Capability register is read-only.

Since we allow instances to clear/set extra bits, log when
read-only bits normally set by hardware are cleared at
board level.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 include/hw/sd/sdhci.h | 5 +++++
 hw/sd/sdhci.c         | 6 ++++++
 2 files changed, 11 insertions(+)

diff --git a/include/hw/sd/sdhci.h b/include/hw/sd/sdhci.h
index a91cda16cbe..15ef3a07b54 100644
--- a/include/hw/sd/sdhci.h
+++ b/include/hw/sd/sdhci.h
@@ -116,6 +116,11 @@ typedef struct SDHCIClass {
     const MemoryRegionOps *io_ops;
     uint32_t quirks;
     uint64_t iomem_size;
+
+    /* Read-only registers */
+    struct {
+        uint64_t capareg;
+    } ro;
 } SDHCIClass;
 
 /*
diff --git a/hw/sd/sdhci.c b/hw/sd/sdhci.c
index f2bb612c665..9708b52f850 100644
--- a/hw/sd/sdhci.c
+++ b/hw/sd/sdhci.c
@@ -73,6 +73,7 @@ static bool sdhci_check_capab_freq_range(SDHCIState *s, const char *desc,
 
 static void sdhci_check_capareg(SDHCIState *s, Error **errp)
 {
+    SDHCIClass *sc = SYSBUS_SDHCI_GET_CLASS(s);
     uint64_t msk = s->capareg;
     uint32_t val;
     bool y;
@@ -208,6 +209,11 @@ static void sdhci_check_capareg(SDHCIState *s, Error **errp)
         qemu_log_mask(LOG_UNIMP,
                       "SDHCI: unknown CAPAB mask: 0x%016" PRIx64 "\n", msk);
     }
+    msk = sc->ro.capareg & ~s->capareg;
+    if (msk) {
+        qemu_log_mask(LOG_UNIMP,
+                      "SDHCI: ignored CAPAB mask: 0x%016" PRIx64 "\n", msk);
+    }
 }
 
 static uint8_t sdhci_slotint(SDHCIState *s)
-- 
2.47.1