[PATCH v10 18/19] mtd: spi-nor: run controller optimization before dirmap creation

[Santhosh Kumar K]

Run controller optimization in spi_nor_probe() before creating dirmaps
so the validated frequency is available at dirmap construction time.

Store the configured read op template in nor->max_read_op and pass it
to spi_mem_execute_tuning(). On success the controller sets
max_read_op.max_freq to the calibrated rate.

spi_nor_spimem_get_read_op() propagates nor->max_read_op.max_freq into
an op only when that op's protocol shape (cmd/addr/data buswidth,
addr.nbytes, DTR-ness) still matches what was actually tuned. Callers
such as spi_nor_otp_read_secr() temporarily swap in a different
read_opcode/read_proto/read_dummy to read a security register; without
this check, the calibrated frequency would be applied to that unrelated,
uncalibrated protocol and could corrupt the read. Ops matching the tuned
shape -- the dirmap template and regular reads -- still get the
validated frequency automatically.

Optimization failure is non-fatal; the device operates at the
conservative base rate.

Signed-off-by: Santhosh Kumar K <s-k6 at ti.com>
---
 drivers/mtd/spi-nor/core.c  | 28 ++++++++++++++++++++++++++++
 include/linux/mtd/spi-nor.h |  4 ++++
 2 files changed, 32 insertions(+)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index d114d828a788..4597f07a207f 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -217,6 +217,23 @@ static struct spi_mem_op spi_nor_spimem_get_read_op(struct spi_nor *nor)
 	if (spi_nor_protocol_is_dtr(nor->read_proto))
 		op.dummy.nbytes *= 2;
 
+	/*
+	 * Propagate the validated frequency only if this op still has the
+	 * same protocol shape as the one that was actually tuned. Callers
+	 * such as spi_nor_otp_read_secr() temporarily swap in a different
+	 * read_opcode/read_proto/read_dummy; applying the high-speed
+	 * calibrated frequency to that unrelated protocol would run it too
+	 * fast for its own (uncalibrated) timing.
+	 */
+	if (op.cmd.buswidth == nor->max_read_op.cmd.buswidth &&
+	    op.cmd.dtr == nor->max_read_op.cmd.dtr &&
+	    op.addr.nbytes == nor->max_read_op.addr.nbytes &&
+	    op.addr.buswidth == nor->max_read_op.addr.buswidth &&
+	    op.addr.dtr == nor->max_read_op.addr.dtr &&
+	    op.data.buswidth == nor->max_read_op.data.buswidth &&
+	    op.data.dtr == nor->max_read_op.data.dtr)
+		op.max_freq = nor->max_read_op.max_freq;
+
 	return op;
 }
 
@@ -3622,6 +3639,17 @@ static int spi_nor_probe(struct spi_mem *spimem)
 			return -ENOMEM;
 	}
 
+	/*
+	 * Populate the persistent template and run PHY tuning before dirmap
+	 * creation so the validated frequency feeds into the dirmap op.
+	 * Tuning failure is non-fatal; the device operates at base speed.
+	 */
+	nor->max_read_op = spi_nor_spimem_get_read_op(nor);
+
+	ret = spi_mem_execute_tuning(spimem, &nor->max_read_op, NULL);
+	if (ret && ret != -EOPNOTSUPP)
+		dev_dbg(dev, "Controller optimization failed: %d\n", ret);
+
 	ret = spi_nor_create_read_dirmap(nor);
 	if (ret)
 		return ret;
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index b3e3c6b10186..1f8aff53a2a8 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -374,6 +374,8 @@ struct spi_nor_flash_parameter;
  *                      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.
+ * @max_read_op:	persistent read op template updated by execute_tuning
+ *			with the validated operating speed.
  * @priv:		pointer to the private data
  */
 struct spi_nor {
@@ -416,6 +418,8 @@ struct spi_nor {
 		struct spi_mem_dirmap_desc *wdesc;
 	} dirmap;
 
+	struct spi_mem_op max_read_op;
+
 	void *priv;
 };
 
-- 
2.34.1