MIPS: pm-cps: add PM state entry code for CPS systems

This patch adds code to generate entry & exit code for various low power
states available on systems based around the MIPS Coherent Processing
System architecture (ie. those with a Coherence Manager, Global
Interrupt Controller & for >=CM2 a Cluster Power Controller). States
supported are:

  - Non-coherent wait. This state first leaves the coherent domain and
    then executes a regular MIPS wait instruction. Power savings are
    found from the elimination of coherency interventions between the
    core and any other coherent requestors in the system.

  - Clock gated. This state leaves the coherent domain and then gates
    the clock input to the core. This removes all dynamic power from the
    core but leaves the core at the mercy of another to restart its
    clock. Register state is preserved, but the core can not service
    interrupts whilst its clock is gated.

  - Power gated. This deepest state removes all power input to the core.
    All register state is lost and the core will restart execution from
    its BEV when another core powers it back up. Because register state
    is lost this state requires cooperation with the CONFIG_MIPS_CPS SMP
    implementation in order for the core to exit the state successfully.

The code will detect which states are available on the current system
during boot & generate the entry/exit code for those states. This will
be used by cpuidle & hotplug implementations.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/arch/mips/kernel/cps-vec.S b/arch/mips/kernel/cps-vec.S
index 57ec18c7d17f..1c865ae922a5 100644
--- a/arch/mips/kernel/cps-vec.S
+++ b/arch/mips/kernel/cps-vec.S
@@ -15,6 +15,7 @@
 #include <asm/cacheops.h>
 #include <asm/mipsregs.h>
 #include <asm/mipsmtregs.h>
+#include <asm/pm.h>
 
 #define GCR_CL_COHERENCE_OFS	0x2008
 #define GCR_CL_ID_OFS		0x2028
@@ -447,3 +448,37 @@ LEAF(mips_cps_boot_vpes)
 	jr	ra
 	 nop
 	END(mips_cps_boot_vpes)
+
+#if defined(CONFIG_MIPS_CPS_PM) && defined(CONFIG_CPU_PM)
+
+	/* Calculate a pointer to this CPUs struct mips_static_suspend_state */
+	.macro	psstate	dest
+	.set	push
+	.set	noat
+	lw	$1, TI_CPU(gp)
+	sll	$1, $1, LONGLOG
+	la	\dest, __per_cpu_offset
+	addu	$1, $1, \dest
+	lw	$1, 0($1)
+	la	\dest, cps_cpu_state
+	addu	\dest, \dest, $1
+	.set	pop
+	.endm
+
+LEAF(mips_cps_pm_save)
+	/* Save CPU state */
+	SUSPEND_SAVE_REGS
+	psstate	t1
+	SUSPEND_SAVE_STATIC
+	jr	v0
+	 nop
+	END(mips_cps_pm_save)
+
+LEAF(mips_cps_pm_restore)
+	/* Restore CPU state */
+	psstate	t1
+	RESUME_RESTORE_STATIC
+	RESUME_RESTORE_REGS_RETURN
+	END(mips_cps_pm_restore)
+
+#endif /* CONFIG_MIPS_CPS_PM && CONFIG_CPU_PM */