[讨论]

gpio模拟I2C

2015-2-2 15:25:36 5556

0 开发中经常与i2c打交道，芯片中自带的硬件i2c控制器使用起来并不是很灵活，而且要研究半天的寄存器。所以干脆搞一个软件模拟gpio的通用代码，移植起来也方便，使用灵活具体代码如下： #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "gpio_i2c.h" #include "../ralink_gpio.h" #define DELAY(u) udelay(u100) #define RT2860REG(addr) ((volatile u32 )(addr)) static void gpio_i2c_set_bit(int id, int onoff) { int tmp; if(id<=21&&id>=0) { tmp = le32_to_cpu((volatile u32 )(RALINK_REG_PIODIR)); tmp \|= (1<<(id)); (volatile u32 )(RALINK_REG_PIODIR) = tmp; tmp = le32_to_cpu((volatile u32 )(RALINK_REG_PIODATA)); tmp = (tmp&~(1<<(id)))\|(onoff<<(id)); (volatile u32 )(RALINK_REG_PIODATA) = tmp; } else if(id>=22&&id<=27) { tmp = le32_to_cpu((volatile u32 )(RALINK_REG_PIO2722DIR)); tmp \|= (1<<(id-22)); (volatile u32 )(RALINK_REG_PIO2722DIR) = tmp; tmp = le32_to_cpu((volatile u32 )(RALINK_REG_PIO2722DATA)); tmp = (tmp&~(1<<(id-22)))\|(onoff<<(id-22)); (volatile u32 )(RALINK_REG_PIO2722DATA) = tmp; } else { printk("####HU#### %s id %d invalid rn",__FUNCTION__,id); } } static int gpio_i2c_get_bit(int id) { int tmp; if(id<=21&&id>=0) { tmp = le32_to_cpu((volatile u32 )(RALINK_REG_PIODIR)); tmp &= ~(1<<(id)); (volatile u32 )(RALINK_REG_PIODIR) = tmp; tmp = le32_to_cpu((volatile u32 )(RALINK_REG_PIODATA)); return (tmp>>id&0x01); } else if(id>=22&&id<=27) { tmp = le32_to_cpu((volatile u32 )(RALINK_REG_PIO2722DIR)); tmp &= ~(1<<(id-22)); (volatile u32 )(RALINK_REG_PIO2722DIR) = tmp; tmp = le32_to_cpu((volatile u32 )(RALINK_REG_PIO2722DATA)); return (tmp>>(id-22)&0x01); } else { printk("####HU#### %s id %d invalid rn",__FUNCTION__,id); } } static void i2c_clk(int onoff) { gpio_i2c_set_bit(2,onoff); } static void i2c_dat(int onoff) { gpio_i2c_set_bit(1,onoff); } static unsigned char i2c_data_read(void) { // unsigned char tmp; // tmp = le32_to_cpu((volatile u32 )(RALINK_REG_PIODIR)); // tmp &= ~(1<<(1)); // (volatile u32 )(RALINK_REG_PIODIR) = tmp; // // //DELAY(1); // // tmp = le32_to_cpu((volatile u32 )(RALINK_REG_PIODATA)); // if((tmp&(1<<1)) != 0) // return 1; // else // return 0; return gpio_i2c_get_bit(1); } / * sends a start bit via I2C rountine. * / static void i2c_start_bit(void) { DELAY(1); i2c_clk(1); i2c_dat(1); DELAY(1); i2c_dat(0); DELAY(1); } / * sends a stop bit via I2C rountine. * / static void i2c_stop_bit(void) { i2c_clk(0); i2c_dat(1); DELAY(1); i2c_clk(1); } / * sends a character over I2C rountine. * * @param c: character to send * / static void i2c_send_byte(unsigned char c) { int i; local_irq_disable(); //i2c_clk(1); for (i=0; i<8; i++) { i2c_clk(0); if (c & (1<<(7-i))) i2c_dat(1); else i2c_dat(0); DELAY(1); i2c_clk(1); DELAY(1); } // i2c_dat(1); local_irq_enable(); } / receives a character from I2C rountine. * * [url=home.php?mod=space&uid=1141835]@Return[/url] value: character received * / static unsigned char i2c_receive_byte(void) { int j=0; int i; unsigned char regvalue; local_irq_disable(); i2c_data_read(); for (i=0; i<8; i++) { i2c_clk(0); DELAY(1); i2c_clk(1); i2c_data_read(); if (i2c_data_read()) j+=(1<<(7-i)); DELAY(1); } local_irq_enable(); // i2c_dat(0); // DELAY(1); return j; } / receives an acknowledge from I2C rountine. * * @return value: 0--Ack received; 1--Nack received * / static int i2c_receive_ack(void) { int nack; i2c_data_read(); i2c_clk(0); DELAY(1); i2c_clk(1); i2c_data_read(); nack = i2c_data_read(); DELAY(1); i2c_dat(1); if (nack == 0) return 1; return 0; } / * sends an acknowledge over I2C rountine. * / static void i2c_send_ack(void) { i2c_clk(0); i2c_dat(0); DELAY(1); i2c_clk(1); DELAY(1); } static void si2c_init() { RT2860REG(RALINK_REG_GPIOMODE)=RT2860REG(RALINK_REG_GPIOMODE)\|(1<<0); } static void si2c_exit() { } / * read data from the I2C bus by GPIO simulated of a device rountine. * * @param devaddress: address of the device * @param address: address of register within device * * @return value: data from the device readed * / unsigned char gpio_i2c_read(unsigned char devaddress, unsigned char address) { int rxdata; si2c_init(); i2c_start_bit(); i2c_send_byte((unsigned char)((devaddress<<1)\|0)); i2c_receive_ack(); i2c_send_byte(address); i2c_receive_ack(); i2c_start_bit(); i2c_send_byte((unsigned char)((devaddress<<1)\|1)); i2c_receive_ack(); rxdata = i2c_receive_byte(); i2c_send_ack(); i2c_stop_bit(); si2c_exit(); return rxdata; } EXPORT_SYMBOL(gpio_i2c_read); / * writes data to a device on the I2C bus rountine. * * @param devaddress: address of the device * @param address: address of register within device * @param data: data for write to device * / void gpio_i2c_write(unsigned char devaddress, unsigned char address, unsigned char data) { si2c_init(); i2c_start_bit(); i2c_send_byte((unsigned char)((devaddress<<1)\|0)); i2c_receive_ack(); i2c_send_byte(address); i2c_receive_ack(); i2c_send_byte(data); i2c_receive_ack(); i2c_stop_bit(); si2c_exit(); } EXPORT_SYMBOL(gpio_i2c_write); / * initializes I2C interface routine. * * @return value:0--success; 1--error. * / static int __init gpio_i2c_init(void) { } static void __exit gpio_i2c_exit(void) { } module_init(gpio_i2c_init); module_exit(gpio_i2c_exit); #ifdef MODULE #include #endif MODULE_INFO(build, UTS_VERSION); MODULE_LICENSE("GPL"); MODULE_VERSION("HI_VERSION=" OSDRV_MODULE_VERSION_STRING); 复制代码* gpio_i2c_set_bit与gpio_i2c_get_bit设置gpio高低的，DELAY宏为延时方法，理论只要实现这几个值就能够实现标准的gpio_i2c的功能了 1
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