QSPIFBlockDevice: Handle CR3NV[1] quirk on S25FS512S

Cypress S25FS512S's SFDP table suggests checking bit-1 of the register
25FS512S as part of configuration detection. This bit should equal 1
in order for configuration to be correctly determined, but it is 0 on
actual hardware. We add a quirk to work around this.

Note: In Mbed OS, vendor-specific quirks are handled in block devices,
and the SFDP class is agnostic of any quirks. So when the SFDP class
requests the value of CR3NV, we let QSPIFBlockDevice's SFDP reader
callback to set bit-1 of the output to 1 to allow the SFDP class to
work correctly.

storage/blockdevice/COMPONENT_QSPIF/include/QSPIF/QSPIFBlockDevice.h

@@ -375,6 +375,7 @@ class QSPIFBlockDevice : public mbed::BlockDevice {
     int _quad_enable_bit;
 
     bool _needs_fast_mode;
+    bool _CR3NV_quirk;
 
     // Clear block protection
     qspif_clear_protection_method_t _clear_protection_method;

storage/blockdevice/COMPONENT_QSPIF/source/QSPIFBlockDevice.cpp

@@ -176,6 +176,9 @@ QSPIFBlockDevice::QSPIFBlockDevice(PinName io0, PinName io1, PinName io2, PinNam
     // Set default 4-byte addressing extension register write instruction
     _attempt_4_byte_addressing = true;
     _4byte_msb_reg_write_inst = QSPIF_INST_4BYTE_REG_WRITE_DEFAULT;
+
+    // Quirk for CR3NV[1] on Cypress S25FS512S
+    _CR3NV_quirk = false;
 }
 
 int QSPIFBlockDevice::init()
@@ -1099,6 +1102,15 @@ int QSPIFBlockDevice::_handle_vendor_quirks()
             tr_debug("Applying quirks for ISSI");
             _num_status_registers = 1;
             break;
+        case 0x01:
+            if (vendor_device_ids[1] == 0x02 && vendor_device_ids[2] == 0x20) {
+                // On a Cypress S25FS512S flash chip, bit-1 of the register CR3NV is
+                // expected to be 1 but its actual value is 0 on manufactured hardware.
+                // In order for configuration detection to work, this chip needs to be
+                // specially handled.
+                _CR3NV_quirk = true;
+            }
+            break;
     }
 
     return 0;
@@ -1469,6 +1481,14 @@ int QSPIFBlockDevice::_qspi_send_read_sfdp_command(mbed::bd_addr_t addr, mbed::s
         return status;
     }
 
+    // Handle CR3NV[1] quirk.
+    const mbed::bd_addr_t register_CR3NV = 0x000004;
+    if (_CR3NV_quirk && (addr == register_CR3NV)) {
+        // If we reach here, rx_buffer is guaranteed to be non-null
+        // because it's been checked by _qspi.read() above.
+        static_cast<uint8_t *>(rx_buffer)[0] |= 0x01;
+    }
+
     return QSPI_STATUS_OK;
 }