drivers/regulator/scmi-regulator.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 //
   3 // System Control and Management Interface (SCMI) based regulator driver
   4 //
   5 // Copyright (C) 2020-2021 ARM Ltd.
   6 //
   7 // Implements a regulator driver on top of the SCMI Voltage Protocol.
   8 //
   9 // The ARM SCMI Protocol aims in general to hide as much as possible all the
  10 // underlying operational details while providing an abstracted interface for
  11 // its users to operate upon: as a consequence the resulting operational
  12 // capabilities and configurability of this regulator device are much more
  13 // limited than the ones usually available on a standard physical regulator.
  14 //
  15 // The supported SCMI regulator ops are restricted to the bare minimum:
  16 //
  17 //  - 'status_ops': enable/disable/is_enabled
  18 //  - 'voltage_ops': get_voltage_sel/set_voltage_sel
  19 //                   list_voltage/map_voltage
  20 //
  21 // Each SCMI regulator instance is associated, through the means of a proper DT
  22 // entry description, to a specific SCMI Voltage Domain.
  23
  24 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  25
  26 #include <linux/linear_range.h>
  27 #include <linux/module.h>
  28 #include <linux/of.h>
  29 #include <linux/regulator/driver.h>
  30 #include <linux/regulator/machine.h>
  31 #include <linux/regulator/of_regulator.h>
  32 #include <linux/scmi_protocol.h>
  33 #include <linux/slab.h>
  34 #include <linux/types.h>
  35
  36 static const struct scmi_voltage_proto_ops *voltage_ops;
  37
  38 struct scmi_regulator {
  39         u32 id;
  40         struct scmi_device *sdev;
  41         struct scmi_protocol_handle *ph;
  42         struct regulator_dev *rdev;
  43         struct device_node *of_node;
  44         struct regulator_desc desc;
  45         struct regulator_config conf;
  46 };
  47
  48 struct scmi_regulator_info {
  49         int num_doms;
  50         struct scmi_regulator **sregv;
  51 };
  52
  53 static int scmi_reg_enable(struct regulator_dev *rdev)
  54 {
  55         struct scmi_regulator *sreg = rdev_get_drvdata(rdev);
  56
  57         return voltage_ops->config_set(sreg->ph, sreg->id,
  58                                        SCMI_VOLTAGE_ARCH_STATE_ON);
  59 }
  60
  61 static int scmi_reg_disable(struct regulator_dev *rdev)
  62 {
  63         struct scmi_regulator *sreg = rdev_get_drvdata(rdev);
  64
  65         return voltage_ops->config_set(sreg->ph, sreg->id,
  66                                        SCMI_VOLTAGE_ARCH_STATE_OFF);
  67 }
  68
  69 static int scmi_reg_is_enabled(struct regulator_dev *rdev)
  70 {
  71         int ret;
  72         u32 config;
  73         struct scmi_regulator *sreg = rdev_get_drvdata(rdev);
  74
  75         ret = voltage_ops->config_get(sreg->ph, sreg->id, &config);
  76         if (ret) {
  77                 dev_err(&sreg->sdev->dev,
  78                         "Error %d reading regulator %s status.\n",
  79                         ret, sreg->desc.name);
  80                 return ret;
  81         }
  82
  83         return config & SCMI_VOLTAGE_ARCH_STATE_ON;
  84 }
  85
  86 static int scmi_reg_get_voltage_sel(struct regulator_dev *rdev)
  87 {
  88         int ret;
  89         s32 volt_uV;
  90         struct scmi_regulator *sreg = rdev_get_drvdata(rdev);
  91
  92         ret = voltage_ops->level_get(sreg->ph, sreg->id, &volt_uV);
  93         if (ret)
  94                 return ret;
  95
  96         return sreg->desc.ops->map_voltage(rdev, volt_uV, volt_uV);
  97 }
  98
  99 static int scmi_reg_set_voltage_sel(struct regulator_dev *rdev,
 100                                     unsigned int selector)
 101 {
 102         s32 volt_uV;
 103         struct scmi_regulator *sreg = rdev_get_drvdata(rdev);
 104
 105         volt_uV = sreg->desc.ops->list_voltage(rdev, selector);
 106         if (volt_uV <= 0)
 107                 return -EINVAL;
 108
 109         return voltage_ops->level_set(sreg->ph, sreg->id, 0x0, volt_uV);
 110 }
 111
 112 static const struct regulator_ops scmi_reg_fixed_ops = {
 113         .enable = scmi_reg_enable,
 114         .disable = scmi_reg_disable,
 115         .is_enabled = scmi_reg_is_enabled,
 116 };
 117
 118 static const struct regulator_ops scmi_reg_linear_ops = {
 119         .enable = scmi_reg_enable,
 120         .disable = scmi_reg_disable,
 121         .is_enabled = scmi_reg_is_enabled,
 122         .get_voltage_sel = scmi_reg_get_voltage_sel,
 123         .set_voltage_sel = scmi_reg_set_voltage_sel,
 124         .list_voltage = regulator_list_voltage_linear,
 125         .map_voltage = regulator_map_voltage_linear,
 126 };
 127
 128 static const struct regulator_ops scmi_reg_discrete_ops = {
 129         .enable = scmi_reg_enable,
 130         .disable = scmi_reg_disable,
 131         .is_enabled = scmi_reg_is_enabled,
 132         .get_voltage_sel = scmi_reg_get_voltage_sel,
 133         .set_voltage_sel = scmi_reg_set_voltage_sel,
 134         .list_voltage = regulator_list_voltage_table,
 135         .map_voltage = regulator_map_voltage_iterate,
 136 };
 137
 138 static int
 139 scmi_config_linear_regulator_mappings(struct scmi_regulator *sreg,
 140                                       const struct scmi_voltage_info *vinfo)
 141 {
 142         s32 delta_uV;
 143
 144         /*
 145          * Note that SCMI voltage domains describable by linear ranges
 146          * (segments) {low, high, step} are guaranteed to come in one single
 147          * triplet by the SCMI Voltage Domain protocol support itself.
 148          */
 149
 150         delta_uV = (vinfo->levels_uv[SCMI_VOLTAGE_SEGMENT_HIGH] -
 151                         vinfo->levels_uv[SCMI_VOLTAGE_SEGMENT_LOW]);
 152
 153         /* Rule out buggy negative-intervals answers from fw */
 154         if (delta_uV < 0) {
 155                 dev_err(&sreg->sdev->dev,
 156                         "Invalid volt-range %d-%duV for domain %d\n",
 157                         vinfo->levels_uv[SCMI_VOLTAGE_SEGMENT_LOW],
 158                         vinfo->levels_uv[SCMI_VOLTAGE_SEGMENT_HIGH],
 159                         sreg->id);
 160                 return -EINVAL;
 161         }
 162
 163         if (!delta_uV) {
 164                 /* Just one fixed voltage exposed by SCMI */
 165                 sreg->desc.fixed_uV =
 166                         vinfo->levels_uv[SCMI_VOLTAGE_SEGMENT_LOW];
 167                 sreg->desc.n_voltages = 1;
 168                 sreg->desc.ops = &scmi_reg_fixed_ops;
 169         } else {
 170                 /* One simple linear mapping. */
 171                 sreg->desc.min_uV =
 172                         vinfo->levels_uv[SCMI_VOLTAGE_SEGMENT_LOW];
 173                 sreg->desc.uV_step =
 174                         vinfo->levels_uv[SCMI_VOLTAGE_SEGMENT_STEP];
 175                 sreg->desc.linear_min_sel = 0;
 176                 sreg->desc.n_voltages = (delta_uV / sreg->desc.uV_step) + 1;
 177                 sreg->desc.ops = &scmi_reg_linear_ops;
 178         }
 179
 180         return 0;
 181 }
 182
 183 static int
 184 scmi_config_discrete_regulator_mappings(struct scmi_regulator *sreg,
 185                                         const struct scmi_voltage_info *vinfo)
 186 {
 187         /* Discrete non linear levels are mapped to volt_table */
 188         sreg->desc.n_voltages = vinfo->num_levels;
 189
 190         if (sreg->desc.n_voltages > 1) {
 191                 sreg->desc.volt_table = (const unsigned int *)vinfo->levels_uv;
 192                 sreg->desc.ops = &scmi_reg_discrete_ops;
 193         } else {
 194                 sreg->desc.fixed_uV = vinfo->levels_uv[0];
 195                 sreg->desc.ops = &scmi_reg_fixed_ops;
 196         }
 197
 198         return 0;
 199 }
 200
 201 static int scmi_regulator_common_init(struct scmi_regulator *sreg)
 202 {
 203         int ret;
 204         struct device *dev = &sreg->sdev->dev;
 205         const struct scmi_voltage_info *vinfo;
 206
 207         vinfo = voltage_ops->info_get(sreg->ph, sreg->id);
 208         if (!vinfo) {
 209                 dev_warn(dev, "Failure to get voltage domain %d\n",
 210                          sreg->id);
 211                 return -ENODEV;
 212         }
 213
 214         /*
 215          * Regulator framework does not fully support negative voltages
 216          * so we discard any voltage domain reported as supporting negative
 217          * voltages: as a consequence each levels_uv entry is guaranteed to
 218          * be non-negative from here on.
 219          */
 220         if (vinfo->negative_volts_allowed) {
 221                 dev_warn(dev, "Negative voltages NOT supported...skip %s\n",
 222                          sreg->of_node->full_name);
 223                 return -EOPNOTSUPP;
 224         }
 225
 226         sreg->desc.name = devm_kasprintf(dev, GFP_KERNEL, "%s", vinfo->name);
 227         if (!sreg->desc.name)
 228                 return -ENOMEM;
 229
 230         sreg->desc.id = sreg->id;
 231         sreg->desc.type = REGULATOR_VOLTAGE;
 232         sreg->desc.owner = THIS_MODULE;
 233         sreg->desc.of_match_full_name = true;
 234         sreg->desc.of_match = sreg->of_node->full_name;
 235         sreg->desc.regulators_node = "regulators";
 236         if (vinfo->segmented)
 237                 ret = scmi_config_linear_regulator_mappings(sreg, vinfo);
 238         else
 239                 ret = scmi_config_discrete_regulator_mappings(sreg, vinfo);
 240         if (ret)
 241                 return ret;
 242
 243         /*
 244          * Using the scmi device here to have DT searched from Voltage
 245          * protocol node down.
 246          */
 247         sreg->conf.dev = dev;
 248
 249         /* Store for later retrieval via rdev_get_drvdata() */
 250         sreg->conf.driver_data = sreg;
 251
 252         return 0;
 253 }
 254
 255 static int process_scmi_regulator_of_node(struct scmi_device *sdev,
 256                                           struct scmi_protocol_handle *ph,
 257                                           struct device_node *np,
 258                                           struct scmi_regulator_info *rinfo)
 259 {
 260         u32 dom, ret;
 261
 262         ret = of_property_read_u32(np, "reg", &dom);
 263         if (ret)
 264                 return ret;
 265
 266         if (dom >= rinfo->num_doms)
 267                 return -ENODEV;
 268
 269         if (rinfo->sregv[dom]) {
 270                 dev_err(&sdev->dev,
 271                         "SCMI Voltage Domain %d already in use. Skipping: %s\n",
 272                         dom, np->full_name);
 273                 return -EINVAL;
 274         }
 275
 276         rinfo->sregv[dom] = devm_kzalloc(&sdev->dev,
 277                                          sizeof(struct scmi_regulator),
 278                                          GFP_KERNEL);
 279         if (!rinfo->sregv[dom])
 280                 return -ENOMEM;
 281
 282         rinfo->sregv[dom]->id = dom;
 283         rinfo->sregv[dom]->sdev = sdev;
 284         rinfo->sregv[dom]->ph = ph;
 285
 286         /* get hold of good nodes */
 287         of_node_get(np);
 288         rinfo->sregv[dom]->of_node = np;
 289
 290         dev_dbg(&sdev->dev,
 291                 "Found SCMI Regulator entry -- OF node [%d] -> %s\n",
 292                 dom, np->full_name);
 293
 294         return 0;
 295 }
 296
 297 static int scmi_regulator_probe(struct scmi_device *sdev)
 298 {
 299         int d, ret, num_doms;
 300         struct device_node *np;
 301         const struct scmi_handle *handle = sdev->handle;
 302         struct scmi_regulator_info *rinfo;
 303         struct scmi_protocol_handle *ph;
 304
 305         if (!handle)
 306                 return -ENODEV;
 307
 308         voltage_ops = handle->devm_protocol_get(sdev,
 309                                                 SCMI_PROTOCOL_VOLTAGE, &ph);
 310         if (IS_ERR(voltage_ops))
 311                 return PTR_ERR(voltage_ops);
 312
 313         num_doms = voltage_ops->num_domains_get(ph);
 314         if (!num_doms)
 315                 return 0;
 316
 317         if (num_doms < 0) {
 318                 dev_err(&sdev->dev, "failed to get voltage domains - err:%d\n",
 319                         num_doms);
 320
 321                 return num_doms;
 322         }
 323
 324         rinfo = devm_kzalloc(&sdev->dev, sizeof(*rinfo), GFP_KERNEL);
 325         if (!rinfo)
 326                 return -ENOMEM;
 327
 328         /* Allocate pointers array for all possible domains */
 329         rinfo->sregv = devm_kcalloc(&sdev->dev, num_doms,
 330                                     sizeof(void *), GFP_KERNEL);
 331         if (!rinfo->sregv)
 332                 return -ENOMEM;
 333
 334         rinfo->num_doms = num_doms;
 335
 336         /*
 337          * Start collecting into rinfo->sregv possibly good SCMI Regulators as
 338          * described by a well-formed DT entry and associated with an existing
 339          * plausible SCMI Voltage Domain number, all belonging to this SCMI
 340          * platform instance node (handle->dev->of_node).
 341          */
 342         of_node_get(handle->dev->of_node);
 343         np = of_find_node_by_name(handle->dev->of_node, "regulators");
 344         for_each_child_of_node_scoped(np, child) {
 345                 ret = process_scmi_regulator_of_node(sdev, ph, child, rinfo);
 346                 /* abort on any mem issue */
 347                 if (ret == -ENOMEM)
 348                         return ret;
 349         }
 350         of_node_put(np);
 351         /*
 352          * Register a regulator for each valid regulator-DT-entry that we
 353          * can successfully reach via SCMI and has a valid associated voltage
 354          * domain.
 355          */
 356         for (d = 0; d < num_doms; d++) {
 357                 struct scmi_regulator *sreg = rinfo->sregv[d];
 358
 359                 /* Skip empty slots */
 360                 if (!sreg)
 361                         continue;
 362
 363                 ret = scmi_regulator_common_init(sreg);
 364                 /* Skip invalid voltage domains */
 365                 if (ret)
 366                         continue;
 367
 368                 sreg->rdev = devm_regulator_register(&sdev->dev, &sreg->desc,
 369                                                      &sreg->conf);
 370                 if (IS_ERR(sreg->rdev)) {
 371                         sreg->rdev = NULL;
 372                         continue;
 373                 }
 374
 375                 dev_info(&sdev->dev,
 376                          "Regulator %s registered for domain [%d]\n",
 377                          sreg->desc.name, sreg->id);
 378         }
 379
 380         dev_set_drvdata(&sdev->dev, rinfo);
 381
 382         return 0;
 383 }
 384
 385 static void scmi_regulator_remove(struct scmi_device *sdev)
 386 {
 387         int d;
 388         struct scmi_regulator_info *rinfo;
 389
 390         rinfo = dev_get_drvdata(&sdev->dev);
 391         if (!rinfo)
 392                 return;
 393
 394         for (d = 0; d < rinfo->num_doms; d++) {
 395                 if (!rinfo->sregv[d])
 396                         continue;
 397                 of_node_put(rinfo->sregv[d]->of_node);
 398         }
 399 }
 400
 401 static const struct scmi_device_id scmi_regulator_id_table[] = {
 402         { SCMI_PROTOCOL_VOLTAGE,  "regulator" },
 403         { },
 404 };
 405 MODULE_DEVICE_TABLE(scmi, scmi_regulator_id_table);
 406
 407 static struct scmi_driver scmi_drv = {
 408         .name           = "scmi-regulator",
 409         .probe          = scmi_regulator_probe,
 410         .remove         = scmi_regulator_remove,
 411         .id_table       = scmi_regulator_id_table,
 412 };
 413
 414 module_scmi_driver(scmi_drv);
 415
 416 MODULE_AUTHOR("Cristian Marussi <cristian.marussi@arm.com>");
 417 MODULE_DESCRIPTION("ARM SCMI regulator driver");
 418 MODULE_LICENSE("GPL v2");