1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Driver for Silicon Labs Si570/Si571 Programmable XO/VCXO 4 * 5 * Copyright (C) 2010, 2011 Ericsson AB. 6 * Copyright (C) 2011 Guenter Roeck. 7 * Copyright (C) 2011 - 2013 Xilinx Inc. 8 * 9 * Author: Guenter Roeck <guenter.roeck@ericsson.com> 10 * Sören Brinkmann <soren.brinkmann@xilinx.com> 11 */ 12 13 #include <linux/clk.h> 14 #include <linux/clk-provider.h> 15 #include <linux/delay.h> 16 #include <linux/module.h> 17 #include <linux/i2c.h> 18 #include <linux/regmap.h> 19 #include <linux/slab.h> 20 21 /* Si570 registers */ 22 #define SI570_REG_HS_N1 7 23 #define SI570_REG_N1_RFREQ0 8 24 #define SI570_REG_RFREQ1 9 25 #define SI570_REG_RFREQ2 10 26 #define SI570_REG_RFREQ3 11 27 #define SI570_REG_RFREQ4 12 28 #define SI570_REG_CONTROL 135 29 #define SI570_REG_FREEZE_DCO 137 30 #define SI570_DIV_OFFSET_7PPM 6 31 32 #define HS_DIV_SHIFT 5 33 #define HS_DIV_MASK 0xe0 34 #define HS_DIV_OFFSET 4 35 #define N1_6_2_MASK 0x1f 36 #define N1_1_0_MASK 0xc0 37 #define RFREQ_37_32_MASK 0x3f 38 39 #define SI570_MIN_FREQ 10000000L 40 #define SI570_MAX_FREQ 1417500000L 41 #define SI598_MAX_FREQ 525000000L 42 43 #define FDCO_MIN 4850000000LL 44 #define FDCO_MAX 5670000000LL 45 46 #define SI570_CNTRL_RECALL (1 << 0) 47 #define SI570_CNTRL_FREEZE_M (1 << 5) 48 #define SI570_CNTRL_NEWFREQ (1 << 6) 49 50 #define SI570_FREEZE_DCO (1 << 4) 51 52 /** 53 * struct clk_si570: 54 * @hw: Clock hw struct 55 * @regmap: Device's regmap 56 * @div_offset: Rgister offset for dividers 57 * @max_freq: Maximum frequency for this device 58 * @fxtal: Factory xtal frequency 59 * @n1: Clock divider N1 60 * @hs_div: Clock divider HSDIV 61 * @rfreq: Clock multiplier RFREQ 62 * @frequency: Current output frequency 63 * @i2c_client: I2C client pointer 64 */ 65 struct clk_si570 { 66 struct clk_hw hw; 67 struct regmap *regmap; 68 unsigned int div_offset; 69 u64 max_freq; 70 u64 fxtal; 71 unsigned int n1; 72 unsigned int hs_div; 73 u64 rfreq; 74 u64 frequency; 75 struct i2c_client *i2c_client; 76 }; 77 #define to_clk_si570(_hw) container_of(_hw, struct clk_si570, hw) 78 79 enum clk_si570_variant { 80 si57x, 81 si59x 82 }; 83 84 /** 85 * si570_get_divs() - Read clock dividers from HW 86 * @data: Pointer to struct clk_si570 87 * @rfreq: Fractional multiplier (output) 88 * @n1: Divider N1 (output) 89 * @hs_div: Divider HSDIV (output) 90 * Returns 0 on success, negative errno otherwise. 91 * 92 * Retrieve clock dividers and multipliers from the HW. 93 */ 94 static int si570_get_divs(struct clk_si570 *data, u64 *rfreq, 95 unsigned int *n1, unsigned int *hs_div) 96 { 97 int err; 98 u8 reg[6]; 99 u64 tmp; 100 101 err = regmap_bulk_read(data->regmap, SI570_REG_HS_N1 + data->div_offset, 102 reg, ARRAY_SIZE(reg)); 103 if (err) 104 return err; 105 106 *hs_div = ((reg[0] & HS_DIV_MASK) >> HS_DIV_SHIFT) + HS_DIV_OFFSET; 107 *n1 = ((reg[0] & N1_6_2_MASK) << 2) + ((reg[1] & N1_1_0_MASK) >> 6) + 1; 108 /* Handle invalid cases */ 109 if (*n1 > 1) 110 *n1 &= ~1; 111 112 tmp = reg[1] & RFREQ_37_32_MASK; 113 tmp = (tmp << 8) + reg[2]; 114 tmp = (tmp << 8) + reg[3]; 115 tmp = (tmp << 8) + reg[4]; 116 tmp = (tmp << 8) + reg[5]; 117 *rfreq = tmp; 118 119 return 0; 120 } 121 122 /** 123 * si570_get_defaults() - Get default values 124 * @data: Driver data structure 125 * @fout: Factory frequency output 126 * Returns 0 on success, negative errno otherwise. 127 */ 128 static int si570_get_defaults(struct clk_si570 *data, u64 fout) 129 { 130 int err; 131 u64 fdco; 132 133 regmap_write(data->regmap, SI570_REG_CONTROL, SI570_CNTRL_RECALL); 134 135 err = si570_get_divs(data, &data->rfreq, &data->n1, &data->hs_div); 136 if (err) 137 return err; 138 139 /* 140 * Accept optional precision loss to avoid arithmetic overflows. 141 * Acceptable per Silicon Labs Application Note AN334. 142 */ 143 fdco = fout * data->n1 * data->hs_div; 144 if (fdco >= (1LL << 36)) 145 data->fxtal = div64_u64(fdco << 24, data->rfreq >> 4); 146 else 147 data->fxtal = div64_u64(fdco << 28, data->rfreq); 148 149 data->frequency = fout; 150 151 return 0; 152 } 153 154 /** 155 * si570_update_rfreq() - Update clock multiplier 156 * @data: Driver data structure 157 * Passes on regmap_bulk_write() return value. 158 */ 159 static int si570_update_rfreq(struct clk_si570 *data) 160 { 161 u8 reg[5]; 162 163 reg[0] = ((data->n1 - 1) << 6) | 164 ((data->rfreq >> 32) & RFREQ_37_32_MASK); 165 reg[1] = (data->rfreq >> 24) & 0xff; 166 reg[2] = (data->rfreq >> 16) & 0xff; 167 reg[3] = (data->rfreq >> 8) & 0xff; 168 reg[4] = data->rfreq & 0xff; 169 170 return regmap_bulk_write(data->regmap, SI570_REG_N1_RFREQ0 + 171 data->div_offset, reg, ARRAY_SIZE(reg)); 172 } 173 174 /** 175 * si570_calc_divs() - Caluclate clock dividers 176 * @frequency: Target frequency 177 * @data: Driver data structure 178 * @out_rfreq: RFREG fractional multiplier (output) 179 * @out_n1: Clock divider N1 (output) 180 * @out_hs_div: Clock divider HSDIV (output) 181 * Returns 0 on success, negative errno otherwise. 182 * 183 * Calculate the clock dividers (@out_hs_div, @out_n1) and clock multiplier 184 * (@out_rfreq) for a given target @frequency. 185 */ 186 static int si570_calc_divs(unsigned long frequency, struct clk_si570 *data, 187 u64 *out_rfreq, unsigned int *out_n1, unsigned int *out_hs_div) 188 { 189 int i; 190 unsigned int n1, hs_div; 191 u64 fdco, best_fdco = ULLONG_MAX; 192 static const uint8_t si570_hs_div_values[] = { 11, 9, 7, 6, 5, 4 }; 193 194 for (i = 0; i < ARRAY_SIZE(si570_hs_div_values); i++) { 195 hs_div = si570_hs_div_values[i]; 196 /* Calculate lowest possible value for n1 */ 197 n1 = div_u64(div_u64(FDCO_MIN, hs_div), frequency); 198 if (!n1 || (n1 & 1)) 199 n1++; 200 while (n1 <= 128) { 201 fdco = (u64)frequency * (u64)hs_div * (u64)n1; 202 if (fdco > FDCO_MAX) 203 break; 204 if (fdco >= FDCO_MIN && fdco < best_fdco) { 205 *out_n1 = n1; 206 *out_hs_div = hs_div; 207 *out_rfreq = div64_u64(fdco << 28, data->fxtal); 208 best_fdco = fdco; 209 } 210 n1 += (n1 == 1 ? 1 : 2); 211 } 212 } 213 214 if (best_fdco == ULLONG_MAX) 215 return -EINVAL; 216 217 return 0; 218 } 219 220 static unsigned long si570_recalc_rate(struct clk_hw *hw, 221 unsigned long parent_rate) 222 { 223 int err; 224 u64 rfreq, rate; 225 unsigned int n1, hs_div; 226 struct clk_si570 *data = to_clk_si570(hw); 227 228 err = si570_get_divs(data, &rfreq, &n1, &hs_div); 229 if (err) { 230 dev_err(&data->i2c_client->dev, "unable to recalc rate\n"); 231 return data->frequency; 232 } 233 234 rfreq = div_u64(rfreq, hs_div * n1); 235 rate = (data->fxtal * rfreq) >> 28; 236 237 return rate; 238 } 239 240 static long si570_round_rate(struct clk_hw *hw, unsigned long rate, 241 unsigned long *parent_rate) 242 { 243 int err; 244 u64 rfreq; 245 unsigned int n1, hs_div; 246 struct clk_si570 *data = to_clk_si570(hw); 247 248 if (!rate) 249 return 0; 250 251 if (div64_u64(abs(rate - data->frequency) * 10000LL, 252 data->frequency) < 35) { 253 rfreq = div64_u64((data->rfreq * rate) + 254 div64_u64(data->frequency, 2), data->frequency); 255 n1 = data->n1; 256 hs_div = data->hs_div; 257 258 } else { 259 err = si570_calc_divs(rate, data, &rfreq, &n1, &hs_div); 260 if (err) { 261 dev_err(&data->i2c_client->dev, 262 "unable to round rate\n"); 263 return 0; 264 } 265 } 266 267 return rate; 268 } 269 270 /** 271 * si570_set_frequency() - Adjust output frequency 272 * @data: Driver data structure 273 * @frequency: Target frequency 274 * Returns 0 on success. 275 * 276 * Update output frequency for big frequency changes (> 3,500 ppm). 277 */ 278 static int si570_set_frequency(struct clk_si570 *data, unsigned long frequency) 279 { 280 int err; 281 282 err = si570_calc_divs(frequency, data, &data->rfreq, &data->n1, 283 &data->hs_div); 284 if (err) 285 return err; 286 287 /* 288 * The DCO reg should be accessed with a read-modify-write operation 289 * per AN334 290 */ 291 regmap_write(data->regmap, SI570_REG_FREEZE_DCO, SI570_FREEZE_DCO); 292 regmap_write(data->regmap, SI570_REG_HS_N1 + data->div_offset, 293 ((data->hs_div - HS_DIV_OFFSET) << HS_DIV_SHIFT) | 294 (((data->n1 - 1) >> 2) & N1_6_2_MASK)); 295 si570_update_rfreq(data); 296 regmap_write(data->regmap, SI570_REG_FREEZE_DCO, 0); 297 regmap_write(data->regmap, SI570_REG_CONTROL, SI570_CNTRL_NEWFREQ); 298 299 /* Applying a new frequency can take up to 10ms */ 300 usleep_range(10000, 12000); 301 302 return 0; 303 } 304 305 /** 306 * si570_set_frequency_small() - Adjust output frequency 307 * @data: Driver data structure 308 * @frequency: Target frequency 309 * Returns 0 on success. 310 * 311 * Update output frequency for small frequency changes (< 3,500 ppm). 312 */ 313 static int si570_set_frequency_small(struct clk_si570 *data, 314 unsigned long frequency) 315 { 316 /* 317 * This is a re-implementation of DIV_ROUND_CLOSEST 318 * using the div64_u64 function lieu of letting the compiler 319 * insert EABI calls 320 */ 321 data->rfreq = div64_u64((data->rfreq * frequency) + 322 div_u64(data->frequency, 2), data->frequency); 323 regmap_write(data->regmap, SI570_REG_CONTROL, SI570_CNTRL_FREEZE_M); 324 si570_update_rfreq(data); 325 regmap_write(data->regmap, SI570_REG_CONTROL, 0); 326 327 /* Applying a new frequency (small change) can take up to 100us */ 328 usleep_range(100, 200); 329 330 return 0; 331 } 332 333 static int si570_set_rate(struct clk_hw *hw, unsigned long rate, 334 unsigned long parent_rate) 335 { 336 struct clk_si570 *data = to_clk_si570(hw); 337 struct i2c_client *client = data->i2c_client; 338 int err; 339 340 if (rate < SI570_MIN_FREQ || rate > data->max_freq) { 341 dev_err(&client->dev, 342 "requested frequency %lu Hz is out of range\n", rate); 343 return -EINVAL; 344 } 345 346 if (div64_u64(abs(rate - data->frequency) * 10000LL, 347 data->frequency) < 35) 348 err = si570_set_frequency_small(data, rate); 349 else 350 err = si570_set_frequency(data, rate); 351 352 if (err) 353 return err; 354 355 data->frequency = rate; 356 357 return 0; 358 } 359 360 static const struct clk_ops si570_clk_ops = { 361 .recalc_rate = si570_recalc_rate, 362 .round_rate = si570_round_rate, 363 .set_rate = si570_set_rate, 364 }; 365 366 static bool si570_regmap_is_volatile(struct device *dev, unsigned int reg) 367 { 368 switch (reg) { 369 case SI570_REG_CONTROL: 370 return true; 371 default: 372 return false; 373 } 374 } 375 376 static bool si570_regmap_is_writeable(struct device *dev, unsigned int reg) 377 { 378 switch (reg) { 379 case SI570_REG_HS_N1 ... (SI570_REG_RFREQ4 + SI570_DIV_OFFSET_7PPM): 380 case SI570_REG_CONTROL: 381 case SI570_REG_FREEZE_DCO: 382 return true; 383 default: 384 return false; 385 } 386 } 387 388 static const struct regmap_config si570_regmap_config = { 389 .reg_bits = 8, 390 .val_bits = 8, 391 .cache_type = REGCACHE_RBTREE, 392 .max_register = 137, 393 .writeable_reg = si570_regmap_is_writeable, 394 .volatile_reg = si570_regmap_is_volatile, 395 }; 396 397 static int si570_probe(struct i2c_client *client, 398 const struct i2c_device_id *id) 399 { 400 struct clk_si570 *data; 401 struct clk_init_data init; 402 u32 initial_fout, factory_fout, stability; 403 int err; 404 enum clk_si570_variant variant = id->driver_data; 405 406 data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); 407 if (!data) 408 return -ENOMEM; 409 410 init.ops = &si570_clk_ops; 411 init.flags = 0; 412 init.num_parents = 0; 413 data->hw.init = &init; 414 data->i2c_client = client; 415 416 if (variant == si57x) { 417 err = of_property_read_u32(client->dev.of_node, 418 "temperature-stability", &stability); 419 if (err) { 420 dev_err(&client->dev, 421 "'temperature-stability' property missing\n"); 422 return err; 423 } 424 /* adjust register offsets for 7ppm devices */ 425 if (stability == 7) 426 data->div_offset = SI570_DIV_OFFSET_7PPM; 427 428 data->max_freq = SI570_MAX_FREQ; 429 } else { 430 data->max_freq = SI598_MAX_FREQ; 431 } 432 433 if (of_property_read_string(client->dev.of_node, "clock-output-names", 434 &init.name)) 435 init.name = client->dev.of_node->name; 436 437 err = of_property_read_u32(client->dev.of_node, "factory-fout", 438 &factory_fout); 439 if (err) { 440 dev_err(&client->dev, "'factory-fout' property missing\n"); 441 return err; 442 } 443 444 data->regmap = devm_regmap_init_i2c(client, &si570_regmap_config); 445 if (IS_ERR(data->regmap)) { 446 dev_err(&client->dev, "failed to allocate register map\n"); 447 return PTR_ERR(data->regmap); 448 } 449 450 i2c_set_clientdata(client, data); 451 err = si570_get_defaults(data, factory_fout); 452 if (err) 453 return err; 454 455 err = devm_clk_hw_register(&client->dev, &data->hw); 456 if (err) { 457 dev_err(&client->dev, "clock registration failed\n"); 458 return err; 459 } 460 err = of_clk_add_hw_provider(client->dev.of_node, of_clk_hw_simple_get, 461 &data->hw); 462 if (err) { 463 dev_err(&client->dev, "unable to add clk provider\n"); 464 return err; 465 } 466 467 /* Read the requested initial output frequency from device tree */ 468 if (!of_property_read_u32(client->dev.of_node, "clock-frequency", 469 &initial_fout)) { 470 err = clk_set_rate(data->hw.clk, initial_fout); 471 if (err) { 472 of_clk_del_provider(client->dev.of_node); 473 return err; 474 } 475 } 476 477 /* Display a message indicating that we've successfully registered */ 478 dev_info(&client->dev, "registered, current frequency %llu Hz\n", 479 data->frequency); 480 481 return 0; 482 } 483 484 static int si570_remove(struct i2c_client *client) 485 { 486 of_clk_del_provider(client->dev.of_node); 487 return 0; 488 } 489 490 static const struct i2c_device_id si570_id[] = { 491 { "si570", si57x }, 492 { "si571", si57x }, 493 { "si598", si59x }, 494 { "si599", si59x }, 495 { } 496 }; 497 MODULE_DEVICE_TABLE(i2c, si570_id); 498 499 static const struct of_device_id clk_si570_of_match[] = { 500 { .compatible = "silabs,si570" }, 501 { .compatible = "silabs,si571" }, 502 { .compatible = "silabs,si598" }, 503 { .compatible = "silabs,si599" }, 504 { }, 505 }; 506 MODULE_DEVICE_TABLE(of, clk_si570_of_match); 507 508 static struct i2c_driver si570_driver = { 509 .driver = { 510 .name = "si570", 511 .of_match_table = clk_si570_of_match, 512 }, 513 .probe = si570_probe, 514 .remove = si570_remove, 515 .id_table = si570_id, 516 }; 517 module_i2c_driver(si570_driver); 518 519 MODULE_AUTHOR("Guenter Roeck <guenter.roeck@ericsson.com>"); 520 MODULE_AUTHOR("Soeren Brinkmann <soren.brinkmann@xilinx.com>"); 521 MODULE_DESCRIPTION("Si570 driver"); 522 MODULE_LICENSE("GPL"); 523