[PATCH v5 04/13] spi: spi-mem: Create a helper to gather all the supports_op checks

[Miquel Raynal <miquel.raynal@bootlin.com>]

So far we check the support for:
- regular operations
- dtr operations
Soon, we will also need to check the support for ECC operations.

As the combinatorial will increase exponentially, let's gather all the
checks in a single generic function which takes a capabilities structure
as input. This new helper is supposed to be called by the currently
exported functions instead of repeating a similar implementation.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/spi/spi-mem.c       | 34 +++++++++++++++++++++++++---------
 include/linux/spi/spi-mem.h |  8 ++++++++
 2 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
index 37f4443ce9a0..4c6944d7b174 100644
--- a/drivers/spi/spi-mem.c
+++ b/drivers/spi/spi-mem.c
@@ -160,26 +160,42 @@ static bool spi_mem_check_buswidth(struct spi_mem *mem,
 	return true;
 }
 
+static bool spi_mem_generic_supports_op(struct spi_mem *mem,
+					const struct spi_mem_op *op,
+					struct spi_mem_controller_caps *caps)
+{
+	if (!caps->dtr) {
+		if (op->cmd.dtr || op->addr.dtr ||
+		    op->dummy.dtr || op->data.dtr)
+			return false;
+
+		if (op->cmd.nbytes != 1)
+			return false;
+	} else {
+		if (op->cmd.nbytes != 2)
+			return false;
+	}
+
+	return spi_mem_check_buswidth(mem, op);
+}
+
 bool spi_mem_dtr_supports_op(struct spi_mem *mem,
 			     const struct spi_mem_op *op)
 {
-	if (op->cmd.nbytes != 2)
-		return false;
+	struct spi_mem_controller_caps caps = {
+		.dtr = true,
+	};
 
-	return spi_mem_check_buswidth(mem, op);
+	return spi_mem_generic_supports_op(mem, op, &caps);
 }
 EXPORT_SYMBOL_GPL(spi_mem_dtr_supports_op);
 
 bool spi_mem_default_supports_op(struct spi_mem *mem,
 				 const struct spi_mem_op *op)
 {
-	if (op->cmd.dtr || op->addr.dtr || op->dummy.dtr || op->data.dtr)
-		return false;
+	struct spi_mem_controller_caps caps = {};
 
-	if (op->cmd.nbytes != 1)
-		return false;
-
-	return spi_mem_check_buswidth(mem, op);
+	return spi_mem_generic_supports_op(mem, op, &caps);
 }
 EXPORT_SYMBOL_GPL(spi_mem_default_supports_op);
 
diff --git a/include/linux/spi/spi-mem.h b/include/linux/spi/spi-mem.h
index 85e2ff7b840d..f365efcfb719 100644
--- a/include/linux/spi/spi-mem.h
+++ b/include/linux/spi/spi-mem.h
@@ -220,6 +220,14 @@ static inline void *spi_mem_get_drvdata(struct spi_mem *mem)
 	return mem->drvpriv;
 }
 
+/**
+ * struct spi_mem_controller_caps - SPI memory controller capabilities
+ * @dtr: Supports DTR operations
+ */
+struct spi_mem_controller_caps {
+	bool dtr;
+};
+
 /**
  * struct spi_controller_mem_ops - SPI memory operations
  * @adjust_op_size: shrink the data xfer of an operation to match controller's
-- 
2.27.0