linux-kernel - [PATCH v2 1/2] regulator: pickable ranges: don't always cache vsel

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Date: Mon, 20 May 2024 15:31:33 +0300
From: Matti Vaittinen <mazziesaccount@...il.com>
To: Matti Vaittinen <mazziesaccount@...il.com>,
	Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
Cc: Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>,
	Mårten Lindahl <marten.lindahl@...s.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/2] regulator: pickable ranges: don't always cache vsel

Some PMICs treat the vsel_reg same as apply-bit. Eg, when voltage range
is changed, the new voltage setting is not taking effect until the vsel
register is written.

Add a flag 'range_applied_by_vsel' to the regulator desc to indicate this
behaviour and to force the vsel value to be written to hardware if range
was changed, even if the old selector was same as the new one.

Signed-off-by: Matti Vaittinen <mazziesaccount@...il.com>

---
I have a feeling this same thing should be done with the apply-bit
writes. I just wonder why no-one has reported problems with it. Maybe
all the hardware with the apply bit has 'self clearing' apply register
marked as volatile? Anyways, I'll leave it out of this patch because I
have no hardware to test the apply-bit stuff, and as I haven't seen any
problem reports about it.
---
 drivers/regulator/helpers.c      | 43 ++++++++++++++++++++++----------
 include/linux/regulator/driver.h |  3 +++
 2 files changed, 33 insertions(+), 13 deletions(-)

diff --git a/drivers/regulator/helpers.c b/drivers/regulator/helpers.c
index d49268336553..6e1ace660b8c 100644
--- a/drivers/regulator/helpers.c
+++ b/drivers/regulator/helpers.c
@@ -161,6 +161,32 @@ int regulator_get_voltage_sel_pickable_regmap(struct regulator_dev *rdev)
 }
 EXPORT_SYMBOL_GPL(regulator_get_voltage_sel_pickable_regmap);
 
+static int write_separate_vsel_and_range(struct regulator_dev *rdev,
+					 unsigned int sel, unsigned int range)
+{
+	bool range_updated;
+	int ret;
+
+	ret = regmap_update_bits_base(rdev->regmap, rdev->desc->vsel_range_reg,
+				      rdev->desc->vsel_range_mask,
+				      range, &range_updated, false, false);
+	if (ret)
+		return ret;
+
+	/*
+	 * Some PMICs treat the vsel_reg same as apply-bit. Force it to be
+	 * written if the range changed, even if the old selector was same as
+	 * the new one
+	 */
+	if (rdev->desc->range_applied_by_vsel && range_updated)
+		return regmap_write_bits(rdev->regmap,
+					rdev->desc->vsel_reg,
+					rdev->desc->vsel_mask, sel);
+
+	return regmap_update_bits(rdev->regmap, rdev->desc->vsel_reg,
+				  rdev->desc->vsel_mask, sel);
+}
+
 /**
  * regulator_set_voltage_sel_pickable_regmap - pickable range set_voltage_sel
  *
@@ -199,21 +225,12 @@ int regulator_set_voltage_sel_pickable_regmap(struct regulator_dev *rdev,
 	range = rdev->desc->linear_range_selectors_bitfield[i];
 	range <<= ffs(rdev->desc->vsel_range_mask) - 1;
 
-	if (rdev->desc->vsel_reg == rdev->desc->vsel_range_reg) {
-		ret = regmap_update_bits(rdev->regmap,
-					 rdev->desc->vsel_reg,
+	if (rdev->desc->vsel_reg == rdev->desc->vsel_range_reg)
+		ret = regmap_update_bits(rdev->regmap, rdev->desc->vsel_reg,
 					 rdev->desc->vsel_range_mask |
 					 rdev->desc->vsel_mask, sel | range);
-	} else {
-		ret = regmap_update_bits(rdev->regmap,
-					 rdev->desc->vsel_range_reg,
-					 rdev->desc->vsel_range_mask, range);
-		if (ret)
-			return ret;
-
-		ret = regmap_update_bits(rdev->regmap, rdev->desc->vsel_reg,
-				  rdev->desc->vsel_mask, sel);
-	}
+	else
+		ret = write_separate_vsel_and_range(rdev, sel, range);
 
 	if (ret)
 		return ret;
diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
index 22a07c0900a4..f230a472ccd3 100644
--- a/include/linux/regulator/driver.h
+++ b/include/linux/regulator/driver.h
@@ -299,6 +299,8 @@ enum regulator_type {
  * @vsel_range_reg: Register for range selector when using pickable ranges
  *		    and ``regulator_map_*_voltage_*_pickable`` functions.
  * @vsel_range_mask: Mask for register bitfield used for range selector
+ * @range_applied_by_vsel: A flag to indicate that changes to vsel_range_reg
+ *			   are only effective after vsel_reg is written
  * @vsel_reg: Register for selector when using ``regulator_map_*_voltage_*``
  * @vsel_mask: Mask for register bitfield used for selector
  * @vsel_step: Specify the resolution of selector stepping when setting
@@ -389,6 +391,7 @@ struct regulator_desc {
 
 	unsigned int vsel_range_reg;
 	unsigned int vsel_range_mask;
+	bool range_applied_by_vsel;
 	unsigned int vsel_reg;
 	unsigned int vsel_mask;
 	unsigned int vsel_step;
-- 
2.45.1


-- 
Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~
Simon says - in Latin please.
~~~ "non cogito me" dixit Rene Descarte, deinde evanescavit ~~~
Thanks to Simon Glass for the translation =] 

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