drivers/reset/reset-scmi.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * ARM System Control and Management Interface (ARM SCMI) reset driver
   4  *
   5  * Copyright (C) 2019 ARM Ltd.
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/of.h>
  10 #include <linux/device.h>
  11 #include <linux/reset-controller.h>
  12 #include <linux/scmi_protocol.h>
  13
  14 /**
  15  * struct scmi_reset_data - reset controller information structure
  16  * @rcdev: reset controller entity
  17  * @handle: ARM SCMI handle used for communication with system controller
  18  */
  19 struct scmi_reset_data {
  20         struct reset_controller_dev rcdev;
  21         const struct scmi_handle *handle;
  22 };
  23
  24 #define to_scmi_reset_data(p)   container_of((p), struct scmi_reset_data, rcdev)
  25 #define to_scmi_handle(p)       (to_scmi_reset_data(p)->handle)
  26
  27 /**
  28  * scmi_reset_assert() - assert device reset
  29  * @rcdev: reset controller entity
  30  * @id: ID of the reset to be asserted
  31  *
  32  * This function implements the reset driver op to assert a device's reset
  33  * using the ARM SCMI protocol.
  34  *
  35  * Return: 0 for successful request, else a corresponding error value
  36  */
  37 static int
  38 scmi_reset_assert(struct reset_controller_dev *rcdev, unsigned long id)
  39 {
  40         const struct scmi_handle *handle = to_scmi_handle(rcdev);
  41
  42         return handle->reset_ops->assert(handle, id);
  43 }
  44
  45 /**
  46  * scmi_reset_deassert() - deassert device reset
  47  * @rcdev: reset controller entity
  48  * @id: ID of the reset to be deasserted
  49  *
  50  * This function implements the reset driver op to deassert a device's reset
  51  * using the ARM SCMI protocol.
  52  *
  53  * Return: 0 for successful request, else a corresponding error value
  54  */
  55 static int
  56 scmi_reset_deassert(struct reset_controller_dev *rcdev, unsigned long id)
  57 {
  58         const struct scmi_handle *handle = to_scmi_handle(rcdev);
  59
  60         return handle->reset_ops->deassert(handle, id);
  61 }
  62
  63 /**
  64  * scmi_reset_reset() - reset the device
  65  * @rcdev: reset controller entity
  66  * @id: ID of the reset signal to be reset(assert + deassert)
  67  *
  68  * This function implements the reset driver op to trigger a device's
  69  * reset signal using the ARM SCMI protocol.
  70  *
  71  * Return: 0 for successful request, else a corresponding error value
  72  */
  73 static int
  74 scmi_reset_reset(struct reset_controller_dev *rcdev, unsigned long id)
  75 {
  76         const struct scmi_handle *handle = to_scmi_handle(rcdev);
  77
  78         return handle->reset_ops->reset(handle, id);
  79 }
  80
  81 static const struct reset_control_ops scmi_reset_ops = {
  82         .assert         = scmi_reset_assert,
  83         .deassert       = scmi_reset_deassert,
  84         .reset          = scmi_reset_reset,
  85 };
  86
  87 static int scmi_reset_probe(struct scmi_device *sdev)
  88 {
  89         struct scmi_reset_data *data;
  90         struct device *dev = &sdev->dev;
  91         struct device_node *np = dev->of_node;
  92         const struct scmi_handle *handle = sdev->handle;
  93
  94         if (!handle || !handle->reset_ops)
  95                 return -ENODEV;
  96
  97         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
  98         if (!data)
  99                 return -ENOMEM;
 100
 101         data->rcdev.ops = &scmi_reset_ops;
 102         data->rcdev.owner = THIS_MODULE;
 103         data->rcdev.of_node = np;
 104         data->rcdev.nr_resets = handle->reset_ops->num_domains_get(handle);
 105         data->handle = handle;
 106
 107         return devm_reset_controller_register(dev, &data->rcdev);
 108 }
 109
 110 static const struct scmi_device_id scmi_id_table[] = {
 111         { SCMI_PROTOCOL_RESET, "reset" },
 112         { },
 113 };
 114 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
 115
 116 static struct scmi_driver scmi_reset_driver = {
 117         .name = "scmi-reset",
 118         .probe = scmi_reset_probe,
 119         .id_table = scmi_id_table,
 120 };
 121 module_scmi_driver(scmi_reset_driver);
 122
 123 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
 124 MODULE_DESCRIPTION("ARM SCMI reset controller driver");
 125 MODULE_LICENSE("GPL v2");