powerpc/powernv/idle: add a basic stop 0-3 driver for POWER10

This driver does not restore stop > 3 state, so it limits itself
to states which do not lose full state or TB.

The POWER10 SPRs are sufficiently different from P9 that it seems
easier to split out the P10 code. The POWER10 deep sleep code
(e.g., the BHRB restore) has been taken out, but it can be re-added
when stop > 3 support is added.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Tested-by: Pratik Rajesh Sampat<psampat@linux.ibm.com>
Tested-by: Vaidyanathan Srinivasan <svaidy@linux.ibm.com>
Reviewed-by: Pratik Rajesh Sampat<psampat@linux.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200819094700.493399-1-npiggin@gmail.com

arch/powerpc/include/asm/machdep.h

@@ -222,8 +222,6 @@ struct machdep_calls {
 
 extern void e500_idle(void);
 extern void power4_idle(void);
-extern void power7_idle(void);
-extern void power9_idle(void);
 extern void ppc6xx_idle(void);
 extern void book3e_idle(void);
 

arch/powerpc/include/asm/processor.h

@@ -432,7 +432,7 @@ enum idle_boot_override {IDLE_NO_OVERRIDE = 0, IDLE_POWERSAVE_OFF};
 extern int powersave_nap;	/* set if nap mode can be used in idle loop */
 
 extern void power7_idle_type(unsigned long type);
-extern void power9_idle_type(unsigned long stop_psscr_val,
+extern void arch300_idle_type(unsigned long stop_psscr_val,
 			      unsigned long stop_psscr_mask);
 
 extern int fix_alignment(struct pt_regs *);

arch/powerpc/include/asm/reg.h

@@ -1353,6 +1353,7 @@
 #define PVR_POWER8NVL	0x004C
 #define PVR_POWER8	0x004D
 #define PVR_POWER9	0x004E
+#define PVR_POWER10	0x0080
 #define PVR_BE		0x0070
 #define PVR_PA6T	0x0090