regulator: i.MX anatop: Allow supply regulator

The anatop regulators are SoC internal LDO regulators usually supplied
by an external PMIC. This patch adds support for specifying the supply
from the device tree using the vin-supply property.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/anatop-regulator.txt

@@ -13,6 +13,7 @@ Optional properties:
 - anatop-delay-reg-offset: Anatop MFD step time register offset
 - anatop-delay-bit-shift: Bit shift for the step time register
 - anatop-delay-bit-width: Number of bits used in the step time register
+- vin-supply: The supply for this regulator
 
 Any property defined as part of the core regulator
 binding, defined in regulator.txt, can also be used.

drivers/regulator/anatop-regulator.c

@@ -30,6 +30,7 @@
 #include <linux/regmap.h>
 #include <linux/regulator/driver.h>
 #include <linux/regulator/of_regulator.h>
+#include <linux/regulator/machine.h>
 
 #define LDO_RAMP_UP_UNIT_IN_CYCLES      64 /* 64 cycles per step */
 #define LDO_RAMP_UP_FREQ_IN_MHZ         24 /* cycle based on 24M OSC */
@@ -199,6 +200,7 @@ static int anatop_regulator_probe(struct platform_device *pdev)
 	rdesc->owner = THIS_MODULE;
 
 	initdata = of_get_regulator_init_data(dev, np, rdesc);
+	initdata->supply_regulator = "vin";
 	sreg->initdata = initdata;
 
 	anatop_np = of_get_parent(np);
@@ -262,6 +264,7 @@ static int anatop_regulator_probe(struct platform_device *pdev)
 	rdesc->vsel_reg = sreg->control_reg;
 	rdesc->vsel_mask = ((1 << sreg->vol_bit_width) - 1) <<
 			   sreg->vol_bit_shift;
+	rdesc->min_dropout_uV = 125000;
 
 	config.dev = &pdev->dev;
 	config.init_data = initdata;