soc: bcm: brcmstb: Add support for S2/S3/S5 suspend states (ARM)

This commit adds support for the Broadcom STB S2/S3/S5 suspend states on
ARM based SoCs.

This requires quite a lot of code in order to deal with the different HW
blocks that need to be quiesced during suspend:

- DDR PHY SHIM
- DDR memory controller and sequencer
- control processor

The final steps of the suspend execute in an on-chip SRAM and there is a
little bit of assembly code in order to shut down the DDR PHY PLL and
then go into a wfi loop until a wake-up even occurs. Conversely the
resume part involves waiting for the DDR PHY PLL to come back up and
resume executions where we left.

For S3, because of our memory hashing (actual hashing code not included
for simplicity, and is bypassed) we need to relocate the writable
variables (stack) into SRAM shortly before suspending in order to leave
the DRAM untouched and create a reliable hash of its contents.

This code has been contributed by Brian Norris initially and has been
incrementally fixed and updated to support new chips by a lot of people.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Markus Mayer <mmayer@broadcom.com>
Signed-off-by: Justin Chen <justinpopo6@gmail.com>
Signed-off-by: Gareth Powell <gpowell@broadcom.com>
Signed-off-by: Doug Berger <opendmb@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

drivers/soc/bcm/Kconfig

@@ -20,4 +20,6 @@ config SOC_BRCMSTB
 
 	  If unsure, say N.
 
+source "drivers/soc/bcm/brcmstb/Kconfig"
+
 endmenu

drivers/soc/bcm/brcmstb/Kconfig

@@ -0,0 +1,9 @@
+if SOC_BRCMSTB
+
+config BRCMSTB_PM
+	bool "Support suspend/resume for STB platforms"
+	default y
+	depends on PM
+	depends on ARM
+
+endif # SOC_BRCMSTB

drivers/soc/bcm/brcmstb/Makefile

@@ -1 +1,2 @@
 obj-y				+= common.o biuctrl.o
+obj-y				+= pm/

drivers/soc/bcm/brcmstb/pm/Makefile

@@ -0,0 +1,2 @@
+obj-$(CONFIG_ARM)		+= s2-arm.o pm-arm.o
+AFLAGS_s2-arm.o			:= -march=armv7-a

drivers/soc/bcm/brcmstb/pm/aon_defs.h

@@ -0,0 +1,113 @@
+/*
+ * Always ON (AON) register interface between bootloader and Linux
+ *
+ * Copyright © 2014-2017 Broadcom
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __BRCMSTB_AON_DEFS_H__
+#define __BRCMSTB_AON_DEFS_H__
+
+#include <linux/compiler.h>
+
+/* Magic number in upper 16-bits */
+#define BRCMSTB_S3_MAGIC_MASK                   0xffff0000
+#define BRCMSTB_S3_MAGIC_SHORT                  0x5AFE0000
+
+enum {
+	/* Restore random key for AES memory verification (off = fixed key) */
+	S3_FLAG_LOAD_RANDKEY		= (1 << 0),
+
+	/* Scratch buffer page table is present */
+	S3_FLAG_SCRATCH_BUFFER_TABLE	= (1 << 1),
+
+	/* Skip all memory verification */
+	S3_FLAG_NO_MEM_VERIFY		= (1 << 2),
+
+	/*
+	 * Modification of this bit reserved for bootloader only.
+	 * 1=PSCI started Linux, 0=Direct jump to Linux.
+	 */
+	S3_FLAG_PSCI_BOOT		= (1 << 3),
+
+	/*
+	 * Modification of this bit reserved for bootloader only.
+	 * 1=64 bit boot, 0=32 bit boot.
+	 */
+	S3_FLAG_BOOTED64		= (1 << 4),
+};
+
+#define BRCMSTB_HASH_LEN			(128 / 8) /* 128-bit hash */
+
+#define AON_REG_MAGIC_FLAGS			0x00
+#define AON_REG_CONTROL_LOW			0x04
+#define AON_REG_CONTROL_HIGH			0x08
+#define AON_REG_S3_HASH				0x0c /* hash of S3 params */
+#define AON_REG_CONTROL_HASH_LEN		0x1c
+#define AON_REG_PANIC				0x20
+
+#define BRCMSTB_S3_MAGIC		0x5AFEB007
+#define BRCMSTB_PANIC_MAGIC		0x512E115E
+#define BOOTLOADER_SCRATCH_SIZE		64
+#define BRCMSTB_DTU_STATE_MAP_ENTRIES	(8*1024)
+#define BRCMSTB_DTU_CONFIG_ENTRIES	(512)
+#define BRCMSTB_DTU_COUNT		(2)
+
+#define IMAGE_DESCRIPTORS_BUFSIZE	(2 * 1024)
+#define S3_BOOTLOADER_RESERVED		(S3_FLAG_PSCI_BOOT | S3_FLAG_BOOTED64)
+
+struct brcmstb_bootloader_dtu_table {
+	uint32_t	dtu_state_map[BRCMSTB_DTU_STATE_MAP_ENTRIES];
+	uint32_t	dtu_config[BRCMSTB_DTU_CONFIG_ENTRIES];
+};
+
+/*
+ * Bootloader utilizes a custom parameter block left in DRAM for handling S3
+ * warm resume
+ */
+struct brcmstb_s3_params {
+	/* scratch memory for bootloader */
+	uint8_t scratch[BOOTLOADER_SCRATCH_SIZE];
+
+	uint32_t magic; /* BRCMSTB_S3_MAGIC */
+	uint64_t reentry; /* PA */
+
+	/* descriptors */
+	uint32_t hash[BRCMSTB_HASH_LEN / 4];
+
+	/*
+	 * If 0, then ignore this parameter (there is only one set of
+	 *   descriptors)
+	 *
+	 * If non-0, then a second set of descriptors is stored at:
+	 *
+	 *   descriptors + desc_offset_2
+	 *
+	 * The MAC result of both descriptors is XOR'd and stored in @hash
+	 */
+	uint32_t desc_offset_2;
+
+	/*
+	 * (Physical) address of a brcmstb_bootloader_scratch_table, for
+	 * providing a large DRAM buffer to the bootloader
+	 */
+	uint64_t buffer_table;
+
+	uint32_t spare[70];
+
+	uint8_t descriptors[IMAGE_DESCRIPTORS_BUFSIZE];
+	/*
+	 * Must be last member of struct. See brcmstb_pm_s3_finish() for reason.
+	 */
+	struct brcmstb_bootloader_dtu_table dtu[BRCMSTB_DTU_COUNT];
+} __packed;
+
+#endif /* __BRCMSTB_AON_DEFS_H__ */