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Once you have made an election to distribute the File under one of the following license alternatives, please (i) delete this introductory statement regarding license alternatives, (ii) delete the two license alternatives that you have not elected to use and (iii) preserve the Marvell copyright notice above. ******************************************************************************** Marvell Commercial License Option If you received this File from Marvell and you have entered into a commercial license agreement (a "Commercial License") with Marvell, the File is licensed to you under the terms of the applicable Commercial License. ******************************************************************************** Marvell GPL License Option If you received this File from Marvell, you may opt to use, redistribute and/or modify this File in accordance with the terms and conditions of the General Public License Version 2, June 1991 (the "GPL License"), a copy of which is available along with the File in the license.txt file or by writing to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 or on the worldwide web at http://www.gnu.org/licenses/gpl.txt. THE FILE IS DISTRIBUTED AS-IS, WITHOUT WARRANTY OF ANY KIND, AND THE IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY DISCLAIMED. The GPL License provides additional details about this warranty disclaimer. ******************************************************************************** Marvell BSD License Option If you received this File from Marvell, you may opt to use, redistribute and/or modify this File under the following licensing terms. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. * Neither the name of Marvell nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. *******************************************************************************/ /******************************************************************************* * mvDramIfBasicAsm.s * * DESCRIPTION: * Memory full detection and best timing configuration is done in * C code. C runtime environment requires a stack. This module API * initialize DRAM interface chip select 0 for basic functionality for * the use of stack. * The module API assumes DRAM information is stored in I2C EEPROM reside * in a given I2C address MV_BOARD_DIMM0_I2C_ADDR. The I2C EEPROM * internal data structure is assumed to be orgenzied in common DRAM * vendor SPD structure. * NOTE: DFCDL values are assumed to be already initialized prior to * this module API activity. * * * DEPENDENCIES: * None. * *******************************************************************************/ /* includes */ #define MV_ASMLANGUAGE #include "mvOsAsm.h" #include "mvSysHwConfig.h" #include "mvDramIfRegs.h" #include "mvDramIfConfig.h" #include "mvCpuIfRegs.h" #include "pex/mvPexRegs.h" #include "pci/mvPciRegs.h" #include "mvCtrlEnvSpec.h" #include "mvCtrlEnvAsm.h" #include "cpu/mvCpuArm.h" #include "mvCommon.h" /* defines */ /* locals */ .data .globl _mvDramIfConfig .text /******************************************************************************* * _mvDramIfConfig - Basic DRAM interface initialization. * * DESCRIPTION: * The function will initialize the following DRAM parameters using the * values prepared by mvDramIfDetect routine. Values are located * in predefined registers. * * INPUT: * None. * * OUTPUT: * None. * * RETURN: * None. * *******************************************************************************/ _mvDramIfConfig: /* Save register on stack */ cmp sp, #0 beq no_stack_s save_on_stack: stmdb sp!, {r1, r2, r3, r4, r7, r11} no_stack_s: /* 1) Write to SDRAM coniguration register */ ldr r1, =(INTER_REGS_BASE + DRAM_BUF_REG1) ldr r4, [r1] ldr r1, =(INTER_REGS_BASE + SDRAM_CONFIG_REG) str r4, [r1] /* 2) Write Dunit control low register */ ldr r1, =(INTER_REGS_BASE + DRAM_BUF_REG3) ldr r4, [r1] ldr r1, =(INTER_REGS_BASE + SDRAM_DUNIT_CTRL_REG) str r4, [r1] /* 3) Write SDRAM address control register */ ldr r1, =(INTER_REGS_BASE + DRAM_BUF_REG4) ldr r4, [r1] ldr r1, =(INTER_REGS_BASE + SDRAM_ADDR_CTRL_REG) str r4, [r1] /* 4) Write SDRAM bank 0 size register */ ldr r1, =(INTER_REGS_BASE + DRAM_BUF_REG0) ldr r4, [r1] ldr r1, =(INTER_REGS_BASE + SDRAM_SIZE_REG(0)) str r4, [r1] /* 5) Write SDRAM open pages control register */ ldr r1, =(INTER_REGS_BASE + SDRAM_OPEN_PAGE_CTRL_REG) ldr r4, =SDRAM_OPEN_PAGES_CTRL_REG_DV str r4, [r1] /* 6) Write SDRAM timing Low register */ ldr r1, =(INTER_REGS_BASE + DRAM_BUF_REG5) ldr r4, [r1] ldr r1, =(INTER_REGS_BASE + SDRAM_TIMING_CTRL_LOW_REG) str r4, [r1] /* 7) Write SDRAM timing High register */ ldr r1, =(INTER_REGS_BASE + DRAM_BUF_REG6) ldr r4, [r1] ldr r1, =(INTER_REGS_BASE + SDRAM_TIMING_CTRL_HIGH_REG) str r4, [r1] /* 8) Write SDRAM mode register */ /* The CPU must not attempt to change the SDRAM Mode register setting */ /* prior to DRAM controller completion of the DRAM initialization */ /* sequence. To guarantee this restriction, it is recommended that */ /* the CPU sets the SDRAM Operation register to NOP command, performs */ /* read polling until the register is back in Normal operation value, */ /* and then sets SDRAM Mode register to it’s new value. */ /* 8.1 write 'nop' to SDRAM operation */ mov r4, #0x5 /* 'NOP' command */ MV_REG_WRITE_ASM(r4, r1, SDRAM_OPERATION_REG) /* 8.2 poll SDRAM operation. Make sure its back to normal operation */ _sdramOpPoll1: ldr r4, [r1] cmp r4, #0 /* '0' = Normal SDRAM Mode */ bne _sdramOpPoll1 /* 8.3 Now its safe to write new value to SDRAM Mode register */ ldr r1, =(INTER_REGS_BASE + DRAM_BUF_REG2) ldr r4, [r1] ldr r1, =(INTER_REGS_BASE + SDRAM_MODE_REG) str r4, [r1] /* 8.4 Make the Dunit write the DRAM its new mode */ mov r4, #0x3 /* Mode Register Set command */ MV_REG_WRITE_ASM (r4, r1, SDRAM_OPERATION_REG) /* 8.5 poll SDRAM operation. Make sure its back to normal operation */ _sdramOpPoll2: ldr r4, [r1] cmp r4, #0 /* '0' = Normal SDRAM Mode */ bne _sdramOpPoll2 #ifndef DB_FPGA /* Config DDR2 registers (Extended mode, ODTs and pad calibration) */ MV_REG_READ_ASM (r4, r1, SDRAM_CONFIG_REG) tst r4, #SDRAM_DTYPE_DDR2 beq _extModeODTEnd #endif /* DB_FPGA */ /* 9) Write SDRAM Extended mode register This operation should be */ /* done for each memory bank */ /* write 'nop' to SDRAM operation */ mov r4, #0x5 /* 'NOP' command */ MV_REG_WRITE_ASM (r4, r1, SDRAM_OPERATION_REG) /* poll SDRAM operation. Make sure its back to normal operation */ _sdramOpPoll3: ldr r4, [r1] cmp r4, #0 /* '0' = Normal SDRAM Mode */ bne _sdramOpPoll3 /* Now its safe to write new value to SDRAM Extended Mode register */ ldr r1, =(INTER_REGS_BASE + DRAM_BUF_REG10) ldr r4, [r1] ldr r1, =(INTER_REGS_BASE + SDRAM_EXTENDED_MODE_REG) str r4, [r1] /* Go over each of the Banks */ ldr r3, =0 /* r3 = DRAM bank Num */ extModeLoop: /* Set the SDRAM Operation Control to each of the DRAM banks */ mov r2, r3 /* Do not swap the bank counter value */ MV_REG_WRITE_ASM (r2, r1, SDRAM_OPERATION_CTRL_REG) /* Make the Dunit write the DRAM its new mode */ mov r4, #0x4 /* Extended Mode Register Set command */ MV_REG_WRITE_ASM (r4, r1, SDRAM_OPERATION_REG) /* poll SDRAM operation. Make sure its back to normal operation */ _sdramOpPoll4: ldr r4, [r1] cmp r4, #0 /* '0' = Normal SDRAM Mode */ bne _sdramOpPoll4 #ifndef DB_FPGA add r3, r3, #1 cmp r3, #4 /* 4 = Number of banks */ bne extModeLoop extModeEnd: /* Config DDR2 On Die Termination (ODT) registers */ /* Write SDRAM DDR2 ODT control low register */ ldr r1, =(INTER_REGS_BASE + DRAM_BUF_REG7) ldr r4, [r1] ldr r1, =(INTER_REGS_BASE + DDR2_SDRAM_ODT_CTRL_LOW_REG) str r4, [r1] /* Write SDRAM DDR2 ODT control high register */ ldr r1, =(INTER_REGS_BASE + DRAM_BUF_REG8) ldr r4, [r1] ldr r1, =(INTER_REGS_BASE + DDR2_SDRAM_ODT_CTRL_HIGH_REG) str r4, [r1] /* Write SDRAM DDR2 Dunit ODT control register */ ldr r1, =(INTER_REGS_BASE + DRAM_BUF_REG9) ldr r4, [r1] ldr r1, =(INTER_REGS_BASE + DDR2_DUNIT_ODT_CONTROL_REG) str r4, [r1] #endif /* DB_FPGA */ _extModeODTEnd: #ifndef DB_FPGA /* Implement Guideline (GL# MEM-2) P_CAL Automatic Calibration */ /* Does Not Work for Address/Control and Data Pads. */ /* Relevant for: 88F5181-A1/B0 and 88F5281-A0 */ /* Read device ID */ MV_CTRL_MODEL_GET_ASM(r3, r1); /* Read device revision */ MV_CTRL_REV_GET_ASM(r2, r1); /* Continue if OrionN */ ldr r1, =MV_5180_DEV_ID cmp r3, r1 bne 1f b glMem2End 1: /* Continue if Orion1 and device revision B1 */ ldr r1, =MV_5181_DEV_ID cmp r3, r1 bne 1f cmp r2, #MV_5181_B1_REV bge glMem2End b glMem2Start 1: /* Orion NAS */ ldr r1, =MV_5182_DEV_ID cmp r3, r1 beq glMem2Start /* Orion NAS */ ldr r1, =MV_5082_DEV_ID cmp r3, r1 beq glMem2Start /* Orion Shark */ ldr r1, =MV_8660_DEV_ID cmp r3, r1 beq glMem2Start b glMem2End glMem2Start: /* DDR SDRAM Address/Control Pads Calibration */ MV_REG_READ_ASM (r3, r1, SDRAM_ADDR_CTRL_PADS_CAL_REG) /* Set Bit [31] to make the register writable */ orr r2, r3, #SDRAM_WR_EN MV_REG_WRITE_ASM (r2, r1, SDRAM_ADDR_CTRL_PADS_CAL_REG) bic r3, r3, #SDRAM_WR_EN /* Make register read-only */ bic r3, r3, #SDRAM_TUNE_EN /* Disable auto calibration */ bic r3, r3, #SDRAM_DRVN_MASK /* Clear r1[5:0] */ bic r3, r3, #SDRAM_DRVP_MASK /* Clear r1[11:6] */ /* Get the final N locked value of driving strength [22:17] */ mov r1, r3 mov r1, r1, LSL #9 mov r1, r1, LSR #26 /* r1[5:0] = r3[22:17] */ orr r1, r1, r1, LSL #6 /* r1[11:6] = r1[5:0] */ /* Write to both bits [5:0] and bits [11:6] */ orr r3, r3, r1 MV_REG_WRITE_ASM (r3, r1, SDRAM_ADDR_CTRL_PADS_CAL_REG) /* DDR SDRAM Data Pads Calibration */ MV_REG_READ_ASM (r3, r1, SDRAM_DATA_PADS_CAL_REG) /* Set Bit [31] to make the register writable */ orr r2, r3, #SDRAM_WR_EN MV_REG_WRITE_ASM (r2, r1, SDRAM_DATA_PADS_CAL_REG) bic r3, r3, #SDRAM_WR_EN /* Make register read-only */ bic r3, r3, #SDRAM_TUNE_EN /* Disable auto calibration */ bic r3, r3, #SDRAM_DRVN_MASK /* Clear r1[5:0] */ bic r3, r3, #SDRAM_DRVP_MASK /* Clear r1[11:6] */ /* Get the final N locked value of driving strength [22:17] */ mov r1, r3 mov r1, r1, LSL #9 mov r1, r1, LSR #26 orr r1, r1, r1, LSL #6 /* r1[5:0] = r3[22:17] */ /* Write to both bits [5:0] and bits [11:6] */ orr r3, r3, r1 MV_REG_WRITE_ASM (r3, r1, SDRAM_DATA_PADS_CAL_REG) glMem2End: /* Implement Guideline (GL# MEM-3) Drive Strength Value */ /* Relevant for: 88F5181-A1/B0/B1, 88F5281-A0/B0/C/D, 88F5182, */ /* 88F5082, 88F5181L, 88F6082/L, 88F6183, 88F6183L */ /* Get SDRAM Config value */ MV_REG_READ_ASM (r2, r1, SDRAM_CONFIG_REG) /* Get DIMM type */ tst r2, #SDRAM_DTYPE_DDR2 beq ddr1StrengthVal ddr2StrengthVal: ldr r4, =DDR2_ADDR_CTRL_PAD_STRENGTH_TYPICAL_DV ldr r2, =DDR2_DATA_PAD_STRENGTH_TYPICAL_DV b setDrvStrength ddr1StrengthVal: ldr r4, =DDR1_ADDR_CTRL_PAD_STRENGTH_TYPICAL_DV ldr r2, =DDR1_DATA_PAD_STRENGTH_TYPICAL_DV setDrvStrength: /* DDR SDRAM Address/Control Pads Calibration */ MV_REG_READ_ASM (r3, r1, SDRAM_ADDR_CTRL_PADS_CAL_REG) orr r3, r3, #SDRAM_WR_EN /* Make register writeable */ MV_REG_WRITE_ASM (r3, r1, SDRAM_ADDR_CTRL_PADS_CAL_REG) HTOLL(r3,r1) bic r3, r3, #SDRAM_WR_EN /* Make register read-only */ bic r3, r3, #SDRAM_PRE_DRIVER_STRENGTH_MASK orr r3, r4, r3 /* Set default value for DDR */ MV_REG_WRITE_ASM (r3, r1, SDRAM_ADDR_CTRL_PADS_CAL_REG) /* DDR SDRAM Data Pads Calibration */ MV_REG_READ_ASM (r3, r1, SDRAM_DATA_PADS_CAL_REG) orr r3, r3, #SDRAM_WR_EN /* Make register writeable */ MV_REG_WRITE_ASM (r3, r1, SDRAM_DATA_PADS_CAL_REG) HTOLL(r3,r1) bic r3, r3, #SDRAM_WR_EN /* Make register read-only */ bic r3, r3, #SDRAM_PRE_DRIVER_STRENGTH_MASK orr r3, r2, r3 /* Set default value for DDR */ MV_REG_WRITE_ASM (r3, r1, SDRAM_DATA_PADS_CAL_REG) #if !defined(MV_88W8660) && !defined(MV_88F6183) && !defined(MV_88F6183L) /* Implement Guideline (GL# MEM-4) DQS Reference Delay Tuning */ /* Relevant for: 88F5181-A1/B0/B1 and 88F5281-A0/B0/C/D, 88F5182 */ /* 88F5082, 88F5181L, 88F6082/L */ /* Calc the absolute address of the _cpuARMDDRCLK[] in the boot flash */ ldr r7, = _cpuARMDDRCLK ldr r4, =_start sub r7, r7, r4 add r7, r7, #CFG_MONITOR_BASE /* Get the "sample on reset" register for the DDR frequancy */ MV_REG_READ_ASM (r4, r1, MPP_SAMPLE_AT_RESET) ldr r1, =MSAR_ARMDDRCLCK_MASK and r1, r4, r1 #if 0 /* YOTAM TO BE FIX */ mov r1, r1, LSR #MSAR_ARMDDRCLCK_OFFS #endif /* Read device ID */ MV_CTRL_MODEL_GET_ASM(r3, r2); /* Continue if TC90 */ ldr r2, =MV_1281_DEV_ID cmp r3, r2 beq armClkMsb /* Continue if Orion2 */ ldr r2, =MV_5281_DEV_ID cmp r3, r2 #if 0 /* YOTAM TO BE FIX */ bne 1f #endif armClkMsb: #if 0 /* YOTAM TO BE FIX */ tst r4, #MSAR_ARMDDRCLCK_H_MASK beq 1f orr r1, r1, #BIT4 1: ldr r4, =MV_CPU_ARM_CLK_ELM_SIZE mul r1, r4, r1 add r7, r7, r1 add r7, r7, #MV_CPU_ARM_CLK_DDR_OFF ldr r1, [r7] #endif /* Get SDRAM Config value */ MV_REG_READ_ASM (r2, r4, SDRAM_CONFIG_REG) /* Get DIMM type */ tst r2, #SDRAM_DTYPE_DDR2 beq ddr1FtdllVal ddr2FtdllVal: ldr r2, =MV_5281_DEV_ID cmp r3, r2 bne 2f MV_CTRL_REV_GET_ASM(r3, r2) cmp r3, #MV_5281_D0_REV beq orin2_d0_ddr2_ftdll_val cmp r3, #MV_5281_D1_REV beq orin2_d1_ddr2_ftdll_val cmp r3, #MV_5281_D2_REV beq orin2_d1_ddr2_ftdll_val b ddr2_default_val /* Set Orion 2 D1 ftdll values for DDR2 */ orin2_d1_ddr2_ftdll_val: ldr r4, =FTDLL_DDR2_250MHZ_5281_D1 ldr r7, =_250MHz cmp r1, r7 beq setFtdllReg ldr r4, =FTDLL_DDR2_200MHZ_5281_D1 ldr r7, =_200MHz cmp r1, r7 beq setFtdllReg ldr r4, =FTDLL_DDR2_166MHZ_5281_D0 ldr r7, =_166MHz cmp r1, r7 beq setFtdllReg b ddr2_default_val /* Set Orion 2 D0 ftdll values for DDR2 */ orin2_d0_ddr2_ftdll_val: ldr r4, =FTDLL_DDR2_250MHZ_5281_D0 ldr r7, =_250MHz cmp r1, r7 beq setFtdllReg ldr r4, =FTDLL_DDR2_200MHZ_5281_D0 ldr r7, =_200MHz cmp r1, r7 beq setFtdllReg ldr r4, =FTDLL_DDR2_166MHZ_5281_D0 ldr r7, =_166MHz cmp r1, r7 beq setFtdllReg b ddr2_default_val 2: ldr r2, =MV_5182_DEV_ID cmp r3, r2 bne 3f /* Set Orion nas ftdll values for DDR2 */ orin_nas_ftdll_val: ldr r4, =FTDLL_DDR2_166MHZ_5182 ldr r7, =_166MHz cmp r1, r7 beq setFtdllReg /* default values for all other devices */ 3: ddr2_default_val: ldr r4, =FTDLL_DDR2_250MHZ ldr r7, =_250MHz cmp r1, r7 beq setFtdllReg ldr r4, =FTDLL_DDR2_200MHZ ldr r7, =_200MHz cmp r1, r7 beq setFtdllReg ldr r4, =FTDLL_DDR2_166MHZ ldr r7, =_166MHz cmp r1, r7 beq setFtdllReg ldr r4, =FTDLL_DDR2_133MHZ ldr r7, =_133MHz cmp r1, r7 beq setFtdllReg ldr r4, =0 b setFtdllReg ddr1FtdllVal: ldr r2, =MV_5281_DEV_ID cmp r3, r2 bne 2f MV_CTRL_REV_GET_ASM(r3, r2) cmp r3, #MV_5281_D0_REV bge orin2_ddr1_ftdll_val b ddr1_default_val /* Set Orion 2 D0 and above ftdll values for DDR1 */ orin2_ddr1_ftdll_val: ldr r4, =FTDLL_DDR1_200MHZ_5281_D0 ldr r7, =_200MHz cmp r1, r7 beq setFtdllReg ldr r4, =FTDLL_DDR1_166MHZ_5281_D0 ldr r7, =_166MHz cmp r1, r7 beq setFtdllReg b ddr1_default_val 2: ldr r2, =MV_5181_DEV_ID cmp r3, r2 bne 3f MV_CTRL_REV_GET_ASM(r3, r2) cmp r3, #MV_5181_B1_REV bge orin1_ddr1_ftdll_val b ddr1_default_val /* Set Orion 1 ftdll values for DDR1 */ orin1_ddr1_ftdll_val: ldr r4, =FTDLL_DDR1_166MHZ_5181_B1 ldr r7, =_166MHz cmp r1, r7 beq setFtdllReg 3: ddr1_default_val: ldr r4, =FTDLL_DDR1_133MHZ ldr r7, =_133MHz cmp r1, r7 beq setFtdllReg ldr r4, =FTDLL_DDR1_166MHZ ldr r7, =_166MHz cmp r1, r7 beq setFtdllReg ldr r4, =FTDLL_DDR1_200MHZ ldr r7, =_200MHz cmp r1, r7 beq setFtdllReg ldr r4, =0 setFtdllReg: MV_REG_WRITE_ASM (r4, r1, SDRAM_FTDLL_CONFIG_REG) HTOLL(r4,r1) bic r4, r4, #1 MV_REG_WRITE_ASM (r4, r1, SDRAM_FTDLL_CONFIG_REG) #endif /* !defined(MV_88W8660) && !defined(MV_88F6183) && !defined(MV_88F6183L) */ #endif /* DB_FPGA */ restoreTmpRegs: /* Restore the registers we used to save the DDR detect values */ ldr r4, =DRAM_BUF_REG0_DV MV_REG_WRITE_ASM (r4, r1, DRAM_BUF_REG0) ldr r4, =DRAM_BUF_REG1_DV MV_REG_WRITE_ASM (r4, r1, DRAM_BUF_REG1) ldr r4, =DRAM_BUF_REG2_DV MV_REG_WRITE_ASM (r4, r1, DRAM_BUF_REG2) ldr r4, =DRAM_BUF_REG3_DV MV_REG_WRITE_ASM (r4, r1, DRAM_BUF_REG3) ldr r4, =DRAM_BUF_REG4_DV MV_REG_WRITE_ASM (r4, r1, DRAM_BUF_REG4) ldr r4, =DRAM_BUF_REG5_DV MV_REG_WRITE_ASM (r4, r1, DRAM_BUF_REG5) ldr r4, =DRAM_BUF_REG6_DV MV_REG_WRITE_ASM (r4, r1, DRAM_BUF_REG6) ldr r4, =DRAM_BUF_REG7_DV MV_REG_WRITE_ASM (r4, r1, DRAM_BUF_REG7) ldr r4, =DRAM_BUF_REG8_DV MV_REG_WRITE_ASM (r4, r1, DRAM_BUF_REG8) ldr r4, =DRAM_BUF_REG9_DV MV_REG_WRITE_ASM (r4, r1, DRAM_BUF_REG9) ldr r4, =DRAM_BUF_REG10_DV MV_REG_WRITE_ASM (r4, r1, DRAM_BUF_REG10) /* Restore registers */ /* Save register on stack */ cmp sp, #0 beq no_stack_l load_from_stack: ldmia sp!, {r1, r2, r3, r4, r7, r11} no_stack_l: mov pc, lr