/* * 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 #include #include #include #include #include #include #include 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; int gpio; int gpio_active_high; struct device_d *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. */ static 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]; } /** * 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; } list_add(&rcdev->list, &reset_controller_list); 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) { list_del(&rcdev->list); } 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) return 0; 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) return 0; if (rstc->gpio >= 0) return gpio_direction_output(rstc->gpio, rstc->gpio_active_high); 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) return 0; if (rstc->gpio >= 0) return gpio_direction_output(rstc->gpio, !rstc->gpio_active_high); if (rstc->rcdev->ops->deassert) return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id); return -ENOSYS; } EXPORT_SYMBOL_GPL(reset_control_deassert); /** * of_reset_control_get - Lookup and obtain a reference to a reset controller. * @node: 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. */ static struct reset_control *of_reset_control_get(struct device_node *node, const char *id) { struct reset_control *rstc = ERR_PTR(-ENODEV); struct reset_controller_dev *r, *rcdev; struct of_phandle_args args; int index = 0; int rstc_id; int ret; if (!of_get_property(node, "resets", NULL)) return NULL; if (id) index = of_property_match_string(node, "reset-names", id); ret = of_parse_phandle_with_args(node, "resets", "#reset-cells", index, &args); if (ret) return ERR_PTR(ret); rcdev = NULL; list_for_each_entry(r, &reset_controller_list, list) { if (args.np == r->of_node) { rcdev = r; break; } } if (!rcdev) { return ERR_PTR(-ENODEV); } rstc_id = rcdev->of_xlate(rcdev, &args); if (rstc_id < 0) return ERR_PTR(rstc_id); rstc = kzalloc(sizeof(*rstc), GFP_KERNEL); if (!rstc) return ERR_PTR(-ENOMEM); rstc->rcdev = rcdev; rstc->id = rstc_id; rstc->gpio = -ENODEV; return rstc; } static struct reset_control * gpio_reset_control_get(struct device_d *dev, const char *id) { struct reset_control *rc; int gpio; enum of_gpio_flags flags; if (id) return ERR_PTR(-EINVAL); if (!of_get_property(dev->device_node, "reset-gpios", NULL)) return NULL; gpio = of_get_named_gpio_flags(dev->device_node, "reset-gpios", 0, &flags); if (gpio < 0) return ERR_PTR(gpio); rc = xzalloc(sizeof(*rc)); rc->gpio = gpio; rc->gpio_active_high = !(flags & OF_GPIO_ACTIVE_LOW); return rc; } /** * 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_d *dev, const char *id) { struct reset_control *rstc; if (!dev) return ERR_PTR(-EINVAL); rstc = of_reset_control_get(dev->device_node, id); if (IS_ERR(rstc)) return ERR_CAST(rstc); /* * If there is no dedicated reset controller device, check if we have * a reset line controlled by a GPIO instead. */ if (!rstc) { rstc = gpio_reset_control_get(dev, id); if (IS_ERR(rstc)) return ERR_CAST(rstc); } if (!rstc) return NULL; rstc->dev = dev; 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_OR_NULL(rstc)) return; kfree(rstc); } EXPORT_SYMBOL_GPL(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_d *dev) { struct reset_control *rstc; int ret; rstc = reset_control_get(dev, NULL); if (IS_ERR(rstc)) { if (PTR_ERR(rstc) == -ENOENT) return 0; return PTR_ERR(rstc); } ret = reset_control_reset(rstc); reset_control_put(rstc); return ret; } EXPORT_SYMBOL_GPL(device_reset); int device_reset_us(struct device_d *dev, int us) { struct reset_control *rstc; int ret; rstc = reset_control_get(dev, NULL); if (IS_ERR(rstc)) { if (PTR_ERR(rstc) == -ENOENT) return 0; return PTR_ERR(rstc); } ret = reset_control_assert(rstc); if (ret) return ret; udelay(us); ret = reset_control_deassert(rstc); if (ret) return ret; reset_control_put(rstc); return ret; } EXPORT_SYMBOL_GPL(device_reset_us);