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  * struct syscfg_reset_channel - 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  * struct syscfg_reset_controller - A reset controller which groups together
  32  * a set of related reset bits, which may be located in different system
  33  * configuration registers.
  34  *
  35  * @rst: base reset controller structure.
  36  * @active_low: are the resets in this controller active low, i.e. clearing
  37  *              the reset bit puts the hardware into reset.
  38  * @channels: An array of reset channels for this controller.
  39  */
  40 struct syscfg_reset_controller {
  41         struct reset_controller_dev rst;
  42         bool active_low;
  43         struct syscfg_reset_channel *channels;
  44 };
  45
  46 #define to_syscfg_reset_controller(_rst) \
  47         container_of(_rst, struct syscfg_reset_controller, rst)
  48
  49 static int syscfg_reset_program_hw(struct reset_controller_dev *rcdev,
  50                                    unsigned long idx, int assert)
  51 {
  52         struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
  53         const struct syscfg_reset_channel *ch;
  54         u32 ctrl_val = rst->active_low ? !assert : !!assert;
  55         int err;
  56
  57         if (idx >= rcdev->nr_resets)
  58                 return -EINVAL;
  59
  60         ch = &rst->channels[idx];
  61
  62         err = regmap_field_write(ch->reset, ctrl_val);
  63         if (err)
  64                 return err;
  65
  66         if (ch->ack) {
  67                 unsigned long timeout = jiffies + msecs_to_jiffies(1000);
  68                 u32 ack_val;
  69
  70                 while (true) {
  71                         err = regmap_field_read(ch->ack, &ack_val);
  72                         if (err)
  73                                 return err;
  74
  75                         if (ack_val == ctrl_val)
  76                                 break;
  77
  78                         if (time_after(jiffies, timeout))
  79                                 return -ETIME;
  80
  81                         cpu_relax();
  82                 }
  83         }
  84
  85         return 0;
  86 }
  87
  88 static int syscfg_reset_assert(struct reset_controller_dev *rcdev,
  89                                unsigned long idx)
  90 {
  91         return syscfg_reset_program_hw(rcdev, idx, true);
  92 }
  93
  94 static int syscfg_reset_deassert(struct reset_controller_dev *rcdev,
  95                                  unsigned long idx)
  96 {
  97         return syscfg_reset_program_hw(rcdev, idx, false);
  98 }
  99
 100 static int syscfg_reset_dev(struct reset_controller_dev *rcdev,
 101                             unsigned long idx)
 102 {
 103         int err;
 104
 105         err = syscfg_reset_assert(rcdev, idx);
 106         if (err)
 107                 return err;
 108
 109         return syscfg_reset_deassert(rcdev, idx);
 110 }
 111
 112 static int syscfg_reset_status(struct reset_controller_dev *rcdev,
 113                                unsigned long idx)
 114 {
 115         struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
 116         const struct syscfg_reset_channel *ch;
 117         u32 ret_val = 0;
 118         int err;
 119
 120         if (idx >= rcdev->nr_resets)
 121                 return -EINVAL;
 122
 123         ch = &rst->channels[idx];
 124         if (ch->ack)
 125                 err = regmap_field_read(ch->ack, &ret_val);
 126         else
 127                 err = regmap_field_read(ch->reset, &ret_val);
 128         if (err)
 129                 return err;
 130
 131         return rst->active_low ? !ret_val : !!ret_val;
 132 }
 133
 134 static const struct reset_control_ops syscfg_reset_ops = {
 135         .reset    = syscfg_reset_dev,
 136         .assert   = syscfg_reset_assert,
 137         .deassert = syscfg_reset_deassert,
 138         .status   = syscfg_reset_status,
 139 };
 140
 141 static int syscfg_reset_controller_register(struct device *dev,
 142                                 const struct syscfg_reset_controller_data *data)
 143 {
 144         struct syscfg_reset_controller *rc;
 145         int i, err;
 146
 147         rc = devm_kzalloc(dev, sizeof(*rc), GFP_KERNEL);
 148         if (!rc)
 149                 return -ENOMEM;
 150
 151         rc->channels = devm_kcalloc(dev, data->nr_channels,
 152                                     sizeof(*rc->channels), GFP_KERNEL);
 153         if (!rc->channels)
 154                 return -ENOMEM;
 155
 156         rc->rst.ops = &syscfg_reset_ops,
 157         rc->rst.of_node = dev->of_node;
 158         rc->rst.nr_resets = data->nr_channels;
 159         rc->active_low = data->active_low;
 160
 161         for (i = 0; i < data->nr_channels; i++) {
 162                 struct regmap *map;
 163                 struct regmap_field *f;
 164                 const char *compatible = data->channels[i].compatible;
 165
 166                 map = syscon_regmap_lookup_by_compatible(compatible);
 167                 if (IS_ERR(map))
 168                         return PTR_ERR(map);
 169
 170                 f = devm_regmap_field_alloc(dev, map, data->channels[i].reset);
 171                 if (IS_ERR(f))
 172                         return PTR_ERR(f);
 173
 174                 rc->channels[i].reset = f;
 175
 176                 if (!data->wait_for_ack)
 177                         continue;
 178
 179                 f = devm_regmap_field_alloc(dev, map, data->channels[i].ack);
 180                 if (IS_ERR(f))
 181                         return PTR_ERR(f);
 182
 183                 rc->channels[i].ack = f;
 184         }
 185
 186         err = reset_controller_register(&rc->rst);
 187         if (!err)
 188                 dev_info(dev, "registered\n");
 189
 190         return err;
 191 }
 192
 193 int syscfg_reset_probe(struct platform_device *pdev)
 194 {
 195         struct device *dev = pdev ? &pdev->dev : NULL;
 196         const struct of_device_id *match;
 197
 198         if (!dev || !dev->driver)
 199                 return -ENODEV;
 200
 201         match = of_match_device(dev->driver->of_match_table, dev);
 202         if (!match || !match->data)
 203                 return -EINVAL;
 204
 205         return syscfg_reset_controller_register(dev, match->data);
 206 }