drivers/reset/reset-ti-syscon.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * TI SYSCON regmap reset driver
   4  *
   5  * Copyright (C) 2015-2016 Texas Instruments Incorporated - https://www.ti.com/
   6  *      Andrew F. Davis <afd@ti.com>
   7  *      Suman Anna <afd@ti.com>
   8  */
   9
  10 #include <linux/mfd/syscon.h>
  11 #include <linux/module.h>
  12 #include <linux/of.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/regmap.h>
  15 #include <linux/reset-controller.h>
  16
  17 #include <dt-bindings/reset/ti-syscon.h>
  18
  19 /**
  20  * struct ti_syscon_reset_control - reset control structure
  21  * @assert_offset: reset assert control register offset from syscon base
  22  * @assert_bit: reset assert bit in the reset assert control register
  23  * @deassert_offset: reset deassert control register offset from syscon base
  24  * @deassert_bit: reset deassert bit in the reset deassert control register
  25  * @status_offset: reset status register offset from syscon base
  26  * @status_bit: reset status bit in the reset status register
  27  * @flags: reset flag indicating how the (de)assert and status are handled
  28  */
  29 struct ti_syscon_reset_control {
  30         unsigned int assert_offset;
  31         unsigned int assert_bit;
  32         unsigned int deassert_offset;
  33         unsigned int deassert_bit;
  34         unsigned int status_offset;
  35         unsigned int status_bit;
  36         u32 flags;
  37 };
  38
  39 /**
  40  * struct ti_syscon_reset_data - reset controller information structure
  41  * @rcdev: reset controller entity
  42  * @regmap: regmap handle containing the memory-mapped reset registers
  43  * @controls: array of reset controls
  44  * @nr_controls: number of controls in control array
  45  */
  46 struct ti_syscon_reset_data {
  47         struct reset_controller_dev rcdev;
  48         struct regmap *regmap;
  49         struct ti_syscon_reset_control *controls;
  50         unsigned int nr_controls;
  51 };
  52
  53 #define to_ti_syscon_reset_data(_rcdev) \
  54         container_of(_rcdev, struct ti_syscon_reset_data, rcdev)
  55
  56 /**
  57  * ti_syscon_reset_assert() - assert device reset
  58  * @rcdev: reset controller entity
  59  * @id: ID of the reset to be asserted
  60  *
  61  * This function implements the reset driver op to assert a device's reset.
  62  * This asserts the reset in a manner prescribed by the reset flags.
  63  *
  64  * Return: 0 for successful request, else a corresponding error value
  65  */
  66 static int ti_syscon_reset_assert(struct reset_controller_dev *rcdev,
  67                                   unsigned long id)
  68 {
  69         struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
  70         struct ti_syscon_reset_control *control;
  71         unsigned int mask, value;
  72
  73         if (id >= data->nr_controls)
  74                 return -EINVAL;
  75
  76         control = &data->controls[id];
  77
  78         if (control->flags & ASSERT_NONE)
  79                 return -ENOTSUPP; /* assert not supported for this reset */
  80
  81         mask = BIT(control->assert_bit);
  82         value = (control->flags & ASSERT_SET) ? mask : 0x0;
  83
  84         return regmap_write_bits(data->regmap, control->assert_offset, mask, value);
  85 }
  86
  87 /**
  88  * ti_syscon_reset_deassert() - deassert device reset
  89  * @rcdev: reset controller entity
  90  * @id: ID of reset to be deasserted
  91  *
  92  * This function implements the reset driver op to deassert a device's reset.
  93  * This deasserts the reset in a manner prescribed by the reset flags.
  94  *
  95  * Return: 0 for successful request, else a corresponding error value
  96  */
  97 static int ti_syscon_reset_deassert(struct reset_controller_dev *rcdev,
  98                                     unsigned long id)
  99 {
 100         struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
 101         struct ti_syscon_reset_control *control;
 102         unsigned int mask, value;
 103
 104         if (id >= data->nr_controls)
 105                 return -EINVAL;
 106
 107         control = &data->controls[id];
 108
 109         if (control->flags & DEASSERT_NONE)
 110                 return -ENOTSUPP; /* deassert not supported for this reset */
 111
 112         mask = BIT(control->deassert_bit);
 113         value = (control->flags & DEASSERT_SET) ? mask : 0x0;
 114
 115         return regmap_write_bits(data->regmap, control->deassert_offset, mask, value);
 116 }
 117
 118 /**
 119  * ti_syscon_reset_status() - check device reset status
 120  * @rcdev: reset controller entity
 121  * @id: ID of the reset for which the status is being requested
 122  *
 123  * This function implements the reset driver op to return the status of a
 124  * device's reset.
 125  *
 126  * Return: 0 if reset is deasserted, true if reset is asserted, else a
 127  * corresponding error value
 128  */
 129 static int ti_syscon_reset_status(struct reset_controller_dev *rcdev,
 130                                   unsigned long id)
 131 {
 132         struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
 133         struct ti_syscon_reset_control *control;
 134         unsigned int reset_state;
 135         int ret;
 136
 137         if (id >= data->nr_controls)
 138                 return -EINVAL;
 139
 140         control = &data->controls[id];
 141
 142         if (control->flags & STATUS_NONE)
 143                 return -ENOTSUPP; /* status not supported for this reset */
 144
 145         ret = regmap_read(data->regmap, control->status_offset, &reset_state);
 146         if (ret)
 147                 return ret;
 148
 149         return !(reset_state & BIT(control->status_bit)) ==
 150                 !(control->flags & STATUS_SET);
 151 }
 152
 153 static const struct reset_control_ops ti_syscon_reset_ops = {
 154         .assert         = ti_syscon_reset_assert,
 155         .deassert       = ti_syscon_reset_deassert,
 156         .status         = ti_syscon_reset_status,
 157 };
 158
 159 static int ti_syscon_reset_probe(struct platform_device *pdev)
 160 {
 161         struct device *dev = &pdev->dev;
 162         struct device_node *np = dev->of_node;
 163         struct ti_syscon_reset_data *data;
 164         struct regmap *regmap;
 165         const __be32 *list;
 166         struct ti_syscon_reset_control *controls;
 167         int size, nr_controls, i;
 168
 169         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 170         if (!data)
 171                 return -ENOMEM;
 172
 173         regmap = syscon_node_to_regmap(np->parent);
 174         if (IS_ERR(regmap))
 175                 return PTR_ERR(regmap);
 176
 177         list = of_get_property(np, "ti,reset-bits", &size);
 178         if (!list || (size / sizeof(*list)) % 7 != 0) {
 179                 dev_err(dev, "invalid DT reset description\n");
 180                 return -EINVAL;
 181         }
 182
 183         nr_controls = (size / sizeof(*list)) / 7;
 184         controls = devm_kcalloc(dev, nr_controls, sizeof(*controls),
 185                                 GFP_KERNEL);
 186         if (!controls)
 187                 return -ENOMEM;
 188
 189         for (i = 0; i < nr_controls; i++) {
 190                 controls[i].assert_offset = be32_to_cpup(list++);
 191                 controls[i].assert_bit = be32_to_cpup(list++);
 192                 controls[i].deassert_offset = be32_to_cpup(list++);
 193                 controls[i].deassert_bit = be32_to_cpup(list++);
 194                 controls[i].status_offset = be32_to_cpup(list++);
 195                 controls[i].status_bit = be32_to_cpup(list++);
 196                 controls[i].flags = be32_to_cpup(list++);
 197         }
 198
 199         data->rcdev.ops = &ti_syscon_reset_ops;
 200         data->rcdev.owner = THIS_MODULE;
 201         data->rcdev.of_node = np;
 202         data->rcdev.nr_resets = nr_controls;
 203         data->regmap = regmap;
 204         data->controls = controls;
 205         data->nr_controls = nr_controls;
 206
 207         return devm_reset_controller_register(dev, &data->rcdev);
 208 }
 209
 210 static const struct of_device_id ti_syscon_reset_of_match[] = {
 211         { .compatible = "ti,syscon-reset", },
 212         { /* sentinel */ },
 213 };
 214 MODULE_DEVICE_TABLE(of, ti_syscon_reset_of_match);
 215
 216 static struct platform_driver ti_syscon_reset_driver = {
 217         .probe = ti_syscon_reset_probe,
 218         .driver = {
 219                 .name = "ti-syscon-reset",
 220                 .of_match_table = ti_syscon_reset_of_match,
 221         },
 222 };
 223 module_platform_driver(ti_syscon_reset_driver);
 224
 225 MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
 226 MODULE_AUTHOR("Suman Anna <s-anna@ti.com>");
 227 MODULE_DESCRIPTION("TI SYSCON Regmap Reset Driver");
 228 MODULE_LICENSE("GPL v2");