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 } 207