[PATCH v2 1/3] mtd: rawnand: Check the data only read pattern only once

[Miquel Raynal]

Instead of checking if a pattern is supported each time we need it,
let's create a bitfield that only the core would be allowed to fill at
startup time. The core and the individual drivers may then use it in
order to check what operation they should use. This bitfield is supposed
to grow over time.

Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>
---
 drivers/mtd/nand/raw/nand_base.c  | 20 ++++++++++++++++++++
 drivers/mtd/nand/raw/nand_jedec.c |  3 +--
 drivers/mtd/nand/raw/nand_onfi.c  |  3 +--
 include/linux/mtd/rawnand.h       |  8 ++++++++
 4 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index 33f2c98a030e..83bfb1ba2fa3 100644
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -4991,6 +4991,24 @@ nand_manufacturer_name(const struct nand_manufacturer_desc *manufacturer_desc)
 	return manufacturer_desc ? manufacturer_desc->name : "Unknown";
 }
 
+static void rawnand_check_data_only_read_support(struct nand_chip *chip)
+{
+	/* Use an arbitrary size for the check */
+	if (!nand_read_data_op(chip, NULL, SZ_512, true, true))
+		chip->controller->supported_op.data_only_read = 1;
+}
+
+static void rawnand_early_check_supported_ops(struct nand_chip *chip)
+{
+	/* The supported_op fields should not be set by individual drivers */
+	WARN_ON_ONCE(chip->controller->supported_op.data_only_read);
+
+	if (!nand_has_exec_op(chip))
+		return;
+
+	rawnand_check_data_only_read_support(chip);
+}
+
 /*
  * Get the flash and manufacturer id and lookup if the type is supported.
  */
@@ -5023,6 +5041,8 @@ static int nand_detect(struct nand_chip *chip, struct nand_flash_dev *type)
 	/* Select the device */
 	nand_select_target(chip, 0);
 
+	rawnand_early_check_supported_ops(chip);
+
 	/* Send the command for reading device ID */
 	ret = nand_readid_op(chip, 0, id_data, 2);
 	if (ret)
diff --git a/drivers/mtd/nand/raw/nand_jedec.c b/drivers/mtd/nand/raw/nand_jedec.c
index 85b6d9372d80..836757717660 100644
--- a/drivers/mtd/nand/raw/nand_jedec.c
+++ b/drivers/mtd/nand/raw/nand_jedec.c
@@ -46,8 +46,7 @@ int nand_jedec_detect(struct nand_chip *chip)
 	if (!p)
 		return -ENOMEM;
 
-	if (!nand_has_exec_op(chip) ||
-	    !nand_read_data_op(chip, p, sizeof(*p), true, true))
+	if (!nand_has_exec_op(chip) || chip->controller->supported_op.data_only_read)
 		use_datain = true;
 
 	for (i = 0; i < JEDEC_PARAM_PAGES; i++) {
diff --git a/drivers/mtd/nand/raw/nand_onfi.c b/drivers/mtd/nand/raw/nand_onfi.c
index 7586befce7f9..f15ef90aec8c 100644
--- a/drivers/mtd/nand/raw/nand_onfi.c
+++ b/drivers/mtd/nand/raw/nand_onfi.c
@@ -166,8 +166,7 @@ int nand_onfi_detect(struct nand_chip *chip)
 	if (!pbuf)
 		return -ENOMEM;
 
-	if (!nand_has_exec_op(chip) ||
-	    !nand_read_data_op(chip, &pbuf[0], sizeof(*pbuf), true, true))
+	if (!nand_has_exec_op(chip) || chip->controller->supported_op.data_only_read)
 		use_datain = true;
 
 	for (i = 0; i < ONFI_PARAM_PAGES; i++) {
diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
index dcf90144d70b..28c5dce782dd 100644
--- a/include/linux/mtd/rawnand.h
+++ b/include/linux/mtd/rawnand.h
@@ -1094,10 +1094,18 @@ struct nand_controller_ops {
  *
  * @lock:		lock used to serialize accesses to the NAND controller
  * @ops:		NAND controller operations.
+ * @supported_op:	NAND controller known-to-be-supported operations,
+ *			only writable by the core after initial checking.
+ * @supported_op.data_only_read: The controller supports reading more data from
+ *			the bus without restarting an entire read operation nor
+ *			changing the column.
  */
 struct nand_controller {
 	struct mutex lock;
 	const struct nand_controller_ops *ops;
+	struct {
+		unsigned int data_only_read: 1;
+	} supported_op;
 };
 
 static inline void nand_controller_init(struct nand_controller *nfc)
-- 
2.34.1