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Message-ID: <1405957142-19416-3-git-send-email-ttynkkynen@nvidia.com>
Date: Mon, 21 Jul 2014 18:38:48 +0300
From: Tuomas Tynkkynen <ttynkkynen@...dia.com>
To: <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>, <linux-pm@...r.kernel.org>
CC: Stephen Warren <swarren@...dotorg.org>,
Thierry Reding <thierry.reding@...il.com>,
Peter De Schrijver <pdeschrijver@...dia.com>,
Prashant Gaikwad <pgaikwad@...dia.com>,
Mike Turquette <mturquette@...aro.org>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Viresh Kumar <viresh.kumar@...aro.org>,
Paul Walmsley <pwalmsley@...dia.com>,
<devicetree@...r.kernel.org>,
Tuomas Tynkkynen <ttynkkynen@...dia.com>, <broonie@...nel.org>
Subject: [PATCH v2 02/16] regulator: Add helpers for low-level register access
Add helper functions that allow regulator consumers to obtain low-level
details about the regulator hardware, like the voltage selector register
address and such. These details can be useful when configuring hardware
or firmware that want to do low-level access to regulators, with no
involvement from the kernel.
The use-case for Tegra is a voltage-controlled oscillator clocksource
which has control logic to change the supply voltage via I2C to achieve
a desired output clock rate.
Signed-off-by: Tuomas Tynkkynen <ttynkkynen@...dia.com>
---
Documentation/power/regulator/consumer.txt | 35 +++++++++++++++
drivers/regulator/core.c | 71 ++++++++++++++++++++++++++++++
include/linux/regulator/consumer.h | 26 +++++++++++
3 files changed, 132 insertions(+)
diff --git a/Documentation/power/regulator/consumer.txt b/Documentation/power/regulator/consumer.txt
index 55c4175..81c0e2b 100644
--- a/Documentation/power/regulator/consumer.txt
+++ b/Documentation/power/regulator/consumer.txt
@@ -180,3 +180,38 @@ int regulator_unregister_notifier(struct regulator *regulator,
Regulators use the kernel notifier framework to send event to their interested
consumers.
+
+7. Regulator Direct Register Access
+===================================
+Some kinds of power management hardware or firmware are designed such that
+they need to do low-level hardware access to regulators, with no involvement
+from the kernel. Examples of such devices are:
+
+- clocksource with a voltage-controlled oscillator and control logic to change
+ the supply voltage over I2C to achieve a desired output clock rate
+- thermal management firmware that can issue an arbitrary I2C transaction to
+ perform system poweroff during overtemperature conditions
+
+To set up such a device/firmware, various parameters like I2C address of the
+regulator, addresses of various regulator registers etc. need to be configured
+to it. The regulator framework provides the following helpers for querying
+these details.
+
+Bus-specific details, like I2C addresses or transfer rates are handled by the
+regmap framework. To get the regulator's regmap (if supported), use :-
+
+struct regmap *regulator_get_regmap(struct regulator *regulator);
+
+To obtain the hardware register offset and bitmask for the regulator's voltage
+selector register, use :-
+
+int regulator_get_hardware_vsel_register(struct regulator *regulator,
+ unsigned *vsel_reg,
+ unsigned *vsel_mask);
+
+To convert a regulator framework voltage selector code (used by
+regulator_list_voltage) to a hardware-specific voltage selector that can be
+directly written to the voltage selector register, use :-
+
+int regulator_list_hardware_vsel(struct regulator *regulator,
+ unsigned selector);
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index c563d93..69c9c08 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -2228,6 +2228,77 @@ int regulator_list_voltage(struct regulator *regulator, unsigned selector)
EXPORT_SYMBOL_GPL(regulator_list_voltage);
/**
+ * regulator_get_regmap - get the regulator's register map
+ * @regulator: regulator source
+ *
+ * Returns the register map for the given regulator, or an ERR_PTR value
+ * if the regulator doesn't use regmap.
+ */
+struct regmap *regulator_get_regmap(struct regulator *regulator)
+{
+ struct regmap *map = regulator->rdev->regmap;
+
+ return map ? map : ERR_PTR(-EOPNOTSUPP);
+}
+
+/**
+ * regulator_get_hardware_vsel_register - get the HW voltage selector register
+ * @regulator: regulator source
+ * @vsel_reg: voltage selector register, output parameter
+ * @vsel_mask: mask for voltage selector bitfield, output parameter
+ *
+ * Returns the hardware register offset and bitmask used for setting the
+ * regulator voltage. This might be useful when configuring voltage-scaling
+ * hardware or firmware that can make I2C requests behind the kernel's back,
+ * for example.
+ *
+ * On success, the output parameters @vsel_reg and @vsel_mask are filled in
+ * and 0 is returned, otherwise a negative errno is returned.
+ */
+int regulator_get_hardware_vsel_register(struct regulator *regulator,
+ unsigned *vsel_reg,
+ unsigned *vsel_mask)
+{
+ struct regulator_dev *rdev = regulator->rdev;
+ struct regulator_ops *ops = rdev->desc->ops;
+
+ if (ops->set_voltage_sel != regulator_set_voltage_sel_regmap)
+ return -EOPNOTSUPP;
+
+ *vsel_reg = rdev->desc->vsel_reg;
+ *vsel_mask = rdev->desc->vsel_mask;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(regulator_get_hardware_vsel_register);
+
+/**
+ * regulator_list_hardware_vsel - get the HW-specific register value for a selector
+ * @regulator: regulator source
+ * @selector: identify voltage to list
+ *
+ * Converts the selector to a hardware-specific voltage selector that can be
+ * directly written to the regulator registers. The address of the voltage
+ * register can be determined by calling @regulator_get_hardware_vsel_register.
+ *
+ * On error a negative errno is returned.
+ */
+int regulator_list_hardware_vsel(struct regulator *regulator,
+ unsigned selector)
+{
+ struct regulator_dev *rdev = regulator->rdev;
+ struct regulator_ops *ops = rdev->desc->ops;
+
+ if (selector >= rdev->desc->n_voltages)
+ return -EINVAL;
+ if (ops->set_voltage_sel != regulator_set_voltage_sel_regmap)
+ return -EOPNOTSUPP;
+
+ return selector;
+}
+EXPORT_SYMBOL_GPL(regulator_list_hardware_vsel);
+
+/**
* regulator_get_linear_step - return the voltage step size between VSEL values
* @regulator: regulator source
*
diff --git a/include/linux/regulator/consumer.h b/include/linux/regulator/consumer.h
index 14ec18d..6bb5002 100644
--- a/include/linux/regulator/consumer.h
+++ b/include/linux/regulator/consumer.h
@@ -37,6 +37,7 @@
struct device;
struct notifier_block;
+struct regmap;
/*
* Regulator operating modes.
@@ -215,6 +216,13 @@ int regulator_set_optimum_mode(struct regulator *regulator, int load_uA);
int regulator_allow_bypass(struct regulator *regulator, bool allow);
+struct regmap *regulator_get_regmap(struct regulator *regulator);
+int regulator_get_hardware_vsel_register(struct regulator *regulator,
+ unsigned *vsel_reg,
+ unsigned *vsel_mask);
+int regulator_list_hardware_vsel(struct regulator *regulator,
+ unsigned selector);
+
/* regulator notifier block */
int regulator_register_notifier(struct regulator *regulator,
struct notifier_block *nb);
@@ -457,6 +465,24 @@ static inline int regulator_allow_bypass(struct regulator *regulator,
return 0;
}
+struct regmap *regulator_get_regmap(struct regulator *regulator)
+{
+ return ERR_PTR(-EOPNOTSUPP);
+}
+
+int regulator_get_hardware_vsel_register(struct regulator *regulator,
+ unsigned *vsel_reg,
+ unsigned *vsel_mask)
+{
+ return -EOPNOTSUPP;
+}
+
+int regulator_list_hardware_vsel(struct regulator *regulator,
+ unsigned selector)
+{
+ return -EOPNOTSUPP;
+}
+
static inline int regulator_register_notifier(struct regulator *regulator,
struct notifier_block *nb)
{
--
1.8.1.5
--
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