arm64: CPU support

This patch adds AArch64 CPU specific functionality. It assumes that the
implementation is generic to AArch64 and does not require specific
identification. Different CPU implementations may require the setting of
various ACTLR_EL1 bits but such information is not currently available
and it should ideally be pushed to firmware.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>

1 files changed, 186 insertions, 0 deletions

diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
new file mode 100644
index 00000000000..720aa0b3bee
--- /dev/null
+++ b/arch/arm64/mm/proc.S
@@ -0,0 +1,186 @@
+/*
+ * Based on arch/arm/mm/proc.S
+ *
+ * Copyright (C) 2001 Deep Blue Solutions Ltd.
+ * Copyright (C) 2012 ARM Ltd.
+ * Author: Catalin Marinas <catalin.marinas@arm.com>
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/init.h>
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+#include <asm/asm-offsets.h>
+#include <asm/hwcap.h>
+#include <asm/pgtable-hwdef.h>
+#include <asm/pgtable.h>
+
+#include "proc-macros.S"
+
+#ifndef CONFIG_SMP
+/* PTWs cacheable, inner/outer WBWA not shareable */
+#define TCR_FLAGS	TCR_IRGN_WBWA | TCR_ORGN_WBWA
+#else
+/* PTWs cacheable, inner/outer WBWA shareable */
+#define TCR_FLAGS	TCR_IRGN_WBWA | TCR_ORGN_WBWA | TCR_SHARED
+#endif
+
+#define MAIR(attr, mt)	((attr) << ((mt) * 8))
+
+/*
+ *	cpu_cache_off()
+ *
+ *	Turn the CPU D-cache off.
+ */
+ENTRY(cpu_cache_off)
+	mrs	x0, sctlr_el1
+	bic	x0, x0, #1 << 2			// clear SCTLR.C
+	msr	sctlr_el1, x0
+	isb
+	ret
+ENDPROC(cpu_cache_off)
+
+/*
+ *	cpu_reset(loc)
+ *
+ *	Perform a soft reset of the system.  Put the CPU into the same state
+ *	as it would be if it had been reset, and branch to what would be the
+ *	reset vector. It must be executed with the flat identity mapping.
+ *
+ *	- loc   - location to jump to for soft reset
+ */
+	.align	5
+ENTRY(cpu_reset)
+	mrs	x1, sctlr_el1
+	bic	x1, x1, #1
+	msr	sctlr_el1, x1			// disable the MMU
+	isb
+	ret	x0
+ENDPROC(cpu_reset)
+
+/*
+ *	cpu_do_idle()
+ *
+ *	Idle the processor (wait for interrupt).
+ */
+ENTRY(cpu_do_idle)
+	dsb	sy				// WFI may enter a low-power mode
+	wfi
+	ret
+ENDPROC(cpu_do_idle)
+
+/*
+ *	cpu_switch_mm(pgd_phys, tsk)
+ *
+ *	Set the translation table base pointer to be pgd_phys.
+ *
+ *	- pgd_phys - physical address of new TTB
+ */
+ENTRY(cpu_do_switch_mm)
+	mmid	w1, x1				// get mm->context.id
+	bfi	x0, x1, #48, #16		// set the ASID
+	msr	ttbr0_el1, x0			// set TTBR0
+	isb
+	ret
+ENDPROC(cpu_do_switch_mm)
+
+cpu_name:
+	.ascii	"AArch64 Processor"
+	.align
+
+	.section ".text.init", #alloc, #execinstr
+
+/*
+ *	__cpu_setup
+ *
+ *	Initialise the processor for turning the MMU on.  Return in x0 the
+ *	value of the SCTLR_EL1 register.
+ */
+ENTRY(__cpu_setup)
+#ifdef CONFIG_SMP
+	/* TODO: only do this for certain CPUs */
+	/*
+	 * Enable SMP/nAMP mode.
+	 */
+	mrs	x0, actlr_el1
+	tbnz	x0, #6, 1f			// already enabled?
+	orr	x0, x0, #1 << 6
+	msr	actlr_el1, x0
+1:
+#endif
+	/*
+	 * Preserve the link register across the function call.
+	 */
+	mov	x28, lr
+	bl	__flush_dcache_all
+	mov	lr, x28
+	ic	iallu				// I+BTB cache invalidate
+	dsb	sy
+
+	mov	x0, #3 << 20
+	msr	cpacr_el1, x0			// Enable FP/ASIMD
+	mov	x0, #1
+	msr	oslar_el1, x0			// Set the debug OS lock
+	tlbi	vmalle1is			// invalidate I + D TLBs
+	/*
+	 * Memory region attributes for LPAE:
+	 *
+	 *   n = AttrIndx[2:0]
+	 *			n	MAIR
+	 *   DEVICE_nGnRnE	000	00000000
+	 *   DEVICE_nGnRE	001	00000100
+	 *   DEVICE_GRE		010	00001100
+	 *   NORMAL_NC		011	01000100
+	 *   NORMAL		100	11111111
+	 */
+	ldr	x5, =MAIR(0x00, MT_DEVICE_nGnRnE) | \
+		     MAIR(0x04, MT_DEVICE_nGnRE) | \
+		     MAIR(0x0c, MT_DEVICE_GRE) | \
+		     MAIR(0x44, MT_NORMAL_NC) | \
+		     MAIR(0xff, MT_NORMAL)
+	msr	mair_el1, x5
+	/*
+	 * Prepare SCTLR
+	 */
+	adr	x5, crval
+	ldp	w5, w6, [x5]
+	mrs	x0, sctlr_el1
+	bic	x0, x0, x5			// clear bits
+	orr	x0, x0, x6			// set bits
+	/*
+	 * Set/prepare TCR and TTBR. We use 512GB (39-bit) address range for
+	 * both user and kernel.
+	 */
+	ldr	x10, =TCR_TxSZ(VA_BITS) | TCR_FLAGS | TCR_IPS_40BIT | \
+		      TCR_ASID16 | (1 << 31)
+#ifdef CONFIG_ARM64_64K_PAGES
+	orr	x10, x10, TCR_TG0_64K
+	orr	x10, x10, TCR_TG1_64K
+#endif
+	msr	tcr_el1, x10
+	ret					// return to head.S
+ENDPROC(__cpu_setup)
+
+	/*
+	 *                 n n            T
+	 *       U E      WT T UD     US IHBS
+	 *       CE0      XWHW CZ     ME TEEA S
+	 * .... .IEE .... NEAI TE.I ..AD DEN0 ACAM
+	 * 0011 0... 1101 ..0. ..0. 10.. .... .... < hardware reserved
+	 * .... .100 .... 01.1 11.1 ..01 0001 1101 < software settings
+	 */
+	.type	crval, #object
+crval:
+	.word	0x030802e2			// clear
+	.word	0x0405d11d			// set