GPIO模拟SPI通讯接口的驱动
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GPIO模拟SPI通讯接口的驱动一，某些时候我们会不得不使用GPIO来模拟SPI，I2C等通讯接口，如本例中，需要使用SPI接口发送9位的数据，如果使用linux内核提供的SPI子系统来做这个驱动是无法实现9位传输数据的。
二，用GPIO模拟SPI总的来说是比较简单，把相应的管脚配置成GPIO功能，再按需要配置管脚的输入输出方向，然后根据SPI总线的时序设定IO口的电平。
三，驱动代码如下，以备今后作参考：（linux-2.6.28 + TCC8900, 这个驱动是用来控制LCD的初始化的（型号为LW350AC9001））#include <linux/module.h>#include <linux/types.h>#include <linux/kernel.h>#include <linux/init.h>#include <linux/ioport.h>#include <asm/uaccess.h>#include <linux/delay.h>#include <bsp.h>#include <asm/io.h>#define PDEBUG#ifdef PDEBUG#define PLOG(fmt,args...) printk(fmt,##args)#else#define PLOG(fmt,args...) /*do nothing*/#endif#define SPI_CMD 0#define SPI_DATA 1#define FUN_GPIO 0#define PIN_SDO 15 //GPIOF[15]#define PIN_SDI 14#define PIN_SCLK 16#define PIN_CS 29 //GPIOC[29]#define GPC_BASE 0xF0102080#define GPF_BASE 0xF0102140#define OFFSET_DAT 0x0#define OFFSET_EN 0x4#define OFFSET_FUN0 0x24#define OFFSET_FUN1 0x28#define OFFSET_FUN2 0x2c#define OFFSET_FUN3 0x30// select pin used for gpiostatic int tcc_set_pin_fun(int pin, int fun){if(pin<8)tcc_writel(((tcc_readl(GPF_BASE+OFFSET_FUN0) & ~(0x0f<<(4*pin))) | (fun<<(4 * pin))), GPF_BASE+OFFSET_FUN0);else if(pin<16)tcc_writel(((tcc_readl(GPF_BASE+OFFSET_FUN1) & ~(0x0f<<(4*(pin-8)))) | (fun<<(4 * (pin-8)))), GPF_BASE+OFFSET_FUN1);else if(pin<24)tcc_writel(((tcc_readl(GPF_BASE+OFFSET_FUN2) & ~(0x0f<<(4*(pin-16)))) | (fun<<(4 *(pin-16)))),GPF_BASE+OFFSET_FUN2);else if(pin<32)tcc_writel(((tcc_readl(GPF_BASE+OFFSET_FUN3) & ~(0x0f<<(4*(pin-24)))) | (fun<<(4 *(pin-24)))),GPF_BASE+OFFSET_FUN3);return 0;}static int tcc_set_cs_fun(void){tcc_writel(((tcc_readl(GPC_BASE+OFFSET_FUN3) & ~(0x0f<<(4*(PIN_CS-24)))) ),GPC_BASE+OFFSET_FUN3);return 0;}// set gpio direction, output: 1 for output, 0 for inputstatic int tcc_set_gpio_direction(int pin, int output){tcc_writel(((tcc_readl(GPF_BASE+OFFSET_EN) & ~(1<<pin)) | (output<< pin)),GPF_BASE+OFFSET_EN);return 0;}static int tcc_set_cs_output(void){tcc_writel(((tcc_readl(GPC_BASE+OFFSET_EN) | (1<< PIN_CS)) ),GPC_BASE+OFFSET_EN);return 0;}// set gpio pin level, high: 1, low: 0static int tcc_set_gpio_data(int pin, int level){tcc_writel(((tcc_readl(GPF_BASE+OFFSET_DAT) & ~(1<<pin) )| (level<< pin)),GPF_BASE+OFFSET_DAT);return 0;}static int tcc_set_cs_data(int level){tcc_writel(((tcc_readl(GPC_BASE+OFFSET_DAT) & ~(1<<PIN_CS) )| (level<< PIN_CS)), GPC_BASE+OFFSET_DAT);return 0;}// get gpio pin level, high: 1, low: 0static int tcc_get_gpio_data(int pin){return ((tcc_readl(GPF_BASE+OFFSET_DAT) >>pin) & 1);}void SPI_init(void){tcc_set_pin_fun(PIN_SDO, FUN_GPIO); //configure pin sdo and sda as GPIOtcc_set_pin_fun(PIN_SDI, FUN_GPIO);tcc_set_pin_fun(PIN_SCLK, FUN_GPIO);tcc_set_gpio_direction(PIN_SDO,1);tcc_set_gpio_direction(PIN_SDI,1);tcc_set_gpio_direction(PIN_SCLK,1);tcc_set_gpio_data(PIN_SDO,1);tcc_set_gpio_data(PIN_SDI,1);tcc_set_gpio_data(PIN_SCLK,1);tcc_set_cs_fun();tcc_set_cs_output();tcc_set_cs_data(1);}void SPI_send(bool is_parameter,unsigned char w_data){unsigned char vsignbit;//send DNC-bittcc_set_gpio_data(PIN_SCLK,0);tcc_set_gpio_data(PIN_SDO,is_parameter);ndelay(20);tcc_set_gpio_data(PIN_SCLK,1);ndelay(20);for(vsignbit=0x80;vsignbit>0;vsignbit>>=1) {tcc_set_gpio_data(PIN_SCLK,0);if(w_data&vsignbit)tcc_set_gpio_data(PIN_SDO,1);elsetcc_set_gpio_data(PIN_SDO,0);ndelay(20);tcc_set_gpio_data(PIN_SCLK,1);ndelay(20);}tcc_set_gpio_data(PIN_SDO,1);}unsigned char SPI_read(void){unsigned char vsignbit,r_data=0;tcc_set_gpio_direction(PIN_SDI,1);tcc_set_gpio_data(PIN_SDI,1);tcc_set_gpio_direction(PIN_SDI,0);for(vsignbit=0x80;vsignbit>0;vsignbit>>=1) {tcc_set_gpio_data(PIN_SCLK,0);ndelay(20);if(tcc_get_gpio_data(PIN_SDI)){r_data = r_data|vsignbit;}tcc_set_gpio_data(PIN_SCLK,1);ndelay(20);}return r_data;}static void set_value(){SPI_send(SPI_CMD, 0xB9);SPI_send(SPI_DATA, 0xFF);SPI_send(SPI_DATA, 0x83);SPI_send(SPI_DATA, 0x63);SPI_send(SPI_CMD, 0xB1);SPI_send(SPI_DATA, 0x81);SPI_send(SPI_DATA, 0x30);SPI_send(SPI_DATA, 0x02);SPI_send(SPI_DATA, 0x13);SPI_send(SPI_DATA, 0x11);SPI_send(SPI_DATA, 0x00);SPI_send(SPI_DATA, 0x3A);SPI_send(SPI_DATA, 0x42);SPI_send(SPI_DATA, 0x3F);SPI_send(SPI_DATA, 0x3F);SPI_send(SPI_CMD, 0x11);mdelay(150);SPI_send(SPI_CMD, 0x36);SPI_send(SPI_DATA, 0x08);SPI_send(SPI_CMD, 0x3A);SPI_send(SPI_DATA, 0x77);SPI_send(SPI_CMD, 0xB3);SPI_send(SPI_DATA,0x09);SPI_send(SPI_CMD, 0xB4);SPI_send(SPI_DATA, 0x08);SPI_send(SPI_DATA, 0x12);SPI_send(SPI_DATA, 0x72);SPI_send(SPI_DATA, 0x12);SPI_send(SPI_DATA, 0x06);SPI_send(SPI_DATA, 0x03);SPI_send(SPI_DATA, 0x54);SPI_send(SPI_DATA, 0x03);SPI_send(SPI_DATA, 0x4E);SPI_send(SPI_DATA, 0x00);SPI_send(SPI_DATA, 0x00);SPI_send(SPI_CMD, 0xBF);SPI_send(SPI_DATA, 0x00);SPI_send(SPI_DATA, 0x01);SPI_send(SPI_CMD, 0xB6);SPI_send(SPI_DATA, 0x00);SPI_send(SPI_CMD, 0xCC);SPI_send(SPI_DATA, 0x0A);mdelay(10);SPI_send(SPI_DATA, 0x40);SPI_send(SPI_DATA, 0x42);SPI_send(SPI_DATA, 0xC1);SPI_send(SPI_DATA, 0x4B);SPI_send(SPI_DATA, 0xA7);SPI_send(SPI_DATA, 0x06);SPI_send(SPI_DATA, 0x0D);SPI_send(SPI_DATA, 0x51);SPI_send(SPI_DATA, 0x56);SPI_send(SPI_DATA, 0x18);SPI_send(SPI_DATA, 0x56);SPI_send(SPI_DATA, 0x17);SPI_send(SPI_DATA, 0x89);SPI_send(SPI_DATA, 0x11);SPI_send(SPI_DATA, 0x00);SPI_send(SPI_DATA, 0x40);SPI_send(SPI_DATA, 0x42);SPI_send(SPI_DATA, 0xC1);SPI_send(SPI_DATA, 0x4B);SPI_send(SPI_DATA, 0xA7);SPI_send(SPI_DATA, 0x06);SPI_send(SPI_DATA, 0x0D);SPI_send(SPI_DATA, 0x51);SPI_send(SPI_DATA, 0x56);SPI_send(SPI_DATA, 0x18);SPI_send(SPI_DATA, 0x56);SPI_send(SPI_DATA, 0x17);SPI_send(SPI_DATA, 0x89);SPI_send(SPI_DATA, 0x11);mdelay(5);SPI_send(SPI_CMD, 0x29);}static int __init spi_lcd_init(void){PLOG("Register lcd spi control.\n");SPI_init();tcc_set_cs_data(0);ndelay(20);set_value();tcc_set_cs_data(1);return 0;}static void __exit spi_lcd_exit(void){printk(KERN_INFO "unregister lcd spi control.\n");}module_init(spi_lcd_init);module_exit(spi_lcd_exit);MODULE_LICENSE("GPL");MODULE_AUTHOR("J.H.Luo<sparkle-cliz@>");MODULE_VERSION("0.1");MODULE_DESCRIPTION("lcd spi control driver");四，测试结果，insmod此驱动模块之后，LCD显示出开机LOGO了，说明SPI控制成功。
