drivers/reset/reset-ti-sci.c

   1 /*
   2  * Texas Instrument's System Control Interface (TI-SCI) reset driver
   3  *
   4  * Copyright (C) 2015-2017 Texas Instruments Incorporated - http://www.ti.com/
   5  *      Andrew F. Davis <afd@ti.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
  12  * kind, whether express or implied; without even the implied warranty
  13  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  */
  16
  17 #include <linux/idr.h>
  18 #include <linux/module.h>
  19 #include <linux/mutex.h>
  20 #include <linux/of.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/reset-controller.h>
  23 #include <linux/soc/ti/ti_sci_protocol.h>
  24
  25 /**
  26  * struct ti_sci_reset_control - reset control structure
  27  * @dev_id: SoC-specific device identifier
  28  * @reset_mask: reset mask to use for toggling reset
  29  * @lock: synchronize reset_mask read-modify-writes
  30  */
  31 struct ti_sci_reset_control {
  32         u32 dev_id;
  33         u32 reset_mask;
  34         struct mutex lock;
  35 };
  36
  37 /**
  38  * struct ti_sci_reset_data - reset controller information structure
  39  * @rcdev: reset controller entity
  40  * @dev: reset controller device pointer
  41  * @sci: TI SCI handle used for communication with system controller
  42  * @idr: idr structure for mapping ids to reset control structures
  43  */
  44 struct ti_sci_reset_data {
  45         struct reset_controller_dev rcdev;
  46         struct device *dev;
  47         const struct ti_sci_handle *sci;
  48         struct idr idr;
  49 };
  50
  51 #define to_ti_sci_reset_data(p) \
  52         container_of((p), struct ti_sci_reset_data, rcdev)
  53
  54 /**
  55  * ti_sci_reset_set() - program a device's reset
  56  * @rcdev: reset controller entity
  57  * @id: ID of the reset to toggle
  58  * @assert: boolean flag to indicate assert or deassert
  59  *
  60  * This is a common internal function used to assert or deassert a device's
  61  * reset using the TI SCI protocol. The device's reset is asserted if the
  62  * @assert argument is true, or deasserted if @assert argument is false.
  63  * The mechanism itself is a read-modify-write procedure, the current device
  64  * reset register is read using a TI SCI device operation, the new value is
  65  * set or un-set using the reset's mask, and the new reset value written by
  66  * using another TI SCI device operation.
  67  *
  68  * Return: 0 for successful request, else a corresponding error value
  69  */
  70 static int ti_sci_reset_set(struct reset_controller_dev *rcdev,
  71                             unsigned long id, bool assert)
  72 {
  73         struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
  74         const struct ti_sci_handle *sci = data->sci;
  75         const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops;
  76         struct ti_sci_reset_control *control;
  77         u32 reset_state;
  78         int ret;
  79
  80         control = idr_find(&data->idr, id);
  81         if (!control)
  82                 return -EINVAL;
  83
  84         mutex_lock(&control->lock);
  85
  86         ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state);
  87         if (ret)
  88                 goto out;
  89
  90         if (assert)
  91                 reset_state |= control->reset_mask;
  92         else
  93                 reset_state &= ~control->reset_mask;
  94
  95         ret = dev_ops->set_device_resets(sci, control->dev_id, reset_state);
  96 out:
  97         mutex_unlock(&control->lock);
  98
  99         return ret;
 100 }
 101
 102 /**
 103  * ti_sci_reset_assert() - assert device reset
 104  * @rcdev: reset controller entity
 105  * @id: ID of the reset to be asserted
 106  *
 107  * This function implements the reset driver op to assert a device's reset
 108  * using the TI SCI protocol. This invokes the function ti_sci_reset_set()
 109  * with the corresponding parameters as passed in, but with the @assert
 110  * argument set to true for asserting the reset.
 111  *
 112  * Return: 0 for successful request, else a corresponding error value
 113  */
 114 static int ti_sci_reset_assert(struct reset_controller_dev *rcdev,
 115                                unsigned long id)
 116 {
 117         return ti_sci_reset_set(rcdev, id, true);
 118 }
 119
 120 /**
 121  * ti_sci_reset_deassert() - deassert device reset
 122  * @rcdev: reset controller entity
 123  * @id: ID of the reset to be deasserted
 124  *
 125  * This function implements the reset driver op to deassert a device's reset
 126  * using the TI SCI protocol. This invokes the function ti_sci_reset_set()
 127  * with the corresponding parameters as passed in, but with the @assert
 128  * argument set to false for deasserting the reset.
 129  *
 130  * Return: 0 for successful request, else a corresponding error value
 131  */
 132 static int ti_sci_reset_deassert(struct reset_controller_dev *rcdev,
 133                                  unsigned long id)
 134 {
 135         return ti_sci_reset_set(rcdev, id, false);
 136 }
 137
 138 /**
 139  * ti_sci_reset_status() - check device reset status
 140  * @rcdev: reset controller entity
 141  * @id: ID of reset to be checked
 142  *
 143  * This function implements the reset driver op to return the status of a
 144  * device's reset using the TI SCI protocol. The reset register value is read
 145  * by invoking the TI SCI device operation .get_device_resets(), and the
 146  * status of the specific reset is extracted and returned using this reset's
 147  * reset mask.
 148  *
 149  * Return: 0 if reset is deasserted, or a non-zero value if reset is asserted
 150  */
 151 static int ti_sci_reset_status(struct reset_controller_dev *rcdev,
 152                                unsigned long id)
 153 {
 154         struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
 155         const struct ti_sci_handle *sci = data->sci;
 156         const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops;
 157         struct ti_sci_reset_control *control;
 158         u32 reset_state;
 159         int ret;
 160
 161         control = idr_find(&data->idr, id);
 162         if (!control)
 163                 return -EINVAL;
 164
 165         ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state);
 166         if (ret)
 167                 return ret;
 168
 169         return reset_state & control->reset_mask;
 170 }
 171
 172 static const struct reset_control_ops ti_sci_reset_ops = {
 173         .assert         = ti_sci_reset_assert,
 174         .deassert       = ti_sci_reset_deassert,
 175         .status         = ti_sci_reset_status,
 176 };
 177
 178 /**
 179  * ti_sci_reset_of_xlate() - translate a set of OF arguments to a reset ID
 180  * @rcdev: reset controller entity
 181  * @reset_spec: OF reset argument specifier
 182  *
 183  * This function performs the translation of the reset argument specifier
 184  * values defined in a reset consumer device node. The function allocates a
 185  * reset control structure for that device reset, and will be used by the
 186  * driver for performing any reset functions on that reset. An idr structure
 187  * is allocated and used to map to the reset control structure. This idr
 188  * is used by the driver to do reset lookups.
 189  *
 190  * Return: 0 for successful request, else a corresponding error value
 191  */
 192 static int ti_sci_reset_of_xlate(struct reset_controller_dev *rcdev,
 193                                  const struct of_phandle_args *reset_spec)
 194 {
 195         struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
 196         struct ti_sci_reset_control *control;
 197
 198         if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells))
 199                 return -EINVAL;
 200
 201         control = devm_kzalloc(data->dev, sizeof(*control), GFP_KERNEL);
 202         if (!control)
 203                 return -ENOMEM;
 204
 205         control->dev_id = reset_spec->args[0];
 206         control->reset_mask = reset_spec->args[1];
 207         mutex_init(&control->lock);
 208
 209         return idr_alloc(&data->idr, control, 0, 0, GFP_KERNEL);
 210 }
 211
 212 static const struct of_device_id ti_sci_reset_of_match[] = {
 213         { .compatible = "ti,sci-reset", },
 214         { /* sentinel */ },
 215 };
 216 MODULE_DEVICE_TABLE(of, ti_sci_reset_of_match);
 217
 218 static int ti_sci_reset_probe(struct platform_device *pdev)
 219 {
 220         struct ti_sci_reset_data *data;
 221
 222         if (!pdev->dev.of_node)
 223                 return -ENODEV;
 224
 225         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 226         if (!data)
 227                 return -ENOMEM;
 228
 229         data->sci = devm_ti_sci_get_handle(&pdev->dev);
 230         if (IS_ERR(data->sci))
 231                 return PTR_ERR(data->sci);
 232
 233         data->rcdev.ops = &ti_sci_reset_ops;
 234         data->rcdev.owner = THIS_MODULE;
 235         data->rcdev.of_node = pdev->dev.of_node;
 236         data->rcdev.of_reset_n_cells = 2;
 237         data->rcdev.of_xlate = ti_sci_reset_of_xlate;
 238         data->dev = &pdev->dev;
 239         idr_init(&data->idr);
 240
 241         platform_set_drvdata(pdev, data);
 242
 243         return reset_controller_register(&data->rcdev);
 244 }
 245
 246 static int ti_sci_reset_remove(struct platform_device *pdev)
 247 {
 248         struct ti_sci_reset_data *data = platform_get_drvdata(pdev);
 249
 250         reset_controller_unregister(&data->rcdev);
 251
 252         idr_destroy(&data->idr);
 253
 254         return 0;
 255 }
 256
 257 static struct platform_driver ti_sci_reset_driver = {
 258         .probe = ti_sci_reset_probe,
 259         .remove = ti_sci_reset_remove,
 260         .driver = {
 261                 .name = "ti-sci-reset",
 262                 .of_match_table = ti_sci_reset_of_match,
 263         },
 264 };
 265 module_platform_driver(ti_sci_reset_driver);
 266
 267 MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
 268 MODULE_DESCRIPTION("TI System Control Interface (TI SCI) Reset driver");
 269 MODULE_LICENSE("GPL v2");