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