SPI的控制器驅動由平臺設備與平臺驅動來實現. 驅動后用spi_master對象來描述.在設備驅動中就可以通過函數spi_write, spi_read, spi_w8r16, spi_w8r8等函數來調用控制器.

"include/linux/spi/spi.h"

//讓spi->master指向的控制器對象發出len個字節數據，數據緩沖區地址由buf指針指向

static inline int spi_write(struct spi_device *spi, const void *buf, size_t len);

//讓spi->master指向的控制器對象接收len個字節數據，由buf指向指向的數據緩沖區存放

static inline int spi_read(struct spi_device *spi, void *buf, size_t len);

//讓spi->master指向的控制器對象發出數據后再接收數據

int spi_write_then_read(struct spi_device *spi, const void *txbuf, unsigned n_tx,

void *rxbuf, unsigned n_rx);

//讓spi->master控制器對象同時收發8位數據

static inline ssize_t spi_w8r8(struct spi_device *spi, u8 cmd);

//讓spi->master控制器對象同時發8位，接收16位數據.

static inline ssize_t spi_w8r16(struct spi_device *spi, u8 cmd);

屏:

流程：　命令/數據 –> spi控制器 —> 屏驅動ic的spi接口 —> ILI9340C(屏的驅動ic) –> 屏

屏的驅動ic的作用：根據接收到的命令和數據，配置屏的時序參數及在屏上刷出相應的像素數據.

也就是我們只要通過spi接口把屏的命令和數據交給屏的驅動ic即可，　讓驅動IC完成刷屏的操作.

//所有的lcd屏都會用到驅動IC的

//ILI9340C驅動ic內部有配置寄存器，我們需要通過spi接口配置驅動ic內部寄存器的值

模塊的引腳與板的連接:

reset --> PA8 //用于復位模塊

D/C --> PA7 //通過高低電平來區分數據線上的數據類型, command:0, data:1 .

//command其實就是表示數據線上發過去的是驅動ic內部寄存器的地址

//data表示數據線上發過去的數據就是寄存器要設的值

CS --> spi0_CS0 //片選線

SDI --> spi0_MOSI //數據線，發出驅動ic的寄存器地址和要設置的值

SDO --> spi0_MISO // 如不需要讀取驅動ic寄存器的值，可不接

SCLK --> spi0_CLK //時鐘線

LED --> 3.3v //背光電源

VCC --> 3.3v

GND --> GND

//通過時序圖可得知，模塊支持三線/四線的工作方式，四線是用D/C線區分數據線上的數據是寄存器地址或數據.　spi的工作時序方式是SPI_MODE_0(CPOL=0, CPHA=0), 也可以得知傳輸是以8位為單位.

//在內核里描述spi屏設備，并通過spi_board_info的platform_data提供連接屏reset和D/C引腳的GPIO.

描述設備的代碼:

#include

#include

struct sunxi_spi_config {

int bits_per_word; //8bit

int max_speed_hz; //80MHz

int mode; // pha,pol,LSB,etc..

} sunxi_data = {

8, 10000000, SPI_MODE_0

};

struct myspi_lcd_pdata {

int dc_io;

int reset_io;

}spi_lcd_pdata = {

GPIOA(7), GPIOA(8),

};

struct spi_board_info spi_infos[] = {

{

.modalias = "myspi_lcd",

.platform_data = &spi_lcd_pdata,

.controller_data = &sunxi_data,

.max_speed_hz = 10000000,

.bus_num = 0,

.chip_select = 0,

.mode = SPI_MODE_0,

},

};

static void __init sunxi_dev_init(void)

{

...

// 在最后一行

spi_register_board_info(spi_infos, ARRAY_SIZE(spi_infos));

}

//設備驅動的實現//

店家提供的c51里初始化屏的驅動代碼:

void write_command(uchar c) //發送驅動ic的寄存器地址

{

cs=0;

rs=0; // D/C 低電平

bitdata=c;

sda=bit7;scl=0;scl=1;

sda=bit6;scl=0;scl=1;

sda=bit5;scl=0;scl=1;

sda=bit4;scl=0;scl=1;

sda=bit3;scl=0;scl=1;

sda=bit2;scl=0;scl=1;

sda=bit1;scl=0;scl=1;

sda=bit0;scl=0;scl=1;

cs=1;

}

void write_data(uchar d) //給驅動ic傳輸數據使用

{

cs=0;

rs=1; // D/C　高電平

bitdata=d;

sda=bit7;scl=0;scl=1;

sda=bit6;scl=0;scl=1;

sda=bit5;scl=0;scl=1;

sda=bit4;scl=0;scl=1;

sda=bit3;scl=0;scl=1;

sda=bit2;scl=0;scl=1;

sda=bit1;scl=0;scl=1;

sda=bit0;scl=0;scl=1;

cs=1;

}

void lcd_initial()

{

reset=0;

delay(100);

reset=1;

delay(100);

write_command(0xCB);

write_data(0x39);

write_data(0x2C);

write_data(0x00);

write_data(0x34);

write_data(0x02);

write_command(0xCF);

write_data(0x00);

write_data(0XC1);

write_data(0X30);

write_command(0xE8);

write_data(0x85);

write_data(0x00);

write_data(0x78);

write_command(0xEA);

write_data(0x00);

write_data(0x00);

write_command(0xED);

write_data(0x64);

write_data(0x03);

write_data(0X12);

write_data(0X81);

write_command(0xF7);

write_data(0x20);

write_command(0xC0); //Power control

write_data(0x23); //VRH[5:0]

write_command(0xC1); //Power control

write_data(0x10); //SAP[2:0];BT[3:0]

write_command(0xC5); //VCM control

write_data(0x3e); //??±è?èμ÷?ú

write_data(0x28);

write_command(0xC7); //VCM control2

write_data(0x86); //--

write_command(0x36); // Memory Access Control

//??2?êy?aoá?áêú?áé??è·?ê??D??1??ü2?êy

//0x48 0x68êú?á

//0x28 0xE8 oá?á

write_data(0x48); //éè????è?êú?áé??è·?ê?

write_command(0x3A);

write_data(0x55);

write_command(0xB1);

write_data(0x00);

write_data(0x18);

write_command(0xB6); // Display Function Control

write_data(0x08);

write_data(0x82);

write_data(0x27);

write_command(0xF2); // 3Gamma Function Disable

write_data(0x00);

write_command(0x26); //Gamma curve selected

write_data(0x01);

write_command(0xE0); //Set Gamma

write_data(0x0F);

write_data(0x31);

write_data(0x2B);

write_data(0x0C);

write_data(0x0E);

write_data(0x08);

write_data(0x4E);

write_data(0xF1);

write_data(0x37);

write_data(0x07);

write_data(0x10);

write_data(0x03);

write_data(0x0E);

write_data(0x09);

write_data(0x00);

write_command(0XE1); //Set Gamma

write_data(0x00);

write_data(0x0E);

write_data(0x14);

write_data(0x03);

write_data(0x11);

write_data(0x07);

write_data(0x31);

write_data(0xC1);

write_data(0x48);

write_data(0x08);

write_data(0x0F);

write_data(0x0C);

write_data(0x31);

write_data(0x36);

write_data(0x0F);

write_command(0x11); //Exit Sleep

delay(120);

write_command(0x29); //Display on

write_command(0x2c);

}

///

參考上面驅動代碼實現的linux設備驅動:

#include

#include

#include

#include

#include

struct myspi_lcd_pdata {

int dc_io;

int reset_io;

};

struct spi_lcd_cmd{

u8 reg_addr; // command

u8 len; //需要從spi_lcd_datas數組里發出數據字節數

int delay_ms; //此命令發送數據完成后，需延時多久

}cmds[] = {

{0xCB, 5, 0},

{0xCF, 3, 0},

{0xEB, 3, 0},

{0xEA, 2, 0},

{0xED, 4, 0},

{0xF7, 1, 0},

{0xC0, 1, 0},

{0xC1, 1, 0},

{0xC5, 2, 0},

{0xC7, 1, 0},

{0x36, 1, 0},

{0x3A, 1, 0},

{0xB1, 2, 0},

{0xB6, 3, 0},

{0xF2, 1, 0},

{0x26, 1, 0},

{0xE0, 15, 0},

{0xE1, 15, 0},

{0x11, 0, 120},

{0x29, 0, 0},

{0x2c, 0, 0},

};

u8 spi_lcd_datas[] = {

0x39, 0x2c, 0x00, 0x34, 0x20, // command: 0xCB要發出的數據

0x00, 0xC1, 0x30, // command: 0xCF

0x85, 0x00, 0x78, // command: 0xEB

0x00, 0x00, // command: 0xEA

0x64, 0x03, 0x12, 0x81, // command: 0xED

0x20, // command: 0xF7

0x23, // command: 0xC0

0x10, // command: 0xC1

0x3e, 0x28, // command: 0xC5

0x86, // command: 0xC7

0x48, // command: 0x36

0x55, // command: 0x3A

0x00, 0x18, // command: 0xB1

0x08, 0x82, 0x27, // command: 0xB6

0x00, // command: 0xF2

0x01, // command: 0x26

0x0F, 0x31, 0x2B, 0x0C, 0x0E, 0x08, 0x4E, 0xF1, 0x37, 0x07, 0x10, 0x03, 0x0E, 0x09, 0x00, //command: 0xE0

0x00, 0x0E, 0x14, 0x03, 0x11, 0x07, 0x31, 0xC1, 0x48, 0x08, 0x0F, 0x0C, 0x31, 0x36, 0x0F, //command: 0xE1

};

void write_command(struct spi_device *spi, u8 cmd)

{

struct myspi_lcd_pdata *pdata = spi->dev.platform_data;

// dc , command:0

gpio_direction_output(pdata->dc_io, 0);

spi_write(spi, &cmd, 1);

}

void write_data(struct spi_device *spi, u8 data)

{

struct myspi_lcd_pdata *pdata = spi->dev.platform_data;

// dc , data:1

gpio_direction_output(pdata->dc_io, 1);

spi_write(spi, &data, 1);

}

//初始化spi_lcd

void spi_lcd_init(struct spi_device *spi)

{

struct myspi_lcd_pdata *pdata = spi->dev.platform_data;

int i, j, n;

// 屏復位

gpio_direction_output(pdata->reset_io, 0);

mdelay(100);

gpio_set_value(pdata->reset_io, 1);

mdelay(100);

n = 0; // n用于記錄數據數組spi_lcd_datas的位置

//發命令，并發出命令所需的數據

for (i = 0; i < ARRAY_SIZE(cmds); i++) //命令

{

write_command(spi, cmds[i].reg_addr);

for (j = 0; j < cmds[i].len; j++) //發出命令后，需要發出的數據

write_data(spi, spi_lcd_datas[n++]);

if (cmds[i].delay_ms) //如有延時則延時

mdelay(cmds[i].delay_ms);

}

}

//設置要刷屏的開始坐標

void addset(struct spi_device *spi, unsigned int x,unsigned int y)

{

write_command(spi, 0x2a); //發出x坐標

write_data(spi, x>>8);

write_data(spi, x&0xff);

write_command(spi, 0x2b); //發出y坐標

write_data(spi, y>>8);

write_data(spi, y&0xff);

write_command(spi, 0x2c);

}

int myprobe(struct spi_device *spi)

{

struct myspi_lcd_pdata *pdata = spi->dev.platform_data;

int ret;

int x, y;

u16 color0 = 0x001f; // RGB565, blue

u16 color1 = 0xf800; // red

u16 color2 = 0x07e0; // green

u16 color3 = 0xffff; // white

u16 color;

ret = gpio_request(pdata->reset_io, spi->modalias);

if (ret < 0)

goto err0;

ret = gpio_request(pdata->dc_io, spi->modalias);

if (ret < 0)

goto err1;

spi_lcd_init(spi); //初始化屏

addset(spi, 0, 0); //從屏的0,0坐標開始刷

//刷屏, 把整屏分成4塊，每塊顏色不同

// gpio_direction_output(pdata->dc_io, 1);

for (y = 0; y < 320; y++)

{

for (x = 0; x < 240; x++)

{

if (x < 120)

color = (y < 160) ? color0 : color1;

else

color = (y < 160) ? color2 : color3;

write_data(spi, color >> 8);

write_data(spi, color & 0xff);

}

}

printk("probe ...%s\n", spi->modalias);

return 0;

err1:

gpio_free(pdata->reset_io);

err0:

return ret;

}

int myremove(struct spi_device *spi)

{

struct myspi_lcd_pdata *pdata = spi->dev.platform_data;

gpio_free(pdata->dc_io);

gpio_free(pdata->reset_io);

printk("%s remove\n", spi->modalias);

return 0;

}

struct spi_device_id ids[] = {

{"myspi_lcd"},

{},

};

struct spi_driver myspi_drv = {

.driver = {

.owner = THIS_MODULE,

.name = "myspi_drv",

},

.probe = myprobe,

.remove = myremove,

.id_table = ids,

};

module_spi_driver(myspi_drv);

MODULE_LICENSE("GPL");

效果圖:

總結

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