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0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * ARM System Control and Management Interface (ARM SCMI) reset driver
0004  *
0005  * Copyright (C) 2019-2021 ARM Ltd.
0006  */
0007 
0008 #include <linux/module.h>
0009 #include <linux/of.h>
0010 #include <linux/device.h>
0011 #include <linux/reset-controller.h>
0012 #include <linux/scmi_protocol.h>
0013 
0014 static const struct scmi_reset_proto_ops *reset_ops;
0015 
0016 /**
0017  * struct scmi_reset_data - reset controller information structure
0018  * @rcdev: reset controller entity
0019  * @ph: ARM SCMI protocol handle used for communication with system controller
0020  */
0021 struct scmi_reset_data {
0022     struct reset_controller_dev rcdev;
0023     const struct scmi_protocol_handle *ph;
0024 };
0025 
0026 #define to_scmi_reset_data(p)   container_of((p), struct scmi_reset_data, rcdev)
0027 #define to_scmi_handle(p)   (to_scmi_reset_data(p)->ph)
0028 
0029 /**
0030  * scmi_reset_assert() - assert device reset
0031  * @rcdev: reset controller entity
0032  * @id: ID of the reset to be asserted
0033  *
0034  * This function implements the reset driver op to assert a device's reset
0035  * using the ARM SCMI protocol.
0036  *
0037  * Return: 0 for successful request, else a corresponding error value
0038  */
0039 static int
0040 scmi_reset_assert(struct reset_controller_dev *rcdev, unsigned long id)
0041 {
0042     const struct scmi_protocol_handle *ph = to_scmi_handle(rcdev);
0043 
0044     return reset_ops->assert(ph, id);
0045 }
0046 
0047 /**
0048  * scmi_reset_deassert() - deassert device reset
0049  * @rcdev: reset controller entity
0050  * @id: ID of the reset to be deasserted
0051  *
0052  * This function implements the reset driver op to deassert a device's reset
0053  * using the ARM SCMI protocol.
0054  *
0055  * Return: 0 for successful request, else a corresponding error value
0056  */
0057 static int
0058 scmi_reset_deassert(struct reset_controller_dev *rcdev, unsigned long id)
0059 {
0060     const struct scmi_protocol_handle *ph = to_scmi_handle(rcdev);
0061 
0062     return reset_ops->deassert(ph, id);
0063 }
0064 
0065 /**
0066  * scmi_reset_reset() - reset the device
0067  * @rcdev: reset controller entity
0068  * @id: ID of the reset signal to be reset(assert + deassert)
0069  *
0070  * This function implements the reset driver op to trigger a device's
0071  * reset signal using the ARM SCMI protocol.
0072  *
0073  * Return: 0 for successful request, else a corresponding error value
0074  */
0075 static int
0076 scmi_reset_reset(struct reset_controller_dev *rcdev, unsigned long id)
0077 {
0078     const struct scmi_protocol_handle *ph = to_scmi_handle(rcdev);
0079 
0080     return reset_ops->reset(ph, id);
0081 }
0082 
0083 static const struct reset_control_ops scmi_reset_ops = {
0084     .assert     = scmi_reset_assert,
0085     .deassert   = scmi_reset_deassert,
0086     .reset      = scmi_reset_reset,
0087 };
0088 
0089 static int scmi_reset_probe(struct scmi_device *sdev)
0090 {
0091     struct scmi_reset_data *data;
0092     struct device *dev = &sdev->dev;
0093     struct device_node *np = dev->of_node;
0094     const struct scmi_handle *handle = sdev->handle;
0095     struct scmi_protocol_handle *ph;
0096 
0097     if (!handle)
0098         return -ENODEV;
0099 
0100     reset_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_RESET, &ph);
0101     if (IS_ERR(reset_ops))
0102         return PTR_ERR(reset_ops);
0103 
0104     data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
0105     if (!data)
0106         return -ENOMEM;
0107 
0108     data->rcdev.ops = &scmi_reset_ops;
0109     data->rcdev.owner = THIS_MODULE;
0110     data->rcdev.of_node = np;
0111     data->rcdev.nr_resets = reset_ops->num_domains_get(ph);
0112     data->ph = ph;
0113 
0114     return devm_reset_controller_register(dev, &data->rcdev);
0115 }
0116 
0117 static const struct scmi_device_id scmi_id_table[] = {
0118     { SCMI_PROTOCOL_RESET, "reset" },
0119     { },
0120 };
0121 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
0122 
0123 static struct scmi_driver scmi_reset_driver = {
0124     .name = "scmi-reset",
0125     .probe = scmi_reset_probe,
0126     .id_table = scmi_id_table,
0127 };
0128 module_scmi_driver(scmi_reset_driver);
0129 
0130 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
0131 MODULE_DESCRIPTION("ARM SCMI reset controller driver");
0132 MODULE_LICENSE("GPL v2");