drivers/pmdomain/apple/pmgr-pwrstate.c

   1 // SPDX-License-Identifier: GPL-2.0-only OR MIT
   2 /*
   3  * Apple SoC PMGR device power state driver
   4  *
   5  * Copyright The Asahi Linux Contributors
   6  */
   7
   8 #include <linux/bitops.h>
   9 #include <linux/bitfield.h>
  10 #include <linux/err.h>
  11 #include <linux/of.h>
  12 #include <linux/of_address.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/pm_domain.h>
  15 #include <linux/regmap.h>
  16 #include <linux/mfd/syscon.h>
  17 #include <linux/reset-controller.h>
  18 #include <linux/module.h>
  19
  20 #define APPLE_PMGR_RESET        BIT(31)
  21 #define APPLE_PMGR_AUTO_ENABLE  BIT(28)
  22 #define APPLE_PMGR_PS_AUTO      GENMASK(27, 24)
  23 #define APPLE_PMGR_PS_MIN       GENMASK(19, 16)
  24 #define APPLE_PMGR_PARENT_OFF   BIT(11)
  25 #define APPLE_PMGR_DEV_DISABLE  BIT(10)
  26 #define APPLE_PMGR_WAS_CLKGATED BIT(9)
  27 #define APPLE_PMGR_WAS_PWRGATED BIT(8)
  28 #define APPLE_PMGR_PS_ACTUAL    GENMASK(7, 4)
  29 #define APPLE_PMGR_PS_TARGET    GENMASK(3, 0)
  30
  31 #define APPLE_PMGR_FLAGS        (APPLE_PMGR_WAS_CLKGATED | APPLE_PMGR_WAS_PWRGATED)
  32
  33 #define APPLE_PMGR_PS_ACTIVE    0xf
  34 #define APPLE_PMGR_PS_CLKGATE   0x4
  35 #define APPLE_PMGR_PS_PWRGATE   0x0
  36
  37 #define APPLE_PMGR_PS_SET_TIMEOUT 100
  38 #define APPLE_PMGR_RESET_TIME 1
  39
  40 struct apple_pmgr_ps {
  41         struct device *dev;
  42         struct generic_pm_domain genpd;
  43         struct reset_controller_dev rcdev;
  44         struct regmap *regmap;
  45         u32 offset;
  46         u32 min_state;
  47 };
  48
  49 #define genpd_to_apple_pmgr_ps(_genpd) container_of(_genpd, struct apple_pmgr_ps, genpd)
  50 #define rcdev_to_apple_pmgr_ps(_rcdev) container_of(_rcdev, struct apple_pmgr_ps, rcdev)
  51
  52 static int apple_pmgr_ps_set(struct generic_pm_domain *genpd, u32 pstate, bool auto_enable)
  53 {
  54         int ret;
  55         struct apple_pmgr_ps *ps = genpd_to_apple_pmgr_ps(genpd);
  56         u32 reg;
  57
  58         ret = regmap_read(ps->regmap, ps->offset, &reg);
  59         if (ret < 0)
  60                 return ret;
  61
  62         /* Resets are synchronous, and only work if the device is powered and clocked. */
  63         if (reg & APPLE_PMGR_RESET && pstate != APPLE_PMGR_PS_ACTIVE)
  64                 dev_err(ps->dev, "PS %s: powering off with RESET active\n",
  65                         genpd->name);
  66
  67         reg &= ~(APPLE_PMGR_AUTO_ENABLE | APPLE_PMGR_FLAGS | APPLE_PMGR_PS_TARGET);
  68         reg |= FIELD_PREP(APPLE_PMGR_PS_TARGET, pstate);
  69
  70         dev_dbg(ps->dev, "PS %s: pwrstate = 0x%x: 0x%x\n", genpd->name, pstate, reg);
  71
  72         regmap_write(ps->regmap, ps->offset, reg);
  73
  74         ret = regmap_read_poll_timeout_atomic(
  75                 ps->regmap, ps->offset, reg,
  76                 (FIELD_GET(APPLE_PMGR_PS_ACTUAL, reg) == pstate), 1,
  77                 APPLE_PMGR_PS_SET_TIMEOUT);
  78         if (ret < 0)
  79                 dev_err(ps->dev, "PS %s: Failed to reach power state 0x%x (now: 0x%x)\n",
  80                         genpd->name, pstate, reg);
  81
  82         if (auto_enable) {
  83                 /* Not all devices implement this; this is a no-op where not implemented. */
  84                 reg &= ~APPLE_PMGR_FLAGS;
  85                 reg |= APPLE_PMGR_AUTO_ENABLE;
  86                 regmap_write(ps->regmap, ps->offset, reg);
  87         }
  88
  89         return ret;
  90 }
  91
  92 static bool apple_pmgr_ps_is_active(struct apple_pmgr_ps *ps)
  93 {
  94         u32 reg = 0;
  95
  96         regmap_read(ps->regmap, ps->offset, &reg);
  97         /*
  98          * We consider domains as active if they are actually on, or if they have auto-PM
  99          * enabled and the intended target is on.
 100          */
 101         return (FIELD_GET(APPLE_PMGR_PS_ACTUAL, reg) == APPLE_PMGR_PS_ACTIVE ||
 102                 (FIELD_GET(APPLE_PMGR_PS_TARGET, reg) == APPLE_PMGR_PS_ACTIVE &&
 103                  reg & APPLE_PMGR_AUTO_ENABLE));
 104 }
 105
 106 static int apple_pmgr_ps_power_on(struct generic_pm_domain *genpd)
 107 {
 108         return apple_pmgr_ps_set(genpd, APPLE_PMGR_PS_ACTIVE, true);
 109 }
 110
 111 static int apple_pmgr_ps_power_off(struct generic_pm_domain *genpd)
 112 {
 113         return apple_pmgr_ps_set(genpd, APPLE_PMGR_PS_PWRGATE, false);
 114 }
 115
 116 static int apple_pmgr_reset_assert(struct reset_controller_dev *rcdev, unsigned long id)
 117 {
 118         struct apple_pmgr_ps *ps = rcdev_to_apple_pmgr_ps(rcdev);
 119         unsigned long flags;
 120
 121         spin_lock_irqsave(&ps->genpd.slock, flags);
 122
 123         if (ps->genpd.status == GENPD_STATE_OFF)
 124                 dev_err(ps->dev, "PS 0x%x: asserting RESET while powered down\n", ps->offset);
 125
 126         dev_dbg(ps->dev, "PS 0x%x: assert reset\n", ps->offset);
 127         /* Quiesce device before asserting reset */
 128         regmap_update_bits(ps->regmap, ps->offset, APPLE_PMGR_FLAGS | APPLE_PMGR_DEV_DISABLE,
 129                            APPLE_PMGR_DEV_DISABLE);
 130         regmap_update_bits(ps->regmap, ps->offset, APPLE_PMGR_FLAGS | APPLE_PMGR_RESET,
 131                            APPLE_PMGR_RESET);
 132
 133         spin_unlock_irqrestore(&ps->genpd.slock, flags);
 134
 135         return 0;
 136 }
 137
 138 static int apple_pmgr_reset_deassert(struct reset_controller_dev *rcdev, unsigned long id)
 139 {
 140         struct apple_pmgr_ps *ps = rcdev_to_apple_pmgr_ps(rcdev);
 141         unsigned long flags;
 142
 143         spin_lock_irqsave(&ps->genpd.slock, flags);
 144
 145         dev_dbg(ps->dev, "PS 0x%x: deassert reset\n", ps->offset);
 146         regmap_update_bits(ps->regmap, ps->offset, APPLE_PMGR_FLAGS | APPLE_PMGR_RESET, 0);
 147         regmap_update_bits(ps->regmap, ps->offset, APPLE_PMGR_FLAGS | APPLE_PMGR_DEV_DISABLE, 0);
 148
 149         if (ps->genpd.status == GENPD_STATE_OFF)
 150                 dev_err(ps->dev, "PS 0x%x: RESET was deasserted while powered down\n", ps->offset);
 151
 152         spin_unlock_irqrestore(&ps->genpd.slock, flags);
 153
 154         return 0;
 155 }
 156
 157 static int apple_pmgr_reset_reset(struct reset_controller_dev *rcdev, unsigned long id)
 158 {
 159         int ret;
 160
 161         ret = apple_pmgr_reset_assert(rcdev, id);
 162         if (ret)
 163                 return ret;
 164
 165         usleep_range(APPLE_PMGR_RESET_TIME, 2 * APPLE_PMGR_RESET_TIME);
 166
 167         return apple_pmgr_reset_deassert(rcdev, id);
 168 }
 169
 170 static int apple_pmgr_reset_status(struct reset_controller_dev *rcdev, unsigned long id)
 171 {
 172         struct apple_pmgr_ps *ps = rcdev_to_apple_pmgr_ps(rcdev);
 173         u32 reg = 0;
 174
 175         regmap_read(ps->regmap, ps->offset, &reg);
 176
 177         return !!(reg & APPLE_PMGR_RESET);
 178 }
 179
 180 static const struct reset_control_ops apple_pmgr_reset_ops = {
 181         .assert         = apple_pmgr_reset_assert,
 182         .deassert       = apple_pmgr_reset_deassert,
 183         .reset          = apple_pmgr_reset_reset,
 184         .status         = apple_pmgr_reset_status,
 185 };
 186
 187 static int apple_pmgr_reset_xlate(struct reset_controller_dev *rcdev,
 188                                   const struct of_phandle_args *reset_spec)
 189 {
 190         return 0;
 191 }
 192
 193 static int apple_pmgr_ps_probe(struct platform_device *pdev)
 194 {
 195         struct device *dev = &pdev->dev;
 196         struct device_node *node = dev->of_node;
 197         struct apple_pmgr_ps *ps;
 198         struct regmap *regmap;
 199         struct of_phandle_iterator it;
 200         int ret;
 201         const char *name;
 202         bool active;
 203
 204         regmap = syscon_node_to_regmap(node->parent);
 205         if (IS_ERR(regmap))
 206                 return PTR_ERR(regmap);
 207
 208         ps = devm_kzalloc(dev, sizeof(*ps), GFP_KERNEL);
 209         if (!ps)
 210                 return -ENOMEM;
 211
 212         ps->dev = dev;
 213         ps->regmap = regmap;
 214
 215         ret = of_property_read_string(node, "label", &name);
 216         if (ret < 0) {
 217                 dev_err(dev, "missing label property\n");
 218                 return ret;
 219         }
 220
 221         ret = of_property_read_u32(node, "reg", &ps->offset);
 222         if (ret < 0) {
 223                 dev_err(dev, "missing reg property\n");
 224                 return ret;
 225         }
 226
 227         ps->genpd.flags |= GENPD_FLAG_IRQ_SAFE;
 228         ps->genpd.name = name;
 229         ps->genpd.power_on = apple_pmgr_ps_power_on;
 230         ps->genpd.power_off = apple_pmgr_ps_power_off;
 231
 232         ret = of_property_read_u32(node, "apple,min-state", &ps->min_state);
 233         if (ret == 0 && ps->min_state <= APPLE_PMGR_PS_ACTIVE)
 234                 regmap_update_bits(regmap, ps->offset, APPLE_PMGR_FLAGS | APPLE_PMGR_PS_MIN,
 235                                    FIELD_PREP(APPLE_PMGR_PS_MIN, ps->min_state));
 236
 237         active = apple_pmgr_ps_is_active(ps);
 238         if (of_property_read_bool(node, "apple,always-on")) {
 239                 ps->genpd.flags |= GENPD_FLAG_ALWAYS_ON;
 240                 if (!active) {
 241                         dev_warn(dev, "always-on domain %s is not on at boot\n", name);
 242                         /* Turn it on so pm_genpd_init does not fail */
 243                         active = apple_pmgr_ps_power_on(&ps->genpd) == 0;
 244                 }
 245         }
 246
 247         /* Turn on auto-PM if the domain is already on */
 248         if (active)
 249                 regmap_update_bits(regmap, ps->offset, APPLE_PMGR_FLAGS | APPLE_PMGR_AUTO_ENABLE,
 250                                    APPLE_PMGR_AUTO_ENABLE);
 251
 252         ret = pm_genpd_init(&ps->genpd, NULL, !active);
 253         if (ret < 0) {
 254                 dev_err(dev, "pm_genpd_init failed\n");
 255                 return ret;
 256         }
 257
 258         ret = of_genpd_add_provider_simple(node, &ps->genpd);
 259         if (ret < 0) {
 260                 dev_err(dev, "of_genpd_add_provider_simple failed\n");
 261                 return ret;
 262         }
 263
 264         of_for_each_phandle(&it, ret, node, "power-domains", "#power-domain-cells", -1) {
 265                 struct of_phandle_args parent, child;
 266
 267                 parent.np = it.node;
 268                 parent.args_count = of_phandle_iterator_args(&it, parent.args, MAX_PHANDLE_ARGS);
 269                 child.np = node;
 270                 child.args_count = 0;
 271                 ret = of_genpd_add_subdomain(&parent, &child);
 272
 273                 if (ret == -EPROBE_DEFER) {
 274                         of_node_put(parent.np);
 275                         goto err_remove;
 276                 } else if (ret < 0) {
 277                         dev_err(dev, "failed to add to parent domain: %d (%s -> %s)\n",
 278                                 ret, it.node->name, node->name);
 279                         of_node_put(parent.np);
 280                         goto err_remove;
 281                 }
 282         }
 283
 284         /*
 285          * Do not participate in regular PM; parent power domains are handled via the
 286          * genpd hierarchy.
 287          */
 288         pm_genpd_remove_device(dev);
 289
 290         ps->rcdev.owner = THIS_MODULE;
 291         ps->rcdev.nr_resets = 1;
 292         ps->rcdev.ops = &apple_pmgr_reset_ops;
 293         ps->rcdev.of_node = dev->of_node;
 294         ps->rcdev.of_reset_n_cells = 0;
 295         ps->rcdev.of_xlate = apple_pmgr_reset_xlate;
 296
 297         ret = devm_reset_controller_register(dev, &ps->rcdev);
 298         if (ret < 0)
 299                 goto err_remove;
 300
 301         return 0;
 302 err_remove:
 303         of_genpd_del_provider(node);
 304         pm_genpd_remove(&ps->genpd);
 305         return ret;
 306 }
 307
 308 static const struct of_device_id apple_pmgr_ps_of_match[] = {
 309         { .compatible = "apple,pmgr-pwrstate" },
 310         {}
 311 };
 312
 313 MODULE_DEVICE_TABLE(of, apple_pmgr_ps_of_match);
 314
 315 static struct platform_driver apple_pmgr_ps_driver = {
 316         .probe = apple_pmgr_ps_probe,
 317         .driver = {
 318                 .name = "apple-pmgr-pwrstate",
 319                 .of_match_table = apple_pmgr_ps_of_match,
 320         },
 321 };
 322
 323 MODULE_AUTHOR("Hector Martin <marcan@marcan.st>");
 324 MODULE_DESCRIPTION("PMGR power state driver for Apple SoCs");
 325
 326 module_platform_driver(apple_pmgr_ps_driver);