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Subject[PATCH 09/11] spi: dw: prepare the transfer routine for enhanced mode
Date
The transfer routine of dual/quad/octal is similar to standard SPI mode
except that we do not need to worry about CS being de-asserted and we
will be writing the address to a single FIFO location.

Signed-off-by: Sudip Mukherjee <sudip.mukherjee@sifive.com>
---
drivers/spi/spi-dw-core.c | 141 +++++++++++++++++++++++++++++++++-----
1 file changed, 125 insertions(+), 16 deletions(-)

diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
index 2564a2276572..d6afa75e7023 100644
--- a/drivers/spi/spi-dw-core.c
+++ b/drivers/spi/spi-dw-core.c
@@ -712,6 +712,28 @@ static int dw_spi_wait_mem_op_done(struct dw_spi *dws)
return 0;
}

+static void ext_transfer_delay(struct dw_spi *dws)
+{
+ struct spi_delay delay;
+ unsigned long ns, us;
+ u32 nents;
+
+ nents = dw_readl(dws, DW_SPI_TXFLR);
+ ns = NSEC_PER_SEC / dws->current_freq * nents;
+ ns *= dws->n_bytes * BITS_PER_BYTE;
+ if (ns <= NSEC_PER_USEC) {
+ delay.unit = SPI_DELAY_UNIT_NSECS;
+ delay.value = ns;
+ } else {
+ us = DIV_ROUND_UP(ns, NSEC_PER_USEC);
+ delay.unit = SPI_DELAY_UNIT_USECS;
+ delay.value = clamp_val(us, 0, USHRT_MAX);
+ }
+ /* wait until there is some space in TX FIFO */
+ while (!(dw_readl(dws, DW_SPI_SR) & DW_SPI_SR_TF_NOT_FULL))
+ spi_delay_exec(&delay, NULL);
+}
+
static void dw_spi_stop_mem_op(struct dw_spi *dws, struct spi_device *spi)
{
dw_spi_enable_chip(dws, 0);
@@ -719,6 +741,82 @@ static void dw_spi_stop_mem_op(struct dw_spi *dws, struct spi_device *spi)
dw_spi_enable_chip(dws, 1);
}

+static int enhanced_transfer(struct dw_spi *dws, struct spi_device *spi,
+ const struct spi_mem_op *op)
+{
+ u32 max, txw = 0, rxw;
+ bool cs_done = false;
+ void *buf = dws->tx;
+ int ret;
+
+ /* Send cmd as 32 bit value */
+ if (buf) {
+ txw = *(u32 *)(buf);
+ dw_write_io_reg(dws, DW_SPI_DR, txw);
+ buf += 4;
+ dws->tx_len--;
+ if (op->addr.nbytes) {
+ /*
+ * Send address as 32 bit value if address
+ * is present in the instruction.
+ */
+ txw = *(u32 *)(buf);
+ dw_write_io_reg(dws, DW_SPI_DR, txw);
+ buf += 4;
+ dws->tx_len--;
+ }
+ }
+
+ do {
+ max = min_t(u32, dws->tx_len, dws->fifo_len -
+ dw_readl(dws, DW_SPI_TXFLR));
+ while (max--) {
+ if (buf) {
+ txw = *(u8 *)(buf);
+ buf += dws->n_bytes;
+ }
+ dw_write_io_reg(dws, DW_SPI_DR, txw);
+ --dws->tx_len;
+ }
+ /* Enable CS after filling up FIFO */
+ if (!cs_done) {
+ dw_spi_set_cs(spi, false);
+ cs_done = true;
+ }
+ ext_transfer_delay(dws);
+ if (!dws->tx_len && !dws->rx_len) {
+ /*
+ * We only need to wait for done if there is
+ * nothing to receive and there is nothing more
+ * to transmit. If we are receiving, then the
+ * wait cycles will make sure we wait.
+ */
+ ret = dw_spi_wait_mem_op_done(dws);
+ if (ret)
+ return ret;
+ }
+ } while (dws->tx_len);
+
+ buf = dws->rx;
+ while (dws->rx_len) {
+ max = dw_spi_rx_max(dws);
+
+ while (max--) {
+ rxw = dw_read_io_reg(dws, DW_SPI_DR);
+ if (buf) {
+ *(u8 *)(buf) = rxw;
+ buf += dws->n_bytes;
+ }
+ --dws->rx_len;
+ }
+
+ ret = dw_spi_check_status(dws, true);
+ if (ret)
+ return ret;
+ }
+ return 0;
+}
+
static void update_spi_ctrl0(struct dw_spi *dws, const struct spi_mem_op *op, bool enable)
{
u32 spi_ctrlr0;
@@ -846,25 +944,36 @@ static int dw_spi_exec_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
* manually restricting the SPI bus frequency using the
* dws->max_mem_freq parameter.
*/
- local_irq_save(flags);
- preempt_disable();
+ if (!enhanced_spi) {
+ local_irq_save(flags);
+ preempt_disable();

- ret = dw_spi_write_then_read(dws, mem->spi);
+ ret = dw_spi_write_then_read(dws, mem->spi);

- local_irq_restore(flags);
- preempt_enable();
+ local_irq_restore(flags);
+ preempt_enable();

- /*
- * Wait for the operation being finished and check the controller
- * status only if there hasn't been any run-time error detected. In the
- * former case it's just pointless. In the later one to prevent an
- * additional error message printing since any hw error flag being set
- * would be due to an error detected on the data transfer.
- */
- if (!ret) {
- ret = dw_spi_wait_mem_op_done(dws);
- if (!ret)
- ret = dw_spi_check_status(dws, true);
+ /*
+ * Wait for the operation being finished and check the
+ * controller status only if there hasn't been any
+ * run-time error detected. In the former case it's
+ * just pointless. In the later one to prevent an
+ * additional error message printing since any hw error
+ * flag being set would be due to an error detected on
+ * the data transfer.
+ */
+ if (!ret) {
+ ret = dw_spi_wait_mem_op_done(dws);
+ if (!ret)
+ ret = dw_spi_check_status(dws, true);
+ }
+ } else {
+ /*
+ * We donot need to disable IRQs as clock stretching will
+ * be enabled in enhanced mode which will prevent CS
+ * from being de-assert.
+ */
+ ret = enhanced_transfer(dws, mem->spi, op);
}

dw_spi_stop_mem_op(dws, mem->spi);
--
2.30.2
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