drivers/reset/reset-ti-sci.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Texas Instrument's System Control Interface (TI-SCI) reset driver
   4  *
   5  * Copyright (C) 2015-2017 Texas Instruments Incorporated - https://www.ti.com/
   6  *      Andrew F. Davis <afd@ti.com>
   7  */
   8
   9 #include <linux/idr.h>
  10 #include <linux/module.h>
  11 #include <linux/mutex.h>
  12 #include <linux/of.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/reset-controller.h>
  15 #include <linux/soc/ti/ti_sci_protocol.h>
  16
  17 /**
  18  * struct ti_sci_reset_control - reset control structure
  19  * @dev_id: SoC-specific device identifier
  20  * @reset_mask: reset mask to use for toggling reset
  21  * @lock: synchronize reset_mask read-modify-writes
  22  */
  23 struct ti_sci_reset_control {
  24         u32 dev_id;
  25         u32 reset_mask;
  26         struct mutex lock;
  27 };
  28
  29 /**
  30  * struct ti_sci_reset_data - reset controller information structure
  31  * @rcdev: reset controller entity
  32  * @dev: reset controller device pointer
  33  * @sci: TI SCI handle used for communication with system controller
  34  * @idr: idr structure for mapping ids to reset control structures
  35  */
  36 struct ti_sci_reset_data {
  37         struct reset_controller_dev rcdev;
  38         struct device *dev;
  39         const struct ti_sci_handle *sci;
  40         struct idr idr;
  41 };
  42
  43 #define to_ti_sci_reset_data(p) \
  44         container_of((p), struct ti_sci_reset_data, rcdev)
  45
  46 /**
  47  * ti_sci_reset_set() - program a device's reset
  48  * @rcdev: reset controller entity
  49  * @id: ID of the reset to toggle
  50  * @assert: boolean flag to indicate assert or deassert
  51  *
  52  * This is a common internal function used to assert or deassert a device's
  53  * reset using the TI SCI protocol. The device's reset is asserted if the
  54  * @assert argument is true, or deasserted if @assert argument is false.
  55  * The mechanism itself is a read-modify-write procedure, the current device
  56  * reset register is read using a TI SCI device operation, the new value is
  57  * set or un-set using the reset's mask, and the new reset value written by
  58  * using another TI SCI device operation.
  59  *
  60  * Return: 0 for successful request, else a corresponding error value
  61  */
  62 static int ti_sci_reset_set(struct reset_controller_dev *rcdev,
  63                             unsigned long id, bool assert)
  64 {
  65         struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
  66         const struct ti_sci_handle *sci = data->sci;
  67         const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops;
  68         struct ti_sci_reset_control *control;
  69         u32 reset_state;
  70         int ret;
  71
  72         control = idr_find(&data->idr, id);
  73         if (!control)
  74                 return -EINVAL;
  75
  76         mutex_lock(&control->lock);
  77
  78         ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state);
  79         if (ret)
  80                 goto out;
  81
  82         if (assert)
  83                 reset_state |= control->reset_mask;
  84         else
  85                 reset_state &= ~control->reset_mask;
  86
  87         ret = dev_ops->set_device_resets(sci, control->dev_id, reset_state);
  88 out:
  89         mutex_unlock(&control->lock);
  90
  91         return ret;
  92 }
  93
  94 /**
  95  * ti_sci_reset_assert() - assert device reset
  96  * @rcdev: reset controller entity
  97  * @id: ID of the reset to be asserted
  98  *
  99  * This function implements the reset driver op to assert a device's reset
 100  * using the TI SCI protocol. This invokes the function ti_sci_reset_set()
 101  * with the corresponding parameters as passed in, but with the @assert
 102  * argument set to true for asserting the reset.
 103  *
 104  * Return: 0 for successful request, else a corresponding error value
 105  */
 106 static int ti_sci_reset_assert(struct reset_controller_dev *rcdev,
 107                                unsigned long id)
 108 {
 109         return ti_sci_reset_set(rcdev, id, true);
 110 }
 111
 112 /**
 113  * ti_sci_reset_deassert() - deassert device reset
 114  * @rcdev: reset controller entity
 115  * @id: ID of the reset to be deasserted
 116  *
 117  * This function implements the reset driver op to deassert a device's reset
 118  * using the TI SCI protocol. This invokes the function ti_sci_reset_set()
 119  * with the corresponding parameters as passed in, but with the @assert
 120  * argument set to false for deasserting the reset.
 121  *
 122  * Return: 0 for successful request, else a corresponding error value
 123  */
 124 static int ti_sci_reset_deassert(struct reset_controller_dev *rcdev,
 125                                  unsigned long id)
 126 {
 127         return ti_sci_reset_set(rcdev, id, false);
 128 }
 129
 130 /**
 131  * ti_sci_reset_status() - check device reset status
 132  * @rcdev: reset controller entity
 133  * @id: ID of reset to be checked
 134  *
 135  * This function implements the reset driver op to return the status of a
 136  * device's reset using the TI SCI protocol. The reset register value is read
 137  * by invoking the TI SCI device operation .get_device_resets(), and the
 138  * status of the specific reset is extracted and returned using this reset's
 139  * reset mask.
 140  *
 141  * Return: 0 if reset is deasserted, or a non-zero value if reset is asserted
 142  */
 143 static int ti_sci_reset_status(struct reset_controller_dev *rcdev,
 144                                unsigned long id)
 145 {
 146         struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
 147         const struct ti_sci_handle *sci = data->sci;
 148         const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops;
 149         struct ti_sci_reset_control *control;
 150         u32 reset_state;
 151         int ret;
 152
 153         control = idr_find(&data->idr, id);
 154         if (!control)
 155                 return -EINVAL;
 156
 157         ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state);
 158         if (ret)
 159                 return ret;
 160
 161         return reset_state & control->reset_mask;
 162 }
 163
 164 static const struct reset_control_ops ti_sci_reset_ops = {
 165         .assert         = ti_sci_reset_assert,
 166         .deassert       = ti_sci_reset_deassert,
 167         .status         = ti_sci_reset_status,
 168 };
 169
 170 /**
 171  * ti_sci_reset_of_xlate() - translate a set of OF arguments to a reset ID
 172  * @rcdev: reset controller entity
 173  * @reset_spec: OF reset argument specifier
 174  *
 175  * This function performs the translation of the reset argument specifier
 176  * values defined in a reset consumer device node. The function allocates a
 177  * reset control structure for that device reset, and will be used by the
 178  * driver for performing any reset functions on that reset. An idr structure
 179  * is allocated and used to map to the reset control structure. This idr
 180  * is used by the driver to do reset lookups.
 181  *
 182  * Return: 0 for successful request, else a corresponding error value
 183  */
 184 static int ti_sci_reset_of_xlate(struct reset_controller_dev *rcdev,
 185                                  const struct of_phandle_args *reset_spec)
 186 {
 187         struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
 188         struct ti_sci_reset_control *control;
 189
 190         if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells))
 191                 return -EINVAL;
 192
 193         control = devm_kzalloc(data->dev, sizeof(*control), GFP_KERNEL);
 194         if (!control)
 195                 return -ENOMEM;
 196
 197         control->dev_id = reset_spec->args[0];
 198         control->reset_mask = reset_spec->args[1];
 199         mutex_init(&control->lock);
 200
 201         return idr_alloc(&data->idr, control, 0, 0, GFP_KERNEL);
 202 }
 203
 204 static const struct of_device_id ti_sci_reset_of_match[] = {
 205         { .compatible = "ti,sci-reset", },
 206         { /* sentinel */ },
 207 };
 208 MODULE_DEVICE_TABLE(of, ti_sci_reset_of_match);
 209
 210 static int ti_sci_reset_probe(struct platform_device *pdev)
 211 {
 212         struct ti_sci_reset_data *data;
 213
 214         if (!pdev->dev.of_node)
 215                 return -ENODEV;
 216
 217         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 218         if (!data)
 219                 return -ENOMEM;
 220
 221         data->sci = devm_ti_sci_get_handle(&pdev->dev);
 222         if (IS_ERR(data->sci))
 223                 return PTR_ERR(data->sci);
 224
 225         data->rcdev.ops = &ti_sci_reset_ops;
 226         data->rcdev.owner = THIS_MODULE;
 227         data->rcdev.of_node = pdev->dev.of_node;
 228         data->rcdev.of_reset_n_cells = 2;
 229         data->rcdev.of_xlate = ti_sci_reset_of_xlate;
 230         data->dev = &pdev->dev;
 231         idr_init(&data->idr);
 232
 233         platform_set_drvdata(pdev, data);
 234
 235         return reset_controller_register(&data->rcdev);
 236 }
 237
 238 static void ti_sci_reset_remove(struct platform_device *pdev)
 239 {
 240         struct ti_sci_reset_data *data = platform_get_drvdata(pdev);
 241
 242         reset_controller_unregister(&data->rcdev);
 243
 244         idr_destroy(&data->idr);
 245 }
 246
 247 static struct platform_driver ti_sci_reset_driver = {
 248         .probe = ti_sci_reset_probe,
 249         .remove_new = ti_sci_reset_remove,
 250         .driver = {
 251                 .name = "ti-sci-reset",
 252                 .of_match_table = ti_sci_reset_of_match,
 253         },
 254 };
 255 module_platform_driver(ti_sci_reset_driver);
 256
 257 MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
 258 MODULE_DESCRIPTION("TI System Control Interface (TI SCI) Reset driver");
 259 MODULE_LICENSE("GPL v2");