synquacer: Add MHU driver

Add Message Handling Unit (MHU) driver used to communicate among
Application Processors (AP) and System Control Processor (SCP).
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>

plat/socionext/synquacer/drivers/mhu/sq_mhu.c

+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch_helpers.h>
+#include <assert.h>
+#include <bakery_lock.h>
+#include <mmio.h>
+#include <platform_def.h>
+#include <sq_common.h>
+#include "sq_mhu.h"
+
+/* SCP MHU secure channel registers */
+#define SCP_INTR_S_STAT		0x200
+#define SCP_INTR_S_SET		0x208
+#define SCP_INTR_S_CLEAR	0x210
+
+/* CPU MHU secure channel registers */
+#define CPU_INTR_S_STAT		0x300
+#define CPU_INTR_S_SET		0x308
+#define CPU_INTR_S_CLEAR	0x310
+
+DEFINE_BAKERY_LOCK(sq_lock);
+
+/*
+ * Slot 31 is reserved because the MHU hardware uses this register bit to
+ * indicate a non-secure access attempt. The total number of available slots is
+ * therefore 31 [30:0].
+ */
+#define MHU_MAX_SLOT_ID		30
+
+void mhu_secure_message_start(unsigned int slot_id)
+{
+	assert(slot_id <= MHU_MAX_SLOT_ID);
+
+	bakery_lock_get(&sq_lock);
+
+	/* Make sure any previous command has finished */
+	while (mmio_read_32(PLAT_SQ_MHU_BASE + CPU_INTR_S_STAT) &
+							(1 << slot_id))
+		;
+}
+
+void mhu_secure_message_send(unsigned int slot_id)
+{
+	assert(slot_id <= MHU_MAX_SLOT_ID);
+	assert(!(mmio_read_32(PLAT_SQ_MHU_BASE + CPU_INTR_S_STAT) &
+							(1 << slot_id)));
+
+	/* Send command to SCP */
+	mmio_write_32(PLAT_SQ_MHU_BASE + CPU_INTR_S_SET, 1 << slot_id);
+}
+
+uint32_t mhu_secure_message_wait(void)
+{
+	uint32_t response;
+
+	/* Wait for response from SCP */
+	while (!(response = mmio_read_32(PLAT_SQ_MHU_BASE + SCP_INTR_S_STAT)))
+		;
+
+	return response;
+}
+
+void mhu_secure_message_end(unsigned int slot_id)
+{
+	assert(slot_id <= MHU_MAX_SLOT_ID);
+
+	/*
+	 * Clear any response we got by writing one in the relevant slot bit to
+	 * the CLEAR register
+	 */
+	mmio_write_32(PLAT_SQ_MHU_BASE + SCP_INTR_S_CLEAR, 1 << slot_id);
+
+	bakery_lock_release(&sq_lock);
+}
+
+void mhu_secure_init(void)
+{
+	bakery_lock_init(&sq_lock);
+
+	/*
+	 * The STAT register resets to zero. Ensure it is in the expected state,
+	 * as a stale or garbage value would make us think it's a message we've
+	 * already sent.
+	 */
+	assert(mmio_read_32(PLAT_SQ_MHU_BASE + CPU_INTR_S_STAT) == 0);
+}
+
+void plat_sq_pwrc_setup(void)
+{
+	mhu_secure_init();
+}

plat/socionext/synquacer/drivers/mhu/sq_mhu.h

+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef __SQ_MHU_H__
+#define __SQ_MHU_H__
+
+#include <stdint.h>
+
+void mhu_secure_message_start(unsigned int slot_id);
+void mhu_secure_message_send(unsigned int slot_id);
+uint32_t mhu_secure_message_wait(void);
+void mhu_secure_message_end(unsigned int slot_id);
+
+void mhu_secure_init(void);
+
+#endif	/* __SQ_MHU_H__ */

plat/socionext/synquacer/include/platform_def.h

@@ -54,6 +54,8 @@
 #define SQ_SYS_TIMCTL_BASE		0x2a810000
 #define PLAT_SQ_NSTIMER_FRAME_ID	0
 
+#define PLAT_SQ_MHU_BASE		0x45000000
+
 #define SQ_BOOT_CFG_ADDR			0x45410000
 #define PLAT_SQ_PRIMARY_CPU_SHIFT		8
 #define PLAT_SQ_PRIMARY_CPU_BIT_WIDTH		6

plat/socionext/synquacer/include/sq_common.h

@@ -10,6 +10,8 @@
 #include <sys/types.h>
 #include <xlat_tables_v2.h>
 
+void plat_sq_pwrc_setup(void);
+
 void plat_sq_interconnect_init(void);
 void plat_sq_interconnect_enter_coherency(void);
 void plat_sq_interconnect_exit_coherency(void);

plat/socionext/synquacer/sq_bl31_setup.c

@@ -125,6 +125,9 @@ void bl31_platform_setup(void)
 
 	/* Allow access to the System counter timer module */
 	sq_configure_sys_timer();
+
+	/* Initialize power controller before setting up topology */
+	plat_sq_pwrc_setup();
 }
 
 void bl31_plat_runtime_setup(void)