1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (c) 2015 Endless Mobile, Inc. 4 * Author: Carlo Caione <carlo@endlessm.com> 5 * 6 * Copyright (c) 2018 Baylibre, SAS. 7 * Author: Jerome Brunet <jbrunet@baylibre.com> 8 */ 9 10 /* 11 * In the most basic form, a Meson PLL is composed as follows: 12 * 13 * PLL 14 * +--------------------------------+ 15 * | | 16 * | +--+ | 17 * in >>-----[ /N ]--->| | +-----+ | 18 * | | |------| DCO |---->> out 19 * | +--------->| | +--v--+ | 20 * | | +--+ | | 21 * | | | | 22 * | +--[ *(M + (F/Fmax) ]<--+ | 23 * | | 24 * +--------------------------------+ 25 * 26 * out = in * (m + frac / frac_max) / n 27 */ 28 29 #include <linux/clk-provider.h> 30 #include <linux/delay.h> 31 #include <linux/err.h> 32 #include <linux/io.h> 33 #include <linux/math64.h> 34 #include <linux/module.h> 35 36 #include "clk-regmap.h" 37 #include "clk-pll.h" 38 39 static inline struct meson_clk_pll_data * 40 meson_clk_pll_data(struct clk_regmap *clk) 41 { 42 return (struct meson_clk_pll_data *)clk->data; 43 } 44 45 static int __pll_round_closest_mult(struct meson_clk_pll_data *pll) 46 { 47 if ((pll->flags & CLK_MESON_PLL_ROUND_CLOSEST) && 48 !MESON_PARM_APPLICABLE(&pll->frac)) 49 return 1; 50 51 return 0; 52 } 53 54 static unsigned long __pll_params_to_rate(unsigned long parent_rate, 55 unsigned int m, unsigned int n, 56 unsigned int frac, 57 struct meson_clk_pll_data *pll) 58 { 59 u64 rate = (u64)parent_rate * m; 60 61 if (frac && MESON_PARM_APPLICABLE(&pll->frac)) { 62 u64 frac_rate = (u64)parent_rate * frac; 63 64 rate += DIV_ROUND_UP_ULL(frac_rate, 65 (1 << pll->frac.width)); 66 } 67 68 return DIV_ROUND_UP_ULL(rate, n); 69 } 70 71 static unsigned long meson_clk_pll_recalc_rate(struct clk_hw *hw, 72 unsigned long parent_rate) 73 { 74 struct clk_regmap *clk = to_clk_regmap(hw); 75 struct meson_clk_pll_data *pll = meson_clk_pll_data(clk); 76 unsigned int m, n, frac; 77 78 n = meson_parm_read(clk->map, &pll->n); 79 80 /* 81 * On some HW, N is set to zero on init. This value is invalid as 82 * it would result in a division by zero. The rate can't be 83 * calculated in this case 84 */ 85 if (n == 0) 86 return 0; 87 88 m = meson_parm_read(clk->map, &pll->m); 89 90 frac = MESON_PARM_APPLICABLE(&pll->frac) ? 91 meson_parm_read(clk->map, &pll->frac) : 92 0; 93 94 return __pll_params_to_rate(parent_rate, m, n, frac, pll); 95 } 96 97 static unsigned int __pll_params_with_frac(unsigned long rate, 98 unsigned long parent_rate, 99 unsigned int m, 100 unsigned int n, 101 struct meson_clk_pll_data *pll) 102 { 103 unsigned int frac_max = (1 << pll->frac.width); 104 u64 val = (u64)rate * n; 105 106 /* Bail out if we are already over the requested rate */ 107 if (rate < parent_rate * m / n) 108 return 0; 109 110 if (pll->flags & CLK_MESON_PLL_ROUND_CLOSEST) 111 val = DIV_ROUND_CLOSEST_ULL(val * frac_max, parent_rate); 112 else 113 val = div_u64(val * frac_max, parent_rate); 114 115 val -= m * frac_max; 116 117 return min((unsigned int)val, (frac_max - 1)); 118 } 119 120 static bool meson_clk_pll_is_better(unsigned long rate, 121 unsigned long best, 122 unsigned long now, 123 struct meson_clk_pll_data *pll) 124 { 125 if (__pll_round_closest_mult(pll)) { 126 /* Round Closest */ 127 if (abs(now - rate) < abs(best - rate)) 128 return true; 129 } else { 130 /* Round down */ 131 if (now <= rate && best < now) 132 return true; 133 } 134 135 return false; 136 } 137 138 static int meson_clk_get_pll_table_index(unsigned int index, 139 unsigned int *m, 140 unsigned int *n, 141 struct meson_clk_pll_data *pll) 142 { 143 if (!pll->table[index].n) 144 return -EINVAL; 145 146 *m = pll->table[index].m; 147 *n = pll->table[index].n; 148 149 return 0; 150 } 151 152 static unsigned int meson_clk_get_pll_range_m(unsigned long rate, 153 unsigned long parent_rate, 154 unsigned int n, 155 struct meson_clk_pll_data *pll) 156 { 157 u64 val = (u64)rate * n; 158 159 if (__pll_round_closest_mult(pll)) 160 return DIV_ROUND_CLOSEST_ULL(val, parent_rate); 161 162 return div_u64(val, parent_rate); 163 } 164 165 static int meson_clk_get_pll_range_index(unsigned long rate, 166 unsigned long parent_rate, 167 unsigned int index, 168 unsigned int *m, 169 unsigned int *n, 170 struct meson_clk_pll_data *pll) 171 { 172 *n = index + 1; 173 174 /* Check the predivider range */ 175 if (*n >= (1 << pll->n.width)) 176 return -EINVAL; 177 178 if (*n == 1) { 179 /* Get the boundaries out the way */ 180 if (rate <= pll->range->min * parent_rate) { 181 *m = pll->range->min; 182 return -ENODATA; 183 } else if (rate >= pll->range->max * parent_rate) { 184 *m = pll->range->max; 185 return -ENODATA; 186 } 187 } 188 189 *m = meson_clk_get_pll_range_m(rate, parent_rate, *n, pll); 190 191 /* the pre-divider gives a multiplier too big - stop */ 192 if (*m >= (1 << pll->m.width)) 193 return -EINVAL; 194 195 return 0; 196 } 197 198 static int meson_clk_get_pll_get_index(unsigned long rate, 199 unsigned long parent_rate, 200 unsigned int index, 201 unsigned int *m, 202 unsigned int *n, 203 struct meson_clk_pll_data *pll) 204 { 205 if (pll->range) 206 return meson_clk_get_pll_range_index(rate, parent_rate, 207 index, m, n, pll); 208 else if (pll->table) 209 return meson_clk_get_pll_table_index(index, m, n, pll); 210 211 return -EINVAL; 212 } 213 214 static int meson_clk_get_pll_settings(unsigned long rate, 215 unsigned long parent_rate, 216 unsigned int *best_m, 217 unsigned int *best_n, 218 struct meson_clk_pll_data *pll) 219 { 220 unsigned long best = 0, now = 0; 221 unsigned int i, m, n; 222 int ret; 223 224 for (i = 0, ret = 0; !ret; i++) { 225 ret = meson_clk_get_pll_get_index(rate, parent_rate, 226 i, &m, &n, pll); 227 if (ret == -EINVAL) 228 break; 229 230 now = __pll_params_to_rate(parent_rate, m, n, 0, pll); 231 if (meson_clk_pll_is_better(rate, best, now, pll)) { 232 best = now; 233 *best_m = m; 234 *best_n = n; 235 236 if (now == rate) 237 break; 238 } 239 } 240 241 return best ? 0 : -EINVAL; 242 } 243 244 static int meson_clk_pll_determine_rate(struct clk_hw *hw, 245 struct clk_rate_request *req) 246 { 247 struct clk_regmap *clk = to_clk_regmap(hw); 248 struct meson_clk_pll_data *pll = meson_clk_pll_data(clk); 249 unsigned int m, n, frac; 250 unsigned long round; 251 int ret; 252 253 ret = meson_clk_get_pll_settings(req->rate, req->best_parent_rate, 254 &m, &n, pll); 255 if (ret) 256 return ret; 257 258 round = __pll_params_to_rate(req->best_parent_rate, m, n, 0, pll); 259 260 if (!MESON_PARM_APPLICABLE(&pll->frac) || req->rate == round) { 261 req->rate = round; 262 return 0; 263 } 264 265 /* 266 * The rate provided by the setting is not an exact match, let's 267 * try to improve the result using the fractional parameter 268 */ 269 frac = __pll_params_with_frac(req->rate, req->best_parent_rate, m, n, pll); 270 req->rate = __pll_params_to_rate(req->best_parent_rate, m, n, frac, pll); 271 272 return 0; 273 } 274 275 static int meson_clk_pll_wait_lock(struct clk_hw *hw) 276 { 277 struct clk_regmap *clk = to_clk_regmap(hw); 278 struct meson_clk_pll_data *pll = meson_clk_pll_data(clk); 279 int delay = 5000; 280 281 do { 282 /* Is the clock locked now ? Time out after 100ms. */ 283 if (meson_parm_read(clk->map, &pll->l)) 284 return 0; 285 286 udelay(20); 287 } while (--delay); 288 289 return -ETIMEDOUT; 290 } 291 292 static int meson_clk_pll_init(struct clk_hw *hw) 293 { 294 struct clk_regmap *clk = to_clk_regmap(hw); 295 struct meson_clk_pll_data *pll = meson_clk_pll_data(clk); 296 297 if (pll->init_count) { 298 meson_parm_write(clk->map, &pll->rst, 1); 299 regmap_multi_reg_write(clk->map, pll->init_regs, 300 pll->init_count); 301 meson_parm_write(clk->map, &pll->rst, 0); 302 } 303 304 return 0; 305 } 306 307 static int meson_clk_pll_is_enabled(struct clk_hw *hw) 308 { 309 struct clk_regmap *clk = to_clk_regmap(hw); 310 struct meson_clk_pll_data *pll = meson_clk_pll_data(clk); 311 312 if (meson_parm_read(clk->map, &pll->rst) || 313 !meson_parm_read(clk->map, &pll->en) || 314 !meson_parm_read(clk->map, &pll->l)) 315 return 0; 316 317 return 1; 318 } 319 320 static int meson_clk_pcie_pll_enable(struct clk_hw *hw) 321 { 322 int retries = 10; 323 324 do { 325 meson_clk_pll_init(hw); 326 if (!meson_clk_pll_wait_lock(hw)) 327 return 0; 328 pr_info("Retry enabling PCIe PLL clock\n"); 329 } while (--retries); 330 331 return -EIO; 332 } 333 334 static int meson_clk_pll_enable(struct clk_hw *hw) 335 { 336 struct clk_regmap *clk = to_clk_regmap(hw); 337 struct meson_clk_pll_data *pll = meson_clk_pll_data(clk); 338 339 /* do nothing if the PLL is already enabled */ 340 if (clk_hw_is_enabled(hw)) 341 return 0; 342 343 /* Make sure the pll is in reset */ 344 meson_parm_write(clk->map, &pll->rst, 1); 345 346 /* Enable the pll */ 347 meson_parm_write(clk->map, &pll->en, 1); 348 349 /* Take the pll out reset */ 350 meson_parm_write(clk->map, &pll->rst, 0); 351 352 if (meson_clk_pll_wait_lock(hw)) 353 return -EIO; 354 355 return 0; 356 } 357 358 static void meson_clk_pll_disable(struct clk_hw *hw) 359 { 360 struct clk_regmap *clk = to_clk_regmap(hw); 361 struct meson_clk_pll_data *pll = meson_clk_pll_data(clk); 362 363 /* Put the pll is in reset */ 364 meson_parm_write(clk->map, &pll->rst, 1); 365 366 /* Disable the pll */ 367 meson_parm_write(clk->map, &pll->en, 0); 368 } 369 370 static int meson_clk_pll_set_rate(struct clk_hw *hw, unsigned long rate, 371 unsigned long parent_rate) 372 { 373 struct clk_regmap *clk = to_clk_regmap(hw); 374 struct meson_clk_pll_data *pll = meson_clk_pll_data(clk); 375 unsigned int enabled, m, n, frac = 0; 376 unsigned long old_rate; 377 int ret; 378 379 if (parent_rate == 0 || rate == 0) 380 return -EINVAL; 381 382 old_rate = clk_hw_get_rate(hw); 383 384 ret = meson_clk_get_pll_settings(rate, parent_rate, &m, &n, pll); 385 if (ret) 386 return ret; 387 388 enabled = meson_parm_read(clk->map, &pll->en); 389 if (enabled) 390 meson_clk_pll_disable(hw); 391 392 meson_parm_write(clk->map, &pll->n, n); 393 meson_parm_write(clk->map, &pll->m, m); 394 395 if (MESON_PARM_APPLICABLE(&pll->frac)) { 396 frac = __pll_params_with_frac(rate, parent_rate, m, n, pll); 397 meson_parm_write(clk->map, &pll->frac, frac); 398 } 399 400 /* If the pll is stopped, bail out now */ 401 if (!enabled) 402 return 0; 403 404 ret = meson_clk_pll_enable(hw); 405 if (ret) { 406 pr_warn("%s: pll did not lock, trying to restore old rate %lu\n", 407 __func__, old_rate); 408 /* 409 * FIXME: Do we really need/want this HACK ? 410 * It looks unsafe. what happens if the clock gets into a 411 * broken state and we can't lock back on the old_rate ? Looks 412 * like an infinite recursion is possible 413 */ 414 meson_clk_pll_set_rate(hw, old_rate, parent_rate); 415 } 416 417 return ret; 418 } 419 420 /* 421 * The Meson G12A PCIE PLL is fined tuned to deliver a very precise 422 * 100MHz reference clock for the PCIe Analog PHY, and thus requires 423 * a strict register sequence to enable the PLL. 424 * To simplify, re-use the _init() op to enable the PLL and keep 425 * the other ops except set_rate since the rate is fixed. 426 */ 427 const struct clk_ops meson_clk_pcie_pll_ops = { 428 .recalc_rate = meson_clk_pll_recalc_rate, 429 .determine_rate = meson_clk_pll_determine_rate, 430 .is_enabled = meson_clk_pll_is_enabled, 431 .enable = meson_clk_pcie_pll_enable, 432 .disable = meson_clk_pll_disable 433 }; 434 EXPORT_SYMBOL_GPL(meson_clk_pcie_pll_ops); 435 436 const struct clk_ops meson_clk_pll_ops = { 437 .init = meson_clk_pll_init, 438 .recalc_rate = meson_clk_pll_recalc_rate, 439 .determine_rate = meson_clk_pll_determine_rate, 440 .set_rate = meson_clk_pll_set_rate, 441 .is_enabled = meson_clk_pll_is_enabled, 442 .enable = meson_clk_pll_enable, 443 .disable = meson_clk_pll_disable 444 }; 445 EXPORT_SYMBOL_GPL(meson_clk_pll_ops); 446 447 const struct clk_ops meson_clk_pll_ro_ops = { 448 .recalc_rate = meson_clk_pll_recalc_rate, 449 .is_enabled = meson_clk_pll_is_enabled, 450 }; 451 EXPORT_SYMBOL_GPL(meson_clk_pll_ro_ops); 452 453 MODULE_DESCRIPTION("Amlogic PLL driver"); 454 MODULE_AUTHOR("Carlo Caione <carlo@endlessm.com>"); 455 MODULE_AUTHOR("Jerome Brunet <jbrunet@baylibre.com>"); 456 MODULE_LICENSE("GPL v2"); 457