rpi: move plat_helpers.S to common

The plat_helpers.S file was almost identical between its RPi3 and RPi4
versions. Unify the two files, moving it into the common/ directory.

This adds a plat_rpi_get_model() function, which can be used to trigger
RPi4 specific action, detected at runtime. We use that to do the RPi4
specific L2 cache initialisation.

Change-Id: I2295704fd6dde7c76fe83b6d98c7bf998d4bf074
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/plat/rpi/common/aarch64/plat_helpers.S b/plat/rpi/common/aarch64/plat_helpers.S
new file mode 100644
index 0000000..93c8f7f
--- /dev/null
+++ b/plat/rpi/common/aarch64/plat_helpers.S
@@ -0,0 +1,214 @@
+/*
+ * Copyright (c) 2015-2020, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch.h>
+#include <asm_macros.S>
+#include <assert_macros.S>
+#include <platform_def.h>
+#include <cortex_a72.h>
+
+	.globl	plat_crash_console_flush
+	.globl	plat_crash_console_init
+	.globl	plat_crash_console_putc
+	.globl	platform_mem_init
+	.globl	plat_get_my_entrypoint
+	.globl	plat_is_my_cpu_primary
+	.globl	plat_my_core_pos
+	.globl	plat_reset_handler
+	.globl	plat_rpi3_calc_core_pos
+	.globl	plat_secondary_cold_boot_setup
+	.globl	plat_rpi_get_model
+
+	/* -----------------------------------------------------
+	 *  unsigned int plat_my_core_pos(void)
+	 *
+	 *  This function uses the plat_rpi3_calc_core_pos()
+	 *  definition to get the index of the calling CPU.
+	 * -----------------------------------------------------
+	 */
+func plat_my_core_pos
+	mrs	x0, mpidr_el1
+	b	plat_rpi3_calc_core_pos
+endfunc plat_my_core_pos
+
+	/* -----------------------------------------------------
+	 *  unsigned int plat_rpi3_calc_core_pos(u_register_t mpidr);
+	 *
+	 *  CorePos = (ClusterId * 4) + CoreId
+	 * -----------------------------------------------------
+	 */
+func plat_rpi3_calc_core_pos
+	and	x1, x0, #MPIDR_CPU_MASK
+	and	x0, x0, #MPIDR_CLUSTER_MASK
+	add	x0, x1, x0, LSR #6
+	ret
+endfunc plat_rpi3_calc_core_pos
+
+	/* -----------------------------------------------------
+	 * unsigned int plat_is_my_cpu_primary (void);
+	 *
+	 * Find out whether the current cpu is the primary
+	 * cpu.
+	 * -----------------------------------------------------
+	 */
+func plat_is_my_cpu_primary
+	mrs	x0, mpidr_el1
+	and	x0, x0, #(MPIDR_CLUSTER_MASK | MPIDR_CPU_MASK)
+	cmp	x0, #RPI_PRIMARY_CPU
+	cset	w0, eq
+	ret
+endfunc plat_is_my_cpu_primary
+
+	/* -----------------------------------------------------
+	 * void plat_secondary_cold_boot_setup (void);
+	 *
+	 * This function performs any platform specific actions
+	 * needed for a secondary cpu after a cold reset e.g
+	 * mark the cpu's presence, mechanism to place it in a
+	 * holding pen etc.
+	 * -----------------------------------------------------
+	 */
+func plat_secondary_cold_boot_setup
+	/* Calculate address of our hold entry */
+	bl	plat_my_core_pos
+	lsl	x0, x0, #3
+	mov_imm	x2, PLAT_RPI3_TM_HOLD_BASE
+	add	x0, x0, x2
+
+	/*
+	 * This code runs way before requesting the warmboot of this core,
+	 * so it is possible to clear the mailbox before getting a request
+	 * to boot.
+	 */
+	mov	x1, PLAT_RPI3_TM_HOLD_STATE_WAIT
+	str	x1,[x0]
+
+	/* Wait until we have a go */
+poll_mailbox:
+	wfe
+	ldr	x1, [x0]
+	cmp	x1, PLAT_RPI3_TM_HOLD_STATE_GO
+	bne	poll_mailbox
+
+	/* Jump to the provided entrypoint */
+	mov_imm	x0, PLAT_RPI3_TM_ENTRYPOINT
+	ldr	x1, [x0]
+	br	x1
+endfunc plat_secondary_cold_boot_setup
+
+	/* ---------------------------------------------------------------------
+	 * uintptr_t plat_get_my_entrypoint (void);
+	 *
+	 * Main job of this routine is to distinguish between a cold and a warm
+	 * boot.
+	 *
+	 * This functions returns:
+	 *  - 0 for a cold boot.
+	 *  - Any other value for a warm boot.
+	 * ---------------------------------------------------------------------
+	 */
+func plat_get_my_entrypoint
+	/* TODO: support warm boot */
+	mov	x0, #0
+	ret
+endfunc plat_get_my_entrypoint
+
+	/* ---------------------------------------------
+	 * void platform_mem_init (void);
+	 *
+	 * No need to carry out any memory initialization.
+	 * ---------------------------------------------
+	 */
+func platform_mem_init
+	ret
+endfunc platform_mem_init
+
+	/* ---------------------------------------------
+	 * int plat_crash_console_init(void)
+	 * Function to initialize the crash console
+	 * without a C Runtime to print crash report.
+	 * Clobber list : x0 - x3
+	 * ---------------------------------------------
+	 */
+func plat_crash_console_init
+	mov_imm	x0, PLAT_RPI_MINI_UART_BASE
+	mov	x1, xzr
+	mov	x2, xzr
+	b	console_16550_core_init
+endfunc plat_crash_console_init
+
+	/* ---------------------------------------------
+	 * int plat_crash_console_putc(int c)
+	 * Function to print a character on the crash
+	 * console without a C Runtime.
+	 * Clobber list : x1, x2
+	 * ---------------------------------------------
+	 */
+func plat_crash_console_putc
+	mov_imm	x1, PLAT_RPI_MINI_UART_BASE
+	b	console_16550_core_putc
+endfunc plat_crash_console_putc
+
+	/* ---------------------------------------------
+	 * int plat_crash_console_flush()
+	 * Function to force a write of all buffered
+	 * data that hasn't been output.
+	 * Out : return -1 on error else return 0.
+	 * Clobber list : x0, x1
+	 * ---------------------------------------------
+	 */
+func plat_crash_console_flush
+	mov_imm	x0, PLAT_RPI_MINI_UART_BASE
+	b	console_16550_core_flush
+endfunc plat_crash_console_flush
+
+	/* ---------------------------------------------
+	 * int plat_rpi_get_model()
+	 * Macro to determine whether we are running on
+	 * a Raspberry Pi 3 or 4. Just checks the MIDR for
+	 * being either a Cortex-A72 or a Cortex-A53.
+	 * Out : return 4 if RPi4, 3 otherwise.
+	 * Clobber list : x0
+	 * ---------------------------------------------
+	 */
+	.macro _plat_rpi_get_model
+	mrs	x0, midr_el1
+	and	x0, x0, #0xf0	/* Isolate low byte of part number */
+	cmp	w0, #0x80	/* Cortex-A72 (RPi4) is 0xd08, A53 is 0xd03 */
+	mov	w0, #3
+	csinc	w0, w0, w0, ne
+	.endm
+
+	func plat_rpi_get_model
+	_plat_rpi_get_model
+	ret
+	endfunc plat_rpi_get_model
+
+	/* ---------------------------------------------
+	 * void plat_reset_handler(void);
+	 * ---------------------------------------------
+	 */
+func plat_reset_handler
+	/* L2 cache setup only needed on RPi4 */
+	_plat_rpi_get_model
+	cmp	w0, #4
+	b.ne	1f
+
+	/* ------------------------------------------------
+	 * Set L2 read/write cache latency:
+	 * - L2 Data RAM latency: 3 cycles (0b010)
+	 * - L2 Data RAM setup: 1 cycle (bit 5)
+	 * ------------------------------------------------
+	 */
+	mrs	x0, CORTEX_A72_L2CTLR_EL1
+	mov	x1, #0x22
+	orr	x0, x0, x1
+	msr	CORTEX_A72_L2CTLR_EL1, x0
+	isb
+
+1:
+	ret
+endfunc plat_reset_handler
diff --git a/plat/rpi/common/include/rpi_shared.h b/plat/rpi/common/include/rpi_shared.h
index 6863438..ddf239e 100644
--- a/plat/rpi/common/include/rpi_shared.h
+++ b/plat/rpi/common/include/rpi_shared.h
@@ -36,4 +36,6 @@
 /* VideoCore firmware commands */
 int rpi3_vc_hardware_get_board_revision(uint32_t *revision);
 
+int plat_rpi_get_model(void);
+
 #endif /* RPI3_PRIVATE_H */