在E8卡上通過linux的spi驅動讀寫高通字庫芯片。

spi是分主從的，字庫芯片不會主動通過spi發送數據。只有在linux上發起讀操作的時候，字庫才會把他的數據發送出來。

/*
* spi mode
*/
ret = ioctl(fd, SPI_IOC_WR_MODE, &mode);
if (ret == -1)
printf("can't set spi mode");


ret = ioctl(fd, SPI_IOC_RD_MODE, &mode);
if (ret == -1)
printf("can't get spi mode");


/*
* bits per word
*/
ret = ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits);
if (ret == -1)
printf("can't set bits per word");


ret = ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits);
if (ret == -1)
printf("can't get bits per word");


/*
* max speed hz
*/
ret = ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed);
if (ret == -1)
printf("can't set max speed hz");


ret = ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed);
if (ret == -1)
printf("can't get max speed hz");


printf("spi mode: %d\n", mode);
printf("bits per word: %d\n", bits);
printf("max speed: %d Hz (%d KHz)\n", speed, speed/1000);

? ?

? ? ?//spi 發送緩沖區

unsigned char tx[1024] = {0}; ?

//spi 接收緩沖區
unsigned char tx2[1024] = {0};

//字庫芯片讀命令
tx[0] = 0x03;

//3個字節的地址數據
tx[1] = (unsigned char)((address&0xff0000)>>16);?
tx[2] = (unsigned char)((address&0xff00)>>8);?
tx[3] = (unsigned char)(address&0xFF);?
struct spi_ioc_transfer tr = {
.tx_buf = (unsigned long)tx, ?//發送緩沖區
.rx_buf = (unsigned long)tx2,// 接收緩沖區
.len = 4+buflen, ?//buflen 是字庫數據的長度，由于在發送前4個字節時，字庫芯片是不往主機發送數據。如果想讀取buflen長度的字庫數據，主機必須再發送長度為buflen的任意數據，

.delay_usecs = delay,?
.speed_hz = speed,
.bits_per_word = bits,
};


ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
接收到的字庫數據，就在tx2中。

總結

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