[PATCH v2 1/3] firmware: qcom: pas: Add optional video memory protection op

[Sumit Garg <sumit.garg@kernel.org>]

From: Sumit Garg <sumit.garg@oss.qualcomm.com>

qcom_scm_mem_protect_video_var() is only serviced by the SCM backend.
Other PAS backends, e.g. OP-TEE, own secure memory protection and don't
implement such a call.

Add an optional mem_protect_video_var() PAS op along with a generic
qcom_pas_mem_protect_video_var() wrapper so that clients stay agnostic
of the active backend. The SCM backend maps it to the existing SCM call
while backends leaving it unset turn it into a no-op.

Signed-off-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
---
 drivers/firmware/qcom/qcom_pas.c       | 27 +++++++++++++++++++++++++++
 drivers/firmware/qcom/qcom_pas.h       |  5 +++++
 drivers/firmware/qcom/qcom_scm.c       | 10 ++++++++++
 include/linux/firmware/qcom/qcom_pas.h |  2 ++
 4 files changed, 44 insertions(+)

diff --git a/drivers/firmware/qcom/qcom_pas.c b/drivers/firmware/qcom/qcom_pas.c
index 24485dd0fa10..d478171e4697 100644
--- a/drivers/firmware/qcom/qcom_pas.c
+++ b/drivers/firmware/qcom/qcom_pas.c
@@ -237,6 +237,33 @@ int qcom_pas_shutdown(u32 pas_id)
 }
 EXPORT_SYMBOL_GPL(qcom_pas_shutdown);
 
+/**
+ * qcom_pas_mem_protect_video_var() - Set up video content protection ranges
+ * @cp_start:		content protection region start
+ * @cp_size:		content protection region size
+ * @cp_nonpixel_start:	non-pixel region start
+ * @cp_nonpixel_size:	non-pixel region size
+ *
+ * Backends that manage secure memory protection on their own do not
+ * implement this operation, in which case it is a no-op.
+ *
+ * Return: 0 on success.
+ */
+int qcom_pas_mem_protect_video_var(u32 cp_start, u32 cp_size,
+				   u32 cp_nonpixel_start, u32 cp_nonpixel_size)
+{
+	if (!ops_ptr)
+		return -ENODEV;
+
+	if (!ops_ptr->mem_protect_video_var)
+		return 0;
+
+	return ops_ptr->mem_protect_video_var(ops_ptr->dev, cp_start, cp_size,
+					      cp_nonpixel_start,
+					      cp_nonpixel_size);
+}
+EXPORT_SYMBOL_GPL(qcom_pas_mem_protect_video_var);
+
 /**
  * qcom_pas_supported() - Check if the peripheral authentication service is
  *			  supported for the given peripheral
diff --git a/drivers/firmware/qcom/qcom_pas.h b/drivers/firmware/qcom/qcom_pas.h
index 8643e2760602..481343669e1d 100644
--- a/drivers/firmware/qcom/qcom_pas.h
+++ b/drivers/firmware/qcom/qcom_pas.h
@@ -22,6 +22,8 @@ struct device;
  *				callback.
  * @set_remote_state:		Peripheral set remote state callback.
  * @shutdown:			Peripheral shutdown callback.
+ * @mem_protect_video_var:	Optional video secure memory protection callback.
+ *				Backends that do not need it leave it unset.
  * @metadata_release:		Image metadata release callback.
  */
 struct qcom_pas_ops {
@@ -40,6 +42,9 @@ struct qcom_pas_ops {
 	int (*auth_and_reset)(struct device *dev, u32 pas_id);
 	int (*set_remote_state)(struct device *dev, u32 state, u32 pas_id);
 	int (*shutdown)(struct device *dev, u32 pas_id);
+	int (*mem_protect_video_var)(struct device *dev, u32 cp_start,
+				     u32 cp_size, u32 cp_nonpixel_start,
+				     u32 cp_nonpixel_size);
 	void (*metadata_release)(struct device *dev,
 				 struct qcom_pas_context *ctx);
 };
diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
index 43e250faea75..5445c1aa14cc 100644
--- a/drivers/firmware/qcom/qcom_scm.c
+++ b/drivers/firmware/qcom/qcom_scm.c
@@ -981,6 +981,15 @@ static bool qcom_scm_pas_supported(struct device *dev, u32 pas_id)
 	return ret ? false : !!res.result[0];
 }
 
+static int qcom_scm_pas_mem_protect_video_var(struct device *dev, u32 cp_start,
+					      u32 cp_size, u32 cp_nonpixel_start,
+					      u32 cp_nonpixel_size)
+{
+	return qcom_scm_mem_protect_video_var(cp_start, cp_size,
+					      cp_nonpixel_start,
+					      cp_nonpixel_size);
+}
+
 static struct qcom_pas_ops qcom_pas_ops_scm = {
 	.drv_name		= "qcom_scm",
 	.supported		= qcom_scm_pas_supported,
@@ -991,6 +1000,7 @@ static struct qcom_pas_ops qcom_pas_ops_scm = {
 	.prepare_and_auth_reset	= qcom_scm_pas_prepare_and_auth_reset,
 	.set_remote_state	= qcom_scm_pas_set_remote_state,
 	.shutdown		= qcom_scm_pas_shutdown,
+	.mem_protect_video_var	= qcom_scm_pas_mem_protect_video_var,
 	.metadata_release	= qcom_scm_pas_metadata_release,
 };
 
diff --git a/include/linux/firmware/qcom/qcom_pas.h b/include/linux/firmware/qcom/qcom_pas.h
index fb2ec3be6a16..bfd4a9e5a705 100644
--- a/include/linux/firmware/qcom/qcom_pas.h
+++ b/include/linux/firmware/qcom/qcom_pas.h
@@ -49,6 +49,8 @@ int qcom_pas_auth_and_reset(u32 pas_id);
 int qcom_pas_prepare_and_auth_reset(struct qcom_pas_context *ctx);
 int qcom_pas_set_remote_state(u32 state, u32 pas_id);
 int qcom_pas_shutdown(u32 pas_id);
+int qcom_pas_mem_protect_video_var(u32 cp_start, u32 cp_size,
+				   u32 cp_nonpixel_start, u32 cp_nonpixel_size);
 bool qcom_pas_supported(u32 pas_id);
 void qcom_pas_metadata_release(struct qcom_pas_context *ctx);
 

-- 
2.43.0