[PATCH v6 0/8] Reset controller API to reset IP modules on i.MX5 and i.MX6

[PATCH v6 0/8] Reset controller API to reset IP modules on i.MX5 and i.MX6

[Philipp Zabel]

[Added Arnd and Greg to the recipients] I think the first three patches
of this series are candidates to go through Arnd's tree. Arnd, would you
take those patches?
        [PATCH v6 1/8] dt: describe base reset signal binding
        [PATCH v6 2/8] reset: Add reset controller API
        [PATCH v6 3/8] reset: Add driver for gpio-controlled reset pins

The system reset controller (SRC) on i.MX51, i.MX53, and i.MX6q controls
reset lines to the GPU, VPU, IPU, and OpenVG IP modules.

The following patches add a simple API for devices to request being reset
by separate reset controller hardware and implements the reset signal
device tree binding proposed by Stephen Warren. Contrary to Tegra hardware,
the i.MX SRC contains self-deasserting reset registers, so I've included
both ops to manually assert/deassert a reset line, as well as a "reset"
operation that is supposed to assert the reset line and wait for it to
deassert.

The i.MX SRC is enhanced to provide a reset controller and the IPU driver
is made to request being reset by calling the device_reset(&pdev->dev)
convenience wrapper during probing.

No changes since v5, I just reordered the series.

regards
Philipp

---
 .../devicetree/bindings/reset/fsl,imx-src.txt      |  49 ++++
 .../devicetree/bindings/reset/gpio-reset.txt       |  37 +++
 Documentation/devicetree/bindings/reset/reset.txt  |  75 ++++++
 .../bindings/staging/imx-drm/fsl-imx-drm.txt       |   3 +
 arch/arm/boot/dts/imx51.dtsi                       |   7 +
 arch/arm/boot/dts/imx53.dtsi                       |   7 +
 arch/arm/boot/dts/imx6q.dtsi                       |   1 +
 arch/arm/boot/dts/imx6qdl.dtsi                     |   4 +-
 arch/arm/mach-imx/Kconfig                          |   3 +
 arch/arm/mach-imx/mm-imx5.c                        |   2 +
 arch/arm/mach-imx/src.c                            |  69 ++++-
 drivers/Kconfig                                    |   2 +
 drivers/Makefile                                   |   3 +
 drivers/reset/Kconfig                              |  26 ++
 drivers/reset/Makefile                             |   2 +
 drivers/reset/core.c                               | 297 +++++++++++++++++++++
 drivers/reset/gpio-reset.c                         | 208 +++++++++++++++
 drivers/staging/imx-drm/ipu-v3/ipu-common.c        |  12 +-
 include/linux/reset-controller.h                   |  51 ++++
 include/linux/reset.h                              |  17 ++
 20 files changed, 870 insertions(+), 5 deletions(-)

[PATCH v6 1/8] dt: describe base reset signal binding

[Philipp Zabel]

From: Stephen Warren <swarren@nvidia.com>

This binding is intended to represent the hardware reset signals present
internally in most IC (SoC, FPGA, ...) designs.
It consists of a binding for a reset controller device (provider), and a
pair of properties, "resets" and "reset-names", to link a device node
(consumer) to its reset controller via phandle, similarly to the clock
and interrupt bindings.

The reset controller has all information necessary to reset the consumer
device. That could be provided via device tree, or it could be implemented
in hardware.
The aim is to enable device drivers to request a framework API to issue a
reset simply by providing their struct device pointer as the most common
case.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Marek Vasut <marex@denx.de>
---
 Documentation/devicetree/bindings/reset/reset.txt | 75 +++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reset/reset.txt

diff --git a/Documentation/devicetree/bindings/reset/reset.txt b/Documentation/devicetree/bindings/reset/reset.txt
new file mode 100644
index 0000000..31db6ff
--- /dev/null
+++ b/Documentation/devicetree/bindings/reset/reset.txt
@@ -0,0 +1,75 @@
+= Reset Signal Device Tree Bindings =
+
+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.
+
+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
+reset consumer (the module being reset, or a module managing when a sub-
+ordinate module is reset). This binding exists to represent the provider and
+consumer, and provide a way to couple the two together.
+
+A reset signal is represented by the phandle of the provider, plus a reset
+specifier - a list of DT cells that represents the reset signal within the
+provider. The length (number of cells) and semantics of the reset specifier
+are dictated by the binding of the reset provider, although common schemes
+are described below.
+
+A word on where to place reset signal consumers in device tree: It is possible
+in hardware for a reset signal to affect multiple logically separate HW blocks
+at once. In this case, it would be unwise to represent this reset signal in
+the DT node of each affected HW block, since if activated, an unrelated block
+may be reset. Instead, reset signals should be represented in the DT node
+where it makes most sense to control it; this may be a bus node if all
+children of the bus are affected by the reset signal, or an individual HW
+block node for dedicated reset signals. The intent of this binding is to give
+appropriate software access to the reset signals in order to manage the HW,
+rather than to slavishly enumerate the reset signal that affects each HW
+block.
+
+= Reset providers =
+
+Required properties:
+#reset-cells:	Number of cells in a reset specifier; Typically 0 for nodes
+		with a single reset output and 1 for nodes with multiple
+		reset outputs.
+
+For example:
+
+	rst: reset-controller {
+		#reset-cells = <1>;
+	};
+
+= Reset consumers =
+
+Required properties:
+resets:		List of phandle and reset specifier pairs, one pair
+		for each reset signal that affects the device, or that the
+		device manages. Note: if the reset provider specifies '0' for
+		#reset-cells, then only the phandle portion of the pair will
+		appear.
+
+Optional properties:
+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.
+
+For example:
+
+	device {
+		resets = <&rst 20>;
+		reset-names = "reset";
+	};
+
+This represents a device with a single reset signal named "reset".
+
+	bus {
+		resets = <&rst 10> <&rst 11> <&rst 12> <&rst 11>;
+		reset-names = "i2s1", "i2s2", "dma", "mixer";
+	};
+
+This represents a bus that controls the reset signal of each of four sub-
+ordinate devices. Consider for example a bus that fails to operate unless no
+child device has reset asserted.
-- 
1.8.2.rc2

[PATCH v6 2/8] reset: Add reset controller API

[Philipp Zabel]

This adds a simple API for devices to request being reset
by separate reset controller hardware and implements the
reset signal device tree binding.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Marek Vasut <marex@denx.de>
---
 drivers/Kconfig                  |   2 +
 drivers/Makefile                 |   3 +
 drivers/reset/Kconfig            |  13 ++
 drivers/reset/Makefile           |   1 +
 drivers/reset/core.c             | 297 +++++++++++++++++++++++++++++++++++++++
 include/linux/reset-controller.h |  51 +++++++
 include/linux/reset.h            |  17 +++
 7 files changed, 384 insertions(+)
 create mode 100644 drivers/reset/Kconfig
 create mode 100644 drivers/reset/Makefile
 create mode 100644 drivers/reset/core.c
 create mode 100644 include/linux/reset-controller.h
 create mode 100644 include/linux/reset.h

diff --git a/drivers/Kconfig b/drivers/Kconfig
index 202fa6d..847f8e3 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -162,4 +162,6 @@ source "drivers/irqchip/Kconfig"
 
 source "drivers/ipack/Kconfig"
 
+source "drivers/reset/Kconfig"
+
 endmenu
diff --git a/drivers/Makefile b/drivers/Makefile
index dce39a9..1a64c4c 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -37,6 +37,9 @@ obj-$(CONFIG_XEN)		+= xen/
 # regulators early, since some subsystems rely on them to initialize
 obj-$(CONFIG_REGULATOR)		+= regulator/
 
+# reset controllers early, since gpu drivers might rely on them to initialize
+obj-$(CONFIG_RESET_CONTROLLER)	+= reset/
+
 # tty/ comes before char/ so that the VT console is the boot-time
 # default.
 obj-y				+= tty/
diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
new file mode 100644
index 0000000..c9d04f7
--- /dev/null
+++ b/drivers/reset/Kconfig
@@ -0,0 +1,13 @@
+config ARCH_HAS_RESET_CONTROLLER
+	bool
+
+menuconfig RESET_CONTROLLER
+	bool "Reset Controller Support"
+	default y if ARCH_HAS_RESET_CONTROLLER
+	help
+	  Generic Reset Controller support.
+
+	  This framework is designed to abstract reset handling of devices
+	  via GPIOs or SoC-internal reset controller modules.
+
+	  If unsure, say no.
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
new file mode 100644
index 0000000..1e2d83f
--- /dev/null
+++ b/drivers/reset/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_RESET_CONTROLLER) += core.o
diff --git a/drivers/reset/core.c b/drivers/reset/core.c
new file mode 100644
index 0000000..a258277
--- /dev/null
+++ b/drivers/reset/core.c
@@ -0,0 +1,297 @@
+/*
+ * 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.
+ */
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/reset.h>
+#include <linux/reset-controller.h>
+#include <linux/slab.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
+ * @flags: a flags pointer to fill in (optional)
+ *
+ * This simple translation function should be used for reset controllers
+ * with 1:1 mapping, where reset lines can be indexed by number without gaps.
+ */
+int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
+			  const struct of_phandle_args *reset_spec)
+{
+	if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells))
+		return -EINVAL;
+
+	if (reset_spec->args[0] >= rcdev->nr_resets)
+		return -EINVAL;
+
+	return reset_spec->args[0];
+}
+EXPORT_SYMBOL_GPL(of_reset_simple_xlate);
+
+/**
+ * reset_controller_register - register a reset controller device
+ * @rcdev: a pointer to the initialized reset controller device
+ */
+int reset_controller_register(struct reset_controller_dev *rcdev)
+{
+	if (!rcdev->of_xlate) {
+		rcdev->of_reset_n_cells = 1;
+		rcdev->of_xlate = of_reset_simple_xlate;
+	}
+
+	mutex_lock(&reset_controller_list_mutex);
+	list_add(&rcdev->list, &reset_controller_list);
+	mutex_unlock(&reset_controller_list_mutex);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(reset_controller_register);
+
+/**
+ * reset_controller_unregister - unregister a reset controller device
+ * @rcdev: a pointer to the reset controller device
+ */
+void reset_controller_unregister(struct reset_controller_dev *rcdev)
+{
+	mutex_lock(&reset_controller_list_mutex);
+	list_del(&rcdev->list);
+	mutex_unlock(&reset_controller_list_mutex);
+}
+EXPORT_SYMBOL_GPL(reset_controller_unregister);
+
+/**
+ * reset_control_reset - reset the controlled device
+ * @rstc: reset controller
+ */
+int reset_control_reset(struct reset_control *rstc)
+{
+	if (rstc->rcdev->ops->reset)
+		return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id);
+
+	return -ENOSYS;
+}
+EXPORT_SYMBOL_GPL(reset_control_reset);
+
+/**
+ * reset_control_assert - asserts the reset line
+ * @rstc: reset controller
+ */
+int reset_control_assert(struct reset_control *rstc)
+{
+	if (rstc->rcdev->ops->assert)
+		return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id);
+
+	return -ENOSYS;
+}
+EXPORT_SYMBOL_GPL(reset_control_assert);
+
+/**
+ * reset_control_deassert - deasserts the reset line
+ * @rstc: reset controller
+ */
+int reset_control_deassert(struct reset_control *rstc)
+{
+	if (rstc->rcdev->ops->deassert)
+		return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id);
+
+	return -ENOSYS;
+}
+EXPORT_SYMBOL_GPL(reset_control_deassert);
+
+/**
+ * reset_control_get - Lookup and obtain a reference to a reset controller.
+ * @dev: device to be reset by the controller
+ * @id: reset line name
+ *
+ * Returns a struct reset_control or IS_ERR() condition containing errno.
+ *
+ * Use of id names is optional.
+ */
+struct reset_control *reset_control_get(struct device *dev, const char *id)
+{
+	struct reset_control *rstc = ERR_PTR(-EPROBE_DEFER);
+	struct reset_controller_dev *r, *rcdev;
+	struct of_phandle_args args;
+	int index = 0;
+	int rstc_id;
+	int ret;
+
+	if (!dev)
+		return ERR_PTR(-EINVAL);
+
+	if (id)
+		index = of_property_match_string(dev->of_node,
+						 "reset-names", id);
+	ret = of_parse_phandle_with_args(dev->of_node, "resets", "#reset-cells",
+					 index, &args);
+	if (ret)
+		return ERR_PTR(ret);
+
+	mutex_lock(&reset_controller_list_mutex);
+	rcdev = NULL;
+	list_for_each_entry(r, &reset_controller_list, list) {
+		if (args.np == r->of_node) {
+			rcdev = r;
+			break;
+		}
+	}
+	of_node_put(args.np);
+
+	if (!rcdev) {
+		mutex_unlock(&reset_controller_list_mutex);
+		return ERR_PTR(-ENODEV);
+	}
+
+	rstc_id = rcdev->of_xlate(rcdev, &args);
+	if (rstc_id < 0) {
+		mutex_unlock(&reset_controller_list_mutex);
+		return ERR_PTR(rstc_id);
+	}
+
+	try_module_get(rcdev->owner);
+	mutex_unlock(&reset_controller_list_mutex);
+
+	rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
+	if (!rstc) {
+		module_put(rstc->rcdev->owner);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	rstc->dev = dev;
+	rstc->rcdev = rcdev;
+	rstc->id = rstc_id;
+
+	return rstc;
+}
+EXPORT_SYMBOL_GPL(reset_control_get);
+
+/**
+ * reset_control_put - free the reset controller
+ * @rstc: reset controller
+ */
+
+void reset_control_put(struct reset_control *rstc)
+{
+	if (IS_ERR(rstc))
+		return;
+
+	module_put(rstc->rcdev->owner);
+	kfree(rstc);
+}
+EXPORT_SYMBOL_GPL(reset_control_put);
+
+static void devm_reset_control_release(struct device *dev, void *res)
+{
+	reset_control_put(*(struct reset_control **)res);
+}
+
+/**
+ * devm_reset_control_get - resource managed reset_control_get()
+ * @dev: device to be reset by the controller
+ * @id: reset line name
+ *
+ * Managed reset_control_get(). For reset controllers returned from this
+ * function, reset_control_put() is called automatically on driver detach.
+ * See reset_control_get() for more information.
+ */
+struct reset_control *devm_reset_control_get(struct device *dev, const char *id)
+{
+	struct reset_control **ptr, *rstc;
+
+	ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr),
+			   GFP_KERNEL);
+	if (!ptr)
+		return ERR_PTR(-ENOMEM);
+
+	rstc = reset_control_get(dev, id);
+	if (!IS_ERR(rstc)) {
+		*ptr = rstc;
+		devres_add(dev, ptr);
+	} else {
+		devres_free(ptr);
+	}
+
+	return rstc;
+}
+EXPORT_SYMBOL_GPL(devm_reset_control_get);
+
+static int devm_reset_control_match(struct device *dev, void *res, void *data)
+{
+	struct reset_control **rstc = res;
+	if (WARN_ON(!rstc || !*rstc))
+		return 0;
+	return *rstc == data;
+}
+
+/**
+ * devm_reset_control_put - resource managed reset_control_put()
+ * @rstc: reset controller to free
+ *
+ * Deallocate a reset control allocated withd devm_reset_control_get().
+ * This function will not need to be called normally, as devres will take
+ * care of freeing the resource.
+ */
+void devm_reset_control_put(struct reset_control *rstc)
+{
+	int ret;
+
+	ret = devres_release(rstc->dev, devm_reset_control_release,
+			     devm_reset_control_match, rstc);
+	if (ret)
+		WARN_ON(ret);
+}
+EXPORT_SYMBOL_GPL(devm_reset_control_put);
+
+/**
+ * device_reset - find reset controller associated with the device
+ *                and perform reset
+ * @dev: device to be reset by the controller
+ *
+ * Convenience wrapper for reset_control_get() and reset_control_reset().
+ * This is useful for the common case of devices with single, dedicated reset
+ * lines.
+ */
+int device_reset(struct device *dev)
+{
+	struct reset_control *rstc;
+	int ret;
+
+	rstc = reset_control_get(dev, NULL);
+	if (IS_ERR(rstc))
+		return PTR_ERR(rstc);
+
+	ret = reset_control_reset(rstc);
+
+	reset_control_put(rstc);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(device_reset);
diff --git a/include/linux/reset-controller.h b/include/linux/reset-controller.h
new file mode 100644
index 0000000..2f61311
--- /dev/null
+++ b/include/linux/reset-controller.h
@@ -0,0 +1,51 @@
+#ifndef _LINUX_RESET_CONTROLLER_H_
+#define _LINUX_RESET_CONTROLLER_H_
+
+#include <linux/list.h>
+
+struct reset_controller_dev;
+
+/**
+ * struct reset_control_ops
+ *
+ * @reset: for self-deasserting resets, does all necessary
+ *         things to reset the device
+ * @assert: manually assert the reset line, if supported
+ * @deassert: manually deassert the reset line, if supported
+ */
+struct reset_control_ops {
+	int (*reset)(struct reset_controller_dev *rcdev, unsigned long id);
+	int (*assert)(struct reset_controller_dev *rcdev, unsigned long id);
+	int (*deassert)(struct reset_controller_dev *rcdev, unsigned long id);
+};
+
+struct module;
+struct device_node;
+
+/**
+ * struct reset_controller_dev - reset controller entity that might
+ *                               provide multiple reset controls
+ * @ops: a pointer to device specific struct reset_control_ops
+ * @owner: kernel module of the reset controller driver
+ * @list: internal list of reset controller devices
+ * @of_node: corresponding device tree node as phandle target
+ * @of_reset_n_cells: number of cells in reset line specifiers
+ * @of_xlate: translation function to translate from specifier as found in the
+ *            device tree to id as given to the reset control ops
+ * @nr_resets: number of reset controls in this reset controller device
+ */
+struct reset_controller_dev {
+	struct reset_control_ops *ops;
+	struct module *owner;
+	struct list_head list;
+	struct device_node *of_node;
+	int of_reset_n_cells;
+	int (*of_xlate)(struct reset_controller_dev *rcdev,
+			const struct of_phandle_args *reset_spec);
+	unsigned int nr_resets;
+};
+
+int reset_controller_register(struct reset_controller_dev *rcdev);
+void reset_controller_unregister(struct reset_controller_dev *rcdev);
+
+#endif
diff --git a/include/linux/reset.h b/include/linux/reset.h
new file mode 100644
index 0000000..6082247
--- /dev/null
+++ b/include/linux/reset.h
@@ -0,0 +1,17 @@
+#ifndef _LINUX_RESET_H_
+#define _LINUX_RESET_H_
+
+struct device;
+struct reset_control;
+
+int reset_control_reset(struct reset_control *rstc);
+int reset_control_assert(struct reset_control *rstc);
+int reset_control_deassert(struct reset_control *rstc);
+
+struct reset_control *reset_control_get(struct device *dev, const char *id);
+void reset_control_put(struct reset_control *rstc);
+struct reset_control *devm_reset_control_get(struct device *dev, const char *id);
+
+int device_reset(struct device *dev);
+
+#endif
-- 
1.8.2.rc2

[PATCH v6 3/8] reset: Add driver for gpio-controlled reset pins

[Philipp Zabel]

This driver implements a reset controller device that toggles gpios
connected to reset pins of peripheral ICs. The delay between assertion
and de-assertion of the reset signal can be configured.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
---
 .../devicetree/bindings/reset/gpio-reset.txt       |  37 ++++
 drivers/reset/Kconfig                              |  13 ++
 drivers/reset/Makefile                             |   1 +
 drivers/reset/gpio-reset.c                         | 208 +++++++++++++++++++++
 4 files changed, 259 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reset/gpio-reset.txt
 create mode 100644 drivers/reset/gpio-reset.c

diff --git a/Documentation/devicetree/bindings/reset/gpio-reset.txt b/Documentation/devicetree/bindings/reset/gpio-reset.txt
new file mode 100644
index 0000000..1f203eb
--- /dev/null
+++ b/Documentation/devicetree/bindings/reset/gpio-reset.txt
@@ -0,0 +1,37 @@
+GPIO reset controller
+=====================
+
+A GPIO reset controller controls a number of GPIOs that are connected
+to reset pins of peripheral ICs.
+
+Please also refer to reset.txt in this directory for common reset
+controller binding usage.
+
+Required properties:
+- compatible: Should be "gpio-reset"
+- reset-gpios: List of gpios used as reset lines. The gpio specifier for this
+               property depends on the gpio controller that provides the gpio.
+- #reset-cells: 1, see below
+
+Optional properties:
+- reset-delays: List of delays in microseconds. The corresponding gpio reset
+                line should be asserted for this duration to reset.
+- initially-in-reset: List of integers. Zero if the initial state should be
+                      a deasserted reset line, nonzero if the line should be
+                      kept in reset.
+
+example:
+
+gpio_reset: gpio-reset {
+	compatible = "gpio-reset";
+	reset-gpios = <&gpio5 0 1>; /* active-low */
+	reset-delays = <10000>; /* 10 ms */
+	initially-in-reset: <1>;
+	#reset-cells = <1>;
+};
+
+/* Device with nRESET pin connected to GPIO5_0 */
+sii902x at 39 {
+	/* ... */
+	resets = <&gpio_reset 0>; /* active-low GPIO5_0, 10 ms reset delay */
+};
diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index c9d04f7..e728d36 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -11,3 +11,16 @@ menuconfig RESET_CONTROLLER
 	  via GPIOs or SoC-internal reset controller modules.
 
 	  If unsure, say no.
+
+if RESET_CONTROLLER
+
+config RESET_GPIO
+	tristate "GPIO reset controller support"
+	depends on GENERIC_GPIO
+	help
+	  This driver provides support for reset lines that are controlled
+	  directly by GPIOs.
+	  The delay between assertion and de-assertion of the reset signal
+	  can be configured.
+
+endif
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 1e2d83f..b854f20 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_RESET_CONTROLLER) += core.o
+obj-$(CONFIG_RESET_GPIO) += gpio-reset.o
diff --git a/drivers/reset/gpio-reset.c b/drivers/reset/gpio-reset.c
new file mode 100644
index 0000000..3e3c363
--- /dev/null
+++ b/drivers/reset/gpio-reset.c
@@ -0,0 +1,208 @@
+/*
+ * GPIO Reset Controller driver
+ *
+ * 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/delay.h>
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/module.h>
+#include <linux/of_gpio.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+
+struct gpio_reset {
+	unsigned int gpio;
+	bool active_low;
+};
+
+struct gpio_reset_data {
+	struct reset_controller_dev rcdev;
+	/* these arrays contain a number of elements equal to rcdev.nr_resets */
+	struct gpio_reset *gpios;
+	u32 *delays_us;
+};
+
+static void __gpio_reset_set(struct reset_controller_dev *rcdev,
+		unsigned long gpio_idx, int asserted)
+{
+	struct gpio_reset_data *drvdata = container_of(rcdev,
+			struct gpio_reset_data, rcdev);
+	int value = asserted;
+
+	if (drvdata->gpios[gpio_idx].active_low)
+		value = !value;
+
+	gpio_set_value(drvdata->gpios[gpio_idx].gpio, value);
+}
+
+static int gpio_reset(struct reset_controller_dev *rcdev,
+		unsigned long gpio_idx)
+{
+	struct gpio_reset_data *drvdata = container_of(rcdev,
+			struct gpio_reset_data, rcdev);
+
+	if (gpio_idx >= rcdev->nr_resets)
+		return -EINVAL;
+
+	if (drvdata->delays_us == NULL)
+		return -ENOSYS;
+
+	__gpio_reset_set(rcdev, gpio_idx, 1);
+	udelay(drvdata->delays_us[gpio_idx]);
+	__gpio_reset_set(rcdev, gpio_idx, 0);
+
+	return 0;
+}
+
+static int gpio_reset_assert(struct reset_controller_dev *rcdev,
+		unsigned long gpio_idx)
+{
+	if (gpio_idx >= rcdev->nr_resets)
+		return -EINVAL;
+
+	__gpio_reset_set(rcdev, gpio_idx, 1);
+
+	return 0;
+}
+
+static int gpio_reset_deassert(struct reset_controller_dev *rcdev,
+		unsigned long gpio_idx)
+{
+	if (gpio_idx >= rcdev->nr_resets)
+		return -EINVAL;
+
+	__gpio_reset_set(rcdev, gpio_idx, 0);
+
+	return 0;
+}
+
+static struct reset_control_ops gpio_reset_ops = {
+	.reset = gpio_reset,
+	.assert = gpio_reset_assert,
+	.deassert = gpio_reset_deassert,
+};
+
+static int gpio_reset_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct gpio_reset_data *drvdata;
+	enum of_gpio_flags flags;
+	u32 *initially_in_reset;
+	int nr_gpios;
+	int ret;
+	int i;
+
+	drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
+	if (drvdata == NULL)
+		return -ENOMEM;
+
+	nr_gpios = of_gpio_named_count(np, "reset-gpios");
+	if (nr_gpios < 1)
+		return -EINVAL;
+
+	drvdata->gpios = devm_kzalloc(&pdev->dev, sizeof(struct gpio_reset) *
+			nr_gpios, GFP_KERNEL);
+	if (drvdata->gpios == NULL)
+		return -ENOMEM;
+
+	for (i = 0; i < nr_gpios; i++) {
+		drvdata->gpios[i].gpio = of_get_named_gpio_flags(np,
+				"reset-gpios", i, &flags);
+		if (drvdata->gpios[i].gpio == -EPROBE_DEFER)
+			return drvdata->gpios[i].gpio;
+		else if (drvdata->gpios[i].gpio < 0) {
+			dev_err(&pdev->dev, "invalid gpio for reset %d\n", i);
+			return drvdata->gpios[i].gpio;
+		}
+
+		drvdata->gpios[i].active_low = flags & OF_GPIO_ACTIVE_LOW;
+	}
+
+	if (of_find_property(np, "reset-delays", NULL)) {
+		drvdata->delays_us = devm_kzalloc(&pdev->dev, sizeof(u32) *
+				nr_gpios, GFP_KERNEL);
+		if (drvdata->delays_us == NULL)
+			return -ENOMEM;
+
+		ret = of_property_read_u32_array(np, "reset-delays",
+				drvdata->delays_us, nr_gpios);
+		if (ret < 0)
+			return ret;
+	}
+
+	initially_in_reset = devm_kzalloc(&pdev->dev, sizeof(u32) *
+			nr_gpios, GFP_KERNEL);
+	if (initially_in_reset == NULL)
+		return -ENOMEM;
+	if (of_find_property(np, "initially-in-reset", NULL)) {
+		ret = of_property_read_u32_array(np, "initially-in-reset",
+				initially_in_reset, nr_gpios);
+		if (ret < 0)
+			return ret;
+	}
+
+	for (i = 0; i < nr_gpios; i++) {
+		unsigned long gpio_flags = GPIOF_OUT_INIT_LOW;
+
+		if (drvdata->gpios[i].active_low ^ (!!initially_in_reset[i]))
+			gpio_flags = GPIOF_OUT_INIT_HIGH;
+
+		ret = devm_gpio_request_one(&pdev->dev, drvdata->gpios[i].gpio,
+				gpio_flags, NULL);
+		if (ret < 0) {
+			dev_err(&pdev->dev, "failed to request gpio %d for reset %d\n",
+					drvdata->gpios[i].gpio, i);
+			return ret;
+		}
+	}
+
+	devm_kfree(&pdev->dev, initially_in_reset);
+
+	drvdata->rcdev.of_node = np;
+	drvdata->rcdev.owner = THIS_MODULE;
+	drvdata->rcdev.nr_resets = nr_gpios;
+	drvdata->rcdev.ops = &gpio_reset_ops;
+	reset_controller_register(&drvdata->rcdev);
+
+	platform_set_drvdata(pdev, drvdata);
+
+	return 0;
+}
+
+static int gpio_reset_remove(struct platform_device *pdev)
+{
+	struct gpio_reset_data *drvdata = platform_get_drvdata(pdev);
+
+	reset_controller_unregister(&drvdata->rcdev);
+
+	return 0;
+}
+
+static struct of_device_id gpio_reset_dt_ids[] = {
+	{ .compatible = "gpio-reset" },
+	{ }
+};
+
+static struct platform_driver gpio_reset_driver = {
+	.probe = gpio_reset_probe,
+	.remove = gpio_reset_remove,
+	.driver = {
+		.name = "gpio-reset",
+		.owner = THIS_MODULE,
+		.of_match_table = of_match_ptr(gpio_reset_dt_ids),
+	},
+};
+
+module_platform_driver(gpio_reset_driver);
+
+MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
+MODULE_DESCRIPTION("gpio reset controller");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:gpio-reset");
+MODULE_DEVICE_TABLE(of, gpio_reset_dt_ids);
-- 
1.8.2.rc2

[PATCH v6 4/8] ARM i.MX6q: Add GPU, VPU, IPU, and OpenVG resets to System Reset Controller (SRC)

[Philipp Zabel]

The SRC has auto-deasserting reset bits that control reset lines to
the GPU, VPU, IPU, and OpenVG IP modules. This patch adds a reset
controller that can be controlled by those devices using the
reset controller API.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Marek Vasut <marex@denx.de>
---
 .../devicetree/bindings/reset/fsl,imx-src.txt      | 49 ++++++++++++++++
 arch/arm/mach-imx/Kconfig                          |  1 +
 arch/arm/mach-imx/src.c                            | 65 ++++++++++++++++++++++
 3 files changed, 115 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reset/fsl,imx-src.txt

diff --git a/Documentation/devicetree/bindings/reset/fsl,imx-src.txt b/Documentation/devicetree/bindings/reset/fsl,imx-src.txt
new file mode 100644
index 0000000..1330177
--- /dev/null
+++ b/Documentation/devicetree/bindings/reset/fsl,imx-src.txt
@@ -0,0 +1,49 @@
+Freescale i.MX System Reset Controller
+======================================
+
+Please also refer to reset.txt in this directory for common reset
+controller binding usage.
+
+Required properties:
+- compatible: Should be "fsl,<chip>-src"
+- reg: should be register base and length as documented in the
+  datasheet
+- interrupts: Should contain SRC interrupt and CPU WDOG interrupt,
+  in this order.
+- #reset-cells: 1, see below
+
+example:
+
+src: src at 020d8000 {
+        compatible = "fsl,imx6q-src";
+        reg = <0x020d8000 0x4000>;
+        interrupts = <0 91 0x04 0 96 0x04>;
+        #reset-cells = <1>;
+};
+
+Specifying reset lines connected to IP modules
+==============================================
+
+The system reset controller can be used to reset the GPU, VPU,
+IPU, and OpenVG IP modules on i.MX5 and i.MX6 ICs. Those device
+nodes should specify the reset line on the SRC in their resets
+property, containing a phandle to the SRC device node and a
+RESET_INDEX specifying which module to reset, as described in
+reset.txt
+
+example:
+
+        ipu1: ipu at 02400000 {
+                resets = <&src 2>;
+        };
+        ipu2: ipu at 02800000 {
+                resets = <&src 4>;
+        };
+
+The following RESET_INDEX values are valid for i.MX5:
+GPU_RESET     0
+VPU_RESET     1
+IPU1_RESET    2
+OPEN_VG_RESET 3
+The following additional RESET_INDEX value is valid for i.MX6:
+IPU2_RESET    4
diff --git a/arch/arm/mach-imx/Kconfig b/arch/arm/mach-imx/Kconfig
index 4c9c6f9..5052e31 100644
--- a/arch/arm/mach-imx/Kconfig
+++ b/arch/arm/mach-imx/Kconfig
@@ -73,6 +73,7 @@ config HAVE_IMX_MMDC
 
 config HAVE_IMX_SRC
 	def_bool y if SMP
+	select ARCH_HAS_RESET_CONTROLLER
 
 config IMX_HAVE_IOMUX_V1
 	bool
diff --git a/arch/arm/mach-imx/src.c b/arch/arm/mach-imx/src.c
index e15f155..b50eee0 100644
--- a/arch/arm/mach-imx/src.c
+++ b/arch/arm/mach-imx/src.c
@@ -14,16 +14,72 @@
 #include <linux/io.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
+#include <linux/reset-controller.h>
 #include <linux/smp.h>
 #include <asm/smp_plat.h>
 
 #define SRC_SCR				0x000
 #define SRC_GPR1			0x020
 #define BP_SRC_SCR_WARM_RESET_ENABLE	0
+#define BP_SRC_SCR_SW_GPU_RST		1
+#define BP_SRC_SCR_SW_VPU_RST		2
+#define BP_SRC_SCR_SW_IPU1_RST		3
+#define BP_SRC_SCR_SW_OPEN_VG_RST	4
+#define BP_SRC_SCR_SW_IPU2_RST		12
 #define BP_SRC_SCR_CORE1_RST		14
 #define BP_SRC_SCR_CORE1_ENABLE		22
 
 static void __iomem *src_base;
+static DEFINE_SPINLOCK(scr_lock);
+
+static const int sw_reset_bits[5] = {
+	BP_SRC_SCR_SW_GPU_RST,
+	BP_SRC_SCR_SW_VPU_RST,
+	BP_SRC_SCR_SW_IPU1_RST,
+	BP_SRC_SCR_SW_OPEN_VG_RST,
+	BP_SRC_SCR_SW_IPU2_RST
+};
+
+static int imx_src_reset_module(struct reset_controller_dev *rcdev,
+		unsigned long sw_reset_idx)
+{
+	unsigned long timeout;
+	unsigned long flags;
+	int bit;
+	u32 val;
+
+	if (!src_base)
+		return -ENODEV;
+
+	if (sw_reset_idx >= ARRAY_SIZE(sw_reset_bits))
+		return -EINVAL;
+
+	bit = 1 << sw_reset_bits[sw_reset_idx];
+
+	spin_lock_irqsave(&scr_lock, flags);
+	val = readl_relaxed(src_base + SRC_SCR);
+	val |= bit;
+	writel_relaxed(val, src_base + SRC_SCR);
+	spin_unlock_irqrestore(&scr_lock, flags);
+
+	timeout = jiffies + msecs_to_jiffies(1000);
+	while (readl(src_base + SRC_SCR) & bit) {
+		if (time_after(jiffies, timeout))
+			return -ETIME;
+		cpu_relax();
+	}
+
+	return 0;
+}
+
+static struct reset_control_ops imx_src_ops = {
+	.reset = imx_src_reset_module,
+};
+
+static struct reset_controller_dev imx_reset_controller = {
+	.ops = &imx_src_ops,
+	.nr_resets = ARRAY_SIZE(sw_reset_bits),
+};
 
 void imx_enable_cpu(int cpu, bool enable)
 {
@@ -31,9 +87,11 @@ void imx_enable_cpu(int cpu, bool enable)
 
 	cpu = cpu_logical_map(cpu);
 	mask = 1 << (BP_SRC_SCR_CORE1_ENABLE + cpu - 1);
+	spin_lock(&scr_lock);
 	val = readl_relaxed(src_base + SRC_SCR);
 	val = enable ? val | mask : val & ~mask;
 	writel_relaxed(val, src_base + SRC_SCR);
+	spin_unlock(&scr_lock);
 }
 
 void imx_set_cpu_jump(int cpu, void *jump_addr)
@@ -48,9 +106,11 @@ void imx_src_prepare_restart(void)
 	u32 val;
 
 	/* clear enable bits of secondary cores */
+	spin_lock(&scr_lock);
 	val = readl_relaxed(src_base + SRC_SCR);
 	val &= ~(0x7 << BP_SRC_SCR_CORE1_ENABLE);
 	writel_relaxed(val, src_base + SRC_SCR);
+	spin_unlock(&scr_lock);
 
 	/* clear persistent entry register of primary core */
 	writel_relaxed(0, src_base + SRC_GPR1);
@@ -65,11 +125,16 @@ void __init imx_src_init(void)
 	src_base = of_iomap(np, 0);
 	WARN_ON(!src_base);
 
+	imx_reset_controller.of_node = np;
+	reset_controller_register(&imx_reset_controller);
+
 	/*
 	 * force warm reset sources to generate cold reset
 	 * for a more reliable restart
 	 */
+	spin_lock(&scr_lock);
 	val = readl_relaxed(src_base + SRC_SCR);
 	val &= ~(1 << BP_SRC_SCR_WARM_RESET_ENABLE);
 	writel_relaxed(val, src_base + SRC_SCR);
+	spin_unlock(&scr_lock);
 }
-- 
1.8.2.rc2

[PATCH v6 5/8] ARM i.MX6q: Link system reset controller (SRC) to IPU in DT

[Philipp Zabel]

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Marek Vasut <marex@denx.de>
---
 arch/arm/boot/dts/imx6q.dtsi   | 1 +
 arch/arm/boot/dts/imx6qdl.dtsi | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/arch/arm/boot/dts/imx6q.dtsi b/arch/arm/boot/dts/imx6q.dtsi
index cba021e..4cd4f8d 100644
--- a/arch/arm/boot/dts/imx6q.dtsi
+++ b/arch/arm/boot/dts/imx6q.dtsi
@@ -291,6 +291,7 @@
 			interrupts = <0 8 0x4 0 7 0x4>;
 			clocks = <&clks 133>, <&clks 134>, <&clks 137>;
 			clock-names = "bus", "di0", "di1";
+			resets = <&src 4>;
 		};
 	};
 };
diff --git a/arch/arm/boot/dts/imx6qdl.dtsi b/arch/arm/boot/dts/imx6qdl.dtsi
index 06ec460..3e21e92 100644
--- a/arch/arm/boot/dts/imx6qdl.dtsi
+++ b/arch/arm/boot/dts/imx6qdl.dtsi
@@ -516,6 +516,7 @@
 				compatible = "fsl,imx6q-src";
 				reg = <0x020d8000 0x4000>;
 				interrupts = <0 91 0x04 0 96 0x04>;
+				#reset-cells = <1>;
 			};
 
 			gpc: gpc at 020dc000 {
@@ -795,6 +796,7 @@
 			interrupts = <0 6 0x4 0 5 0x4>;
 			clocks = <&clks 130>, <&clks 131>, <&clks 132>;
 			clock-names = "bus", "di0", "di1";
+			resets = <&src 2>;
 		};
 	};
 };
-- 
1.8.2.rc2

[PATCH v6 6/8] staging: drm/imx: Use SRC to reset IPU

[Philipp Zabel]

Request the System Reset Controller to reset the IPU if
specified via device tree phandle.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Marek Vasut <marex@denx.de>
---
 .../devicetree/bindings/staging/imx-drm/fsl-imx-drm.txt      |  3 +++
 drivers/staging/imx-drm/ipu-v3/ipu-common.c                  | 12 +++++++++---
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/staging/imx-drm/fsl-imx-drm.txt b/Documentation/devicetree/bindings/staging/imx-drm/fsl-imx-drm.txt
index 07654f0..f769857 100644
--- a/Documentation/devicetree/bindings/staging/imx-drm/fsl-imx-drm.txt
+++ b/Documentation/devicetree/bindings/staging/imx-drm/fsl-imx-drm.txt
@@ -8,6 +8,8 @@ Required properties:
 - interrupts: Should contain sync interrupt and error interrupt,
   in this order.
 - #crtc-cells: 1, See below
+- resets: phandle pointing to the system reset controller and
+          reset line index, see reset/fsl,imx-src.txt for details
 
 example:
 
@@ -16,6 +18,7 @@ ipu: ipu at 18000000 {
 	compatible = "fsl,imx53-ipu";
 	reg = <0x18000000 0x080000000>;
 	interrupts = <11 10>;
+	resets = <&src 2>;
 };
 
 Parallel display support
diff --git a/drivers/staging/imx-drm/ipu-v3/ipu-common.c b/drivers/staging/imx-drm/ipu-v3/ipu-common.c
index 366f259..04b8320 100644
--- a/drivers/staging/imx-drm/ipu-v3/ipu-common.c
+++ b/drivers/staging/imx-drm/ipu-v3/ipu-common.c
@@ -16,6 +16,7 @@
 #include <linux/export.h>
 #include <linux/types.h>
 #include <linux/init.h>
+#include <linux/reset.h>
 #include <linux/platform_device.h>
 #include <linux/err.h>
 #include <linux/spinlock.h>
@@ -660,7 +661,7 @@ int ipu_idmac_disable_channel(struct ipuv3_channel *channel)
 }
 EXPORT_SYMBOL_GPL(ipu_idmac_disable_channel);
 
-static int ipu_reset(struct ipu_soc *ipu)
+static int ipu_memory_reset(struct ipu_soc *ipu)
 {
 	unsigned long timeout;
 
@@ -1104,7 +1105,12 @@ static int ipu_probe(struct platform_device *pdev)
 	if (ret)
 		goto out_failed_irq;
 
-	ret = ipu_reset(ipu);
+	ret = device_reset(&pdev->dev);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to reset: %d\n", ret);
+		goto out_failed_reset;
+	}
+	ret = ipu_memory_reset(ipu);
 	if (ret)
 		goto out_failed_reset;
 
@@ -1130,8 +1136,8 @@ static int ipu_probe(struct platform_device *pdev)
 failed_add_clients:
 	ipu_submodules_exit(ipu);
 failed_submodules_init:
-	ipu_irq_exit(ipu);
 out_failed_reset:
+	ipu_irq_exit(ipu);
 out_failed_irq:
 	clk_disable_unprepare(ipu->clk);
 failed_clk_get:
-- 
1.8.2.rc2

[PATCH v6 7/8] ARM i.MX5: Add System Reset Controller (SRC) support for i.MX51 and i.MX53

[Philipp Zabel]

The SRC in i.MX51 and i.MX53 is similar to the one in i.MX6q minus
the IPU2 reset line and multi core CPU reset/enable bits.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Marek Vasut <marex@denx.de>
---
 arch/arm/boot/dts/imx6qdl.dtsi | 2 +-
 arch/arm/mach-imx/Kconfig      | 2 ++
 arch/arm/mach-imx/mm-imx5.c    | 2 ++
 arch/arm/mach-imx/src.c        | 4 +++-
 4 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/arm/boot/dts/imx6qdl.dtsi b/arch/arm/boot/dts/imx6qdl.dtsi
index 3e21e92..fb71499 100644
--- a/arch/arm/boot/dts/imx6qdl.dtsi
+++ b/arch/arm/boot/dts/imx6qdl.dtsi
@@ -513,7 +513,7 @@
 			};
 
 			src: src at 020d8000 {
-				compatible = "fsl,imx6q-src";
+				compatible = "fsl,imx6q-src", "fsl,imx51-src";
 				reg = <0x020d8000 0x4000>;
 				interrupts = <0 91 0x04 0 96 0x04>;
 				#reset-cells = <1>;
diff --git a/arch/arm/mach-imx/Kconfig b/arch/arm/mach-imx/Kconfig
index 5052e31..857c1fb 100644
--- a/arch/arm/mach-imx/Kconfig
+++ b/arch/arm/mach-imx/Kconfig
@@ -166,6 +166,7 @@ config	SOC_IMX51
 	bool
 	select ARCH_MX5
 	select ARCH_MX51
+	select HAVE_IMX_SRC
 	select PINCTRL
 	select PINCTRL_IMX51
 	select SOC_IMX5
@@ -793,6 +794,7 @@ config	SOC_IMX53
 	select ARCH_MX5
 	select ARCH_MX53
 	select HAVE_CAN_FLEXCAN if CAN
+	select HAVE_IMX_SRC
 	select IMX_HAVE_PLATFORM_IMX2_WDT
 	select PINCTRL
 	select PINCTRL_IMX53
diff --git a/arch/arm/mach-imx/mm-imx5.c b/arch/arm/mach-imx/mm-imx5.c
index cf34994..b7c4e70 100644
--- a/arch/arm/mach-imx/mm-imx5.c
+++ b/arch/arm/mach-imx/mm-imx5.c
@@ -84,6 +84,7 @@ void __init imx51_init_early(void)
 	mxc_set_cpu_type(MXC_CPU_MX51);
 	mxc_iomux_v3_init(MX51_IO_ADDRESS(MX51_IOMUXC_BASE_ADDR));
 	mxc_arch_reset_init(MX51_IO_ADDRESS(MX51_WDOG1_BASE_ADDR));
+	imx_src_init();
 }
 
 void __init imx53_init_early(void)
@@ -91,6 +92,7 @@ void __init imx53_init_early(void)
 	mxc_set_cpu_type(MXC_CPU_MX53);
 	mxc_iomux_v3_init(MX53_IO_ADDRESS(MX53_IOMUXC_BASE_ADDR));
 	mxc_arch_reset_init(MX53_IO_ADDRESS(MX53_WDOG1_BASE_ADDR));
+	imx_src_init();
 }
 
 void __init mx51_init_irq(void)
diff --git a/arch/arm/mach-imx/src.c b/arch/arm/mach-imx/src.c
index b50eee0..bc4d2c7 100644
--- a/arch/arm/mach-imx/src.c
+++ b/arch/arm/mach-imx/src.c
@@ -121,7 +121,9 @@ void __init imx_src_init(void)
 	struct device_node *np;
 	u32 val;
 
-	np = of_find_compatible_node(NULL, NULL, "fsl,imx6q-src");
+	np = of_find_compatible_node(NULL, NULL, "fsl,imx51-src");
+	if (!np)
+		return;
 	src_base = of_iomap(np, 0);
 	WARN_ON(!src_base);
 
-- 
1.8.2.rc2

[PATCH v6 8/8] ARM i.MX5: Add system reset controller (SRC) to i.MX51 and i.MX53 device tree

[Philipp Zabel]

Also, link SRC to IPU via phandle.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Marek Vasut <marex@denx.de>
---
 arch/arm/boot/dts/imx51.dtsi | 7 +++++++
 arch/arm/boot/dts/imx53.dtsi | 7 +++++++
 2 files changed, 14 insertions(+)

diff --git a/arch/arm/boot/dts/imx51.dtsi b/arch/arm/boot/dts/imx51.dtsi
index fcf035b..cfe4e92 100644
--- a/arch/arm/boot/dts/imx51.dtsi
+++ b/arch/arm/boot/dts/imx51.dtsi
@@ -67,6 +67,7 @@
 			compatible = "fsl,imx51-ipu";
 			reg = <0x40000000 0x20000000>;
 			interrupts = <11 10>;
+			resets = <&src 2>;
 		};
 
 		aips at 70000000 { /* AIPS1 */
@@ -501,6 +502,12 @@
 				status = "disabled";
 			};
 
+			src: src at 73fd0000 {
+				compatible = "fsl,imx51-src";
+				reg = <0x73fd0000 0x4000>;
+				#reset-cells = <1>;
+			};
+
 			clks: ccm at 73fd4000{
 				compatible = "fsl,imx51-ccm";
 				reg = <0x73fd4000 0x4000>;
diff --git a/arch/arm/boot/dts/imx53.dtsi b/arch/arm/boot/dts/imx53.dtsi
index d05aa21..9e1348d 100644
--- a/arch/arm/boot/dts/imx53.dtsi
+++ b/arch/arm/boot/dts/imx53.dtsi
@@ -72,6 +72,7 @@
 			compatible = "fsl,imx53-ipu";
 			reg = <0x18000000 0x080000000>;
 			interrupts = <11 10>;
+			resets = <&src 2>;
 		};
 
 		aips at 50000000 { /* AIPS1 */
@@ -558,6 +559,12 @@
 				status = "disabled";
 			};
 
+			src: src at 53fd0000 {
+				compatible = "fsl,imx53-src", "fsl,imx51-src";
+				reg = <0x53fd0000 0x4000>;
+				#reset-cells = <1>;
+			};
+
 			clks: ccm at 53fd4000{
 				compatible = "fsl,imx53-ccm";
 				reg = <0x53fd4000 0x4000>;
-- 
1.8.2.rc2

[PATCH v6 0/8] Reset controller API to reset IP modules on i.MX5 and i.MX6

[Arnd Bergmann]

On Thursday 28 March 2013, Philipp Zabel wrote:
> [Added Arnd and Greg to the recipients] I think the first three patches
> of this series are candidates to go through Arnd's tree. Arnd, would you
> take those patches?
>         [PATCH v6 1/8] dt: describe base reset signal binding
>         [PATCH v6 2/8] reset: Add reset controller API
>         [PATCH v6 3/8] reset: Add driver for gpio-controlled reset pins

Wow, very nice work. I had completely missed the series so far, as I'm
quite behind on reading mailing lists.

Yes, I can certainly take the three patches through arm-soc. Actually
I just handed over to Olof for now, but I'm assume he will also take
them when you send a pull request.

We also have at least one other platform (sirf/prima2) that will need
the subsystem in the near future. I'm probably stating the obvious here,
but  please make sure that the pull request you send for arm-soc uses
the exact git sha1 IDs that will be used for the follow-on patches
going through the platform trees.

	Arnd

[PATCH v6 0/8] Reset controller API to reset IP modules on i.MX5 and i.MX6

[Pavel Machek]

On Thu 2013-03-28 17:35:15, Philipp Zabel wrote:
> [Added Arnd and Greg to the recipients] I think the first three patches
> of this series are candidates to go through Arnd's tree. Arnd, would you
> take those patches?
>         [PATCH v6 1/8] dt: describe base reset signal binding
>         [PATCH v6 2/8] reset: Add reset controller API
>         [PATCH v6 3/8] reset: Add driver for gpio-controlled reset pins
> 
> The system reset controller (SRC) on i.MX51, i.MX53, and i.MX6q controls
> reset lines to the GPU, VPU, IPU, and OpenVG IP modules.
> 
> The following patches add a simple API for devices to request being reset
> by separate reset controller hardware and implements the reset signal
> device tree binding proposed by Stephen Warren. Contrary to Tegra hardware,
> the i.MX SRC contains self-deasserting reset registers, so I've included
> both ops to manually assert/deassert a reset line, as well as a "reset"
> operation that is supposed to assert the reset line and wait for it to
> deassert.
> 
> The i.MX SRC is enhanced to provide a reset controller and the IPU driver
> is made to request being reset by calling the device_reset(&pdev->dev)
> convenience wrapper during probing.
> 
> No changes since v5, I just reordered the series.

Reviewed-by: Pavel Machek <pavel@ucw.cz>

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

[PATCH v6 6/8] staging: drm/imx: Use SRC to reset IPU

[Greg Kroah-Hartman]

On Thu, Mar 28, 2013 at 05:35:21PM +0100, Philipp Zabel wrote:
> Request the System Reset Controller to reset the IPU if
> specified via device tree phandle.
> 
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> Reviewed-by: Stephen Warren <swarren@nvidia.com>
> Reviewed-by: Marek Vasut <marex@denx.de>
> ---
>  .../devicetree/bindings/staging/imx-drm/fsl-imx-drm.txt      |  3 +++
>  drivers/staging/imx-drm/ipu-v3/ipu-common.c                  | 12 +++++++++---
>  2 files changed, 12 insertions(+), 3 deletions(-)
> 

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[PATCH v6 0/8] Reset controller API to reset IP modules on i.MX5 and i.MX6

[Shawn Guo]

On Thu, Mar 28, 2013 at 10:07:54PM +0000, Arnd Bergmann wrote:
> On Thursday 28 March 2013, Philipp Zabel wrote:
> > [Added Arnd and Greg to the recipients] I think the first three patches
> > of this series are candidates to go through Arnd's tree. Arnd, would you
> > take those patches?
> >         [PATCH v6 1/8] dt: describe base reset signal binding
> >         [PATCH v6 2/8] reset: Add reset controller API
> >         [PATCH v6 3/8] reset: Add driver for gpio-controlled reset pins
> 
> Wow, very nice work. I had completely missed the series so far, as I'm
> quite behind on reading mailing lists.
> 
> Yes, I can certainly take the three patches through arm-soc. Actually
> I just handed over to Olof for now, but I'm assume he will also take
> them when you send a pull request.
> 
> We also have at least one other platform (sirf/prima2) that will need
> the subsystem in the near future. I'm probably stating the obvious here,
> but  please make sure that the pull request you send for arm-soc uses
> the exact git sha1 IDs that will be used for the follow-on patches
> going through the platform trees.

Ok, let me maintain a stable branch on IMX tree and forward the patches
to arm-soc, since the other patches in the series that I need to handle
will depend on the branch anyway.

Shawn

[PATCH v6 0/8] Reset controller API to reset IP modules on i.MX5 and i.MX6

[Shawn Guo]

On Thu, Mar 28, 2013 at 05:35:15PM +0100, Philipp Zabel wrote:
> The system reset controller (SRC) on i.MX51, i.MX53, and i.MX6q controls
> reset lines to the GPU, VPU, IPU, and OpenVG IP modules.
> 
> The following patches add a simple API for devices to request being reset
> by separate reset controller hardware and implements the reset signal
> device tree binding proposed by Stephen Warren. Contrary to Tegra hardware,
> the i.MX SRC contains self-deasserting reset registers, so I've included
> both ops to manually assert/deassert a reset line, as well as a "reset"
> operation that is supposed to assert the reset line and wait for it to
> deassert.
> 
> The i.MX SRC is enhanced to provide a reset controller and the IPU driver
> is made to request being reset by calling the device_reset(&pdev->dev)
> convenience wrapper during probing.
> 
> No changes since v5, I just reordered the series.

All applied, thanks.

[PATCH v6 1/8] dt: describe base reset signal binding

[Rob Herring]

On 03/28/2013 11:35 AM, Philipp Zabel wrote:
> From: Stephen Warren <swarren@nvidia.com>
> 
> This binding is intended to represent the hardware reset signals present
> internally in most IC (SoC, FPGA, ...) designs.
> It consists of a binding for a reset controller device (provider), and a
> pair of properties, "resets" and "reset-names", to link a device node
> (consumer) to its reset controller via phandle, similarly to the clock
> and interrupt bindings.
> 
> The reset controller has all information necessary to reset the consumer
> device. That could be provided via device tree, or it could be implemented
> in hardware.
> The aim is to enable device drivers to request a framework API to issue a
> reset simply by providing their struct device pointer as the most common
> case.
> 
> Signed-off-by: Stephen Warren <swarren@nvidia.com>
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
> Reviewed-by: Marek Vasut <marex@denx.de>

Looks good.

Acked-by: Rob Herring <rob.herring@calxeda.com>

Rob

> ---
>  Documentation/devicetree/bindings/reset/reset.txt | 75 +++++++++++++++++++++++
>  1 file changed, 75 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/reset/reset.txt
> 
> diff --git a/Documentation/devicetree/bindings/reset/reset.txt b/Documentation/devicetree/bindings/reset/reset.txt
> new file mode 100644
> index 0000000..31db6ff
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/reset/reset.txt
> @@ -0,0 +1,75 @@
> += Reset Signal Device Tree Bindings =
> +
> +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.
> +
> +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
> +reset consumer (the module being reset, or a module managing when a sub-
> +ordinate module is reset). This binding exists to represent the provider and
> +consumer, and provide a way to couple the two together.
> +
> +A reset signal is represented by the phandle of the provider, plus a reset
> +specifier - a list of DT cells that represents the reset signal within the
> +provider. The length (number of cells) and semantics of the reset specifier
> +are dictated by the binding of the reset provider, although common schemes
> +are described below.
> +
> +A word on where to place reset signal consumers in device tree: It is possible
> +in hardware for a reset signal to affect multiple logically separate HW blocks
> +at once. In this case, it would be unwise to represent this reset signal in
> +the DT node of each affected HW block, since if activated, an unrelated block
> +may be reset. Instead, reset signals should be represented in the DT node
> +where it makes most sense to control it; this may be a bus node if all
> +children of the bus are affected by the reset signal, or an individual HW
> +block node for dedicated reset signals. The intent of this binding is to give
> +appropriate software access to the reset signals in order to manage the HW,
> +rather than to slavishly enumerate the reset signal that affects each HW
> +block.
> +
> += Reset providers =
> +
> +Required properties:
> +#reset-cells:	Number of cells in a reset specifier; Typically 0 for nodes
> +		with a single reset output and 1 for nodes with multiple
> +		reset outputs.
> +
> +For example:
> +
> +	rst: reset-controller {
> +		#reset-cells = <1>;
> +	};
> +
> += Reset consumers =
> +
> +Required properties:
> +resets:		List of phandle and reset specifier pairs, one pair
> +		for each reset signal that affects the device, or that the
> +		device manages. Note: if the reset provider specifies '0' for
> +		#reset-cells, then only the phandle portion of the pair will
> +		appear.
> +
> +Optional properties:
> +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.
> +
> +For example:
> +
> +	device {
> +		resets = <&rst 20>;
> +		reset-names = "reset";
> +	};
> +
> +This represents a device with a single reset signal named "reset".
> +
> +	bus {
> +		resets = <&rst 10> <&rst 11> <&rst 12> <&rst 11>;
> +		reset-names = "i2s1", "i2s2", "dma", "mixer";
> +	};
> +
> +This represents a bus that controls the reset signal of each of four sub-
> +ordinate devices. Consider for example a bus that fails to operate unless no
> +child device has reset asserted.
> 

[PATCH v6 1/8] dt: describe base reset signal binding

[Philipp Zabel]

Hi Rob,

Am Donnerstag, den 04.04.2013, 08:49 -0500 schrieb Rob Herring:
> On 03/28/2013 11:35 AM, Philipp Zabel wrote:
> > From: Stephen Warren <swarren@nvidia.com>
> > 
> > This binding is intended to represent the hardware reset signals present
> > internally in most IC (SoC, FPGA, ...) designs.
> > It consists of a binding for a reset controller device (provider), and a
> > pair of properties, "resets" and "reset-names", to link a device node
> > (consumer) to its reset controller via phandle, similarly to the clock
> > and interrupt bindings.
> > 
> > The reset controller has all information necessary to reset the consumer
> > device. That could be provided via device tree, or it could be implemented
> > in hardware.
> > The aim is to enable device drivers to request a framework API to issue a
> > reset simply by providing their struct device pointer as the most common
> > case.
> > 
> > Signed-off-by: Stephen Warren <swarren@nvidia.com>
> > Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> > Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
> > Reviewed-by: Marek Vasut <marex@denx.de>
> 
> Looks good.
> 
> Acked-by: Rob Herring <rob.herring@calxeda.com>

Thank you. I'll not add the Acked-by: line to the patch itself, if
that's ok, since Shawn already pulled it into his imx/soc branch.

regards
Philipp

[PATCH v6 3/8] reset: Add driver for gpio-controlled reset pins

[Olof Johansson]

Hi,

On Thu, Mar 28, 2013 at 9:35 AM, Philipp Zabel <p.zabel@pengutronix.de> wrote:
> This driver implements a reset controller device that toggles gpios
> connected to reset pins of peripheral ICs. The delay between assertion
> and de-assertion of the reset signal can be configured.
>
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> Reviewed-by: Stephen Warren <swarren@nvidia.com>
> Reviewed-by: Marek Vasut <marex@denx.de>
> Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
> ---
>  .../devicetree/bindings/reset/gpio-reset.txt       |  37 ++++
>  drivers/reset/Kconfig                              |  13 ++
>  drivers/reset/Makefile                             |   1 +
>  drivers/reset/gpio-reset.c                         | 208 +++++++++++++++++++++
>  4 files changed, 259 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/reset/gpio-reset.txt
>  create mode 100644 drivers/reset/gpio-reset.c
>
> diff --git a/Documentation/devicetree/bindings/reset/gpio-reset.txt b/Documentation/devicetree/bindings/reset/gpio-reset.txt
> new file mode 100644
> index 0000000..1f203eb
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/reset/gpio-reset.txt
> @@ -0,0 +1,37 @@
> +GPIO reset controller
> +=====================
> +
> +A GPIO reset controller controls a number of GPIOs that are connected
> +to reset pins of peripheral ICs.
> +
> +Please also refer to reset.txt in this directory for common reset
> +controller binding usage.
> +
> +Required properties:
> +- compatible: Should be "gpio-reset"
> +- reset-gpios: List of gpios used as reset lines. The gpio specifier for this
> +               property depends on the gpio controller that provides the gpio.
> +- #reset-cells: 1, see below
> +
> +Optional properties:
> +- reset-delays: List of delays in microseconds. The corresponding gpio reset
> +                line should be asserted for this duration to reset.
> +- initially-in-reset: List of integers. Zero if the initial state should be
> +                      a deasserted reset line, nonzero if the line should be
> +                      kept in reset.
> +
> +example:
> +
> +gpio_reset: gpio-reset {
> +       compatible = "gpio-reset";
> +       reset-gpios = <&gpio5 0 1>; /* active-low */
> +       reset-delays = <10000>; /* 10 ms */
> +       initially-in-reset: <1>;
> +       #reset-cells = <1>;
> +};

I find this binding that uses an array of GPIOs and their state to be
a bit awkward, especially if you compare it to something like the
simple gpio regulators that have a simpler one-to-one mapping.

Also, if you did one node per gpio you'd have a boolean property for
"initially-in-reset" which seems much more logical (i.e. the property
is either there, or it's not).

A couple of more comments:

> +config RESET_GPIO
> +       tristate "GPIO reset controller support"
> +       depends on GENERIC_GPIO
> +       help
> +         This driver provides support for reset lines that are controlled
> +         directly by GPIOs.
> +         The delay between assertion and de-assertion of the reset signal
> +         can be configured.

Can be configured how? And why would I care about that when I'm trying
to decide if I need to include this driver in my kernel configuration
or not? Seems like misplaced information.

Since this is a platform driver and not just an OF driver, shouldn't
you provide a way to specify the same configuration data through a
platform_data structure as well?


-Olof

[PATCH v6 3/8] reset: Add driver for gpio-controlled reset pins

[Philipp Zabel]

Hi Olof,

Am Donnerstag, den 11.04.2013, 03:35 -0700 schrieb Olof Johansson:
> Hi,
> 
> On Thu, Mar 28, 2013 at 9:35 AM, Philipp Zabel <p.zabel@pengutronix.de> wrote:
> > This driver implements a reset controller device that toggles gpios
> > connected to reset pins of peripheral ICs. The delay between assertion
> > and de-assertion of the reset signal can be configured.
> >
> > Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> > Reviewed-by: Stephen Warren <swarren@nvidia.com>
> > Reviewed-by: Marek Vasut <marex@denx.de>
> > Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
> > ---
> >  .../devicetree/bindings/reset/gpio-reset.txt       |  37 ++++
> >  drivers/reset/Kconfig                              |  13 ++
> >  drivers/reset/Makefile                             |   1 +
> >  drivers/reset/gpio-reset.c                         | 208 +++++++++++++++++++++
> >  4 files changed, 259 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/reset/gpio-reset.txt
> >  create mode 100644 drivers/reset/gpio-reset.c
> >
> > diff --git a/Documentation/devicetree/bindings/reset/gpio-reset.txt b/Documentation/devicetree/bindings/reset/gpio-reset.txt
> > new file mode 100644
> > index 0000000..1f203eb
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/reset/gpio-reset.txt
> > @@ -0,0 +1,37 @@
> > +GPIO reset controller
> > +=====================
> > +
> > +A GPIO reset controller controls a number of GPIOs that are connected
> > +to reset pins of peripheral ICs.
> > +
> > +Please also refer to reset.txt in this directory for common reset
> > +controller binding usage.
> > +
> > +Required properties:
> > +- compatible: Should be "gpio-reset"
> > +- reset-gpios: List of gpios used as reset lines. The gpio specifier for this
> > +               property depends on the gpio controller that provides the gpio.
> > +- #reset-cells: 1, see below
> > +
> > +Optional properties:
> > +- reset-delays: List of delays in microseconds. The corresponding gpio reset
> > +                line should be asserted for this duration to reset.
> > +- initially-in-reset: List of integers. Zero if the initial state should be
> > +                      a deasserted reset line, nonzero if the line should be
> > +                      kept in reset.
> > +
> > +example:
> > +
> > +gpio_reset: gpio-reset {
> > +       compatible = "gpio-reset";
> > +       reset-gpios = <&gpio5 0 1>; /* active-low */
> > +       reset-delays = <10000>; /* 10 ms */
> > +       initially-in-reset: <1>;
> > +       #reset-cells = <1>;
> > +};
> 
> I find this binding that uses an array of GPIOs and their state to be
> a bit awkward, especially if you compare it to something like the
> simple gpio regulators that have a simpler one-to-one mapping.
> 
> Also, if you did one node per gpio you'd have a boolean property for
> "initially-in-reset" which seems much more logical (i.e. the property
> is either there, or it's not).

Thank you for your comments. I agree, to a degree.
The initially-in-reset array is a bit weird, and in principle, there is
no reason to group different reset gpios into the same platform device.
The main difference to the gpio regulator is that that one registers
multiple gpios per regulator, but only one regulator per platform
device. Do you propose to make the reset-gpio driver strictly control
only one reset gpio per platform device? In that case, the
fixed-regulator probably is a better example. How about this:

    resets {
        compatible = "simple-bus";

        reset1: gpio-reset {
            compatible = "gpio-reset";
            reset-gpio = <&gpio5 0 1>; /* active-low */
            reset-delay = <10000>; /* 10 ms */
            initially-in-reset;
            #reset-cells = <0>;
        };

        reset2: gpio-reset {
            compatible = "gpio-reset";
            reset-gpio = <&gpio3 5 0>;
            /* no reset delay, consumer has to (de)assert manually */
            #reset-cells = <0>;
        };
    };

> A couple of more comments:
> 
> > +config RESET_GPIO
> > +       tristate "GPIO reset controller support"
> > +       depends on GENERIC_GPIO
> > +       help
> > +         This driver provides support for reset lines that are controlled
> > +         directly by GPIOs.
> > +         The delay between assertion and de-assertion of the reset signal
> > +         can be configured.
> 
> Can be configured how? And why would I care about that when I'm trying
> to decide if I need to include this driver in my kernel configuration
> or not? Seems like misplaced information.

Configured via device tree. I'll just drop the second sentence. The idea
was to point out once more that it's the reset driver that carries the
timing information, but this really isn't the best place.

> Since this is a platform driver and not just an OF driver, shouldn't
> you provide a way to specify the same configuration data through a
> platform_data structure as well?

Will there be new non-OF platforms for which this is even useful? I can
add platform data support, if you like.

regards
Philipp

[PATCH v6 3/8] reset: Add driver for gpio-controlled reset pins

[Stephen Warren]

On 04/11/2013 04:35 AM, Olof Johansson wrote:
> On Thu, Mar 28, 2013 at 9:35 AM, Philipp Zabel <p.zabel@pengutronix.de> wrote:
>> This driver implements a reset controller device that toggles gpios
>> connected to reset pins of peripheral ICs. The delay between assertion
>> and de-assertion of the reset signal can be configured.
...
> Since this is a platform driver and not just an OF driver, shouldn't
> you provide a way to specify the same configuration data through a
> platform_data structure as well?

I believe the only practical use-cases for this driver are /currently/
for device-tree platforms. Shouldn't we add the platform_data support
only when some platform actively uses it?

In the past when reviewing new drivers, I pushed for platform drivers to
always implement the platform_data structure up-front, and support using
that if present rather than "falling back" to DT. However, Grant then
shot that down saying that there was no point adding dead code...

(this will also feed into the discussion about simple-framebuffer, which
also only needs DT support right now, but could in theory be extended to
support platform_data in the future if somebody wants).

[PATCH v6 3/8] reset: Add driver for gpio-controlled reset pins

[Olof Johansson]

On Thu, Apr 11, 2013 at 8:54 AM, Stephen Warren <swarren@wwwdotorg.org> wrote:
> On 04/11/2013 04:35 AM, Olof Johansson wrote:
>> On Thu, Mar 28, 2013 at 9:35 AM, Philipp Zabel <p.zabel@pengutronix.de> wrote:
>>> This driver implements a reset controller device that toggles gpios
>>> connected to reset pins of peripheral ICs. The delay between assertion
>>> and de-assertion of the reset signal can be configured.
> ...
>> Since this is a platform driver and not just an OF driver, shouldn't
>> you provide a way to specify the same configuration data through a
>> platform_data structure as well?
>
> I believe the only practical use-cases for this driver are /currently/
> for device-tree platforms. Shouldn't we add the platform_data support
> only when some platform actively uses it?

Then the Kconfig needs to depend on OF in this case.

> In the past when reviewing new drivers, I pushed for platform drivers to
> always implement the platform_data structure up-front, and support using
> that if present rather than "falling back" to DT. However, Grant then
> shot that down saying that there was no point adding dead code...

Uh, ok. I don't care much either way but it somehow seems like it'll
be impopular to start adding a lot of new "depends on OF" drivers. I
might be wrong though.

> (this will also feed into the discussion about simple-framebuffer, which
> also only needs DT support right now, but could in theory be extended to
> support platform_data in the future if somebody wants).

Yeah, that's turning out to be a color preference discussion for
sheds, not very surprising.


-Olof