struct i2c_adapter *adapter)
{
return i2c_probe(adapter, &addr_data, ssd1306_detect);
}
static int ssd1306_detach_client(struct i2c_client *client)
{
printk("ssd1306_detach\n");
ssd1306_display_off();
ssd1306_clear_screen(0x00);
i2c_detach_client(client);
return 0;
}
static int ssd1306_module_init(void)
{
i2c_add_driver(&ssd1306_driver);
return 0;
}
static void ssd1306_module_exit(void)
{
i2c_del_driver(&ssd1306_driver);
}
module_init(ssd1306_module_init);
module_exit(ssd1306_module_exit);
MODULE_LICENSE("GPL");
