Re: [linux-sunxi] Re: [PATCH] regulator: axp20x: Add support for the (external) drivebus regulator

From: Hans de Goede
Date: Sat May 28 2016 - 09:42:46 EST


On 16-05-16 19:06, Chen-Yu Tsai wrote:

On Sun, May 15, 2016 at 1:55 AM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
The axp20x pmics have 2 power inputs, one called ACIN which is intended
for to be supplied via a powerbarrel on the board and one called VBUS
which is intended to be supplied via an otg connector.

In the VBUS case the pmic needs to know if the board is supplying power
to the otg connector, because then it should not take any power from
its VBUS pin. The axp209 pmic has a N_VBUSEN input pin via which the
board can signal to the pmic whether the board is supplying power to the
otg connector or not.

On the axp221/axp223 this pin can alternatively be used as an output
which controls an external regulator which (optionally) supplies
power to the otg connector from the board. When the pin is used as
output it is called DRIVEBUS in the datasheet.

The datasheet actually calls it DRIVEVBUS. DRIVEBUS seems to be some
typo Allwinner has in their code.

Fixed for v2.

This commit adds support for the DRIVEBUS pin as an extra pmic
controlled regulator. Since this is optional a new x-powers,drivebus dt
property is added. When this is present the misc-control register is
written to change the N_VBUSEN input pin to DRIVEBUS output pin mode and
the extra drivebus regulator is registered with the regulator subsystem.

Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Documentation/devicetree/bindings/mfd/axp20x.txt | 5 ++++
drivers/regulator/axp20x-regulator.c | 30 ++++++++++++++++++++++++
2 files changed, 35 insertions(+)

diff --git a/Documentation/devicetree/bindings/mfd/axp20x.txt b/Documentation/devicetree/bindings/mfd/axp20x.txt
index d20b103..7a88479 100644
--- a/Documentation/devicetree/bindings/mfd/axp20x.txt
+++ b/Documentation/devicetree/bindings/mfd/axp20x.txt
@@ -22,6 +22,11 @@ Optional properties:
AXP152/20X: range: 750-1875, Default: 1.5 MHz
AXP22X/80X: range: 1800-4050, Default: 3 MHz

+- x-powers,drivebus: axp221 / axp223 only boolean, set this when the N_VBUSEN
+ pin is used as an output pin to control an external regulator
+ to drive the OTG VBus, rather then as an input pin which
+ signals whether the board is driving OTG VBus or not.

You should also add it to the regulators table further down in the binding.
And, as Rob mentioned, x-powers,drive-vbus-en (or drivevbus-en) is better
for a boolean property.

Both fixed for v2.

- <input>-supply: a phandle to the regulator supply node. May be omitted if
inputs are unregulated, such as using the IPSOUT output
from the PMIC.
diff --git a/drivers/regulator/axp20x-regulator.c b/drivers/regulator/axp20x-regulator.c
index 514a5e8..2422ddd 100644
--- a/drivers/regulator/axp20x-regulator.c
+++ b/drivers/regulator/axp20x-regulator.c
@@ -36,6 +36,8 @@

#define AXP20X_FREQ_DCDC_MASK 0x0f

#define AXP_DESC_IO(_family, _id, _match, _supply, _min, _max, _step, _vreg, \
_vmask, _ereg, _emask, _enable_val, _disable_val) \
[_family##_##_id] = { \
@@ -230,6 +232,18 @@ static const struct regulator_desc axp22x_regulators[] = {
AXP_DESC_FIXED(AXP22X, RTC_LDO, "rtc_ldo", "ips", 3000),

+static const struct regulator_desc axp22x_drivebus_regulator = {
+ .name = "drivebus",
+ .supply_name = "ips",

Given that you are approximating a gpio (in this case, the
controlled fixed voltage regulator, it would be better if you could:

a) have some way to specify the output voltage, so it looks like a fixed voltage
regulator that can be turned on/off.

This is fixed by your suggestion b) actually, if no get_voltage* ops are specified,
it will inherit the voltage of it supply.


b) have a separate supply name for this so it properly propagates enable/disable
calls. It would also pass the upstream voltage, thus behaving like a switch
you intended with the axp20x_ops_sw below.

Ack, fixed for v2.

Thanks for the review.