Using _cmd for _go_idle_state funciton

features/filesystem/sd/SDBlockDevice.cpp

@@ -148,9 +148,7 @@
 #include "mbed_debug.h"
 
 #define SD_COMMAND_TIMEOUT                       5000    /*!< Number of times to query card for correct result */
-#define SD_CMD0_GO_IDLE_STATE_RETRIES            3       /*!< Number of retries for sending CMDO*/
-#define SD_CMD0_GO_IDLE_STATE                    0x00    /*!< CMD0 code value */
-#define SD_CMD0_INVALID_RESPONSE_TIMEOUT         -1      /*!< CMD0 received invalid responses and timed out */
+#define SD_CMD0_GO_IDLE_STATE_RETRIES            5       /*!< Number of retries for sending CMDO */
 #define SD_DBG                                   1
 
 #define SD_BLOCK_DEVICE_ERROR_WOULD_BLOCK        -5001	/*!< operation would block */
@@ -251,9 +249,12 @@ SDBlockDevice::~SDBlockDevice()
 int SDBlockDevice::_initialise_card()
 {
     _dbg = SD_DBG;
+
+    // Initialize the SPI interface: Card by default is in SD mode
     _spi_init();
 
-    /* Transition from SD Card mode to SPI mode by sending CMD0 GO_IDLE_STATE command */
+    // The card is transitioned from SDCard mode to SPI mode by sending the
+    // CMD0 (GO_IDLE_STATE) command with CS asserted
     if (_go_idle_state() != R1_IDLE_STATE) {
         debug_if(_dbg, "No disk, or could not put SD card in to SPI idle state\n");
         return SD_BLOCK_DEVICE_ERROR_NO_DEVICE;
@@ -572,40 +573,21 @@ int SDBlockDevice::_cmd8() {
     _deselect();
     return -1; // timeout
 }
+uint32_t SDBlockDevice::_go_idle_state() {
+    uint32_t response;
 
-int SDBlockDevice::_go_idle_state() {
-    int cmd_arg = 0;    /* CMD0 argument is just "stuff bits" */
-    int ret = SD_CMD0_INVALID_RESPONSE_TIMEOUT;
-
-    _select();
     /* Reseting the MCU SPI master may not reset the on-board SDCard, in which
      * case when MCU power-on occurs the SDCard will resume operations as
      * though there was no reset. In this scenario the first CMD0 will
      * not be interpreted as a command and get lost. For some cards retrying
      * the command overcomes this situation. */
-    for (int num_retries = 0; ret != R1_IDLE_STATE && (num_retries < SD_CMD0_GO_IDLE_STATE_RETRIES); num_retries++) {
-        /* send a CMD0 */
-        _spi.write(0x40 | SD_CMD0_GO_IDLE_STATE);
-        _spi.write(cmd_arg >> 24);
-        _spi.write(cmd_arg >> 16);
-        _spi.write(cmd_arg >> 8);
-        _spi.write(cmd_arg >> 0);
-        _spi.write(0x95);
-
-        /* wait for the R1_IDLE_STATE response */
-        for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
-            int response = _spi.write(0xFF);
-            /* Explicitly check for the R1_IDLE_STATE response rather that most significant bit
-             * being 0 because invalid data can be returned. */
-            if ((response == R1_IDLE_STATE)) {
-                ret = response;
-                break;
-            }
-            wait_ms(1);
-        }
+    for (int i = 0; i < SD_CMD0_GO_IDLE_STATE_RETRIES; i++) {
+        _cmd(CMD0_GO_IDLE_STATE, 0, &response);
+        if (R1_IDLE_STATE == response)
+            break;
+        wait_ms(1);
     }
-    _deselect();
-    return ret;
+    return response;
 }
 
 int SDBlockDevice::_read(uint8_t *buffer, uint32_t length) {
@@ -733,7 +715,6 @@ void SDBlockDevice::_spi_init() {
     _spi.unlock();
 }
 
-
 void SDBlockDevice::_select() {
     _spi.lock();
     _cs = 0;

features/filesystem/sd/SDBlockDevice.h

@@ -179,11 +179,10 @@ class SDBlockDevice : public BlockDevice {
      *  "SPI Startup" section of the comments at the head of the
      *  implementation file for further details and specification references.
      *
-     *  @return         -1 if an error occurred e.g. a valid response was not
-     *                  received. Otherwise R1_IDLE_STATE (0x1), the successful
-     *                  response from CMD0.
+     *  @return         Response form the card. R1_IDLE_STATE (0x1), the successful
+     *                  response from CMD0. R1_XXX_XXX for more response
      */
-    int _go_idle_state();
+    uint32_t _go_idle_state();
     int _initialise_card();
     int _initialise_card_v1();
     int _initialise_card_v2();