git.librecmc.org Git - oweals/openwrt.git/blob

   1 From 35306211392a8c17ba6cde2a6b5d1beb61ca7d54 Mon Sep 17 00:00:00 2001
   2 From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
   3 Date: Wed, 12 Jun 2019 20:24:54 +0200
   4 Subject: [PATCH] clk: bcm283x: add driver interfacing with Raspberry
   5  Pi's firmware
   6
   7 Commit 4e85e535e6cc6e8a96350e8ee684d0f22eb8629e upstream.
   8
   9 Raspberry Pi's firmware offers an interface though which update it's
  10 clock's frequencies. This is specially useful in order to change the CPU
  11 clock (pllb_arm) which is 'owned' by the firmware and we're unable to
  12 scale using the register interface provided by clk-bcm2835.
  13
  14 Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
  15 Acked-by: Eric Anholt <eric@anholt.net>
  16 Signed-off-by: Stephen Boyd <sboyd@kernel.org>
  17 ---
  18  drivers/clk/bcm/Kconfig           |   7 +
  19  drivers/clk/bcm/Makefile          |   1 +
  20  drivers/clk/bcm/clk-raspberrypi.c | 300 ++++++++++++++++++++++++++++++
  21  3 files changed, 308 insertions(+)
  22  create mode 100644 drivers/clk/bcm/clk-raspberrypi.c
  23
  24 --- a/drivers/clk/bcm/Kconfig
  25 +++ b/drivers/clk/bcm/Kconfig
  26 @@ -63,3 +63,10 @@ config CLK_BCM_SR
  27         default ARCH_BCM_IPROC
  28         help
  29           Enable common clock framework support for the Broadcom Stingray SoC
  30 +
  31 +config CLK_RASPBERRYPI
  32 +       tristate "Raspberry Pi firmware based clock support"
  33 +       depends on RASPBERRYPI_FIRMWARE || (COMPILE_TEST && !RASPBERRYPI_FIRMWARE)
  34 +       help
  35 +         Enable common clock framework support for Raspberry Pi's firmware
  36 +         dependent clocks
  37 --- a/drivers/clk/bcm/Makefile
  38 +++ b/drivers/clk/bcm/Makefile
  39 @@ -7,6 +7,7 @@ obj-$(CONFIG_CLK_BCM_KONA)      += clk-bcm216
  40  obj-$(CONFIG_COMMON_CLK_IPROC) += clk-iproc-armpll.o clk-iproc-pll.o clk-iproc-asiu.o
  41  obj-$(CONFIG_ARCH_BCM2835)     += clk-bcm2835.o
  42  obj-$(CONFIG_ARCH_BCM2835)     += clk-bcm2835-aux.o
  43 +obj-$(CONFIG_CLK_RASPBERRYPI)  += clk-raspberrypi.o
  44  obj-$(CONFIG_ARCH_BCM_53573)   += clk-bcm53573-ilp.o
  45  obj-$(CONFIG_CLK_BCM_CYGNUS)   += clk-cygnus.o
  46  obj-$(CONFIG_CLK_BCM_HR2)      += clk-hr2.o
  47 --- /dev/null
  48 +++ b/drivers/clk/bcm/clk-raspberrypi.c
  49 @@ -0,0 +1,300 @@
  50 +// SPDX-License-Identifier: GPL-2.0+
  51 +/*
  52 + * Raspberry Pi driver for firmware controlled clocks
  53 + *
  54 + * Even though clk-bcm2835 provides an interface to the hardware registers for
  55 + * the system clocks we've had to factor out 'pllb' as the firmware 'owns' it.
  56 + * We're not allowed to change it directly as we might race with the
  57 + * over-temperature and under-voltage protections provided by the firmware.
  58 + *
  59 + * Copyright (C) 2019 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
  60 + */
  61 +
  62 +#include <linux/clkdev.h>
  63 +#include <linux/clk-provider.h>
  64 +#include <linux/io.h>
  65 +#include <linux/module.h>
  66 +#include <linux/platform_device.h>
  67 +
  68 +#include <soc/bcm2835/raspberrypi-firmware.h>
  69 +
  70 +#define RPI_FIRMWARE_ARM_CLK_ID                0x00000003
  71 +
  72 +#define RPI_FIRMWARE_STATE_ENABLE_BIT  BIT(0)
  73 +#define RPI_FIRMWARE_STATE_WAIT_BIT    BIT(1)
  74 +
  75 +/*
  76 + * Even though the firmware interface alters 'pllb' the frequencies are
  77 + * provided as per 'pllb_arm'. We need to scale before passing them trough.
  78 + */
  79 +#define RPI_FIRMWARE_PLLB_ARM_DIV_RATE 2
  80 +
  81 +#define A2W_PLL_FRAC_BITS              20
  82 +
  83 +struct raspberrypi_clk {
  84 +       struct device *dev;
  85 +       struct rpi_firmware *firmware;
  86 +
  87 +       unsigned long min_rate;
  88 +       unsigned long max_rate;
  89 +
  90 +       struct clk_hw pllb;
  91 +       struct clk_hw *pllb_arm;
  92 +       struct clk_lookup *pllb_arm_lookup;
  93 +};
  94 +
  95 +/*
  96 + * Structure of the message passed to Raspberry Pi's firmware in order to
  97 + * change clock rates. The 'disable_turbo' option is only available to the ARM
  98 + * clock (pllb) which we enable by default as turbo mode will alter multiple
  99 + * clocks at once.
 100 + *
 101 + * Even though we're able to access the clock registers directly we're bound to
 102 + * use the firmware interface as the firmware ultimately takes care of
 103 + * mitigating overheating/undervoltage situations and we would be changing
 104 + * frequencies behind his back.
 105 + *
 106 + * For more information on the firmware interface check:
 107 + * https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface
 108 + */
 109 +struct raspberrypi_firmware_prop {
 110 +       __le32 id;
 111 +       __le32 val;
 112 +       __le32 disable_turbo;
 113 +} __packed;
 114 +
 115 +static int raspberrypi_clock_property(struct rpi_firmware *firmware, u32 tag,
 116 +                                     u32 clk, u32 *val)
 117 +{
 118 +       struct raspberrypi_firmware_prop msg = {
 119 +               .id = cpu_to_le32(clk),
 120 +               .val = cpu_to_le32(*val),
 121 +               .disable_turbo = cpu_to_le32(1),
 122 +       };
 123 +       int ret;
 124 +
 125 +       ret = rpi_firmware_property(firmware, tag, &msg, sizeof(msg));
 126 +       if (ret)
 127 +               return ret;
 128 +
 129 +       *val = le32_to_cpu(msg.val);
 130 +
 131 +       return 0;
 132 +}
 133 +
 134 +static int raspberrypi_fw_pll_is_on(struct clk_hw *hw)
 135 +{
 136 +       struct raspberrypi_clk *rpi = container_of(hw, struct raspberrypi_clk,
 137 +                                                  pllb);
 138 +       u32 val = 0;
 139 +       int ret;
 140 +
 141 +       ret = raspberrypi_clock_property(rpi->firmware,
 142 +                                        RPI_FIRMWARE_GET_CLOCK_STATE,
 143 +                                        RPI_FIRMWARE_ARM_CLK_ID, &val);
 144 +       if (ret)
 145 +               return 0;
 146 +
 147 +       return !!(val & RPI_FIRMWARE_STATE_ENABLE_BIT);
 148 +}
 149 +
 150 +
 151 +static unsigned long raspberrypi_fw_pll_get_rate(struct clk_hw *hw,
 152 +                                                unsigned long parent_rate)
 153 +{
 154 +       struct raspberrypi_clk *rpi = container_of(hw, struct raspberrypi_clk,
 155 +                                                  pllb);
 156 +       u32 val = 0;
 157 +       int ret;
 158 +
 159 +       ret = raspberrypi_clock_property(rpi->firmware,
 160 +                                        RPI_FIRMWARE_GET_CLOCK_RATE,
 161 +                                        RPI_FIRMWARE_ARM_CLK_ID,
 162 +                                        &val);
 163 +       if (ret)
 164 +               return ret;
 165 +
 166 +       return val * RPI_FIRMWARE_PLLB_ARM_DIV_RATE;
 167 +}
 168 +
 169 +static int raspberrypi_fw_pll_set_rate(struct clk_hw *hw, unsigned long rate,
 170 +                                      unsigned long parent_rate)
 171 +{
 172 +       struct raspberrypi_clk *rpi = container_of(hw, struct raspberrypi_clk,
 173 +                                                  pllb);
 174 +       u32 new_rate = rate / RPI_FIRMWARE_PLLB_ARM_DIV_RATE;
 175 +       int ret;
 176 +
 177 +       ret = raspberrypi_clock_property(rpi->firmware,
 178 +                                        RPI_FIRMWARE_SET_CLOCK_RATE,
 179 +                                        RPI_FIRMWARE_ARM_CLK_ID,
 180 +                                        &new_rate);
 181 +       if (ret)
 182 +               dev_err_ratelimited(rpi->dev, "Failed to change %s frequency: %d",
 183 +                                   clk_hw_get_name(hw), ret);
 184 +
 185 +       return ret;
 186 +}
 187 +
 188 +/*
 189 + * Sadly there is no firmware rate rounding interface. We borrowed it from
 190 + * clk-bcm2835.
 191 + */
 192 +static int raspberrypi_pll_determine_rate(struct clk_hw *hw,
 193 +                                         struct clk_rate_request *req)
 194 +{
 195 +       struct raspberrypi_clk *rpi = container_of(hw, struct raspberrypi_clk,
 196 +                                                  pllb);
 197 +       u64 div, final_rate;
 198 +       u32 ndiv, fdiv;
 199 +
 200 +       /* We can't use req->rate directly as it would overflow */
 201 +       final_rate = clamp(req->rate, rpi->min_rate, rpi->max_rate);
 202 +
 203 +       div = (u64)final_rate << A2W_PLL_FRAC_BITS;
 204 +       do_div(div, req->best_parent_rate);
 205 +
 206 +       ndiv = div >> A2W_PLL_FRAC_BITS;
 207 +       fdiv = div & ((1 << A2W_PLL_FRAC_BITS) - 1);
 208 +
 209 +       final_rate = ((u64)req->best_parent_rate *
 210 +                                       ((ndiv << A2W_PLL_FRAC_BITS) + fdiv));
 211 +
 212 +       req->rate = final_rate >> A2W_PLL_FRAC_BITS;
 213 +
 214 +       return 0;
 215 +}
 216 +
 217 +static const struct clk_ops raspberrypi_firmware_pll_clk_ops = {
 218 +       .is_prepared = raspberrypi_fw_pll_is_on,
 219 +       .recalc_rate = raspberrypi_fw_pll_get_rate,
 220 +       .set_rate = raspberrypi_fw_pll_set_rate,
 221 +       .determine_rate = raspberrypi_pll_determine_rate,
 222 +};
 223 +
 224 +static int raspberrypi_register_pllb(struct raspberrypi_clk *rpi)
 225 +{
 226 +       u32 min_rate = 0, max_rate = 0;
 227 +       struct clk_init_data init;
 228 +       int ret;
 229 +
 230 +       memset(&init, 0, sizeof(init));
 231 +
 232 +       /* All of the PLLs derive from the external oscillator. */
 233 +       init.parent_names = (const char *[]){ "osc" };
 234 +       init.num_parents = 1;
 235 +       init.name = "pllb";
 236 +       init.ops = &raspberrypi_firmware_pll_clk_ops;
 237 +       init.flags = CLK_GET_RATE_NOCACHE | CLK_IGNORE_UNUSED;
 238 +
 239 +       /* Get min & max rates set by the firmware */
 240 +       ret = raspberrypi_clock_property(rpi->firmware,
 241 +                                        RPI_FIRMWARE_GET_MIN_CLOCK_RATE,
 242 +                                        RPI_FIRMWARE_ARM_CLK_ID,
 243 +                                        &min_rate);
 244 +       if (ret) {
 245 +               dev_err(rpi->dev, "Failed to get %s min freq: %d\n",
 246 +                       init.name, ret);
 247 +               return ret;
 248 +       }
 249 +
 250 +       ret = raspberrypi_clock_property(rpi->firmware,
 251 +                                        RPI_FIRMWARE_GET_MAX_CLOCK_RATE,
 252 +                                        RPI_FIRMWARE_ARM_CLK_ID,
 253 +                                        &max_rate);
 254 +       if (ret) {
 255 +               dev_err(rpi->dev, "Failed to get %s max freq: %d\n",
 256 +                       init.name, ret);
 257 +               return ret;
 258 +       }
 259 +
 260 +       if (!min_rate || !max_rate) {
 261 +               dev_err(rpi->dev, "Unexpected frequency range: min %u, max %u\n",
 262 +                       min_rate, max_rate);
 263 +               return -EINVAL;
 264 +       }
 265 +
 266 +       dev_info(rpi->dev, "CPU frequency range: min %u, max %u\n",
 267 +                min_rate, max_rate);
 268 +
 269 +       rpi->min_rate = min_rate * RPI_FIRMWARE_PLLB_ARM_DIV_RATE;
 270 +       rpi->max_rate = max_rate * RPI_FIRMWARE_PLLB_ARM_DIV_RATE;
 271 +
 272 +       rpi->pllb.init = &init;
 273 +
 274 +       return devm_clk_hw_register(rpi->dev, &rpi->pllb);
 275 +}
 276 +
 277 +static int raspberrypi_register_pllb_arm(struct raspberrypi_clk *rpi)
 278 +{
 279 +       rpi->pllb_arm = clk_hw_register_fixed_factor(rpi->dev,
 280 +                               "pllb_arm", "pllb",
 281 +                               CLK_SET_RATE_PARENT | CLK_GET_RATE_NOCACHE,
 282 +                               1, 2);
 283 +       if (IS_ERR(rpi->pllb_arm)) {
 284 +               dev_err(rpi->dev, "Failed to initialize pllb_arm\n");
 285 +               return PTR_ERR(rpi->pllb_arm);
 286 +       }
 287 +
 288 +       rpi->pllb_arm_lookup = clkdev_hw_create(rpi->pllb_arm, NULL, "cpu0");
 289 +       if (!rpi->pllb_arm_lookup) {
 290 +               dev_err(rpi->dev, "Failed to initialize pllb_arm_lookup\n");
 291 +               clk_hw_unregister_fixed_factor(rpi->pllb_arm);
 292 +               return -ENOMEM;
 293 +       }
 294 +
 295 +       return 0;
 296 +}
 297 +
 298 +static int raspberrypi_clk_probe(struct platform_device *pdev)
 299 +{
 300 +       struct device_node *firmware_node;
 301 +       struct device *dev = &pdev->dev;
 302 +       struct rpi_firmware *firmware;
 303 +       struct raspberrypi_clk *rpi;
 304 +       int ret;
 305 +
 306 +       firmware_node = of_find_compatible_node(NULL, NULL,
 307 +                                       "raspberrypi,bcm2835-firmware");
 308 +       if (!firmware_node) {
 309 +               dev_err(dev, "Missing firmware node\n");
 310 +               return -ENOENT;
 311 +       }
 312 +
 313 +       firmware = rpi_firmware_get(firmware_node);
 314 +       of_node_put(firmware_node);
 315 +       if (!firmware)
 316 +               return -EPROBE_DEFER;
 317 +
 318 +       rpi = devm_kzalloc(dev, sizeof(*rpi), GFP_KERNEL);
 319 +       if (!rpi)
 320 +               return -ENOMEM;
 321 +
 322 +       rpi->dev = dev;
 323 +       rpi->firmware = firmware;
 324 +
 325 +       ret = raspberrypi_register_pllb(rpi);
 326 +       if (ret) {
 327 +               dev_err(dev, "Failed to initialize pllb, %d\n", ret);
 328 +               return ret;
 329 +       }
 330 +
 331 +       ret = raspberrypi_register_pllb_arm(rpi);
 332 +       if (ret)
 333 +               return ret;
 334 +
 335 +       return 0;
 336 +}
 337 +
 338 +static struct platform_driver raspberrypi_clk_driver = {
 339 +       .driver = {
 340 +               .name = "raspberrypi-clk",
 341 +       },
 342 +       .probe          = raspberrypi_clk_probe,
 343 +};
 344 +module_platform_driver(raspberrypi_clk_driver);
 345 +
 346 +MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
 347 +MODULE_DESCRIPTION("Raspberry Pi firmware clock driver");
 348 +MODULE_LICENSE("GPL");
 349 +MODULE_ALIAS("platform:raspberrypi-clk");