static int sun4i_spi_set_speed(struct udevice *dev, uint speed)
{
	struct sun4i_spi_platdata *plat = dev_get_platdata(dev);
	struct sun4i_spi_priv *priv = dev_get_priv(dev);
	unsigned int div;
	u32 reg;

	if (speed > plat->max_hz)
		speed = plat->max_hz;

	if (speed < SUN4I_SPI_MIN_RATE)
		speed = SUN4I_SPI_MIN_RATE;
	/*
	 * Setup clock divider.
	 *
	 * We have two choices there. Either we can use the clock
	 * divide rate 1, which is calculated thanks to this formula:
	 * SPI_CLK = MOD_CLK / (2 ^ (cdr + 1))
	 * Or we can use CDR2, which is calculated with the formula:
	 * SPI_CLK = MOD_CLK / (2 * (cdr + 1))
	 * Whether we use the former or the latter is set through the
	 * DRS bit.
	 *
	 * First try CDR2, and if we can't reach the expected
	 * frequency, fall back to CDR1.
	 */

	div = SUN4I_SPI_MAX_RATE / (2 * speed);
	reg = readl(&priv->regs->cctl);

	if (div <= (SUN4I_CLK_CTL_CDR2_MASK + 1)) {
		if (div > 0)
			div--;

		reg &= ~(SUN4I_CLK_CTL_CDR2_MASK | SUN4I_CLK_CTL_DRS);
		reg |= SUN4I_CLK_CTL_CDR2(div) | SUN4I_CLK_CTL_DRS;
	} else {
		div = __ilog2(SUN4I_SPI_MAX_RATE) - __ilog2(speed);
		reg &= ~((SUN4I_CLK_CTL_CDR1_MASK << 8) | SUN4I_CLK_CTL_DRS);
		reg |= SUN4I_CLK_CTL_CDR1(div);
	}

	priv->freq = speed;
	writel(reg, &priv->regs->cctl);

	return 0;
}
示例#2
0
文件: spi-sun4i.c 项目: 7799/linux
static int sun4i_spi_transfer_one(struct spi_master *master,
				  struct spi_device *spi,
				  struct spi_transfer *tfr)
{
	struct sun4i_spi *sspi = spi_master_get_devdata(master);
	unsigned int mclk_rate, div, timeout;
	unsigned int tx_len = 0;
	int ret = 0;
	u32 reg;

	/* We don't support transfer larger than the FIFO */
	if (tfr->len > SUN4I_FIFO_DEPTH)
		return -EINVAL;

	reinit_completion(&sspi->done);
	sspi->tx_buf = tfr->tx_buf;
	sspi->rx_buf = tfr->rx_buf;
	sspi->len = tfr->len;

	/* Clear pending interrupts */
	sun4i_spi_write(sspi, SUN4I_INT_STA_REG, ~0);


	reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);

	/* Reset FIFOs */
	sun4i_spi_write(sspi, SUN4I_CTL_REG,
			reg | SUN4I_CTL_RF_RST | SUN4I_CTL_TF_RST);

	/*
	 * Setup the transfer control register: Chip Select,
	 * polarities, etc.
	 */
	if (spi->mode & SPI_CPOL)
		reg |= SUN4I_CTL_CPOL;
	else
		reg &= ~SUN4I_CTL_CPOL;

	if (spi->mode & SPI_CPHA)
		reg |= SUN4I_CTL_CPHA;
	else
		reg &= ~SUN4I_CTL_CPHA;

	if (spi->mode & SPI_LSB_FIRST)
		reg |= SUN4I_CTL_LMTF;
	else
		reg &= ~SUN4I_CTL_LMTF;


	/*
	 * If it's a TX only transfer, we don't want to fill the RX
	 * FIFO with bogus data
	 */
	if (sspi->rx_buf)
		reg &= ~SUN4I_CTL_DHB;
	else
		reg |= SUN4I_CTL_DHB;

	/* We want to control the chip select manually */
	reg |= SUN4I_CTL_CS_MANUAL;

	sun4i_spi_write(sspi, SUN4I_CTL_REG, reg);

	/* Ensure that we have a parent clock fast enough */
	mclk_rate = clk_get_rate(sspi->mclk);
	if (mclk_rate < (2 * spi->max_speed_hz)) {
		clk_set_rate(sspi->mclk, 2 * spi->max_speed_hz);
		mclk_rate = clk_get_rate(sspi->mclk);
	}

	/*
	 * Setup clock divider.
	 *
	 * We have two choices there. Either we can use the clock
	 * divide rate 1, which is calculated thanks to this formula:
	 * SPI_CLK = MOD_CLK / (2 ^ (cdr + 1))
	 * Or we can use CDR2, which is calculated with the formula:
	 * SPI_CLK = MOD_CLK / (2 * (cdr + 1))
	 * Wether we use the former or the latter is set through the
	 * DRS bit.
	 *
	 * First try CDR2, and if we can't reach the expected
	 * frequency, fall back to CDR1.
	 */
	div = mclk_rate / (2 * spi->max_speed_hz);
	if (div <= (SUN4I_CLK_CTL_CDR2_MASK + 1)) {
		if (div > 0)
			div--;

		reg = SUN4I_CLK_CTL_CDR2(div) | SUN4I_CLK_CTL_DRS;
	} else {
		div = ilog2(mclk_rate) - ilog2(spi->max_speed_hz);
		reg = SUN4I_CLK_CTL_CDR1(div);
	}

	sun4i_spi_write(sspi, SUN4I_CLK_CTL_REG, reg);

	/* Setup the transfer now... */
	if (sspi->tx_buf)
		tx_len = tfr->len;

	/* Setup the counters */
	sun4i_spi_write(sspi, SUN4I_BURST_CNT_REG, SUN4I_BURST_CNT(tfr->len));
	sun4i_spi_write(sspi, SUN4I_XMIT_CNT_REG, SUN4I_XMIT_CNT(tx_len));

	/* Fill the TX FIFO */
	sun4i_spi_fill_fifo(sspi, SUN4I_FIFO_DEPTH);

	/* Enable the interrupts */
	sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, SUN4I_INT_CTL_TC);

	/* Start the transfer */
	reg = sun4i_spi_read(sspi, SUN4I_CTL_REG);
	sun4i_spi_write(sspi, SUN4I_CTL_REG, reg | SUN4I_CTL_XCH);

	timeout = wait_for_completion_timeout(&sspi->done,
					      msecs_to_jiffies(1000));
	if (!timeout) {
		ret = -ETIMEDOUT;
		goto out;
	}

	sun4i_spi_drain_fifo(sspi, SUN4I_FIFO_DEPTH);

out:
	sun4i_spi_write(sspi, SUN4I_INT_CTL_REG, 0);

	return ret;
}