Add support for QEMU "max" CPU

Enable basic support for QEMU "max" CPU.
The "max" CPU does not attampt to emulate any specific CPU, but rather
just enables all the functions emulated by QEMU.

Change-Id: I69c212932ef61433509662d0fefbabb1e9e71cf2
Signed-off-by: Leif Lindholm <leif@nuviainc.com>

include/lib/cpus/aarch64/qemu_max.h

+/*
+ * Copyright (c) 2014-2021, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef QEMU_MAX_H
+#define QEMU_MAX_H
+
+#include <lib/utils_def.h>
+
+/*
+ *  QEMU MAX midr for revision 0
+ *  00   - Reserved for software use
+ *  0    - Variant
+ *  F    - Architectural features identified in ID_* registers
+ *  051  - 'Q', in a 12-bit field.
+ *  0    - Revision
+ */
+#define QEMU_MAX_MIDR		U(0x000F0510)
+
+#endif /* QEMU_MAX_H */

lib/cpus/aarch64/qemu_max.S

+/*
+ * Copyright (c) 2014-2021, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+#include <arch.h>
+#include <asm_macros.S>
+#include <cpu_macros.S>
+#include <qemu_max.h>
+
+func qemu_max_core_pwr_dwn
+	/* ---------------------------------------------
+	 * Disable the Data Cache.
+	 * ---------------------------------------------
+	 */
+	mrs	x1, sctlr_el3
+	bic	x1, x1, #SCTLR_C_BIT
+	msr	sctlr_el3, x1
+	isb
+
+	/* ---------------------------------------------
+	 * Flush L1 cache to L2.
+	 * ---------------------------------------------
+	 */
+	mov	x18, lr
+	mov	x0, #DCCISW
+	bl	dcsw_op_level1
+	mov	lr, x18
+	ret
+endfunc qemu_max_core_pwr_dwn
+
+func qemu_max_cluster_pwr_dwn
+	/* ---------------------------------------------
+	 * Disable the Data Cache.
+	 * ---------------------------------------------
+	 */
+	mrs	x1, sctlr_el3
+	bic	x1, x1, #SCTLR_C_BIT
+	msr	sctlr_el3, x1
+	isb
+
+	/* ---------------------------------------------
+	 * Flush all caches to PoC.
+	 * ---------------------------------------------
+	 */
+	mov	x0, #DCCISW
+	b	dcsw_op_all
+endfunc qemu_max_cluster_pwr_dwn
+
+#if REPORT_ERRATA
+/*
+ * Errata printing function for QEMU "max". Must follow AAPCS.
+ */
+func qemu_max_errata_report
+	ret
+endfunc qemu_max_errata_report
+#endif
+
+	/* ---------------------------------------------
+	 * This function provides cpu specific
+	 * register information for crash reporting.
+	 * It needs to return with x6 pointing to
+	 * a list of register names in ascii and
+	 * x8 - x15 having values of registers to be
+	 * reported.
+	 * ---------------------------------------------
+	 */
+.section .rodata.qemu_max_regs, "aS"
+qemu_max_regs:  /* The ascii list of register names to be reported */
+	.asciz	"" /* no registers to report */
+
+func qemu_max_cpu_reg_dump
+	adr	x6, qemu_max_regs
+	ret
+endfunc qemu_max_cpu_reg_dump
+
+
+/* cpu_ops for QEMU MAX */
+declare_cpu_ops qemu_max, QEMU_MAX_MIDR, CPU_NO_RESET_FUNC, \
+	qemu_max_core_pwr_dwn, \
+	qemu_max_cluster_pwr_dwn