sd: sdhci: Implement basic vendor specific register support

The Linux kernel's IMX code now uses vendor specific commands.
This results in endless warnings when booting the Linux kernel.

sdhci-esdhc-imx 2194000.usdhc: esdhc_wait_for_card_clock_gate_off:
	card clock still not gate off in 100us!.

Implement support for the vendor specific command implemented in IMX hardware
to be able to avoid this warning.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Message-id: 20200603145258.195920-2-linux@roeck-us.net
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/sd/sdhci-internal.h

@@ -75,6 +75,7 @@
 #define SDHC_CMD_INHIBIT               0x00000001
 #define SDHC_DATA_INHIBIT              0x00000002
 #define SDHC_DAT_LINE_ACTIVE           0x00000004
+#define SDHC_IMX_CLOCK_GATE_OFF        0x00000080
 #define SDHC_DOING_WRITE               0x00000100
 #define SDHC_DOING_READ                0x00000200
 #define SDHC_SPACE_AVAILABLE           0x00000400
@@ -289,7 +290,10 @@ extern const VMStateDescription sdhci_vmstate;
 
 
 #define ESDHC_MIX_CTRL                  0x48
+
 #define ESDHC_VENDOR_SPEC               0xc0
+#define ESDHC_IMX_FRC_SDCLK_ON          (1 << 8)
+
 #define ESDHC_DLL_CTRL                  0x60
 
 #define ESDHC_TUNING_CTRL               0xcc
@@ -326,6 +330,7 @@ extern const VMStateDescription sdhci_vmstate;
 #define DEFINE_SDHCI_COMMON_PROPERTIES(_state) \
     DEFINE_PROP_UINT8("sd-spec-version", _state, sd_spec_version, 2), \
     DEFINE_PROP_UINT8("uhs", _state, uhs_mode, UHS_NOT_SUPPORTED), \
+    DEFINE_PROP_UINT8("vendor", _state, vendor, SDHCI_VENDOR_NONE), \
     \
     /* Capabilities registers provide information on supported
      * features of this specific host controller implementation */ \

hw/sd/sdhci.c

@@ -1569,11 +1569,13 @@ static uint64_t usdhc_read(void *opaque, hwaddr offset, unsigned size)
         }
         break;
 
+    case ESDHC_VENDOR_SPEC:
+        ret = s->vendor_spec;
+        break;
     case ESDHC_DLL_CTRL:
     case ESDHC_TUNE_CTRL_STATUS:
     case ESDHC_UNDOCUMENTED_REG27:
     case ESDHC_TUNING_CTRL:
-    case ESDHC_VENDOR_SPEC:
     case ESDHC_MIX_CTRL:
     case ESDHC_WTMK_LVL:
         ret = 0;
@@ -1596,7 +1598,21 @@ usdhc_write(void *opaque, hwaddr offset, uint64_t val, unsigned size)
     case ESDHC_UNDOCUMENTED_REG27:
     case ESDHC_TUNING_CTRL:
     case ESDHC_WTMK_LVL:
+        break;
+
     case ESDHC_VENDOR_SPEC:
+        s->vendor_spec = value;
+        switch (s->vendor) {
+        case SDHCI_VENDOR_IMX:
+            if (value & ESDHC_IMX_FRC_SDCLK_ON) {
+                s->prnsts &= ~SDHC_IMX_CLOCK_GATE_OFF;
+            } else {
+                s->prnsts |= SDHC_IMX_CLOCK_GATE_OFF;
+            }
+            break;
+        default:
+            break;
+        }
         break;
 
     case SDHC_HOSTCTL:

include/hw/sd/sdhci.h

@@ -74,6 +74,7 @@ typedef struct SDHCIState {
     uint16_t acmd12errsts; /* Auto CMD12 error status register */
     uint16_t hostctl2;     /* Host Control 2 */
     uint64_t admasysaddr;  /* ADMA System Address Register */
+    uint16_t vendor_spec;  /* Vendor specific register */
 
     /* Read-only registers */
     uint64_t capareg;      /* Capabilities Register */
@@ -96,8 +97,12 @@ typedef struct SDHCIState {
     uint32_t quirks;
     uint8_t sd_spec_version;
     uint8_t uhs_mode;
+    uint8_t vendor;        /* For vendor specific functionality */
 } SDHCIState;
 
+#define SDHCI_VENDOR_NONE       0
+#define SDHCI_VENDOR_IMX        1
+
 /*
  * Controller does not provide transfer-complete interrupt when not
  * busy.