[U-Boot] [PATCH 0/2] sun7i: PSCI enhancements

[U-Boot] [PATCH 0/2] sun7i: PSCI enhancements

[Jan Kiszka]

This adds CPU offlining and PSCI v0.2 support. See patches for details.

Jan

Jan Kiszka (2):
  sun7i: Add support for taking CPUs offline via PSCI
  sun7i: Add PSCI v0.2 support

 arch/arm/cpu/armv7/psci.S             |  35 ++++-
 arch/arm/cpu/armv7/sunxi/psci.S       | 287 ++++++++++++++++++++++++++++++++++
 arch/arm/cpu/armv7/virt-dt.c          |   5 +-
 arch/arm/include/asm/arch-sunxi/cpu.h |   2 +
 arch/arm/include/asm/psci.h           |  24 ++-
 5 files changed, 343 insertions(+), 10 deletions(-)

-- 
1.8.4.5

[U-Boot] [PATCH 1/2] sun7i: Add support for taking CPUs offline via PSCI

[Jan Kiszka]

Based on the original version by Marc Zyngier. It adds a psci_cpu_off
implementation for the A20 SoC. The mechanism works by first preparing
the calling CPU to go offline (disable and flush cache, disable SMP),
then requesting CPU 0 to pull the plug. The request is sent as FIQ on
SGI15.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 arch/arm/cpu/armv7/sunxi/psci.S | 170 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 170 insertions(+)

diff --git a/arch/arm/cpu/armv7/sunxi/psci.S b/arch/arm/cpu/armv7/sunxi/psci.S
index a84807d..0aa4007 100644
--- a/arch/arm/cpu/armv7/sunxi/psci.S
+++ b/arch/arm/cpu/armv7/sunxi/psci.S
@@ -18,6 +18,7 @@
  */
 
 #include <config.h>
+#include <asm/gic.h>
 #include <asm/psci.h>
 #include <asm/arch/cpu.h>
 
@@ -38,6 +39,8 @@
 
 #define	ONE_MS			(CONFIG_SYS_CLK_FREQ / 1000)
 #define	TEN_MS			(10 * ONE_MS)
+#define	GICD_BASE		0x1c81000
+#define	GICC_BASE		0x1c82000
 
 .macro	timer_wait	reg, ticks
 	@ Program CNTP_TVAL
@@ -61,7 +64,27 @@
 
 .globl	psci_arch_init
 psci_arch_init:
+	movw	r4, #(GICD_BASE & 0xffff)
+	movt	r4, #(GICD_BASE >> 16)
+
+	ldr	r5, [r4, #GICD_IGROUPRn]
+	bic	r5, r5, #(1 << 15) 	@ SGI15 as Group-0
+	str	r5, [r4, #GICD_IGROUPRn]
+
+	mov	r5, #0			@ Set SGI15 priority to 0
+	strb	r5, [r4, #(GICD_IPRIORITYRn + 15)]
+
+	add	r4, r4, #0x1000		@ GICC address
+
+	mov	r5, #0xff
+	str	r5, [r4, #GICC_PMR]	@ Be cool with non-secure
+
+	ldr	r5, [r4, #GICC_CTLR]
+	orr	r5, r5, #(1 << 3)	@ Switch FIQEn on
+	str	r5, [r4, #GICC_CTLR]
+
 	mrc	p15, 0, r5, c1, c1, 0	@ Read SCR
+	orr	r5, r5, #4		@ Enable FIQ in monitor mode
 	bic	r5, r5, #1		@ Secure mode
 	mcr	p15, 0, r5, c1, c1, 0	@ Write SCR
 	isb
@@ -79,6 +102,77 @@ psci_arch_init:
 
 	bx	lr
 
+.globl	psci_fiq_enter
+psci_fiq_enter:
+	push	{r0-r12}
+
+	@ Switch to secure
+	mrc	p15, 0, r7, c1, c1, 0
+	bic	r8, r7, #1
+	mcr	p15, 0, r8, c1, c1, 0
+	isb
+
+	movw	r8, #(GICC_BASE & 0xffff)
+	movt	r8, #(GICC_BASE >> 16)
+	ldr	r9, [r8, #GICC_IAR]
+	movw	r10, #0x3ff
+	movt	r10, #0
+	cmp	r9, r10
+	beq	out
+	movw	r10, #0x3fe
+	cmp	r9, r10
+	beq	out
+	str	r9, [r8, #GICC_EOIR]
+	dsb
+
+	@ Compute CPU number
+	lsr	r9, r9, #10
+	and	r9, r9, #0xf
+
+	movw	r8, #(SUN7I_CPUCFG_BASE & 0xffff)
+	movt	r8, #(SUN7I_CPUCFG_BASE >> 16)
+
+	@ Wait for the core to enter WFI
+	lsl	r11, r9, #6		@ x64
+	add	r11, r11, r8
+
+1:	ldr	r10, [r11, #0x48]
+	tst	r10, #(1 << 2)
+	bne	2f
+	timer_wait r10, ONE_MS
+	b	1b
+
+	@ Reset CPU
+2:	mov	r10, #0
+	str	r10, [r11, #0x40]
+
+	@ Lock CPU
+	mov	r10, #1
+	lsl	r9, r10, r9		@ r9 is now CPU mask
+	ldr	r10, [r8, #0x1e4]
+	bic	r10, r10, r9
+	str	r10, [r8, #0x1e4]
+
+	@ Set power gating
+	ldr	r10, [r8, #0x1b4]
+	orr	r10, r10, #1
+	str	r10, [r8, #0x1b4]
+	timer_wait r10, ONE_MS
+
+	@ Activate power clamp
+	mov	r10, #1
+1:	str	r10, [r8, #0x1b0]
+	lsl	r10, r10, #1
+	orr	r10, r10, #1
+	tst	r10, #0x100
+	beq	1b
+
+	@ Restore security level
+out:	mcr	p15, 0, r7, c1, c1, 0
+
+	pop	{r0-r12}
+	subs    pc, lr, #4
+
 	@ r1 = target CPU
 	@ r2 = target PC
 .globl	psci_cpu_on
@@ -144,6 +238,53 @@ psci_cpu_on:
 _target_pc:
 	.word	0
 
+/* Imported from Linux kernel */
+v7_flush_dcache_all:
+	dmb					@ ensure ordering with previous memory accesses
+	mrc	p15, 1, r0, c0, c0, 1		@ read clidr
+	ands	r3, r0, #0x7000000		@ extract loc from clidr
+	mov	r3, r3, lsr #23			@ left align loc bit field
+	beq	finished			@ if loc is 0, then no need to clean
+	mov	r10, #0				@ start clean at cache level 0
+flush_levels:
+	add	r2, r10, r10, lsr #1		@ work out 3x current cache level
+	mov	r1, r0, lsr r2			@ extract cache type bits from clidr
+	and	r1, r1, #7			@ mask of the bits for current cache only
+	cmp	r1, #2				@ see what cache we have@this level
+	blt	skip				@ skip if no cache, or just i-cache
+	mrs     r9, cpsr			@ make cssr&csidr read atomic
+	mcr	p15, 2, r10, c0, c0, 0		@ select current cache level in cssr
+	isb					@ isb to sych the new cssr&csidr
+	mrc	p15, 1, r1, c0, c0, 0		@ read the new csidr
+	msr     cpsr_c, r9
+	and	r2, r1, #7			@ extract the length of the cache lines
+	add	r2, r2, #4			@ add 4 (line length offset)
+	ldr	r4, =0x3ff
+	ands	r4, r4, r1, lsr #3		@ find maximum number on the way size
+	clz	r5, r4				@ find bit position of way size increment
+	ldr	r7, =0x7fff
+	ands	r7, r7, r1, lsr #13		@ extract max number of the index size
+loop1:
+	mov	r9, r7				@ create working copy of max index
+loop2:
+	orr	r11, r10, r4, lsl r5		@ factor way and cache number into r11
+	orr	r11, r11, r9, lsl r2		@ factor index number into r11
+	mcr	p15, 0, r11, c7, c14, 2		@ clean & invalidate by set/way
+	subs	r9, r9, #1			@ decrement the index
+	bge	loop2
+	subs	r4, r4, #1			@ decrement the way
+	bge	loop1
+skip:
+	add	r10, r10, #2			@ increment cache number
+	cmp	r3, r10
+	bgt	flush_levels
+finished:
+	mov	r10, #0				@ swith back to cache level 0
+	mcr	p15, 2, r10, c0, c0, 0		@ select current cache level in cssr
+	dsb	st
+	isb
+	bx	lr
+
 _sunxi_cpu_entry:
 	@ Set SMP bit
 	mrc	p15, 0, r0, c1, c0, 1
@@ -158,5 +299,34 @@ _sunxi_cpu_entry:
 	ldr	r0, [r0]
 	b	_do_nonsec_entry
 
+.globl	psci_cpu_off
+psci_cpu_off:
+	mrc	p15, 0, r0, c1, c0, 0		@ SCTLR
+	bic	r0, r0, #(1 << 2)		@ Clear C bit
+	mcr	p15, 0, r0, c1, c0, 0		@ SCTLR
+	isb
+	dsb
+
+	bl	v7_flush_dcache_all
+
+	clrex					@ Why???
+
+	mrc	p15, 0, r0, c1, c0, 1		@ ACTLR
+	bic	r0, r0, #(1 << 6)		@ Clear SMP bit
+	mcr	p15, 0, r0, c1, c0, 1		@ ACTLR
+	isb
+	dsb
+
+	@ Ask CPU0 to pull the rug...
+	movw	r0, #(GICD_BASE & 0xffff)
+	movt	r0, #(GICD_BASE >> 16)
+	movw	r1, #15				@ SGI15
+	movt	r1, #1				@ Target is CPU0
+	str	r1, [r0, #GICD_SGIR]
+	dsb
+
+1:	wfi
+	b	1b
+
 text_end:
 	.popsection
-- 
1.8.4.5

[U-Boot] [PATCH 2/2] sun7i: Add PSCI v0.2 support

[Jan Kiszka]

This extends the PSCI support for the A20 to a dual v0.2 and v0.1
interface. Recent OSes will prefer v0.2, olders will still find the
original interface, just at v0.2 service IDs.

In addition to the existing services, v0.2 requires us to implement both
system off and reset. At least Linux will make use of them in favor of
its own implementations and, thus, fail if they do not work.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 arch/arm/cpu/armv7/psci.S             |  35 +++++++++-
 arch/arm/cpu/armv7/sunxi/psci.S       | 117 ++++++++++++++++++++++++++++++++++
 arch/arm/cpu/armv7/virt-dt.c          |   5 +-
 arch/arm/include/asm/arch-sunxi/cpu.h |   2 +
 arch/arm/include/asm/psci.h           |  24 +++++--
 5 files changed, 173 insertions(+), 10 deletions(-)

diff --git a/arch/arm/cpu/armv7/psci.S b/arch/arm/cpu/armv7/psci.S
index bf11a34..e2a38ca 100644
--- a/arch/arm/cpu/armv7/psci.S
+++ b/arch/arm/cpu/armv7/psci.S
@@ -49,8 +49,18 @@ ENTRY(psci_cpu_suspend)
 ENTRY(psci_cpu_off)
 ENTRY(psci_cpu_on)
 ENTRY(psci_migrate)
+ENTRY(psci_affinity_info)
+ENTRY(psci_migrate_info_type)
+ENTRY(psci_migrate_info_up_cpu)
+ENTRY(psci_system_off)
+ENTRY(psci_system_reset)
 	mov	r0, #ARM_PSCI_RET_NI	@ Return -1 (Not Implemented)
 	mov	pc, lr
+ENDPROC(psci_system_reset)
+ENDPROC(psci_system_off)
+ENDPROC(psci_migrate_info_up_cpu)
+ENDPROC(psci_migrate_info_type)
+ENDPROC(psci_affinity_info)
 ENDPROC(psci_migrate)
 ENDPROC(psci_cpu_on)
 ENDPROC(psci_cpu_off)
@@ -59,16 +69,33 @@ ENDPROC(psci_cpu_suspend)
 .weak psci_cpu_off
 .weak psci_cpu_on
 .weak psci_migrate
+.weak psci_affinity_info
+.weak psci_migrate_info_type
+.weak psci_migrate_info_up_cpu
+.weak psci_system_off
+.weak psci_system_reset
 
 _psci_table:
+	.word	ARM_PSCI_FN_PSCI_VERSION
+	.word	psci_version
 	.word	ARM_PSCI_FN_CPU_SUSPEND
 	.word	psci_cpu_suspend
 	.word	ARM_PSCI_FN_CPU_OFF
 	.word	psci_cpu_off
 	.word	ARM_PSCI_FN_CPU_ON
 	.word	psci_cpu_on
+	.word	ARM_PSCI_FN_AFFINITY_INFO
+	.word	psci_affinity_info
 	.word	ARM_PSCI_FN_MIGRATE
 	.word	psci_migrate
+	.word	ARM_PSCI_FN_MIGRATE_INFO_TYPE
+	.word	psci_migrate_info_type
+	.word	ARM_PSCI_FN_MIGRATE_INFO_UP_CPU
+	.word	psci_migrate_info_up_cpu
+	.word	ARM_PSCI_FN_SYSTEM_OFF
+	.word	psci_system_off
+	.word	ARM_PSCI_FN_SYSTEM_RESET
+	.word	psci_system_reset
 	.word	0
 	.word	0
 
@@ -86,7 +113,7 @@ _smc_psci:
 	ldr	r6, [r4, #4]		@ Load target PC
 	cmp	r5, #0			@ If reach the end, bail out
 	moveq	r0, #ARM_PSCI_RET_INVAL	@ Return -2 (Invalid)
-	beq	2f
+	beq	return
 	cmp	r0, r5			@ If not matching, try next entry
 	addne	r4, r4, #8
 	bne	1b
@@ -94,9 +121,13 @@ _smc_psci:
 	blx	r6			@ Execute PSCI function
 
 	@ Switch back to non-secure
-2:	mcr	p15, 0, r7, c1, c1, 0
+return:	mcr	p15, 0, r7, c1, c1, 0
 
 	pop	{r4-r7, lr}
 	movs	pc, lr			@ Return to the kernel
 
+psci_version:
+	mov	r0, #0x00000002		@ Version 0.2
+	b	return
+
 	.popsection
diff --git a/arch/arm/cpu/armv7/sunxi/psci.S b/arch/arm/cpu/armv7/sunxi/psci.S
index 0aa4007..bba1894 100644
--- a/arch/arm/cpu/armv7/sunxi/psci.S
+++ b/arch/arm/cpu/armv7/sunxi/psci.S
@@ -2,6 +2,9 @@
  * Copyright (C) 2013 - ARM Ltd
  * Author: Marc Zyngier <marc.zyngier@arm.com>
  *
+ * Copyright (C) Siemens AG, 2014
+ * Author: Jan Kiszka <jan.kiszka@siemens.com>
+ *
  * Based on code by Carl van Schaik <carl@ok-labs.com>.
  *
  * This program is free software; you can redistribute it and/or modify
@@ -42,6 +45,35 @@
 #define	GICD_BASE		0x1c81000
 #define	GICC_BASE		0x1c82000
 
+#define	TWI_DATA		0x0008
+#define	TWI_CNTR		0x000c
+#define	TWI_STAT		0x0010
+#define	TWI_CCR			0x0014
+#define	TWI_SRST		0x0018
+
+#define	TWI_CNTR_STOP		(1 << 4)
+#define	TWI_CNTR_START		(1 << 5)
+#define	TWI_CNTR_BUSEN		(1 << 6)
+
+#define	TWI_STAT_START_SENT	0x08
+#define	TWI_STAT_ADDR_ACK	0x18
+#define	TWI_STAT_DATA_ACK	0x28
+
+#define	TWI_CCR_100KHZ		((11 << 3) | 2)
+
+#define	AXP209_ADDR		0x34
+#define	AXP209_REG_SHUTDOWN	0x32
+#define	AXP209_SHUTDOWN_CTRL	0x80
+
+#define	WDOG_CTL		0x00
+#define	WDOG_MODE		0x04
+
+#define	WDOG_CTL_RSTART		(1 << 0)
+
+#define	WDOG_MODE_EN		(1 << 0)
+#define	WDOG_MODE_RSTEN		(1 << 1)
+#define	WDOG_MODE_0_5_S		(0x0 << 3)
+
 .macro	timer_wait	reg, ticks
 	@ Program CNTP_TVAL
 	movw	\reg, #(\ticks & 0xffff)
@@ -175,10 +207,13 @@ out:	mcr	p15, 0, r7, c1, c1, 0
 
 	@ r1 = target CPU
 	@ r2 = target PC
+	@ r3 = context (v0.2 only)
 .globl	psci_cpu_on
 psci_cpu_on:
 	adr	r0, _target_pc
 	str	r2, [r0]
+	adr	r0, _context
+	str	r3, [r0]
 	dsb
 
 	movw	r0, #(SUN7I_CPUCFG_BASE & 0xffff)
@@ -237,6 +272,8 @@ psci_cpu_on:
 
 _target_pc:
 	.word	0
+_context:
+	.word	0
 
 /* Imported from Linux kernel */
 v7_flush_dcache_all:
@@ -297,6 +334,8 @@ _sunxi_cpu_entry:
 
 	adr	r0, _target_pc
 	ldr	r0, [r0]
+	adr	r1, _context
+	ldr	r1, [r1]
 	b	_do_nonsec_entry
 
 .globl	psci_cpu_off
@@ -328,5 +367,83 @@ psci_cpu_off:
 1:	wfi
 	b	1b
 
+/*
+ * r0: TWI base address
+ * r1: state to wait for
+ */
+twi_wait:
+1:	ldr	r2, [r0, #TWI_STAT]		@ Read state
+	and	r2, r2, #0xff			@ Mask out state bits
+	cmp	r2, r1				@ State reached?
+	bne	1b
+
+	bx	lr
+
+/*
+ * r0: TWI base address
+ * r1: data value to be sent
+ */
+twi_send:
+	str	r1, [r0, #TWI_DATA]		@ Write outgoing data value
+	mov	r1, #(TWI_CNTR_BUSEN)		@ Trigger transmission
+	str	r1, [r0, #TWI_CNTR]
+
+	bx	lr
+
+.globl	psci_system_off
+psci_system_off:
+	movw	r0, #(SUNXI_TWI0_BASE & 0xffff)
+	movt	r0, #(SUNXI_TWI0_BASE >> 16)
+
+	@ Perform soft-reset
+	mov	r1, #0
+	str	r1, [r0, #TWI_SRST]
+
+	@ Configure speed
+	mov	r1, #TWI_CCR_100KHZ
+	str	r1, [r0, #TWI_CCR]
+
+	@ Send STOP (just in case), then transmit START condition
+	mov	r1, #(TWI_CNTR_BUSEN | TWI_CNTR_START | TWI_CNTR_STOP)
+	str	r1, [r0, #TWI_CNTR]
+	mov	r1, #TWI_STAT_START_SENT
+	bl	twi_wait
+
+	@ Send AXP209 address
+	mov	r1, #(AXP209_ADDR << 1)
+	bl	twi_send
+	mov	r1, #TWI_STAT_ADDR_ACK
+	bl	twi_wait
+
+	@ Select AXP209 register
+	mov	r1, #AXP209_REG_SHUTDOWN
+	bl	twi_send
+	mov	r1, #TWI_STAT_DATA_ACK
+	bl	twi_wait
+
+	@ Request shutdown
+	mov	r1, #AXP209_SHUTDOWN_CTRL
+	bl	twi_send
+	mov	r1, #TWI_STAT_DATA_ACK
+	bl	twi_wait
+
+	@ Complete the transmission with a STOP condition
+	mov	r1, #TWI_CNTR_STOP
+	str	r1, [r0, #TWI_CNTR]
+
+1:	b	1b
+
+.globl	psci_system_reset
+psci_system_reset:
+	movw	r0, #(SUNXI_WDOG_CTL & 0xffff)
+	movt	r0, #(SUNXI_WDOG_CTL >> 16)
+
+	mov	r1, #(WDOG_MODE_RSTEN | WDOG_MODE_EN | WDOG_MODE_0_5_S)
+	str	r1, [r0, #WDOG_MODE]
+
+	mov	r1, #WDOG_CTL_RSTART
+	str	r1, [r0, #WDOG_CTL]
+1:	b	1b
+
 text_end:
 	.popsection
diff --git a/arch/arm/cpu/armv7/virt-dt.c b/arch/arm/cpu/armv7/virt-dt.c
index 0b0d6a7..f529d51 100644
--- a/arch/arm/cpu/armv7/virt-dt.c
+++ b/arch/arm/cpu/armv7/virt-dt.c
@@ -66,7 +66,10 @@ static int fdt_psci(void *fdt)
 			return nodeoff;
 	}
 
-	tmp = fdt_setprop_string(fdt, nodeoff, "compatible", "arm,psci");
+	tmp = fdt_setprop_string(fdt, nodeoff, "compatible", "arm,psci-0.2");
+	if (tmp)
+		return tmp;
+	tmp = fdt_appendprop_string(fdt, nodeoff, "compatible", "arm,psci");
 	if (tmp)
 		return tmp;
 	tmp = fdt_setprop_string(fdt, nodeoff, "method", "smc");
diff --git a/arch/arm/include/asm/arch-sunxi/cpu.h b/arch/arm/include/asm/arch-sunxi/cpu.h
index 2c92b5c..e887e96 100644
--- a/arch/arm/include/asm/arch-sunxi/cpu.h
+++ b/arch/arm/include/asm/arch-sunxi/cpu.h
@@ -137,6 +137,8 @@
 
 #define SUNXI_BROM_BASE			0xffff0000	/* 32 kiB */
 
+#define SUNXI_WDOG_CTL			(SUNXI_TIMER_BASE + 0x90)
+
 #define SUNXI_CPU_CFG			(SUNXI_TIMER_BASE + 0x13c)
 
 #ifndef __ASSEMBLY__
diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
index 704b4b0..234475a 100644
--- a/arch/arm/include/asm/psci.h
+++ b/arch/arm/include/asm/psci.h
@@ -18,18 +18,28 @@
 #ifndef __ARM_PSCI_H__
 #define __ARM_PSCI_H__
 
-/* PSCI interface */
-#define ARM_PSCI_FN_BASE		0x95c1ba5e
-#define ARM_PSCI_FN(n)			(ARM_PSCI_FN_BASE + (n))
+#define ARM_PSCI_FN32_BASE		0x84000000
+#define ARM_PSCI_FN(n)			(ARM_PSCI_FN32_BASE + (n))
 
-#define ARM_PSCI_FN_CPU_SUSPEND		ARM_PSCI_FN(0)
-#define ARM_PSCI_FN_CPU_OFF		ARM_PSCI_FN(1)
-#define ARM_PSCI_FN_CPU_ON		ARM_PSCI_FN(2)
-#define ARM_PSCI_FN_MIGRATE		ARM_PSCI_FN(3)
+#define ARM_PSCI_FN_PSCI_VERSION	ARM_PSCI_FN(0)
+#define ARM_PSCI_FN_CPU_SUSPEND		ARM_PSCI_FN(1)
+#define ARM_PSCI_FN_CPU_OFF		ARM_PSCI_FN(2)
+#define ARM_PSCI_FN_CPU_ON		ARM_PSCI_FN(3)
+#define ARM_PSCI_FN_AFFINITY_INFO	ARM_PSCI_FN(4)
+#define ARM_PSCI_FN_MIGRATE		ARM_PSCI_FN(5)
+#define ARM_PSCI_FN_MIGRATE_INFO_TYPE	ARM_PSCI_FN(6)
+#define ARM_PSCI_FN_MIGRATE_INFO_UP_CPU	ARM_PSCI_FN(7)
+#define ARM_PSCI_FN_SYSTEM_OFF		ARM_PSCI_FN(8)
+#define ARM_PSCI_FN_SYSTEM_RESET	ARM_PSCI_FN(9)
 
 #define ARM_PSCI_RET_SUCCESS		0
 #define ARM_PSCI_RET_NI			(-1)
 #define ARM_PSCI_RET_INVAL		(-2)
 #define ARM_PSCI_RET_DENIED		(-3)
+#define ARM_PSCI_RET_ALREADY_ON		(-4)
+#define ARM_PSCI_RET_ON_PENDING		(-5)
+#define ARM_PSCI_RET_INTERNAL_FAILURE	(-6)
+#define ARM_PSCI_RET_NOT_PRESENT	(-7)
+#define ARM_PSCI_RET_DISABLED		(-8)
 
 #endif /* __ARM_PSCI_H__ */
-- 
1.8.4.5

[U-Boot] [PATCH 2/2] sun7i: Add PSCI v0.2 support

[Hans de Goede]

Hi,

On 15-12-14 12:37, Jan Kiszka wrote:
> This extends the PSCI support for the A20 to a dual v0.2 and v0.1
> interface. Recent OSes will prefer v0.2, olders will still find the
> original interface, just at v0.2 service IDs.
>
> In addition to the existing services, v0.2 requires us to implement both
> system off and reset. At least Linux will make use of them in favor of
> its own implementations and, thus, fail if they do not work.

Ugh, that may be a problem, as at least power off is highly SoC specific
(different pmics, and newer pmics have a different bus) and somewhat board
specific.

I think we may avoid adding any board specific stuff for now, since we
only want PSCI support on A20 and later and the only boards I know
of which are not using the standard axp pmics are all A10 / A13 boards,
but this might come back to bite us in the future.

Can't we just return -ENOTSUPPORTED or some such ?

Regards,

Hans


>
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>   arch/arm/cpu/armv7/psci.S             |  35 +++++++++-
>   arch/arm/cpu/armv7/sunxi/psci.S       | 117 ++++++++++++++++++++++++++++++++++
>   arch/arm/cpu/armv7/virt-dt.c          |   5 +-
>   arch/arm/include/asm/arch-sunxi/cpu.h |   2 +
>   arch/arm/include/asm/psci.h           |  24 +++++--
>   5 files changed, 173 insertions(+), 10 deletions(-)
>
> diff --git a/arch/arm/cpu/armv7/psci.S b/arch/arm/cpu/armv7/psci.S
> index bf11a34..e2a38ca 100644
> --- a/arch/arm/cpu/armv7/psci.S
> +++ b/arch/arm/cpu/armv7/psci.S
> @@ -49,8 +49,18 @@ ENTRY(psci_cpu_suspend)
>   ENTRY(psci_cpu_off)
>   ENTRY(psci_cpu_on)
>   ENTRY(psci_migrate)
> +ENTRY(psci_affinity_info)
> +ENTRY(psci_migrate_info_type)
> +ENTRY(psci_migrate_info_up_cpu)
> +ENTRY(psci_system_off)
> +ENTRY(psci_system_reset)
>   	mov	r0, #ARM_PSCI_RET_NI	@ Return -1 (Not Implemented)
>   	mov	pc, lr
> +ENDPROC(psci_system_reset)
> +ENDPROC(psci_system_off)
> +ENDPROC(psci_migrate_info_up_cpu)
> +ENDPROC(psci_migrate_info_type)
> +ENDPROC(psci_affinity_info)
>   ENDPROC(psci_migrate)
>   ENDPROC(psci_cpu_on)
>   ENDPROC(psci_cpu_off)
> @@ -59,16 +69,33 @@ ENDPROC(psci_cpu_suspend)
>   .weak psci_cpu_off
>   .weak psci_cpu_on
>   .weak psci_migrate
> +.weak psci_affinity_info
> +.weak psci_migrate_info_type
> +.weak psci_migrate_info_up_cpu
> +.weak psci_system_off
> +.weak psci_system_reset
>
>   _psci_table:
> +	.word	ARM_PSCI_FN_PSCI_VERSION
> +	.word	psci_version
>   	.word	ARM_PSCI_FN_CPU_SUSPEND
>   	.word	psci_cpu_suspend
>   	.word	ARM_PSCI_FN_CPU_OFF
>   	.word	psci_cpu_off
>   	.word	ARM_PSCI_FN_CPU_ON
>   	.word	psci_cpu_on
> +	.word	ARM_PSCI_FN_AFFINITY_INFO
> +	.word	psci_affinity_info
>   	.word	ARM_PSCI_FN_MIGRATE
>   	.word	psci_migrate
> +	.word	ARM_PSCI_FN_MIGRATE_INFO_TYPE
> +	.word	psci_migrate_info_type
> +	.word	ARM_PSCI_FN_MIGRATE_INFO_UP_CPU
> +	.word	psci_migrate_info_up_cpu
> +	.word	ARM_PSCI_FN_SYSTEM_OFF
> +	.word	psci_system_off
> +	.word	ARM_PSCI_FN_SYSTEM_RESET
> +	.word	psci_system_reset
>   	.word	0
>   	.word	0
>
> @@ -86,7 +113,7 @@ _smc_psci:
>   	ldr	r6, [r4, #4]		@ Load target PC
>   	cmp	r5, #0			@ If reach the end, bail out
>   	moveq	r0, #ARM_PSCI_RET_INVAL	@ Return -2 (Invalid)
> -	beq	2f
> +	beq	return
>   	cmp	r0, r5			@ If not matching, try next entry
>   	addne	r4, r4, #8
>   	bne	1b
> @@ -94,9 +121,13 @@ _smc_psci:
>   	blx	r6			@ Execute PSCI function
>
>   	@ Switch back to non-secure
> -2:	mcr	p15, 0, r7, c1, c1, 0
> +return:	mcr	p15, 0, r7, c1, c1, 0
>
>   	pop	{r4-r7, lr}
>   	movs	pc, lr			@ Return to the kernel
>
> +psci_version:
> +	mov	r0, #0x00000002		@ Version 0.2
> +	b	return
> +
>   	.popsection
> diff --git a/arch/arm/cpu/armv7/sunxi/psci.S b/arch/arm/cpu/armv7/sunxi/psci.S
> index 0aa4007..bba1894 100644
> --- a/arch/arm/cpu/armv7/sunxi/psci.S
> +++ b/arch/arm/cpu/armv7/sunxi/psci.S
> @@ -2,6 +2,9 @@
>    * Copyright (C) 2013 - ARM Ltd
>    * Author: Marc Zyngier <marc.zyngier@arm.com>
>    *
> + * Copyright (C) Siemens AG, 2014
> + * Author: Jan Kiszka <jan.kiszka@siemens.com>
> + *
>    * Based on code by Carl van Schaik <carl@ok-labs.com>.
>    *
>    * This program is free software; you can redistribute it and/or modify
> @@ -42,6 +45,35 @@
>   #define	GICD_BASE		0x1c81000
>   #define	GICC_BASE		0x1c82000
>
> +#define	TWI_DATA		0x0008
> +#define	TWI_CNTR		0x000c
> +#define	TWI_STAT		0x0010
> +#define	TWI_CCR			0x0014
> +#define	TWI_SRST		0x0018
> +
> +#define	TWI_CNTR_STOP		(1 << 4)
> +#define	TWI_CNTR_START		(1 << 5)
> +#define	TWI_CNTR_BUSEN		(1 << 6)
> +
> +#define	TWI_STAT_START_SENT	0x08
> +#define	TWI_STAT_ADDR_ACK	0x18
> +#define	TWI_STAT_DATA_ACK	0x28
> +
> +#define	TWI_CCR_100KHZ		((11 << 3) | 2)
> +
> +#define	AXP209_ADDR		0x34
> +#define	AXP209_REG_SHUTDOWN	0x32
> +#define	AXP209_SHUTDOWN_CTRL	0x80
> +
> +#define	WDOG_CTL		0x00
> +#define	WDOG_MODE		0x04
> +
> +#define	WDOG_CTL_RSTART		(1 << 0)
> +
> +#define	WDOG_MODE_EN		(1 << 0)
> +#define	WDOG_MODE_RSTEN		(1 << 1)
> +#define	WDOG_MODE_0_5_S		(0x0 << 3)
> +
>   .macro	timer_wait	reg, ticks
>   	@ Program CNTP_TVAL
>   	movw	\reg, #(\ticks & 0xffff)
> @@ -175,10 +207,13 @@ out:	mcr	p15, 0, r7, c1, c1, 0
>
>   	@ r1 = target CPU
>   	@ r2 = target PC
> +	@ r3 = context (v0.2 only)
>   .globl	psci_cpu_on
>   psci_cpu_on:
>   	adr	r0, _target_pc
>   	str	r2, [r0]
> +	adr	r0, _context
> +	str	r3, [r0]
>   	dsb
>
>   	movw	r0, #(SUN7I_CPUCFG_BASE & 0xffff)
> @@ -237,6 +272,8 @@ psci_cpu_on:
>
>   _target_pc:
>   	.word	0
> +_context:
> +	.word	0
>
>   /* Imported from Linux kernel */
>   v7_flush_dcache_all:
> @@ -297,6 +334,8 @@ _sunxi_cpu_entry:
>
>   	adr	r0, _target_pc
>   	ldr	r0, [r0]
> +	adr	r1, _context
> +	ldr	r1, [r1]
>   	b	_do_nonsec_entry
>
>   .globl	psci_cpu_off
> @@ -328,5 +367,83 @@ psci_cpu_off:
>   1:	wfi
>   	b	1b
>
> +/*
> + * r0: TWI base address
> + * r1: state to wait for
> + */
> +twi_wait:
> +1:	ldr	r2, [r0, #TWI_STAT]		@ Read state
> +	and	r2, r2, #0xff			@ Mask out state bits
> +	cmp	r2, r1				@ State reached?
> +	bne	1b
> +
> +	bx	lr
> +
> +/*
> + * r0: TWI base address
> + * r1: data value to be sent
> + */
> +twi_send:
> +	str	r1, [r0, #TWI_DATA]		@ Write outgoing data value
> +	mov	r1, #(TWI_CNTR_BUSEN)		@ Trigger transmission
> +	str	r1, [r0, #TWI_CNTR]
> +
> +	bx	lr
> +
> +.globl	psci_system_off
> +psci_system_off:
> +	movw	r0, #(SUNXI_TWI0_BASE & 0xffff)
> +	movt	r0, #(SUNXI_TWI0_BASE >> 16)
> +
> +	@ Perform soft-reset
> +	mov	r1, #0
> +	str	r1, [r0, #TWI_SRST]
> +
> +	@ Configure speed
> +	mov	r1, #TWI_CCR_100KHZ
> +	str	r1, [r0, #TWI_CCR]
> +
> +	@ Send STOP (just in case), then transmit START condition
> +	mov	r1, #(TWI_CNTR_BUSEN | TWI_CNTR_START | TWI_CNTR_STOP)
> +	str	r1, [r0, #TWI_CNTR]
> +	mov	r1, #TWI_STAT_START_SENT
> +	bl	twi_wait
> +
> +	@ Send AXP209 address
> +	mov	r1, #(AXP209_ADDR << 1)
> +	bl	twi_send
> +	mov	r1, #TWI_STAT_ADDR_ACK
> +	bl	twi_wait
> +
> +	@ Select AXP209 register
> +	mov	r1, #AXP209_REG_SHUTDOWN
> +	bl	twi_send
> +	mov	r1, #TWI_STAT_DATA_ACK
> +	bl	twi_wait
> +
> +	@ Request shutdown
> +	mov	r1, #AXP209_SHUTDOWN_CTRL
> +	bl	twi_send
> +	mov	r1, #TWI_STAT_DATA_ACK
> +	bl	twi_wait
> +
> +	@ Complete the transmission with a STOP condition
> +	mov	r1, #TWI_CNTR_STOP
> +	str	r1, [r0, #TWI_CNTR]
> +
> +1:	b	1b
> +
> +.globl	psci_system_reset
> +psci_system_reset:
> +	movw	r0, #(SUNXI_WDOG_CTL & 0xffff)
> +	movt	r0, #(SUNXI_WDOG_CTL >> 16)
> +
> +	mov	r1, #(WDOG_MODE_RSTEN | WDOG_MODE_EN | WDOG_MODE_0_5_S)
> +	str	r1, [r0, #WDOG_MODE]
> +
> +	mov	r1, #WDOG_CTL_RSTART
> +	str	r1, [r0, #WDOG_CTL]
> +1:	b	1b
> +
>   text_end:
>   	.popsection
> diff --git a/arch/arm/cpu/armv7/virt-dt.c b/arch/arm/cpu/armv7/virt-dt.c
> index 0b0d6a7..f529d51 100644
> --- a/arch/arm/cpu/armv7/virt-dt.c
> +++ b/arch/arm/cpu/armv7/virt-dt.c
> @@ -66,7 +66,10 @@ static int fdt_psci(void *fdt)
>   			return nodeoff;
>   	}
>
> -	tmp = fdt_setprop_string(fdt, nodeoff, "compatible", "arm,psci");
> +	tmp = fdt_setprop_string(fdt, nodeoff, "compatible", "arm,psci-0.2");
> +	if (tmp)
> +		return tmp;
> +	tmp = fdt_appendprop_string(fdt, nodeoff, "compatible", "arm,psci");
>   	if (tmp)
>   		return tmp;
>   	tmp = fdt_setprop_string(fdt, nodeoff, "method", "smc");
> diff --git a/arch/arm/include/asm/arch-sunxi/cpu.h b/arch/arm/include/asm/arch-sunxi/cpu.h
> index 2c92b5c..e887e96 100644
> --- a/arch/arm/include/asm/arch-sunxi/cpu.h
> +++ b/arch/arm/include/asm/arch-sunxi/cpu.h
> @@ -137,6 +137,8 @@
>
>   #define SUNXI_BROM_BASE			0xffff0000	/* 32 kiB */
>
> +#define SUNXI_WDOG_CTL			(SUNXI_TIMER_BASE + 0x90)
> +
>   #define SUNXI_CPU_CFG			(SUNXI_TIMER_BASE + 0x13c)
>
>   #ifndef __ASSEMBLY__
> diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
> index 704b4b0..234475a 100644
> --- a/arch/arm/include/asm/psci.h
> +++ b/arch/arm/include/asm/psci.h
> @@ -18,18 +18,28 @@
>   #ifndef __ARM_PSCI_H__
>   #define __ARM_PSCI_H__
>
> -/* PSCI interface */
> -#define ARM_PSCI_FN_BASE		0x95c1ba5e
> -#define ARM_PSCI_FN(n)			(ARM_PSCI_FN_BASE + (n))
> +#define ARM_PSCI_FN32_BASE		0x84000000
> +#define ARM_PSCI_FN(n)			(ARM_PSCI_FN32_BASE + (n))
>
> -#define ARM_PSCI_FN_CPU_SUSPEND		ARM_PSCI_FN(0)
> -#define ARM_PSCI_FN_CPU_OFF		ARM_PSCI_FN(1)
> -#define ARM_PSCI_FN_CPU_ON		ARM_PSCI_FN(2)
> -#define ARM_PSCI_FN_MIGRATE		ARM_PSCI_FN(3)
> +#define ARM_PSCI_FN_PSCI_VERSION	ARM_PSCI_FN(0)
> +#define ARM_PSCI_FN_CPU_SUSPEND		ARM_PSCI_FN(1)
> +#define ARM_PSCI_FN_CPU_OFF		ARM_PSCI_FN(2)
> +#define ARM_PSCI_FN_CPU_ON		ARM_PSCI_FN(3)
> +#define ARM_PSCI_FN_AFFINITY_INFO	ARM_PSCI_FN(4)
> +#define ARM_PSCI_FN_MIGRATE		ARM_PSCI_FN(5)
> +#define ARM_PSCI_FN_MIGRATE_INFO_TYPE	ARM_PSCI_FN(6)
> +#define ARM_PSCI_FN_MIGRATE_INFO_UP_CPU	ARM_PSCI_FN(7)
> +#define ARM_PSCI_FN_SYSTEM_OFF		ARM_PSCI_FN(8)
> +#define ARM_PSCI_FN_SYSTEM_RESET	ARM_PSCI_FN(9)
>
>   #define ARM_PSCI_RET_SUCCESS		0
>   #define ARM_PSCI_RET_NI			(-1)
>   #define ARM_PSCI_RET_INVAL		(-2)
>   #define ARM_PSCI_RET_DENIED		(-3)
> +#define ARM_PSCI_RET_ALREADY_ON		(-4)
> +#define ARM_PSCI_RET_ON_PENDING		(-5)
> +#define ARM_PSCI_RET_INTERNAL_FAILURE	(-6)
> +#define ARM_PSCI_RET_NOT_PRESENT	(-7)
> +#define ARM_PSCI_RET_DISABLED		(-8)
>
>   #endif /* __ARM_PSCI_H__ */
>

[U-Boot] [PATCH 2/2] sun7i: Add PSCI v0.2 support

[Jan Kiszka]

On 2014-12-15 12:44, Hans de Goede wrote:
> Hi,
> 
> On 15-12-14 12:37, Jan Kiszka wrote:
>> This extends the PSCI support for the A20 to a dual v0.2 and v0.1
>> interface. Recent OSes will prefer v0.2, olders will still find the
>> original interface, just at v0.2 service IDs.
>>
>> In addition to the existing services, v0.2 requires us to implement both
>> system off and reset. At least Linux will make use of them in favor of
>> its own implementations and, thus, fail if they do not work.
> 
> Ugh, that may be a problem, as at least power off is highly SoC specific
> (different pmics, and newer pmics have a different bus) and somewhat board
> specific.

Yes, that was my first thought as well.

> 
> I think we may avoid adding any board specific stuff for now, since we
> only want PSCI support on A20 and later and the only boards I know
> of which are not using the standard axp pmics are all A10 / A13 boards,
> but this might come back to bite us in the future.

Good - so this is a conceptual ack for this patch?

> 
> Can't we just return -ENOTSUPPORTED or some such ?

Unfortunately not. I don't know what was the intention of the designed
of this spec regarding mandatory SYSTEM_OFF and SYSTEM_RESET support.
Both functions are not supposed to return at all, and the kernel panics
when you return from SYSTEM_OFF.

Jan

-- 
Siemens AG, Corporate Technology, CT RTC ITP SES-DE
Corporate Competence Center Embedded Linux

[U-Boot] [PATCH 2/2] sun7i: Add PSCI v0.2 support

[Hans de Goede]

Hi,

On 15-12-14 16:27, Jan Kiszka wrote:
> On 2014-12-15 12:44, Hans de Goede wrote:
>> Hi,
>>
>> On 15-12-14 12:37, Jan Kiszka wrote:
>>> This extends the PSCI support for the A20 to a dual v0.2 and v0.1
>>> interface. Recent OSes will prefer v0.2, olders will still find the
>>> original interface, just at v0.2 service IDs.
>>>
>>> In addition to the existing services, v0.2 requires us to implement both
>>> system off and reset. At least Linux will make use of them in favor of
>>> its own implementations and, thus, fail if they do not work.
>>
>> Ugh, that may be a problem, as at least power off is highly SoC specific
>> (different pmics, and newer pmics have a different bus) and somewhat board
>> specific.
>
> Yes, that was my first thought as well.
>
>>
>> I think we may avoid adding any board specific stuff for now, since we
>> only want PSCI support on A20 and later and the only boards I know
>> of which are not using the standard axp pmics are all A10 / A13 boards,
>> but this might come back to bite us in the future.
>
> Good - so this is a conceptual ack for this patch?

I guess so I'm still not enthusiastic, but given that there seems no other
way (as you indicate below) and that for now I do not foresee any issues,
as long as we do a different psci.S per SoC (one for each of sun6i sun7i
and sun8i at least), we should be able to make this work.

So yes I can live with this. Note it still does not make me happy though
(not your fault).

>
>>
>> Can't we just return -ENOTSUPPORTED or some such ?
>
> Unfortunately not. I don't know what was the intention of the designed
> of this spec regarding mandatory SYSTEM_OFF and SYSTEM_RESET support.
> Both functions are not supposed to return at all, and the kernel panics
> when you return from SYSTEM_OFF.

Not nice, but nothing we can do to fix the retroactively.

Regards,

Hans

[U-Boot] [PATCH 1/2] sun7i: Add support for taking CPUs offline via PSCI

[Ian Campbell]

On Mon, 2014-12-15 at 12:37 +0100, Jan Kiszka wrote:
> +	movw	r8, #(GICC_BASE & 0xffff)
> +	movt	r8, #(GICC_BASE >> 16)
> +	ldr	r9, [r8, #GICC_IAR]
> +	movw	r10, #0x3ff
> +	movt	r10, #0
> +	cmp	r9, r10
> +	beq	out
> +	movw	r10, #0x3fe
> +	cmp	r9, r10
> +	beq	out
> +	str	r9, [r8, #GICC_EOIR]
> +	dsb

This block could do with a leading comment like the others. It is
reading IAR and discarding any spurious interrupts (1022+1023), but not
explicitly checking for SGI15, presumably because it can be asserted
that there is no other possible interrupt which can end up here, is that
right?

> +
> +.globl	psci_cpu_off
> +psci_cpu_off:
> +	mrc	p15, 0, r0, c1, c0, 0		@ SCTLR
> +	bic	r0, r0, #(1 << 2)		@ Clear C bit
> +	mcr	p15, 0, r0, c1, c0, 0		@ SCTLR
> +	isb
> +	dsb
> +
> +	bl	v7_flush_dcache_all
> +
> +	clrex					@ Why???

Anyone got any clues? (Just curiosity, not a blocker)

Apart from the comment:
Acked-by: Ian Campbell <ijc@hellion.org.uk>

Ian.

[U-Boot] [PATCH 2/2] sun7i: Add PSCI v0.2 support

[Ian Campbell]

On Mon, 2014-12-15 at 12:37 +0100, Jan Kiszka wrote:
> This extends the PSCI support for the A20 to a dual v0.2 and v0.1
> interface. Recent OSes will prefer v0.2, olders will still find the
> original interface, just at v0.2 service IDs.
> 
> In addition to the existing services, v0.2 requires us to implement both
> system off and reset. At least Linux will make use of them in favor of
> its own implementations and, thus, fail if they do not work.

What functionality does v0.2 give us over v0.1 that you are aiming to
expose here?

Ian.

[U-Boot] [PATCH 2/2] sun7i: Add PSCI v0.2 support

[Jan Kiszka]

On 2014-12-29 15:12, Ian Campbell wrote:
> On Mon, 2014-12-15 at 12:37 +0100, Jan Kiszka wrote:
>> This extends the PSCI support for the A20 to a dual v0.2 and v0.1
>> interface. Recent OSes will prefer v0.2, olders will still find the
>> original interface, just at v0.2 service IDs.
>>
>> In addition to the existing services, v0.2 requires us to implement both
>> system off and reset. At least Linux will make use of them in favor of
>> its own implementations and, thus, fail if they do not work.
> 
> What functionality does v0.2 give us over v0.1 that you are aiming to
> expose here?

For us, the added value is currently in next layer: we can simplify the
Jailhouse hypervisor a bit when leaving out v0.1 support right from the
beginning. But that means U-Boot has to support v0.2 on the platforms we
target at.

v0.2 is the current standard, so I would expect new boards to use that
one in the future by default. Thus, this lays the ground, though there
will surely be more work required to make some code better reusable.

Jan


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[U-Boot] [PATCH 1/2] sun7i: Add support for taking CPUs offline via PSCI

[Jan Kiszka]

On 2014-12-29 15:08, Ian Campbell wrote:
> On Mon, 2014-12-15 at 12:37 +0100, Jan Kiszka wrote:
>> +	movw	r8, #(GICC_BASE & 0xffff)
>> +	movt	r8, #(GICC_BASE >> 16)
>> +	ldr	r9, [r8, #GICC_IAR]
>> +	movw	r10, #0x3ff
>> +	movt	r10, #0
>> +	cmp	r9, r10
>> +	beq	out
>> +	movw	r10, #0x3fe
>> +	cmp	r9, r10
>> +	beq	out
>> +	str	r9, [r8, #GICC_EOIR]
>> +	dsb
> 
> This block could do with a leading comment like the others. It is
> reading IAR and discarding any spurious interrupts (1022+1023), but not
> explicitly checking for SGI15, presumably because it can be asserted
> that there is no other possible interrupt which can end up here, is that
> right?

That would be my interpretations as well: no other interrupt was routed
to the monitor. Will add a comment.

> 
>> +
>> +.globl	psci_cpu_off
>> +psci_cpu_off:
>> +	mrc	p15, 0, r0, c1, c0, 0		@ SCTLR
>> +	bic	r0, r0, #(1 << 2)		@ Clear C bit
>> +	mcr	p15, 0, r0, c1, c0, 0		@ SCTLR
>> +	isb
>> +	dsb
>> +
>> +	bl	v7_flush_dcache_all
>> +
>> +	clrex					@ Why???
> 
> Anyone got any clues? (Just curiosity, not a blocker)
> 
> Apart from the comment:
> Acked-by: Ian Campbell <ijc@hellion.org.uk>
> 

Thanks,
Jan


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[U-Boot] [PATCH 2/2] sun7i: Add PSCI v0.2 support

[Ian Campbell]

On Wed, 2014-12-31 at 12:57 +0100, Jan Kiszka wrote:
> On 2014-12-29 15:12, Ian Campbell wrote:
> > On Mon, 2014-12-15 at 12:37 +0100, Jan Kiszka wrote:
> >> This extends the PSCI support for the A20 to a dual v0.2 and v0.1
> >> interface. Recent OSes will prefer v0.2, olders will still find the
> >> original interface, just at v0.2 service IDs.
> >>
> >> In addition to the existing services, v0.2 requires us to implement both
> >> system off and reset. At least Linux will make use of them in favor of
> >> its own implementations and, thus, fail if they do not work.
> > 
> > What functionality does v0.2 give us over v0.1 that you are aiming to
> > expose here?
> 
> For us, the added value is currently in next layer: we can simplify the
> Jailhouse hypervisor a bit when leaving out v0.1 support right from the
> beginning. But that means U-Boot has to support v0.2 on the platforms we
> target at.

Understood, although we support both with Xen and it's really not very
much code.

> v0.2 is the current standard, so I would expect new boards to use that
> one in the future by default.

Given the extra complexity of v0.2 vs v0.1 for the firmware, and the
lack of compelling new features added by v0.2 for platforms which don't
run anything in secure world, I'm not sure that's a given. Indeed, that
was the thrust of my original question...

Ian.