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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>
This commit is contained in:
Mark Brown 2011-08-22 15:43:55 +02:00 committed by Samuel Ortiz
parent 862de70c12
commit 881de67046
3 changed files with 28 additions and 0 deletions
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19
drivers/mfd/wm8994-core.c
View File

@ -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

2
include/linux/mfd/wm8994/core.h
View File

@ -63,6 +63,8 @@ struct wm8994 {
void *control_data;
bool ldo_ena_always_driven;
int gpio_base;
int irq_base;

7
include/linux/mfd/wm8994/pdata.h
View File

@ -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