From e8a8870d1dce4d5c978098715786802f586edf58 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Beno=C3=AEt=20Th=C3=A9baudeau?=
 <benoit.thebaudeau@advansee.com>
Date: Fri, 15 Nov 2013 15:58:44 +0100
Subject: [PATCH] cc2538: spi: Add enable and disable functions
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This makes it possible to reduce the power consumption when the SPI is unused.

Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
---
 cpu/cc2538/dev/spi.c  | 17 +++++++++++++++--
 cpu/cc2538/spi-arch.h | 15 +++++++++++++++
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/cpu/cc2538/dev/spi.c b/cpu/cc2538/dev/spi.c
index 42cf76999..191c77a62 100644
--- a/cpu/cc2538/dev/spi.c
+++ b/cpu/cc2538/dev/spi.c
@@ -74,8 +74,7 @@
 void
 spi_init(void)
 {
-  /* Enable the SSI peripheral */
-  REG(SYS_CTRL_RCGCSSI) |= 1;
+  spi_enable();
 
   /* Start by disabling the peripheral before configuring it */
   REG(SSI0_BASE + SSI_CR1) = 0;
@@ -110,4 +109,18 @@ spi_init(void)
   /* Enable the SSI */
   REG(SSI0_BASE + SSI_CR1) |= SSI_CR1_SSE;
 }
+/*---------------------------------------------------------------------------*/
+void
+spi_enable(void)
+{
+  /* Enable the clock for the SSI peripheral */
+  REG(SYS_CTRL_RCGCSSI) |= 1;
+}
+/*---------------------------------------------------------------------------*/
+void
+spi_disable(void)
+{
+  /* Gate the clock for the SSI peripheral */
+  REG(SYS_CTRL_RCGCSSI) &= ~1;
+}
 /** @} */
diff --git a/cpu/cc2538/spi-arch.h b/cpu/cc2538/spi-arch.h
index 3bace13d4..85eb058c1 100644
--- a/cpu/cc2538/spi-arch.h
+++ b/cpu/cc2538/spi-arch.h
@@ -57,6 +57,21 @@
 #define SPI_WAITFOREORx() do { \
   while(!(REG(SSI0_BASE + SSI_SR) & SSI_SR_RNE)); \
 } while (0)
+/*---------------------------------------------------------------------------*/
+/** \name Arch-specific SPI functions
+ * @{
+ */
+
+/** \brief Enables the SPI peripheral
+ */
+void spi_enable(void);
+
+/** \brief Disables the SPI peripheral
+ * \note Call this function to save power when the SPI is unused.
+ */
+void spi_disable(void);
+
+/** @} */
 
 #endif /* SPI_ARCH_H_ */