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                 .minimize = true,
 134         },
 135         [RPI_FIRMWARE_HEVC_CLK_ID] = {
 136                 .export = true,
 137                 .minimize = true,
 138         },
 139         [RPI_FIRMWARE_PIXEL_BVB_CLK_ID] = {
 140                 .export = true,
 141                 .minimize = true,
 142         },
 143         [RPI_FIRMWARE_VEC_CLK_ID] = {
 144                 .export = true,
 145                 .minimize = true,
 146         },
 147         [RPI_FIRMWARE_PIXEL_CLK_ID] = {
 148                 .export = true,
 149                 .minimize = true,
 150         },
 151 };
 152
 153 /*
 154  * Structure of the message passed to Raspberry Pi's firmware in order to
 155  * change clock rates. The 'disable_turbo' option is only available to the ARM
 156  * clock (pllb) which we enable by default as turbo mode will alter multiple
 157  * clocks at once.
 158  *
 159  * Even though we're able to access the clock registers directly we're bound to
 160  * use the firmware interface as the firmware ultimately takes care of
 161  * mitigating overheating/undervoltage situations and we would be changing
 162  * frequencies behind his back.
 163  *
 164  * For more information on the firmware interface check:
 165  * https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface
 166  */
 167 struct raspberrypi_firmware_prop {
 168         __le32 id;
 169         __le32 val;
 170         __le32 disable_turbo;
 171 } __packed;
 172
 173 static int raspberrypi_clock_property(struct rpi_firmware *firmware,
 174                                       const struct raspberrypi_clk_data *data,
 175                                       u32 tag, u32 *val)
 176 {
 177         struct raspberrypi_firmware_prop msg = {
 178                 .id = cpu_to_le32(data->id),
 179                 .val = cpu_to_le32(*val),
 180                 .disable_turbo = cpu_to_le32(0),
 181         };
 182         int ret;
 183
 184         ret = rpi_firmware_property(firmware, tag, &msg, sizeof(msg));
 185         if (ret)
 186                 return ret;
 187
 188         *val = le32_to_cpu(msg.val);
 189
 190         return 0;
 191 }
 192
 193 static int raspberrypi_fw_is_prepared(struct clk_hw *hw)
 194 {
 195         struct raspberrypi_clk_data *data =
 196                 container_of(hw, struct raspberrypi_clk_data, hw);
 197         struct raspberrypi_clk *rpi = data->rpi;
 198         u32 val = 0;
 199         int ret;
 200
 201         ret = raspberrypi_clock_property(rpi->firmware, data,
 202                                          RPI_FIRMWARE_GET_CLOCK_STATE, &val);
 203         if (ret)
 204                 return 0;
 205
 206         return !!(val & RPI_FIRMWARE_STATE_ENABLE_BIT);
 207 }
 208
 209
 210 static unsigned long raspberrypi_fw_get_rate(struct clk_hw *hw,
 211                                              unsigned long parent_rate)
 212 {
 213         struct raspberrypi_clk_data *data =
 214                 container_of(hw, struct raspberrypi_clk_data, hw);
 215         struct raspberrypi_clk *rpi = data->rpi;
 216         u32 val = 0;
 217         int ret;
 218
 219         ret = raspberrypi_clock_property(rpi->firmware, data,
 220                                          RPI_FIRMWARE_GET_CLOCK_RATE, &val);
 221         if (ret)
 222                 return ret;
 223
 224         return val;
 225 }
 226
 227 static int raspberrypi_fw_set_rate(struct clk_hw *hw, unsigned long rate,
 228                                    unsigned long parent_rate)
 229 {
 230         struct raspberrypi_clk_data *data =
 231                 container_of(hw, struct raspberrypi_clk_data, hw);
 232         struct raspberrypi_clk *rpi = data->rpi;
 233         u32 _rate = rate;
 234         int ret;
 235
 236         ret = raspberrypi_clock_property(rpi->firmware, data,
 237                                          RPI_FIRMWARE_SET_CLOCK_RATE, &_rate);
 238         if (ret)
 239                 dev_err_ratelimited(rpi->dev, "Failed to change %s frequency: %d",
 240                                     clk_hw_get_name(hw), ret);
 241
 242         return ret;
 243 }
 244
 245 static int raspberrypi_fw_dumb_determine_rate(struct clk_hw *hw,
 246                                               struct clk_rate_request *req)
 247 {
 248         struct raspberrypi_clk_data *data =
 249                 container_of(hw, struct raspberrypi_clk_data, hw);
 250         struct raspberrypi_clk_variant *variant = data->variant;
 251
 252         /*
 253          * The firmware will do the rounding but that isn't part of
 254          * the interface with the firmware, so we just do our best
 255          * here.
 256          */
 257
 258         req->rate = clamp(req->rate, req->min_rate, req->max_rate);
 259
 260         /*
 261          * We want to aggressively reduce the clock rate here, so let's
 262          * just ignore the requested rate and return the bare minimum
 263          * rate we can get away with.
 264          */
 265         if (variant->minimize && req->min_rate > 0)
 266                 req->rate = req->min_rate;
 267
 268         return 0;
 269 }
 270
 271 static const struct clk_ops raspberrypi_firmware_clk_ops = {
 272         .is_prepared    = raspberrypi_fw_is_prepared,
 273         .recalc_rate    = raspberrypi_fw_get_rate,
 274         .determine_rate = raspberrypi_fw_dumb_determine_rate,
 275         .set_rate       = raspberrypi_fw_set_rate,
 276 };
 277
 278 static struct clk_hw *raspberrypi_clk_register(struct raspberrypi_clk *rpi,
 279                                                unsigned int parent,
 280                                                unsigned int id,
 281                                                struct raspberrypi_clk_variant *variant)
 282 {
 283         struct raspberrypi_clk_data *data;
 284         struct clk_init_data init = {};
 285         u32 min_rate, max_rate;
 286         int ret;
 287
 288         data = devm_kzalloc(rpi->dev, sizeof(*data), GFP_KERNEL);
 289         if (!data)
 290                 return ERR_PTR(-ENOMEM);
 291         data->rpi = rpi;
 292         data->id = id;
 293         data->variant = variant;
 294
 295         init.name = devm_kasprintf(rpi->dev, GFP_KERNEL,
 296                                    "fw-clk-%s",
 297                                    rpi_firmware_clk_names[id]);
 298         init.ops = &raspberrypi_firmware_clk_ops;
 299         init.flags = CLK_GET_RATE_NOCACHE;
 300
 301         data->hw.init = &init;
 302
 303         ret = raspberrypi_clock_property(rpi->firmware, data,
 304                                          RPI_FIRMWARE_GET_MIN_CLOCK_RATE,
 305                                          &min_rate);
 306         if (ret) {
 307                 dev_err(rpi->dev, "Failed to get clock %d min freq: %d",
 308                         id, ret);
 309                 return ERR_PTR(ret);
 310         }
 311
 312         ret = raspberrypi_clock_property(rpi->firmware, data,
 313                                          RPI_FIRMWARE_GET_MAX_CLOCK_RATE,
 314                                          &max_rate);
 315         if (ret) {
 316                 dev_err(rpi->dev, "Failed to get clock %d max freq: %d\n",
 317                         id, ret);
 318                 return ERR_PTR(ret);
 319         }
 320
 321         ret = devm_clk_hw_register(rpi->dev, &data->hw);
 322         if (ret)
 323                 return ERR_PTR(ret);
 324
 325         clk_hw_set_rate_range(&data->hw, min_rate, max_rate);
 326
 327         if (variant->clkdev) {
 328                 ret = devm_clk_hw_register_clkdev(rpi->dev, &data->hw,
 329                                                   NULL, variant->clkdev);
 330                 if (ret) {
 331                         dev_err(rpi->dev, "Failed to initialize clkdev\n");
 332                         return ERR_PTR(ret);
 333                 }
 334         }
 335
 336         if (variant->min_rate) {
 337                 unsigned long rate;
 338
 339                 clk_hw_set_rate_range(&data->hw, variant->min_rate, max_rate);
 340
 341                 rate = raspberrypi_fw_get_rate(&data->hw, 0);
 342                 if (rate < variant->min_rate) {
 343                         ret = raspberrypi_fw_set_rate(&data->hw, variant->min_rate, 0);
 344                         if (ret)
 345                                 return ERR_PTR(ret);
 346                 }
 347         }
 348
 349         return &data->hw;
 350 }
 351
 352 struct rpi_firmware_get_clocks_response {
 353         u32 parent;
 354         u32 id;
 355 };
 356
 357 static int raspberrypi_discover_clocks(struct raspberrypi_clk *rpi,
 358                                        struct clk_hw_onecell_data *data)
 359 {
 360         struct rpi_firmware_get_clocks_response *clks;
 361         int ret;
 362
 363         clks = devm_kcalloc(rpi->dev,
 364                             sizeof(*clks), RPI_FIRMWARE_NUM_CLK_ID,
 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", clks->id);
 380                         return -EINVAL;
 381                 }
 382
 383                 variant = &raspberrypi_clk_variants[clks->id];
 384                 if (variant->export) {
 385                         struct clk_hw *hw;
 386
 387                         hw = raspberrypi_clk_register(rpi, clks->parent,
 388                                                       clks->id, variant);
 389                         if (IS_ERR(hw))
 390                                 return PTR_ERR(hw);
 391
 392                         data->hws[clks->id] = hw;
 393                         data->num = clks->id + 1;
 394                 }
 395
 396                 clks++;
 397         }
 398
 399         return 0;
 400 }
 401
 402 static int raspberrypi_clk_probe(struct platform_device *pdev)
 403 {
 404         struct clk_hw_onecell_data *clk_data;
 405         struct device_node *firmware_node;
 406         struct device *dev = &pdev->dev;
 407         struct rpi_firmware *firmware;
 408         struct raspberrypi_clk *rpi;
 409         int ret;
 410
 411         /*
 412          * We can be probed either through the an old-fashioned
 413          * platform device registration or through a DT node that is a
 414          * child of the firmware node. Handle both cases.
 415          */
 416         if (dev->of_node)
 417                 firmware_node = of_get_parent(dev->of_node);
 418         else
 419                 firmware_node = of_find_compatible_node(NULL, NULL,
 420                                                         "raspberrypi,bcm2835-firmware");
 421         if (!firmware_node) {
 422                 dev_err(dev, "Missing firmware node\n");
 423                 return -ENOENT;
 424         }
 425
 426         firmware = devm_rpi_firmware_get(&pdev->dev, firmware_node);
 427         of_node_put(firmware_node);
 428         if (!firmware)
 429                 return -EPROBE_DEFER;
 430
 431         rpi = devm_kzalloc(dev, sizeof(*rpi), GFP_KERNEL);
 432         if (!rpi)
 433                 return -ENOMEM;
 434
 435         rpi->dev = dev;
 436         rpi->firmware = firmware;
 437         platform_set_drvdata(pdev, rpi);
 438
 439         clk_data = devm_kzalloc(dev, struct_size(clk_data, hws,
 440                                                  RPI_FIRMWARE_NUM_CLK_ID),
 441                                 GFP_KERNEL);
 442         if (!clk_data)
 443                 return -ENOMEM;
 444
 445         ret = raspberrypi_discover_clocks(rpi, clk_data);
 446         if (ret)
 447                 return ret;
 448
 449         ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
 450                                           clk_data);
 451         if (ret)
 452                 return ret;
 453
 454         rpi->cpufreq = platform_device_register_data(dev, "raspberrypi-cpufreq",
 455                                                      -1, NULL, 0);
 456
 457         return 0;
 458 }
 459
 460 static int raspberrypi_clk_remove(struct platform_device *pdev)
 461 {
 462         struct raspberrypi_clk *rpi = platform_get_drvdata(pdev);
 463
 464         platform_device_unregister(rpi->cpufreq);
 465
 466         return 0;
 467 }
 468
 469 static const struct of_device_id raspberrypi_clk_match[] = {
 470         { .compatible = "raspberrypi,firmware-clocks" },
 471         { },
 472 };
 473 MODULE_DEVICE_TABLE(of, raspberrypi_clk_match);
 474
 475 static struct platform_driver raspberrypi_clk_driver = {
 476         .driver = {
 477                 .name = "raspberrypi-clk",
 478                 .of_match_table = raspberrypi_clk_match,
 479         },
 480         .probe          = raspberrypi_clk_probe,
 481         .remove         = raspberrypi_clk_remove,
 482 };
 483 module_platform_driver(raspberrypi_clk_driver);
 484
 485 MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
 486 MODULE_DESCRIPTION("Raspberry Pi firmware clock driver");
 487 MODULE_LICENSE("GPL");
 488 MODULE_ALIAS("platform:raspberrypi-clk");