// SPDX-License-Identifier: GPL-2.0-only /* * Texas Instrument's System Control Interface (TI-SCI) reset driver * * Copyright (C) 2015-2017 Texas Instruments Incorporated - https://www.ti.com/ * Andrew F. Davis */ #include #include #include #include #include #include #include /** * struct ti_sci_reset_control - reset control structure * @dev_id: SoC-specific device identifier * @reset_mask: reset mask to use for toggling reset * @lock: synchronize reset_mask read-modify-writes */ struct ti_sci_reset_control { u32 dev_id; u32 reset_mask; struct mutex lock; }; /** * struct ti_sci_reset_data - reset controller information structure * @rcdev: reset controller entity * @dev: reset controller device pointer * @sci: TI SCI handle used for communication with system controller * @idr: idr structure for mapping ids to reset control structures */ struct ti_sci_reset_data { struct reset_controller_dev rcdev; struct device *dev; const struct ti_sci_handle *sci; struct idr idr; }; #define to_ti_sci_reset_data(p) \ container_of((p), struct ti_sci_reset_data, rcdev) /** * ti_sci_reset_set() - program a device's reset * @rcdev: reset controller entity * @id: ID of the reset to toggle * @assert: boolean flag to indicate assert or deassert * * This is a common internal function used to assert or deassert a device's * reset using the TI SCI protocol. The device's reset is asserted if the * @assert argument is true, or deasserted if @assert argument is false. * The mechanism itself is a read-modify-write procedure, the current device * reset register is read using a TI SCI device operation, the new value is * set or un-set using the reset's mask, and the new reset value written by * using another TI SCI device operation. * * Return: 0 for successful request, else a corresponding error value */ static int ti_sci_reset_set(struct reset_controller_dev *rcdev, unsigned long id, bool assert) { struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev); const struct ti_sci_handle *sci = data->sci; const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops; struct ti_sci_reset_control *control; u32 reset_state; int ret; control = idr_find(&data->idr, id); if (!control) return -EINVAL; mutex_lock(&control->lock); ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state); if (ret) goto out; if (assert) reset_state |= control->reset_mask; else reset_state &= ~control->reset_mask; ret = dev_ops->set_device_resets(sci, control->dev_id, reset_state); out: mutex_unlock(&control->lock); return ret; } /** * ti_sci_reset_assert() - assert device reset * @rcdev: reset controller entity * @id: ID of the reset to be asserted * * This function implements the reset driver op to assert a device's reset * using the TI SCI protocol. This invokes the function ti_sci_reset_set() * with the corresponding parameters as passed in, but with the @assert * argument set to true for asserting the reset. * * Return: 0 for successful request, else a corresponding error value */ static int ti_sci_reset_assert(struct reset_controller_dev *rcdev, unsigned long id) { return ti_sci_reset_set(rcdev, id, true); } /** * ti_sci_reset_deassert() - deassert device reset * @rcdev: reset controller entity * @id: ID of the reset to be deasserted * * This function implements the reset driver op to deassert a device's reset * using the TI SCI protocol. This invokes the function ti_sci_reset_set() * with the corresponding parameters as passed in, but with the @assert * argument set to false for deasserting the reset. * * Return: 0 for successful request, else a corresponding error value */ static int ti_sci_reset_deassert(struct reset_controller_dev *rcdev, unsigned long id) { return ti_sci_reset_set(rcdev, id, false); } /** * ti_sci_reset_status() - check device reset status * @rcdev: reset controller entity * @id: ID of reset to be checked * * This function implements the reset driver op to return the status of a * device's reset using the TI SCI protocol. The reset register value is read * by invoking the TI SCI device operation .get_device_resets(), and the * status of the specific reset is extracted and returned using this reset's * reset mask. * * Return: 0 if reset is deasserted, or a non-zero value if reset is asserted */ static int ti_sci_reset_status(struct reset_controller_dev *rcdev, unsigned long id) { struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev); const struct ti_sci_handle *sci = data->sci; const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops; struct ti_sci_reset_control *control; u32 reset_state; int ret; control = idr_find(&data->idr, id); if (!control) return -EINVAL; ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state); if (ret) return ret; return reset_state & control->reset_mask; } static const struct reset_control_ops ti_sci_reset_ops = { .assert = ti_sci_reset_assert, .deassert = ti_sci_reset_deassert, .status = ti_sci_reset_status, }; /** * ti_sci_reset_of_xlate() - translate a set of OF arguments to a reset ID * @rcdev: reset controller entity * @reset_spec: OF reset argument specifier * * This function performs the translation of the reset argument specifier * values defined in a reset consumer device node. The function allocates a * reset control structure for that device reset, and will be used by the * driver for performing any reset functions on that reset. An idr structure * is allocated and used to map to the reset control structure. This idr * is used by the driver to do reset lookups. * * Return: 0 for successful request, else a corresponding error value */ static int ti_sci_reset_of_xlate(struct reset_controller_dev *rcdev, const struct of_phandle_args *reset_spec) { struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev); struct ti_sci_reset_control *control; if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells)) return -EINVAL; control = devm_kzalloc(data->dev, sizeof(*control), GFP_KERNEL); if (!control) return -ENOMEM; control->dev_id = reset_spec->args[0]; control->reset_mask = reset_spec->args[1]; mutex_init(&control->lock); return idr_alloc(&data->idr, control, 0, 0, GFP_KERNEL); } static const struct of_device_id ti_sci_reset_of_match[] = { { .compatible = "ti,sci-reset", }, { /* sentinel */ }, }; MODULE_DEVICE_TABLE(of, ti_sci_reset_of_match); static int ti_sci_reset_probe(struct platform_device *pdev) { struct ti_sci_reset_data *data; if (!pdev->dev.of_node) return -ENODEV; data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); if (!data) return -ENOMEM; data->sci = devm_ti_sci_get_handle(&pdev->dev); if (IS_ERR(data->sci)) return PTR_ERR(data->sci); data->rcdev.ops = &ti_sci_reset_ops; data->rcdev.owner = THIS_MODULE; data->rcdev.of_node = pdev->dev.of_node; data->rcdev.of_reset_n_cells = 2; data->rcdev.of_xlate = ti_sci_reset_of_xlate; data->dev = &pdev->dev; idr_init(&data->idr); platform_set_drvdata(pdev, data); return reset_controller_register(&data->rcdev); } static int ti_sci_reset_remove(struct platform_device *pdev) { struct ti_sci_reset_data *data = platform_get_drvdata(pdev); reset_controller_unregister(&data->rcdev); idr_destroy(&data->idr); return 0; } static struct platform_driver ti_sci_reset_driver = { .probe = ti_sci_reset_probe, .remove = ti_sci_reset_remove, .driver = { .name = "ti-sci-reset", .of_match_table = ti_sci_reset_of_match, }, }; module_platform_driver(ti_sci_reset_driver); MODULE_AUTHOR("Andrew F. Davis "); MODULE_DESCRIPTION("TI System Control Interface (TI SCI) Reset driver"); MODULE_LICENSE("GPL v2");