[PATCH v5 2/2] mtd: spi-nor: use spi-mem dirmap API

[Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>]

Make use of the spi-mem direct mapping API to let advanced controllers
optimize read/write operations when they support direct mapping.

Based on the original patch by Boris Brezillon
<boris.brezillon@bootlin.com>.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>

---
Changes in version 5:
- transformed *if*/return* statements into an extra check before the memcpy()
  call and removed an empty line in spi_nor_spimem_read_data();
- resolved a reject when adding the 'nbytes' local variable and refreshed
  atop of the previous patch in spi_nor_spimem_write_data();
- removed the unnecessary *if*/return* statements in
  spi_nor_spimem_write_data();
- added the 'kernel-doc' comment for the 'dirmap' field of the 'struct spi_nor';
- refreshed the patch.
 
Changes in version 4:
- moved the spi_mem_dirmap_{read|write}() calls closer to the ending of
  spi_nor_{read|write}(), adapting to the chnages caused by the new patch
  splitting spi_nor_spimem_xfer_data()...

Changes in version 3:
- simplified the way spi_mem_dirmap_{read|write}() are called;
- added Boris' tag.

Changes in version 2:
- moved the spi_mem_dirmap_{read|write}() calls from spi_nor_{read|write}() to
  spi_nor_spimem_{read|write}_data().

 drivers/mtd/spi-nor/spi-nor.c |   94 +++++++++++++++++++++++++++++++++++++-----
 include/linux/mtd/spi-nor.h   |    6 ++
 2 files changed, 90 insertions(+), 10 deletions(-)

Index: linux/drivers/mtd/spi-nor/spi-nor.c
===================================================================
--- linux.orig/drivers/mtd/spi-nor/spi-nor.c
+++ linux/drivers/mtd/spi-nor/spi-nor.c
@@ -306,6 +306,7 @@ static ssize_t spi_nor_spimem_read_data(
 			   SPI_MEM_OP_DUMMY(nor->read_dummy, 1),
 			   SPI_MEM_OP_DATA_IN(len, buf, 1));
 	bool usebouncebuf;
+	ssize_t nbytes;
 	int error;
 
 	/* get transfer protocols. */
@@ -319,14 +320,20 @@ static ssize_t spi_nor_spimem_read_data(
 
 	usebouncebuf = spi_nor_spimem_bounce(nor, &op);
 
-	error = spi_nor_spimem_exec_op(nor, &op);
-	if (error)
-		return error;
+	if (nor->dirmap.rdesc) {
+		nbytes = spi_mem_dirmap_read(nor->dirmap.rdesc, op.addr.val,
+					     op.data.nbytes, op.data.buf.in);
+	} else {
+		error = spi_nor_spimem_exec_op(nor, &op);
+		if (error)
+			return error;
+		nbytes = op.data.nbytes;
+	}
 
-	if (usebouncebuf)
-		memcpy(buf, op.data.buf.in, op.data.nbytes);
+	if (usebouncebuf && nbytes > 0)
+		memcpy(buf, op.data.buf.in, nbytes);
 
-	return op.data.nbytes;
+	return nbytes;
 }
 
 /**
@@ -365,6 +372,7 @@ static ssize_t spi_nor_spimem_write_data
 			   SPI_MEM_OP_ADDR(nor->addr_width, to, 1),
 			   SPI_MEM_OP_NO_DUMMY,
 			   SPI_MEM_OP_DATA_OUT(len, buf, 1));
+	ssize_t nbytes;
 	int error;
 
 	op.cmd.buswidth = spi_nor_get_protocol_inst_nbits(nor->write_proto);
@@ -377,11 +385,17 @@ static ssize_t spi_nor_spimem_write_data
 	if (spi_nor_spimem_bounce(nor, &op))
 		memcpy(nor->bouncebuf, buf, op.data.nbytes);
 
-	error = spi_nor_spimem_exec_op(nor, &op);
-	if (error)
-		return error;
+	if (nor->dirmap.wdesc) {
+		nbytes = spi_mem_dirmap_write(nor->dirmap.wdesc, op.addr.val,
+					      op.data.nbytes, op.data.buf.out);
+	} else {
+		error = spi_nor_spimem_exec_op(nor, &op);
+		if (error)
+			return error;
+		nbytes = op.data.nbytes;
+	}
 
-	return op.data.nbytes;
+	return nbytes;
 }
 
 /**
@@ -5265,6 +5279,58 @@ int spi_nor_scan(struct spi_nor *nor, co
 }
 EXPORT_SYMBOL_GPL(spi_nor_scan);
 
+static int spi_nor_create_read_dirmap(struct spi_nor *nor)
+{
+	struct spi_mem_dirmap_info info = {
+		.op_tmpl = SPI_MEM_OP(SPI_MEM_OP_CMD(nor->read_opcode, 1),
+				      SPI_MEM_OP_ADDR(nor->addr_width, 0, 1),
+				      SPI_MEM_OP_DUMMY(nor->read_dummy, 1),
+				      SPI_MEM_OP_DATA_IN(0, NULL, 1)),
+		.offset = 0,
+		.length = nor->mtd.size,
+	};
+	struct spi_mem_op *op = &info.op_tmpl;
+
+	/* get transfer protocols. */
+	op->cmd.buswidth = spi_nor_get_protocol_inst_nbits(nor->read_proto);
+	op->addr.buswidth = spi_nor_get_protocol_addr_nbits(nor->read_proto);
+	op->dummy.buswidth = op->addr.buswidth;
+	op->data.buswidth = spi_nor_get_protocol_data_nbits(nor->read_proto);
+
+	/* convert the dummy cycles to the number of bytes */
+	op->dummy.nbytes = (nor->read_dummy * op->dummy.buswidth) / 8;
+
+	nor->dirmap.rdesc = devm_spi_mem_dirmap_create(nor->dev, nor->spimem,
+						       &info);
+	return PTR_ERR_OR_ZERO(nor->dirmap.rdesc);
+}
+
+static int spi_nor_create_write_dirmap(struct spi_nor *nor)
+{
+	struct spi_mem_dirmap_info info = {
+		.op_tmpl = SPI_MEM_OP(SPI_MEM_OP_CMD(nor->program_opcode, 1),
+				      SPI_MEM_OP_ADDR(nor->addr_width, 0, 1),
+				      SPI_MEM_OP_NO_DUMMY,
+				      SPI_MEM_OP_DATA_OUT(0, NULL, 1)),
+		.offset = 0,
+		.length = nor->mtd.size,
+	};
+	struct spi_mem_op *op = &info.op_tmpl;
+
+	/* get transfer protocols. */
+	op->cmd.buswidth = spi_nor_get_protocol_inst_nbits(nor->write_proto);
+	op->addr.buswidth = spi_nor_get_protocol_addr_nbits(nor->write_proto);
+	op->dummy.buswidth = op->addr.buswidth;
+	op->data.buswidth = spi_nor_get_protocol_data_nbits(nor->write_proto);
+
+	if (nor->program_opcode == SPINOR_OP_AAI_WP && nor->sst_write_second)
+		op->addr.nbytes = 0;
+
+	nor->dirmap.wdesc = devm_spi_mem_dirmap_create(nor->dev, nor->spimem,
+						       &info);
+	return PTR_ERR_OR_ZERO(nor->dirmap.wdesc);
+}
+
 static int spi_nor_probe(struct spi_mem *spimem)
 {
 	struct spi_device *spi = spimem->spi;
@@ -5326,6 +5392,14 @@ static int spi_nor_probe(struct spi_mem
 			return -ENOMEM;
 	}
 
+	ret = spi_nor_create_read_dirmap(nor);
+	if (ret)
+		return ret;
+
+	ret = spi_nor_create_write_dirmap(nor);
+	if (ret)
+		return ret;
+
 	return mtd_device_register(&nor->mtd, data ? data->parts : NULL,
 				   data ? data->nr_parts : 0);
 }
Index: linux/include/linux/mtd/spi-nor.h
===================================================================
--- linux.orig/include/linux/mtd/spi-nor.h
+++ linux/include/linux/mtd/spi-nor.h
@@ -580,6 +580,7 @@ struct flash_info;
  *                      The structure includes legacy flash parameters and
  *                      settings that can be overwritten by the spi_nor_fixups
  *                      hooks, or dynamically when parsing the SFDP tables.
+ * @dirmap:		pointers to struct spi_mem_dirmap_desc for reads/writes.
  * @priv:		the private data
  */
 struct spi_nor {
@@ -606,6 +607,11 @@ struct spi_nor {
 
 	struct spi_nor_flash_parameter params;
 
+	struct {
+		struct spi_mem_dirmap_desc *rdesc;
+		struct spi_mem_dirmap_desc *wdesc;
+	} dirmap;
+
 	void *priv;
 };
 

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