The designware ssi device has "broken" chip select behaviour [1], and needs specific manipulation to use the built-in chip select. The existing fix is to use an external GPIO for chip select, but typically the K210 has SPI3 directly connected to a flash chip with dedicated pins. This makes it impossible to use the spi_xfer function to use spi, since the CS is de-asserted in between calls. This patch adds an implementation of exec_op, which gives correct behaviour when reading/writing spi flash.
[1] https://lkml.org/lkml/2015/12/23/132
Signed-off-by: Sean Anderson seanga2@gmail.com --- This patch was previously part of https://patchwork.ozlabs.org/project/uboot/list/?series=161576
Changes in v2: - Add external gpio cs support - Clean up exec_op - Convert debug to log_* - Limit data transfers to 64k
drivers/spi/designware_spi.c | 104 +++++++++++++++++++++++++++++++++++ 1 file changed, 104 insertions(+)
diff --git a/drivers/spi/designware_spi.c b/drivers/spi/designware_spi.c index d9dc739d7d..62c0bda4cc 100644 --- a/drivers/spi/designware_spi.c +++ b/drivers/spi/designware_spi.c @@ -19,6 +19,7 @@ #include <errno.h> #include <malloc.h> #include <spi.h> +#include <spi-mem.h> #include <fdtdec.h> #include <reset.h> #include <dm/device_compat.h> @@ -581,6 +582,108 @@ static int dw_spi_xfer(struct udevice *dev, unsigned int bitlen, return ret; }
+/* + * This function is necessary for reading SPI flash with the native CS + * c.f. https://lkml.org/lkml/2015/12/23/132 + */ +static int dw_spi_exec_op(struct spi_slave *slave, const struct spi_mem_op *op) +{ + bool read = op->data.dir == SPI_MEM_DATA_IN; + int pos, i, ret = 0; + struct udevice *bus = slave->dev->parent; + struct dw_spi_priv *priv = dev_get_priv(bus); + u8 op_len = sizeof(op->cmd.opcode) + op->addr.nbytes + op->dummy.nbytes; + u8 op_buf[op_len]; + u32 cr0; + + if (read) + priv->tmode = CTRLR0_TMOD_EPROMREAD; + else + priv->tmode = CTRLR0_TMOD_TO; + + log_debug("buf=%p len=%u [bytes]\n", op->data.buf.in, op->data.nbytes); + + cr0 = priv->update_cr0(priv); + log_debug("cr0=%08x\n", cr0); + + spi_enable_chip(priv, 0); + dw_write(priv, DW_SPI_CTRL0, cr0); + if (read) + dw_write(priv, DW_SPI_CTRL1, op->data.nbytes - 1); + spi_enable_chip(priv, 1); + + /* From spi_mem_exec_op */ + pos = 0; + op_buf[pos++] = op->cmd.opcode; + if (op->addr.nbytes) { + for (i = 0; i < op->addr.nbytes; i++) + op_buf[pos + i] = op->addr.val >> + (8 * (op->addr.nbytes - i - 1)); + + pos += op->addr.nbytes; + } + if (op->dummy.nbytes) + memset(op_buf + pos, 0xff, op->dummy.nbytes); + + external_cs_manage(slave->dev, false); + + priv->tx = &op_buf; + priv->tx_end = priv->tx + op_len; + priv->rx = NULL; + priv->rx_end = NULL; + while (priv->tx != priv->tx_end) + dw_writer(priv); + + /* + * XXX: The following are tight loops! Enabling debug messages may cause + * them to fail because we are not reading/writing the fifo fast enough. + */ + if (read) { + priv->rx = op->data.buf.in; + priv->rx_end = priv->rx + op->data.nbytes; + + dw_write(priv, DW_SPI_SER, 1 << spi_chip_select(slave->dev)); + while (priv->rx != priv->rx_end) + dw_reader(priv); + } else { + u32 val; + + priv->tx = op->data.buf.out; + priv->tx_end = priv->tx + op->data.nbytes; + + /* Fill up the write fifo before starting the transfer */ + dw_writer(priv); + dw_write(priv, DW_SPI_SER, 1 << spi_chip_select(slave->dev)); + while (priv->tx != priv->tx_end) + dw_writer(priv); + + if (readl_poll_timeout(priv->regs + DW_SPI_SR, val, + (val & SR_TF_EMPT) && !(val & SR_BUSY), + RX_TIMEOUT * 1000)) { + ret = -ETIMEDOUT; + } + } + + dw_write(priv, DW_SPI_SER, 0); + external_cs_manage(slave->dev, true); + + log_debug("%u bytes xfered\n", op->data.nbytes); + return ret; +} + +/* The size of ctrl1 limits data transfers to 64K */ +static int dw_spi_adjust_op_size(struct spi_slave *slave, struct spi_mem_op *op) +{ + op->data.nbytes = min(op->data.nbytes, (unsigned int)SZ_64K); + + return 0; +} + +static const struct spi_controller_mem_ops dw_spi_mem_ops = { + .exec_op = dw_spi_exec_op, + .adjust_op_size = dw_spi_adjust_op_size, +}; + static int dw_spi_set_speed(struct udevice *bus, uint speed) { struct dw_spi_platdata *plat = dev_get_platdata(bus); @@ -646,6 +749,7 @@ static int dw_spi_remove(struct udevice *bus)
static const struct dm_spi_ops dw_spi_ops = { .xfer = dw_spi_xfer, + .mem_ops = &dw_spi_mem_ops, .set_speed = dw_spi_set_speed, .set_mode = dw_spi_set_mode, /*