[PATCH 07/24] ARM: at91: pm: avoid push and pop on stack while memory is in self-refersh

From: Claudiu Beznea
Date: Wed Mar 31 2021 - 07:00:39 EST

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For the previous AT91 RAM controller and self-refresh procedure this
had no side effects. However, for SAMA7G5 the self-refresh procedure
doesn't allow this anymore as the RAM controller ports are closed
before switching it to self-refresh. This commits prepares the code
for the following ones adding self-refresh and PM support for SAMA7G5.

Signed-off-by: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx>
---
arch/arm/mach-at91/pm_suspend.S | 397 +++++++++++++++++---------------
1 file changed, 205 insertions(+), 192 deletions(-)

diff --git a/arch/arm/mach-at91/pm_suspend.S b/arch/arm/mach-at91/pm_suspend.S
index 3d20c9880fee..960ad29cce51 100644
--- a/arch/arm/mach-at91/pm_suspend.S
+++ b/arch/arm/mach-at91/pm_suspend.S
@@ -75,98 +75,147 @@ tmp3 .req r6

.arm

-/*
- * void at91_suspend_sram_fn(struct at91_pm_data*)
- * @input param:
- * @r0: base address of struct at91_pm_data
+/**
+ * Enable self-refresh
+ *
+ * register usage:
+ * @r1: memory type
+ * @r2: base address of the sram controller
+ * @r3: temporary
*/
-/* at91_pm_suspend_in_sram must be 8-byte aligned per the requirements of fncpy() */
- .align 3
-ENTRY(at91_pm_suspend_in_sram)
- /* Save registers on stack */
- stmfd sp!, {r4 - r12, lr}
+.macro at91_sramc_self_refresh_ena
+ ldr r1, .memtype
+ ldr r2, .sramc_base

- /* Drain write buffer */
- mov tmp1, #0
- mcr p15, 0, tmp1, c7, c10, 4
+ cmp r1, #AT91_MEMCTRL_MC
+ bne sr_ena_ddrc_sf

- ldr tmp1, [r0, #PM_DATA_PMC]
- str tmp1, .pmc_base
- ldr tmp1, [r0, #PM_DATA_RAMC0]
- str tmp1, .sramc_base
- ldr tmp1, [r0, #PM_DATA_RAMC1]
- str tmp1, .sramc1_base
- ldr tmp1, [r0, #PM_DATA_MEMCTRL]
- str tmp1, .memtype
- ldr tmp1, [r0, #PM_DATA_MODE]
- str tmp1, .pm_mode
- ldr tmp1, [r0, #PM_DATA_PMC_MCKR_OFFSET]
- str tmp1, .mckr_offset
- ldr tmp1, [r0, #PM_DATA_PMC_VERSION]
- str tmp1, .pmc_version
- /* Both ldrne below are here to preload their address in the TLB */
- ldr tmp1, [r0, #PM_DATA_SHDWC]
- str tmp1, .shdwc
- cmp tmp1, #0
- ldrne tmp2, [tmp1, #0]
- ldr tmp1, [r0, #PM_DATA_SFRBU]
- str tmp1, .sfrbu
- cmp tmp1, #0
- ldrne tmp2, [tmp1, #0x10]
+ /* Active SDRAM self-refresh mode */
+ mov r3, #1
+ str r3, [r2, #AT91_MC_SDRAMC_SRR]
+ b sr_ena_exit

- /* Active the self-refresh mode */
- mov r0, #SRAMC_SELF_FRESH_ACTIVE
- bl at91_sramc_self_refresh
+sr_ena_ddrc_sf:
+ cmp r1, #AT91_MEMCTRL_DDRSDR
+ bne sr_ena_sdramc_sf

- ldr r0, .pm_mode
- cmp r0, #AT91_PM_STANDBY
- beq standby
- cmp r0, #AT91_PM_BACKUP
- beq backup_mode
+ /*
+ * DDR Memory controller
+ */

- bl at91_ulp_mode
- b exit_suspend
+ /* LPDDR1 --> force DDR2 mode during self-refresh */
+ ldr r3, [r2, #AT91_DDRSDRC_MDR]
+ str r3, .saved_sam9_mdr
+ bic r3, r3, #~AT91_DDRSDRC_MD
+ cmp r3, #AT91_DDRSDRC_MD_LOW_POWER_DDR
+ ldreq r3, [r2, #AT91_DDRSDRC_MDR]
+ biceq r3, r3, #AT91_DDRSDRC_MD
+ orreq r3, r3, #AT91_DDRSDRC_MD_DDR2
+ streq r3, [r2, #AT91_DDRSDRC_MDR]

-standby:
- /* Wait for interrupt */
- ldr pmc, .pmc_base
- at91_cpu_idle
- b exit_suspend
+ /* Active DDRC self-refresh mode */
+ ldr r3, [r2, #AT91_DDRSDRC_LPR]
+ str r3, .saved_sam9_lpr
+ bic r3, r3, #AT91_DDRSDRC_LPCB
+ orr r3, r3, #AT91_DDRSDRC_LPCB_SELF_REFRESH
+ str r3, [r2, #AT91_DDRSDRC_LPR]

-backup_mode:
- bl at91_backup_mode
- b exit_suspend
+ /* If using the 2nd ddr controller */
+ ldr r2, .sramc1_base
+ cmp r2, #0
+ beq sr_ena_no_2nd_ddrc

-exit_suspend:
- /* Exit the self-refresh mode */
- mov r0, #SRAMC_SELF_FRESH_EXIT
- bl at91_sramc_self_refresh
+ ldr r3, [r2, #AT91_DDRSDRC_MDR]
+ str r3, .saved_sam9_mdr1
+ bic r3, r3, #~AT91_DDRSDRC_MD
+ cmp r3, #AT91_DDRSDRC_MD_LOW_POWER_DDR
+ ldreq r3, [r2, #AT91_DDRSDRC_MDR]
+ biceq r3, r3, #AT91_DDRSDRC_MD
+ orreq r3, r3, #AT91_DDRSDRC_MD_DDR2
+ streq r3, [r2, #AT91_DDRSDRC_MDR]

- /* Restore registers, and return */
- ldmfd sp!, {r4 - r12, pc}
-ENDPROC(at91_pm_suspend_in_sram)
+ /* Active DDRC self-refresh mode */
+ ldr r3, [r2, #AT91_DDRSDRC_LPR]
+ str r3, .saved_sam9_lpr1
+ bic r3, r3, #AT91_DDRSDRC_LPCB
+ orr r3, r3, #AT91_DDRSDRC_LPCB_SELF_REFRESH
+ str r3, [r2, #AT91_DDRSDRC_LPR]

-ENTRY(at91_backup_mode)
- /* Switch the master clock source to slow clock. */
- ldr pmc, .pmc_base
- ldr tmp2, .mckr_offset
- ldr tmp1, [pmc, tmp2]
- bic tmp1, tmp1, #AT91_PMC_CSS
- str tmp1, [pmc, tmp2]
+sr_ena_no_2nd_ddrc:
+ b sr_ena_exit

- wait_mckrdy
+ /*
+ * SDRAMC Memory controller
+ */
+sr_ena_sdramc_sf:
+ /* Active SDRAMC self-refresh mode */
+ ldr r3, [r2, #AT91_SDRAMC_LPR]
+ str r3, .saved_sam9_lpr
+ bic r3, r3, #AT91_SDRAMC_LPCB
+ orr r3, r3, #AT91_SDRAMC_LPCB_SELF_REFRESH
+ str r3, [r2, #AT91_SDRAMC_LPR]

- /*BUMEN*/
- ldr r0, .sfrbu
- mov tmp1, #0x1
- str tmp1, [r0, #0x10]
+ ldr r3, .saved_sam9_lpr
+ str r3, [r2, #AT91_SDRAMC_LPR]

- /* Shutdown */
- ldr r0, .shdwc
- mov tmp1, #0xA5000000
- add tmp1, tmp1, #0x1
- str tmp1, [r0, #0]
-ENDPROC(at91_backup_mode)
+sr_ena_exit:
+.endm
+
+/**
+ * Disable self-refresh
+ *
+ * register usage:
+ * @r1: memory type
+ * @r2: base address of the sram controller
+ * @r3: temporary
+ */
+.macro at91_sramc_self_refresh_dis
+ ldr r1, .memtype
+ ldr r2, .sramc_base
+
+ cmp r1, #AT91_MEMCTRL_MC
+ bne sr_dis_ddrc_exit_sf
+
+ /*
+ * at91rm9200 Memory controller
+ */
+
+ /*
+ * For exiting the self-refresh mode, do nothing,
+ * automatically exit the self-refresh mode.
+ */
+ b sr_dis_exit
+
+sr_dis_ddrc_exit_sf:
+ cmp r1, #AT91_MEMCTRL_DDRSDR
+ bne sdramc_exit_sf
+
+ /* DDR Memory controller */
+
+ /* Restore MDR in case of LPDDR1 */
+ ldr r3, .saved_sam9_mdr
+ str r3, [r2, #AT91_DDRSDRC_MDR]
+ /* Restore LPR on AT91 with DDRAM */
+ ldr r3, .saved_sam9_lpr
+ str r3, [r2, #AT91_DDRSDRC_LPR]
+
+ /* If using the 2nd ddr controller */
+ ldr r2, .sramc1_base
+ cmp r2, #0
+ ldrne r3, .saved_sam9_mdr1
+ strne r3, [r2, #AT91_DDRSDRC_MDR]
+ ldrne r3, .saved_sam9_lpr1
+ strne r3, [r2, #AT91_DDRSDRC_LPR]
+
+ b sr_dis_exit
+
+sdramc_exit_sf:
+ /* SDRAMC Memory controller */
+ ldr r3, .saved_sam9_lpr
+ str r3, [r2, #AT91_SDRAMC_LPR]
+
+sr_dis_exit:
+.endm

.macro at91_pm_ulp0_mode
ldr pmc, .pmc_base
@@ -503,7 +552,7 @@ ENDPROC(at91_backup_mode)
2:
.endm

-ENTRY(at91_ulp_mode)
+.macro at91_ulp_mode
ldr pmc, .pmc_base
ldr tmp2, .mckr_offset
ldr tmp3, .pm_mode
@@ -552,133 +601,97 @@ ulp_exit:

wait_mckrdy

- mov pc, lr
-ENDPROC(at91_ulp_mode)
-
-/*
- * void at91_sramc_self_refresh(unsigned int is_active)
- *
- * @input param:
- * @r0: 1 - active self-refresh mode
- * 0 - exit self-refresh mode
- * register usage:
- * @r1: memory type
- * @r2: base address of the sram controller
- */
-
-ENTRY(at91_sramc_self_refresh)
- ldr r1, .memtype
- ldr r2, .sramc_base
-
- cmp r1, #AT91_MEMCTRL_MC
- bne ddrc_sf
-
- /*
- * at91rm9200 Memory controller
- */
-
- /*
- * For exiting the self-refresh mode, do nothing,
- * automatically exit the self-refresh mode.
- */
- tst r0, #SRAMC_SELF_FRESH_ACTIVE
- beq exit_sramc_sf
-
- /* Active SDRAM self-refresh mode */
- mov r3, #1
- str r3, [r2, #AT91_MC_SDRAMC_SRR]
- b exit_sramc_sf
-
-ddrc_sf:
- cmp r1, #AT91_MEMCTRL_DDRSDR
- bne sdramc_sf
+.endm

- /*
- * DDR Memory controller
- */
- tst r0, #SRAMC_SELF_FRESH_ACTIVE
- beq ddrc_exit_sf
+.macro at91_backup_mode
+ /* Switch the master clock source to slow clock. */
+ ldr pmc, .pmc_base
+ ldr tmp2, .mckr_offset
+ ldr tmp1, [pmc, tmp2]
+ bic tmp1, tmp1, #AT91_PMC_CSS
+ str tmp1, [pmc, tmp2]

- /* LPDDR1 --> force DDR2 mode during self-refresh */
- ldr r3, [r2, #AT91_DDRSDRC_MDR]
- str r3, .saved_sam9_mdr
- bic r3, r3, #~AT91_DDRSDRC_MD
- cmp r3, #AT91_DDRSDRC_MD_LOW_POWER_DDR
- ldreq r3, [r2, #AT91_DDRSDRC_MDR]
- biceq r3, r3, #AT91_DDRSDRC_MD
- orreq r3, r3, #AT91_DDRSDRC_MD_DDR2
- streq r3, [r2, #AT91_DDRSDRC_MDR]
+ wait_mckrdy

- /* Active DDRC self-refresh mode */
- ldr r3, [r2, #AT91_DDRSDRC_LPR]
- str r3, .saved_sam9_lpr
- bic r3, r3, #AT91_DDRSDRC_LPCB
- orr r3, r3, #AT91_DDRSDRC_LPCB_SELF_REFRESH
- str r3, [r2, #AT91_DDRSDRC_LPR]
+ /*BUMEN*/
+ ldr r0, .sfrbu
+ mov tmp1, #0x1
+ str tmp1, [r0, #0x10]

- /* If using the 2nd ddr controller */
- ldr r2, .sramc1_base
- cmp r2, #0
- beq no_2nd_ddrc
+ /* Shutdown */
+ ldr r0, .shdwc
+ mov tmp1, #0xA5000000
+ add tmp1, tmp1, #0x1
+ str tmp1, [r0, #0]
+.endm

- ldr r3, [r2, #AT91_DDRSDRC_MDR]
- str r3, .saved_sam9_mdr1
- bic r3, r3, #~AT91_DDRSDRC_MD
- cmp r3, #AT91_DDRSDRC_MD_LOW_POWER_DDR
- ldreq r3, [r2, #AT91_DDRSDRC_MDR]
- biceq r3, r3, #AT91_DDRSDRC_MD
- orreq r3, r3, #AT91_DDRSDRC_MD_DDR2
- streq r3, [r2, #AT91_DDRSDRC_MDR]
+/*
+ * void at91_suspend_sram_fn(struct at91_pm_data*)
+ * @input param:
+ * @r0: base address of struct at91_pm_data
+ */
+/* at91_pm_suspend_in_sram must be 8-byte aligned per the requirements of fncpy() */
+ .align 3
+ENTRY(at91_pm_suspend_in_sram)
+ /* Save registers on stack */
+ stmfd sp!, {r4 - r12, lr}

- /* Active DDRC self-refresh mode */
- ldr r3, [r2, #AT91_DDRSDRC_LPR]
- str r3, .saved_sam9_lpr1
- bic r3, r3, #AT91_DDRSDRC_LPCB
- orr r3, r3, #AT91_DDRSDRC_LPCB_SELF_REFRESH
- str r3, [r2, #AT91_DDRSDRC_LPR]
+ /* Drain write buffer */
+ mov tmp1, #0
+ mcr p15, 0, tmp1, c7, c10, 4

-no_2nd_ddrc:
- b exit_sramc_sf
+ ldr tmp1, [r0, #PM_DATA_PMC]
+ str tmp1, .pmc_base
+ ldr tmp1, [r0, #PM_DATA_RAMC0]
+ str tmp1, .sramc_base
+ ldr tmp1, [r0, #PM_DATA_RAMC1]
+ str tmp1, .sramc1_base
+ ldr tmp1, [r0, #PM_DATA_MEMCTRL]
+ str tmp1, .memtype
+ ldr tmp1, [r0, #PM_DATA_MODE]
+ str tmp1, .pm_mode
+ ldr tmp1, [r0, #PM_DATA_PMC_MCKR_OFFSET]
+ str tmp1, .mckr_offset
+ ldr tmp1, [r0, #PM_DATA_PMC_VERSION]
+ str tmp1, .pmc_version
+ /* Both ldrne below are here to preload their address in the TLB */
+ ldr tmp1, [r0, #PM_DATA_SHDWC]
+ str tmp1, .shdwc
+ cmp tmp1, #0
+ ldrne tmp2, [tmp1, #0]
+ ldr tmp1, [r0, #PM_DATA_SFRBU]
+ str tmp1, .sfrbu
+ cmp tmp1, #0
+ ldrne tmp2, [tmp1, #0x10]

-ddrc_exit_sf:
- /* Restore MDR in case of LPDDR1 */
- ldr r3, .saved_sam9_mdr
- str r3, [r2, #AT91_DDRSDRC_MDR]
- /* Restore LPR on AT91 with DDRAM */
- ldr r3, .saved_sam9_lpr
- str r3, [r2, #AT91_DDRSDRC_LPR]
+ /* Active the self-refresh mode */
+ at91_sramc_self_refresh_ena

- /* If using the 2nd ddr controller */
- ldr r2, .sramc1_base
- cmp r2, #0
- ldrne r3, .saved_sam9_mdr1
- strne r3, [r2, #AT91_DDRSDRC_MDR]
- ldrne r3, .saved_sam9_lpr1
- strne r3, [r2, #AT91_DDRSDRC_LPR]
+ ldr r0, .pm_mode
+ cmp r0, #AT91_PM_STANDBY
+ beq standby
+ cmp r0, #AT91_PM_BACKUP
+ beq backup_mode

- b exit_sramc_sf
+ at91_ulp_mode
+ b exit_suspend

- /*
- * SDRAMC Memory controller
- */
-sdramc_sf:
- tst r0, #SRAMC_SELF_FRESH_ACTIVE
- beq sdramc_exit_sf
+standby:
+ /* Wait for interrupt */
+ ldr pmc, .pmc_base
+ at91_cpu_idle
+ b exit_suspend

- /* Active SDRAMC self-refresh mode */
- ldr r3, [r2, #AT91_SDRAMC_LPR]
- str r3, .saved_sam9_lpr
- bic r3, r3, #AT91_SDRAMC_LPCB
- orr r3, r3, #AT91_SDRAMC_LPCB_SELF_REFRESH
- str r3, [r2, #AT91_SDRAMC_LPR]
+backup_mode:
+ at91_backup_mode

-sdramc_exit_sf:
- ldr r3, .saved_sam9_lpr
- str r3, [r2, #AT91_SDRAMC_LPR]
+exit_suspend:
+ /* Exit the self-refresh mode */
+ at91_sramc_self_refresh_dis

-exit_sramc_sf:
- mov pc, lr
-ENDPROC(at91_sramc_self_refresh)
+ /* Restore registers, and return */
+ ldmfd sp!, {r4 - r12, pc}
+ENDPROC(at91_pm_suspend_in_sram)

.pmc_base:
.word 0
--
2.25.1

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Previous message: Claudiu Beznea: "[PATCH 06/24] ARM: at91: pm: use r7 instead of tmp1"
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Next in thread: Claudiu Beznea: "[PATCH 08/24] ARM: at91: pm: s/CONFIG_SOC_SAM9X60/CONFIG_HAVE_AT91_SAM9X60_PLL/g"
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