1 /* 2 * Texas Instrument's System Control Interface (TI-SCI) reset driver 3 * 4 * Copyright (C) 2015-2017 Texas Instruments Incorporated - http://www.ti.com/ 5 * Andrew F. Davis <afd@ti.com> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 * 11 * This program is distributed "as is" WITHOUT ANY WARRANTY of any 12 * kind, whether express or implied; without even the implied warranty 13 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 */ 16 17 #include <linux/idr.h> 18 #include <linux/module.h> 19 #include <linux/mutex.h> 20 #include <linux/of.h> 21 #include <linux/platform_device.h> 22 #include <linux/reset-controller.h> 23 #include <linux/soc/ti/ti_sci_protocol.h> 24 25 /** 26 * struct ti_sci_reset_control - reset control structure 27 * @dev_id: SoC-specific device identifier 28 * @reset_mask: reset mask to use for toggling reset 29 * @lock: synchronize reset_mask read-modify-writes 30 */ 31 struct ti_sci_reset_control { 32 u32 dev_id; 33 u32 reset_mask; 34 struct mutex lock; 35 }; 36 37 /** 38 * struct ti_sci_reset_data - reset controller information structure 39 * @rcdev: reset controller entity 40 * @dev: reset controller device pointer 41 * @sci: TI SCI handle used for communication with system controller 42 * @idr: idr structure for mapping ids to reset control structures 43 */ 44 struct ti_sci_reset_data { 45 struct reset_controller_dev rcdev; 46 struct device *dev; 47 const struct ti_sci_handle *sci; 48 struct idr idr; 49 }; 50 51 #define to_ti_sci_reset_data(p) \ 52 container_of((p), struct ti_sci_reset_data, rcdev) 53 54 /** 55 * ti_sci_reset_set() - program a device's reset 56 * @rcdev: reset controller entity 57 * @id: ID of the reset to toggle 58 * @assert: boolean flag to indicate assert or deassert 59 * 60 * This is a common internal function used to assert or deassert a device's 61 * reset using the TI SCI protocol. The device's reset is asserted if the 62 * @assert argument is true, or deasserted if @assert argument is false. 63 * The mechanism itself is a read-modify-write procedure, the current device 64 * reset register is read using a TI SCI device operation, the new value is 65 * set or un-set using the reset's mask, and the new reset value written by 66 * using another TI SCI device operation. 67 * 68 * Return: 0 for successful request, else a corresponding error value 69 */ 70 static int ti_sci_reset_set(struct reset_controller_dev *rcdev, 71 unsigned long id, bool assert) 72 { 73 struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev); 74 const struct ti_sci_handle *sci = data->sci; 75 const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops; 76 struct ti_sci_reset_control *control; 77 u32 reset_state; 78 int ret; 79 80 control = idr_find(&data->idr, id); 81 if (!control) 82 return -EINVAL; 83 84 mutex_lock(&control->lock); 85 86 ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state); 87 if (ret) 88 goto out; 89 90 if (assert) 91 reset_state |= control->reset_mask; 92 else 93 reset_state &= ~control->reset_mask; 94 95 ret = dev_ops->set_device_resets(sci, control->dev_id, reset_state); 96 out: 97 mutex_unlock(&control->lock); 98 99 return ret; 100 } 101 102 /** 103 * ti_sci_reset_assert() - assert device reset 104 * @rcdev: reset controller entity 105 * @id: ID of the reset to be asserted 106 * 107 * This function implements the reset driver op to assert a device's reset 108 * using the TI SCI protocol. This invokes the function ti_sci_reset_set() 109 * with the corresponding parameters as passed in, but with the @assert 110 * argument set to true for asserting the reset. 111 * 112 * Return: 0 for successful request, else a corresponding error value 113 */ 114 static int ti_sci_reset_assert(struct reset_controller_dev *rcdev, 115 unsigned long id) 116 { 117 return ti_sci_reset_set(rcdev, id, true); 118 } 119 120 /** 121 * ti_sci_reset_deassert() - deassert device reset 122 * @rcdev: reset controller entity 123 * @id: ID of the reset to be deasserted 124 * 125 * This function implements the reset driver op to deassert a device's reset 126 * using the TI SCI protocol. This invokes the function ti_sci_reset_set() 127 * with the corresponding parameters as passed in, but with the @assert 128 * argument set to false for deasserting the reset. 129 * 130 * Return: 0 for successful request, else a corresponding error value 131 */ 132 static int ti_sci_reset_deassert(struct reset_controller_dev *rcdev, 133 unsigned long id) 134 { 135 return ti_sci_reset_set(rcdev, id, false); 136 } 137 138 /** 139 * ti_sci_reset_status() - check device reset status 140 * @rcdev: reset controller entity 141 * @id: ID of reset to be checked 142 * 143 * This function implements the reset driver op to return the status of a 144 * device's reset using the TI SCI protocol. The reset register value is read 145 * by invoking the TI SCI device operation .get_device_resets(), and the 146 * status of the specific reset is extracted and returned using this reset's 147 * reset mask. 148 * 149 * Return: 0 if reset is deasserted, or a non-zero value if reset is asserted 150 */ 151 static int ti_sci_reset_status(struct reset_controller_dev *rcdev, 152 unsigned long id) 153 { 154 struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev); 155 const struct ti_sci_handle *sci = data->sci; 156 const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops; 157 struct ti_sci_reset_control *control; 158 u32 reset_state; 159 int ret; 160 161 control = idr_find(&data->idr, id); 162 if (!control) 163 return -EINVAL; 164 165 ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state); 166 if (ret) 167 return ret; 168 169 return reset_state & control->reset_mask; 170 } 171 172 static const struct reset_control_ops ti_sci_reset_ops = { 173 .assert = ti_sci_reset_assert, 174 .deassert = ti_sci_reset_deassert, 175 .status = ti_sci_reset_status, 176 }; 177 178 /** 179 * ti_sci_reset_of_xlate() - translate a set of OF arguments to a reset ID 180 * @rcdev: reset controller entity 181 * @reset_spec: OF reset argument specifier 182 * 183 * This function performs the translation of the reset argument specifier 184 * values defined in a reset consumer device node. The function allocates a 185 * reset control structure for that device reset, and will be used by the 186 * driver for performing any reset functions on that reset. An idr structure 187 * is allocated and used to map to the reset control structure. This idr 188 * is used by the driver to do reset lookups. 189 * 190 * Return: 0 for successful request, else a corresponding error value 191 */ 192 static int ti_sci_reset_of_xlate(struct reset_controller_dev *rcdev, 193 const struct of_phandle_args *reset_spec) 194 { 195 struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev); 196 struct ti_sci_reset_control *control; 197 198 if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells)) 199 return -EINVAL; 200 201 control = devm_kzalloc(data->dev, sizeof(*control), GFP_KERNEL); 202 if (!control) 203 return -ENOMEM; 204 205 control->dev_id = reset_spec->args[0]; 206 control->reset_mask = reset_spec->args[1]; 207 mutex_init(&control->lock); 208 209 return idr_alloc(&data->idr, control, 0, 0, GFP_KERNEL); 210 } 211 212 static const struct of_device_id ti_sci_reset_of_match[] = { 213 { .compatible = "ti,sci-reset", }, 214 { /* sentinel */ }, 215 }; 216 MODULE_DEVICE_TABLE(of, ti_sci_reset_of_match); 217 218 static int ti_sci_reset_probe(struct platform_device *pdev) 219 { 220 struct ti_sci_reset_data *data; 221 222 if (!pdev->dev.of_node) 223 return -ENODEV; 224 225 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); 226 if (!data) 227 return -ENOMEM; 228 229 data->sci = devm_ti_sci_get_handle(&pdev->dev); 230 if (IS_ERR(data->sci)) 231 return PTR_ERR(data->sci); 232 233 data->rcdev.ops = &ti_sci_reset_ops; 234 data->rcdev.owner = THIS_MODULE; 235 data->rcdev.of_node = pdev->dev.of_node; 236 data->rcdev.of_reset_n_cells = 2; 237 data->rcdev.of_xlate = ti_sci_reset_of_xlate; 238 data->dev = &pdev->dev; 239 idr_init(&data->idr); 240 241 platform_set_drvdata(pdev, data); 242 243 return reset_controller_register(&data->rcdev); 244 } 245 246 static int ti_sci_reset_remove(struct platform_device *pdev) 247 { 248 struct ti_sci_reset_data *data = platform_get_drvdata(pdev); 249 250 reset_controller_unregister(&data->rcdev); 251 252 idr_destroy(&data->idr); 253 254 return 0; 255 } 256 257 static struct platform_driver ti_sci_reset_driver = { 258 .probe = ti_sci_reset_probe, 259 .remove = ti_sci_reset_remove, 260 .driver = { 261 .name = "ti-sci-reset", 262 .of_match_table = ti_sci_reset_of_match, 263 }, 264 }; 265 module_platform_driver(ti_sci_reset_driver); 266 267 MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>"); 268 MODULE_DESCRIPTION("TI System Control Interface (TI SCI) Reset driver"); 269 MODULE_LICENSE("GPL v2"); 270