spi: davinci: enable and power-up SPI only when required
Enable SPI only when active transfers are in progress. Keep
it in local low power when not in use.
Signed-off-by: Brian Niebuhr <bniebuhr@efjohnson.com>
Tested-By: Michael Williamson <michael.williamson@criticallink.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
diff --git a/drivers/spi/davinci_spi.c b/drivers/spi/davinci_spi.c
index 2e74fcd..1652bba 100644
--- a/drivers/spi/davinci_spi.c
+++ b/drivers/spi/davinci_spi.c
@@ -49,7 +49,6 @@
#define SPIFMT_WDELAY_SHIFT 24
#define SPIFMT_PRESCALE_SHIFT 8
-
/* SPIPC0 */
#define SPIPC0_DIFUN_MASK BIT(11) /* MISO */
#define SPIPC0_DOFUN_MASK BIT(10) /* MOSI */
@@ -67,6 +66,7 @@
/* SPIGCR1 */
#define SPIGCR1_CLKMOD_MASK BIT(1)
#define SPIGCR1_MASTER_MASK BIT(0)
+#define SPIGCR1_POWERDOWN_MASK BIT(8)
#define SPIGCR1_LOOPBACK_MASK BIT(16)
#define SPIGCR1_SPIENA_MASK BIT(24)
@@ -556,7 +556,7 @@
data1_reg_val = ioread32(davinci_spi->base + SPIDAT1);
- /* Enable SPI */
+ clear_io_bits(davinci_spi->base + SPIGCR1, SPIGCR1_POWERDOWN_MASK);
set_io_bits(davinci_spi->base + SPIGCR1, SPIGCR1_SPIENA_MASK);
INIT_COMPLETION(davinci_spi->done);
@@ -693,6 +693,9 @@
clear_io_bits(davinci_spi->base + SPIINT, SPIINT_DMA_REQ_EN);
}
+ clear_io_bits(davinci_spi->base + SPIGCR1, SPIGCR1_SPIENA_MASK);
+ set_io_bits(davinci_spi->base + SPIGCR1, SPIGCR1_POWERDOWN_MASK);
+
/*
* Check for bit error, desync error,parity error,timeout error and
* receive overflow errors
@@ -937,6 +940,7 @@
/* master mode default */
set_io_bits(davinci_spi->base + SPIGCR1, SPIGCR1_CLKMOD_MASK);
set_io_bits(davinci_spi->base + SPIGCR1, SPIGCR1_MASTER_MASK);
+ set_io_bits(davinci_spi->base + SPIGCR1, SPIGCR1_POWERDOWN_MASK);
ret = spi_bitbang_start(&davinci_spi->bitbang);
if (ret)
