[PATCH 1/2] spi: spi-mem: Add the spi_set_xfer_bpw function

From: Chuanhua Han
Date: Fri Sep 21 2018 - 03:06:18 EST


Before we add this spi_transfer to the spi_message chain table, we need
bits_per_word_mask based on spi_control to set the bits_per_word of
this spi_transfer.

Signed-off-by: Chuanhua Han <chuanhua.han@xxxxxxx>
---
drivers/spi/spi-mem.c | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)

diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
index eb72dba71d83..717e711c0952 100644
--- a/drivers/spi/spi-mem.c
+++ b/drivers/spi/spi-mem.c
@@ -175,6 +175,41 @@ bool spi_mem_supports_op(struct spi_mem *mem, const struct spi_mem_op *op)
}
EXPORT_SYMBOL_GPL(spi_mem_supports_op);

+/**
+ * spi_set_xfer_bpw() - Set the bits_per_word for each transfer based on
+ * the bits_per_word_mask of the spi controller
+ * @ctrl: the spi controller
+ * @xfer: the spi transfer
+ *
+ * This function sets the bits_per_word for each transfer based on the spi
+ * controller's bits_per_word_mask to improve the efficiency of spi transport.
+ *
+ * Return: 0 in case of success, a negative error code otherwise.
+ */
+int spi_set_xfer_bpw(struct spi_controller *ctlr, struct spi_transfer *xfer)
+{
+ if (!ctlr || !xfer) {
+ dev_err(&ctlr->dev,
+ "Fail to set bits_per_word for spi transfer\n");
+ return -EINVAL;
+ }
+
+ if (ctlr->bits_per_word_mask) {
+ if (!(xfer->len % 4)) {
+ if (ctlr->bits_per_word_mask & SPI_BPW_MASK(32))
+ xfer->bits_per_word = 32;
+ } else if (!(xfer->len % 2)) {
+ if (ctlr->bits_per_word_mask & SPI_BPW_MASK(16))
+ xfer->bits_per_word = 16;
+ } else {
+ xfer->bits_per_word = 8;
+ }
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(spi_set_xfer_bpw);
+
/**
* spi_mem_exec_op() - Execute a memory operation
* @mem: the SPI memory
@@ -252,6 +287,7 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
xfers[xferpos].tx_buf = tmpbuf;
xfers[xferpos].len = sizeof(op->cmd.opcode);
xfers[xferpos].tx_nbits = op->cmd.buswidth;
+ spi_set_xfer_bpw(ctlr, &xfers[xferpos]);
spi_message_add_tail(&xfers[xferpos], &msg);
xferpos++;
totalxferlen++;
@@ -266,6 +302,7 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
xfers[xferpos].tx_buf = tmpbuf + 1;
xfers[xferpos].len = op->addr.nbytes;
xfers[xferpos].tx_nbits = op->addr.buswidth;
+ spi_set_xfer_bpw(ctlr, &xfers[xferpos]);
spi_message_add_tail(&xfers[xferpos], &msg);
xferpos++;
totalxferlen += op->addr.nbytes;
@@ -276,6 +313,7 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
xfers[xferpos].len = op->dummy.nbytes;
xfers[xferpos].tx_nbits = op->dummy.buswidth;
+ spi_set_xfer_bpw(ctlr, &xfers[xferpos]);
spi_message_add_tail(&xfers[xferpos], &msg);
xferpos++;
totalxferlen += op->dummy.nbytes;
@@ -291,6 +329,7 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
}

xfers[xferpos].len = op->data.nbytes;
+ spi_set_xfer_bpw(ctlr, &xfers[xferpos]);
spi_message_add_tail(&xfers[xferpos], &msg);
xferpos++;
totalxferlen += op->data.nbytes;
--
2.17.1