drivers/clk/bcm/clk-raspberrypi.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Raspberry Pi driver for firmware controlled clocks
   4  *
   5  * Even though clk-bcm2835 provides an interface to the hardware registers for
   6  * the system clocks we've had to factor out 'pllb' as the firmware 'owns' it.
   7  * We're not allowed to change it directly as we might race with the
   8  * over-temperature and under-voltage protections provided by the firmware.
   9  *
  10  * Copyright (C) 2019 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
  11  */
  12
  13 #include <linux/clkdev.h>
  14 #include <linux/clk-provider.h>
  15 #include <linux/io.h>
  16 #include <linux/module.h>
  17 #include <linux/platform_device.h>
  18
  19 #include <soc/bcm2835/raspberrypi-firmware.h>
  20
  21 enum rpi_firmware_clk_id {
  22         RPI_FIRMWARE_EMMC_CLK_ID = 1,
  23         RPI_FIRMWARE_UART_CLK_ID,
  24         RPI_FIRMWARE_ARM_CLK_ID,
  25         RPI_FIRMWARE_CORE_CLK_ID,
  26         RPI_FIRMWARE_V3D_CLK_ID,
  27         RPI_FIRMWARE_H264_CLK_ID,
  28         RPI_FIRMWARE_ISP_CLK_ID,
  29         RPI_FIRMWARE_SDRAM_CLK_ID,
  30         RPI_FIRMWARE_PIXEL_CLK_ID,
  31         RPI_FIRMWARE_PWM_CLK_ID,
  32         RPI_FIRMWARE_HEVC_CLK_ID,
  33         RPI_FIRMWARE_EMMC2_CLK_ID,
  34         RPI_FIRMWARE_M2MC_CLK_ID,
  35         RPI_FIRMWARE_PIXEL_BVB_CLK_ID,
  36         RPI_FIRMWARE_VEC_CLK_ID,
  37         RPI_FIRMWARE_NUM_CLK_ID,
  38 };
  39
  40 static char *rpi_firmware_clk_names[] = {
  41         [RPI_FIRMWARE_EMMC_CLK_ID]      = "emmc",
  42         [RPI_FIRMWARE_UART_CLK_ID]      = "uart",
  43         [RPI_FIRMWARE_ARM_CLK_ID]       = "arm",
  44         [RPI_FIRMWARE_CORE_CLK_ID]      = "core",
  45         [RPI_FIRMWARE_V3D_CLK_ID]       = "v3d",
  46         [RPI_FIRMWARE_H264_CLK_ID]      = "h264",
  47         [RPI_FIRMWARE_ISP_CLK_ID]       = "isp",
  48         [RPI_FIRMWARE_SDRAM_CLK_ID]     = "sdram",
  49         [RPI_FIRMWARE_PIXEL_CLK_ID]     = "pixel",
  50         [RPI_FIRMWARE_PWM_CLK_ID]       = "pwm",
  51         [RPI_FIRMWARE_HEVC_CLK_ID]      = "hevc",
  52         [RPI_FIRMWARE_EMMC2_CLK_ID]     = "emmc2",
  53         [RPI_FIRMWARE_M2MC_CLK_ID]      = "m2mc",
  54         [RPI_FIRMWARE_PIXEL_BVB_CLK_ID] = "pixel-bvb",
  55         [RPI_FIRMWARE_VEC_CLK_ID]       = "vec",
  56 };
  57
  58 #define RPI_FIRMWARE_STATE_ENABLE_BIT   BIT(0)
  59 #define RPI_FIRMWARE_STATE_WAIT_BIT     BIT(1)
  60
  61 struct raspberrypi_clk_variant;
  62
  63 struct raspberrypi_clk {
  64         struct device *dev;
  65         struct rpi_firmware *firmware;
  66         struct platform_device *cpufreq;
  67 };
  68
  69 struct raspberrypi_clk_data {
  70         struct clk_hw hw;
  71
  72         unsigned int id;
  73         struct raspberrypi_clk_variant *variant;
  74
  75         struct raspberrypi_clk *rpi;
  76 };
  77
  78 struct raspberrypi_clk_variant {
  79         bool            export;
  80         char            *clkdev;
  81         unsigned long   min_rate;
  82         bool            minimize;
  83 };
  84
  85 static struct raspberrypi_clk_variant
  86 raspberrypi_clk_variants[RPI_FIRMWARE_NUM_CLK_ID] = {
  87         [RPI_FIRMWARE_ARM_CLK_ID] = {
  88                 .export = true,
  89                 .clkdev = "cpu0",
  90         },
  91         [RPI_FIRMWARE_CORE_CLK_ID] = {
  92                 .export = true,
  93
  94                 /*
  95                  * The clock is shared between the HVS and the CSI
  96                  * controllers, on the BCM2711 and will change depending
  97                  * on the pixels composited on the HVS and the capture
  98                  * resolution on Unicam.
  99                  *
 100                  * Since the rate can get quite large, and we need to
 101                  * coordinate between both driver instances, let's
 102                  * always use the minimum the drivers will let us.
 103                  */
 104                 .minimize = true,
 105         },
 106         [RPI_FIRMWARE_M2MC_CLK_ID] = {
 107                 .export = true,
 108
 109                 /*
 110                  * If we boot without any cable connected to any of the
 111                  * HDMI connector, the firmware will skip the HSM
 112                  * initialization and leave it with a rate of 0,
 113                  * resulting in a bus lockup when we're accessing the
 114                  * registers even if it's enabled.
 115                  *
 116                  * Let's put a sensible default so that we don't end up
 117                  * in this situation.
 118                  */
 119                 .min_rate = 120000000,
 120
 121                 /*
 122                  * The clock is shared between the two HDMI controllers
 123                  * on the BCM2711 and will change depending on the
 124                  * resolution output on each. Since the rate can get
 125                  * quite large, and we need to coordinate between both
 126                  * driver instances, let's always use the minimum the
 127                  * drivers will let us.
 128                  */
 129                 .minimize = true,
 130         },
 131         [RPI_FIRMWARE_V3D_CLK_ID] = {
 132                 .export = true,
 133         },
 134         [RPI_FIRMWARE_PIXEL_CLK_ID] = {
 135                 .export = true,
 136         },
 137         [RPI_FIRMWARE_HEVC_CLK_ID] = {
 138                 .export = true,
 139         },
 140         [RPI_FIRMWARE_PIXEL_BVB_CLK_ID] = {
 141                 .export = true,
 142         },
 143         [RPI_FIRMWARE_VEC_CLK_ID] = {
 144                 .export = true,
 145         },
 146 };
 147
 148 /*
 149  * Structure of the message passed to Raspberry Pi's firmware in order to
 150  * change clock rates. The 'disable_turbo' option is only available to the ARM
 151  * clock (pllb) which we enable by default as turbo mode will alter multiple
 152  * clocks at once.
 153  *
 154  * Even though we're able to access the clock registers directly we're bound to
 155  * use the firmware interface as the firmware ultimately takes care of
 156  * mitigating overheating/undervoltage situations and we would be changing
 157  * frequencies behind his back.
 158  *
 159  * For more information on the firmware interface check:
 160  * https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface
 161  */
 162 struct raspberrypi_firmware_prop {
 163         __le32 id;
 164         __le32 val;
 165         __le32 disable_turbo;
 166 } __packed;
 167
 168 static int raspberrypi_clock_property(struct rpi_firmware *firmware,
 169                                       const struct raspberrypi_clk_data *data,
 170                                       u32 tag, u32 *val)
 171 {
 172         struct raspberrypi_firmware_prop msg = {
 173                 .id = cpu_to_le32(data->id),
 174                 .val = cpu_to_le32(*val),
 175                 .disable_turbo = cpu_to_le32(1),
 176         };
 177         int ret;
 178
 179         ret = rpi_firmware_property(firmware, tag, &msg, sizeof(msg));
 180         if (ret)
 181                 return ret;
 182
 183         *val = le32_to_cpu(msg.val);
 184
 185         return 0;
 186 }
 187
 188 static int raspberrypi_fw_is_prepared(struct clk_hw *hw)
 189 {
 190         struct raspberrypi_clk_data *data =
 191                 container_of(hw, struct raspberrypi_clk_data, hw);
 192         struct raspberrypi_clk *rpi = data->rpi;
 193         u32 val = 0;
 194         int ret;
 195
 196         ret = raspberrypi_clock_property(rpi->firmware, data,
 197                                          RPI_FIRMWARE_GET_CLOCK_STATE, &val);
 198         if (ret)
 199                 return 0;
 200
 201         return !!(val & RPI_FIRMWARE_STATE_ENABLE_BIT);
 202 }
 203
 204
 205 static unsigned long raspberrypi_fw_get_rate(struct clk_hw *hw,
 206                                              unsigned long parent_rate)
 207 {
 208         struct raspberrypi_clk_data *data =
 209                 container_of(hw, struct raspberrypi_clk_data, hw);
 210         struct raspberrypi_clk *rpi = data->rpi;
 211         u32 val = 0;
 212         int ret;
 213
 214         ret = raspberrypi_clock_property(rpi->firmware, data,
 215                                          RPI_FIRMWARE_GET_CLOCK_RATE, &val);
 216         if (ret)
 217                 return 0;
 218
 219         return val;
 220 }
 221
 222 static int raspberrypi_fw_set_rate(struct clk_hw *hw, unsigned long rate,
 223                                    unsigned long parent_rate)
 224 {
 225         struct raspberrypi_clk_data *data =
 226                 container_of(hw, struct raspberrypi_clk_data, hw);
 227         struct raspberrypi_clk *rpi = data->rpi;
 228         u32 _rate = rate;
 229         int ret;
 230
 231         ret = raspberrypi_clock_property(rpi->firmware, data,
 232                                          RPI_FIRMWARE_SET_CLOCK_RATE, &_rate);
 233         if (ret)
 234                 dev_err_ratelimited(rpi->dev, "Failed to change %s frequency: %d\n",
 235                                     clk_hw_get_name(hw), ret);
 236
 237         return ret;
 238 }
 239
 240 static int raspberrypi_fw_dumb_determine_rate(struct clk_hw *hw,
 241                                               struct clk_rate_request *req)
 242 {
 243         struct raspberrypi_clk_data *data =
 244                 container_of(hw, struct raspberrypi_clk_data, hw);
 245         struct raspberrypi_clk_variant *variant = data->variant;
 246
 247         /*
 248          * The firmware will do the rounding but that isn't part of
 249          * the interface with the firmware, so we just do our best
 250          * here.
 251          */
 252
 253         req->rate = clamp(req->rate, req->min_rate, req->max_rate);
 254
 255         /*
 256          * We want to aggressively reduce the clock rate here, so let's
 257          * just ignore the requested rate and return the bare minimum
 258          * rate we can get away with.
 259          */
 260         if (variant->minimize && req->min_rate > 0)
 261                 req->rate = req->min_rate;
 262
 263         return 0;
 264 }
 265
 266 static const struct clk_ops raspberrypi_firmware_clk_ops = {
 267         .is_prepared    = raspberrypi_fw_is_prepared,
 268         .recalc_rate    = raspberrypi_fw_get_rate,
 269         .determine_rate = raspberrypi_fw_dumb_determine_rate,
 270         .set_rate       = raspberrypi_fw_set_rate,
 271 };
 272
 273 static struct clk_hw *raspberrypi_clk_register(struct raspberrypi_clk *rpi,
 274                                                unsigned int parent,
 275                                                unsigned int id,
 276                                                struct raspberrypi_clk_variant *variant)
 277 {
 278         struct raspberrypi_clk_data *data;
 279         struct clk_init_data init = {};
 280         u32 min_rate, max_rate;
 281         int ret;
 282
 283         data = devm_kzalloc(rpi->dev, sizeof(*data), GFP_KERNEL);
 284         if (!data)
 285                 return ERR_PTR(-ENOMEM);
 286         data->rpi = rpi;
 287         data->id = id;
 288         data->variant = variant;
 289
 290         init.name = devm_kasprintf(rpi->dev, GFP_KERNEL,
 291                                    "fw-clk-%s",
 292                                    rpi_firmware_clk_names[id]);
 293         init.ops = &raspberrypi_firmware_clk_ops;
 294         init.flags = CLK_GET_RATE_NOCACHE;
 295
 296         data->hw.init = &init;
 297
 298         ret = raspberrypi_clock_property(rpi->firmware, data,
 299                                          RPI_FIRMWARE_GET_MIN_CLOCK_RATE,
 300                                          &min_rate);
 301         if (ret) {
 302                 dev_err(rpi->dev, "Failed to get clock %d min freq: %d\n",
 303                         id, ret);
 304                 return ERR_PTR(ret);
 305         }
 306
 307         ret = raspberrypi_clock_property(rpi->firmware, data,
 308                                          RPI_FIRMWARE_GET_MAX_CLOCK_RATE,
 309                                          &max_rate);
 310         if (ret) {
 311                 dev_err(rpi->dev, "Failed to get clock %d max freq: %d\n",
 312                         id, ret);
 313                 return ERR_PTR(ret);
 314         }
 315
 316         ret = devm_clk_hw_register(rpi->dev, &data->hw);
 317         if (ret)
 318                 return ERR_PTR(ret);
 319
 320         clk_hw_set_rate_range(&data->hw, min_rate, max_rate);
 321
 322         if (variant->clkdev) {
 323                 ret = devm_clk_hw_register_clkdev(rpi->dev, &data->hw,
 324                                                   NULL, variant->clkdev);
 325                 if (ret) {
 326                         dev_err(rpi->dev, "Failed to initialize clkdev\n");
 327                         return ERR_PTR(ret);
 328                 }
 329         }
 330
 331         if (variant->min_rate) {
 332                 unsigned long rate;
 333
 334                 clk_hw_set_rate_range(&data->hw, variant->min_rate, max_rate);
 335
 336                 rate = raspberrypi_fw_get_rate(&data->hw, 0);
 337                 if (rate < variant->min_rate) {
 338                         ret = raspberrypi_fw_set_rate(&data->hw, variant->min_rate, 0);
 339                         if (ret)
 340                                 return ERR_PTR(ret);
 341                 }
 342         }
 343
 344         return &data->hw;
 345 }
 346
 347 struct rpi_firmware_get_clocks_response {
 348         u32 parent;
 349         u32 id;
 350 };
 351
 352 static int raspberrypi_discover_clocks(struct raspberrypi_clk *rpi,
 353                                        struct clk_hw_onecell_data *data)
 354 {
 355         struct rpi_firmware_get_clocks_response *clks;
 356         int ret;
 357
 358         /*
 359          * The firmware doesn't guarantee that the last element of
 360          * RPI_FIRMWARE_GET_CLOCKS is zeroed. So allocate an additional
 361          * zero element as sentinel.
 362          */
 363         clks = devm_kcalloc(rpi->dev,
 364                             RPI_FIRMWARE_NUM_CLK_ID + 1, sizeof(*clks),
 365                             GFP_KERNEL);
 366         if (!clks)
 367                 return -ENOMEM;
 368
 369         ret = rpi_firmware_property(rpi->firmware, RPI_FIRMWARE_GET_CLOCKS,
 370                                     clks,
 371                                     sizeof(*clks) * RPI_FIRMWARE_NUM_CLK_ID);
 372         if (ret)
 373                 return ret;
 374
 375         while (clks->id) {
 376                 struct raspberrypi_clk_variant *variant;
 377
 378                 if (clks->id > RPI_FIRMWARE_NUM_CLK_ID) {
 379                         dev_err(rpi->dev, "Unknown clock id: %u (max: %u)\n",
 380                                            clks->id, RPI_FIRMWARE_NUM_CLK_ID);
 381                         return -EINVAL;
 382                 }
 383
 384                 variant = &raspberrypi_clk_variants[clks->id];
 385                 if (variant->export) {
 386                         struct clk_hw *hw;
 387
 388                         hw = raspberrypi_clk_register(rpi, clks->parent,
 389                                                       clks->id, variant);
 390                         if (IS_ERR(hw))
 391                                 return PTR_ERR(hw);
 392
 393                         data->hws[clks->id] = hw;
 394                         data->num = clks->id + 1;
 395                 }
 396
 397                 clks++;
 398         }
 399
 400         return 0;
 401 }
 402
 403 static int raspberrypi_clk_probe(struct platform_device *pdev)
 404 {
 405         struct clk_hw_onecell_data *clk_data;
 406         struct device_node *firmware_node;
 407         struct device *dev = &pdev->dev;
 408         struct rpi_firmware *firmware;
 409         struct raspberrypi_clk *rpi;
 410         int ret;
 411
 412         /*
 413          * We can be probed either through the an old-fashioned
 414          * platform device registration or through a DT node that is a
 415          * child of the firmware node. Handle both cases.
 416          */
 417         if (dev->of_node)
 418                 firmware_node = of_get_parent(dev->of_node);
 419         else
 420                 firmware_node = of_find_compatible_node(NULL, NULL,
 421                                                         "raspberrypi,bcm2835-firmware");
 422         if (!firmware_node) {
 423                 dev_err(dev, "Missing firmware node\n");
 424                 return -ENOENT;
 425         }
 426
 427         firmware = devm_rpi_firmware_get(&pdev->dev, firmware_node);
 428         of_node_put(firmware_node);
 429         if (!firmware)
 430                 return -EPROBE_DEFER;
 431
 432         rpi = devm_kzalloc(dev, sizeof(*rpi), GFP_KERNEL);
 433         if (!rpi)
 434                 return -ENOMEM;
 435
 436         rpi->dev = dev;
 437         rpi->firmware = firmware;
 438         platform_set_drvdata(pdev, rpi);
 439
 440         clk_data = devm_kzalloc(dev, struct_size(clk_data, hws,
 441                                                  RPI_FIRMWARE_NUM_CLK_ID),
 442                                 GFP_KERNEL);
 443         if (!clk_data)
 444                 return -ENOMEM;
 445
 446         ret = raspberrypi_discover_clocks(rpi, clk_data);
 447         if (ret)
 448                 return ret;
 449
 450         ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
 451                                           clk_data);
 452         if (ret)
 453                 return ret;
 454
 455         rpi->cpufreq = platform_device_register_data(dev, "raspberrypi-cpufreq",
 456                                                      -1, NULL, 0);
 457
 458         return 0;
 459 }
 460
 461 static int raspberrypi_clk_remove(struct platform_device *pdev)
 462 {
 463         struct raspberrypi_clk *rpi = platform_get_drvdata(pdev);
 464
 465         platform_device_unregister(rpi->cpufreq);
 466
 467         return 0;
 468 }
 469
 470 static const struct of_device_id raspberrypi_clk_match[] = {
 471         { .compatible = "raspberrypi,firmware-clocks" },
 472         { },
 473 };
 474 MODULE_DEVICE_TABLE(of, raspberrypi_clk_match);
 475
 476 static struct platform_driver raspberrypi_clk_driver = {
 477         .driver = {
 478                 .name = "raspberrypi-clk",
 479                 .of_match_table = raspberrypi_clk_match,
 480         },
 481         .probe          = raspberrypi_clk_probe,
 482         .remove         = raspberrypi_clk_remove,
 483 };
 484 module_platform_driver(raspberrypi_clk_driver);
 485
 486 MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
 487 MODULE_DESCRIPTION("Raspberry Pi firmware clock driver");
 488 MODULE_LICENSE("GPL");
 489 MODULE_ALIAS("platform:raspberrypi-clk");