drivers/reset/sti/reset-syscfg.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2013 STMicroelectronics Limited
   4  * Author: Stephen Gallimore <stephen.gallimore@st.com>
   5  *
   6  * Inspired by mach-imx/src.c
   7  */
   8 #include <linux/kernel.h>
   9 #include <linux/platform_device.h>
  10 #include <linux/module.h>
  11 #include <linux/err.h>
  12 #include <linux/types.h>
  13 #include <linux/of_device.h>
  14 #include <linux/regmap.h>
  15 #include <linux/mfd/syscon.h>
  16
  17 #include "reset-syscfg.h"
  18
  19 /**
  20  * Reset channel regmap configuration
  21  *
  22  * @reset: regmap field for the channel's reset bit.
  23  * @ack: regmap field for the channel's ack bit (optional).
  24  */
  25 struct syscfg_reset_channel {
  26         struct regmap_field *reset;
  27         struct regmap_field *ack;
  28 };
  29
  30 /**
  31  * A reset controller which groups together a set of related reset bits, which
  32  * may be located in different system configuration registers.
  33  *
  34  * @rst: base reset controller structure.
  35  * @active_low: are the resets in this controller active low, i.e. clearing
  36  *              the reset bit puts the hardware into reset.
  37  * @channels: An array of reset channels for this controller.
  38  */
  39 struct syscfg_reset_controller {
  40         struct reset_controller_dev rst;
  41         bool active_low;
  42         struct syscfg_reset_channel *channels;
  43 };
  44
  45 #define to_syscfg_reset_controller(_rst) \
  46         container_of(_rst, struct syscfg_reset_controller, rst)
  47
  48 static int syscfg_reset_program_hw(struct reset_controller_dev *rcdev,
  49                                    unsigned long idx, int assert)
  50 {
  51         struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
  52         const struct syscfg_reset_channel *ch;
  53         u32 ctrl_val = rst->active_low ? !assert : !!assert;
  54         int err;
  55
  56         if (idx >= rcdev->nr_resets)
  57                 return -EINVAL;
  58
  59         ch = &rst->channels[idx];
  60
  61         err = regmap_field_write(ch->reset, ctrl_val);
  62         if (err)
  63                 return err;
  64
  65         if (ch->ack) {
  66                 unsigned long timeout = jiffies + msecs_to_jiffies(1000);
  67                 u32 ack_val;
  68
  69                 while (true) {
  70                         err = regmap_field_read(ch->ack, &ack_val);
  71                         if (err)
  72                                 return err;
  73
  74                         if (ack_val == ctrl_val)
  75                                 break;
  76
  77                         if (time_after(jiffies, timeout))
  78                                 return -ETIME;
  79
  80                         cpu_relax();
  81                 }
  82         }
  83
  84         return 0;
  85 }
  86
  87 static int syscfg_reset_assert(struct reset_controller_dev *rcdev,
  88                                unsigned long idx)
  89 {
  90         return syscfg_reset_program_hw(rcdev, idx, true);
  91 }
  92
  93 static int syscfg_reset_deassert(struct reset_controller_dev *rcdev,
  94                                  unsigned long idx)
  95 {
  96         return syscfg_reset_program_hw(rcdev, idx, false);
  97 }
  98
  99 static int syscfg_reset_dev(struct reset_controller_dev *rcdev,
 100                             unsigned long idx)
 101 {
 102         int err;
 103
 104         err = syscfg_reset_assert(rcdev, idx);
 105         if (err)
 106                 return err;
 107
 108         return syscfg_reset_deassert(rcdev, idx);
 109 }
 110
 111 static int syscfg_reset_status(struct reset_controller_dev *rcdev,
 112                                unsigned long idx)
 113 {
 114         struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
 115         const struct syscfg_reset_channel *ch;
 116         u32 ret_val = 0;
 117         int err;
 118
 119         if (idx >= rcdev->nr_resets)
 120                 return -EINVAL;
 121
 122         ch = &rst->channels[idx];
 123         if (ch->ack)
 124                 err = regmap_field_read(ch->ack, &ret_val);
 125         else
 126                 err = regmap_field_read(ch->reset, &ret_val);
 127         if (err)
 128                 return err;
 129
 130         return rst->active_low ? !ret_val : !!ret_val;
 131 }
 132
 133 static const struct reset_control_ops syscfg_reset_ops = {
 134         .reset    = syscfg_reset_dev,
 135         .assert   = syscfg_reset_assert,
 136         .deassert = syscfg_reset_deassert,
 137         .status   = syscfg_reset_status,
 138 };
 139
 140 static int syscfg_reset_controller_register(struct device *dev,
 141                                 const struct syscfg_reset_controller_data *data)
 142 {
 143         struct syscfg_reset_controller *rc;
 144         int i, err;
 145
 146         rc = devm_kzalloc(dev, sizeof(*rc), GFP_KERNEL);
 147         if (!rc)
 148                 return -ENOMEM;
 149
 150         rc->channels = devm_kcalloc(dev, data->nr_channels,
 151                                     sizeof(*rc->channels), GFP_KERNEL);
 152         if (!rc->channels)
 153                 return -ENOMEM;
 154
 155         rc->rst.ops = &syscfg_reset_ops,
 156         rc->rst.of_node = dev->of_node;
 157         rc->rst.nr_resets = data->nr_channels;
 158         rc->active_low = data->active_low;
 159
 160         for (i = 0; i < data->nr_channels; i++) {
 161                 struct regmap *map;
 162                 struct regmap_field *f;
 163                 const char *compatible = data->channels[i].compatible;
 164
 165                 map = syscon_regmap_lookup_by_compatible(compatible);
 166                 if (IS_ERR(map))
 167                         return PTR_ERR(map);
 168
 169                 f = devm_regmap_field_alloc(dev, map, data->channels[i].reset);
 170                 if (IS_ERR(f))
 171                         return PTR_ERR(f);
 172
 173                 rc->channels[i].reset = f;
 174
 175                 if (!data->wait_for_ack)
 176                         continue;
 177
 178                 f = devm_regmap_field_alloc(dev, map, data->channels[i].ack);
 179                 if (IS_ERR(f))
 180                         return PTR_ERR(f);
 181
 182                 rc->channels[i].ack = f;
 183         }
 184
 185         err = reset_controller_register(&rc->rst);
 186         if (!err)
 187                 dev_info(dev, "registered\n");
 188
 189         return err;
 190 }
 191
 192 int syscfg_reset_probe(struct platform_device *pdev)
 193 {
 194         struct device *dev = pdev ? &pdev->dev : NULL;
 195         const struct of_device_id *match;
 196
 197         if (!dev || !dev->driver)
 198                 return -ENODEV;
 199
 200         match = of_match_device(dev->driver->of_match_table, dev);
 201         if (!match || !match->data)
 202                 return -EINVAL;
 203
 204         return syscfg_reset_controller_register(dev, match->data);
 205 }