spi: fsl-espi: add (un)prepare_transfer_hardware calls to save power if SPI is not in use

Use (un)prepare_transfer_hardware calls to set fsl-espi to
low-power idle if not in use. Reference manual states:

"The eSPI is in a idle state and consumes minimal power.
The eSPI BRG is not functioning and the input clock is disabled"

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 35 insertions, 11 deletions

diff --git a/drivers/spi/spi-fsl-espi.c b/drivers/spi/spi-fsl-espi.c
index 90be6405e789..56cadf13519e 100644
--- a/drivers/spi/spi-fsl-espi.c
+++ b/drivers/spi/spi-fsl-espi.c
@@ -588,6 +588,38 @@ static void fsl_espi_remove(struct mpc8xxx_spi *mspi)
         iounmap(mspi->reg_base);
 }
 
+static int fsl_espi_suspend(struct spi_master *master)
+{
+        struct mpc8xxx_spi *mpc8xxx_spi;
+        struct fsl_espi_reg *reg_base;
+        u32 regval;
+
+        mpc8xxx_spi = spi_master_get_devdata(master);
+        reg_base = mpc8xxx_spi->reg_base;
+
+        regval = mpc8xxx_spi_read_reg(&reg_base->mode);
+        regval &= ~SPMODE_ENABLE;
+        mpc8xxx_spi_write_reg(&reg_base->mode, regval);
+
+        return 0;
+}
+
+static int fsl_espi_resume(struct spi_master *master)
+{
+        struct mpc8xxx_spi *mpc8xxx_spi;
+        struct fsl_espi_reg *reg_base;
+        u32 regval;
+
+        mpc8xxx_spi = spi_master_get_devdata(master);
+        reg_base = mpc8xxx_spi->reg_base;
+
+        regval = mpc8xxx_spi_read_reg(&reg_base->mode);
+        regval |= SPMODE_ENABLE;
+        mpc8xxx_spi_write_reg(&reg_base->mode, regval);
+
+        return 0;
+}
+
 static struct spi_master * fsl_espi_probe(struct device *dev,
                 struct resource *mem, unsigned int irq)
 {
@@ -614,6 +646,8 @@ static struct spi_master * fsl_espi_probe(struct device *dev,
         master->setup = fsl_espi_setup;
         master->cleanup = fsl_espi_cleanup;
         master->transfer_one_message = fsl_espi_do_one_msg;
+        master->prepare_transfer_hardware = fsl_espi_resume;
+        master->unprepare_transfer_hardware = fsl_espi_suspend;
 
         mpc8xxx_spi = spi_master_get_devdata(master);
         mpc8xxx_spi->spi_remove = fsl_espi_remove;
@@ -761,25 +795,15 @@ static int of_fsl_espi_remove(struct platform_device *dev)
 static int of_fsl_espi_suspend(struct device *dev)
 {
         struct spi_master *master = dev_get_drvdata(dev);
-        struct mpc8xxx_spi *mpc8xxx_spi;
-        struct fsl_espi_reg *reg_base;
-        u32 regval;
         int ret;
 
-        mpc8xxx_spi = spi_master_get_devdata(master);
-        reg_base = mpc8xxx_spi->reg_base;
-
         ret = spi_master_suspend(master);
         if (ret) {
                 dev_warn(dev, "cannot suspend master\n");
                 return ret;
         }
 
-        regval = mpc8xxx_spi_read_reg(&reg_base->mode);
-        regval &= ~SPMODE_ENABLE;
-        mpc8xxx_spi_write_reg(&reg_base->mode, regval);
-
-        return 0;
+        return fsl_espi_suspend(master);
 }
 
 static int of_fsl_espi_resume(struct device *dev)