mmc: core: Add capability to avoid 3.3V signaling

Some SD host controllers cannot handle extended use of 3.3V signaling.
To accommodate these controllers, add a capability that requires us to
negotiate the voltage down from 3.3V during card initialization.

Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
Signed-off-by: Jennifer Dahm <jennifer.dahm@ni.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

3 files changed, 24 insertions, 0 deletions

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 6f8ebd6..915b58f 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1830,6 +1830,14 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
 		}
 	}
 
+	if (host->caps2 & MMC_CAP2_AVOID_3_3V &&
+	    host->ios.signal_voltage == MMC_SIGNAL_VOLTAGE_330) {
+		pr_err("%s: Host failed to negotiate down from 3.3V\n",
+			mmc_hostname(host));
+		err = -EINVAL;
+		goto free_card;
+	}
+
 	if (!oldcard)
 		host->card = card;
 
diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index baf3d5d..7f87a53 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -1058,6 +1058,14 @@ retry:
 			mmc_set_bus_width(host, MMC_BUS_WIDTH_4);
 		}
 	}
+
+	if (host->caps2 & MMC_CAP2_AVOID_3_3V &&
+	    host->ios.signal_voltage == MMC_SIGNAL_VOLTAGE_330) {
+		pr_err("%s: Host failed to negotiate down from 3.3V\n",
+			mmc_hostname(host));
+		err = -EINVAL;
+		goto free_card;
+	}
 done:
 	host->card = card;
 	return 0;
diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
index 24b510b..87e53a7 100644
--- a/drivers/mmc/core/sdio.c
+++ b/drivers/mmc/core/sdio.c
@@ -792,6 +792,14 @@ try_again:
 		if (err)
 			goto remove;
 	}
+
+	if (host->caps2 & MMC_CAP2_AVOID_3_3V &&
+	    host->ios.signal_voltage == MMC_SIGNAL_VOLTAGE_330) {
+		pr_err("%s: Host failed to negotiate down from 3.3V\n",
+			mmc_hostname(host));
+		err = -EINVAL;
+		goto remove;
+	}
 finish:
 	if (!oldcard)
 		host->card = card;