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Message-ID: <1422266761-24487-1-git-send-email-wenyou.yang@atmel.com>
Date: Mon, 26 Jan 2015 18:06:01 +0800
From: Wenyou Yang <wenyou.yang@...el.com>
To: <nicolas.ferre@...el.com>, <linux@....linux.org.uk>
CC: <linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>,
<alexandre.belloni@...e-electrons.com>,
<sylvain.rochet@...secur.com>, <peda@...ntia.se>,
<wenyou.yang@...el.com>, <Patrice.VILCHEZ@...el.com>
Subject: [PATCH 2/7] pm: at91: pm_suspend: add the WFI support for ARMv7
Signed-off-by: Wenyou Yang <wenyou.yang@...el.com>
---
arch/arm/mach-at91/pm_suspend.S | 54 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 53 insertions(+), 1 deletion(-)
diff --git a/arch/arm/mach-at91/pm_suspend.S b/arch/arm/mach-at91/pm_suspend.S
index 122a3f1..e796722 100644
--- a/arch/arm/mach-at91/pm_suspend.S
+++ b/arch/arm/mach-at91/pm_suspend.S
@@ -53,6 +53,58 @@ mode .req r6
beq 1b
.endm
+/*
+ * Put the processor to enter the WFI state
+ */
+ .macro _do_wfi
+
+#if defined(CONFIG_CPU_V7)
+ /*
+ * Execute an ISB instruction to flush the pipeline to ensure
+ * that all of operations have beem completed.
+ */
+ isb
+
+ /*
+ * Execute an ISB instruction to ensure that all of the
+ * CP15 register changes have been committed.
+ */
+ dsb
+ dmb
+
+ /* Disable the processor's clock */
+ mov tmp1, #AT91_PMC_PCK
+ str tmp1, [pmc, #AT91_PMC_SCDR]
+
+ /* Execute a WFI instruction */
+ wfi @ Wait For Interrupt
+
+ /*
+ * CPU can specualatively prefetch the instructions
+ * so add NOPs after WFI. Sixteen NOPs as Cortex-A5 pipeline.
+ */
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+ nop
+#else
+ mcr p15, 0, tmp1, c7, c0, 4
+#endif
+
+ .endm
+
.text
/*
@@ -181,7 +233,7 @@ sdr_sr_done:
skip_disable_main_clock:
/* Wait for interrupt */
- mcr p15, 0, tmp1, c7, c0, 4
+ _do_wfi
tst mode, #AT91_PM_SLOW_CLOCK
beq skip_enable_main_clock
--
1.7.9.5
--
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