drivers/reset/reset-ti-syscon.c

   1 /*
   2  * TI SYSCON regmap reset driver
   3  *
   4  * Copyright (C) 2015-2016 Texas Instruments Incorporated - https://www.ti.com/
   5  *      Andrew F. Davis <afd@ti.com>
   6  *      Suman Anna <afd@ti.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
  13  * kind, whether express or implied; without even the implied warranty
  14  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  */
  17
  18 #include <linux/mfd/syscon.h>
  19 #include <linux/module.h>
  20 #include <linux/of.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/regmap.h>
  23 #include <linux/reset-controller.h>
  24
  25 #include <dt-bindings/reset/ti-syscon.h>
  26
  27 /**
  28  * struct ti_syscon_reset_control - reset control structure
  29  * @assert_offset: reset assert control register offset from syscon base
  30  * @assert_bit: reset assert bit in the reset assert control register
  31  * @deassert_offset: reset deassert control register offset from syscon base
  32  * @deassert_bit: reset deassert bit in the reset deassert control register
  33  * @status_offset: reset status register offset from syscon base
  34  * @status_bit: reset status bit in the reset status register
  35  * @flags: reset flag indicating how the (de)assert and status are handled
  36  */
  37 struct ti_syscon_reset_control {
  38         unsigned int assert_offset;
  39         unsigned int assert_bit;
  40         unsigned int deassert_offset;
  41         unsigned int deassert_bit;
  42         unsigned int status_offset;
  43         unsigned int status_bit;
  44         u32 flags;
  45 };
  46
  47 /**
  48  * struct ti_syscon_reset_data - reset controller information structure
  49  * @rcdev: reset controller entity
  50  * @regmap: regmap handle containing the memory-mapped reset registers
  51  * @controls: array of reset controls
  52  * @nr_controls: number of controls in control array
  53  */
  54 struct ti_syscon_reset_data {
  55         struct reset_controller_dev rcdev;
  56         struct regmap *regmap;
  57         struct ti_syscon_reset_control *controls;
  58         unsigned int nr_controls;
  59 };
  60
  61 #define to_ti_syscon_reset_data(rcdev)  \
  62         container_of(rcdev, struct ti_syscon_reset_data, rcdev)
  63
  64 /**
  65  * ti_syscon_reset_assert() - assert device reset
  66  * @rcdev: reset controller entity
  67  * @id: ID of the reset to be asserted
  68  *
  69  * This function implements the reset driver op to assert a device's reset.
  70  * This asserts the reset in a manner prescribed by the reset flags.
  71  *
  72  * Return: 0 for successful request, else a corresponding error value
  73  */
  74 static int ti_syscon_reset_assert(struct reset_controller_dev *rcdev,
  75                                   unsigned long id)
  76 {
  77         struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
  78         struct ti_syscon_reset_control *control;
  79         unsigned int mask, value;
  80
  81         if (id >= data->nr_controls)
  82                 return -EINVAL;
  83
  84         control = &data->controls[id];
  85
  86         if (control->flags & ASSERT_NONE)
  87                 return -ENOTSUPP; /* assert not supported for this reset */
  88
  89         mask = BIT(control->assert_bit);
  90         value = (control->flags & ASSERT_SET) ? mask : 0x0;
  91
  92         return regmap_write_bits(data->regmap, control->assert_offset, mask, value);
  93 }
  94
  95 /**
  96  * ti_syscon_reset_deassert() - deassert device reset
  97  * @rcdev: reset controller entity
  98  * @id: ID of reset to be deasserted
  99  *
 100  * This function implements the reset driver op to deassert a device's reset.
 101  * This deasserts the reset in a manner prescribed by the reset flags.
 102  *
 103  * Return: 0 for successful request, else a corresponding error value
 104  */
 105 static int ti_syscon_reset_deassert(struct reset_controller_dev *rcdev,
 106                                     unsigned long id)
 107 {
 108         struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
 109         struct ti_syscon_reset_control *control;
 110         unsigned int mask, value;
 111
 112         if (id >= data->nr_controls)
 113                 return -EINVAL;
 114
 115         control = &data->controls[id];
 116
 117         if (control->flags & DEASSERT_NONE)
 118                 return -ENOTSUPP; /* deassert not supported for this reset */
 119
 120         mask = BIT(control->deassert_bit);
 121         value = (control->flags & DEASSERT_SET) ? mask : 0x0;
 122
 123         return regmap_write_bits(data->regmap, control->deassert_offset, mask, value);
 124 }
 125
 126 /**
 127  * ti_syscon_reset_status() - check device reset status
 128  * @rcdev: reset controller entity
 129  * @id: ID of the reset for which the status is being requested
 130  *
 131  * This function implements the reset driver op to return the status of a
 132  * device's reset.
 133  *
 134  * Return: 0 if reset is deasserted, true if reset is asserted, else a
 135  * corresponding error value
 136  */
 137 static int ti_syscon_reset_status(struct reset_controller_dev *rcdev,
 138                                   unsigned long id)
 139 {
 140         struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
 141         struct ti_syscon_reset_control *control;
 142         unsigned int reset_state;
 143         int ret;
 144
 145         if (id >= data->nr_controls)
 146                 return -EINVAL;
 147
 148         control = &data->controls[id];
 149
 150         if (control->flags & STATUS_NONE)
 151                 return -ENOTSUPP; /* status not supported for this reset */
 152
 153         ret = regmap_read(data->regmap, control->status_offset, &reset_state);
 154         if (ret)
 155                 return ret;
 156
 157         return !(reset_state & BIT(control->status_bit)) ==
 158                 !(control->flags & STATUS_SET);
 159 }
 160
 161 static const struct reset_control_ops ti_syscon_reset_ops = {
 162         .assert         = ti_syscon_reset_assert,
 163         .deassert       = ti_syscon_reset_deassert,
 164         .status         = ti_syscon_reset_status,
 165 };
 166
 167 static int ti_syscon_reset_probe(struct platform_device *pdev)
 168 {
 169         struct device *dev = &pdev->dev;
 170         struct device_node *np = dev->of_node;
 171         struct ti_syscon_reset_data *data;
 172         struct regmap *regmap;
 173         const __be32 *list;
 174         struct ti_syscon_reset_control *controls;
 175         int size, nr_controls, i;
 176
 177         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 178         if (!data)
 179                 return -ENOMEM;
 180
 181         regmap = syscon_node_to_regmap(np->parent);
 182         if (IS_ERR(regmap))
 183                 return PTR_ERR(regmap);
 184
 185         list = of_get_property(np, "ti,reset-bits", &size);
 186         if (!list || (size / sizeof(*list)) % 7 != 0) {
 187                 dev_err(dev, "invalid DT reset description\n");
 188                 return -EINVAL;
 189         }
 190
 191         nr_controls = (size / sizeof(*list)) / 7;
 192         controls = devm_kcalloc(dev, nr_controls, sizeof(*controls),
 193                                 GFP_KERNEL);
 194         if (!controls)
 195                 return -ENOMEM;
 196
 197         for (i = 0; i < nr_controls; i++) {
 198                 controls[i].assert_offset = be32_to_cpup(list++);
 199                 controls[i].assert_bit = be32_to_cpup(list++);
 200                 controls[i].deassert_offset = be32_to_cpup(list++);
 201                 controls[i].deassert_bit = be32_to_cpup(list++);
 202                 controls[i].status_offset = be32_to_cpup(list++);
 203                 controls[i].status_bit = be32_to_cpup(list++);
 204                 controls[i].flags = be32_to_cpup(list++);
 205         }
 206
 207         data->rcdev.ops = &ti_syscon_reset_ops;
 208         data->rcdev.owner = THIS_MODULE;
 209         data->rcdev.of_node = np;
 210         data->rcdev.nr_resets = nr_controls;
 211         data->regmap = regmap;
 212         data->controls = controls;
 213         data->nr_controls = nr_controls;
 214
 215         platform_set_drvdata(pdev, data);
 216
 217         return devm_reset_controller_register(dev, &data->rcdev);
 218 }
 219
 220 static const struct of_device_id ti_syscon_reset_of_match[] = {
 221         { .compatible = "ti,syscon-reset", },
 222         { /* sentinel */ },
 223 };
 224 MODULE_DEVICE_TABLE(of, ti_syscon_reset_of_match);
 225
 226 static struct platform_driver ti_syscon_reset_driver = {
 227         .probe = ti_syscon_reset_probe,
 228         .driver = {
 229                 .name = "ti-syscon-reset",
 230                 .of_match_table = ti_syscon_reset_of_match,
 231         },
 232 };
 233 module_platform_driver(ti_syscon_reset_driver);
 234
 235 MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
 236 MODULE_AUTHOR("Suman Anna <s-anna@ti.com>");
 237 MODULE_DESCRIPTION("TI SYSCON Regmap Reset Driver");
 238 MODULE_LICENSE("GPL v2");