diff options
| author | Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com> | 2020-11-10 10:19:38 +0200 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2020-11-10 17:31:34 +0000 |
| commit | 1e908b2419ea828dfad9819e5c01322a93665356 (patch) | |
| tree | de1116bb53a9c9056951f72329a6246d667b8f5f /Documentation/devicetree/bindings/regulator | |
| parent | 3cea11cd5e3b00d91caf0b4730194039b45c5891 (diff) | |
regulator: BD71837 support commonly used feedback connection
The BD71837 buck output voltages are in a few cases scaled using external
connection which adds a pull-up to regulator feedback pin. This connection
will adjust output voltage from regulator in a deterministic way.
Add support for describing this HW connection so that driver can adjust
voltage ranges accordingly.
Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Link: https://lore.kernel.org/r/9959924313db7c7165598604f9a07bf227f471a8.1604994184.git.matti.vaittinen@fi.rohmeurope.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'Documentation/devicetree/bindings/regulator')
| -rw-r--r-- | Documentation/devicetree/bindings/regulator/rohm,bd71837-regulator.yaml | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/regulator/rohm,bd71837-regulator.yaml b/Documentation/devicetree/bindings/regulator/rohm,bd71837-regulator.yaml index f5e31196a646..1941b36cf1ef 100644 --- a/Documentation/devicetree/bindings/regulator/rohm,bd71837-regulator.yaml +++ b/Documentation/devicetree/bindings/regulator/rohm,bd71837-regulator.yaml @@ -105,6 +105,54 @@ patternProperties: PMIC hardware state machine. type: boolean + # Setups where regulator (especially the buck8) output voltage is scaled + # by adding external connection where some other regulator output is + # connected to feedback-pin (over suitable resistors) is getting popular + # amongst users of BD71837. (This allows for example scaling down the + # buck8 voltages to suit lover GPU voltages for projects where buck8 is + # (ab)used to supply power for GPU. + # + # So we allow describing this external connection from DT and scale the + # voltages accordingly. This is what the connection should look like: + # + # |---------------| + # | buck 8 |-------+----->Vout + # | | | + # |---------------| | + # | | + # | | + # +-------+--R2----+ + # | + # R1 + # | + # V FB-pull-up + # + # Here the buck output is sifted according to formula: + # + # Vout_o = Vo - (Vpu - Vo)*R2/R1 + # Linear_step = step_orig*(R1+R2)/R1 + # + # where: + # Vout_o is adjusted voltage output at vsel reg value 0 + # Vo is original voltage output at vsel reg value 0 + # Vpu is the pull-up voltage V FB-pull-up in the picture + # R1 and R2 are resistor values. + + rohm,fb-pull-up-microvolt: + description: + Feedback-pin has pull-up connection to adjust voltage range. This is + the used pull-up voltage before R1. + + rohm,feedback-pull-up-r1-ohms: + description: + Feedback-pin has pull-up connection to adjust voltage range. This is + the used R1 resistor. + + rohm,feedback-pull-up-r2-ohms: + description: + Feedback-pin has pull-up connection to adjust voltage range. This is + the used R2 resistor. + required: - regulator-name |