[RFC PATCH v3 3/4] scsi: ufs: add program_key() variant op

[Eric Biggers <ebiggers@kernel.org>]

From: Eric Biggers <ebiggers@google.com>

On Snapdragon SoCs, the Linux kernel isn't permitted to directly access
the standard UFS crypto configuration registers.  Instead, programming
and evicting keys must be done through vendor-specific SMC calls.

To support this hardware, add a ->program_key() method to
'struct ufs_hba_variant_ops'.  This allows overriding the UFS standard
key programming / eviction procedure.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 drivers/scsi/ufs/ufshcd-crypto.c | 33 ++++++++++++++++++++------------
 drivers/scsi/ufs/ufshcd.h        |  3 +++
 2 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd-crypto.c b/drivers/scsi/ufs/ufshcd-crypto.c
index 37254472326a8..6b029ff2d037b 100644
--- a/drivers/scsi/ufs/ufshcd-crypto.c
+++ b/drivers/scsi/ufs/ufshcd-crypto.c
@@ -144,14 +144,20 @@ static blk_status_t ufshcd_crypto_cfg_entry_write_key(
 	return BLK_STS_IOERR;
 }
 
-static void ufshcd_program_key(struct ufs_hba *hba,
-			       const union ufs_crypto_cfg_entry *cfg,
-			       int slot)
+static int ufshcd_program_key(struct ufs_hba *hba,
+			      const union ufs_crypto_cfg_entry *cfg, int slot)
 {
 	int i;
 	u32 slot_offset = hba->crypto_cfg_register + slot * sizeof(*cfg);
+	int err = 0;
 
 	ufshcd_hold(hba, false);
+
+	if (hba->vops && hba->vops->program_key) {
+		err = hba->vops->program_key(hba, cfg, slot);
+		goto out;
+	}
+
 	/* Ensure that CFGE is cleared before programming the key */
 	ufshcd_writel(hba, 0, slot_offset + 16 * sizeof(cfg->reg_val[0]));
 	for (i = 0; i < 16; i++) {
@@ -164,23 +170,28 @@ static void ufshcd_program_key(struct ufs_hba *hba,
 	/* Dword 16 must be written last */
 	ufshcd_writel(hba, le32_to_cpu(cfg->reg_val[16]),
 		      slot_offset + 16 * sizeof(cfg->reg_val[0]));
+out:
 	ufshcd_release(hba);
+	return err;
 }
 
-static void ufshcd_clear_keyslot(struct ufs_hba *hba, int slot)
+static int ufshcd_clear_keyslot(struct ufs_hba *hba, int slot)
 {
 	union ufs_crypto_cfg_entry cfg = { 0 };
 
-	ufshcd_program_key(hba, &cfg, slot);
+	return ufshcd_program_key(hba, &cfg, slot);
 }
 
 /* Clear all keyslots at driver init time */
 static void ufshcd_clear_all_keyslots(struct ufs_hba *hba)
 {
 	int slot;
+	int err;
 
-	for (slot = 0; slot < ufshcd_num_keyslots(hba); slot++)
-		ufshcd_clear_keyslot(hba, slot);
+	for (slot = 0; slot < ufshcd_num_keyslots(hba); slot++) {
+		err = ufshcd_clear_keyslot(hba, slot);
+		WARN_ON_ONCE(err);
+	}
 }
 
 static blk_status_t ufshcd_crypto_keyslot_program(struct keyslot_manager *ksm,
@@ -216,10 +227,10 @@ static blk_status_t ufshcd_crypto_keyslot_program(struct keyslot_manager *ksm,
 	if (err)
 		return err;
 
-	ufshcd_program_key(hba, &cfg, slot);
+	err = errno_to_blk_status(ufshcd_program_key(hba, &cfg, slot));
 
 	memzero_explicit(&cfg, sizeof(cfg));
-	return BLK_STS_OK;
+	return err;
 }
 
 static int ufshcd_crypto_keyslot_evict(struct keyslot_manager *ksm,
@@ -236,9 +247,7 @@ static int ufshcd_crypto_keyslot_evict(struct keyslot_manager *ksm,
 	 * Clear the crypto cfg on the device. Clearing CFGE
 	 * might not be sufficient, so just clear the entire cfg.
 	 */
-	ufshcd_clear_keyslot(hba, slot);
-
-	return 0;
+	return ufshcd_clear_keyslot(hba, slot);
 }
 
 void ufshcd_crypto_enable(struct ufs_hba *hba)
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 78397864f9117..93ad978aa5dbd 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -306,6 +306,7 @@ struct ufs_pwr_mode_info {
  * @dbg_register_dump: used to dump controller debug information
  * @phy_initialization: used to initialize phys
  * @device_reset: called to issue a reset pulse on the UFS device
+ * @program_key: program or evict an inline encryption key
  */
 struct ufs_hba_variant_ops {
 	const char *name;
@@ -335,6 +336,8 @@ struct ufs_hba_variant_ops {
 	void	(*dbg_register_dump)(struct ufs_hba *hba);
 	int	(*phy_initialization)(struct ufs_hba *);
 	void	(*device_reset)(struct ufs_hba *hba);
+	int	(*program_key)(struct ufs_hba *hba,
+			       const union ufs_crypto_cfg_entry *cfg, int slot);
 };
 
 /* clock gating state  */
-- 
2.25.1