arch/arm/mach-omap1/sram.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
  13 #include <asm/assembler.h>
  14
  15 #include <mach/hardware.h>
  16
  17 #include "iomap.h"
  18
  19         .text
  20
  21 /*
  22  * Reprograms ULPD and CKCTL.
  23  */
  24         .align  3
  25 ENTRY(omap1_sram_reprogram_clock)
  26         stmfd   sp!, {r0 - r12, lr}             @ save registers on stack
  27
  28         mov     r2, #OMAP1_IO_ADDRESS(DPLL_CTL) & 0xff000000
  29         orr     r2, r2, #OMAP1_IO_ADDRESS(DPLL_CTL) & 0x00ff0000
  30         orr     r2, r2, #OMAP1_IO_ADDRESS(DPLL_CTL) & 0x0000ff00
  31
  32         mov     r3, #OMAP1_IO_ADDRESS(ARM_CKCTL) & 0xff000000
  33         orr     r3, r3, #OMAP1_IO_ADDRESS(ARM_CKCTL) & 0x00ff0000
  34         orr     r3, r3, #OMAP1_IO_ADDRESS(ARM_CKCTL) & 0x0000ff00
  35
  36         tst     r0, #1 << 4                     @ want lock mode?
  37         beq     newck                           @ nope
  38         bic     r0, r0, #1 << 4                 @ else clear lock bit
  39         strh    r0, [r2]                        @ set dpll into bypass mode
  40         orr     r0, r0, #1 << 4                 @ set lock bit again
  41
  42 newck:
  43         strh    r1, [r3]                        @ write new ckctl value
  44         strh    r0, [r2]                        @ write new dpll value
  45
  46         mov     r4, #0x0700                     @ let the clocks settle
  47         orr     r4, r4, #0x00ff
  48 delay:  sub     r4, r4, #1
  49         cmp     r4, #0
  50         bne     delay
  51
  52 lock:   ldrh    r4, [r2], #0                    @ read back dpll value
  53         tst     r0, #1 << 4                     @ want lock mode?
  54         beq     out                             @ nope
  55         tst     r4, #1 << 0                     @ dpll rate locked?
  56         beq     lock                            @ try again
  57
  58 out:
  59         ldmfd   sp!, {r0 - r12, pc}             @ restore regs and return
  60 ENTRY(omap1_sram_reprogram_clock_sz)
  61         .word   . - omap1_sram_reprogram_clock