From 995e1f732e43a5b85e5961e9791977b0cada7c50 Mon Sep 17 00:00:00 2001
From: gdisirio <gdisirio@35acf78f-673a-0410-8e92-d51de3d6d3f4>
Date: Sun, 12 Feb 2012 10:05:10 +0000
Subject: Reintroduced CRC7 calculation.

git-svn-id: svn://svn.code.sf.net/p/chibios/svn/trunk@3954 35acf78f-673a-0410-8e92-d51de3d6d3f4
---
 os/hal/src/mmc_spi.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 49 insertions(+), 6 deletions(-)

(limited to 'os/hal')

diff --git a/os/hal/src/mmc_spi.c b/os/hal/src/mmc_spi.c
index 079dcf3c0..c7b3372f2 100644
--- a/os/hal/src/mmc_spi.c
+++ b/os/hal/src/mmc_spi.c
@@ -48,10 +48,53 @@
 /* Driver local variables.                                                   */
 /*===========================================================================*/
 
+/**
+ * @brief   Lookup table for CRC-7 ( based on polynomial x^7 + x^3 + 1).
+ */
+static const uint8_t crc7_lookup_table[256] = {
+  0x00, 0x09, 0x12, 0x1b, 0x24, 0x2d, 0x36, 0x3f, 0x48, 0x41, 0x5a, 0x53,
+  0x6c, 0x65, 0x7e, 0x77, 0x19, 0x10, 0x0b, 0x02, 0x3d, 0x34, 0x2f, 0x26,
+  0x51, 0x58, 0x43, 0x4a, 0x75, 0x7c, 0x67, 0x6e, 0x32, 0x3b, 0x20, 0x29,
+  0x16, 0x1f, 0x04, 0x0d, 0x7a, 0x73, 0x68, 0x61, 0x5e, 0x57, 0x4c, 0x45,
+  0x2b, 0x22, 0x39, 0x30, 0x0f, 0x06, 0x1d, 0x14, 0x63, 0x6a, 0x71, 0x78,
+  0x47, 0x4e, 0x55, 0x5c, 0x64, 0x6d, 0x76, 0x7f, 0x40, 0x49, 0x52, 0x5b,
+  0x2c, 0x25, 0x3e, 0x37, 0x08, 0x01, 0x1a, 0x13, 0x7d, 0x74, 0x6f, 0x66,
+  0x59, 0x50, 0x4b, 0x42, 0x35, 0x3c, 0x27, 0x2e, 0x11, 0x18, 0x03, 0x0a,
+  0x56, 0x5f, 0x44, 0x4d, 0x72, 0x7b, 0x60, 0x69, 0x1e, 0x17, 0x0c, 0x05,
+  0x3a, 0x33, 0x28, 0x21, 0x4f, 0x46, 0x5d, 0x54, 0x6b, 0x62, 0x79, 0x70,
+  0x07, 0x0e, 0x15, 0x1c, 0x23, 0x2a, 0x31, 0x38, 0x41, 0x48, 0x53, 0x5a,
+  0x65, 0x6c, 0x77, 0x7e, 0x09, 0x00, 0x1b, 0x12, 0x2d, 0x24, 0x3f, 0x36,
+  0x58, 0x51, 0x4a, 0x43, 0x7c, 0x75, 0x6e, 0x67, 0x10, 0x19, 0x02, 0x0b,
+  0x34, 0x3d, 0x26, 0x2f, 0x73, 0x7a, 0x61, 0x68, 0x57, 0x5e, 0x45, 0x4c,
+  0x3b, 0x32, 0x29, 0x20, 0x1f, 0x16, 0x0d, 0x04, 0x6a, 0x63, 0x78, 0x71,
+  0x4e, 0x47, 0x5c, 0x55, 0x22, 0x2b, 0x30, 0x39, 0x06, 0x0f, 0x14, 0x1d,
+  0x25, 0x2c, 0x37, 0x3e, 0x01, 0x08, 0x13, 0x1a, 0x6d, 0x64, 0x7f, 0x76,
+  0x49, 0x40, 0x5b, 0x52, 0x3c, 0x35, 0x2e, 0x27, 0x18, 0x11, 0x0a, 0x03,
+  0x74, 0x7d, 0x66, 0x6f, 0x50, 0x59, 0x42, 0x4b, 0x17, 0x1e, 0x05, 0x0c,
+  0x33, 0x3a, 0x21, 0x28, 0x5f, 0x56, 0x4d, 0x44, 0x7b, 0x72, 0x69, 0x60,
+  0x0e, 0x07, 0x1c, 0x15, 0x2a, 0x23, 0x38, 0x31, 0x46, 0x4f, 0x54, 0x5d,
+  0x62, 0x6b, 0x70, 0x79
+};
+
 /*===========================================================================*/
 /* Driver local functions.                                                   */
 /*===========================================================================*/
 
+/**
+ * @brief Calculate the MMC standard CRC-7 based on a lookup table.
+ *
+ * @param[in] crc       start value for CRC
+ * @param[in] buffer    pointer to data buffer
+ * @param[in] len       length of data
+ * @return              Calculated CRC
+ */
+static uint8_t crc7(uint8_t crc, const uint8_t *buffer, size_t len) {
+
+  while (len--)
+    crc = crc7_lookup_table[(crc << 1) ^ (*buffer++)];
+  return crc;
+}
+
 /**
  * @brief   Inserion monitor timer callback function.
  *
@@ -132,7 +175,9 @@ static void send_hdr(MMCDriver *mmcp, uint8_t cmd, uint32_t arg) {
   buf[2] = arg >> 16;
   buf[3] = arg >> 8;
   buf[4] = arg;
-  buf[5] = 0x95;        /* Valid for CMD0 ignored by other commands. */
+  /* Calculate CRC for command header, shift to right position, add stop bit.*/
+  buf[5] = ((crc7(0, buf, 5) & 0x7F) << 1) | 0x01;
+
   spiSend(mmcp->spip, 6, buf);
 }
 
@@ -665,8 +710,10 @@ bool_t mmcSequentialWrite(MMCDriver *mmcp, const uint8_t *buffer) {
   spiSend(mmcp->spip, MMC_SECTOR_SIZE, buffer);     /* Data.                */
   spiIgnore(mmcp->spip, 2);                         /* CRC ignored.         */
   spiReceive(mmcp->spip, 1, b);
-  if ((b[0] & 0x1F) == 0x05)
+  if ((b[0] & 0x1F) == 0x05) {
+    wait(mmcp);
     return FALSE;
+  }
 
   /* Error.*/
   spiUnselect(mmcp->spip);
@@ -699,10 +746,6 @@ bool_t mmcStopSequentialWrite(MMCDriver *mmcp) {
   }
   chSysUnlock();
 
-  /* Wait completion of the last write operation.*/
-  wait(mmcp);
-
-  /* Semd stop command.*/
   spiSend(mmcp->spip, sizeof(stop), stop);
   spiUnselect(mmcp->spip);
 
-- 
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