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authorNicolas Pitre <nicolas.pitre@linaro.org>2012-04-12 02:45:22 -0400
committerNicolas Pitre <nicolas.pitre@linaro.org>2013-04-24 10:36:59 -0400
commite8db288e05e588ad3f416b3a24354d60d02f35f2 (patch)
tree97a3ed1fa4e59d45ebc41d48b07d7c61fcff9ffc
parent0c91e7e07ebf08092bf8e28d8cd8d420732fc716 (diff)
downloadvexpress-lsk-e8db288e05e588ad3f416b3a24354d60d02f35f2.tar.gz
ARM: multi-cluster PM: secondary kernel entry code
CPUs in cluster based systems, such as big.LITTLE, have special needs when entering the kernel due to a hotplug event, or when resuming from a deep sleep mode. This is vectorized so multiple CPUs can enter the kernel in parallel without serialization. The mcpm prefix stands for "multi cluster power management", however this is usable on single cluster systems as well. Only the basic structure is introduced here. This will be extended with later patches. In order not to complexify things more than they currently have to, the planned work to make runtime adjusted MPIDR based indexing and dynamic memory allocation for cluster states is postponed to a later cycle. The MAX_NR_CLUSTERS and MAX_CPUS_PER_CLUSTER static definitions should be sufficient for those systems expected to be available in the near future. Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
-rw-r--r--arch/arm/Kconfig8
-rw-r--r--arch/arm/common/Makefile1
-rw-r--r--arch/arm/common/mcpm_entry.c22
-rw-r--r--arch/arm/common/mcpm_head.S86
-rw-r--r--arch/arm/include/asm/mcpm.h42
5 files changed, 159 insertions, 0 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 2c3bdce1513..2d17275b5df 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1599,6 +1599,14 @@ config HAVE_ARM_TWD
help
This options enables support for the ARM timer and watchdog unit
+config MCPM
+ bool "Multi-Cluster Power Management"
+ depends on CPU_V7 && SMP
+ help
+ This option provides the common power management infrastructure
+ for (multi-)cluster based systems, such as big.LITTLE based
+ systems.
+
choice
prompt "Memory split"
default VMSPLIT_3G
diff --git a/arch/arm/common/Makefile b/arch/arm/common/Makefile
index dc8dd0de5c0..b070671033a 100644
--- a/arch/arm/common/Makefile
+++ b/arch/arm/common/Makefile
@@ -11,3 +11,4 @@ obj-$(CONFIG_SHARP_PARAM) += sharpsl_param.o
obj-$(CONFIG_SHARP_SCOOP) += scoop.o
obj-$(CONFIG_PCI_HOST_ITE8152) += it8152.o
obj-$(CONFIG_ARM_TIMER_SP804) += timer-sp.o
+obj-$(CONFIG_MCPM) += mcpm_head.o mcpm_entry.o
diff --git a/arch/arm/common/mcpm_entry.c b/arch/arm/common/mcpm_entry.c
new file mode 100644
index 00000000000..7cbf70051ea
--- /dev/null
+++ b/arch/arm/common/mcpm_entry.c
@@ -0,0 +1,22 @@
+/*
+ * arch/arm/common/mcpm_entry.c -- entry point for multi-cluster PM
+ *
+ * Created by: Nicolas Pitre, March 2012
+ * Copyright: (C) 2012-2013 Linaro Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <asm/mcpm.h>
+#include <asm/cacheflush.h>
+
+extern unsigned long mcpm_entry_vectors[MAX_NR_CLUSTERS][MAX_CPUS_PER_CLUSTER];
+
+void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr)
+{
+ unsigned long val = ptr ? virt_to_phys(ptr) : 0;
+ mcpm_entry_vectors[cluster][cpu] = val;
+ sync_cache_w(&mcpm_entry_vectors[cluster][cpu]);
+}
diff --git a/arch/arm/common/mcpm_head.S b/arch/arm/common/mcpm_head.S
new file mode 100644
index 00000000000..68c9903075a
--- /dev/null
+++ b/arch/arm/common/mcpm_head.S
@@ -0,0 +1,86 @@
+/*
+ * arch/arm/common/mcpm_head.S -- kernel entry point for multi-cluster PM
+ *
+ * Created by: Nicolas Pitre, March 2012
+ * Copyright: (C) 2012-2013 Linaro Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/linkage.h>
+#include <asm/mcpm.h>
+
+ .macro pr_dbg string
+#if defined(CONFIG_DEBUG_LL) && defined(DEBUG)
+ b 1901f
+1902: .asciz "CPU"
+1903: .asciz " cluster"
+1904: .asciz ": \string"
+ .align
+1901: adr r0, 1902b
+ bl printascii
+ mov r0, r9
+ bl printhex8
+ adr r0, 1903b
+ bl printascii
+ mov r0, r10
+ bl printhex8
+ adr r0, 1904b
+ bl printascii
+#endif
+ .endm
+
+ .arm
+ .align
+
+ENTRY(mcpm_entry_point)
+
+ THUMB( adr r12, BSYM(1f) )
+ THUMB( bx r12 )
+ THUMB( .thumb )
+1:
+ mrc p15, 0, r0, c0, c0, 5 @ MPIDR
+ ubfx r9, r0, #0, #8 @ r9 = cpu
+ ubfx r10, r0, #8, #8 @ r10 = cluster
+ mov r3, #MAX_CPUS_PER_CLUSTER
+ mla r4, r3, r10, r9 @ r4 = canonical CPU index
+ cmp r4, #(MAX_CPUS_PER_CLUSTER * MAX_NR_CLUSTERS)
+ blo 2f
+
+ /* We didn't expect this CPU. Try to cheaply make it quiet. */
+1: wfi
+ wfe
+ b 1b
+
+2: pr_dbg "kernel mcpm_entry_point\n"
+
+ /*
+ * MMU is off so we need to get to mcpm_entry_vectors in a
+ * position independent way.
+ */
+ adr r5, 3f
+ ldr r6, [r5]
+ add r6, r5, r6 @ r6 = mcpm_entry_vectors
+
+mcpm_entry_gated:
+ ldr r5, [r6, r4, lsl #2] @ r5 = CPU entry vector
+ cmp r5, #0
+ wfeeq
+ beq mcpm_entry_gated
+ pr_dbg "released\n"
+ bx r5
+
+ .align 2
+
+3: .word mcpm_entry_vectors - .
+
+ENDPROC(mcpm_entry_point)
+
+ .bss
+ .align 5
+
+ .type mcpm_entry_vectors, #object
+ENTRY(mcpm_entry_vectors)
+ .space 4 * MAX_NR_CLUSTERS * MAX_CPUS_PER_CLUSTER
diff --git a/arch/arm/include/asm/mcpm.h b/arch/arm/include/asm/mcpm.h
new file mode 100644
index 00000000000..470a417d135
--- /dev/null
+++ b/arch/arm/include/asm/mcpm.h
@@ -0,0 +1,42 @@
+/*
+ * arch/arm/include/asm/mcpm.h
+ *
+ * Created by: Nicolas Pitre, April 2012
+ * Copyright: (C) 2012-2013 Linaro Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef MCPM_H
+#define MCPM_H
+
+/*
+ * Maximum number of possible clusters / CPUs per cluster.
+ *
+ * This should be sufficient for quite a while, while keeping the
+ * (assembly) code simpler. When this starts to grow then we'll have
+ * to consider dynamic allocation.
+ */
+#define MAX_CPUS_PER_CLUSTER 4
+#define MAX_NR_CLUSTERS 2
+
+#ifndef __ASSEMBLY__
+
+/*
+ * Platform specific code should use this symbol to set up secondary
+ * entry location for processors to use when released from reset.
+ */
+extern void mcpm_entry_point(void);
+
+/*
+ * This is used to indicate where the given CPU from given cluster should
+ * branch once it is ready to re-enter the kernel using ptr, or NULL if it
+ * should be gated. A gated CPU is held in a WFE loop until its vector
+ * becomes non NULL.
+ */
+void mcpm_set_entry_vector(unsigned cpu, unsigned cluster, void *ptr);
+
+#endif /* ! __ASSEMBLY__ */
+#endif