07ae144be1
In the refactoring of the coherency fabric assembly code, a function called ll_get_cpuid() was created to factorize common logic between functions adding CPU to the SMP coherency group, enabling and disabling the coherency. However, the name of the function is highly misleading: ll_get_cpuid() makes one think tat it returns the ID of the CPU, i.e 0 for CPU0, 1 for CPU1, etc. In fact, this is not at all what this function returns: it returns a CPU mask for the current CPU, usable for the coherency fabric configuration and control registers. Therefore this commit renames this function to ll_get_coherency_cpumask(), and adds additional comments on top of the function to explain in more details what it does, and also how the endianess issue is handled. Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Link: https://lkml.kernel.org/r/1400762882-10116-5-git-send-email-thomas.petazzoni@free-electrons.com Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com> Signed-off-by: Jason Cooper <jason@lakedaemon.net>
149 lines
3.9 KiB
ArmAsm
149 lines
3.9 KiB
ArmAsm
/*
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* Coherency fabric: low level functions
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*
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* Copyright (C) 2012 Marvell
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*
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* Gregory CLEMENT <gregory.clement@free-electrons.com>
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*
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* This file is licensed under the terms of the GNU General Public
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* License version 2. This program is licensed "as is" without any
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* warranty of any kind, whether express or implied.
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*
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* This file implements the assembly function to add a CPU to the
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* coherency fabric. This function is called by each of the secondary
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* CPUs during their early boot in an SMP kernel, this why this
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* function have to callable from assembly. It can also be called by a
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* primary CPU from C code during its boot.
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*/
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#include <linux/linkage.h>
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#define ARMADA_XP_CFB_CTL_REG_OFFSET 0x0
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#define ARMADA_XP_CFB_CFG_REG_OFFSET 0x4
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#include <asm/assembler.h>
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#include <asm/cp15.h>
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.text
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/* Returns the coherency base address in r1 (r0 is untouched) */
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ENTRY(ll_get_coherency_base)
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mrc p15, 0, r1, c1, c0, 0
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tst r1, #CR_M @ Check MMU bit enabled
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bne 1f
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/*
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* MMU is disabled, use the physical address of the coherency
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* base address.
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*/
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adr r1, 3f
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ldr r3, [r1]
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ldr r1, [r1, r3]
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b 2f
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1:
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/*
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* MMU is enabled, use the virtual address of the coherency
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* base address.
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*/
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ldr r1, =coherency_base
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ldr r1, [r1]
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2:
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mov pc, lr
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ENDPROC(ll_get_coherency_base)
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/*
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* Returns the coherency CPU mask in r3 (r0 is untouched). This
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* coherency CPU mask can be used with the coherency fabric
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* configuration and control registers. Note that the mask is already
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* endian-swapped as appropriate so that the calling functions do not
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* have to care about endianness issues while accessing the coherency
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* fabric registers
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*/
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ENTRY(ll_get_coherency_cpumask)
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mrc 15, 0, r3, cr0, cr0, 5
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and r3, r3, #15
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mov r2, #(1 << 24)
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lsl r3, r2, r3
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ARM_BE8(rev r3, r3)
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mov pc, lr
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ENDPROC(ll_get_coherency_cpumask)
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/*
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* ll_add_cpu_to_smp_group(), ll_enable_coherency() and
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* ll_disable_coherency() use the strex/ldrex instructions while the
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* MMU can be disabled. The Armada XP SoC has an exclusive monitor
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* that tracks transactions to Device and/or SO memory and thanks to
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* that, exclusive transactions are functional even when the MMU is
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* disabled.
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*/
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ENTRY(ll_add_cpu_to_smp_group)
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/*
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* As r0 is not modified by ll_get_coherency_base() and
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* ll_get_coherency_cpumask(), we use it to temporarly save lr
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* and avoid it being modified by the branch and link
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* calls. This function is used very early in the secondary
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* CPU boot, and no stack is available at this point.
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*/
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mov r0, lr
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bl ll_get_coherency_base
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bl ll_get_coherency_cpumask
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mov lr, r0
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add r0, r1, #ARMADA_XP_CFB_CFG_REG_OFFSET
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1:
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ldrex r2, [r0]
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orr r2, r2, r3
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strex r1, r2, [r0]
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cmp r1, #0
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bne 1b
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mov pc, lr
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ENDPROC(ll_add_cpu_to_smp_group)
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ENTRY(ll_enable_coherency)
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/*
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* As r0 is not modified by ll_get_coherency_base() and
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* ll_get_coherency_cpumask(), we use it to temporarly save lr
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* and avoid it being modified by the branch and link
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* calls. This function is used very early in the secondary
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* CPU boot, and no stack is available at this point.
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*/
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mov r0, lr
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bl ll_get_coherency_base
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bl ll_get_coherency_cpumask
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mov lr, r0
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add r0, r1, #ARMADA_XP_CFB_CTL_REG_OFFSET
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1:
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ldrex r2, [r0]
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orr r2, r2, r3
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strex r1, r2, [r0]
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cmp r1, #0
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bne 1b
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dsb
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mov r0, #0
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mov pc, lr
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ENDPROC(ll_enable_coherency)
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ENTRY(ll_disable_coherency)
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/*
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* As r0 is not modified by ll_get_coherency_base() and
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* ll_get_coherency_cpumask(), we use it to temporarly save lr
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* and avoid it being modified by the branch and link
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* calls. This function is used very early in the secondary
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* CPU boot, and no stack is available at this point.
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*/
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mov r0, lr
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bl ll_get_coherency_base
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bl ll_get_coherency_cpumask
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mov lr, r0
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add r0, r1, #ARMADA_XP_CFB_CTL_REG_OFFSET
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1:
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ldrex r2, [r0]
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bic r2, r2, r3
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strex r1, r2, [r0]
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cmp r1, #0
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bne 1b
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dsb
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mov pc, lr
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ENDPROC(ll_disable_coherency)
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.align 2
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3:
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.long coherency_phys_base - .
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