spi: differentiate between unsupported and invalid

Merge series from Miquel Raynal <[email protected]>:

I am working on spi-nand continuous read support, which lead me to check
what spi controllers were capable of.

>From a caller (and reviewer) point of view, distinguishing between error
cases has been proven useful, especially between two conditions:
- the request is totally unsupported and will never work
- the request is typically out of range somehow but a subsequent call
  with corrected parameters might work

So while I was statically reading the various drivers, I attempted to
clarify these situations and thought it might be nice to have this
upstream as well.

As ENOTSUPP is not a SUSV4 code and previous series have already been
merged to reduce its use, I also converted these few cases to EOPNOTSUP
instead, but if anybody doesn't like these changes, it can be dropped.

4 files changed, 16 insertions, 14 deletions

diff --git a/drivers/spi/spi-dw-bt1.c b/drivers/spi/spi-dw-bt1.c
index 5391bcac305c..4577e8096cd9 100644
--- a/drivers/spi/spi-dw-bt1.c
+++ b/drivers/spi/spi-dw-bt1.c
@@ -55,13 +55,15 @@ static int dw_spi_bt1_dirmap_create(struct spi_mem_dirmap_desc *desc)
 	    !dwsbt1->dws.mem_ops.supports_op(desc->mem, &desc->info.op_tmpl))
 		return -EOPNOTSUPP;
 
+	if (desc->info.op_tmpl.data.dir != SPI_MEM_DATA_IN)
+		return -EOPNOTSUPP;
+
 	/*
 	 * Make sure the requested region doesn't go out of the physically
-	 * mapped flash memory bounds and the operation is read-only.
+	 * mapped flash memory bounds.
 	 */
-	if (desc->info.offset + desc->info.length > dwsbt1->map_len ||
-	    desc->info.op_tmpl.data.dir != SPI_MEM_DATA_IN)
-		return -EOPNOTSUPP;
+	if (desc->info.offset + desc->info.length > dwsbt1->map_len)
+		return -EINVAL;
 
 	return 0;
 }
diff --git a/drivers/spi/spi-mxic.c b/drivers/spi/spi-mxic.c
index 60c9f3048ac9..6156d691630a 100644
--- a/drivers/spi/spi-mxic.c
+++ b/drivers/spi/spi-mxic.c
@@ -496,7 +496,7 @@ static int mxic_spi_mem_dirmap_create(struct spi_mem_dirmap_desc *desc)
 	struct mxic_spi *mxic = spi_controller_get_devdata(desc->mem->spi->controller);
 
 	if (!mxic->linear.map)
-		return -EINVAL;
+		return -EOPNOTSUPP;
 
 	if (desc->info.offset + desc->info.length > U32_MAX)
 		return -EINVAL;
diff --git a/drivers/spi/spi-rpc-if.c b/drivers/spi/spi-rpc-if.c
index e11146932828..d3f07fd719bd 100644
--- a/drivers/spi/spi-rpc-if.c
+++ b/drivers/spi/spi-rpc-if.c
@@ -95,16 +95,16 @@ static int rpcif_spi_mem_dirmap_create(struct spi_mem_dirmap_desc *desc)
 		spi_controller_get_devdata(desc->mem->spi->controller);
 
 	if (desc->info.offset + desc->info.length > U32_MAX)
-		return -ENOTSUPP;
+		return -EINVAL;
 
 	if (!rpcif_spi_mem_supports_op(desc->mem, &desc->info.op_tmpl))
-		return -ENOTSUPP;
+		return -EOPNOTSUPP;
 
-	if (!rpc->dirmap && desc->info.op_tmpl.data.dir == SPI_MEM_DATA_IN)
-		return -ENOTSUPP;
+	if (!rpc->dirmap)
+		return -EOPNOTSUPP;
 
-	if (desc->info.op_tmpl.data.dir == SPI_MEM_DATA_OUT)
-		return -ENOTSUPP;
+	if (desc->info.op_tmpl.data.dir != SPI_MEM_DATA_IN)
+		return -EOPNOTSUPP;
 
 	return 0;
 }
diff --git a/drivers/spi/spi-wpcm-fiu.c b/drivers/spi/spi-wpcm-fiu.c
index 6b16a22cc3a4..886d6d7771d4 100644
--- a/drivers/spi/spi-wpcm-fiu.c
+++ b/drivers/spi/spi-wpcm-fiu.c
@@ -378,7 +378,7 @@ static int wpcm_fiu_dirmap_create(struct spi_mem_dirmap_desc *desc)
 	int cs = spi_get_chipselect(desc->mem->spi, 0);
 
 	if (desc->info.op_tmpl.data.dir != SPI_MEM_DATA_IN)
-		return -ENOTSUPP;
+		return -EOPNOTSUPP;
 
 	/*
 	 * Unfortunately, FIU only supports a 16 MiB direct mapping window (per
@@ -387,11 +387,11 @@ static int wpcm_fiu_dirmap_create(struct spi_mem_dirmap_desc *desc)
 	 * flashes that are bigger than 16 MiB.
 	 */
 	if (desc->info.offset + desc->info.length > MAX_MEMORY_SIZE_PER_CS)
-		return -ENOTSUPP;
+		return -EINVAL;
 
 	/* Don't read past the memory window */
 	if (cs * MAX_MEMORY_SIZE_PER_CS + desc->info.offset + desc->info.length > fiu->memory_size)
-		return -ENOTSUPP;
+		return -EINVAL;
 
 	return 0;
 }