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) 2019-2021 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 static const struct scmi_reset_proto_ops *reset_ops;
  15
  16 /**
  17  * struct scmi_reset_data - reset controller information structure
  18  * @rcdev: reset controller entity
  19  * @ph: ARM SCMI protocol handle used for communication with system controller
  20  */
  21 struct scmi_reset_data {
  22         struct reset_controller_dev rcdev;
  23         const struct scmi_protocol_handle *ph;
  24 };
  25
  26 #define to_scmi_reset_data(p)   container_of((p), struct scmi_reset_data, rcdev)
  27 #define to_scmi_handle(p)       (to_scmi_reset_data(p)->ph)
  28
  29 /**
  30  * scmi_reset_assert() - assert device reset
  31  * @rcdev: reset controller entity
  32  * @id: ID of the reset to be asserted
  33  *
  34  * This function implements the reset driver op to assert a device's reset
  35  * using the ARM SCMI protocol.
  36  *
  37  * Return: 0 for successful request, else a corresponding error value
  38  */
  39 static int
  40 scmi_reset_assert(struct reset_controller_dev *rcdev, unsigned long id)
  41 {
  42         const struct scmi_protocol_handle *ph = to_scmi_handle(rcdev);
  43
  44         return reset_ops->assert(ph, id);
  45 }
  46
  47 /**
  48  * scmi_reset_deassert() - deassert device reset
  49  * @rcdev: reset controller entity
  50  * @id: ID of the reset to be deasserted
  51  *
  52  * This function implements the reset driver op to deassert a device's reset
  53  * using the ARM SCMI protocol.
  54  *
  55  * Return: 0 for successful request, else a corresponding error value
  56  */
  57 static int
  58 scmi_reset_deassert(struct reset_controller_dev *rcdev, unsigned long id)
  59 {
  60         const struct scmi_protocol_handle *ph = to_scmi_handle(rcdev);
  61
  62         return reset_ops->deassert(ph, id);
  63 }
  64
  65 /**
  66  * scmi_reset_reset() - reset the device
  67  * @rcdev: reset controller entity
  68  * @id: ID of the reset signal to be reset(assert + deassert)
  69  *
  70  * This function implements the reset driver op to trigger a device's
  71  * reset signal using the ARM SCMI protocol.
  72  *
  73  * Return: 0 for successful request, else a corresponding error value
  74  */
  75 static int
  76 scmi_reset_reset(struct reset_controller_dev *rcdev, unsigned long id)
  77 {
  78         const struct scmi_protocol_handle *ph = to_scmi_handle(rcdev);
  79
  80         return reset_ops->reset(ph, id);
  81 }
  82
  83 static const struct reset_control_ops scmi_reset_ops = {
  84         .assert         = scmi_reset_assert,
  85         .deassert       = scmi_reset_deassert,
  86         .reset          = scmi_reset_reset,
  87 };
  88
  89 static int scmi_reset_probe(struct scmi_device *sdev)
  90 {
  91         struct scmi_reset_data *data;
  92         struct device *dev = &sdev->dev;
  93         struct device_node *np = dev->of_node;
  94         const struct scmi_handle *handle = sdev->handle;
  95         struct scmi_protocol_handle *ph;
  96
  97         if (!handle)
  98                 return -ENODEV;
  99
 100         reset_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_RESET, &ph);
 101         if (IS_ERR(reset_ops))
 102                 return PTR_ERR(reset_ops);
 103
 104         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 105         if (!data)
 106                 return -ENOMEM;
 107
 108         data->rcdev.ops = &scmi_reset_ops;
 109         data->rcdev.owner = THIS_MODULE;
 110         data->rcdev.of_node = np;
 111         data->rcdev.nr_resets = reset_ops->num_domains_get(ph);
 112         data->ph = ph;
 113
 114         return devm_reset_controller_register(dev, &data->rcdev);
 115 }
 116
 117 static const struct scmi_device_id scmi_id_table[] = {
 118         { SCMI_PROTOCOL_RESET, "reset" },
 119         { },
 120 };
 121 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
 122
 123 static struct scmi_driver scmi_reset_driver = {
 124         .name = "scmi-reset",
 125         .probe = scmi_reset_probe,
 126         .id_table = scmi_id_table,
 127 };
 128 module_scmi_driver(scmi_reset_driver);
 129
 130 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
 131 MODULE_DESCRIPTION("ARM SCMI reset controller driver");
 132 MODULE_LICENSE("GPL v2");