mmc: cqhci: add support for inline encryption

Add support for eMMC inline encryption using the blk-crypto framework
(Documentation/block/inline-encryption.rst).

eMMC inline encryption support is specified by the upcoming JEDEC eMMC
v5.2 specification.  It is only specified for the CQ interface, not the
non-CQ interface.  Although the eMMC v5.2 specification hasn't been
officially released yet, the crypto support was already agreed on
several years ago, and it was already implemented by at least two major
hardware vendors.  Lots of hardware in the field already supports and
uses it, e.g. Snapdragon 630 to give one example.

eMMC inline encryption support is very similar to the UFS inline
encryption support which was standardized in the UFS v2.1 specification
and was already upstreamed.  The only major difference is that eMMC
limits data unit numbers to 32 bits, unlike UFS's 64 bits.

Like we did with UFS, make the crypto support opt-in by individual
drivers; don't enable it automatically whenever the hardware declares
crypto support.  This is necessary because in every case we've seen,
some extra vendor-specific logic is needed to use the crypto support.

Co-developed-by: Satya Tangirala <satyat@google.com>
Signed-off-by: Satya Tangirala <satyat@google.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Satya Tangirala <satyat@google.com>
Reviewed-and-tested-by: Peng Zhou <peng.zhou@mediatek.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20210125183810.198008-5-ebiggers@kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

1 files changed, 47 insertions, 0 deletions

diff --git a/drivers/mmc/host/cqhci-crypto.h b/drivers/mmc/host/cqhci-crypto.h
new file mode 100644
index 000000000000..60b58ee0e625
--- /dev/null
+++ b/drivers/mmc/host/cqhci-crypto.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * CQHCI crypto engine (inline encryption) support
+ *
+ * Copyright 2020 Google LLC
+ */
+
+#ifndef LINUX_MMC_CQHCI_CRYPTO_H
+#define LINUX_MMC_CQHCI_CRYPTO_H
+
+#include <linux/mmc/host.h>
+
+#include "cqhci.h"
+
+#ifdef CONFIG_MMC_CRYPTO
+
+int cqhci_crypto_init(struct cqhci_host *host);
+
+/*
+ * Returns the crypto bits that should be set in bits 64-127 of the
+ * task descriptor.
+ */
+static inline u64 cqhci_crypto_prep_task_desc(struct mmc_request *mrq)
+{
+	if (!mrq->crypto_enabled)
+		return 0;
+
+	return CQHCI_CRYPTO_ENABLE_BIT |
+	       CQHCI_CRYPTO_KEYSLOT(mrq->crypto_key_slot) |
+	       mrq->data_unit_num;
+}
+
+#else /* CONFIG_MMC_CRYPTO */
+
+static inline int cqhci_crypto_init(struct cqhci_host *host)
+{
+	return 0;
+}
+
+static inline u64 cqhci_crypto_prep_task_desc(struct mmc_request *mrq)
+{
+	return 0;
+}
+
+#endif /* !CONFIG_MMC_CRYPTO */
+
+#endif /* LINUX_MMC_CQHCI_CRYPTO_H */