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+/*
+ * linux/arch/arm/kernel/iwmmxt.S
+ *
+ * XScale iWMMXt (Concan) context switching and handling
+ *
+ * Initial code:
+ * Copyright (c) 2003, Intel Corporation
+ *
+ * Full lazy switching support, optimizations and more, by Nicolas Pitre
+* Copyright (c) 2003-2004, MontaVista Software, Inc.
+ *
+ * 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.
+ */
+
+#include <linux/linkage.h>
+#include <asm/ptrace.h>
+#include <asm/thread_info.h>
+#include <asm/constants.h>
+
+#define MMX_WR0 (0x00)
+#define MMX_WR1 (0x08)
+#define MMX_WR2 (0x10)
+#define MMX_WR3 (0x18)
+#define MMX_WR4 (0x20)
+#define MMX_WR5 (0x28)
+#define MMX_WR6 (0x30)
+#define MMX_WR7 (0x38)
+#define MMX_WR8 (0x40)
+#define MMX_WR9 (0x48)
+#define MMX_WR10 (0x50)
+#define MMX_WR11 (0x58)
+#define MMX_WR12 (0x60)
+#define MMX_WR13 (0x68)
+#define MMX_WR14 (0x70)
+#define MMX_WR15 (0x78)
+#define MMX_WCSSF (0x80)
+#define MMX_WCASF (0x84)
+#define MMX_WCGR0 (0x88)
+#define MMX_WCGR1 (0x8C)
+#define MMX_WCGR2 (0x90)
+#define MMX_WCGR3 (0x94)
+
+#define MMX_SIZE (0x98)
+
+ .text
+
+/*
+ * Lazy switching of Concan coprocessor context
+ *
+ * r10 = struct thread_info pointer
+ * r9 = ret_from_exception
+ * lr = undefined instr exit
+ *
+ * called from prefetch exception handler with interrupts disabled
+ */
+
+ENTRY(iwmmxt_task_enable)
+
+ mrc p15, 0, r2, c15, c1, 0
+ tst r2, #0x3 @ CP0 and CP1 accessible?
+ movne pc, lr @ if so no business here
+ orr r2, r2, #0x3 @ enable access to CP0 and CP1
+ mcr p15, 0, r2, c15, c1, 0
+
+ ldr r3, =concan_owner
+ add r0, r10, #TI_IWMMXT_STATE @ get task Concan save area
+ ldr r2, [sp, #60] @ current task pc value
+ ldr r1, [r3] @ get current Concan owner
+ str r0, [r3] @ this task now owns Concan regs
+ sub r2, r2, #4 @ adjust pc back
+ str r2, [sp, #60]
+
+ mrc p15, 0, r2, c2, c0, 0
+ mov r2, r2 @ cpwait
+
+ teq r1, #0 @ test for last ownership
+ mov lr, r9 @ normal exit from exception
+ beq concan_load @ no owner, skip save
+
+concan_save:
+
+ tmrc r2, wCon
+
+ @ CUP? wCx
+ tst r2, #0x1
+ beq 1f
+
+concan_dump:
+
+ wstrw wCSSF, [r1, #MMX_WCSSF]
+ wstrw wCASF, [r1, #MMX_WCASF]
+ wstrw wCGR0, [r1, #MMX_WCGR0]
+ wstrw wCGR1, [r1, #MMX_WCGR1]
+ wstrw wCGR2, [r1, #MMX_WCGR2]
+ wstrw wCGR3, [r1, #MMX_WCGR3]
+
+1: @ MUP? wRn
+ tst r2, #0x2
+ beq 2f
+
+ wstrd wR0, [r1, #MMX_WR0]
+ wstrd wR1, [r1, #MMX_WR1]
+ wstrd wR2, [r1, #MMX_WR2]
+ wstrd wR3, [r1, #MMX_WR3]
+ wstrd wR4, [r1, #MMX_WR4]
+ wstrd wR5, [r1, #MMX_WR5]
+ wstrd wR6, [r1, #MMX_WR6]
+ wstrd wR7, [r1, #MMX_WR7]
+ wstrd wR8, [r1, #MMX_WR8]
+ wstrd wR9, [r1, #MMX_WR9]
+ wstrd wR10, [r1, #MMX_WR10]
+ wstrd wR11, [r1, #MMX_WR11]
+ wstrd wR12, [r1, #MMX_WR12]
+ wstrd wR13, [r1, #MMX_WR13]
+ wstrd wR14, [r1, #MMX_WR14]
+ wstrd wR15, [r1, #MMX_WR15]
+
+2: teq r0, #0 @ anything to load?
+ moveq pc, lr
+
+concan_load:
+
+ @ Load wRn
+ wldrd wR0, [r0, #MMX_WR0]
+ wldrd wR1, [r0, #MMX_WR1]
+ wldrd wR2, [r0, #MMX_WR2]
+ wldrd wR3, [r0, #MMX_WR3]
+ wldrd wR4, [r0, #MMX_WR4]
+ wldrd wR5, [r0, #MMX_WR5]
+ wldrd wR6, [r0, #MMX_WR6]
+ wldrd wR7, [r0, #MMX_WR7]
+ wldrd wR8, [r0, #MMX_WR8]
+ wldrd wR9, [r0, #MMX_WR9]
+ wldrd wR10, [r0, #MMX_WR10]
+ wldrd wR11, [r0, #MMX_WR11]
+ wldrd wR12, [r0, #MMX_WR12]
+ wldrd wR13, [r0, #MMX_WR13]
+ wldrd wR14, [r0, #MMX_WR14]
+ wldrd wR15, [r0, #MMX_WR15]
+
+ @ Load wCx
+ wldrw wCSSF, [r0, #MMX_WCSSF]
+ wldrw wCASF, [r0, #MMX_WCASF]
+ wldrw wCGR0, [r0, #MMX_WCGR0]
+ wldrw wCGR1, [r0, #MMX_WCGR1]
+ wldrw wCGR2, [r0, #MMX_WCGR2]
+ wldrw wCGR3, [r0, #MMX_WCGR3]
+
+ @ clear CUP/MUP (only if r1 != 0)
+ teq r1, #0
+ mov r2, #0
+ moveq pc, lr
+ tmcr wCon, r2
+ mov pc, lr
+
+/*
+ * Back up Concan regs to save area and disable access to them
+ * (mainly for gdb or sleep mode usage)
+ *
+ * r0 = struct thread_info pointer of target task or NULL for any
+ */
+
+ENTRY(iwmmxt_task_disable)
+
+ stmfd sp!, {r4, lr}
+
+ mrs ip, cpsr
+ orr r2, ip, #PSR_I_BIT @ disable interrupts
+ msr cpsr_c, r2
+
+ ldr r3, =concan_owner
+ add r2, r0, #TI_IWMMXT_STATE @ get task Concan save area
+ ldr r1, [r3] @ get current Concan owner
+ teq r1, #0 @ any current owner?
+ beq 1f @ no: quit
+ teq r0, #0 @ any owner?
+ teqne r1, r2 @ or specified one?
+ bne 1f @ no: quit
+
+ mrc p15, 0, r4, c15, c1, 0
+ orr r4, r4, #0x3 @ enable access to CP0 and CP1
+ mcr p15, 0, r4, c15, c1, 0
+ mov r0, #0 @ nothing to load
+ str r0, [r3] @ no more current owner
+ mrc p15, 0, r2, c2, c0, 0
+ mov r2, r2 @ cpwait
+ bl concan_save
+
+ bic r4, r4, #0x3 @ disable access to CP0 and CP1
+ mcr p15, 0, r4, c15, c1, 0
+ mrc p15, 0, r2, c2, c0, 0
+ mov r2, r2 @ cpwait
+
+1: msr cpsr_c, ip @ restore interrupt mode
+ ldmfd sp!, {r4, pc}
+
+/*
+ * Copy Concan state to given memory address
+ *
+ * r0 = struct thread_info pointer of target task
+ * r1 = memory address where to store Concan state
+ *
+ * this is called mainly in the creation of signal stack frames
+ */
+
+ENTRY(iwmmxt_task_copy)
+
+ mrs ip, cpsr
+ orr r2, ip, #PSR_I_BIT @ disable interrupts
+ msr cpsr_c, r2
+
+ ldr r3, =concan_owner
+ add r2, r0, #TI_IWMMXT_STATE @ get task Concan save area
+ ldr r3, [r3] @ get current Concan owner
+ teq r2, r3 @ does this task own it...
+ beq 1f
+
+ @ current Concan values are in the task save area
+ msr cpsr_c, ip @ restore interrupt mode
+ mov r0, r1
+ mov r1, r2
+ mov r2, #MMX_SIZE
+ b memcpy
+
+1: @ this task owns Concan regs -- grab a copy from there
+ mov r0, #0 @ nothing to load
+ mov r2, #3 @ save all regs
+ mov r3, lr @ preserve return address
+ bl concan_dump
+ msr cpsr_c, ip @ restore interrupt mode
+ mov pc, r3
+
+/*
+ * Restore Concan state from given memory address
+ *
+ * r0 = struct thread_info pointer of target task
+ * r1 = memory address where to get Concan state from
+ *
+ * this is used to restore Concan state when unwinding a signal stack frame
+ */
+
+ENTRY(iwmmxt_task_restore)
+
+ mrs ip, cpsr
+ orr r2, ip, #PSR_I_BIT @ disable interrupts
+ msr cpsr_c, r2
+
+ ldr r3, =concan_owner
+ add r2, r0, #TI_IWMMXT_STATE @ get task Concan save area
+ ldr r3, [r3] @ get current Concan owner
+ bic r2, r2, #0x7 @ 64-bit alignment
+ teq r2, r3 @ does this task own it...
+ beq 1f
+
+ @ this task doesn't own Concan regs -- use its save area
+ msr cpsr_c, ip @ restore interrupt mode
+ mov r0, r2
+ mov r2, #MMX_SIZE
+ b memcpy
+
+1: @ this task owns Concan regs -- load them directly
+ mov r0, r1
+ mov r1, #0 @ don't clear CUP/MUP
+ mov r3, lr @ preserve return address
+ bl concan_load
+ msr cpsr_c, ip @ restore interrupt mode
+ mov pc, r3
+
+/*
+ * Concan handling on task switch
+ *
+ * r0 = previous task_struct pointer (must be preserved)
+ * r1 = previous thread_info pointer
+ * r2 = next thread_info.cpu_domain pointer (must be preserved)
+ *
+ * Called only from __switch_to with task preemption disabled.
+ * No need to care about preserving r4 and above.
+ */
+ENTRY(iwmmxt_task_switch)
+
+ mrc p15, 0, r4, c15, c1, 0
+ tst r4, #0x3 @ CP0 and CP1 accessible?
+ bne 1f @ yes: block them for next task
+
+ ldr r5, =concan_owner
+ add r6, r2, #(TI_IWMMXT_STATE - TI_CPU_DOMAIN) @ get next task Concan save area
+ ldr r5, [r5] @ get current Concan owner
+ teq r5, r6 @ next task owns it?
+ movne pc, lr @ no: leave Concan disabled
+
+1: eor r4, r4, #3 @ flip Concan access
+ mcr p15, 0, r4, c15, c1, 0
+
+ mrc p15, 0, r4, c2, c0, 0
+ sub pc, lr, r4, lsr #32 @ cpwait and return
+
+/*
+ * Remove Concan ownership of given task
+ *
+ * r0 = struct thread_info pointer
+ */
+ENTRY(iwmmxt_task_release)
+
+ mrs r2, cpsr
+ orr ip, r2, #PSR_I_BIT @ disable interrupts
+ msr cpsr_c, ip
+ ldr r3, =concan_owner
+ add r0, r0, #TI_IWMMXT_STATE @ get task Concan save area
+ ldr r1, [r3] @ get current Concan owner
+ eors r0, r0, r1 @ if equal...
+ streq r0, [r3] @ then clear ownership
+ msr cpsr_c, r2 @ restore interrupts
+ mov pc, lr
+
+ .data
+concan_owner:
+ .word 0
+