arch/arm/mach-mvebu/coherency_ll.S

   1 /*
   2  * Coherency fabric: low level functions
   3  *
   4  * Copyright (C) 2012 Marvell
   5  *
   6  * Gregory CLEMENT <gregory.clement@free-electrons.com>
   7  *
   8  * This file is licensed under the terms of the GNU General Public
   9  * License version 2.  This program is licensed "as is" without any
  10  * warranty of any kind, whether express or implied.
  11  *
  12  * This file implements the assembly function to add a CPU to the
  13  * coherency fabric. This function is called by each of the secondary
  14  * CPUs during their early boot in an SMP kernel, this why this
  15  * function have to callable from assembly. It can also be called by a
  16  * primary CPU from C code during its boot.
  17  */
  18
  19 #include <linux/linkage.h>
  20 #define ARMADA_XP_CFB_CTL_REG_OFFSET 0x0
  21 #define ARMADA_XP_CFB_CFG_REG_OFFSET 0x4
  22
  23         .text
  24 /*
  25  * r0: Coherency fabric base register address
  26  * r1: HW CPU id
  27  */
  28 ENTRY(ll_set_cpu_coherent)
  29         /* Create bit by cpu index */
  30         mov     r3, #(1 << 24)
  31         lsl     r1, r3, r1
  32
  33         /* Add CPU to SMP group - Atomic */
  34         add     r3, r0, #ARMADA_XP_CFB_CTL_REG_OFFSET
  35 1:
  36         ldrex   r2, [r3]
  37         orr     r2, r2, r1
  38         strex   r0, r2, [r3]
  39         cmp     r0, #0
  40         bne 1b
  41
  42         /* Enable coherency on CPU - Atomic */
  43         add     r3, r3, #ARMADA_XP_CFB_CFG_REG_OFFSET
  44 1:
  45         ldrex   r2, [r3]
  46         orr     r2, r2, r1
  47         strex   r0, r2, [r3]
  48         cmp     r0, #0
  49         bne 1b
  50
  51         dsb
  52
  53         mov     r0, #0
  54         mov     pc, lr
  55 ENDPROC(ll_set_cpu_coherent)