[PATCH v8 05/12] media: iris: Enable Secure PAS support with IOMMU managed by Linux

[Vishnu Reddy <busanna.reddy@oss.qualcomm.com>]

From: Mukesh Ojha <mukesh.ojha@oss.qualcomm.com>

On platforms where a hypervisor is present, all Secure Monitor Calls
(SMC) are intercepted. For qcom_scm_pas_auth_and_reset(), the hypervisor
registers a Shared Memory (SHM) bridge over the Peripheral Image Loader
(PIL) memory region so that TrustZone (TZ) can access it, forwards the
authentication SMC to TZ, and upon return maps the PIL region and
triggers the co-processor bring-up sequence:

HLOS -> Hypervisor(SHM setup) -> TZ(auth) -> Hypervisor(map+reset) -> IRIS

On platforms without a hypervisor, Linux drives these steps directly.
The SHM bridge infrastructure required for this is already upstream [1].

To isolate firmware memory in its own Input-Output Memory Management
Unit (IOMMU) context, a dedicated stream ID (SID) is required, tied to
the firmware function ID. This SID is specified via the iommu-map
property in the device tree using the firmware function ID as the lookup
key. A firmware device is created and mapped to this SID.

The presence of a SID mapped to the firmware device via iommu-map is
used to detect whether a hypervisor is absent: when the firmware device
has a SID mapped, Linux manages the IOMMU directly; when no SID is
mapped, a hypervisor is assumed to be present and these steps are
skipped.

Extend the Iris driver to support Secure Peripheral Authentication
Service (PAS) on platforms where Linux manages the IOMMU, by creating
the firmware context device and performing the necessary IOMMU mapping
when the firmware device SID is present.

[1] https://lore.kernel.org/lkml/20260105-kvmrprocv10-v10-0-022e96815380
@oss.qualcomm.com/

Reviewed-by: Vishnu Reddy <busanna.reddy@oss.qualcomm.com>
Co-developed-by: Vikash Garodia <vikash.garodia@oss.qualcomm.com>
Signed-off-by: Vikash Garodia <vikash.garodia@oss.qualcomm.com>
Signed-off-by: Mukesh Ojha <mukesh.ojha@oss.qualcomm.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Link: https://lore.kernel.org/lkml/20260105-kvmrprocv10-v10-0-022e96815380@oss.qualcomm.com/
Signed-off-by: Vishnu Reddy <busanna.reddy@oss.qualcomm.com>
---
 drivers/media/platform/qcom/iris/iris_core.h     |  4 ++
 drivers/media/platform/qcom/iris/iris_firmware.c | 69 ++++++++++++++++++++----
 2 files changed, 62 insertions(+), 11 deletions(-)

diff --git a/drivers/media/platform/qcom/iris/iris_core.h b/drivers/media/platform/qcom/iris/iris_core.h
index 24da60448cf2..2edba569fa25 100644
--- a/drivers/media/platform/qcom/iris/iris_core.h
+++ b/drivers/media/platform/qcom/iris/iris_core.h
@@ -36,6 +36,8 @@ struct qcom_ubwc_cfg_data;
  * struct iris_core - holds core parameters valid for all instances
  *
  * @dev: reference to device structure
+ * @fw_dev: reference to the context bank device used for firmware load
+ * @pas_ctx: SCM PAS context for authenticated firmware load and shutdown
  * @reg_base: IO memory base address
  * @irq: iris irq
  * @v4l2_dev: a holder for v4l2 device structure
@@ -81,6 +83,8 @@ struct qcom_ubwc_cfg_data;
 
 struct iris_core {
 	struct device				*dev;
+	struct device				*fw_dev;
+	struct qcom_scm_pas_context		*pas_ctx;
 	void __iomem				*reg_base;
 	int					irq;
 	struct v4l2_device			v4l2_dev;
diff --git a/drivers/media/platform/qcom/iris/iris_firmware.c b/drivers/media/platform/qcom/iris/iris_firmware.c
index 1a476146d758..07b3ade88777 100644
--- a/drivers/media/platform/qcom/iris/iris_firmware.c
+++ b/drivers/media/platform/qcom/iris/iris_firmware.c
@@ -5,6 +5,7 @@
 
 #include <linux/firmware.h>
 #include <linux/firmware/qcom/qcom_scm.h>
+#include <linux/iommu.h>
 #include <linux/of_address.h>
 #include <linux/of_reserved_mem.h>
 #include <linux/soc/qcom/mdt_loader.h>
@@ -15,11 +16,13 @@
 #define IRIS_PAS_ID				9
 
 #define MAX_FIRMWARE_NAME_SIZE	128
+#define IRIS_FW_START_ADDR	0
 
 static int iris_load_fw_to_memory(struct iris_core *core, const char *fw_name)
 {
+	struct device *fw_dev = core->fw_dev ? core->fw_dev : core->dev;
 	const struct firmware *firmware = NULL;
-	struct device *dev = core->dev;
+	struct iommu_domain *domain;
 	struct resource res;
 	phys_addr_t mem_phys;
 	size_t res_size;
@@ -30,14 +33,21 @@ static int iris_load_fw_to_memory(struct iris_core *core, const char *fw_name)
 	if (strlen(fw_name) >= MAX_FIRMWARE_NAME_SIZE - 4)
 		return -EINVAL;
 
-	ret = of_reserved_mem_region_to_resource(dev->of_node, 0, &res);
+	ret = of_reserved_mem_region_to_resource(core->dev->of_node, 0, &res);
 	if (ret)
 		return ret;
 
 	mem_phys = res.start;
 	res_size = resource_size(&res);
 
-	ret = request_firmware(&firmware, fw_name, dev);
+	if (!core->pas_ctx) {
+		core->pas_ctx = devm_qcom_scm_pas_context_alloc(core->dev, IRIS_PAS_ID,
+								mem_phys, res_size);
+		if (IS_ERR(core->pas_ctx))
+			return PTR_ERR(core->pas_ctx);
+	}
+
+	ret = request_firmware(&firmware, fw_name, fw_dev);
 	if (ret)
 		return ret;
 
@@ -53,9 +63,23 @@ static int iris_load_fw_to_memory(struct iris_core *core, const char *fw_name)
 		goto err_release_fw;
 	}
 
-	ret = qcom_mdt_load(dev, firmware, fw_name,
-			    IRIS_PAS_ID, mem_virt, mem_phys, res_size, NULL);
+	core->pas_ctx->use_tzmem = !!core->fw_dev;
+	ret = qcom_mdt_pas_load(core->pas_ctx, firmware, fw_name, mem_virt, NULL);
+	if (ret)
+		goto err_mem_unmap;
+
+	if (core->pas_ctx->use_tzmem) {
+		domain = iommu_get_domain_for_dev(fw_dev);
+		if (!domain) {
+			ret = -ENODEV;
+			goto err_mem_unmap;
+		}
+
+		ret = iommu_map(domain, IRIS_FW_START_ADDR, mem_phys, res_size,
+				IOMMU_READ | IOMMU_WRITE | IOMMU_PRIV, GFP_KERNEL);
+	}
 
+err_mem_unmap:
 	memunmap(mem_virt);
 err_release_fw:
 	release_firmware(firmware);
@@ -63,6 +87,18 @@ static int iris_load_fw_to_memory(struct iris_core *core, const char *fw_name)
 	return ret;
 }
 
+static void iris_fw_iommu_unmap(struct iris_core *core)
+{
+	struct iommu_domain *domain;
+
+	if (!core->pas_ctx->use_tzmem)
+		return;
+
+	domain = iommu_get_domain_for_dev(core->fw_dev);
+	if (domain)
+		iommu_unmap(domain, IRIS_FW_START_ADDR, core->pas_ctx->mem_size);
+}
+
 int iris_fw_load(struct iris_core *core)
 {
 	const struct tz_cp_config *cp_config;
@@ -77,13 +113,13 @@ int iris_fw_load(struct iris_core *core)
 	ret = iris_load_fw_to_memory(core, fwpath);
 	if (ret) {
 		dev_err(core->dev, "firmware download failed\n");
-		return -ENOMEM;
+		return ret;
 	}
 
-	ret = qcom_scm_pas_auth_and_reset(IRIS_PAS_ID);
+	ret = qcom_scm_pas_prepare_and_auth_reset(core->pas_ctx);
 	if (ret)  {
 		dev_err(core->dev, "auth and reset failed: %d\n", ret);
-		return ret;
+		goto err_unmap;
 	}
 
 	for (i = 0; i < core->iris_platform_data->tz_cp_config_data_size; i++) {
@@ -94,17 +130,28 @@ int iris_fw_load(struct iris_core *core)
 						     cp_config->cp_nonpixel_size);
 		if (ret) {
 			dev_err(core->dev, "qcom_scm_mem_protect_video_var failed: %d\n", ret);
-			qcom_scm_pas_shutdown(IRIS_PAS_ID);
-			return ret;
+			goto err_pas_shutdown;
 		}
 	}
 
+	return 0;
+
+err_pas_shutdown:
+	qcom_scm_pas_shutdown(core->pas_ctx->pas_id);
+err_unmap:
+	iris_fw_iommu_unmap(core);
+
 	return ret;
 }
 
 int iris_fw_unload(struct iris_core *core)
 {
-	return qcom_scm_pas_shutdown(IRIS_PAS_ID);
+	int ret;
+
+	ret = qcom_scm_pas_shutdown(core->pas_ctx->pas_id);
+	iris_fw_iommu_unmap(core);
+
+	return ret;
 }
 
 int iris_set_hw_state(struct iris_core *core, bool resume)

-- 
2.34.1