Message-ID: <1474342607-27512-3-git-send-email-peter.chen@nxp.com>
Date:   Tue, 20 Sep 2016 11:36:41 +0800
From:   Peter Chen <peter.chen@....com>
To:     <gregkh@...uxfoundation.org>, <stern@...land.harvard.edu>,
        <ulf.hansson@...aro.org>, <broonie@...nel.org>, <sre@...nel.org>,
        <robh+dt@...nel.org>, <shawnguo@...nel.org>,
        <dbaryshkov@...il.com>, <dwmw3@...radead.org>
CC:     <k.kozlowski@...sung.com>, <linux-arm-kernel@...ts.infradead.org>,
        <p.zabel@...gutronix.de>, <devicetree@...r.kernel.org>,
        <pawel.moll@....com>, <mark.rutland@....com>,
        <linux-usb@...r.kernel.org>, <arnd@...db.de>,
        <s.hauer@...gutronix.de>, <mail@...iej.szmigiero.name>,
        <troy.kisky@...ndarydevices.com>, <festevam@...il.com>,
        <oscar@...andei.net>, <stephen.boyd@...aro.org>,
        <linux-pm@...r.kernel.org>, <stillcompiling@...il.com>,
        <linux-kernel@...r.kernel.org>, <mka@...omium.org>,
        <vaibhav.hiremath@...aro.org>, Peter Chen <peter.chen@....com>
Subject: [PATCH v7 2/8] power: add power sequence library

We have an well-known problem that the device needs to do some power
sequence before it can be recognized by related host, the typical
example like hard-wired mmc devices and usb devices.

This power sequence is hard to be described at device tree and handled by
related host driver, so we have created a common power sequence
library to cover this requirement. The core code has supplied
some common helpers for host driver, and individual power sequence
libraries handle kinds of power sequence for devices.

pwrseq_generic is intended for general purpose of power sequence, which
handles gpios and clocks currently, and can cover regulator and pinctrl
in future. The host driver just needs to call of_pwrseq_on/of_pwrseq_off
if only one power sequence is needed, else call of_pwrseq_on_list
/of_pwrseq_off_list instead (eg, USB hub driver).

Signed-off-by: Peter Chen <peter.chen@....com>
Tested-by Joshua Clayton <stillcompiling@...il.com>
Reviewed-by: Matthias Kaehlcke <mka@...omium.org>
Tested-by: Matthias Kaehlcke <mka@...omium.org>
---
 MAINTAINERS                                     |   9 ++
 drivers/power/Kconfig                           |   1 +
 drivers/power/Makefile                          |   1 +
 drivers/power/pwrseq/Kconfig                    |  45 ++++++
 drivers/power/pwrseq/Makefile                   |   3 +
 drivers/power/pwrseq/core.c                     | 190 ++++++++++++++++++++++++
 drivers/power/pwrseq/pwrseq_compatible_sample.c | 178 ++++++++++++++++++++++
 drivers/power/pwrseq/pwrseq_generic.c           | 177 ++++++++++++++++++++++
 include/linux/power/pwrseq.h                    |  73 +++++++++
 9 files changed, 677 insertions(+)
 create mode 100644 drivers/power/pwrseq/Kconfig
 create mode 100644 drivers/power/pwrseq/Makefile
 create mode 100644 drivers/power/pwrseq/core.c
 create mode 100644 drivers/power/pwrseq/pwrseq_compatible_sample.c
 create mode 100644 drivers/power/pwrseq/pwrseq_generic.c
 create mode 100644 include/linux/power/pwrseq.h

diff --git a/MAINTAINERS b/MAINTAINERS
index b3e9395..b353769 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9343,6 +9343,15 @@ F:	include/linux/pm_*
 F:	include/linux/powercap.h
 F:	drivers/powercap/
 
+POWER SEQUENCE LIBRARY
+M:	Peter Chen <Peter.Chen@....com>
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/peter.chen/usb.git
+L:	linux-pm@...r.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/power/pwrseq/
+F:	drivers/power/pwrseq/
+F:	include/linux/power/pwrseq.h/
+
 POWER SUPPLY CLASS/SUBSYSTEM and DRIVERS
 M:	Sebastian Reichel <sre@...nel.org>
 M:	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>
diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
index acd4a15..f6aa4fd 100644
--- a/drivers/power/Kconfig
+++ b/drivers/power/Kconfig
@@ -515,3 +515,4 @@ endif # POWER_SUPPLY
 
 source "drivers/power/reset/Kconfig"
 source "drivers/power/avs/Kconfig"
+source "drivers/power/pwrseq/Kconfig"
diff --git a/drivers/power/Makefile b/drivers/power/Makefile
index e46b75d..4ed2e12 100644
--- a/drivers/power/Makefile
+++ b/drivers/power/Makefile
@@ -74,3 +74,4 @@ obj-$(CONFIG_CHARGER_TPS65217)	+= tps65217_charger.o
 obj-$(CONFIG_POWER_RESET)	+= reset/
 obj-$(CONFIG_AXP288_FUEL_GAUGE) += axp288_fuel_gauge.o
 obj-$(CONFIG_AXP288_CHARGER)	+= axp288_charger.o
+obj-$(CONFIG_POWER_SEQUENCE)	+= pwrseq/
diff --git a/drivers/power/pwrseq/Kconfig b/drivers/power/pwrseq/Kconfig
new file mode 100644
index 0000000..dff5e35
--- /dev/null
+++ b/drivers/power/pwrseq/Kconfig
@@ -0,0 +1,45 @@
+#
+# Power Sequence library
+#
+
+config POWER_SEQUENCE
+	bool
+
+menu "Power Sequence Support"
+
+config PWRSEQ_GENERIC
+	bool "Generic power sequence control"
+	depends on OF
+	select POWER_SEQUENCE
+	help
+	   It is used for drivers which needs to do power sequence
+	   (eg, turn on clock, toggle reset gpio) before the related
+	   devices can be found by hardware. This generic one can be
+	   used for common power sequence control.
+
+config PWRSEQ_GENERIC_INSTANCE_NUMBER
+	int "Number of Generic Power Sequence Instance"
+	depends on PWRSEQ_GENERIC
+	range 1 10
+	default 2
+	help
+	   Usually, there are not so many devices needs power sequence, we set two
+	   as default value.
+
+config PWRSEQ_SAMPLE
+	bool "sample power sequence control using compatible string"
+	depends on OF
+	select POWER_SEQUENCE
+	help
+	   It is a sample library which implements power sequence for device id,
+	   it is an example purpose.
+
+config PWRSEQ_SAMPLE_INSTANCE_NUMBER
+	int "Number of Sample Power Sequence Instance"
+	depends on PWRSEQ_SAMPLE
+	range 1 5
+	default 1
+	help
+	   Usually, this file is special for certain device, so the default for this number
+	   is 1.
+endmenu
diff --git a/drivers/power/pwrseq/Makefile b/drivers/power/pwrseq/Makefile
new file mode 100644
index 0000000..62f3cbf
--- /dev/null
+++ b/drivers/power/pwrseq/Makefile
@@ -0,0 +1,3 @@
+obj-$(CONFIG_POWER_SEQUENCE) += core.o
+obj-$(CONFIG_PWRSEQ_GENERIC) += pwrseq_generic.o
+obj-$(CONFIG_PWRSEQ_SAMPLE) += pwrseq_compatible_sample.o
diff --git a/drivers/power/pwrseq/core.c b/drivers/power/pwrseq/core.c
new file mode 100644
index 0000000..6beae20
--- /dev/null
+++ b/drivers/power/pwrseq/core.c
@@ -0,0 +1,190 @@
+/*
+ * core.c	power sequence core file
+ *
+ * Copyright (C) 2016 Freescale Semiconductor, Inc.
+ * Author: Peter Chen <peter.chen@....com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2  of
+ * the License as published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/power/pwrseq.h>
+
+static DEFINE_MUTEX(pwrseq_list_mutex);
+static LIST_HEAD(pwrseq_list);
+
+int pwrseq_get(struct device_node *np, struct pwrseq *p)
+{
+	if (p && p->get)
+		return p->get(np, p);
+
+	return -ENOTSUPP;
+}
+EXPORT_SYMBOL_GPL(pwrseq_get);
+
+int pwrseq_on(struct pwrseq *p)
+{
+	if (p && p->on)
+		return p->on(p);
+
+	return -ENOTSUPP;
+}
+EXPORT_SYMBOL_GPL(pwrseq_on);
+
+void pwrseq_off(struct pwrseq *p)
+{
+	if (p && p->off)
+		p->off(p);
+}
+EXPORT_SYMBOL_GPL(pwrseq_off);
+
+void pwrseq_put(struct pwrseq *p)
+{
+	if (p && p->put)
+		p->put(p);
+}
+EXPORT_SYMBOL_GPL(pwrseq_put);
+
+void pwrseq_free(struct pwrseq *p)
+{
+	if (p && p->free)
+		p->free(p);
+}
+EXPORT_SYMBOL_GPL(pwrseq_free);
+
+int pwrseq_suspend(struct pwrseq *p)
+{
+	if (p && p->suspend)
+		return p->suspend(p);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pwrseq_suspend);
+
+int pwrseq_resume(struct pwrseq *p)
+{
+	if (p && p->resume)
+		return p->resume(p);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pwrseq_resume);
+
+void pwrseq_register(struct pwrseq *pwrseq)
+{
+	mutex_lock(&pwrseq_list_mutex);
+	list_add(&pwrseq->node, &pwrseq_list);
+	mutex_unlock(&pwrseq_list_mutex);
+}
+EXPORT_SYMBOL_GPL(pwrseq_register);
+
+static struct pwrseq *pwrseq_find_available_instance(struct device_node *np)
+{
+	struct pwrseq *pwrseq;
+
+	list_for_each_entry(pwrseq, &pwrseq_list, node) {
+		if (pwrseq->used)
+			continue;
+
+		/* compare compatible string for pwrseq node */
+		if (of_match_node(pwrseq->pwrseq_of_match_table, np)) {
+			pwrseq->used = true;
+			return pwrseq;
+		}
+
+		/* return generic pwrseq instance */
+		if (!strcmp(pwrseq->pwrseq_of_match_table->compatible,
+				"generic")) {
+			pr_debug("using generic pwrseq instance for %s\n",
+				np->full_name);
+			pwrseq->used = true;
+			return pwrseq;
+		}
+	}
+	pr_warn("Can't find any pwrseq instances for %s\n", np->full_name);
+
+	return NULL;
+}
+
+struct pwrseq *of_pwrseq_on(struct device_node *np)
+{
+	struct pwrseq *pwrseq;
+	int ret;
+
+	pwrseq = pwrseq_find_available_instance(np);
+	if (!pwrseq)
+		return ERR_PTR(-ENONET);
+
+	ret = pwrseq_get(np, pwrseq);
+	if (ret)
+		goto pwr_free;
+
+	ret = pwrseq_on(pwrseq);
+	if (ret)
+		goto pwr_put;
+
+	return pwrseq;
+
+pwr_put:
+	pwrseq_put(pwrseq);
+pwr_free:
+	pwrseq_free(pwrseq);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(of_pwrseq_on);
+
+void of_pwrseq_off(struct pwrseq *pwrseq)
+{
+	pwrseq_off(pwrseq);
+	pwrseq_put(pwrseq);
+	pwrseq_free(pwrseq);
+}
+EXPORT_SYMBOL_GPL(of_pwrseq_off);
+
+int of_pwrseq_on_list(struct device_node *np, struct list_head *head)
+{
+	struct pwrseq *pwrseq;
+	struct pwrseq_list_per_dev *pwrseq_list_node;
+
+	pwrseq = of_pwrseq_on(np);
+	if (IS_ERR(pwrseq))
+		return PTR_ERR(pwrseq);
+
+	pwrseq_list_node = kzalloc(sizeof(*pwrseq_list_node), GFP_KERNEL);
+	if (!pwrseq_list_node) {
+		of_pwrseq_off(pwrseq);
+		return -ENOMEM;
+	}
+	pwrseq_list_node->pwrseq = pwrseq;
+	list_add(&pwrseq_list_node->list, head);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_pwrseq_on_list);
+
+void of_pwrseq_off_list(struct list_head *head)
+{
+	struct pwrseq *pwrseq;
+	struct pwrseq_list_per_dev *pwrseq_list_node, *tmp_node;
+
+	list_for_each_entry_safe(pwrseq_list_node, tmp_node, head, list) {
+		pwrseq = pwrseq_list_node->pwrseq;
+		of_pwrseq_off(pwrseq);
+		list_del(&pwrseq_list_node->list);
+		kfree(pwrseq_list_node);
+	}
+}
+EXPORT_SYMBOL_GPL(of_pwrseq_off_list);
diff --git a/drivers/power/pwrseq/pwrseq_compatible_sample.c b/drivers/power/pwrseq/pwrseq_compatible_sample.c
new file mode 100644
index 0000000..d6bcc6d
--- /dev/null
+++ b/drivers/power/pwrseq/pwrseq_compatible_sample.c
@@ -0,0 +1,178 @@
+/*
+ * pwrseq_compatible_sample.c	Sample power sequence handling for compatible
+ *
+ * Copyright (C) 2016 Freescale Semiconductor, Inc.
+ * Author: Peter Chen <peter.chen@....com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2  of
+ * the License as published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/slab.h>
+
+#include <linux/power/pwrseq.h>
+
+struct pwrseq_sample {
+	struct pwrseq pwrseq;
+	struct gpio_desc *gpiod_reset;
+	struct clk *clks[PWRSEQ_MAX_CLKS];
+	u32 duration_us;
+};
+
+#define to_generic_pwrseq(p) container_of(p, struct pwrseq_sample, pwrseq)
+
+static void pwrseq_sample_free(struct pwrseq *pwrseq)
+{
+	pwrseq->used = false;
+}
+
+static void pwrseq_sample_put(struct pwrseq *pwrseq)
+{
+	struct pwrseq_sample *pwrseq_sam = to_generic_pwrseq(pwrseq);
+	int clk;
+
+	if (pwrseq_sam->gpiod_reset)
+		gpiod_put(pwrseq_sam->gpiod_reset);
+
+	for (clk = 0; clk < PWRSEQ_MAX_CLKS; clk++)
+		clk_put(pwrseq_sam->clks[clk]);
+}
+
+static void pwrseq_sample_off(struct pwrseq *pwrseq)
+{
+	struct pwrseq_sample *pwrseq_sam = to_generic_pwrseq(pwrseq);
+	int clk;
+
+	for (clk = PWRSEQ_MAX_CLKS - 1; clk >= 0; clk--)
+		clk_disable_unprepare(pwrseq_sam->clks[clk]);
+}
+
+static int pwrseq_sample_on(struct pwrseq *pwrseq)
+{
+	struct pwrseq_sample *pwrseq_sam = to_generic_pwrseq(pwrseq);
+	int clk, ret = 0;
+	struct gpio_desc *gpiod_reset = pwrseq_sam->gpiod_reset;
+
+	for (clk = 0; clk < PWRSEQ_MAX_CLKS && pwrseq_sam->clks[clk]; clk++) {
+		ret = clk_prepare_enable(pwrseq_sam->clks[clk]);
+		if (ret) {
+			pr_err("Can't enable clock, ret=%d\n", ret);
+			goto err_disable_clks;
+		}
+	}
+
+	if (gpiod_reset) {
+		u32 duration_us = pwrseq_sam->duration_us;
+
+		if (duration_us <= 10)
+			udelay(10);
+		else
+			usleep_range(duration_us, duration_us + 100);
+		gpiod_set_value(gpiod_reset, 0);
+	}
+
+	return ret;
+
+err_disable_clks:
+	while (--clk >= 0)
+		clk_disable_unprepare(pwrseq_sam->clks[clk]);
+
+	return ret;
+}
+
+static int pwrseq_sample_get(struct device_node *np, struct pwrseq *pwrseq)
+{
+	struct pwrseq_sample *pwrseq_sam = to_generic_pwrseq(pwrseq);
+	enum of_gpio_flags flags;
+	int reset_gpio, clk, ret = 0;
+
+	for (clk = 0; clk < PWRSEQ_MAX_CLKS; clk++) {
+		pwrseq_sam->clks[clk] = of_clk_get(np, clk);
+		if (IS_ERR(pwrseq_sam->clks[clk])) {
+			ret = PTR_ERR(pwrseq_sam->clks[clk]);
+			if (ret != -ENOENT)
+				goto err_put_clks;
+			pwrseq_sam->clks[clk] = NULL;
+			break;
+		}
+	}
+
+	reset_gpio = of_get_named_gpio_flags(np, "reset-gpios", 0, &flags);
+	if (gpio_is_valid(reset_gpio)) {
+		unsigned long gpio_flags;
+
+		if (flags & OF_GPIO_ACTIVE_LOW)
+			gpio_flags = GPIOF_ACTIVE_LOW | GPIOF_OUT_INIT_LOW;
+		else
+			gpio_flags = GPIOF_OUT_INIT_HIGH;
+
+		ret = gpio_request_one(reset_gpio, gpio_flags,
+				"pwrseq-reset-gpios");
+		if (ret)
+			goto err_put_clks;
+
+		pwrseq_sam->gpiod_reset = gpio_to_desc(reset_gpio);
+		of_property_read_u32(np, "reset-duration-us",
+				&pwrseq_sam->duration_us);
+	} else {
+		if (reset_gpio == -ENOENT)
+			return 0;
+
+		ret = reset_gpio;
+		pr_err("Failed to get reset gpio on %s, err = %d\n",
+				np->full_name, reset_gpio);
+		goto err_put_clks;
+	}
+
+	return ret;
+
+err_put_clks:
+	while (--clk >= 0)
+		clk_put(pwrseq_sam->clks[clk]);
+	return ret;
+}
+
+static const struct of_device_id sample_id_table[] = {
+	{ .compatible = "usb5e3,608",},
+	{ .compatible = "usbb95,1708",},
+	{ /* sentinel */ }
+};
+
+static int __init pwrseq_compatible_sample_register(void)
+{
+	struct pwrseq_sample *pwrseq_sam;
+	int i;
+
+	for (i = 0; i < CONFIG_PWRSEQ_SAMPLE_INSTANCE_NUMBER; i++) {
+		pwrseq_sam = kzalloc(sizeof(*pwrseq_sam), GFP_KERNEL);
+		if (!pwrseq_sam)
+			return -ENOMEM;
+
+		pwrseq_sam->pwrseq.pwrseq_of_match_table = sample_id_table;
+		pwrseq_sam->pwrseq.get = pwrseq_sample_get;
+		pwrseq_sam->pwrseq.on = pwrseq_sample_on;
+		pwrseq_sam->pwrseq.off = pwrseq_sample_off;
+		pwrseq_sam->pwrseq.put = pwrseq_sample_put;
+		pwrseq_sam->pwrseq.free = pwrseq_sample_free;
+
+		pwrseq_register(&pwrseq_sam->pwrseq);
+	}
+
+	return 0;
+}
+postcore_initcall(pwrseq_compatible_sample_register)
diff --git a/drivers/power/pwrseq/pwrseq_generic.c b/drivers/power/pwrseq/pwrseq_generic.c
new file mode 100644
index 0000000..bcd16c3
--- /dev/null
+++ b/drivers/power/pwrseq/pwrseq_generic.c
@@ -0,0 +1,177 @@
+/*
+ * pwrseq_generic.c	Generic power sequence handling
+ *
+ * Copyright (C) 2016 Freescale Semiconductor, Inc.
+ * Author: Peter Chen <peter.chen@....com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2  of
+ * the License as published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/slab.h>
+
+#include <linux/power/pwrseq.h>
+
+struct pwrseq_generic {
+	struct pwrseq pwrseq;
+	struct gpio_desc *gpiod_reset;
+	struct clk *clks[PWRSEQ_MAX_CLKS];
+	u32 duration_us;
+};
+
+#define to_generic_pwrseq(p) container_of(p, struct pwrseq_generic, pwrseq)
+
+static void pwrseq_generic_free(struct pwrseq *pwrseq)
+{
+	pwrseq->used = false;
+}
+
+static void pwrseq_generic_put(struct pwrseq *pwrseq)
+{
+	struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
+	int clk;
+
+	if (pwrseq_gen->gpiod_reset)
+		gpiod_put(pwrseq_gen->gpiod_reset);
+
+	for (clk = 0; clk < PWRSEQ_MAX_CLKS; clk++)
+		clk_put(pwrseq_gen->clks[clk]);
+}
+
+static void pwrseq_generic_off(struct pwrseq *pwrseq)
+{
+	struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
+	int clk;
+
+	for (clk = PWRSEQ_MAX_CLKS - 1; clk >= 0; clk--)
+		clk_disable_unprepare(pwrseq_gen->clks[clk]);
+}
+
+static int pwrseq_generic_on(struct pwrseq *pwrseq)
+{
+	struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
+	int clk, ret = 0;
+	struct gpio_desc *gpiod_reset = pwrseq_gen->gpiod_reset;
+
+	for (clk = 0; clk < PWRSEQ_MAX_CLKS && pwrseq_gen->clks[clk]; clk++) {
+		ret = clk_prepare_enable(pwrseq_gen->clks[clk]);
+		if (ret) {
+			pr_err("Can't enable clock, ret=%d\n", ret);
+			goto err_disable_clks;
+		}
+	}
+
+	if (gpiod_reset) {
+		u32 duration_us = pwrseq_gen->duration_us;
+
+		if (duration_us <= 10)
+			udelay(10);
+		else
+			usleep_range(duration_us, duration_us + 100);
+		gpiod_set_value(gpiod_reset, 0);
+	}
+
+	return ret;
+
+err_disable_clks:
+	while (--clk >= 0)
+		clk_disable_unprepare(pwrseq_gen->clks[clk]);
+
+	return ret;
+}
+
+static int pwrseq_generic_get(struct device_node *np, struct pwrseq *pwrseq)
+{
+	struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
+	enum of_gpio_flags flags;
+	int reset_gpio, clk, ret = 0;
+
+	for (clk = 0; clk < PWRSEQ_MAX_CLKS; clk++) {
+		pwrseq_gen->clks[clk] = of_clk_get(np, clk);
+		if (IS_ERR(pwrseq_gen->clks[clk])) {
+			ret = PTR_ERR(pwrseq_gen->clks[clk]);
+			if (ret != -ENOENT)
+				goto err_put_clks;
+			pwrseq_gen->clks[clk] = NULL;
+			break;
+		}
+	}
+
+	reset_gpio = of_get_named_gpio_flags(np, "reset-gpios", 0, &flags);
+	if (gpio_is_valid(reset_gpio)) {
+		unsigned long gpio_flags;
+
+		if (flags & OF_GPIO_ACTIVE_LOW)
+			gpio_flags = GPIOF_ACTIVE_LOW | GPIOF_OUT_INIT_LOW;
+		else
+			gpio_flags = GPIOF_OUT_INIT_HIGH;
+
+		ret = gpio_request_one(reset_gpio, gpio_flags,
+				"pwrseq-reset-gpios");
+		if (ret)
+			goto err_put_clks;
+
+		pwrseq_gen->gpiod_reset = gpio_to_desc(reset_gpio);
+		of_property_read_u32(np, "reset-duration-us",
+				&pwrseq_gen->duration_us);
+	} else {
+		if (reset_gpio == -ENOENT)
+			return 0;
+
+		ret = reset_gpio;
+		pr_err("Failed to get reset gpio on %s, err = %d\n",
+				np->full_name, reset_gpio);
+		goto err_put_clks;
+	}
+
+	return ret;
+
+err_put_clks:
+	while (--clk >= 0)
+		clk_put(pwrseq_gen->clks[clk]);
+	return ret;
+}
+
+static const struct of_device_id generic_id_table[] = {
+	{ .compatible = "generic",},
+	{ /* sentinel */ }
+};
+
+static int __init pwrseq_generic_register(void)
+{
+	struct pwrseq_generic *pwrseq_gen;
+	int i;
+
+	for (i = 0; i < CONFIG_PWRSEQ_GENERIC_INSTANCE_NUMBER; i++) {
+		pwrseq_gen = kzalloc(sizeof(*pwrseq_gen), GFP_KERNEL);
+		if (!pwrseq_gen)
+			return -ENOMEM;
+
+		pwrseq_gen->pwrseq.pwrseq_of_match_table = generic_id_table;
+		pwrseq_gen->pwrseq.get = pwrseq_generic_get;
+		pwrseq_gen->pwrseq.on = pwrseq_generic_on;
+		pwrseq_gen->pwrseq.off = pwrseq_generic_off;
+		pwrseq_gen->pwrseq.put = pwrseq_generic_put;
+		pwrseq_gen->pwrseq.free = pwrseq_generic_free;
+
+		pwrseq_register(&pwrseq_gen->pwrseq);
+	}
+
+	return 0;
+}
+postcore_initcall(pwrseq_generic_register)
diff --git a/include/linux/power/pwrseq.h b/include/linux/power/pwrseq.h
new file mode 100644
index 0000000..ae4753f
--- /dev/null
+++ b/include/linux/power/pwrseq.h
@@ -0,0 +1,73 @@
+#ifndef __LINUX_PWRSEQ_H
+#define __LINUX_PWRSEQ_H
+
+#include <linux/of.h>
+
+#define PWRSEQ_MAX_CLKS		3
+
+struct pwrseq {
+	const struct of_device_id *pwrseq_of_match_table;
+	struct list_head node;
+	int (*get)(struct device_node *np, struct pwrseq *p);
+	int (*on)(struct pwrseq *p);
+	void (*off)(struct pwrseq *p);
+	void (*put)(struct pwrseq *p);
+	void (*free)(struct pwrseq *p);
+	int (*suspend)(struct pwrseq *p);
+	int (*resume)(struct pwrseq *p);
+	bool used;
+};
+
+/* used for power sequence instance list in one driver */
+struct pwrseq_list_per_dev {
+	struct pwrseq *pwrseq;
+	struct list_head list;
+};
+
+#if IS_ENABLED(CONFIG_POWER_SEQUENCE)
+int pwrseq_get(struct device_node *np, struct pwrseq *p);
+int pwrseq_on(struct pwrseq *p);
+void pwrseq_off(struct pwrseq *p);
+void pwrseq_put(struct pwrseq *p);
+void pwrseq_free(struct pwrseq *p);
+int pwrseq_suspend(struct pwrseq *p);
+int pwrseq_resume(struct pwrseq *p);
+void pwrseq_register(struct pwrseq *pwrseq);
+struct pwrseq *of_pwrseq_on(struct device_node *np);
+void of_pwrseq_off(struct pwrseq *pwrseq);
+int of_pwrseq_on_list(struct device_node *np, struct list_head *head);
+void of_pwrseq_off_list(struct list_head *head);
+#else
+static inline int pwrseq_get(struct device_node *np, struct pwrseq *p)
+{
+	return 0;
+}
+static inline int pwrseq_on(struct pwrseq *p)
+{
+	return 0;
+}
+static inline void pwrseq_off(struct pwrseq *p) {}
+static inline void pwrseq_put(struct pwrseq *p) {}
+static inline void pwrseq_free(struct pwrseq *p) {}
+static inline int pwrseq_suspend(struct pwrseq *p)
+{
+	return 0;
+}
+static inline int pwrseq_resume(struct pwrseq *p)
+{
+	return 0;
+}
+static inline void pwrseq_register(struct pwrseq *pwrseq) {}
+static inline struct pwrseq *of_pwrseq_on(struct device_node *np)
+{
+	return NULL;
+}
+void of_pwrseq_off(struct pwrseq *pwrseq) {}
+int of_pwrseq_on_list(struct device_node *np, struct list_head *head)
+{
+	return 0;
+}
+void of_pwrseq_off_list(struct list_head *head) {}
+#endif /* CONFIG_POWER_SEQUENCE */
+
+#endif  /* __LINUX_PWRSEQ_H */
-- 
2.7.4

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