drivers/sdcard: Fix address calculation on v2 SDSC cards.

For v2 cards that are standard capacity the read/write/erase commands take
byte address values.  Use the result of CMD58 to distinguish SDSC from
SDHC/SDXC.
Signed-off-by: Damien George <damien@micropython.org>

drivers/sdcard/sdcard.py

@@ -120,6 +120,7 @@ class SDCard:
         for i in range(_CMD_TIMEOUT):
             self.cmd(55, 0, 0)
             if self.cmd(41, 0, 0) == 0:
+                # SDSC card, uses byte addressing in read/write/erase commands
                 self.cdv = 512
                 # print("[SDCard] v1 card")
                 return
@@ -131,8 +132,14 @@ class SDCard:
             self.cmd(58, 0, 0, 4)
             self.cmd(55, 0, 0)
             if self.cmd(41, 0x40000000, 0) == 0:
-                self.cmd(58, 0, 0, 4)
-                self.cdv = 1
+                self.cmd(58, 0, 0, -4)  # 4-byte response, negative means keep the first byte
+                ocr = self.tokenbuf[0]  # get first byte of response, which is OCR
+                if not ocr & 0x40:
+                    # SDSC card, uses byte addressing in read/write/erase commands
+                    self.cdv = 512
+                else:
+                    # SDHC/SDXC card, uses block addressing in read/write/erase commands
+                    self.cdv = 1
                 # print("[SDCard] v2 card")
                 return
         raise OSError("timeout waiting for v2 card")
@@ -159,6 +166,10 @@ class SDCard:
             response = self.tokenbuf[0]
             if not (response & 0x80):
                 # this could be a big-endian integer that we are getting here
+                # if final<0 then store the first byte to tokenbuf and discard the rest
+                if final < 0:
+                    self.spi.readinto(self.tokenbuf, 0xFF)
+                    final = -1 - final
                 for j in range(final):
                     self.spi.write(b"\xff")
                 if release: