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楼主 #1 2017-12-11 17:57:05

晕哥
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荔枝派全志Allwinner V3s的u-boot spl里面使用默认的spi速度,我试着修改spi 速度,看能否成功。

荔枝派全志Allwinner V3s的u-boot spl里面使用默认的spi速度,我试着修改spi 速度,看能否成功。
参考: 荔枝派Zero V3s开发板入坑教程

#include <asm/arch/spi.h>

#define SUNXI_SPI_MAX_RATE (108 * 1000 * 1000)
#define SUNXI_SPI_MIN_RATE (3 * 1000)
static int spi0_set_speed(uint speed)
{
	unsigned int div;
	uint32_t reg;

	printf("|||||||||| %s: speed=%u\n", __func__, speed);

	speed = min(speed, (unsigned int)SUNXI_SPI_MAX_RATE);
	speed = max((unsigned int)SUNXI_SPI_MIN_RATE, speed);

	div = SUNXI_SPI_MAX_RATE / (2 * speed);

	if (div <= (SUNXI_SPI_CLK_CTL_CDR2_MASK + 1)) {
		if (div > 0)
			div--;

		reg = SUNXI_SPI_CLK_CTL_CDR2(div) | SUNXI_SPI_CLK_CTL_DRS;
	} else {
		div = __ilog2(SUNXI_SPI_MAX_RATE) - __ilog2(speed);
		reg = SUNXI_SPI_CLK_CTL_CDR1(div);
	}

	writel(reg, SUN6I_SPI0_CCTL);

	printf("//////////// %s: speed=%u\n", __func__, speed);
	printf("//////////// %s: speed=%u\n", __func__, speed);
	printf("//////////// %s: speed=%u\n", __func__, speed);

	return 0;
}

调用

	spi0_enable_clock();
	spi0_set_speed(98000000);




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