[PATCH v3 1/2] Documentation: Add GPIO reset binding to reset binding documentation

[PATCH v3 1/2] Documentation: Add GPIO reset binding to reset binding documentation

[Philipp Zabel]

This patch adds documentation clarifying the reset GPIO bindings most
commonly in use (reset-gpios and <name>-reset-gpios properties).

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 Documentation/devicetree/bindings/reset/reset.txt | 26 +++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/reset/reset.txt b/Documentation/devicetree/bindings/reset/reset.txt
index 31db6ff..51f9e35 100644
--- a/Documentation/devicetree/bindings/reset/reset.txt
+++ b/Documentation/devicetree/bindings/reset/reset.txt
@@ -2,8 +2,8 @@
 
 This binding is intended to represent the hardware reset signals present
 internally in most IC (SoC, FPGA, ...) designs. Reset signals for whole
-standalone chips are most likely better represented as GPIOs, although there
-are likely to be exceptions to this rule.
+standalone chips are most likely better represented as GPIOs, ideally using a
+common scheme as described below.
 
 Hardware blocks typically receive a reset signal. This signal is generated by
 a reset provider (e.g. power management or clock module) and received by a
@@ -56,6 +56,20 @@ reset-names:	List of reset signal name strings sorted in the same order as
 		the resets property. Consumers drivers will use reset-names to
 		match reset signal names with reset specifiers.
 
+= GPIO Reset consumers =
+
+For the common case of reset lines controlled by GPIOs, the GPIO binding
+documented in devicetree/bindings/gpio/gpio.txt should be used:
+
+Required properties:
+reset-gpios or		Reset GPIO using standard GPIO bindings,
+<name>-reset-gpios:	optionally named to specify the reset line
+
+Optional properties:
+reset-boot-asserted or		Boolean. If set, the corresponding reset is
+<name>-reset-boot-asserted:	initially asserted and should be kept that way
+				until released by the driver.
+
 For example:
 
 	device {
@@ -65,6 +79,14 @@ For example:
 
 This represents a device with a single reset signal named "reset".
 
+	device2 {
+		reset-gpios = <&gpio3 15 GPIO_ACTIVE_LOW>;
+		reset-boot-asserted;
+	};
+
+This represents a device with a single reset signal, controlled
+by an active-low GPIO, which is initally kept in reset.
+
 	bus {
 		resets = <&rst 10> <&rst 11> <&rst 12> <&rst 11>;
 		reset-names = "i2s1", "i2s2", "dma", "mixer";
-- 
1.8.5.2

[PATCH v3 1/2] Documentation: Add GPIO reset binding to reset binding documentation

[Philipp Zabel]

This patch adds documentation clarifying the reset GPIO bindings most
commonly in use (reset-gpios and <name>-reset-gpios properties).

Signed-off-by: Philipp Zabel <p.zabel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
---
 Documentation/devicetree/bindings/reset/reset.txt | 26 +++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/reset/reset.txt b/Documentation/devicetree/bindings/reset/reset.txt
index 31db6ff..51f9e35 100644
--- a/Documentation/devicetree/bindings/reset/reset.txt
+++ b/Documentation/devicetree/bindings/reset/reset.txt
@@ -2,8 +2,8 @@
 
 This binding is intended to represent the hardware reset signals present
 internally in most IC (SoC, FPGA, ...) designs. Reset signals for whole
-standalone chips are most likely better represented as GPIOs, although there
-are likely to be exceptions to this rule.
+standalone chips are most likely better represented as GPIOs, ideally using a
+common scheme as described below.
 
 Hardware blocks typically receive a reset signal. This signal is generated by
 a reset provider (e.g. power management or clock module) and received by a
@@ -56,6 +56,20 @@ reset-names:	List of reset signal name strings sorted in the same order as
 		the resets property. Consumers drivers will use reset-names to
 		match reset signal names with reset specifiers.
 
+= GPIO Reset consumers =
+
+For the common case of reset lines controlled by GPIOs, the GPIO binding
+documented in devicetree/bindings/gpio/gpio.txt should be used:
+
+Required properties:
+reset-gpios or		Reset GPIO using standard GPIO bindings,
+<name>-reset-gpios:	optionally named to specify the reset line
+
+Optional properties:
+reset-boot-asserted or		Boolean. If set, the corresponding reset is
+<name>-reset-boot-asserted:	initially asserted and should be kept that way
+				until released by the driver.
+
 For example:
 
 	device {
@@ -65,6 +79,14 @@ For example:
 
 This represents a device with a single reset signal named "reset".
 
+	device2 {
+		reset-gpios = <&gpio3 15 GPIO_ACTIVE_LOW>;
+		reset-boot-asserted;
+	};
+
+This represents a device with a single reset signal, controlled
+by an active-low GPIO, which is initally kept in reset.
+
 	bus {
 		resets = <&rst 10> <&rst 11> <&rst 12> <&rst 11>;
 		reset-names = "i2s1", "i2s2", "dma", "mixer";
-- 
1.8.5.2

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[PATCH v3 2/2] reset: Add GPIO support to reset controller framework

[Philipp Zabel]

This adds support for GPIO controlled reset pins on peripheral ICs to the reset
controller framework. Currently there is no support for specifying a delay
between assertion and de-assertion of the reset signal, so this has to be
handled by the drivers.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
Changes since v2:
 - fix assert_prop initial value
---
 drivers/reset/Kconfig      |  17 ++++++
 drivers/reset/Makefile     |   9 ++-
 drivers/reset/core.c       |  29 +++++-----
 drivers/reset/gpio-reset.c | 137 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/reset/reset-core.h |  47 ++++++++++++++++
 5 files changed, 224 insertions(+), 15 deletions(-)
 create mode 100644 drivers/reset/gpio-reset.c
 create mode 100644 drivers/reset/reset-core.h

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index c9d04f7..a6b12a9 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -10,4 +10,21 @@ menuconfig RESET_CONTROLLER
 	  This framework is designed to abstract reset handling of devices
 	  via GPIOs or SoC-internal reset controller modules.
 
+	  If the device tree contains any resets or reset-gpio properties,
+	  this probably should be enabled.
+
 	  If unsure, say no.
+
+if RESET_CONTROLLER
+
+menuconfig RESET_GPIO
+	bool "GPIO Reset Support"
+	depends on GPIOLIB
+	default y if GPIOLIB
+	help
+	  GPIO Reset Controller support.
+
+	  This option lets the reset controller framework handle reset lines
+	  connected to GPIOs.
+
+endif
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index cc29832..764bb74 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -1,2 +1,9 @@
-obj-$(CONFIG_RESET_CONTROLLER) += core.o
+reset-core-objs := core.o
+
+obj-$(CONFIG_RESET_CONTROLLER) += reset-core.o
+
+ifeq ($(CONFIG_RESET_GPIO),y)
+  reset-core-objs += gpio-reset.o
+endif
+
 obj-$(CONFIG_ARCH_SUNXI) += reset-sunxi.o
diff --git a/drivers/reset/core.c b/drivers/reset/core.c
index baeaf82..6bfd2d2 100644
--- a/drivers/reset/core.c
+++ b/drivers/reset/core.c
@@ -18,23 +18,12 @@
 #include <linux/reset-controller.h>
 #include <linux/slab.h>
 
+#include "reset-core.h"
+
 static DEFINE_MUTEX(reset_controller_list_mutex);
 static LIST_HEAD(reset_controller_list);
 
 /**
- * struct reset_control - a reset control
- * @rcdev: a pointer to the reset controller device
- *         this reset control belongs to
- * @id: ID of the reset controller in the reset
- *      controller device
- */
-struct reset_control {
-	struct reset_controller_dev *rcdev;
-	struct device *dev;
-	unsigned int id;
-};
-
-/**
  * of_reset_simple_xlate - translate reset_spec to the reset line number
  * @rcdev: a pointer to the reset controller device
  * @reset_spec: reset line specifier as found in the device tree
@@ -149,6 +138,8 @@ struct reset_control *of_reset_control_get(struct device_node *node,
 						 "reset-names", id);
 	ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
 					 index, &args);
+	if (index == -EINVAL)
+		return ERR_PTR(-ENOENT);
 	if (ret)
 		return ERR_PTR(ret);
 
@@ -209,6 +200,13 @@ struct reset_control *reset_control_get(struct device *dev, const char *id)
 	if (!IS_ERR(rstc))
 		rstc->dev = dev;
 
+	/*
+	 * If there is no dedicated reset controller device, check if we have
+	 * a reset line controlled by a GPIO instead.
+	 */
+	if (PTR_ERR(rstc) == -ENOENT)
+		return gpio_reset_control_get(dev, id);
+
 	return rstc;
 }
 EXPORT_SYMBOL_GPL(reset_control_get);
@@ -223,7 +221,10 @@ void reset_control_put(struct reset_control *rstc)
 	if (IS_ERR(rstc))
 		return;
 
-	module_put(rstc->rcdev->owner);
+	if (reset_control_is_gpio(rstc))
+		gpio_reset_control_put(rstc);
+	else
+		module_put(rstc->rcdev->owner);
 	kfree(rstc);
 }
 EXPORT_SYMBOL_GPL(reset_control_put);
diff --git a/drivers/reset/gpio-reset.c b/drivers/reset/gpio-reset.c
new file mode 100644
index 0000000..77d4bd7
--- /dev/null
+++ b/drivers/reset/gpio-reset.c
@@ -0,0 +1,137 @@
+/*
+ * GPIO Reset Controller
+ *
+ * Copyright 2013 Philipp Zabel, Pengutronix
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
+#include <linux/reset-controller.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include "reset-core.h"
+
+/*
+ * Global GPIO reset controller
+ */
+static struct reset_controller_dev *gpio_rcdev;
+
+static int gpio_reset_set(struct reset_controller_dev *rcdev,
+			  unsigned int gpio, int asserted)
+{
+	struct gpio_desc *gpiod = gpio_to_desc(gpio);
+
+	if (!gpiod)
+		return -EINVAL;
+
+	gpiod_set_value_cansleep(gpiod, asserted);
+
+	return 0;
+}
+
+static int gpio_reset_assert(struct reset_controller_dev *rcdev,
+		unsigned long id)
+{
+	return gpio_reset_set(rcdev, id, 1);
+}
+
+static int gpio_reset_deassert(struct reset_controller_dev *rcdev,
+		unsigned long id)
+{
+	return gpio_reset_set(rcdev, id, 0);
+}
+
+static struct reset_control_ops gpio_reset_ops = {
+	.assert = gpio_reset_assert,
+	.deassert = gpio_reset_deassert,
+};
+
+struct reset_controller_dev *reset_get_gpio_rcdev(void)
+{
+	if (gpio_rcdev)
+		return gpio_rcdev;
+
+	gpio_rcdev = kzalloc(sizeof(*gpio_rcdev), GFP_KERNEL);
+	if (!gpio_rcdev)
+		return NULL;
+
+	gpio_rcdev->owner = THIS_MODULE;
+	gpio_rcdev->ops = &gpio_reset_ops;
+
+	reset_controller_register(gpio_rcdev);
+
+	return gpio_rcdev;
+}
+
+struct reset_control *gpio_reset_control_get(struct device *dev, const char *id)
+{
+	const char *assert_prop = "reset-boot-asserted";
+	const char *gpio_con_id = "reset";
+	struct reset_controller_dev *rcdev;
+	struct reset_control *rstc;
+	struct gpio_desc *gpiod;
+	char scratch[48];
+	bool asserted;
+	int ret;
+
+	if (id) {
+		snprintf(scratch, 48, "%s-reset-boot-asserted", id);
+		assert_prop = scratch;
+	}
+
+	asserted = of_property_read_bool(dev->of_node, assert_prop);
+
+	if (id) {
+		snprintf(scratch, 48, "%s-reset", id);
+		gpio_con_id = scratch;
+	}
+
+	gpiod = gpiod_get(dev, gpio_con_id);
+	if (IS_ERR(gpiod)) {
+		dev_err(dev, "Failed to get GPIO reset: %ld\n", PTR_ERR(gpiod));
+		return ERR_CAST(gpiod);
+	}
+
+	ret = gpiod_direction_output(gpiod, asserted);
+	if (ret < 0)
+		goto err_put;
+
+	ret = -ENOMEM;
+	rcdev = reset_get_gpio_rcdev();
+	if (!rcdev)
+		goto err_put;
+
+	rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
+	if (!rstc)
+		goto err_put;
+
+	rstc->dev = dev;
+	rstc->rcdev = rcdev;
+	rstc->id = desc_to_gpio(gpiod);
+
+	return rstc;
+
+err_put:
+	gpiod_put(gpiod);
+	return ERR_PTR(ret);
+}
+
+bool reset_control_is_gpio(struct reset_control *rstc)
+{
+	return rstc->rcdev == gpio_rcdev;
+}
+
+void gpio_reset_control_put(struct reset_control *rstc)
+{
+	struct gpio_desc *gpiod = gpio_to_desc(rstc->id);
+
+	if (gpiod)
+		gpiod_put(gpiod);
+}
diff --git a/drivers/reset/reset-core.h b/drivers/reset/reset-core.h
new file mode 100644
index 0000000..55bd297
--- /dev/null
+++ b/drivers/reset/reset-core.h
@@ -0,0 +1,47 @@
+/*
+ * Reset Controller framework
+ *
+ * Copyright 2013 Philipp Zabel, Pengutronix
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef __RESET_CORE_H__
+#define __RESET_CORE_H__
+
+/**
+ * struct reset_control - a reset control
+ * @rcdev: a pointer to the reset controller device
+ *         this reset control belongs to
+ * @id: ID of the reset controller in the reset
+ *      controller device
+ */
+struct reset_control {
+	struct reset_controller_dev *rcdev;
+	struct device *dev;
+	unsigned int id;
+};
+
+#if IS_ENABLED(CONFIG_RESET_GPIO)
+struct reset_control *gpio_reset_control_get(struct device *dev, const char *id);
+bool reset_control_is_gpio(struct reset_control *rstc);
+void gpio_reset_control_put(struct reset_control *rstc);
+#else
+static inline struct reset_control *gpio_reset_control_get(struct device *dev,
+						    const char *id)
+{
+	return -ENOSYS;
+}
+
+static inline bool reset_control_is_gpio(struct reset_control *rstc)
+{
+	return false;
+}
+
+static inline void gpio_reset_control_put(struct reset_control *rstc) { }
+#endif
+
+#endif
-- 
1.8.5.2

[PATCH v3 2/2] reset: Add GPIO support to reset controller framework

[Philipp Zabel]

This adds support for GPIO controlled reset pins on peripheral ICs to the reset
controller framework. Currently there is no support for specifying a delay
between assertion and de-assertion of the reset signal, so this has to be
handled by the drivers.

Signed-off-by: Philipp Zabel <p.zabel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
---
Changes since v2:
 - fix assert_prop initial value
---
 drivers/reset/Kconfig      |  17 ++++++
 drivers/reset/Makefile     |   9 ++-
 drivers/reset/core.c       |  29 +++++-----
 drivers/reset/gpio-reset.c | 137 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/reset/reset-core.h |  47 ++++++++++++++++
 5 files changed, 224 insertions(+), 15 deletions(-)
 create mode 100644 drivers/reset/gpio-reset.c
 create mode 100644 drivers/reset/reset-core.h

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index c9d04f7..a6b12a9 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -10,4 +10,21 @@ menuconfig RESET_CONTROLLER
 	  This framework is designed to abstract reset handling of devices
 	  via GPIOs or SoC-internal reset controller modules.
 
+	  If the device tree contains any resets or reset-gpio properties,
+	  this probably should be enabled.
+
 	  If unsure, say no.
+
+if RESET_CONTROLLER
+
+menuconfig RESET_GPIO
+	bool "GPIO Reset Support"
+	depends on GPIOLIB
+	default y if GPIOLIB
+	help
+	  GPIO Reset Controller support.
+
+	  This option lets the reset controller framework handle reset lines
+	  connected to GPIOs.
+
+endif
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index cc29832..764bb74 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -1,2 +1,9 @@
-obj-$(CONFIG_RESET_CONTROLLER) += core.o
+reset-core-objs := core.o
+
+obj-$(CONFIG_RESET_CONTROLLER) += reset-core.o
+
+ifeq ($(CONFIG_RESET_GPIO),y)
+  reset-core-objs += gpio-reset.o
+endif
+
 obj-$(CONFIG_ARCH_SUNXI) += reset-sunxi.o
diff --git a/drivers/reset/core.c b/drivers/reset/core.c
index baeaf82..6bfd2d2 100644
--- a/drivers/reset/core.c
+++ b/drivers/reset/core.c
@@ -18,23 +18,12 @@
 #include <linux/reset-controller.h>
 #include <linux/slab.h>
 
+#include "reset-core.h"
+
 static DEFINE_MUTEX(reset_controller_list_mutex);
 static LIST_HEAD(reset_controller_list);
 
 /**
- * struct reset_control - a reset control
- * @rcdev: a pointer to the reset controller device
- *         this reset control belongs to
- * @id: ID of the reset controller in the reset
- *      controller device
- */
-struct reset_control {
-	struct reset_controller_dev *rcdev;
-	struct device *dev;
-	unsigned int id;
-};
-
-/**
  * of_reset_simple_xlate - translate reset_spec to the reset line number
  * @rcdev: a pointer to the reset controller device
  * @reset_spec: reset line specifier as found in the device tree
@@ -149,6 +138,8 @@ struct reset_control *of_reset_control_get(struct device_node *node,
 						 "reset-names", id);
 	ret = of_parse_phandle_with_args(node, "resets", "#reset-cells",
 					 index, &args);
+	if (index == -EINVAL)
+		return ERR_PTR(-ENOENT);
 	if (ret)
 		return ERR_PTR(ret);
 
@@ -209,6 +200,13 @@ struct reset_control *reset_control_get(struct device *dev, const char *id)
 	if (!IS_ERR(rstc))
 		rstc->dev = dev;
 
+	/*
+	 * If there is no dedicated reset controller device, check if we have
+	 * a reset line controlled by a GPIO instead.
+	 */
+	if (PTR_ERR(rstc) == -ENOENT)
+		return gpio_reset_control_get(dev, id);
+
 	return rstc;
 }
 EXPORT_SYMBOL_GPL(reset_control_get);
@@ -223,7 +221,10 @@ void reset_control_put(struct reset_control *rstc)
 	if (IS_ERR(rstc))
 		return;
 
-	module_put(rstc->rcdev->owner);
+	if (reset_control_is_gpio(rstc))
+		gpio_reset_control_put(rstc);
+	else
+		module_put(rstc->rcdev->owner);
 	kfree(rstc);
 }
 EXPORT_SYMBOL_GPL(reset_control_put);
diff --git a/drivers/reset/gpio-reset.c b/drivers/reset/gpio-reset.c
new file mode 100644
index 0000000..77d4bd7
--- /dev/null
+++ b/drivers/reset/gpio-reset.c
@@ -0,0 +1,137 @@
+/*
+ * GPIO Reset Controller
+ *
+ * Copyright 2013 Philipp Zabel, Pengutronix
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
+#include <linux/reset-controller.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include "reset-core.h"
+
+/*
+ * Global GPIO reset controller
+ */
+static struct reset_controller_dev *gpio_rcdev;
+
+static int gpio_reset_set(struct reset_controller_dev *rcdev,
+			  unsigned int gpio, int asserted)
+{
+	struct gpio_desc *gpiod = gpio_to_desc(gpio);
+
+	if (!gpiod)
+		return -EINVAL;
+
+	gpiod_set_value_cansleep(gpiod, asserted);
+
+	return 0;
+}
+
+static int gpio_reset_assert(struct reset_controller_dev *rcdev,
+		unsigned long id)
+{
+	return gpio_reset_set(rcdev, id, 1);
+}
+
+static int gpio_reset_deassert(struct reset_controller_dev *rcdev,
+		unsigned long id)
+{
+	return gpio_reset_set(rcdev, id, 0);
+}
+
+static struct reset_control_ops gpio_reset_ops = {
+	.assert = gpio_reset_assert,
+	.deassert = gpio_reset_deassert,
+};
+
+struct reset_controller_dev *reset_get_gpio_rcdev(void)
+{
+	if (gpio_rcdev)
+		return gpio_rcdev;
+
+	gpio_rcdev = kzalloc(sizeof(*gpio_rcdev), GFP_KERNEL);
+	if (!gpio_rcdev)
+		return NULL;
+
+	gpio_rcdev->owner = THIS_MODULE;
+	gpio_rcdev->ops = &gpio_reset_ops;
+
+	reset_controller_register(gpio_rcdev);
+
+	return gpio_rcdev;
+}
+
+struct reset_control *gpio_reset_control_get(struct device *dev, const char *id)
+{
+	const char *assert_prop = "reset-boot-asserted";
+	const char *gpio_con_id = "reset";
+	struct reset_controller_dev *rcdev;
+	struct reset_control *rstc;
+	struct gpio_desc *gpiod;
+	char scratch[48];
+	bool asserted;
+	int ret;
+
+	if (id) {
+		snprintf(scratch, 48, "%s-reset-boot-asserted", id);
+		assert_prop = scratch;
+	}
+
+	asserted = of_property_read_bool(dev->of_node, assert_prop);
+
+	if (id) {
+		snprintf(scratch, 48, "%s-reset", id);
+		gpio_con_id = scratch;
+	}
+
+	gpiod = gpiod_get(dev, gpio_con_id);
+	if (IS_ERR(gpiod)) {
+		dev_err(dev, "Failed to get GPIO reset: %ld\n", PTR_ERR(gpiod));
+		return ERR_CAST(gpiod);
+	}
+
+	ret = gpiod_direction_output(gpiod, asserted);
+	if (ret < 0)
+		goto err_put;
+
+	ret = -ENOMEM;
+	rcdev = reset_get_gpio_rcdev();
+	if (!rcdev)
+		goto err_put;
+
+	rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
+	if (!rstc)
+		goto err_put;
+
+	rstc->dev = dev;
+	rstc->rcdev = rcdev;
+	rstc->id = desc_to_gpio(gpiod);
+
+	return rstc;
+
+err_put:
+	gpiod_put(gpiod);
+	return ERR_PTR(ret);
+}
+
+bool reset_control_is_gpio(struct reset_control *rstc)
+{
+	return rstc->rcdev == gpio_rcdev;
+}
+
+void gpio_reset_control_put(struct reset_control *rstc)
+{
+	struct gpio_desc *gpiod = gpio_to_desc(rstc->id);
+
+	if (gpiod)
+		gpiod_put(gpiod);
+}
diff --git a/drivers/reset/reset-core.h b/drivers/reset/reset-core.h
new file mode 100644
index 0000000..55bd297
--- /dev/null
+++ b/drivers/reset/reset-core.h
@@ -0,0 +1,47 @@
+/*
+ * Reset Controller framework
+ *
+ * Copyright 2013 Philipp Zabel, Pengutronix
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef __RESET_CORE_H__
+#define __RESET_CORE_H__
+
+/**
+ * struct reset_control - a reset control
+ * @rcdev: a pointer to the reset controller device
+ *         this reset control belongs to
+ * @id: ID of the reset controller in the reset
+ *      controller device
+ */
+struct reset_control {
+	struct reset_controller_dev *rcdev;
+	struct device *dev;
+	unsigned int id;
+};
+
+#if IS_ENABLED(CONFIG_RESET_GPIO)
+struct reset_control *gpio_reset_control_get(struct device *dev, const char *id);
+bool reset_control_is_gpio(struct reset_control *rstc);
+void gpio_reset_control_put(struct reset_control *rstc);
+#else
+static inline struct reset_control *gpio_reset_control_get(struct device *dev,
+						    const char *id)
+{
+	return -ENOSYS;
+}
+
+static inline bool reset_control_is_gpio(struct reset_control *rstc)
+{
+	return false;
+}
+
+static inline void gpio_reset_control_put(struct reset_control *rstc) { }
+#endif
+
+#endif
-- 
1.8.5.2

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Re: [PATCH v3 1/2] Documentation: Add GPIO reset binding to reset binding documentation

[Arnd Bergmann]

On Wednesday 08 January 2014, Philipp Zabel wrote:
> += GPIO Reset consumers =
> +
> +For the common case of reset lines controlled by GPIOs, the GPIO binding
> +documented in devicetree/bindings/gpio/gpio.txt should be used:
> +
> +Required properties:
> +reset-gpios or         Reset GPIO using standard GPIO bindings,
> +<name>-reset-gpios:    optionally named to specify the reset line
> +
> +Optional properties:
> +reset-boot-asserted or         Boolean. If set, the corresponding reset is
> +<name>-reset-boot-asserted:    initially asserted and should be kept that way
> +                               until released by the driver.

I don't get this one. Why would you use a different reset binding for the case
where the reset line is connected to the gpio controller rather than a
specialized reset controller?

I was expecting to see the definition of a generic reset controller that
in turn uses gpio lines, like


	reset {	
		compatible = "gpio-reset";
		/* provides three reset lines through these GPIOs */
		gpios = <&gpioA 1 &gpioB 7 <gpioD 17>;
		#reset-cells = <1>;
	};

	foo {
		...
		resets = <&reset 0>; /* uses first reset line of the gpio-reset controller */
	};

I realize it would be a little more verbose, but it also seems more
regular and wouldn't stand out from the rest of the reset interfaces.

	Arnd

Re: [PATCH v3 1/2] Documentation: Add GPIO reset binding to reset binding documentation

[Arnd Bergmann]

On Wednesday 08 January 2014, Philipp Zabel wrote:
> += GPIO Reset consumers =
> +
> +For the common case of reset lines controlled by GPIOs, the GPIO binding
> +documented in devicetree/bindings/gpio/gpio.txt should be used:
> +
> +Required properties:
> +reset-gpios or         Reset GPIO using standard GPIO bindings,
> +<name>-reset-gpios:    optionally named to specify the reset line
> +
> +Optional properties:
> +reset-boot-asserted or         Boolean. If set, the corresponding reset is
> +<name>-reset-boot-asserted:    initially asserted and should be kept that way
> +                               until released by the driver.

I don't get this one. Why would you use a different reset binding for the case
where the reset line is connected to the gpio controller rather than a
specialized reset controller?

I was expecting to see the definition of a generic reset controller that
in turn uses gpio lines, like


	reset {	
		compatible = "gpio-reset";
		/* provides three reset lines through these GPIOs */
		gpios = <&gpioA 1 &gpioB 7 <gpioD 17>;
		#reset-cells = <1>;
	};

	foo {
		...
		resets = <&reset 0>; /* uses first reset line of the gpio-reset controller */
	};

I realize it would be a little more verbose, but it also seems more
regular and wouldn't stand out from the rest of the reset interfaces.

	Arnd
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Re: [PATCH v3 1/2] Documentation: Add GPIO reset binding to reset binding documentation

[Philipp Zabel]

Hi Arnd,

Am Mittwoch, den 08.01.2014, 17:08 +0100 schrieb Arnd Bergmann:
> On Wednesday 08 January 2014, Philipp Zabel wrote:
> > += GPIO Reset consumers =
> > +
> > +For the common case of reset lines controlled by GPIOs, the GPIO binding
> > +documented in devicetree/bindings/gpio/gpio.txt should be used:
> > +
> > +Required properties:
> > +reset-gpios or         Reset GPIO using standard GPIO bindings,
> > +<name>-reset-gpios:    optionally named to specify the reset line
> > +
> > +Optional properties:
> > +reset-boot-asserted or         Boolean. If set, the corresponding reset is
> > +<name>-reset-boot-asserted:    initially asserted and should be kept that way
> > +                               until released by the driver.
> 
> I don't get this one. Why would you use a different reset binding for the case
> where the reset line is connected to the gpio controller rather than a
> specialized reset controller?
> 
> I was expecting to see the definition of a generic reset controller that
> in turn uses gpio lines, like
> 
> 
>         reset { 
>                 compatible = "gpio-reset";
>                 /* provides three reset lines through these GPIOs */
>                 gpios = <&gpioA 1 &gpioB 7 <gpioD 17>;
>                 #reset-cells = <1>;
>         };
> 
>         foo {
>                 ...
>                 resets = <&reset 0>; /* uses first reset line of the gpio-reset controller */
>         };

That is what I initially proposed...

> I realize it would be a little more verbose, but it also seems more
> regular and wouldn't stand out from the rest of the reset interfaces.

... but it can also be argued that GPIO resets shouldn't stand out from
other GPIOs.

Mark Rutland spoke out against having a 'GPIO reset device' node in the
device tree:

http://comments.gmane.org/gmane.linux.drivers.devicetree/41596

and I see his point. Using different bindings for reset controller IPs
and for single GPIOs better describes the actual hardware and it is less
Linux specific: it still allows an OS without gpio-reset framework to
let each driver handle the GPIO itself.

Also Stephen Warren pointed out that we'll have to support the existing
GPIO bindings anyway: in the meantime there are a lot of GPIO resets in
various device trees that use the GPIO bindings.

regards
Philipp

Re: [PATCH v3 1/2] Documentation: Add GPIO reset binding to reset binding documentation

[Philipp Zabel]

Hi Arnd,

Am Mittwoch, den 08.01.2014, 17:08 +0100 schrieb Arnd Bergmann:
> On Wednesday 08 January 2014, Philipp Zabel wrote:
> > += GPIO Reset consumers =
> > +
> > +For the common case of reset lines controlled by GPIOs, the GPIO binding
> > +documented in devicetree/bindings/gpio/gpio.txt should be used:
> > +
> > +Required properties:
> > +reset-gpios or         Reset GPIO using standard GPIO bindings,
> > +<name>-reset-gpios:    optionally named to specify the reset line
> > +
> > +Optional properties:
> > +reset-boot-asserted or         Boolean. If set, the corresponding reset is
> > +<name>-reset-boot-asserted:    initially asserted and should be kept that way
> > +                               until released by the driver.
> 
> I don't get this one. Why would you use a different reset binding for the case
> where the reset line is connected to the gpio controller rather than a
> specialized reset controller?
> 
> I was expecting to see the definition of a generic reset controller that
> in turn uses gpio lines, like
> 
> 
>         reset { 
>                 compatible = "gpio-reset";
>                 /* provides three reset lines through these GPIOs */
>                 gpios = <&gpioA 1 &gpioB 7 <gpioD 17>;
>                 #reset-cells = <1>;
>         };
> 
>         foo {
>                 ...
>                 resets = <&reset 0>; /* uses first reset line of the gpio-reset controller */
>         };

That is what I initially proposed...

> I realize it would be a little more verbose, but it also seems more
> regular and wouldn't stand out from the rest of the reset interfaces.

... but it can also be argued that GPIO resets shouldn't stand out from
other GPIOs.

Mark Rutland spoke out against having a 'GPIO reset device' node in the
device tree:

http://comments.gmane.org/gmane.linux.drivers.devicetree/41596

and I see his point. Using different bindings for reset controller IPs
and for single GPIOs better describes the actual hardware and it is less
Linux specific: it still allows an OS without gpio-reset framework to
let each driver handle the GPIO itself.

Also Stephen Warren pointed out that we'll have to support the existing
GPIO bindings anyway: in the meantime there are a lot of GPIO resets in
various device trees that use the GPIO bindings.

regards
Philipp

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Re: [PATCH v3 1/2] Documentation: Add GPIO reset binding to reset binding documentation

[Philipp Zabel]

Hi Arnd,

Am Freitag, den 10.01.2014, 12:25 +0100 schrieb Philipp Zabel:
> Hi Arnd,
> 
> Am Mittwoch, den 08.01.2014, 17:08 +0100 schrieb Arnd Bergmann:
> > On Wednesday 08 January 2014, Philipp Zabel wrote:
> > > += GPIO Reset consumers =
> > > +
> > > +For the common case of reset lines controlled by GPIOs, the GPIO binding
> > > +documented in devicetree/bindings/gpio/gpio.txt should be used:
> > > +
> > > +Required properties:
> > > +reset-gpios or         Reset GPIO using standard GPIO bindings,
> > > +<name>-reset-gpios:    optionally named to specify the reset line
> > > +
> > > +Optional properties:
> > > +reset-boot-asserted or         Boolean. If set, the corresponding reset is
> > > +<name>-reset-boot-asserted:    initially asserted and should be kept that way
> > > +                               until released by the driver.
> > 
> > I don't get this one. Why would you use a different reset binding for the case
> > where the reset line is connected to the gpio controller rather than a
> > specialized reset controller?
> > 
> > I was expecting to see the definition of a generic reset controller that
> > in turn uses gpio lines, like
> > 
> > 
> >         reset { 
> >                 compatible = "gpio-reset";
> >                 /* provides three reset lines through these GPIOs */
> >                 gpios = <&gpioA 1 &gpioB 7 <gpioD 17>;
> >                 #reset-cells = <1>;
> >         };
> > 
> >         foo {
> >                 ...
> >                 resets = <&reset 0>; /* uses first reset line of the gpio-reset controller */
> >         };
> 
> That is what I initially proposed...
> 
> > I realize it would be a little more verbose, but it also seems more
> > regular and wouldn't stand out from the rest of the reset interfaces.
> 
> ... but it can also be argued that GPIO resets shouldn't stand out from
> other GPIOs.
> 
> Mark Rutland spoke out against having a 'GPIO reset device' node in the
> device tree:
> 
> http://comments.gmane.org/gmane.linux.drivers.devicetree/41596
> 
> and I see his point. Using different bindings for reset controller IPs
> and for single GPIOs better describes the actual hardware and it is less
> Linux specific: it still allows an OS without gpio-reset framework to
> let each driver handle the GPIO itself.
> 
> Also Stephen Warren pointed out that we'll have to support the existing
> GPIO bindings anyway: in the meantime there are a lot of GPIO resets in
> various device trees that use the GPIO bindings.
> 
> regards
> Philipp

do you have further comments on this?

I'd like to request a pull of the changes in
http://git.pengutronix.de/?p=pza/linux.git;a=shortlog;h=refs/heads/reset/for_v3.15
and I wonder whether I should submit that now without the GPIO patches
or hold it back a bit and add them on top.

regards
Philipp

Re: [PATCH v3 1/2] Documentation: Add GPIO reset binding to reset binding documentation

[Philipp Zabel]

Hi Arnd,

Am Freitag, den 10.01.2014, 12:25 +0100 schrieb Philipp Zabel:
> Hi Arnd,
> 
> Am Mittwoch, den 08.01.2014, 17:08 +0100 schrieb Arnd Bergmann:
> > On Wednesday 08 January 2014, Philipp Zabel wrote:
> > > += GPIO Reset consumers =
> > > +
> > > +For the common case of reset lines controlled by GPIOs, the GPIO binding
> > > +documented in devicetree/bindings/gpio/gpio.txt should be used:
> > > +
> > > +Required properties:
> > > +reset-gpios or         Reset GPIO using standard GPIO bindings,
> > > +<name>-reset-gpios:    optionally named to specify the reset line
> > > +
> > > +Optional properties:
> > > +reset-boot-asserted or         Boolean. If set, the corresponding reset is
> > > +<name>-reset-boot-asserted:    initially asserted and should be kept that way
> > > +                               until released by the driver.
> > 
> > I don't get this one. Why would you use a different reset binding for the case
> > where the reset line is connected to the gpio controller rather than a
> > specialized reset controller?
> > 
> > I was expecting to see the definition of a generic reset controller that
> > in turn uses gpio lines, like
> > 
> > 
> >         reset { 
> >                 compatible = "gpio-reset";
> >                 /* provides three reset lines through these GPIOs */
> >                 gpios = <&gpioA 1 &gpioB 7 <gpioD 17>;
> >                 #reset-cells = <1>;
> >         };
> > 
> >         foo {
> >                 ...
> >                 resets = <&reset 0>; /* uses first reset line of the gpio-reset controller */
> >         };
> 
> That is what I initially proposed...
> 
> > I realize it would be a little more verbose, but it also seems more
> > regular and wouldn't stand out from the rest of the reset interfaces.
> 
> ... but it can also be argued that GPIO resets shouldn't stand out from
> other GPIOs.
> 
> Mark Rutland spoke out against having a 'GPIO reset device' node in the
> device tree:
> 
> http://comments.gmane.org/gmane.linux.drivers.devicetree/41596
> 
> and I see his point. Using different bindings for reset controller IPs
> and for single GPIOs better describes the actual hardware and it is less
> Linux specific: it still allows an OS without gpio-reset framework to
> let each driver handle the GPIO itself.
> 
> Also Stephen Warren pointed out that we'll have to support the existing
> GPIO bindings anyway: in the meantime there are a lot of GPIO resets in
> various device trees that use the GPIO bindings.
> 
> regards
> Philipp

do you have further comments on this?

I'd like to request a pull of the changes in
http://git.pengutronix.de/?p=pza/linux.git;a=shortlog;h=refs/heads/reset/for_v3.15
and I wonder whether I should submit that now without the GPIO patches
or hold it back a bit and add them on top.

regards
Philipp

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Re: [PATCH v3 1/2] Documentation: Add GPIO reset binding to reset binding documentation

[Philipp Zabel]

Am Donnerstag, den 06.02.2014, 16:44 +0100 schrieb Philipp Zabel:
> Hi Arnd,
> 
> Am Freitag, den 10.01.2014, 12:25 +0100 schrieb Philipp Zabel:
> > Hi Arnd,
> > 
> > Am Mittwoch, den 08.01.2014, 17:08 +0100 schrieb Arnd Bergmann:
> > > On Wednesday 08 January 2014, Philipp Zabel wrote:
> > > > += GPIO Reset consumers =
> > > > +
> > > > +For the common case of reset lines controlled by GPIOs, the GPIO binding
> > > > +documented in devicetree/bindings/gpio/gpio.txt should be used:
> > > > +
> > > > +Required properties:
> > > > +reset-gpios or         Reset GPIO using standard GPIO bindings,
> > > > +<name>-reset-gpios:    optionally named to specify the reset line
> > > > +
> > > > +Optional properties:
> > > > +reset-boot-asserted or         Boolean. If set, the corresponding reset is
> > > > +<name>-reset-boot-asserted:    initially asserted and should be kept that way
> > > > +                               until released by the driver.
> > > 
> > > I don't get this one. Why would you use a different reset binding for the case
> > > where the reset line is connected to the gpio controller rather than a
> > > specialized reset controller?
> > > 
> > > I was expecting to see the definition of a generic reset controller that
> > > in turn uses gpio lines, like
> > > 
> > > 
> > >         reset { 
> > >                 compatible = "gpio-reset";
> > >                 /* provides three reset lines through these GPIOs */
> > >                 gpios = <&gpioA 1 &gpioB 7 <gpioD 17>;
> > >                 #reset-cells = <1>;
> > >         };
> > > 
> > >         foo {
> > >                 ...
> > >                 resets = <&reset 0>; /* uses first reset line of the gpio-reset controller */
> > >         };
> > 
> > That is what I initially proposed...
> > 
> > > I realize it would be a little more verbose, but it also seems more
> > > regular and wouldn't stand out from the rest of the reset interfaces.
> > 
> > ... but it can also be argued that GPIO resets shouldn't stand out from
> > other GPIOs.
> > 
> > Mark Rutland spoke out against having a 'GPIO reset device' node in the
> > device tree:
> > 
> > http://comments.gmane.org/gmane.linux.drivers.devicetree/41596
> > 
> > and I see his point. Using different bindings for reset controller IPs
> > and for single GPIOs better describes the actual hardware and it is less
> > Linux specific: it still allows an OS without gpio-reset framework to
> > let each driver handle the GPIO itself.
> > 
> > Also Stephen Warren pointed out that we'll have to support the existing
> > GPIO bindings anyway: in the meantime there are a lot of GPIO resets in
> > various device trees that use the GPIO bindings.
> > 
> > regards
> > Philipp
> 
> do you have further comments on this?

Yes? No? Maybe later?

> I'd like to request a pull of the changes in
> http://git.pengutronix.de/?p=pza/linux.git;a=shortlog;h=refs/heads/reset/for_v3.15
> and I wonder whether I should submit that now without the GPIO patches
> or hold it back a bit and add them on top.

regards
Philipp

Re: [PATCH v3 1/2] Documentation: Add GPIO reset binding to reset binding documentation

[Philipp Zabel]

Am Donnerstag, den 06.02.2014, 16:44 +0100 schrieb Philipp Zabel:
> Hi Arnd,
> 
> Am Freitag, den 10.01.2014, 12:25 +0100 schrieb Philipp Zabel:
> > Hi Arnd,
> > 
> > Am Mittwoch, den 08.01.2014, 17:08 +0100 schrieb Arnd Bergmann:
> > > On Wednesday 08 January 2014, Philipp Zabel wrote:
> > > > += GPIO Reset consumers =
> > > > +
> > > > +For the common case of reset lines controlled by GPIOs, the GPIO binding
> > > > +documented in devicetree/bindings/gpio/gpio.txt should be used:
> > > > +
> > > > +Required properties:
> > > > +reset-gpios or         Reset GPIO using standard GPIO bindings,
> > > > +<name>-reset-gpios:    optionally named to specify the reset line
> > > > +
> > > > +Optional properties:
> > > > +reset-boot-asserted or         Boolean. If set, the corresponding reset is
> > > > +<name>-reset-boot-asserted:    initially asserted and should be kept that way
> > > > +                               until released by the driver.
> > > 
> > > I don't get this one. Why would you use a different reset binding for the case
> > > where the reset line is connected to the gpio controller rather than a
> > > specialized reset controller?
> > > 
> > > I was expecting to see the definition of a generic reset controller that
> > > in turn uses gpio lines, like
> > > 
> > > 
> > >         reset { 
> > >                 compatible = "gpio-reset";
> > >                 /* provides three reset lines through these GPIOs */
> > >                 gpios = <&gpioA 1 &gpioB 7 <gpioD 17>;
> > >                 #reset-cells = <1>;
> > >         };
> > > 
> > >         foo {
> > >                 ...
> > >                 resets = <&reset 0>; /* uses first reset line of the gpio-reset controller */
> > >         };
> > 
> > That is what I initially proposed...
> > 
> > > I realize it would be a little more verbose, but it also seems more
> > > regular and wouldn't stand out from the rest of the reset interfaces.
> > 
> > ... but it can also be argued that GPIO resets shouldn't stand out from
> > other GPIOs.
> > 
> > Mark Rutland spoke out against having a 'GPIO reset device' node in the
> > device tree:
> > 
> > http://comments.gmane.org/gmane.linux.drivers.devicetree/41596
> > 
> > and I see his point. Using different bindings for reset controller IPs
> > and for single GPIOs better describes the actual hardware and it is less
> > Linux specific: it still allows an OS without gpio-reset framework to
> > let each driver handle the GPIO itself.
> > 
> > Also Stephen Warren pointed out that we'll have to support the existing
> > GPIO bindings anyway: in the meantime there are a lot of GPIO resets in
> > various device trees that use the GPIO bindings.
> > 
> > regards
> > Philipp
> 
> do you have further comments on this?

Yes? No? Maybe later?

> I'd like to request a pull of the changes in
> http://git.pengutronix.de/?p=pza/linux.git;a=shortlog;h=refs/heads/reset/for_v3.15
> and I wonder whether I should submit that now without the GPIO patches
> or hold it back a bit and add them on top.

regards
Philipp

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