mfd: Allow WM8994 LDO enable pulls to be disabled

In systems where the LDO enables are always driven (for example, being
connected to an always on supply rail or a GPIO which is driven by the
CPU even in suspend) then we can disable the pull downs on the LDO for
a small power savings.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

3 files changed, 28 insertions, 0 deletions

diff --git a/drivers/mfd/wm8994-core.c b/drivers/mfd/wm8994-core.c
index 96479c9b1728..1f15743460a0 100644
--- a/drivers/mfd/wm8994-core.c
+++ b/drivers/mfd/wm8994-core.c
@@ -281,6 +281,13 @@ static int wm8994_suspend(struct device *dev)
                 return 0;
         }
 
+        /* Disable LDO pulldowns while the device is suspended if we
+         * don't know that something will be driving them. */
+        if (!wm8994->ldo_ena_always_driven)
+                wm8994_set_bits(wm8994, WM8994_PULL_CONTROL_2,
+                                WM8994_LDO1ENA_PD | WM8994_LDO2ENA_PD,
+                                WM8994_LDO1ENA_PD | WM8994_LDO2ENA_PD);
+
         /* GPIO configuration state is saved here since we may be configuring
          * the GPIO alternate functions even if we're not using the gpiolib
          * driver for them.
@@ -350,6 +357,11 @@ static int wm8994_resume(struct device *dev)
         if (ret < 0)
                 dev_err(dev, "Failed to restore GPIO registers: %d\n", ret);
 
+        /* Disable LDO pulldowns while the device is active */
+        wm8994_set_bits(wm8994, WM8994_PULL_CONTROL_2,
+                        WM8994_LDO1ENA_PD | WM8994_LDO2ENA_PD,
+                        0);
+
         wm8994->suspended = false;
 
         return 0;
@@ -513,8 +525,15 @@ static int wm8994_device_init(struct wm8994 *wm8994, int irq)
                                                 pdata->gpio_defaults[i]);
                         }
                 }
+
+                wm8994->ldo_ena_always_driven = pdata->ldo_ena_always_driven;
         }
 
+        /* Disable LDO pulldowns while the device is active */
+        wm8994_set_bits(wm8994, WM8994_PULL_CONTROL_2,
+                        WM8994_LDO1ENA_PD | WM8994_LDO2ENA_PD,
+                        0);
+
         /* In some system designs where the regulators are not in use,
          * we can achieve a small reduction in leakage currents by
          * floating LDO outputs.  This bit makes no difference if the
diff --git a/include/linux/mfd/wm8994/core.h b/include/linux/mfd/wm8994/core.h
index f0b69cdae41c..5ab71bd76f9c 100644
--- a/include/linux/mfd/wm8994/core.h
+++ b/include/linux/mfd/wm8994/core.h
@@ -63,6 +63,8 @@ struct wm8994 {
 
         void *control_data;
 
+        bool ldo_ena_always_driven;
+
         int gpio_base;
         int irq_base;
 
diff --git a/include/linux/mfd/wm8994/pdata.h b/include/linux/mfd/wm8994/pdata.h
index 97cf4f27d647..ea32f306dca6 100644
--- a/include/linux/mfd/wm8994/pdata.h
+++ b/include/linux/mfd/wm8994/pdata.h
@@ -167,6 +167,13 @@ struct wm8994_pdata {
 
         /* WM8958 microphone bias configuration */
         int micbias[2];
+
+        /* Disable the internal pull downs on the LDOs if they are
+         * always driven (eg, connected to an always on supply or
+         * GPIO that always drives an output.  If they float power
+         * consumption will rise.
+         */
+        bool ldo_ena_always_driven;
 };
 
 #endif