MIPS: BMIPS: Add SMP support code for BMIPS43xx/BMIPS5000

Initial commit of BMIPS SMP support code.  Smoke-tested on a variety of
BMIPS4350, BMIPS4380, and BMIPS5000 platforms.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2977/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 255 insertions, 0 deletions

diff --git a/arch/mips/kernel/bmips_vec.S b/arch/mips/kernel/bmips_vec.S
new file mode 100644
index 000000000000..e908e81330b1
--- /dev/null
+++ b/arch/mips/kernel/bmips_vec.S
@@ -0,0 +1,255 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2011 by Kevin Cernekee (cernekee@gmail.com)
+ *
+ * Reset/NMI/re-entry vectors for BMIPS processors
+ */
+
+#include <linux/init.h>
+
+#include <asm/asm.h>
+#include <asm/asmmacro.h>
+#include <asm/cacheops.h>
+#include <asm/regdef.h>
+#include <asm/mipsregs.h>
+#include <asm/stackframe.h>
+#include <asm/addrspace.h>
+#include <asm/hazards.h>
+#include <asm/bmips.h>
+
+	.macro	BARRIER
+	.set	mips32
+	_ssnop
+	_ssnop
+	_ssnop
+	.set	mips0
+	.endm
+
+	__CPUINIT
+
+/***********************************************************************
+ * Alternate CPU1 startup vector for BMIPS4350
+ *
+ * On some systems the bootloader has already started CPU1 and configured
+ * it to resume execution at 0x8000_0200 (!BEV IV vector) when it is
+ * triggered by the SW1 interrupt.  If that is the case we try to move
+ * it to a more convenient place: BMIPS_WARM_RESTART_VEC @ 0x8000_0380.
+ ***********************************************************************/
+
+LEAF(bmips_smp_movevec)
+	la	k0, 1f
+	li	k1, CKSEG1
+	or	k0, k1
+	jr	k0
+
+1:
+	/* clear IV, pending IPIs */
+	mtc0	zero, CP0_CAUSE
+
+	/* re-enable IRQs to wait for SW1 */
+	li	k0, ST0_IE | ST0_BEV | STATUSF_IP1
+	mtc0	k0, CP0_STATUS
+
+	/* set up CPU1 CBR; move BASE to 0xa000_0000 */
+	li	k0, 0xff400000
+	mtc0	k0, $22, 6
+	li	k1, CKSEG1 | BMIPS_RELO_VECTOR_CONTROL_1
+	or	k0, k1
+	li	k1, 0xa0080000
+	sw	k1, 0(k0)
+
+	/* wait here for SW1 interrupt from bmips_boot_secondary() */
+	wait
+
+	la	k0, bmips_reset_nmi_vec
+	li	k1, CKSEG1
+	or	k0, k1
+	jr	k0
+END(bmips_smp_movevec)
+
+/***********************************************************************
+ * Reset/NMI vector
+ * For BMIPS processors that can relocate their exception vectors, this
+ * entire function gets copied to 0x8000_0000.
+ ***********************************************************************/
+
+NESTED(bmips_reset_nmi_vec, PT_SIZE, sp)
+	.set	push
+	.set	noat
+	.align	4
+
+#ifdef CONFIG_SMP
+	/* if the NMI bit is clear, assume this is a CPU1 reset instead */
+	li	k1, (1 << 19)
+	mfc0	k0, CP0_STATUS
+	and	k0, k1
+	beqz	k0, bmips_smp_entry
+
+#if defined(CONFIG_CPU_BMIPS5000)
+	/* if we're not on core 0, this must be the SMP boot signal */
+	li	k1, (3 << 25)
+	mfc0	k0, $22
+	and	k0, k1
+	bnez	k0, bmips_smp_entry
+#endif
+#endif /* CONFIG_SMP */
+
+	/* nope, it's just a regular NMI */
+	SAVE_ALL
+	move	a0, sp
+
+	/* clear EXL, ERL, BEV so that TLB refills still work */
+	mfc0	k0, CP0_STATUS
+	li	k1, ST0_ERL | ST0_EXL | ST0_BEV | ST0_IE
+	or	k0, k1
+	xor	k0, k1
+	mtc0	k0, CP0_STATUS
+	BARRIER
+
+	/* jump to the NMI handler function */
+	la	k0, nmi_handler
+	jr	k0
+
+	RESTORE_ALL
+	.set	mips3
+	eret
+
+/***********************************************************************
+ * CPU1 reset vector (used for the initial boot only)
+ * This is still part of bmips_reset_nmi_vec().
+ ***********************************************************************/
+
+#ifdef CONFIG_SMP
+
+bmips_smp_entry:
+
+	/* set up CP0 STATUS; enable FPU */
+	li	k0, 0x30000000
+	mtc0	k0, CP0_STATUS
+	BARRIER
+
+	/* set local CP0 CONFIG to make kseg0 cacheable, write-back */
+	mfc0	k0, CP0_CONFIG
+	ori	k0, 0x07
+	xori	k0, 0x04
+	mtc0	k0, CP0_CONFIG
+
+#if defined(CONFIG_CPU_BMIPS4350) || defined(CONFIG_CPU_BMIPS4380)
+	/* initialize CPU1's local I-cache */
+	li	k0, 0x80000000
+	li	k1, 0x80010000
+	mtc0	zero, $28
+	mtc0	zero, $28, 1
+	BARRIER
+
+1:	cache	Index_Store_Tag_I, 0(k0)
+	addiu	k0, 16
+	bne	k0, k1, 1b
+#elif defined(CONFIG_CPU_BMIPS5000)
+	/* set exception vector base */
+	la	k0, ebase
+	lw	k0, 0(k0)
+	mtc0	k0, $15, 1
+	BARRIER
+#endif
+
+	/* jump back to kseg0 in case we need to remap the kseg1 area */
+	la	k0, 1f
+	jr	k0
+1:
+	la	k0, bmips_enable_xks01
+	jalr	k0
+
+	/* use temporary stack to set up upper memory TLB */
+	li	sp, BMIPS_WARM_RESTART_VEC
+	la	k0, plat_wired_tlb_setup
+	jalr	k0
+
+	/* switch to permanent stack and continue booting */
+
+	.global	bmips_secondary_reentry
+bmips_secondary_reentry:
+	la	k0, bmips_smp_boot_sp
+	lw	sp, 0(k0)
+	la	k0, bmips_smp_boot_gp
+	lw	gp, 0(k0)
+	la	k0, start_secondary
+	jr	k0
+
+#endif /* CONFIG_SMP */
+
+	.align	4
+	.global	bmips_reset_nmi_vec_end
+bmips_reset_nmi_vec_end:
+
+END(bmips_reset_nmi_vec)
+
+	.set	pop
+	.previous
+
+/***********************************************************************
+ * CPU1 warm restart vector (used for second and subsequent boots).
+ * Also used for S2 standby recovery (PM).
+ * This entire function gets copied to (BMIPS_WARM_RESTART_VEC)
+ ***********************************************************************/
+
+LEAF(bmips_smp_int_vec)
+
+	.align	4
+	mfc0	k0, CP0_STATUS
+	ori	k0, 0x01
+	xori	k0, 0x01
+	mtc0	k0, CP0_STATUS
+	eret
+
+	.align	4
+	.global	bmips_smp_int_vec_end
+bmips_smp_int_vec_end:
+
+END(bmips_smp_int_vec)
+
+/***********************************************************************
+ * XKS01 support
+ * Certain CPUs support extending kseg0 to 1024MB.
+ ***********************************************************************/
+
+	__CPUINIT
+
+LEAF(bmips_enable_xks01)
+
+#if defined(CONFIG_XKS01)
+
+#if defined(CONFIG_CPU_BMIPS4380)
+	mfc0	t0, $22, 3
+	li	t1, 0x1ff0
+	li	t2, (1 << 12) | (1 << 9)
+	or	t0, t1
+	xor	t0, t1
+	or	t0, t2
+	mtc0	t0, $22, 3
+	BARRIER
+#elif defined(CONFIG_CPU_BMIPS5000)
+	mfc0	t0, $22, 5
+	li	t1, 0x01ff
+	li	t2, (1 << 8) | (1 << 5)
+	or	t0, t1
+	xor	t0, t1
+	or	t0, t2
+	mtc0	t0, $22, 5
+	BARRIER
+#else
+
+#error Missing XKS01 setup
+
+#endif
+
+#endif /* defined(CONFIG_XKS01) */
+
+	jr	ra
+
+END(bmips_enable_xks01)
+
+	.previous