[PATCH v2] spi: cadence_qspi: Select flash subnode at runtime

[Udit Kumar]

Currently spi driver gets flash parameter from first subnode.

Few boards have more than one flash with different parameters
and selection of flash is done by on board switch settings.
In such case, uboot needs to be recompiled with updated
device tree to align with board switch settings.

This patch allows to select flash node at runtime.

Boards those are supporting multiple flashes
needs to implement cadence_qspi_get_subnode function and return correct
flash node.

Cc: Apurva Nandan <a-nandan at ti.com>
Signed-off-by: Udit Kumar <u-kumar1 at ti.com>
Reviewed-by: Neha Malcom Francis <n-francis at ti.com>
---
One of such platform is J721S2 EVM
link https://www.ti.com/lit/pdf/spruj69
Fig 3.1, Page 18 has details of two flashes connected with one controller

Change log:
Changes in v2
- Corrected link in comment
- removed extra space
- Added Reviewed-by, after addressing v1 feedback
- link to v1
https://lore.kernel.org/all/20230907092143.4110817-1-u-kumar1@ti.com/

 drivers/spi/cadence_qspi.c | 7 ++++++-
 drivers/spi/cadence_qspi.h | 1 +
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/cadence_qspi.c b/drivers/spi/cadence_qspi.c
index cc3a54f295..eb7fbf83d0 100644
--- a/drivers/spi/cadence_qspi.c
+++ b/drivers/spi/cadence_qspi.c
@@ -40,6 +40,11 @@ __weak int cadence_qspi_versal_flash_reset(struct udevice *dev)
 	return 0;
 }
 
+__weak ofnode cadence_qspi_get_subnode(struct udevice *dev)
+{
+	return dev_read_first_subnode(dev);
+}
+
 static int cadence_spi_write_speed(struct udevice *bus, uint hz)
 {
 	struct cadence_spi_priv *priv = dev_get_priv(bus);
@@ -401,7 +406,7 @@ static int cadence_spi_of_to_plat(struct udevice *bus)
 	plat->is_dma = dev_read_bool(bus, "cdns,is-dma");
 
 	/* All other parameters are embedded in the child node */
-	subnode = dev_read_first_subnode(bus);
+	subnode = cadence_qspi_get_subnode(bus);
 	if (!ofnode_valid(subnode)) {
 		printf("Error: subnode with SPI flash config missing!\n");
 		return -ENODEV;
diff --git a/drivers/spi/cadence_qspi.h b/drivers/spi/cadence_qspi.h
index 1c59d1a9d9..12825f8911 100644
--- a/drivers/spi/cadence_qspi.h
+++ b/drivers/spi/cadence_qspi.h
@@ -304,6 +304,7 @@ int cadence_qspi_apb_dma_read(struct cadence_spi_priv *priv,
 int cadence_qspi_apb_wait_for_dma_cmplt(struct cadence_spi_priv *priv);
 int cadence_qspi_apb_exec_flash_cmd(void *reg_base, unsigned int reg);
 int cadence_qspi_versal_flash_reset(struct udevice *dev);
+ofnode cadence_qspi_get_subnode(struct udevice *dev);
 void cadence_qspi_apb_enable_linear_mode(bool enable);
 
 #endif /* __CADENCE_QSPI_H__ */
-- 
2.34.1