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linux/arch/arm/mach-omap2/sram242x.S
Paul Walmsley 1124d2f918 OMAP2/3: SRAM: add comment about crashes during a TLB miss 
Some users were observing crashes during the execution of CORE DVFS
code from OCM RAM -- a locally-modified copy of the linux-omap code.
Richard Woodruff tracked this down to a DTLB miss which had been
inadvertently and intermittently caused by the local modifications.
(The TLB miss caused the ARM MMU to attempt to walk the page tables
stored in SDRAM, which was not possible since SDRAM is off-line for a
portion of the CORE DVFS OCM RAM code.)

Add a note to the OMAP2 & OMAP3 CORE DVFS SRAM code to warn others that
changes may result in crashes here if they are not carefully tested.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Richard Woodruff <r-woodruff2@ti.com>
Cc: Jon Hunter <jon-hunter@ti.com>
Cc: Nishanth Menon <nm@ti.com>
2010-12-21 21:08:14 -07:00

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/*
* linux/arch/arm/mach-omap2/sram242x.S
*
* Omap2 specific functions that need to be run in internal SRAM
*
* (C) Copyright 2004
* Texas Instruments, <www.ti.com>
* Richard Woodruff <r-woodruff2@ti.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR /PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*
* Richard Woodruff notes that any changes to this code must be carefully
* audited and tested to ensure that they don't cause a TLB miss while
* the SDRAM is inaccessible. Such a situation will crash the system
* since it will cause the ARM MMU to attempt to walk the page tables.
* These crashes may be intermittent.
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <mach/io.h>
#include <mach/hardware.h>
#include "prm2xxx_3xxx.h"
#include "cm2xxx_3xxx.h"
#include "sdrc.h"
.text
ENTRY(omap242x_sram_ddr_init)
stmfd sp!, {r0 - r12, lr} @ save registers on stack
mov r12, r2 @ capture CS1 vs CS0
mov r8, r3 @ capture force parameter
/* frequency shift down */
ldr r2, omap242x_sdi_cm_clksel2_pll @ get address of dpllout reg
mov r3, #0x1 @ value for 1x operation
str r3, [r2] @ go to L1-freq operation
/* voltage shift down */
mov r9, #0x1 @ set up for L1 voltage call
bl voltage_shift @ go drop voltage
/* dll lock mode */
ldr r11, omap242x_sdi_sdrc_dlla_ctrl @ addr of dlla ctrl
ldr r10, [r11] @ get current val
cmp r12, #0x1 @ cs1 base (2422 es2.05/1)
addeq r11, r11, #0x8 @ if cs1 base, move to DLLB
mvn r9, #0x4 @ mask to get clear bit2
and r10, r10, r9 @ clear bit2 for lock mode.
orr r10, r10, #0x8 @ make sure DLL on (es2 bit pos)
orr r10, r10, #0x2 @ 90 degree phase for all below 133Mhz
str r10, [r11] @ commit to DLLA_CTRL
bl i_dll_wait @ wait for dll to lock
/* get dll value */
add r11, r11, #0x4 @ get addr of status reg
ldr r10, [r11] @ get locked value
/* voltage shift up */
mov r9, #0x0 @ shift back to L0-voltage
bl voltage_shift @ go raise voltage
/* frequency shift up */
mov r3, #0x2 @ value for 2x operation
str r3, [r2] @ go to L0-freq operation
/* reset entry mode for dllctrl */
sub r11, r11, #0x4 @ move from status to ctrl
cmp r12, #0x1 @ normalize if cs1 based
subeq r11, r11, #0x8 @ possibly back to DLLA
cmp r8, #0x1 @ if forced unlock exit
orreq r1, r1, #0x4 @ make sure exit with unlocked value
str r1, [r11] @ restore DLLA_CTRL high value
add r11, r11, #0x8 @ move to DLLB_CTRL addr
str r1, [r11] @ set value DLLB_CTRL
bl i_dll_wait @ wait for possible lock
/* set up for return, DDR should be good */
str r10, [r0] @ write dll_status and return counter
ldmfd sp!, {r0 - r12, pc} @ restore regs and return
/* ensure the DLL has relocked */
i_dll_wait:
mov r4, #0x800 @ delay DLL relock, min 0x400 L3 clocks
i_dll_delay:
subs r4, r4, #0x1
bne i_dll_delay
mov pc, lr
/*
* shift up or down voltage, use R9 as input to tell level.
* wait for it to finish, use 32k sync counter, 1tick=31uS.
*/
voltage_shift:
ldr r4, omap242x_sdi_prcm_voltctrl @ get addr of volt ctrl.
ldr r5, [r4] @ get value.
ldr r6, prcm_mask_val @ get value of mask
and r5, r5, r6 @ apply mask to clear bits
orr r5, r5, r9 @ bulld value for L0/L1-volt operation.
str r5, [r4] @ set up for change.
mov r3, #0x4000 @ get val for force
orr r5, r5, r3 @ build value for force
str r5, [r4] @ Force transition to L1
ldr r3, omap242x_sdi_timer_32ksynct_cr @ get addr of counter
ldr r5, [r3] @ get value
add r5, r5, #0x3 @ give it at most 93uS
volt_delay:
ldr r7, [r3] @ get timer value
cmp r5, r7 @ time up?
bhi volt_delay @ not yet->branch
mov pc, lr @ back to caller.
omap242x_sdi_cm_clksel2_pll:
.word OMAP2420_CM_REGADDR(PLL_MOD, CM_CLKSEL2)
omap242x_sdi_sdrc_dlla_ctrl:
.word OMAP242X_SDRC_REGADDR(SDRC_DLLA_CTRL)
omap242x_sdi_prcm_voltctrl:
.word OMAP2420_PRCM_VOLTCTRL
prcm_mask_val:
.word 0xFFFF3FFC
omap242x_sdi_timer_32ksynct_cr:
.word OMAP2_L4_IO_ADDRESS(OMAP2420_32KSYNCT_BASE + 0x010)
ENTRY(omap242x_sram_ddr_init_sz)
.word . - omap242x_sram_ddr_init
/*
* Reprograms memory timings.
* r0 = [PRCM_FULL | PRCM_HALF] r1 = SDRC_DLLA_CTRL value r2 = [DDR | SDR]
* PRCM_FULL = 2, PRCM_HALF = 1, DDR = 1, SDR = 0
*/
ENTRY(omap242x_sram_reprogram_sdrc)
stmfd sp!, {r0 - r10, lr} @ save registers on stack
mov r3, #0x0 @ clear for mrc call
mcr p15, 0, r3, c7, c10, 4 @ memory barrier, finish ARM SDR/DDR
nop
nop
ldr r6, omap242x_srs_sdrc_rfr_ctrl @ get addr of refresh reg
ldr r5, [r6] @ get value
mov r5, r5, lsr #8 @ isolate rfr field and drop burst
cmp r0, #0x1 @ going to half speed?
movne r9, #0x0 @ if up set flag up for pre up, hi volt
blne voltage_shift_c @ adjust voltage
cmp r0, #0x1 @ going to half speed (post branch link)
moveq r5, r5, lsr #1 @ divide by 2 if to half
movne r5, r5, lsl #1 @ mult by 2 if to full
mov r5, r5, lsl #8 @ put rfr field back into place
add r5, r5, #0x1 @ turn on burst of 1
ldr r4, omap242x_srs_cm_clksel2_pll @ get address of out reg
ldr r3, [r4] @ get curr value
orr r3, r3, #0x3
bic r3, r3, #0x3 @ clear lower bits
orr r3, r3, r0 @ new state value
str r3, [r4] @ set new state (pll/x, x=1 or 2)
nop
nop
moveq r9, #0x1 @ if speed down, post down, drop volt
bleq voltage_shift_c
mcr p15, 0, r3, c7, c10, 4 @ memory barrier
str r5, [r6] @ set new RFR_1 value
add r6, r6, #0x30 @ get RFR_2 addr
str r5, [r6] @ set RFR_2
nop
cmp r2, #0x1 @ (SDR or DDR) do we need to adjust DLL
bne freq_out @ leave if SDR, no DLL function
/* With DDR, we need to take care of the DLL for the frequency change */
ldr r2, omap242x_srs_sdrc_dlla_ctrl @ addr of dlla ctrl
str r1, [r2] @ write out new SDRC_DLLA_CTRL
add r2, r2, #0x8 @ addr to SDRC_DLLB_CTRL
str r1, [r2] @ commit to SDRC_DLLB_CTRL
mov r1, #0x2000 @ wait DLL relock, min 0x400 L3 clocks
dll_wait:
subs r1, r1, #0x1
bne dll_wait
freq_out:
ldmfd sp!, {r0 - r10, pc} @ restore regs and return
/*
* shift up or down voltage, use R9 as input to tell level.
* wait for it to finish, use 32k sync counter, 1tick=31uS.
*/
voltage_shift_c:
ldr r10, omap242x_srs_prcm_voltctrl @ get addr of volt ctrl
ldr r8, [r10] @ get value
ldr r7, ddr_prcm_mask_val @ get value of mask
and r8, r8, r7 @ apply mask to clear bits
orr r8, r8, r9 @ bulld value for L0/L1-volt operation.
str r8, [r10] @ set up for change.
mov r7, #0x4000 @ get val for force
orr r8, r8, r7 @ build value for force
str r8, [r10] @ Force transition to L1
ldr r10, omap242x_srs_timer_32ksynct @ get addr of counter
ldr r8, [r10] @ get value
add r8, r8, #0x2 @ give it at most 62uS (min 31+)
volt_delay_c:
ldr r7, [r10] @ get timer value
cmp r8, r7 @ time up?
bhi volt_delay_c @ not yet->branch
mov pc, lr @ back to caller
omap242x_srs_cm_clksel2_pll:
.word OMAP2420_CM_REGADDR(PLL_MOD, CM_CLKSEL2)
omap242x_srs_sdrc_dlla_ctrl:
.word OMAP242X_SDRC_REGADDR(SDRC_DLLA_CTRL)
omap242x_srs_sdrc_rfr_ctrl:
.word OMAP242X_SDRC_REGADDR(SDRC_RFR_CTRL_0)
omap242x_srs_prcm_voltctrl:
.word OMAP2420_PRCM_VOLTCTRL
ddr_prcm_mask_val:
.word 0xFFFF3FFC
omap242x_srs_timer_32ksynct:
.word OMAP2_L4_IO_ADDRESS(OMAP2420_32KSYNCT_BASE + 0x010)
ENTRY(omap242x_sram_reprogram_sdrc_sz)
.word . - omap242x_sram_reprogram_sdrc
/*
* Set dividers and pll. Also recalculate DLL value for DDR and unlock mode.
*/
ENTRY(omap242x_sram_set_prcm)
stmfd sp!, {r0-r12, lr} @ regs to stack
adr r4, pbegin @ addr of preload start
adr r8, pend @ addr of preload end
mcrr p15, 1, r8, r4, c12 @ preload into icache
pbegin:
/* move into fast relock bypass */
ldr r8, omap242x_ssp_pll_ctl @ get addr
ldr r5, [r8] @ get val
mvn r6, #0x3 @ clear mask
and r5, r5, r6 @ clear field
orr r7, r5, #0x2 @ fast relock val
str r7, [r8] @ go to fast relock
ldr r4, omap242x_ssp_pll_stat @ addr of stat
block:
/* wait for bypass */
ldr r8, [r4] @ stat value
and r8, r8, #0x3 @ mask for stat
cmp r8, #0x1 @ there yet
bne block @ loop if not
/* set new dpll dividers _after_ in bypass */
ldr r4, omap242x_ssp_pll_div @ get addr
str r0, [r4] @ set dpll ctrl val
ldr r4, omap242x_ssp_set_config @ get addr
mov r8, #1 @ valid cfg msk
str r8, [r4] @ make dividers take
mov r4, #100 @ dead spin a bit
wait_a_bit:
subs r4, r4, #1 @ dec loop
bne wait_a_bit @ delay done?
/* check if staying in bypass */
cmp r2, #0x1 @ stay in bypass?
beq pend @ jump over dpll relock
/* relock DPLL with new vals */
ldr r5, omap242x_ssp_pll_stat @ get addr
ldr r4, omap242x_ssp_pll_ctl @ get addr
orr r8, r7, #0x3 @ val for lock dpll
str r8, [r4] @ set val
mov r0, #1000 @ dead spin a bit
wait_more:
subs r0, r0, #1 @ dec loop
bne wait_more @ delay done?
wait_lock:
ldr r8, [r5] @ get lock val
and r8, r8, #3 @ isolate field
cmp r8, #2 @ locked?
bne wait_lock @ wait if not
pend:
/* update memory timings & briefly lock dll */
ldr r4, omap242x_ssp_sdrc_rfr @ get addr
str r1, [r4] @ update refresh timing
ldr r11, omap242x_ssp_dlla_ctrl @ get addr of DLLA ctrl
ldr r10, [r11] @ get current val
mvn r9, #0x4 @ mask to get clear bit2
and r10, r10, r9 @ clear bit2 for lock mode
orr r10, r10, #0x8 @ make sure DLL on (es2 bit pos)
str r10, [r11] @ commit to DLLA_CTRL
add r11, r11, #0x8 @ move to dllb
str r10, [r11] @ hit DLLB also
mov r4, #0x800 @ relock time (min 0x400 L3 clocks)
wait_dll_lock:
subs r4, r4, #0x1
bne wait_dll_lock
nop
ldmfd sp!, {r0-r12, pc} @ restore regs and return
omap242x_ssp_set_config:
.word OMAP2420_PRCM_CLKCFG_CTRL
omap242x_ssp_pll_ctl:
.word OMAP2420_CM_REGADDR(PLL_MOD, CM_CLKEN)
omap242x_ssp_pll_stat:
.word OMAP2420_CM_REGADDR(PLL_MOD, CM_IDLEST)
omap242x_ssp_pll_div:
.word OMAP2420_CM_REGADDR(PLL_MOD, CM_CLKSEL1)
omap242x_ssp_sdrc_rfr:
.word OMAP242X_SDRC_REGADDR(SDRC_RFR_CTRL_0)
omap242x_ssp_dlla_ctrl:
.word OMAP242X_SDRC_REGADDR(SDRC_DLLA_CTRL)
ENTRY(omap242x_sram_set_prcm_sz)
.word . - omap242x_sram_set_prcm
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