1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * Coherency fabric: low level functions 4 * 5 * Copyright (C) 2012 Marvell 6 * 7 * Gregory CLEMENT <gregory.clement@free-electrons.com> 8 * 9 * This file implements the assembly function to add a CPU to the 10 * coherency fabric. This function is called by each of the secondary 11 * CPUs during their early boot in an SMP kernel, this why this 12 * function have to callable from assembly. It can also be called by a 13 * primary CPU from C code during its boot. 14 */ 15 16 #include <linux/linkage.h> 17 #define ARMADA_XP_CFB_CTL_REG_OFFSET 0x0 18 #define ARMADA_XP_CFB_CFG_REG_OFFSET 0x4 19 20 #include <asm/assembler.h> 21 #include <asm/cp15.h> 22 23 .arch armv7-a 24 .text 25 /* 26 * Returns the coherency base address in r1 (r0 is untouched), or 0 if 27 * the coherency fabric is not enabled. 28 */ 29 ENTRY(ll_get_coherency_base) 30 mrc p15, 0, r1, c1, c0, 0 31 tst r1, #CR_M @ Check MMU bit enabled 32 bne 1f 33 34 /* 35 * MMU is disabled, use the physical address of the coherency 36 * base address, (or 0x0 if the coherency fabric is not mapped) 37 */ 38 adr r1, 3f 39 ldr r3, [r1] 40 ldr r1, [r1, r3] 41 b 2f 42 1: 43 /* 44 * MMU is enabled, use the virtual address of the coherency 45 * base address. 46 */ 47 ldr r1, =coherency_base 48 ldr r1, [r1] 49 2: 50 ret lr 51 ENDPROC(ll_get_coherency_base) 52 53 /* 54 * Returns the coherency CPU mask in r3 (r0 is untouched). This 55 * coherency CPU mask can be used with the coherency fabric 56 * configuration and control registers. Note that the mask is already 57 * endian-swapped as appropriate so that the calling functions do not 58 * have to care about endianness issues while accessing the coherency 59 * fabric registers 60 */ 61 ENTRY(ll_get_coherency_cpumask) 62 mrc p15, 0, r3, cr0, cr0, 5 63 and r3, r3, #15 64 mov r2, #(1 << 24) 65 lsl r3, r2, r3 66 ARM_BE8(rev r3, r3) 67 ret lr 68 ENDPROC(ll_get_coherency_cpumask) 69 70 /* 71 * ll_add_cpu_to_smp_group(), ll_enable_coherency() and 72 * ll_disable_coherency() use the strex/ldrex instructions while the 73 * MMU can be disabled. The Armada XP SoC has an exclusive monitor 74 * that tracks transactions to Device and/or SO memory and thanks to 75 * that, exclusive transactions are functional even when the MMU is 76 * disabled. 77 */ 78 79 ENTRY(ll_add_cpu_to_smp_group) 80 /* 81 * As r0 is not modified by ll_get_coherency_base() and 82 * ll_get_coherency_cpumask(), we use it to temporarly save lr 83 * and avoid it being modified by the branch and link 84 * calls. This function is used very early in the secondary 85 * CPU boot, and no stack is available at this point. 86 */ 87 mov r0, lr 88 bl ll_get_coherency_base 89 /* Bail out if the coherency is not enabled */ 90 cmp r1, #0 91 reteq r0 92 bl ll_get_coherency_cpumask 93 mov lr, r0 94 add r0, r1, #ARMADA_XP_CFB_CFG_REG_OFFSET 95 1: 96 ldrex r2, [r0] 97 orr r2, r2, r3 98 strex r1, r2, [r0] 99 cmp r1, #0 100 bne 1b 101 ret lr 102 ENDPROC(ll_add_cpu_to_smp_group) 103 104 ENTRY(ll_enable_coherency) 105 /* 106 * As r0 is not modified by ll_get_coherency_base() and 107 * ll_get_coherency_cpumask(), we use it to temporarly save lr 108 * and avoid it being modified by the branch and link 109 * calls. This function is used very early in the secondary 110 * CPU boot, and no stack is available at this point. 111 */ 112 mov r0, lr 113 bl ll_get_coherency_base 114 /* Bail out if the coherency is not enabled */ 115 cmp r1, #0 116 reteq r0 117 bl ll_get_coherency_cpumask 118 mov lr, r0 119 add r0, r1, #ARMADA_XP_CFB_CTL_REG_OFFSET 120 1: 121 ldrex r2, [r0] 122 orr r2, r2, r3 123 strex r1, r2, [r0] 124 cmp r1, #0 125 bne 1b 126 dsb 127 mov r0, #0 128 ret lr 129 ENDPROC(ll_enable_coherency) 130 131 ENTRY(ll_disable_coherency) 132 /* 133 * As r0 is not modified by ll_get_coherency_base() and 134 * ll_get_coherency_cpumask(), we use it to temporarly save lr 135 * and avoid it being modified by the branch and link 136 * calls. This function is used very early in the secondary 137 * CPU boot, and no stack is available at this point. 138 */ 139 mov r0, lr 140 bl ll_get_coherency_base 141 /* Bail out if the coherency is not enabled */ 142 cmp r1, #0 143 reteq r0 144 bl ll_get_coherency_cpumask 145 mov lr, r0 146 add r0, r1, #ARMADA_XP_CFB_CTL_REG_OFFSET 147 1: 148 ldrex r2, [r0] 149 bic r2, r2, r3 150 strex r1, r2, [r0] 151 cmp r1, #0 152 bne 1b 153 dsb 154 ret lr 155 ENDPROC(ll_disable_coherency) 156 157 .align 2 158 3: 159 .long coherency_phys_base - . 160