drivers: flash: flash_mspi_nor: support custom read frequency

Many flash chips support a higher read frequency than other operations.
Support specifying a custom read frequency to take advantage of the
performance improvements available with this approach.

Signed-off-by: Daniel DeGrasse <[email protected]>

Author: danieldegrasse

drivers/flash/flash_mspi_nor.c

@@ -354,6 +354,20 @@ static int api_read(const struct device *dev, off_t addr, void *dest,
 		return rc;
 	}
 
+	if (dev_config->read_freq != 0) {
+		/* Set custom read frequency */
+		struct mspi_dev_cfg read_freq_cfg = {
+			.freq = dev_config->read_freq,
+		};
+
+		rc = mspi_dev_config(dev_config->bus, &dev_config->mspi_id,
+				     MSPI_DEVICE_CONFIG_FREQUENCY, &read_freq_cfg);
+		if (rc < 0) {
+			LOG_ERR("Could not set read frequency: %d", rc);
+			goto release_and_exit;
+		}
+	}
+
 	while (size > 0) {
 		uint32_t to_read;
 
@@ -375,6 +389,17 @@ static int api_read(const struct device *dev, off_t addr, void *dest,
 		size -= to_read;
 	}
 
+release_and_exit:
+	if (rc == 0 && dev_config->read_freq != 0) {
+		/* Restore normal frequency */
+		rc = mspi_dev_config(dev_config->bus, &dev_config->mspi_id,
+				     MSPI_DEVICE_CONFIG_FREQUENCY,
+				     &dev_config->mspi_nor_cfg);
+		if (rc < 0) {
+			LOG_ERR("Could not restore normal frequency: %d", rc);
+		}
+	}
+
 	release(dev);
 
 	if (rc < 0) {
@@ -1342,6 +1367,7 @@ BUILD_ASSERT((FLASH_SIZE(inst) % CONFIG_FLASH_MSPI_NOR_LAYOUT_PAGE_SIZE) == 0, \
 		.reset_recovery_us = DT_INST_PROP_OR(inst, t_reset_recovery, 0)	\
 				   / 1000,					\
 		.transfer_timeout = DT_INST_PROP(inst, transfer_timeout),	\
+		.read_freq = DT_INST_PROP_OR(inst, read_frequency, 0),	        \
 		FLASH_PAGE_LAYOUT_DEFINE(inst)					\
 		.jedec_id = DT_INST_PROP_OR(inst, jedec_id, {0}),		\
 		.quirks = FLASH_QUIRKS(inst),					\

drivers/flash/flash_mspi_nor.h

@@ -88,6 +88,7 @@ struct flash_mspi_nor_config {
 #endif
 	uint32_t reset_recovery_us;
 	uint32_t transfer_timeout;
+	uint32_t read_freq;
 #if defined(CONFIG_FLASH_PAGE_LAYOUT)
 	struct flash_pages_layout layout;
 #endif

dts/bindings/mtd/jedec,mspi-nor.yaml

@@ -60,3 +60,9 @@ properties:
     description: |
       When set, the flash driver performs software reset of the flash chip
       at initialization.
+
+  read-frequency:
+    type: int
+    description: |
+      Frequency, in Hz, to be used for read operations. If not specified,
+      the driver uses the same frequency as for other operations.