alif/ospi_flash: Add 16-bit words swap flash setting.

The byte order (endianness) seems to be swapped when read in 8D-8D-8D in
XIP mode, for most flashes, with the exception of MX which seems to swap
half-words.

This commit adds a flash setting to allow parts to enable half-word swap
when data is written, to fix this issue.  By default, only endianness is
fixed.

Tested with both MX and ISSI parts on AE3, flash test and simple file
write/read.

Signed-off-by: iabdalkader <[email protected]>

Author: iabdalkader

ports/alif/ospi_flash.c

@@ -414,8 +414,16 @@ static int ospi_flash_write_page(uint32_t addr, uint32_t len, const uint8_t *src
     ospi_push(&self->cfg, addr);
 
     const uint32_t *src32 = (const uint32_t *)src;
-    for (; len; len -= 4) {
-        ospi_push(&self->cfg, __ROR(*src32++, 16));
+    if (self->set->bswap16) {
+        // MX flashes swap 16-bit words when read in 8D-8D-8D.
+        for (; len; len -= 4) {
+            ospi_push(&self->cfg, __ROR(*src32++, 16));
+        }
+    } else {
+        // For the rest of the flashes, we just correct the endianness.
+        for (; len; len -= 4) {
+            ospi_push(&self->cfg, __REV(*src32++));
+        }
     }
 
     ospi_writel((&self->cfg), ser, self->cfg.ser);

ports/alif/ospi_flash.h

@@ -61,6 +61,7 @@ typedef struct _ospi_flash_settings_t {
     int (*flash_init)(struct _ospi_flash_t *);
     uint8_t octal_mode;
     bool rxds;
+    bool bswap16;
     uint8_t inst_len;
     uint8_t xip_data_len;
     uint16_t read_sr;

ports/alif/ospi_flash_settings.h

@@ -34,6 +34,7 @@
     .flash_init = ospi_flash_mx_init, \
     .octal_mode = OSPI_FLASH_OCTAL_MODE_DDD, \
     .rxds = true, \
+    .bswap16 = true, \
     .inst_len = OSPI_INST_L_16bit, \
     .xip_data_len = OSPI_DATA_L_16bit, \
     .read_sr = 0x05fa, \
@@ -50,6 +51,7 @@
     .flash_init = ospi_flash_issi_init, \
     .octal_mode = OSPI_FLASH_OCTAL_MODE_DDD, \
     .rxds = false, \
+    .bswap16 = false, \
     .inst_len = OSPI_INST_L_8bit, \
     .xip_data_len = OSPI_DATA_L_16bit, \
     .read_sr = 0x05, \
@@ -65,7 +67,8 @@
 #define OSPI_FLASH_SETTINGS_IS25 \
     .flash_init = ospi_flash_issi_init, \
     .octal_mode = OSPI_FLASH_OCTAL_MODE_DDD, \
-    .rxds = true, \
+    .rxds = false, \
+    .bswap16 = false, \
     .inst_len = OSPI_INST_L_8bit, \
     .xip_data_len = OSPI_DATA_L_16bit, \
     .read_sr = 0x05, \