[PATCH v4 1/3] Runtime Interpreted Power Sequences
From: Alexandre Courbot
Date: Thu Aug 16 2012 - 02:07:50 EST
Some device drivers (panel backlights especially) need to follow precise
sequences for powering on and off, involving gpios, regulators, PWMs
with a precise powering order and delays to respect between each steps.
These sequences are board-specific, and do not belong to a particular
driver - therefore they have been performed by board-specific hook
functions to far.
With the advent of the device tree and of ARM kernels that are not
board-tied, we cannot rely on these board-specific hooks anymore but
need a way to implement these sequences in a portable manner. This patch
introduces a simple interpreter that can execute such power sequences
encoded either as platform data or within the device tree.
Signed-off-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
---
.../devicetree/bindings/power_seq/power_seq.txt | 101 +++++
Documentation/power/power_seq.txt | 129 +++++++
drivers/power/Kconfig | 3 +
drivers/power/Makefile | 1 +
drivers/power/power_seq.c | 420 +++++++++++++++++++++
include/linux/power_seq.h | 142 +++++++
6 files changed, 796 insertions(+)
create mode 100644 Documentation/devicetree/bindings/power_seq/power_seq.txt
create mode 100644 Documentation/power/power_seq.txt
create mode 100644 drivers/power/power_seq.c
create mode 100644 include/linux/power_seq.h
diff --git a/Documentation/devicetree/bindings/power_seq/power_seq.txt b/Documentation/devicetree/bindings/power_seq/power_seq.txt
new file mode 100644
index 0000000..749c6e4
--- /dev/null
+++ b/Documentation/devicetree/bindings/power_seq/power_seq.txt
@@ -0,0 +1,101 @@
+Specifying Power Sequences in the Device Tree
+=============================================
+In the device tree, power sequences are specified as sub-nodes of the device
+node and reference resources declared by that device.
+
+For an introduction about runtime interpreted power sequences, see
+Documentation/power/power_seq.txt and include/linux/power_seq.h.
+
+Power Sequences Structure
+-------------------------
+Power sequences are sub-nodes that are named such as the device driver can find
+them. The driver's documentation should list the sequence names it recognizes.
+
+Inside a power sequence node are sub-nodes that describe the different steps
+of the sequence. Each step must be named sequentially, with the first step
+named step0, the second step1, etc. Failure to follow this rule will result in a
+parsing error.
+
+Power Sequences Steps
+---------------------
+Every step of a sequence describes an action to be performed on a resource. It
+generally includes a property named after the resource type, and which value
+references the resource to be used. Depending on the resource type, additional
+properties can be defined to control the action to be performed.
+
+Currently supported resource types are:
+- "delay", which should simply contain a delay in microseconds to wait before
+ going on with the rest of the sequence. It takes no additional property.
+- "regulator" contains the name of a regulator to be acquired using
+ regulator_get(). An additional property, either "enable" or "disable", must be
+ present to control whether the regulator should be enabled or disabled during
+ that step.
+- "pwm" is set to the name of a PWM acquired using pwm_get(). As with regulator,
+ an additional "enable" or "disable" property is required.
+- "gpio" contains the name of a GPIO to enable or disable using the same
+ additional property as regulator or pwm. The gpio is resolved by appending
+ "-gpio" to the given name and looking for a device property with a GPIO
+ phandle.
+
+Example
+-------
+Here are example sequences declared within a backlight device that use all the
+supported resources types:
+
+ backlight {
+ compatible = "pwm-backlight";
+ ...
+
+ /* resources used by the sequences */
+ pwms = <&pwm 2 5000000>;
+ pwm-names = "backlight";
+ power-supply = <&backlight_reg>;
+ enable-gpio = <&gpio 28 0>;
+
+ power-on-sequence {
+ step0 {
+ regulator = "power";
+ enable;
+ };
+ step1 {
+ delay = <10000>;
+ };
+ step2 {
+ pwm = "backlight";
+ enable;
+ };
+ step3 {
+ gpio = "enable";
+ enable;
+ };
+ };
+
+ power-off-sequence {
+ step0 {
+ gpio = "enable";
+ disable;
+ };
+ step1 {
+ pwm = "backlight";
+ disable;
+ };
+ step2 {
+ delay = <10000>;
+ };
+ step3 {
+ regulator = "power";
+ disable;
+ };
+ };
+ };
+
+The first part lists the PWM, regulator, and GPIO resources used by the
+sequences. These resources will be requested on behalf of the backlight device
+when the sequences are built and are declared according to their own framework
+in a way that makes them accessible by name.
+
+After the resources declaration, two sequences follow for powering the backlight
+on and off. Their names are specified by the pwm-backlight driver. Every step
+uses one of the "delay", "regulator", "pwm" or "gpio" properties to reference a
+previously-declared resource. Additional "enable" or "disable" properties are
+also used as needed.
diff --git a/Documentation/power/power_seq.txt b/Documentation/power/power_seq.txt
new file mode 100644
index 0000000..3ab4f93
--- /dev/null
+++ b/Documentation/power/power_seq.txt
@@ -0,0 +1,129 @@
+Runtime Interpreted Power Sequences
+===================================
+
+Problem
+-------
+One very common board-dependent code is the out-of-driver code that is used to
+turn a device on or off. For instance, SoC boards very commonly use a GPIO
+(abstracted to a regulator or not) to control the power supply of a backlight,
+disabling it when the backlight is not used in order to save power. The GPIO
+that should be used, however, as well as the exact power sequence that may
+also involve other resources, is board-dependent and thus unknown of the driver.
+
+This was previously addressed by having hooks in the device's platform data that
+are called whenever the state of the device might reflect a power change. This
+approach, however, introduces board-dependant code into the kernel and is not
+compatible with the device tree.
+
+The Runtime Interpreted Power Sequences (or power sequences for short) aims at
+turning this code into platform data or device tree nodes. Power sequences are
+described using a simple format and run by a simple interpreter whenever needed.
+This allows to remove the callback mechanism and makes the kernel less
+board-dependant.
+
+What are Power Sequences?
+-------------------------
+Power sequences are a series of sequential steps during which an action is
+performed on a resource. The supported resources so far are:
+- delay (just wait for the delay given in microseconds)
+- GPIO (enable or disable)
+- regulator (enable or disable)
+- PWM (enable or disable)
+
+Every step designates a resource type and parameters that are relevant to it.
+For instance, GPIO and PWMs can be enabled or disabled.
+
+When a power sequence is run, each of its step is executed sequentially until
+one step fails or the end of the sequence is reached.
+
+Power sequences can be declared as platform data or in the device tree.
+
+Platform Data Format
+--------------------
+All relevant data structures for declaring power sequences are located in
+include/linux/power_seq.h.
+
+The platform data is a static instance of simple array of
+platform_power_seq_step instances, each
+instance describing a step. The type as well as one of id or gpio members
+(depending on the type) must be specified. The last step must be of type
+POWER_SEQ_STOP. Regulator and PWM resources are identified by name. GPIO are
+identified by number. For example, the following sequence will turn on the
+"power" regulator of the device, wait 10ms, and set GPIO number 110 to 1:
+
+static struct platform_power_seq power_on_seq = {
+ .nb_steps = 3,
+ .steps = {
+ {
+ .type = POWER_SEQ_REGULATOR,
+ .regulator.regulator = "power",
+ .regulator.enable = 1,
+ },
+ {
+ .type = POWER_SEQ_DELAY,
+ .delay.delay_us = 10000,
+ },
+ {
+ .type = POWER_SEQ_GPIO,
+ .gpio.gpio = 110,
+ .gpio.enable = 1,
+ },
+ },
+};
+
+Device Tree
+-----------
+Power sequences can also be encoded as device tree nodes. The following
+properties and nodes are equivalent to the platform data defined previously:
+
+ power-supply = <&power_reg>;
+ switch-gpio = <&gpio 110 0>;
+
+ power-on-sequence {
+ step0 {
+ regulator = "power";
+ enable;
+ };
+ step1 {
+ delay = <10000>;
+ };
+ step2 {
+ gpio = "switch";
+ enable;
+ };
+ };
+
+See Documentation/devicetree/bindings/power_seq/power_seq.txt for the complete
+syntax of the bindings.
+
+Usage by Drivers and Resources Management
+-----------------------------------------
+Power sequences make use of resources that must be properly allocated and
+managed. The power_seq_build() function builds a power sequence from the
+platform data. It also takes care of resolving and allocating the resources
+referenced by the sequence if needed:
+
+ struct power_seq *power_seq_build(struct device *dev, struct list_head *ress,
+ struct platform_power_seq *pseq);
+
+The 'dev' argument is the device in the name of which the resources are to be
+allocated.
+
+The 'ress' argument is a list to which the resolved resources are appended. This
+avoids allocating a resource referenced in several power sequences multiple
+times.
+
+On success, the function returns a devm allocated resolved sequence that is
+ready to be passed to power_seq_run(). In case of failure, and error code is
+returned.
+
+A resolved power sequence returned by power_seq_build can be run by
+power_run_run():
+
+ int power_seq_run(power_seq *seq);
+
+It returns 0 if the sequence has successfully been run, or an error code if a
+problem occured.
+
+There is no need to explicitly free the resources used by the sequence as they
+are devm-allocated.
diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
index c1892f3..4172fe4 100644
--- a/drivers/power/Kconfig
+++ b/drivers/power/Kconfig
@@ -312,4 +312,7 @@ config AB8500_BATTERY_THERM_ON_BATCTRL
thermistor connected on BATCTRL ADC.
endif # POWER_SUPPLY
+config POWER_SEQ
+ bool
+
source "drivers/power/avs/Kconfig"
diff --git a/drivers/power/Makefile b/drivers/power/Makefile
index ee58afb..828859c 100644
--- a/drivers/power/Makefile
+++ b/drivers/power/Makefile
@@ -45,3 +45,4 @@ obj-$(CONFIG_CHARGER_MAX8997) += max8997_charger.o
obj-$(CONFIG_CHARGER_MAX8998) += max8998_charger.o
obj-$(CONFIG_POWER_AVS) += avs/
obj-$(CONFIG_CHARGER_SMB347) += smb347-charger.o
+obj-$(CONFIG_POWER_SEQ) += power_seq.o
diff --git a/drivers/power/power_seq.c b/drivers/power/power_seq.c
new file mode 100644
index 0000000..1dcdbe0
--- /dev/null
+++ b/drivers/power/power_seq.c
@@ -0,0 +1,420 @@
+/*
+ * power_seq.c - A simple power sequence interpreter for platform devices
+ * and device tree.
+ *
+ * Author: Alexandre Courbot <acourbot@xxxxxxxxxx>
+ *
+ * Copyright (c) 2012 NVIDIA Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ */
+
+#include <linux/power_seq.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/pwm.h>
+#include <linux/regulator/consumer.h>
+#include <linux/gpio.h>
+
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+
+struct power_seq_step {
+ /* Copy of the platform data */
+ struct platform_power_seq_step pdata;
+ /* Resolved resource */
+ struct power_seq_resource *resource;
+};
+
+struct power_seq {
+ struct device *dev;
+ unsigned int nb_steps;
+ struct power_seq_step steps[];
+};
+
+static char *res_names[POWER_SEQ_MAX] = {
+ [POWER_SEQ_DELAY] = "delay",
+ [POWER_SEQ_REGULATOR] = "regulator",
+ [POWER_SEQ_GPIO] = "gpio",
+ [POWER_SEQ_PWM] = "pwm",
+};
+
+static int power_seq_step_run(struct power_seq_step *step)
+{
+ struct platform_power_seq_step *pdata = &step->pdata;
+ int err = 0;
+
+ switch (pdata->type) {
+ case POWER_SEQ_DELAY:
+ usleep_range(pdata->delay.delay_us,
+ pdata->delay.delay_us + 1000);
+ break;
+#ifdef CONFIG_REGULATOR
+ case POWER_SEQ_REGULATOR:
+ if (pdata->regulator.enable)
+ err = regulator_enable(step->resource->regulator);
+ else
+ err = regulator_disable(step->resource->regulator);
+ break;
+#endif
+#ifdef CONFIG_PWM
+ case POWER_SEQ_PWM:
+ if (pdata->gpio.enable)
+ err = pwm_enable(step->resource->pwm);
+ else
+ pwm_disable(step->resource->pwm);
+ break;
+#endif
+#ifdef CONFIG_GPIOLIB
+ case POWER_SEQ_GPIO:
+ gpio_set_value_cansleep(pdata->gpio.gpio, pdata->gpio.enable);
+ break;
+#endif
+ /*
+ * should never happen unless the sequence includes a step which
+ * type does not have support compiled in
+ */
+ default:
+ return -EINVAL;
+ }
+
+ if (err < 0)
+ return err;
+
+ return 0;
+}
+
+int power_seq_run(struct power_seq *seq)
+{
+ struct device *dev = seq->dev;
+ int err, cpt;
+
+ if (!seq)
+ return 0;
+
+ for (cpt = 0; cpt < seq->nb_steps; cpt++) {
+ err = power_seq_step_run(&seq->steps[cpt]);
+ if (err) {
+ dev_err(dev, "error %d while running power sequence!\n",
+ err);
+ return err;
+ }
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(power_seq_run);
+
+#ifdef CONFIG_OF
+static int of_power_seq_enable_properties(struct device *dev,
+ struct device_node *node,
+ bool *enable)
+{
+ if (of_find_property(node, "enable", NULL)) {
+ *enable = true;
+ } else if (of_find_property(node, "disable", NULL)) {
+ *enable = false;
+ } else {
+ dev_err(dev, "missing enable or disable property!\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int of_parse_power_seq_step(struct device *dev, struct device_node *node,
+ struct platform_power_seq_step *step)
+{
+ struct property *res_id = NULL;
+ int i, err;
+
+ /* Try to find a meaningful name property */
+ for (i = 0; i < POWER_SEQ_MAX; i++) {
+ struct property *mprop;
+
+ mprop = of_find_property(node, res_names[i], NULL);
+ if (mprop) {
+ if (res_id) {
+ dev_err(dev,
+ "more than one resource in step!\n");
+ return -EINVAL;
+ }
+ step->type = i;
+ res_id = mprop;
+ }
+ }
+ if (!res_id) {
+ dev_err(dev, "missing resource property for power seq step!\n");
+ return -EINVAL;
+ }
+
+ /* Now parse resource-specific properties */
+ switch (step->type) {
+ case POWER_SEQ_DELAY:
+ err = of_property_read_u32(node, res_id->name,
+ &step->delay.delay_us);
+ if (err)
+ goto err_read_property;
+
+ break;
+
+ case POWER_SEQ_REGULATOR:
+ err = of_property_read_string(node, res_id->name,
+ &step->regulator.regulator);
+ if (err)
+ goto err_read_property;
+
+ err = of_power_seq_enable_properties(dev, node,
+ &step->regulator.enable);
+ if (err)
+ return err;
+
+ break;
+
+ case POWER_SEQ_PWM:
+ err = of_property_read_string(node, res_id->name,
+ &step->pwm.pwm);
+ if (err)
+ goto err_read_property;
+
+ err = of_power_seq_enable_properties(dev, node,
+ &step->pwm.enable);
+ if (err)
+ return err;
+
+ break;
+
+#ifdef CONFIG_OF_GPIO
+ case POWER_SEQ_GPIO:
+ {
+ char prop_name[32]; /* max size of property name */
+ const char *gpio_name;
+ int gpio;
+
+ err = of_property_read_string(node, res_id->name, &gpio_name);
+ if (err)
+ goto err_read_property;
+
+ /* Resolve the GPIO name */
+ snprintf(prop_name, 32, "%s-gpio", gpio_name);
+ gpio = of_get_named_gpio(dev->of_node, prop_name, 0);
+ if (gpio < 0) {
+ dev_err(dev, "cannot resolve gpio \"%s\"\n", gpio_name);
+ return gpio;
+ }
+ step->gpio.gpio = gpio;
+
+ err = of_power_seq_enable_properties(dev, node,
+ &step->gpio.enable);
+ if (err)
+ return err;
+
+ break;
+ }
+#endif /* CONFIG_OF_GPIO */
+
+ default:
+ dev_err(dev, "unhandled power sequence step type %s\n",
+ res_names[step->type]);
+ return -EINVAL;
+ }
+
+ return 0;
+
+err_read_property:
+ dev_err(dev, "cannot read %s property!", res_names[step->type]);
+ return -EINVAL;
+}
+
+struct platform_power_seq *of_parse_power_seq(struct device *dev,
+ struct device_node *node)
+{
+ struct device_node *child = NULL;
+ struct platform_power_seq *pseq;
+ int nb_steps = 0, size;
+ int err;
+
+ if (!node)
+ return ERR_PTR(-EINVAL);
+
+ nb_steps = of_get_child_count(node);
+ size = sizeof(pseq) + sizeof(struct platform_power_seq_step) * nb_steps;
+ pseq = devm_kzalloc(dev, size, GFP_KERNEL);
+ if (!pseq)
+ return ERR_PTR(-ENOMEM);
+ pseq->nb_steps = nb_steps;
+
+ for_each_child_of_node(node, child) {
+ unsigned int pos;
+
+ /* Check that the name's format is correct and within bounds */
+ if (strncmp("step", child->name, 4)) {
+ err = -EINVAL;
+ goto parse_error;
+ }
+
+ err = kstrtoint(child->name + 4, 10, &pos);
+ if (err < 0)
+ goto parse_error;
+
+ if (pos >= nb_steps || pseq->steps[pos].type != 0) {
+ err = -EINVAL;
+ goto parse_error;
+ }
+
+ err = of_parse_power_seq_step(dev, child, &pseq->steps[pos]);
+ if (err)
+ return ERR_PTR(err);
+ }
+
+ return pseq;
+
+parse_error:
+ dev_err(dev, "invalid power step name %s!\n", child->name);
+ return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(of_parse_power_seq);
+#endif /* CONFIG_OF */
+
+static
+struct power_seq_resource *power_seq_find_resource(struct list_head *ress,
+ struct platform_power_seq_step *step)
+{
+ struct power_seq_resource *res;
+
+ list_for_each_entry(res, ress, list) {
+ struct platform_power_seq_step *pdata = res->pdata;
+
+ if (pdata->type != step->type)
+ continue;
+
+ switch (pdata->type) {
+ case POWER_SEQ_REGULATOR:
+ if (!strcmp(pdata->regulator.regulator,
+ step->regulator.regulator))
+ return res;
+ break;
+ case POWER_SEQ_PWM:
+ if (!strcmp(pdata->pwm.pwm, step->pwm.pwm))
+ return res;
+ break;
+ case POWER_SEQ_GPIO:
+ if (pdata->gpio.gpio == step->gpio.gpio)
+ return res;
+ break;
+ default:
+ break;
+ }
+ }
+
+ return NULL;
+}
+
+static int power_seq_allocate_resource(struct device *dev,
+ struct power_seq_resource *res)
+{
+ struct platform_power_seq_step *pdata = res->pdata;
+ int err;
+
+ switch (pdata->type) {
+ case POWER_SEQ_DELAY:
+ break;
+#ifdef CONFIG_REGULATOR
+ case POWER_SEQ_REGULATOR:
+ res->regulator = devm_regulator_get(dev,
+ pdata->regulator.regulator);
+ if (IS_ERR(res->regulator)) {
+ dev_err(dev, "cannot get regulator \"%s\"\n",
+ pdata->regulator.regulator);
+ return PTR_ERR(res->regulator);
+ }
+ break;
+#endif
+#ifdef CONFIG_PWM
+ case POWER_SEQ_PWM:
+ res->pwm = devm_pwm_get(dev, pdata->pwm.pwm);
+ if (IS_ERR(res->pwm)) {
+ dev_err(dev, "cannot get pwm \"%s\"\n", pdata->pwm.pwm);
+ return PTR_ERR(res->pwm);
+ }
+ break;
+#endif
+#ifdef CONFIG_GPIOLIB
+ case POWER_SEQ_GPIO:
+ err = devm_gpio_request_one(dev, pdata->gpio.gpio,
+ GPIOF_OUT_INIT_HIGH, "backlight_gpio");
+ if (err) {
+ dev_err(dev, "cannot get gpio %d\n", pdata->gpio.gpio);
+ return err;
+ }
+ break;
+#endif
+ default:
+ dev_err(dev, "invalid resource type %d\n", pdata->type);
+ return -EINVAL;
+ break;
+ }
+
+ return 0;
+}
+
+struct power_seq *power_seq_build(struct device *dev, struct list_head *ress,
+ struct platform_power_seq *pseq)
+{
+ struct power_seq *seq;
+ struct power_seq_resource *res;
+ int cpt, err;
+
+ seq = devm_kzalloc(dev, sizeof(*seq) + sizeof(struct power_seq_step) *
+ pseq->nb_steps, GFP_KERNEL);
+ if (!seq)
+ return ERR_PTR(-ENOMEM);
+
+ seq->dev = dev;
+ seq->nb_steps = pseq->nb_steps;
+
+ for (cpt = 0; cpt < seq->nb_steps; cpt++) {
+ struct platform_power_seq_step *pstep = &pseq->steps[cpt];
+ struct power_seq_step *step = &seq->steps[cpt];
+
+ memcpy(&step->pdata, pstep, sizeof(step->pdata));
+
+ /* Delay steps have no resource */
+ if (pstep->type == POWER_SEQ_DELAY)
+ continue;
+
+ /* create resource node if not referenced already */
+ res = power_seq_find_resource(ress, pstep);
+ if (!res) {
+ res = devm_kzalloc(dev, sizeof(*res), GFP_KERNEL);
+ if (!res)
+ return ERR_PTR(-ENOMEM);
+ res->pdata = &step->pdata;
+
+ err = power_seq_allocate_resource(dev, res);
+ if (err < 0)
+ return ERR_PTR(err);
+
+ list_add(&res->list, ress);
+ }
+ step->resource = res;
+ }
+
+ return seq;
+}
+EXPORT_SYMBOL_GPL(power_seq_build);
+
+MODULE_AUTHOR("Alexandre Courbot <acourbot@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Runtime Interpreted Power Sequences");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/power_seq.h b/include/linux/power_seq.h
new file mode 100644
index 0000000..d9dd277
--- /dev/null
+++ b/include/linux/power_seq.h
@@ -0,0 +1,142 @@
+/*
+ * power_seq.h
+ *
+ * Simple interpreter for defining power sequences as platform data or device
+ * tree properties.
+ *
+ * Power sequences are designed to replace the callbacks typically used in
+ * board-specific files that implement board-specific power sequences of devices
+ * such as backlights. A power sequence is an array of resources (which can a
+ * regulator, a GPIO, a PWM, ...) with an action to perform on it (enable or
+ * disable) and optional pre and post step delays. By having them interpreted
+ * instead of arbitrarily executed, it is possible to describe these in the
+ * device tree and thus remove board-specific code from the kernel.
+ *
+ * Author: Alexandre Courbot <acourbot@xxxxxxxxxx>
+ *
+ * Copyright (c) 2012 NVIDIA Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ */
+
+#ifndef __LINUX_POWER_SEQ_H
+#define __LINUX_POWER_SEQ_H
+
+#include <linux/types.h>
+
+struct device;
+struct regulator;
+struct pwm_device;
+struct device_node;
+
+/**
+ * The different kinds of resources that can be controlled during the sequences.
+ */
+enum power_seq_res_type {
+ POWER_SEQ_DELAY,
+ POWER_SEQ_REGULATOR,
+ POWER_SEQ_PWM,
+ POWER_SEQ_GPIO,
+ POWER_SEQ_MAX,
+};
+
+struct platform_power_seq_delay_step {
+ unsigned int delay_us;
+};
+
+struct platform_power_seq_regulator_step {
+ const char *regulator;
+ bool enable;
+};
+
+struct platform_power_seq_pwm_step {
+ const char *pwm;
+ bool enable;
+};
+
+struct platform_power_seq_gpio_step {
+ int gpio;
+ bool enable;
+};
+
+/**
+ * Platform definition of power sequences. A sequence is an array of these,
+ * terminated by a STOP instance.
+ */
+struct platform_power_seq_step {
+ enum power_seq_res_type type;
+ union {
+ struct platform_power_seq_delay_step delay;
+ struct platform_power_seq_regulator_step regulator;
+ struct platform_power_seq_pwm_step pwm;
+ struct platform_power_seq_gpio_step gpio;
+ };
+};
+
+struct platform_power_seq {
+ unsigned int nb_steps;
+ struct platform_power_seq_step steps[];
+};
+
+/**
+ * We maintain a list of these to monitor which resources have already
+ * been met and allocated while building the sequences.
+ */
+struct power_seq_resource {
+ /* relevant for resolving the resource and knowing its type */
+ struct platform_power_seq_step *pdata;
+ /* resolved resource (if any) */
+ union {
+ struct regulator *regulator;
+ struct pwm_device *pwm;
+ };
+ struct list_head list;
+};
+
+struct power_seq_resource;
+struct power_seq;
+
+#ifdef CONFIG_OF
+/**
+ * Build a platform data sequence from a device tree node. Memory for the
+ * platform sequence is allocated using devm_kzalloc on dev and can be freed
+ * by devm_kfree after power_seq_build is called.
+ */
+struct platform_power_seq *of_parse_power_seq(struct device *dev,
+ struct device_node *node);
+#else
+struct platform_power_seq *of_parse_power_seq(struct device *dev,
+ struct device_node *node)
+{
+ return ERR_PTR(-EINVAL);
+}
+#endif
+
+/**
+ * Build a runnable power sequence from platform data, and add the resources
+ * it uses into ress. Memory for the sequence is allocated using devm_kzalloc
+ * on dev.
+ * @dev device that will use the power sequence. All resources will be
+ * devm-allocated against it.
+ * @ress list that holds the power_seq_resources already used by this device.
+ * Resources newly met in the sequence will be added to it.
+ * @pseq power sequence in platform format.
+ */
+struct power_seq *power_seq_build(struct device *dev, struct list_head *ress,
+ struct platform_power_seq *pseq);
+
+/**
+ * Run the given power sequence. Returns 0 on success, error code in case of
+ * failure.
+ */
+int power_seq_run(struct power_seq *seq);
+
+#endif
--
1.7.11.4
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