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| author | Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com> | 2020-11-10 11:19:58 +0300 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2020-11-10 20:31:38 +0300 |
| commit | b54a27d8109fc8f18cec3e0663f8e81ea727e3c6 (patch) | |
| tree | 3ff4d21a53772c88bbf6da200b1485e19f7ae7f3 | |
| parent | 1e908b2419ea828dfad9819e5c01322a93665356 (diff) | |
| download | linux-b54a27d8109fc8f18cec3e0663f8e81ea727e3c6.tar.xz | |
regulator: BD71847 support commonly used feedback connection
The BD71847 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/9b6b3d8233071d478f7d1e93b498f5a2141941e6.1604994184.git.matti.vaittinen@fi.rohmeurope.com
Signed-off-by: Mark Brown <broonie@kernel.org>
| -rw-r--r-- | Documentation/devicetree/bindings/regulator/rohm,bd71847-regulator.yaml | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/regulator/rohm,bd71847-regulator.yaml b/Documentation/devicetree/bindings/regulator/rohm,bd71847-regulator.yaml index eeac32cd15d6..a1b806373853 100644 --- a/Documentation/devicetree/bindings/regulator/rohm,bd71847-regulator.yaml +++ b/Documentation/devicetree/bindings/regulator/rohm,bd71847-regulator.yaml @@ -99,6 +99,55 @@ patternProperties: Enable/Disable control of this regulator must be left to the 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 |