openrisc: initial SMP support

This patch introduces the SMP support for the OpenRISC architecture.
The SMP architecture requires cores which have multi-core features which
have been introduced a few years back including:

 - New SPRS SPR_COREID SPR_NUMCORES
 - Shadow SPRs
 - Atomic Instructions
 - Cache Coherency
 - A wired in IPI controller

This patch adds all of the SMP specific changes to core infrastructure,
it looks big but it needs to go all together as its hard to split this
one up.

Boot loader spinning of second cpu is not supported yet, it's assumed
that Linux is booted straight after cpu reset.

The bulk of these changes are trivial changes to refactor to use per cpu
data structures throughout.  The addition of the smp.c and changes in
time.c are the changes.  Some specific notes:

MM changes
----------
The reason why this is created as an array, and not with DEFINE_PER_CPU
is that doing it this way, we'll save a load in the tlb-miss handler
(the load from __per_cpu_offset).

TLB Flush
---------
The SMP implementation of flush_tlb_* works by sending out a
function-call IPI to all the non-local cpus by using the generic
on_each_cpu() function.

Currently, all flush_tlb_* functions will result in a flush_tlb_all(),
which has always been the behaviour in the UP case.

CPU INFO
--------
This creates a per cpu cpuinfo struct and fills it out accordingly for
each activated cpu.  show_cpuinfo is also updated to reflect new version
information in later versions of the spec.

SMP API
-------
This imitates the arm64 implementation by having a smp_cross_call
callback that can be set by set_smp_cross_call to initiate an IPI and a
handle_IPI function that is expected to be called from an IPI irqchip
driver.

Signed-off-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
[shorne@gmail.com: added cpu stop, checkpatch fixes, wrote commit message]
Signed-off-by: Stafford Horne <shorne@gmail.com>

8 files changed, 82 insertions, 11 deletions

diff --git a/arch/openrisc/include/asm/cpuinfo.h b/arch/openrisc/include/asm/cpuinfo.h
index ec10679d6429..4ea0a33eba6c 100644
--- a/arch/openrisc/include/asm/cpuinfo.h
+++ b/arch/openrisc/include/asm/cpuinfo.h
@@ -19,7 +19,7 @@
 #ifndef __ASM_OPENRISC_CPUINFO_H
 #define __ASM_OPENRISC_CPUINFO_H
 
-struct cpuinfo {
+struct cpuinfo_or1k {
 	u32 clock_frequency;
 
 	u32 icache_size;
@@ -29,8 +29,11 @@ struct cpuinfo {
 	u32 dcache_size;
 	u32 dcache_block_size;
 	u32 dcache_ways;
+
+	u16 coreid;
 };
 
-extern struct cpuinfo cpuinfo;
+extern struct cpuinfo_or1k cpuinfo_or1k[NR_CPUS];
+extern void setup_cpuinfo(void);
 
 #endif /* __ASM_OPENRISC_CPUINFO_H */
diff --git a/arch/openrisc/include/asm/mmu_context.h b/arch/openrisc/include/asm/mmu_context.h
index e94b814d2e3c..c380d8caf84f 100644
--- a/arch/openrisc/include/asm/mmu_context.h
+++ b/arch/openrisc/include/asm/mmu_context.h
@@ -34,7 +34,7 @@ extern void switch_mm(struct mm_struct *prev, struct mm_struct *next,
  * registers like cr3 on the i386
  */
 
-extern volatile pgd_t *current_pgd;   /* defined in arch/openrisc/mm/fault.c */
+extern volatile pgd_t *current_pgd[]; /* defined in arch/openrisc/mm/fault.c */
 
 static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
 {
diff --git a/arch/openrisc/include/asm/pgtable.h b/arch/openrisc/include/asm/pgtable.h
index 71a6f08de8f2..eff5ba2a5af2 100644
--- a/arch/openrisc/include/asm/pgtable.h
+++ b/arch/openrisc/include/asm/pgtable.h
@@ -94,7 +94,7 @@ extern void paging_init(void);
  * 64 MB of vmalloc area is comparable to what's available on other arches.
  */
 
-#define VMALLOC_START	(PAGE_OFFSET-0x04000000)
+#define VMALLOC_START	(PAGE_OFFSET-0x04000000UL)
 #define VMALLOC_END	(PAGE_OFFSET)
 #define VMALLOC_VMADDR(x) ((unsigned long)(x))
 
diff --git a/arch/openrisc/include/asm/serial.h b/arch/openrisc/include/asm/serial.h
index 270a45241639..cb5932f5447a 100644
--- a/arch/openrisc/include/asm/serial.h
+++ b/arch/openrisc/include/asm/serial.h
@@ -29,7 +29,7 @@
  * it needs to be correct to get the early console working.
  */
 
-#define BASE_BAUD (cpuinfo.clock_frequency/16)
+#define BASE_BAUD (cpuinfo_or1k[smp_processor_id()].clock_frequency/16)
 
 #endif /* __KERNEL__ */
 
diff --git a/arch/openrisc/include/asm/smp.h b/arch/openrisc/include/asm/smp.h
new file mode 100644
index 000000000000..e21d2f12b5b6
--- /dev/null
+++ b/arch/openrisc/include/asm/smp.h
@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2014 Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2.  This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ */
+
+#ifndef __ASM_OPENRISC_SMP_H
+#define __ASM_OPENRISC_SMP_H
+
+#include <asm/spr.h>
+#include <asm/spr_defs.h>
+
+#define raw_smp_processor_id()	(current_thread_info()->cpu)
+#define hard_smp_processor_id()	mfspr(SPR_COREID)
+
+extern void smp_init_cpus(void);
+
+extern void arch_send_call_function_single_ipi(int cpu);
+extern void arch_send_call_function_ipi_mask(const struct cpumask *mask);
+
+extern void set_smp_cross_call(void (*)(const struct cpumask *, unsigned int));
+extern void handle_IPI(unsigned int ipi_msg);
+
+#endif /* __ASM_OPENRISC_SMP_H */
diff --git a/arch/openrisc/include/asm/spr_defs.h b/arch/openrisc/include/asm/spr_defs.h
index 367dac70326a..154b5a1ee579 100644
--- a/arch/openrisc/include/asm/spr_defs.h
+++ b/arch/openrisc/include/asm/spr_defs.h
@@ -51,6 +51,11 @@
 #define SPR_ICCFGR	(SPRGROUP_SYS + 6)
 #define SPR_DCFGR	(SPRGROUP_SYS + 7)
 #define SPR_PCCFGR	(SPRGROUP_SYS + 8)
+#define SPR_VR2		(SPRGROUP_SYS + 9)
+#define SPR_AVR		(SPRGROUP_SYS + 10)
+#define SPR_EVBAR	(SPRGROUP_SYS + 11)
+#define SPR_AECR	(SPRGROUP_SYS + 12)
+#define SPR_AESR	(SPRGROUP_SYS + 13)
 #define SPR_NPC         (SPRGROUP_SYS + 16)  /* CZ 21/06/01 */
 #define SPR_SR		(SPRGROUP_SYS + 17)  /* CZ 21/06/01 */
 #define SPR_PPC         (SPRGROUP_SYS + 18)  /* CZ 21/06/01 */
@@ -61,6 +66,8 @@
 #define SPR_EEAR_LAST	(SPRGROUP_SYS + 63)
 #define SPR_ESR_BASE	(SPRGROUP_SYS + 64)
 #define SPR_ESR_LAST	(SPRGROUP_SYS + 79)
+#define SPR_COREID	(SPRGROUP_SYS + 128)
+#define SPR_NUMCORES	(SPRGROUP_SYS + 129)
 #define SPR_GPR_BASE	(SPRGROUP_SYS + 1024)
 
 /* Data MMU group */
@@ -135,12 +142,19 @@
 #define SPR_VR_CFG	0x00ff0000  /* Processor configuration */
 #define SPR_VR_RES	0x0000ffc0  /* Reserved */
 #define SPR_VR_REV	0x0000003f  /* Processor revision */
+#define SPR_VR_UVRP	0x00000040  /* Updated Version Registers Present */
 
 #define SPR_VR_VER_OFF	24
 #define SPR_VR_CFG_OFF	16
 #define SPR_VR_REV_OFF	0
 
 /*
+ * Bit definitions for the Version Register 2
+ */
+#define SPR_VR2_CPUID	0xff000000  /* Processor ID */
+#define SPR_VR2_VER	0x00ffffff  /* Processor version */
+
+/*
  * Bit definitions for the Unit Present Register
  *
  */
diff --git a/arch/openrisc/include/asm/time.h b/arch/openrisc/include/asm/time.h
new file mode 100644
index 000000000000..fe83a34a7d68
--- /dev/null
+++ b/arch/openrisc/include/asm/time.h
@@ -0,0 +1,15 @@
+/*
+ * OpenRISC timer API
+ *
+ * Copyright (C) 2017 by Stafford Horne (shorne@gmail.com)
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#ifndef __ASM_OR1K_TIME_H
+#define __ASM_OR1K_TIME_H
+
+extern void openrisc_clockevent_init(void);
+
+#endif /* __ASM_OR1K_TIME_H */
diff --git a/arch/openrisc/include/asm/tlbflush.h b/arch/openrisc/include/asm/tlbflush.h
index 6a2accd6cb67..94227f0eaf6d 100644
--- a/arch/openrisc/include/asm/tlbflush.h
+++ b/arch/openrisc/include/asm/tlbflush.h
@@ -33,13 +33,26 @@
  *  - flush_tlb_page(vma, vmaddr) flushes one page
  *  - flush_tlb_range(mm, start, end) flushes a range of pages
  */
+extern void local_flush_tlb_all(void);
+extern void local_flush_tlb_mm(struct mm_struct *mm);
+extern void local_flush_tlb_page(struct vm_area_struct *vma,
+				 unsigned long addr);
+extern void local_flush_tlb_range(struct vm_area_struct *vma,
+				  unsigned long start,
+				  unsigned long end);
 
-void flush_tlb_all(void);
-void flush_tlb_mm(struct mm_struct *mm);
-void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr);
-void flush_tlb_range(struct vm_area_struct *vma,
-		     unsigned long start,
-		     unsigned long end);
+#ifndef CONFIG_SMP
+#define flush_tlb_all	local_flush_tlb_all
+#define flush_tlb_mm	local_flush_tlb_mm
+#define flush_tlb_page	local_flush_tlb_page
+#define flush_tlb_range	local_flush_tlb_range
+#else
+extern void flush_tlb_all(void);
+extern void flush_tlb_mm(struct mm_struct *mm);
+extern void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr);
+extern void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
+			    unsigned long end);
+#endif
 
 static inline void flush_tlb(void)
 {