arch/arm/plat-omap/sram-fn.S

   1 /*
   2  * linux/arch/arm/plat-omap/sram-fn.S
   3  *
   4  * Functions that need to be run in internal SRAM
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/linkage.h>
  12 #include <asm/assembler.h>
  13 #include <asm/arch/io.h>
  14 #include <asm/hardware.h>
  15
  16         .text
  17
  18 /*
  19  * Reprograms ULPD and CKCTL.
  20  */
  21 ENTRY(sram_reprogram_clock)
  22         stmfd   sp!, {r0 - r12, lr}             @ save registers on stack
  23
  24         mov     r2, #IO_ADDRESS(DPLL_CTL) & 0xff000000
  25         orr     r2, r2, #IO_ADDRESS(DPLL_CTL) & 0x00ff0000
  26         orr     r2, r2, #IO_ADDRESS(DPLL_CTL) & 0x0000ff00
  27
  28         mov     r3, #IO_ADDRESS(ARM_CKCTL) & 0xff000000
  29         orr     r3, r3, #IO_ADDRESS(ARM_CKCTL) & 0x00ff0000
  30         orr     r3, r3, #IO_ADDRESS(ARM_CKCTL) & 0x0000ff00
  31
  32         tst     r0, #1 << 4                     @ want lock mode?
  33         beq     newck                           @ nope
  34         bic     r0, r0, #1 << 4                 @ else clear lock bit
  35         strh    r0, [r2]                        @ set dpll into bypass mode
  36         orr     r0, r0, #1 << 4                 @ set lock bit again
  37
  38 newck:
  39         strh    r1, [r3]                        @ write new ckctl value
  40         strh    r0, [r2]                        @ write new dpll value
  41
  42         mov     r4, #0x0700                     @ let the clocks settle
  43         orr     r4, r4, #0x00ff
  44 delay:  sub     r4, r4, #1
  45         cmp     r4, #0
  46         bne     delay
  47
  48 lock:   ldrh    r4, [r2], #0                    @ read back dpll value
  49         tst     r0, #1 << 4                     @ want lock mode?
  50         beq     out                             @ nope
  51         tst     r4, #1 << 0                     @ dpll rate locked?
  52         beq     lock                            @ try again
  53
  54 out:
  55         ldmfd   sp!, {r0 - r12, pc}             @ restore regs and return
  56 ENTRY(sram_reprogram_clock_sz)
  57         .word   . - sram_reprogram_clock