[incubator-nuttx] 02/05: driver/mmcsd: add option to support SD/MMC PHYs that only run in 4-bit mode

[xi...@apache.org]

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xiaoxiang pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/incubator-nuttx.git

commit 163e3fd93cd661d97cc38aaadc0210554fe2f0f8
Author: Richard Tucker <ri...@motec.com.au>
AuthorDate: Thu Mar 24 14:56:40 2022 +1100

    driver/mmcsd: add option to support SD/MMC PHYs that only run in 4-bit mode
---
 drivers/mmcsd/mmcsd_sdio.c | 29 ++++++++++++++++++++++++-----
 include/nuttx/sdio.h       |  1 +
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/drivers/mmcsd/mmcsd_sdio.c b/drivers/mmcsd/mmcsd_sdio.c
index d0fa5c4..bcb8e77 100644
--- a/drivers/mmcsd/mmcsd_sdio.c
+++ b/drivers/mmcsd/mmcsd_sdio.c
@@ -2881,6 +2881,22 @@ static int mmcsd_sdinitialize(FAR struct mmcsd_state_s *priv)
   SDIO_CLOCK(priv->dev, CLOCK_SD_TRANSFER_1BIT);
   nxsig_usleep(MMCSD_CLK_DELAY);
 
+  /* If the hardware only supports 4-bit transfer mode then we forced to
+   * attempt to setup the card in this mode before checking the SCR register.
+   */
+
+  if ((priv->caps & SDIO_CAPS_4BIT_ONLY) != 0)
+    {
+      /* Select width (4-bit) bus operation */
+
+      priv->buswidth = 4;
+      ret = mmcsd_widebus(priv);
+      if (ret != OK)
+        {
+          ferr("ERROR: Failed to set wide bus operation: %d\n", ret);
+        }
+    }
+
   /* Get the SD card Configuration Register (SCR).  We need this now because
    * that configuration register contains the indication whether or not
    * this card supports wide bus operation.
@@ -2895,12 +2911,15 @@ static int mmcsd_sdinitialize(FAR struct mmcsd_state_s *priv)
 
   mmcsd_decode_scr(priv, scr);
 
-  /* Select width (4-bit) bus operation (if the card supports it) */
-
-  ret = mmcsd_widebus(priv);
-  if (ret != OK)
+  if ((priv->caps & SDIO_CAPS_4BIT_ONLY) == 0)
     {
-      ferr("ERROR: Failed to set wide bus operation: %d\n", ret);
+      /* Select width (4-bit) bus operation (if the card supports it) */
+
+      ret = mmcsd_widebus(priv);
+      if (ret != OK)
+        {
+          ferr("ERROR: Failed to set wide bus operation: %d\n", ret);
+        }
     }
 
   /* TODO: If wide-bus selected, then send CMD6 to see if the card supports
diff --git a/include/nuttx/sdio.h b/include/nuttx/sdio.h
index 9fa97c8..b32f617 100644
--- a/include/nuttx/sdio.h
+++ b/include/nuttx/sdio.h
@@ -477,6 +477,7 @@
 #define SDIO_CAPS_DMABEFOREWRITE  0x04 /* Bit 2=1: Executes DMA before write command */
 #define SDIO_CAPS_4BIT            0x08 /* Bit 3=1: Supports 4 bit operation */
 #define SDIO_CAPS_8BIT            0x10 /* Bit 4=1: Supports 8 bit operation */
+#define SDIO_CAPS_4BIT_ONLY       0x20 /* Bit 5=1: Supports 4-bit only operation */
 
 /****************************************************************************
  * Name: SDIO_STATUS