[U-Boot] [PATCH 06/20] tegra: spi: Drop the claim_bus() method to correct delays

Simon Glass
2015-02-17T22:29:40Z

At present the driver does not properly honour the requested SPI CS
deactivation delay since the SPI bus is changed in the claim_bus() method.

Everything the claim_bus() method does can be done when the device is probed
(setting the speed and mode) and at the start of a new transfer (where the
fifo_status is already cleared). So drop this method.

Also, until the delay is complete, we should not touch the bus, so make sure
that spi_cs_activate() is called before other things are done in the xfer()
method.

Signed-off-by: Simon Glass <sjg@chromium.org>
---

drivers/spi/tegra114_spi.c | 39 ++++++++-------------------------------
1 file changed, 8 insertions(+), 31 deletions(-)

diff --git a/drivers/spi/tegra114_spi.c b/drivers/spi/tegra114_spi.c
index 53ff9ea..a73c6b0 100644
--- a/drivers/spi/tegra114_spi.c
+++ b/drivers/spi/tegra114_spi.c
@@ -150,34 +150,12 @@ static int tegra114_spi_probe(struct udevice *bus)
priv->freq = plat->frequency;
priv->periph_id = plat->periph_id;

- return 0;
-}
-
-static int tegra114_spi_claim_bus(struct udevice *bus)
-{
- struct tegra114_spi_priv *priv = dev_get_priv(bus);
- struct spi_regs *regs = priv->regs;
-
/* Change SPI clock to correct frequency, PLLP_OUT0 source */
- clock_start_periph_pll(priv->periph_id, CLOCK_ID_PERIPH, priv->freq);
-
- /* Clear stale status here */
- setbits_le32(&regs->fifo_status,
- SPI_FIFO_STS_ERR |
- SPI_FIFO_STS_TX_FIFO_OVF |
- SPI_FIFO_STS_TX_FIFO_UNR |
- SPI_FIFO_STS_RX_FIFO_OVF |
- SPI_FIFO_STS_RX_FIFO_UNR |
- SPI_FIFO_STS_TX_FIFO_FULL |
- SPI_FIFO_STS_TX_FIFO_EMPTY |
- SPI_FIFO_STS_RX_FIFO_FULL |
- SPI_FIFO_STS_RX_FIFO_EMPTY);
- debug("%s: FIFO STATUS = %08x\n", __func__, readl(&regs->fifo_status));
-
- /* Set master mode and sw controlled CS */
- setbits_le32(&regs->command1, SPI_CMD1_M_S | SPI_CMD1_CS_SW_HW |
- (priv->mode << SPI_CMD1_MODE_SHIFT));
- debug("%s: COMMAND1 = %08x\n", __func__, readl(&regs->command1));
+ clock_start_periph_pll(priv->periph_id, CLOCK_ID_PERIPH,
+ priv->freq);
+
+ setbits_le32(&priv->regs->command1, SPI_CMD1_M_S | SPI_CMD1_CS_SW_HW |
+ (priv->mode << SPI_CMD1_MODE_SHIFT) | SPI_CMD1_CS_SW_VAL);

return 0;
}
@@ -248,6 +226,9 @@ static int tegra114_spi_xfer(struct udevice *dev, unsigned int bitlen,

ret = 0;

+ if (flags & SPI_XFER_BEGIN)
+ spi_cs_activate(dev);
+
/* clear all error status bits */
reg = readl(&regs->fifo_status);
writel(reg, &regs->fifo_status);
@@ -259,9 +240,6 @@ static int tegra114_spi_xfer(struct udevice *dev, unsigned int bitlen,
/* set xfer size to 1 block (32 bits) */
writel(0, &regs->dma_blk);

- if (flags & SPI_XFER_BEGIN)
- spi_cs_activate(dev);
-
/* handle data in 32-bit chunks */
while (num_bytes > 0) {
int bytes;
@@ -384,7 +362,6 @@ static int tegra114_spi_set_mode(struct udevice *bus, uint mode)
}

static const struct dm_spi_ops tegra114_spi_ops = {
- .claim_bus = tegra114_spi_claim_bus,
.xfer = tegra114_spi_xfer,
.set_speed = tegra114_spi_set_speed,
.set_mode = tegra114_spi_set_mode,
--
2.2.0.rc0.207.ga3a616c