diff options
| -rw-r--r-- | Documentation/devicetree/bindings/reset/reset.txt | 75 | ||||
| -rw-r--r-- | drivers/Kconfig | 2 | ||||
| -rw-r--r-- | drivers/Makefile | 3 | ||||
| -rw-r--r-- | drivers/reset/Kconfig | 13 | ||||
| -rw-r--r-- | drivers/reset/Makefile | 1 | ||||
| -rw-r--r-- | drivers/reset/core.c | 297 | ||||
| -rw-r--r-- | include/linux/reset-controller.h | 51 | ||||
| -rw-r--r-- | include/linux/reset.h | 17 |
8 files changed, 459 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/reset/reset.txt b/Documentation/devicetree/bindings/reset/reset.txt new file mode 100644 index 000000000000..31db6ff84908 --- /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. diff --git a/drivers/Kconfig b/drivers/Kconfig index 202fa6d051b9..847f8e31f3dd 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 dce39a95fa71..1a64c4cd9094 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-$(CONFIG_RESET_CONTROLLER) += reset/ + # tty/ comes before char/ so that the VT console is the boot-time # default. obj-y += tty/ diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig new file mode 100644 index 000000000000..c9d04f797862 --- /dev/null +++ b/drivers/reset/Kconfig @@ -0,0 +1,13 @@ +config ARCH_HAS_RESET_CONTROLLER + bool + +menuconfig RESET_CONTROLLER + bool "Reset Controller Support" + default y if ARCH_HAS_RESET_CONTROLLER + help + Generic Reset Controller support. + + This framework is designed to abstract reset handling of devices + via GPIOs or SoC-internal reset controller modules. + + If unsure, say no. diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile new file mode 100644 index 000000000000..1e2d83f2b995 --- /dev/null +++ b/drivers/reset/Makefile @@ -0,0 +1 @@ +obj-$(CONFIG_RESET_CONTROLLER) += core.o diff --git a/drivers/reset/core.c b/drivers/reset/core.c new file mode 100644 index 000000000000..d1b6089a0ef8 --- /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); diff --git a/include/linux/reset-controller.h b/include/linux/reset-controller.h new file mode 100644 index 000000000000..2f61311ae3e0 --- /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 000000000000..6082247feab1 --- /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 |
