firmware: qcom: scm: add support for SHM bridge operations

SHM Bridge is a safety mechanism allowing to limit the amount of memory
shared between the kernel and the TrustZone to regions explicitly marked
as such.

Add low-level primitives for enabling SHM bridge support as well as
creating and destroying SHM bridges to qcom-scm.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Acked-by: Andrew Halaney <ahalaney@redhat.com>
Tested-by: Andrew Halaney <ahalaney@redhat.com> # sc8280xp-lenovo-thinkpad-x13s
Tested-by: Deepti Jaggi <quic_djaggi@quicinc.com> #sa8775p-ride
Reviewed-by: Elliot Berman <quic_eberman@quicinc.com>
Link: https://lore.kernel.org/r/20240527-shm-bridge-v10-10-ce7afaa58d3a@linaro.org
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

2 files changed, 63 insertions, 0 deletions

diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
index 43676a680de2..19950ec801c2 100644
--- a/drivers/firmware/qcom/qcom_scm.c
+++ b/drivers/firmware/qcom/qcom_scm.c
@@ -1343,6 +1343,66 @@ bool qcom_scm_lmh_dcvsh_available(void)
 }
 EXPORT_SYMBOL_GPL(qcom_scm_lmh_dcvsh_available);
 
+int qcom_scm_shm_bridge_enable(void)
+{
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_MP,
+		.cmd = QCOM_SCM_MP_SHM_BRIDGE_ENABLE,
+		.owner = ARM_SMCCC_OWNER_SIP
+	};
+
+	struct qcom_scm_res res;
+
+	if (!__qcom_scm_is_call_available(__scm->dev, QCOM_SCM_SVC_MP,
+					  QCOM_SCM_MP_SHM_BRIDGE_ENABLE))
+		return -EOPNOTSUPP;
+
+	return qcom_scm_call(__scm->dev, &desc, &res) ?: res.result[0];
+}
+EXPORT_SYMBOL_GPL(qcom_scm_shm_bridge_enable);
+
+int qcom_scm_shm_bridge_create(struct device *dev, u64 pfn_and_ns_perm_flags,
+			       u64 ipfn_and_s_perm_flags, u64 size_and_flags,
+			       u64 ns_vmids, u64 *handle)
+{
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_MP,
+		.cmd = QCOM_SCM_MP_SHM_BRIDGE_CREATE,
+		.owner = ARM_SMCCC_OWNER_SIP,
+		.args[0] = pfn_and_ns_perm_flags,
+		.args[1] = ipfn_and_s_perm_flags,
+		.args[2] = size_and_flags,
+		.args[3] = ns_vmids,
+		.arginfo = QCOM_SCM_ARGS(4, QCOM_SCM_VAL, QCOM_SCM_VAL,
+					 QCOM_SCM_VAL, QCOM_SCM_VAL),
+	};
+
+	struct qcom_scm_res res;
+	int ret;
+
+	ret = qcom_scm_call(__scm->dev, &desc, &res);
+
+	if (handle && !ret)
+		*handle = res.result[1];
+
+	return ret ?: res.result[0];
+}
+EXPORT_SYMBOL_GPL(qcom_scm_shm_bridge_create);
+
+int qcom_scm_shm_bridge_delete(struct device *dev, u64 handle)
+{
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_MP,
+		.cmd = QCOM_SCM_MP_SHM_BRIDGE_DELETE,
+		.owner = ARM_SMCCC_OWNER_SIP,
+		.args[0] = handle,
+		.arginfo = QCOM_SCM_ARGS(1, QCOM_SCM_VAL),
+	};
+
+	return qcom_scm_call(__scm->dev, &desc, NULL);
+}
+EXPORT_SYMBOL_GPL(qcom_scm_shm_bridge_delete);
+
 int qcom_scm_lmh_profile_change(u32 profile_id)
 {
 	struct qcom_scm_desc desc = {
diff --git a/drivers/firmware/qcom/qcom_scm.h b/drivers/firmware/qcom/qcom_scm.h
index 628f5efe0197..685b8f59e7a6 100644
--- a/drivers/firmware/qcom/qcom_scm.h
+++ b/drivers/firmware/qcom/qcom_scm.h
@@ -116,6 +116,9 @@ struct qcom_tzmem_pool *qcom_scm_get_tzmem_pool(void);
 #define QCOM_SCM_MP_IOMMU_SET_CP_POOL_SIZE	0x05
 #define QCOM_SCM_MP_VIDEO_VAR			0x08
 #define QCOM_SCM_MP_ASSIGN			0x16
+#define QCOM_SCM_MP_SHM_BRIDGE_ENABLE		0x1c
+#define QCOM_SCM_MP_SHM_BRIDGE_DELETE		0x1d
+#define QCOM_SCM_MP_SHM_BRIDGE_CREATE		0x1e
 
 #define QCOM_SCM_SVC_OCMEM		0x0f
 #define QCOM_SCM_OCMEM_LOCK_CMD		0x01