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

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

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;
 

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