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openwrt-owl/target/linux/ramips/patches-3.9/0154-reset-Add-reset-contro...

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From d6cfbdfa001891894efe078a49ad82ac8a932dbb Mon Sep 17 00:00:00 2001
From: John Crispin <blogic@openwrt.org>
Date: Mon, 20 May 2013 15:42:01 +0200
Subject: [PATCH 154/164] reset: Add reset controller API
backport from v3.10-rc1
61fc41317666be400802ac793f47de816ef7bd57
6034bb22d8387708075c083385e5d2e1072a4f33
4e11f848c65b1c87782cb232a6e3b47a9d4c1f98
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>
Reviewed-by: Pavel Machek <pavel@ucw.cz>
---
Documentation/devicetree/bindings/reset/reset.txt | 75 ++++++
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 ++
8 files changed, 459 insertions(+)
create mode 100644 Documentation/devicetree/bindings/reset/reset.txt
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
--- /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.
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -164,4 +164,6 @@ source "drivers/irqchip/Kconfig"
source "drivers/ipack/Kconfig"
+source "drivers/reset/Kconfig"
+
endmenu
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -38,6 +38,9 @@ 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-$(CONFIG_RESET_CONTROLLER) += reset/
+
# tty/ comes before char/ so that the VT console is the boot-time
# default.
obj-y += tty/
--- /dev/null
+++ b/drivers/reset/Kconfig
@@ -0,0 +1,13 @@
+config ARCH_HAS_RESET_CONTROLLER
+ bool
+
+menuconfig RESET_CONTROLLER
+ bool "Reset Controller Support"
+ default y if ARCH_HAS_RESET_CONTROLLER
+ help
+ Generic Reset Controller support.
+
+ This framework is designed to abstract reset handling of devices
+ via GPIOs or SoC-internal reset controller modules.
+
+ If unsure, say no.
--- /dev/null
+++ b/drivers/reset/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_RESET_CONTROLLER) += core.o
--- /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(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);
--- /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
--- /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
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