[RFC PATCH 6/8] mtd: spi-nor: Prepare the introduction of a new locking mechanism

[Miquel Raynal]

This commit alone just introduces two new "lock and prepare" pairs of
helpers which do the exact same thing as before. They will soon be
improved in a followup commit which actually brings the logic, but I
figured out it was more readable to do it this way.

One new pair is suffixed _pe which stands for "program and erase" and
hence is being called by spi_nor_write() and spi_nor_erase().

The other pair is suffixed _rd which stands for "read" and hence is
being called by spi_nor_read().

One note however, these extra helpers will need to know the operation
range, so they come with two new parameters to define it. Otherwise
there is no functional change.

Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>
---
 drivers/mtd/spi-nor/core.c | 57 ++++++++++++++++++++++++++++++++++----
 1 file changed, 51 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 048665252a80..3d8e5f9961b9 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -1081,6 +1081,7 @@ static void spi_nor_unprep(struct spi_nor *nor)
 		nor->controller_ops->unprepare(nor);
 }
 
+/* Generic helpers for internal locking and serialization */
 int spi_nor_lock_and_prep(struct spi_nor *nor)
 {
 	int ret;
@@ -1101,6 +1102,48 @@ void spi_nor_unlock_and_unprep(struct spi_nor *nor)
 	spi_nor_unprep(nor);
 }
 
+/* Internal locking helpers for program and erase operations */
+static int spi_nor_lock_and_prep_pe(struct spi_nor *nor, loff_t start, size_t len)
+{
+	int ret;
+
+	ret = spi_nor_prep(nor);
+	if (ret)
+		return ret;
+
+	mutex_lock(&nor->lock);
+
+	return 0;
+}
+
+static void spi_nor_unlock_and_unprep_pe(struct spi_nor *nor, loff_t start, size_t len)
+{
+	mutex_unlock(&nor->lock);
+
+	spi_nor_unprep(nor);
+}
+
+/* Internal locking helpers for read operations */
+static int spi_nor_lock_and_prep_rd(struct spi_nor *nor, loff_t start, size_t len)
+{
+	int ret;
+
+	ret = spi_nor_prep(nor);
+	if (ret)
+		return ret;
+
+	mutex_lock(&nor->lock);
+
+	return 0;
+}
+
+static void spi_nor_unlock_and_unprep_rd(struct spi_nor *nor, loff_t start, size_t len)
+{
+	mutex_unlock(&nor->lock);
+
+	spi_nor_unprep(nor);
+}
+
 static u32 spi_nor_convert_addr(struct spi_nor *nor, loff_t addr)
 {
 	if (!nor->params->convert_addr)
@@ -1454,7 +1497,7 @@ static int spi_nor_erase(struct mtd_info *mtd, struct erase_info *instr)
 	addr = instr->addr;
 	len = instr->len;
 
-	ret = spi_nor_lock_and_prep(nor);
+	ret = spi_nor_lock_and_prep_pe(nor, addr, len);
 	if (ret)
 		return ret;
 
@@ -1517,7 +1560,7 @@ static int spi_nor_erase(struct mtd_info *mtd, struct erase_info *instr)
 	ret = spi_nor_write_disable(nor);
 
 erase_err:
-	spi_nor_unlock_and_unprep(nor);
+	spi_nor_unlock_and_unprep_pe(nor, addr, len);
 
 	return ret;
 }
@@ -1704,7 +1747,7 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
 
 	dev_dbg(nor->dev, "from 0x%08x, len %zd\n", (u32)from, len);
 
-	ret = spi_nor_lock_and_prep(nor);
+	ret = spi_nor_lock_and_prep_rd(nor, from, len);
 	if (ret)
 		return ret;
 
@@ -1731,7 +1774,8 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
 	ret = 0;
 
 read_err:
-	spi_nor_unlock_and_unprep(nor);
+	spi_nor_unlock_and_unprep_rd(nor, from, len);
+
 	return ret;
 }
 
@@ -1750,7 +1794,7 @@ static int spi_nor_write(struct mtd_info *mtd, loff_t to, size_t len,
 
 	dev_dbg(nor->dev, "to 0x%08x, len %zd\n", (u32)to, len);
 
-	ret = spi_nor_lock_and_prep(nor);
+	ret = spi_nor_lock_and_prep_pe(nor, to, len);
 	if (ret)
 		return ret;
 
@@ -1792,7 +1836,8 @@ static int spi_nor_write(struct mtd_info *mtd, loff_t to, size_t len,
 	}
 
 write_err:
-	spi_nor_unlock_and_unprep(nor);
+	spi_nor_unlock_and_unprep_pe(nor, to, len);
+
 	return ret;
 }
 
-- 
2.34.1