[PATCH v2 2/8] reset: Add reset controller API
Philipp Zabel
p.zabel at pengutronix.de
Thu Feb 14 04:34:26 EST 2013
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 at pengutronix.de>
Reviewed-by: Stephen Warren <swarren at nvidia.com>
---
Changes since v1:
- Added missing header files.
- Fixed reset_controller_register comment.
- Added missing reset_controller_unregister.
- Made reset_control_reset/assert/deassert return -ENOSYS
if not implemented by the reset controller driver.
- Fixed reset_control_put to not access rstc after freeing it.
- Whitespace fixes
---
drivers/Kconfig | 2 +
drivers/Makefile | 3 +
drivers/reset/Kconfig | 9 ++
drivers/reset/Makefile | 1 +
drivers/reset/core.c | 238 ++++++++++++++++++++++++++++++++++++++
include/linux/reset-controller.h | 39 +++++++
include/linux/reset.h | 17 +++
7 files changed, 309 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 4af933d..682fb7c 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -42,6 +42,9 @@ ifndef CONFIG_ARCH_USES_GETTIMEOFFSET
obj-y += clocksource/
endif
+# reset controllers early, since gpu drivers might rely on them to initialize
+obj-$(CONFIG_RESET_CONTROLLER) += reset/
+
# tty/ comes before char/ so that the VT console is the boot-time
# default.
obj-y += tty/
diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
new file mode 100644
index 0000000..66ac385
--- /dev/null
+++ b/drivers/reset/Kconfig
@@ -0,0 +1,9 @@
+menuconfig RESET_CONTROLLER
+ bool "Reset Controller Support"
+ help
+ Generic Reset Controller support.
+
+ This framework is designed to abstract reset handling of devices
+ via GPIOs or SoC-internal reset controller modules.
+
+ If unsure, say no.
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
new file mode 100644
index 0000000..1e2d83f
--- /dev/null
+++ b/drivers/reset/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_RESET_CONTROLLER) += core.o
diff --git a/drivers/reset/core.c b/drivers/reset/core.c
new file mode 100644
index 0000000..468f831
--- /dev/null
+++ b/drivers/reset/core.c
@@ -0,0 +1,238 @@
+#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
+ *
+ * @id: ID of the reset controller in the reset
+ * controller device
+ */
+struct reset_control {
+ struct reset_controller_dev *rcdev;
+ unsigned int id;
+};
+
+/**
+ * reset_controller_register - register a reset controller device
+ *
+ * @rcdev: a pointer to struct reset_controller_dev
+ */
+int reset_controller_register(struct reset_controller_dev *rcdev)
+{
+ mutex_lock(&reset_controller_list_mutex);
+ list_add(&rcdev->list, &reset_controller_list);
+ mutex_unlock(&reset_controller_list_mutex);
+
+ return 0;
+}
+
+/**
+ * reset_controller_unregister - unregister a reset controller device
+ *
+ * @rcdev: a pointer to struct reset_controller_dev
+ */
+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);
+}
+
+/**
+ * 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 device_node *rcdev_node;
+ struct of_phandle_args args;
+ int rcdev_index;
+ int ret;
+ int i;
+
+ if (!dev)
+ return ERR_PTR(-EINVAL);
+
+ rcdev_node = NULL;
+ for (i = 0; rcdev_node == NULL; i++) {
+ ret = of_parse_phandle_with_args(dev->of_node, "resets",
+ "#reset-cells", i, &args);
+ if (ret)
+ return ERR_PTR(ret);
+ of_node_put(args.np);
+ if (args.args_count <= 0)
+ return ERR_PTR(-EINVAL);
+
+ if (id) {
+ const char *reset_name;
+ ret = of_property_read_string_index(dev->of_node,
+ "reset-names", i,
+ &reset_name);
+ if (ret)
+ return ERR_PTR(ret);
+ if (strcmp(id, reset_name) != 0)
+ continue;
+ }
+
+ rcdev_index = args.args[0];
+ rcdev_node = args.np;
+ break;
+ }
+
+ mutex_lock(&reset_controller_list_mutex);
+ rcdev = NULL;
+ list_for_each_entry(r, &reset_controller_list, list) {
+ if (rcdev_node == r->of_node) {
+ rcdev = r;
+ break;
+ }
+ }
+ mutex_unlock(&reset_controller_list_mutex);
+
+ if (!rcdev)
+ return ERR_PTR(-ENODEV);
+
+ try_module_get(rcdev->owner);
+
+ rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
+ if (!rstc)
+ return ERR_PTR(-ENOMEM);
+
+ rstc->rcdev = rcdev;
+ rstc->id = rcdev_index;
+
+ return rstc;
+}
+EXPORT_SYMBOL_GPL(reset_control_get);
+
+/**
+ * reset_control_put - free the reset controller
+ * @reset: 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);
+
+/**
+ * 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);
+
+ kfree(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..4d38aa3
--- /dev/null
+++ b/include/linux/reset-controller.h
@@ -0,0 +1,39 @@
+#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 - reset controller entity that might
+ * provide multiple reset controls
+ */
+struct reset_controller_dev {
+ struct reset_control_ops *ops;
+ struct module *owner;
+ struct list_head list;
+ struct device_node *of_node;
+};
+
+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..c4119c5
--- /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_controlr_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
--
1.7.10.4
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