--- /dev/null
+/*
+ * Texas Instrument's System Control Interface (TI-SCI) reset driver
+ *
+ * Copyright (C) 2015-2017 Texas Instruments Incorporated - http://www.ti.com/
+ * Andrew F. Davis <afd@ti.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/idr.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/soc/ti/ti_sci_protocol.h>
+
+/**
+ * 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 <afd@ti.com>");
+MODULE_DESCRIPTION("TI System Control Interface (TI SCI) Reset driver");
+MODULE_LICENSE("GPL v2");
projects / GitHub / moto-9609 / android_kernel_motorola_exynos9610.git / commitdiff