/* * 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/atomic.h> #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_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 * @list: list entry for the rcdev's reset controller list * @id: ID of the reset controller in the reset * controller device * @refcnt: Number of gets of this reset_control * @shared: Is this a shared (1), or an exclusive (0) reset_control? * @deassert_cnt: Number of times this reset line has been deasserted */ struct reset_control { struct reset_controller_dev *rcdev; struct list_head list; unsigned int id; unsigned int refcnt; int shared; atomic_t deassert_count; }; /** * 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. */ static int of_reset_simple_xlate(struct reset_controller_dev *rcdev, const struct of_phandle_args *reset_spec) { if (reset_spec->args[0] >= rcdev->nr_resets) return -EINVAL; return reset_spec->args[0]; } /** * 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; } INIT_LIST_HEAD(&rcdev->reset_control_head); mutex_lock(&reset_list_mutex); list_add(&rcdev->list, &reset_controller_list); mutex_unlock(&reset_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_list_mutex); list_del(&rcdev->list); mutex_unlock(&reset_list_mutex); } EXPORT_SYMBOL_GPL(reset_controller_unregister); static void devm_reset_controller_release(struct device *dev, void *res) { reset_controller_unregister(*(struct reset_controller_dev **)res); } /** * devm_reset_controller_register - resource managed reset_controller_register() * @dev: device that is registering this reset controller * @rcdev: a pointer to the initialized reset controller device * * Managed reset_controller_register(). For reset controllers registered by * this function, reset_controller_unregister() is automatically called on * driver detach. See reset_controller_register() for more information. */ int devm_reset_controller_register(struct device *dev, struct reset_controller_dev *rcdev) { struct reset_controller_dev **rcdevp; int ret; rcdevp = devres_alloc(devm_reset_controller_release, sizeof(*rcdevp), GFP_KERNEL); if (!rcdevp) return -ENOMEM; ret = reset_controller_register(rcdev); if (!ret) { *rcdevp = rcdev; devres_add(dev, rcdevp); } else { devres_free(rcdevp); } return ret; } EXPORT_SYMBOL_GPL(devm_reset_controller_register); /** * reset_control_reset - reset the controlled device * @rstc: reset controller * * Calling this on a shared reset controller is an error. */ int reset_control_reset(struct reset_control *rstc) { if (WARN_ON(IS_ERR_OR_NULL(rstc)) || WARN_ON(rstc->shared)) return -EINVAL; if (rstc->rcdev->ops->reset) return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id); return -ENOTSUPP; } EXPORT_SYMBOL_GPL(reset_control_reset); /** * reset_control_assert - asserts the reset line * @rstc: reset controller * * Calling this on an exclusive reset controller guarantees that the reset * will be asserted. When called on a shared reset controller the line may * still be deasserted, as long as other users keep it so. * * For shared reset controls a driver cannot expect the hw's registers and * internal state to be reset, but must be prepared for this to happen. */ int reset_control_assert(struct reset_control *rstc) { if (WARN_ON(IS_ERR_OR_NULL(rstc))) return -EINVAL; if (!rstc->rcdev->ops->assert) return -ENOTSUPP; if (rstc->shared) { if (WARN_ON(atomic_read(&rstc->deassert_count) == 0)) return -EINVAL; if (atomic_dec_return(&rstc->deassert_count) != 0) return 0; } return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id); } EXPORT_SYMBOL_GPL(reset_control_assert); /** * reset_control_deassert - deasserts the reset line * @rstc: reset controller * * After calling this function, the reset is guaranteed to be deasserted. */ int reset_control_deassert(struct reset_control *rstc) { if (WARN_ON(IS_ERR_OR_NULL(rstc))) return -EINVAL; if (!rstc->rcdev->ops->deassert) return -ENOTSUPP; if (rstc->shared) { if (atomic_inc_return(&rstc->deassert_count) != 1) return 0; } return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id); } EXPORT_SYMBOL_GPL(reset_control_deassert); /** * reset_control_status - returns a negative errno if not supported, a * positive value if the reset line is asserted, or zero if the reset * line is not asserted. * @rstc: reset controller */ int reset_control_status(struct reset_control *rstc) { if (WARN_ON(IS_ERR_OR_NULL(rstc))) return -EINVAL; if (rstc->rcdev->ops->status) return rstc->rcdev->ops->status(rstc->rcdev, rstc->id); return -ENOTSUPP; } EXPORT_SYMBOL_GPL(reset_control_status); static struct reset_control *__reset_control_get( struct reset_controller_dev *rcdev, unsigned int index, int shared) { struct reset_control *rstc; lockdep_assert_held(&reset_list_mutex); list_for_each_entry(rstc, &rcdev->reset_control_head, list) { if (rstc->id == index) { if (WARN_ON(!rstc->shared || !shared)) return ERR_PTR(-EBUSY); rstc->refcnt++; return rstc; } } rstc = kzalloc(sizeof(*rstc), GFP_KERNEL); if (!rstc) return ERR_PTR(-ENOMEM); try_module_get(rcdev->owner); rstc->rcdev = rcdev; list_add(&rstc->list, &rcdev->reset_control_head); rstc->id = index; rstc->refcnt = 1; rstc->shared = shared; return rstc; } static void __reset_control_put(struct reset_control *rstc) { lockdep_assert_held(&reset_list_mutex); if (--rstc->refcnt) return; module_put(rstc->rcdev->owner); list_del(&rstc->list); kfree(rstc); } struct reset_control *__of_reset_control_get(struct device_node *node, const char *id, int index, int shared) { struct reset_control *rstc; struct reset_controller_dev *r, *rcdev; struct of_phandle_args args; int rstc_id; int ret; if (!node) return ERR_PTR(-EINVAL); if (id) { index = of_property_match_string(node, "reset-names", id); if (index < 0) return ERR_PTR(-ENOENT); } ret = of_parse_phandle_with_args(node, "resets", "#reset-cells", index, &args); if (ret) return ERR_PTR(ret); mutex_lock(&reset_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_list_mutex); return ERR_PTR(-EPROBE_DEFER); } if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) { mutex_unlock(&reset_list_mutex); return ERR_PTR(-EINVAL); } rstc_id = rcdev->of_xlate(rcdev, &args); if (rstc_id < 0) { mutex_unlock(&reset_list_mutex); return ERR_PTR(rstc_id); } /* reset_list_mutex also protects the rcdev's reset_control list */ rstc = __reset_control_get(rcdev, rstc_id, shared); mutex_unlock(&reset_list_mutex); return rstc; } EXPORT_SYMBOL_GPL(__of_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; mutex_lock(&reset_list_mutex); __reset_control_put(rstc); mutex_unlock(&reset_list_mutex); } EXPORT_SYMBOL_GPL(reset_control_put); static void devm_reset_control_release(struct device *dev, void *res) { reset_control_put(*(struct reset_control **)res); } struct reset_control *__devm_reset_control_get(struct device *dev, const char *id, int index, int shared) { struct reset_control **ptr, *rstc; ptr = devres_alloc(devm_reset_control_release, sizeof(*ptr), GFP_KERNEL); if (!ptr) return ERR_PTR(-ENOMEM); rstc = __of_reset_control_get(dev ? dev->of_node : NULL, id, index, shared); 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); reset_control_put(rstc); return ret; } EXPORT_SYMBOL_GPL(device_reset);