[RFC PATCH 4/5] 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 procedure.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 drivers/scsi/ufs/ufshcd-crypto.c | 24 ++++++++++++++++++------
 drivers/scsi/ufs/ufshcd.h        |  5 +++++
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd-crypto.c b/drivers/scsi/ufs/ufshcd-crypto.c
index 2c34beb47f8e0..4b9e4d5770643 100644
--- a/drivers/scsi/ufs/ufshcd-crypto.c
+++ b/drivers/scsi/ufs/ufshcd-crypto.c
@@ -117,15 +117,21 @@ static int ufshcd_crypto_cfg_entry_write_key(union ufs_crypto_cfg_entry *cfg,
 	return -EINVAL;
 }
 
-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;
 
 	pm_runtime_get_sync(hba->dev);
 	ufshcd_hold(hba, false);
+
+	if (hba->vops->program_key) {
+		err = hba->vops->program_key(hba, cfg, slot);
+		goto out;
+	}
+
 	/* Clear the dword 16 */
 	ufshcd_writel(hba, 0, slot_offset + 16 * sizeof(cfg->reg_val[0]));
 	/* Ensure that CFGE is cleared before programming the key */
@@ -145,15 +151,20 @@ static void ufshcd_program_key(struct ufs_hba *hba,
 	ufshcd_writel(hba, le32_to_cpu(cfg->reg_val[16]),
 		      slot_offset + 16 * sizeof(cfg->reg_val[0]));
 	wmb();
+	err = 0;
+out:
 	ufshcd_release(hba);
 	pm_runtime_put_sync(hba->dev);
+	return err;
 }
 
 static void ufshcd_clear_keyslot(struct ufs_hba *hba, int slot)
 {
 	union ufs_crypto_cfg_entry cfg = { 0 };
+	int err;
 
-	ufshcd_program_key(hba, &cfg, slot);
+	err = ufshcd_program_key(hba, &cfg, slot);
+	WARN_ON_ONCE(err);
 }
 
 /* Clear all keyslots at driver init time */
@@ -198,10 +209,11 @@ static int ufshcd_crypto_keyslot_program(struct keyslot_manager *ksm,
 	if (err)
 		return err;
 
-	ufshcd_program_key(hba, &cfg, slot);
+	err = ufshcd_program_key(hba, &cfg, slot);
 
 	memzero_explicit(&cfg, sizeof(cfg));
-	return 0;
+
+	return err;
 }
 
 static int ufshcd_crypto_keyslot_evict(struct keyslot_manager *ksm,
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index b6f0d08a98a8b..cd0969b93d070 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -280,6 +280,8 @@ struct ufs_pwr_mode_info {
 	struct ufs_pa_layer_attr info;
 };
 
+union ufs_crypto_cfg_entry;
+
 /**
  * struct ufs_hba_variant_ops - variant specific callbacks
  * @name: variant name
@@ -307,6 +309,7 @@ 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 an inline encryption key into a keyslot
  */
 struct ufs_hba_variant_ops {
 	const char *name;
@@ -336,6 +339,8 @@ 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  */
-- 
2.24.1