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 2e74fcd2f423a2d58eff3eec9dd61102acbc28cb..1652bba955e23eb1723cd5db4311f16b8fd6bed8 100644 (file)
--- 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 @@ static int davinci_spi_bufs(struct spi_device *spi, struct spi_transfer *t)
 
        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 @@ static int davinci_spi_bufs(struct spi_device *spi, struct spi_transfer *t)
                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 @@ static int davinci_spi_probe(struct platform_device *pdev)
        /* 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)