avr32: Power Management support ("standby" and "mem" modes)
Implement Standby support. In this mode, we'll suspend all drivers,
put the SDRAM in self-refresh mode and switch off the HSB bus
("frozen" mode.)
Implement Suspend-to-mem support. In this mode, we suspend all
drivers, put the SDRAM into self-refresh mode and switch off all
internal clocks except the 32 kHz oscillator ("stop" mode.)
The lowest-level suspend code runs from a small portion of SRAM
allocated at startup time. This gets rid of a small potential race
with the SDRAM where we might try to enter self-refresh mode in the
middle of an icache burst. We also relocate all interrupt and
exception handlers to SRAM during the small window when we enter and
exit the low-power modes.
We don't need to do any special tricks to start and stop the PLL. The
main clock is automatically gated by hardware until the PLL is stable.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
diff --git a/arch/avr32/mach-at32ap/pm-at32ap700x.S b/arch/avr32/mach-at32ap/pm-at32ap700x.S
index 949e248..0a53ad3 100644
--- a/arch/avr32/mach-at32ap/pm-at32ap700x.S
+++ b/arch/avr32/mach-at32ap/pm-at32ap700x.S
@@ -12,6 +12,12 @@
#include <asm/thread_info.h>
#include <asm/arch/pm.h>
+#include "pm.h"
+#include "sdramc.h"
+
+/* Same as 0xfff00000 but fits in a 21 bit signed immediate */
+#define PM_BASE -0x100000
+
.section .bss, "wa", @nobits
.global disable_idle_sleep
.type disable_idle_sleep, @object
@@ -64,3 +70,105 @@
unmask_interrupts
retal r12
.size cpu_idle_skip_sleep, . - cpu_idle_skip_sleep
+
+#ifdef CONFIG_PM
+ .section .init.text, "ax", @progbits
+
+ .global pm_exception
+ .type pm_exception, @function
+pm_exception:
+ /*
+ * Exceptions are masked when we switch to this handler, so
+ * we'll only get "unrecoverable" exceptions (offset 0.)
+ */
+ sub r12, pc, . - .Lpanic_msg
+ lddpc pc, .Lpanic_addr
+
+ .align 2
+.Lpanic_addr:
+ .long panic
+.Lpanic_msg:
+ .asciz "Unrecoverable exception during suspend\n"
+ .size pm_exception, . - pm_exception
+
+ .global pm_irq0
+ .type pm_irq0, @function
+pm_irq0:
+ /* Disable interrupts and return after the sleep instruction */
+ mfsr r9, SYSREG_RSR_INT0
+ mtsr SYSREG_RAR_INT0, r8
+ sbr r9, SYSREG_GM_OFFSET
+ mtsr SYSREG_RSR_INT0, r9
+ rete
+
+ /*
+ * void cpu_enter_standby(unsigned long sdramc_base)
+ *
+ * Enter PM_SUSPEND_STANDBY mode. At this point, all drivers
+ * are suspended and interrupts are disabled. Interrupts
+ * marked as 'wakeup' event sources may still come along and
+ * get us out of here.
+ *
+ * The SDRAM will be put into self-refresh mode (which does
+ * not require a clock from the CPU), and the CPU will be put
+ * into "frozen" mode (HSB bus stopped). The SDRAM controller
+ * will automatically bring the SDRAM into normal mode on the
+ * first access, and the power manager will automatically
+ * start the HSB and CPU clocks upon a wakeup event.
+ *
+ * This code uses the same "skip sleep" technique as above.
+ * It is very important that we jump directly to
+ * cpu_after_sleep after the sleep instruction since that's
+ * where we'll end up if the interrupt handler decides that we
+ * need to skip the sleep instruction.
+ */
+ .global pm_standby
+ .type pm_standby, @function
+pm_standby:
+ /*
+ * interrupts are already masked at this point, and EVBA
+ * points to pm_exception above.
+ */
+ ld.w r10, r12[SDRAMC_LPR]
+ sub r8, pc, . - 1f /* return address for irq handler */
+ mov r11, SDRAMC_LPR_LPCB_SELF_RFR
+ bfins r10, r11, 0, 2 /* LPCB <- self Refresh */
+ sync 0 /* flush write buffer */
+ st.w r12[SDRAMC_LPR], r11 /* put SDRAM in self-refresh mode */
+ ld.w r11, r12[SDRAMC_LPR]
+ unmask_interrupts
+ sleep CPU_SLEEP_FROZEN
+1: mask_interrupts
+ retal r12
+ .size pm_standby, . - pm_standby
+
+ .global pm_suspend_to_ram
+ .type pm_suspend_to_ram, @function
+pm_suspend_to_ram:
+ /*
+ * interrupts are already masked at this point, and EVBA
+ * points to pm_exception above.
+ */
+ mov r11, 0
+ cache r11[2], 8 /* clean all dcache lines */
+ sync 0 /* flush write buffer */
+ ld.w r10, r12[SDRAMC_LPR]
+ sub r8, pc, . - 1f /* return address for irq handler */
+ mov r11, SDRAMC_LPR_LPCB_SELF_RFR
+ bfins r10, r11, 0, 2 /* LPCB <- self refresh */
+ st.w r12[SDRAMC_LPR], r10 /* put SDRAM in self-refresh mode */
+ ld.w r11, r12[SDRAMC_LPR]
+
+ unmask_interrupts
+ sleep CPU_SLEEP_STOP
+1: mask_interrupts
+
+ retal r12
+ .size pm_suspend_to_ram, . - pm_suspend_to_ram
+
+ .global pm_sram_end
+ .type pm_sram_end, @function
+pm_sram_end:
+ .size pm_sram_end, 0
+
+#endif /* CONFIG_PM */