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_NUM_CLK_ID,
  37 };
  38
  39 static char *rpi_firmware_clk_names[] = {
  40         [RPI_FIRMWARE_EMMC_CLK_ID]      = "emmc",
  41         [RPI_FIRMWARE_UART_CLK_ID]      = "uart",
  42         [RPI_FIRMWARE_ARM_CLK_ID]       = "arm",
  43         [RPI_FIRMWARE_CORE_CLK_ID]      = "core",
  44         [RPI_FIRMWARE_V3D_CLK_ID]       = "v3d",
  45         [RPI_FIRMWARE_H264_CLK_ID]      = "h264",
  46         [RPI_FIRMWARE_ISP_CLK_ID]       = "isp",
  47         [RPI_FIRMWARE_SDRAM_CLK_ID]     = "sdram",
  48         [RPI_FIRMWARE_PIXEL_CLK_ID]     = "pixel",
  49         [RPI_FIRMWARE_PWM_CLK_ID]       = "pwm",
  50         [RPI_FIRMWARE_HEVC_CLK_ID]      = "hevc",
  51         [RPI_FIRMWARE_EMMC2_CLK_ID]     = "emmc2",
  52         [RPI_FIRMWARE_M2MC_CLK_ID]      = "m2mc",
  53         [RPI_FIRMWARE_PIXEL_BVB_CLK_ID] = "pixel-bvb",
  54 };
  55
  56 #define RPI_FIRMWARE_STATE_ENABLE_BIT   BIT(0)
  57 #define RPI_FIRMWARE_STATE_WAIT_BIT     BIT(1)
  58
  59 struct raspberrypi_clk {
  60         struct device *dev;
  61         struct rpi_firmware *firmware;
  62         struct platform_device *cpufreq;
  63 };
  64
  65 struct raspberrypi_clk_data {
  66         struct clk_hw hw;
  67
  68         unsigned int id;
  69
  70         struct raspberrypi_clk *rpi;
  71 };
  72
  73 /*
  74  * Structure of the message passed to Raspberry Pi's firmware in order to
  75  * change clock rates. The 'disable_turbo' option is only available to the ARM
  76  * clock (pllb) which we enable by default as turbo mode will alter multiple
  77  * clocks at once.
  78  *
  79  * Even though we're able to access the clock registers directly we're bound to
  80  * use the firmware interface as the firmware ultimately takes care of
  81  * mitigating overheating/undervoltage situations and we would be changing
  82  * frequencies behind his back.
  83  *
  84  * For more information on the firmware interface check:
  85  * https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface
  86  */
  87 struct raspberrypi_firmware_prop {
  88         __le32 id;
  89         __le32 val;
  90         __le32 disable_turbo;
  91 } __packed;
  92
  93 static int raspberrypi_clock_property(struct rpi_firmware *firmware,
  94                                       const struct raspberrypi_clk_data *data,
  95                                       u32 tag, u32 *val)
  96 {
  97         struct raspberrypi_firmware_prop msg = {
  98                 .id = cpu_to_le32(data->id),
  99                 .val = cpu_to_le32(*val),
 100                 .disable_turbo = cpu_to_le32(1),
 101         };
 102         int ret;
 103
 104         ret = rpi_firmware_property(firmware, tag, &msg, sizeof(msg));
 105         if (ret)
 106                 return ret;
 107
 108         *val = le32_to_cpu(msg.val);
 109
 110         return 0;
 111 }
 112
 113 static int raspberrypi_fw_is_prepared(struct clk_hw *hw)
 114 {
 115         struct raspberrypi_clk_data *data =
 116                 container_of(hw, struct raspberrypi_clk_data, hw);
 117         struct raspberrypi_clk *rpi = data->rpi;
 118         u32 val = 0;
 119         int ret;
 120
 121         ret = raspberrypi_clock_property(rpi->firmware, data,
 122                                          RPI_FIRMWARE_GET_CLOCK_STATE, &val);
 123         if (ret)
 124                 return 0;
 125
 126         return !!(val & RPI_FIRMWARE_STATE_ENABLE_BIT);
 127 }
 128
 129
 130 static unsigned long raspberrypi_fw_get_rate(struct clk_hw *hw,
 131                                              unsigned long parent_rate)
 132 {
 133         struct raspberrypi_clk_data *data =
 134                 container_of(hw, struct raspberrypi_clk_data, hw);
 135         struct raspberrypi_clk *rpi = data->rpi;
 136         u32 val = 0;
 137         int ret;
 138
 139         ret = raspberrypi_clock_property(rpi->firmware, data,
 140                                          RPI_FIRMWARE_GET_CLOCK_RATE, &val);
 141         if (ret)
 142                 return ret;
 143
 144         return val;
 145 }
 146
 147 static int raspberrypi_fw_set_rate(struct clk_hw *hw, unsigned long rate,
 148                                    unsigned long parent_rate)
 149 {
 150         struct raspberrypi_clk_data *data =
 151                 container_of(hw, struct raspberrypi_clk_data, hw);
 152         struct raspberrypi_clk *rpi = data->rpi;
 153         u32 _rate = rate;
 154         int ret;
 155
 156         ret = raspberrypi_clock_property(rpi->firmware, data,
 157                                          RPI_FIRMWARE_SET_CLOCK_RATE, &_rate);
 158         if (ret)
 159                 dev_err_ratelimited(rpi->dev, "Failed to change %s frequency: %d",
 160                                     clk_hw_get_name(hw), ret);
 161
 162         return ret;
 163 }
 164
 165 static int raspberrypi_fw_dumb_determine_rate(struct clk_hw *hw,
 166                                               struct clk_rate_request *req)
 167 {
 168         /*
 169          * The firmware will do the rounding but that isn't part of
 170          * the interface with the firmware, so we just do our best
 171          * here.
 172          */
 173         req->rate = clamp(req->rate, req->min_rate, req->max_rate);
 174         return 0;
 175 }
 176
 177 static const struct clk_ops raspberrypi_firmware_clk_ops = {
 178         .is_prepared    = raspberrypi_fw_is_prepared,
 179         .recalc_rate    = raspberrypi_fw_get_rate,
 180         .determine_rate = raspberrypi_fw_dumb_determine_rate,
 181         .set_rate       = raspberrypi_fw_set_rate,
 182 };
 183
 184 static struct clk_hw *raspberrypi_clk_register(struct raspberrypi_clk *rpi,
 185                                                unsigned int parent,
 186                                                unsigned int id)
 187 {
 188         struct raspberrypi_clk_data *data;
 189         struct clk_init_data init = {};
 190         u32 min_rate, max_rate;
 191         int ret;
 192
 193         data = devm_kzalloc(rpi->dev, sizeof(*data), GFP_KERNEL);
 194         if (!data)
 195                 return ERR_PTR(-ENOMEM);
 196         data->rpi = rpi;
 197         data->id = id;
 198
 199         init.name = devm_kasprintf(rpi->dev, GFP_KERNEL,
 200                                    "fw-clk-%s",
 201                                    rpi_firmware_clk_names[id]);
 202         init.ops = &raspberrypi_firmware_clk_ops;
 203         init.flags = CLK_GET_RATE_NOCACHE;
 204
 205         data->hw.init = &init;
 206
 207         ret = raspberrypi_clock_property(rpi->firmware, data,
 208                                          RPI_FIRMWARE_GET_MIN_CLOCK_RATE,
 209                                          &min_rate);
 210         if (ret) {
 211                 dev_err(rpi->dev, "Failed to get clock %d min freq: %d",
 212                         id, ret);
 213                 return ERR_PTR(ret);
 214         }
 215
 216         ret = raspberrypi_clock_property(rpi->firmware, data,
 217                                          RPI_FIRMWARE_GET_MAX_CLOCK_RATE,
 218                                          &max_rate);
 219         if (ret) {
 220                 dev_err(rpi->dev, "Failed to get clock %d max freq: %d\n",
 221                         id, ret);
 222                 return ERR_PTR(ret);
 223         }
 224
 225         ret = devm_clk_hw_register(rpi->dev, &data->hw);
 226         if (ret)
 227                 return ERR_PTR(ret);
 228
 229         clk_hw_set_rate_range(&data->hw, min_rate, max_rate);
 230
 231         if (id == RPI_FIRMWARE_ARM_CLK_ID) {
 232                 ret = devm_clk_hw_register_clkdev(rpi->dev, &data->hw,
 233                                                   NULL, "cpu0");
 234                 if (ret) {
 235                         dev_err(rpi->dev, "Failed to initialize clkdev\n");
 236                         return ERR_PTR(ret);
 237                 }
 238         }
 239
 240         return &data->hw;
 241 }
 242
 243 struct rpi_firmware_get_clocks_response {
 244         u32 parent;
 245         u32 id;
 246 };
 247
 248 static int raspberrypi_discover_clocks(struct raspberrypi_clk *rpi,
 249                                        struct clk_hw_onecell_data *data)
 250 {
 251         struct rpi_firmware_get_clocks_response *clks;
 252         int ret;
 253
 254         clks = devm_kcalloc(rpi->dev,
 255                             sizeof(*clks), RPI_FIRMWARE_NUM_CLK_ID,
 256                             GFP_KERNEL);
 257         if (!clks)
 258                 return -ENOMEM;
 259
 260         ret = rpi_firmware_property(rpi->firmware, RPI_FIRMWARE_GET_CLOCKS,
 261                                     clks,
 262                                     sizeof(*clks) * RPI_FIRMWARE_NUM_CLK_ID);
 263         if (ret)
 264                 return ret;
 265
 266         while (clks->id) {
 267                 struct clk_hw *hw;
 268
 269                 switch (clks->id) {
 270                 case RPI_FIRMWARE_ARM_CLK_ID:
 271                 case RPI_FIRMWARE_CORE_CLK_ID:
 272                 case RPI_FIRMWARE_M2MC_CLK_ID:
 273                 case RPI_FIRMWARE_V3D_CLK_ID:
 274                 case RPI_FIRMWARE_PIXEL_BVB_CLK_ID:
 275                         hw = raspberrypi_clk_register(rpi, clks->parent,
 276                                                       clks->id);
 277                         if (IS_ERR(hw))
 278                                 return PTR_ERR(hw);
 279
 280                         data->hws[clks->id] = hw;
 281                         data->num = clks->id + 1;
 282                         fallthrough;
 283
 284                 default:
 285                         clks++;
 286                         break;
 287                 }
 288         }
 289
 290         return 0;
 291 }
 292
 293 static int raspberrypi_clk_probe(struct platform_device *pdev)
 294 {
 295         struct clk_hw_onecell_data *clk_data;
 296         struct device_node *firmware_node;
 297         struct device *dev = &pdev->dev;
 298         struct rpi_firmware *firmware;
 299         struct raspberrypi_clk *rpi;
 300         int ret;
 301
 302         /*
 303          * We can be probed either through the an old-fashioned
 304          * platform device registration or through a DT node that is a
 305          * child of the firmware node. Handle both cases.
 306          */
 307         if (dev->of_node)
 308                 firmware_node = of_get_parent(dev->of_node);
 309         else
 310                 firmware_node = of_find_compatible_node(NULL, NULL,
 311                                                         "raspberrypi,bcm2835-firmware");
 312         if (!firmware_node) {
 313                 dev_err(dev, "Missing firmware node\n");
 314                 return -ENOENT;
 315         }
 316
 317         firmware = devm_rpi_firmware_get(&pdev->dev, firmware_node);
 318         of_node_put(firmware_node);
 319         if (!firmware)
 320                 return -EPROBE_DEFER;
 321
 322         rpi = devm_kzalloc(dev, sizeof(*rpi), GFP_KERNEL);
 323         if (!rpi)
 324                 return -ENOMEM;
 325
 326         rpi->dev = dev;
 327         rpi->firmware = firmware;
 328         platform_set_drvdata(pdev, rpi);
 329
 330         clk_data = devm_kzalloc(dev, struct_size(clk_data, hws,
 331                                                  RPI_FIRMWARE_NUM_CLK_ID),
 332                                 GFP_KERNEL);
 333         if (!clk_data)
 334                 return -ENOMEM;
 335
 336         ret = raspberrypi_discover_clocks(rpi, clk_data);
 337         if (ret)
 338                 return ret;
 339
 340         ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
 341                                           clk_data);
 342         if (ret)
 343                 return ret;
 344
 345         rpi->cpufreq = platform_device_register_data(dev, "raspberrypi-cpufreq",
 346                                                      -1, NULL, 0);
 347
 348         return 0;
 349 }
 350
 351 static int raspberrypi_clk_remove(struct platform_device *pdev)
 352 {
 353         struct raspberrypi_clk *rpi = platform_get_drvdata(pdev);
 354
 355         platform_device_unregister(rpi->cpufreq);
 356
 357         return 0;
 358 }
 359
 360 static const struct of_device_id raspberrypi_clk_match[] = {
 361         { .compatible = "raspberrypi,firmware-clocks" },
 362         { },
 363 };
 364 MODULE_DEVICE_TABLE(of, raspberrypi_clk_match);
 365
 366 static struct platform_driver raspberrypi_clk_driver = {
 367         .driver = {
 368                 .name = "raspberrypi-clk",
 369                 .of_match_table = raspberrypi_clk_match,
 370         },
 371         .probe          = raspberrypi_clk_probe,
 372         .remove         = raspberrypi_clk_remove,
 373 };
 374 module_platform_driver(raspberrypi_clk_driver);
 375
 376 MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
 377 MODULE_DESCRIPTION("Raspberry Pi firmware clock driver");
 378 MODULE_LICENSE("GPL");
 379 MODULE_ALIAS("platform:raspberrypi-clk");