spi: spi-mem: Add an ecc parameter to the spi_mem_op structure

Soon the SPI-NAND core will need a way to request a SPI controller to
enable ECC support for a given operation. This is because of the
pipelined integration of certain ECC engines, which are directly managed
by the SPI controller itself.

Introduce a spi_mem_op additional field for this purpose: ecc.

So far this field is left unset and checked to be false by all
the SPI controller drivers in their ->supports_op() hook, as they all
call spi_mem_default_supports_op().

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Pratyush Yadav <p.yadav@ti.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/linux-mtd/20220127091808.1043392-7-miquel.raynal@bootlin.com

drivers/spi/spi-mem.c

@@ -178,6 +178,11 @@ bool spi_mem_default_supports_op(struct spi_mem *mem,
 			return false;
 	}
 
+	if (op->data.ecc) {
+		if (!spi_mem_controller_is_capable(ctlr, ecc))
+			return false;
+	}
+
 	return spi_mem_check_buswidth(mem, op);
 }
 EXPORT_SYMBOL_GPL(spi_mem_default_supports_op);

include/linux/spi/spi-mem.h

@@ -89,6 +89,7 @@ enum spi_mem_data_dir {
  * @dummy.dtr: whether the dummy bytes should be sent in DTR mode or not
  * @data.buswidth: number of IO lanes used to send/receive the data
  * @data.dtr: whether the data should be sent in DTR mode or not
+ * @data.ecc: whether error correction is required or not
  * @data.dir: direction of the transfer
  * @data.nbytes: number of data bytes to send/receive. Can be zero if the
  *		 operation does not involve transferring data
@@ -119,6 +120,7 @@ struct spi_mem_op {
 	struct {
 		u8 buswidth;
 		u8 dtr : 1;
+		u8 ecc : 1;
 		enum spi_mem_data_dir dir;
 		unsigned int nbytes;
 		union {
@@ -288,9 +290,11 @@ struct spi_controller_mem_ops {
 /**
  * struct spi_controller_mem_caps - SPI memory controller capabilities
  * @dtr: Supports DTR operations
+ * @ecc: Supports operations with error correction
  */
 struct spi_controller_mem_caps {
 	bool dtr;
+	bool ecc;
 };
 
 #define spi_mem_controller_is_capable(ctlr, cap)	\