Send power management events to the Trusted OS (TLK)

This patch adds PM handlers to TLKD for the system suspend/resume and
system poweroff/reset cases. TLK expects all SMCs through a single
handler, which then fork out into multiple handlers depending on the
SMC. We tap into the same single entrypoint by restoring the S-EL1
context before passing the PM event via register 'x0'. On completion
of the PM event, TLK sends a completion SMC and TLKD then moves on
with the PM process.
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>

include/bl32/payloads/tlk.h

@@ -43,6 +43,9 @@
 #define TLK_REGISTER_LOGBUF	TLK_TOS_STD_FID(0x1)
 #define TLK_REGISTER_REQBUF	TLK_TOS_STD_FID(0x2)
 #define TLK_RESUME_FID		TLK_TOS_STD_FID(0x100)
+#define TLK_SYSTEM_SUSPEND	TLK_TOS_STD_FID(0xE001)
+#define TLK_SYSTEM_RESUME	TLK_TOS_STD_FID(0xE002)
+#define TLK_SYSTEM_OFF		TLK_TOS_STD_FID(0xE003)
 
 /*
  * SMC function IDs that TLK uses to signal various forms of completions
@@ -52,6 +55,9 @@
 #define TLK_PREEMPTED		(0x32000002 | (1 << 31))
 #define TLK_ENTRY_DONE		(0x32000003 | (1 << 31))
 #define TLK_VA_TRANSLATE	(0x32000004 | (1 << 31))
+#define TLK_SUSPEND_DONE	(0x32000005 | (1 << 31))
+#define TLK_RESUME_DONE		(0x32000006 | (1 << 31))
+#define TLK_SYSTEM_OFF_DONE	(0x32000007 | (1 << 31))
 
 /*
  * Trusted Application specific function IDs

services/spd/tlkd/tlkd_main.c

@@ -54,9 +54,9 @@
 extern const spd_pm_ops_t tlkd_pm_ops;
 
 /*******************************************************************************
- * Array to keep track of per-cpu Secure Payload state
+ * Per-cpu Secure Payload state
  ******************************************************************************/
-static tlk_context_t tlk_ctx;
+tlk_context_t tlk_ctx;
 
 /* TLK UID: RFC-4122 compliant UUID (version-5, sha-1) */
 DEFINE_SVC_UUID(tlk_uuid,
@@ -386,6 +386,31 @@ uint64_t tlkd_smc_handler(uint32_t smc_fid,
 		 */
 		tlkd_synchronous_sp_exit(&tlk_ctx, x1);
 
+	/*
+	 * These function IDs are used only by TLK to indicate it has
+	 * finished:
+	 * 1. suspending itself after an earlier psci cpu_suspend
+	 *    request.
+	 * 2. resuming itself after an earlier psci cpu_suspend
+	 *    request.
+	 * 3. powering down after an earlier psci system_off/system_reset
+	 *    request.
+	 */
+	case TLK_SUSPEND_DONE:
+	case TLK_RESUME_DONE:
+	case TLK_SYSTEM_OFF_DONE:
+
+		if (ns)
+			SMC_RET1(handle, SMC_UNK);
+
+		/*
+		 * TLK reports completion. TLKD must have initiated the
+		 * original request through a synchronous entry into the SP.
+		 * Jump back to the original C runtime context, and pass x1 as
+		 * return value to the caller
+		 */
+		tlkd_synchronous_sp_exit(&tlk_ctx, x1);
+
 	/*
 	 * Return the number of service function IDs implemented to
 	 * provide service to non-secure

services/spd/tlkd/tlkd_pm.c

@@ -28,7 +28,17 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <arch_helpers.h>
+#include <assert.h>
+#include <bl_common.h>
+#include <context_mgmt.h>
+#include <debug.h>
 #include <psci.h>
+#include <tlk.h>
+
+#include "tlkd_private.h"
+
+extern tlk_context_t tlk_ctx;
 
 #define MPIDR_CPU0	0x80000000
 
@@ -45,10 +55,102 @@ static int32_t cpu_migrate_info(uint64_t *resident_cpu)
 	return PSCI_TOS_NOT_UP_MIG_CAP;
 }
 
+/*******************************************************************************
+ * This cpu is being suspended. Inform TLK of the SYSTEM_SUSPEND event, so
+ * that it can pass this information to its Trusted Apps.
+ ******************************************************************************/
+static void cpu_suspend_handler(uint64_t suspend_level)
+{
+	gp_regs_t *gp_regs;
+	int cpu = read_mpidr() & MPIDR_CPU_MASK;
+	int32_t rc = 0;
+
+	/*
+	 * TLK runs only on CPU0 and suspends its Trusted Apps during
+	 * SYSTEM_SUSPEND. It has no role to play during CPU_SUSPEND.
+	 */
+	if ((cpu != 0) || (suspend_level != PLAT_MAX_PWR_LVL))
+		return;
+
+	/* pass system suspend event to TLK */
+	gp_regs = get_gpregs_ctx(&tlk_ctx.cpu_ctx);
+	write_ctx_reg(gp_regs, CTX_GPREG_X0, TLK_SYSTEM_SUSPEND);
+
+	/* Program the entry point and enter TLK */
+	rc = tlkd_synchronous_sp_entry(&tlk_ctx);
+
+	/*
+	 * Read the response from TLK. A non-zero return means that
+	 * something went wrong while communicating with it.
+	 */
+	if (rc != 0)
+		panic();
+}
+
+/*******************************************************************************
+ * This cpu is being resumed. Inform TLK of the SYSTEM_SUSPEND exit, so
+ * that it can pass this information to its Trusted Apps.
+ ******************************************************************************/
+static void cpu_resume_handler(uint64_t suspend_level)
+{
+	gp_regs_t *gp_regs;
+	int cpu = read_mpidr() & MPIDR_CPU_MASK;
+	int32_t rc = 0;
+
+	/*
+	 * TLK runs only on CPU0 and resumes its Trusted Apps during
+	 * SYSTEM_SUSPEND exit. It has no role to play during CPU_SUSPEND
+	 * exit.
+	 */
+	if ((cpu != 0) || (suspend_level != PLAT_MAX_PWR_LVL))
+		return;
+
+	/* pass system resume event to TLK */
+	gp_regs = get_gpregs_ctx(&tlk_ctx.cpu_ctx);
+	write_ctx_reg(gp_regs, CTX_GPREG_X0, TLK_SYSTEM_RESUME);
+
+	/* Program the entry point and enter TLK */
+	rc = tlkd_synchronous_sp_entry(&tlk_ctx);
+
+	/*
+	 * Read the response from TLK. A non-zero return means that
+	 * something went wrong while communicating with it.
+	 */
+	if (rc != 0)
+		panic();
+}
+
+/*******************************************************************************
+ * System is about to be reset. Inform the SP to allow any book-keeping
+ ******************************************************************************/
+static void system_off_handler(void)
+{
+	int cpu = read_mpidr() & MPIDR_CPU_MASK;
+	gp_regs_t *gp_regs;
+
+	/* TLK runs only on CPU0 */
+	if (cpu != 0)
+		return;
+
+	/* pass system off/reset events to TLK */
+	gp_regs = get_gpregs_ctx(&tlk_ctx.cpu_ctx);
+	write_ctx_reg(gp_regs, CTX_GPREG_X0, TLK_SYSTEM_OFF);
+
+	/*
+	 * Enter the SP. We do not care about the return value because we
+	 * must continue with the shutdown anyway.
+	 */
+	(void)tlkd_synchronous_sp_entry(&tlk_ctx);
+}
+
 /*******************************************************************************
  * Structure populated by the Dispatcher to be given a chance to perform any
  * bookkeeping before PSCI executes a power mgmt.  operation.
  ******************************************************************************/
 const spd_pm_ops_t tlkd_pm_ops = {
 	.svc_migrate_info = cpu_migrate_info,
+	.svc_suspend = cpu_suspend_handler,
+	.svc_suspend_finish = cpu_resume_handler,
+	.svc_system_off = system_off_handler,
+	.svc_system_reset = system_off_handler
 };