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authorPhilipp Zabel <p.zabel@pengutronix.de>2012-11-19 17:23:13 +0100
committerPhilipp Zabel <p.zabel@pengutronix.de>2013-04-12 10:26:23 +0200
commit61fc41317666be400802ac793f47de816ef7bd57 (patch)
treeec7e7f11ca78aec2d861190c19279fb7653e64b9 /drivers/reset/core.c
parent4e11f848c65b1c87782cb232a6e3b47a9d4c1f98 (diff)
downloadlinux-stericsson-61fc41317666be400802ac793f47de816ef7bd57.tar.gz
reset: Add reset controller API
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>
Diffstat (limited to 'drivers/reset/core.c')
-rw-r--r--drivers/reset/core.c297
1 files changed, 297 insertions, 0 deletions
diff --git a/drivers/reset/core.c b/drivers/reset/core.c
new file mode 100644
index 000000000000..a258277959b4
--- /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);