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spi: Add spi_write_then_read

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Add support for SPI synchronous write followed by read,
this is common interface call from spi-nor to spi drivers.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Tested-by: Adam Ford <aford173@gmail.com> #da850-evm
This commit is contained in:
Jagan Teki 2019-07-22 17:22:56 +05:30
parent 6bd6c21693
commit 8473b32127
2 changed files with 44 additions and 0 deletions
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24
drivers/spi/spi-uclass.c
View File

@ -108,6 +108,30 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
return dm_spi_xfer(slave->dev, bitlen, dout, din, flags);
}
int spi_write_then_read(struct spi_slave *slave, const u8 *opcode,
size_t n_opcode, const u8 *txbuf, u8 *rxbuf,
size_t n_buf)
{
unsigned long flags = SPI_XFER_BEGIN;
int ret;
if (n_buf == 0)
flags |= SPI_XFER_END;
ret = spi_xfer(slave, n_opcode * 8, opcode, NULL, flags);
if (ret) {
debug("spi: failed to send command (%zu bytes): %d\n",
n_opcode, ret);
} else if (n_buf != 0) {
ret = spi_xfer(slave, n_buf * 8, txbuf, rxbuf, SPI_XFER_END);
if (ret)
debug("spi: failed to transfer %zu bytes of data: %d\n",
n_buf, ret);
}
return ret;
}
#if !CONFIG_IS_ENABLED(OF_PLATDATA)
static int spi_child_post_bind(struct udevice *dev)
{

20
include/spi.h
View File

@ -248,6 +248,26 @@ int spi_set_wordlen(struct spi_slave *slave, unsigned int wordlen);
int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
void *din, unsigned long flags);
/**
* spi_write_then_read - SPI synchronous write followed by read
*
* This performs a half duplex transaction in which the first transaction
* is to send the opcode and if the length of buf is non-zero then it start
* the second transaction as tx or rx based on the need from respective slave.
*
* @slave: The SPI slave device with which opcode/data will be exchanged
* @opcode: opcode used for specific transfer
* @n_opcode: size of opcode, in bytes
* @txbuf: buffer into which data to be written
* @rxbuf: buffer into which data will be read
* @n_buf: size of buf (whether it's [tx|rx]buf), in bytes
*
* Returns: 0 on success, not 0 on failure
*/
int spi_write_then_read(struct spi_slave *slave, const u8 *opcode,
size_t n_opcode, const u8 *txbuf, u8 *rxbuf,
size_t n_buf);
/* Copy memory mapped data */
void spi_flash_copy_mmap(void *data, void *offset, size_t len);