[nrf noup] secure_fw: platform: Add system off service

Add the tfm_platform_system_off APIs in a similar manner
as the existing tfm_platform_system_reset. This API
should enable implementations to allow setting the
TF-M to the lowest power mode using their own
HAL APIs.

Right now this will work for isolation level 1 (SFN mode).
In the IPC mode there is a need for better TF-M support for
this. There is a discussion with the TF-M owners to add logic
to TF-M so that it can inform all the partitions in order
to make sure that it is safe to go to system off mode.

Signed-off-by: Georgios Vasilakis <georgios.vasilakis@nordicsemi.no>

Author: Vge0rge

interface/include/tfm_platform_api.h

@@ -27,6 +27,7 @@ extern "C" {
 #define TFM_PLATFORM_API_ID_NV_INCREMENT  (1011)
 #define TFM_PLATFORM_API_ID_SYSTEM_RESET  (1012)
 #define TFM_PLATFORM_API_ID_IOCTL         (1013)
+#define TFM_PLATFORM_API_ID_SYSTEM_OFF    (1014)
 
 /*!
  * \enum tfm_platform_err_t
@@ -53,6 +54,14 @@ typedef int32_t tfm_platform_ioctl_req_t;
  */
 enum tfm_platform_err_t tfm_platform_system_reset(void);
 
+/*!
+ * \brief System off function to move the system to the lowest power state
+ *
+ * \return On success the processor will go to system off, in case of error it returns
+ *         values as specified by the \ref tfm_platform_err_t
+ */
+enum tfm_platform_err_t tfm_platform_system_off(void);
+
 /*!
  * \brief Performs a platform-specific service
  *

interface/src/tfm_platform_api.c

@@ -26,6 +26,21 @@ enum tfm_platform_err_t tfm_platform_system_reset(void)
 
 }
 
+enum tfm_platform_err_t tfm_platform_system_off(void)
+{
+    psa_status_t status = PSA_ERROR_CONNECTION_REFUSED;
+
+    status = psa_call(TFM_PLATFORM_SERVICE_HANDLE,
+                      TFM_PLATFORM_API_ID_SYSTEM_OFF,
+                      NULL, 0, NULL, 0);
+
+    if (status < PSA_SUCCESS) {
+        return TFM_PLATFORM_ERR_SYSTEM_ERROR;
+    } else {
+        return (enum tfm_platform_err_t)status;
+    }
+}
+
 enum tfm_platform_err_t
 tfm_platform_ioctl(tfm_platform_ioctl_req_t request,
                    psa_invec *input, psa_outvec *output)

platform/ext/target/nordic_nrf/common/core/CMakeLists.txt

@@ -158,6 +158,18 @@ if(TFM_SPM_LOG_RAW_ENABLED)
     )
 endif()
 
+if(TFM_NRF_SYSTEM_OFF_SERVICE)
+    target_sources(platform_s
+        PRIVATE
+            ${HAL_NORDIC_PATH}/nrfx/helpers/nrfx_ram_ctrl.c
+    )
+
+    target_compile_definitions(platform_s
+        PUBLIC
+            TFM_NRF_SYSTEM_OFF_SERVICE
+    )
+endif()
+
 target_compile_options(platform_s
     PUBLIC
         ${COMPILER_CMSE_FLAG}

platform/include/tfm_platform_system.h

@@ -28,6 +28,14 @@ extern "C" {
 TFM_LINK_SET_RO_IN_PARTITION_SECTION("TFM_SP_PLATFORM", "PSA-ROT")
 void tfm_platform_hal_system_reset(void);
 
+/**
+ * \brief Set system power state to off.
+ *
+ * \details Requests the system to enter a low-power state.
+ */
+TFM_LINK_SET_RO_IN_PARTITION_SECTION("TFM_SP_PLATFORM", "PSA-ROT")
+enum tfm_platform_err_t tfm_platform_hal_system_off(void);
+
 /*!
  * \brief Performs a platform-specific service
  *

secure_fw/partitions/platform/platform_sp.c

@@ -39,6 +39,24 @@ enum tfm_platform_err_t platform_sp_system_reset(void)
     return TFM_PLATFORM_ERR_SUCCESS;
 }
 
+#if TFM_NRF_SYSTEM_OFF_SERVICE
+enum tfm_platform_err_t platform_sp_system_off(void)
+{
+    /* FIXME: The system off functionality is only supported in isolation
+     *        level 1.
+     */
+
+    return tfm_platform_hal_system_off();
+}
+
+static psa_status_t platform_sp_system_off_psa_api(const psa_msg_t *msg)
+{
+    (void)msg; /* unused parameter */
+
+    return platform_sp_system_off();
+}
+#endif /* TFM_NRF_SYSTEM_OFF_SERVICE */
+
 static psa_status_t platform_sp_system_reset_psa_api(const psa_msg_t *msg)
 {
     (void)msg; /* unused parameter */
@@ -225,6 +243,10 @@ psa_status_t tfm_platform_service_sfn(const psa_msg_t *msg)
 #endif /* PLATFORM_NV_COUNTER_MODULE_DISABLED */
     case TFM_PLATFORM_API_ID_SYSTEM_RESET:
         return platform_sp_system_reset_psa_api(msg);
+#if TFM_NRF_SYSTEM_OFF_SERVICE
+    case TFM_PLATFORM_API_ID_SYSTEM_OFF:
+        return platform_sp_system_off_psa_api(msg);
+#endif /* TFM_NRF_SYSTEM_OFF_SERVICE */
     case TFM_PLATFORM_API_ID_IOCTL:
         return platform_sp_ioctl_psa_api(msg);
     default: