Commit | Line | Data |
---|---|---|
c942fddf | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
1459c837 SB |
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. | |
d9d4944d | 7 | * Copyright (C) 2011 - 2021 Xilinx Inc. |
1459c837 SB |
8 | * |
9 | * Author: Guenter Roeck <guenter.roeck@ericsson.com> | |
10 | * Sören Brinkmann <soren.brinkmann@xilinx.com> | |
1459c837 SB |
11 | */ |
12 | ||
530b544e | 13 | #include <linux/clk.h> |
1459c837 SB |
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 | |
d9d4944d | 126 | * @skip_recall: If true, don't recall NVM into RAM |
1459c837 SB |
127 | * Returns 0 on success, negative errno otherwise. |
128 | */ | |
d9d4944d SN |
129 | static int si570_get_defaults(struct clk_si570 *data, u64 fout, |
130 | bool skip_recall) | |
1459c837 SB |
131 | { |
132 | int err; | |
133 | u64 fdco; | |
134 | ||
d9d4944d SN |
135 | if (!skip_recall) |
136 | regmap_write(data->regmap, SI570_REG_CONTROL, | |
137 | SI570_CNTRL_RECALL); | |
1459c837 SB |
138 | |
139 | err = si570_get_divs(data, &data->rfreq, &data->n1, &data->hs_div); | |
140 | if (err) | |
141 | return err; | |
142 | ||
143 | /* | |
144 | * Accept optional precision loss to avoid arithmetic overflows. | |
145 | * Acceptable per Silicon Labs Application Note AN334. | |
146 | */ | |
147 | fdco = fout * data->n1 * data->hs_div; | |
148 | if (fdco >= (1LL << 36)) | |
149 | data->fxtal = div64_u64(fdco << 24, data->rfreq >> 4); | |
150 | else | |
151 | data->fxtal = div64_u64(fdco << 28, data->rfreq); | |
152 | ||
153 | data->frequency = fout; | |
154 | ||
155 | return 0; | |
156 | } | |
157 | ||
158 | /** | |
159 | * si570_update_rfreq() - Update clock multiplier | |
160 | * @data: Driver data structure | |
161 | * Passes on regmap_bulk_write() return value. | |
162 | */ | |
163 | static int si570_update_rfreq(struct clk_si570 *data) | |
164 | { | |
165 | u8 reg[5]; | |
166 | ||
167 | reg[0] = ((data->n1 - 1) << 6) | | |
168 | ((data->rfreq >> 32) & RFREQ_37_32_MASK); | |
169 | reg[1] = (data->rfreq >> 24) & 0xff; | |
170 | reg[2] = (data->rfreq >> 16) & 0xff; | |
171 | reg[3] = (data->rfreq >> 8) & 0xff; | |
172 | reg[4] = data->rfreq & 0xff; | |
173 | ||
174 | return regmap_bulk_write(data->regmap, SI570_REG_N1_RFREQ0 + | |
175 | data->div_offset, reg, ARRAY_SIZE(reg)); | |
176 | } | |
177 | ||
178 | /** | |
179 | * si570_calc_divs() - Caluclate clock dividers | |
180 | * @frequency: Target frequency | |
181 | * @data: Driver data structure | |
182 | * @out_rfreq: RFREG fractional multiplier (output) | |
183 | * @out_n1: Clock divider N1 (output) | |
184 | * @out_hs_div: Clock divider HSDIV (output) | |
185 | * Returns 0 on success, negative errno otherwise. | |
186 | * | |
187 | * Calculate the clock dividers (@out_hs_div, @out_n1) and clock multiplier | |
188 | * (@out_rfreq) for a given target @frequency. | |
189 | */ | |
190 | static int si570_calc_divs(unsigned long frequency, struct clk_si570 *data, | |
191 | u64 *out_rfreq, unsigned int *out_n1, unsigned int *out_hs_div) | |
192 | { | |
193 | int i; | |
194 | unsigned int n1, hs_div; | |
195 | u64 fdco, best_fdco = ULLONG_MAX; | |
196 | static const uint8_t si570_hs_div_values[] = { 11, 9, 7, 6, 5, 4 }; | |
197 | ||
198 | for (i = 0; i < ARRAY_SIZE(si570_hs_div_values); i++) { | |
199 | hs_div = si570_hs_div_values[i]; | |
200 | /* Calculate lowest possible value for n1 */ | |
201 | n1 = div_u64(div_u64(FDCO_MIN, hs_div), frequency); | |
202 | if (!n1 || (n1 & 1)) | |
203 | n1++; | |
204 | while (n1 <= 128) { | |
205 | fdco = (u64)frequency * (u64)hs_div * (u64)n1; | |
206 | if (fdco > FDCO_MAX) | |
207 | break; | |
208 | if (fdco >= FDCO_MIN && fdco < best_fdco) { | |
209 | *out_n1 = n1; | |
210 | *out_hs_div = hs_div; | |
211 | *out_rfreq = div64_u64(fdco << 28, data->fxtal); | |
212 | best_fdco = fdco; | |
213 | } | |
214 | n1 += (n1 == 1 ? 1 : 2); | |
215 | } | |
216 | } | |
217 | ||
218 | if (best_fdco == ULLONG_MAX) | |
219 | return -EINVAL; | |
220 | ||
221 | return 0; | |
222 | } | |
223 | ||
224 | static unsigned long si570_recalc_rate(struct clk_hw *hw, | |
225 | unsigned long parent_rate) | |
226 | { | |
227 | int err; | |
228 | u64 rfreq, rate; | |
229 | unsigned int n1, hs_div; | |
230 | struct clk_si570 *data = to_clk_si570(hw); | |
231 | ||
232 | err = si570_get_divs(data, &rfreq, &n1, &hs_div); | |
233 | if (err) { | |
234 | dev_err(&data->i2c_client->dev, "unable to recalc rate\n"); | |
235 | return data->frequency; | |
236 | } | |
237 | ||
238 | rfreq = div_u64(rfreq, hs_div * n1); | |
239 | rate = (data->fxtal * rfreq) >> 28; | |
240 | ||
241 | return rate; | |
242 | } | |
243 | ||
244 | static long si570_round_rate(struct clk_hw *hw, unsigned long rate, | |
245 | unsigned long *parent_rate) | |
246 | { | |
247 | int err; | |
248 | u64 rfreq; | |
249 | unsigned int n1, hs_div; | |
250 | struct clk_si570 *data = to_clk_si570(hw); | |
251 | ||
252 | if (!rate) | |
253 | return 0; | |
254 | ||
255 | if (div64_u64(abs(rate - data->frequency) * 10000LL, | |
256 | data->frequency) < 35) { | |
257 | rfreq = div64_u64((data->rfreq * rate) + | |
258 | div64_u64(data->frequency, 2), data->frequency); | |
259 | n1 = data->n1; | |
260 | hs_div = data->hs_div; | |
261 | ||
262 | } else { | |
263 | err = si570_calc_divs(rate, data, &rfreq, &n1, &hs_div); | |
264 | if (err) { | |
265 | dev_err(&data->i2c_client->dev, | |
266 | "unable to round rate\n"); | |
267 | return 0; | |
268 | } | |
269 | } | |
270 | ||
271 | return rate; | |
272 | } | |
273 | ||
274 | /** | |
275 | * si570_set_frequency() - Adjust output frequency | |
276 | * @data: Driver data structure | |
277 | * @frequency: Target frequency | |
278 | * Returns 0 on success. | |
279 | * | |
280 | * Update output frequency for big frequency changes (> 3,500 ppm). | |
281 | */ | |
282 | static int si570_set_frequency(struct clk_si570 *data, unsigned long frequency) | |
283 | { | |
284 | int err; | |
285 | ||
286 | err = si570_calc_divs(frequency, data, &data->rfreq, &data->n1, | |
287 | &data->hs_div); | |
288 | if (err) | |
289 | return err; | |
290 | ||
291 | /* | |
292 | * The DCO reg should be accessed with a read-modify-write operation | |
293 | * per AN334 | |
294 | */ | |
295 | regmap_write(data->regmap, SI570_REG_FREEZE_DCO, SI570_FREEZE_DCO); | |
296 | regmap_write(data->regmap, SI570_REG_HS_N1 + data->div_offset, | |
297 | ((data->hs_div - HS_DIV_OFFSET) << HS_DIV_SHIFT) | | |
298 | (((data->n1 - 1) >> 2) & N1_6_2_MASK)); | |
299 | si570_update_rfreq(data); | |
300 | regmap_write(data->regmap, SI570_REG_FREEZE_DCO, 0); | |
301 | regmap_write(data->regmap, SI570_REG_CONTROL, SI570_CNTRL_NEWFREQ); | |
302 | ||
303 | /* Applying a new frequency can take up to 10ms */ | |
304 | usleep_range(10000, 12000); | |
305 | ||
306 | return 0; | |
307 | } | |
308 | ||
309 | /** | |
310 | * si570_set_frequency_small() - Adjust output frequency | |
311 | * @data: Driver data structure | |
312 | * @frequency: Target frequency | |
313 | * Returns 0 on success. | |
314 | * | |
315 | * Update output frequency for small frequency changes (< 3,500 ppm). | |
316 | */ | |
317 | static int si570_set_frequency_small(struct clk_si570 *data, | |
318 | unsigned long frequency) | |
319 | { | |
320 | /* | |
321 | * This is a re-implementation of DIV_ROUND_CLOSEST | |
322 | * using the div64_u64 function lieu of letting the compiler | |
323 | * insert EABI calls | |
324 | */ | |
325 | data->rfreq = div64_u64((data->rfreq * frequency) + | |
326 | div_u64(data->frequency, 2), data->frequency); | |
327 | regmap_write(data->regmap, SI570_REG_CONTROL, SI570_CNTRL_FREEZE_M); | |
328 | si570_update_rfreq(data); | |
329 | regmap_write(data->regmap, SI570_REG_CONTROL, 0); | |
330 | ||
331 | /* Applying a new frequency (small change) can take up to 100us */ | |
332 | usleep_range(100, 200); | |
333 | ||
334 | return 0; | |
335 | } | |
336 | ||
337 | static int si570_set_rate(struct clk_hw *hw, unsigned long rate, | |
338 | unsigned long parent_rate) | |
339 | { | |
340 | struct clk_si570 *data = to_clk_si570(hw); | |
341 | struct i2c_client *client = data->i2c_client; | |
342 | int err; | |
343 | ||
344 | if (rate < SI570_MIN_FREQ || rate > data->max_freq) { | |
345 | dev_err(&client->dev, | |
346 | "requested frequency %lu Hz is out of range\n", rate); | |
347 | return -EINVAL; | |
348 | } | |
349 | ||
350 | if (div64_u64(abs(rate - data->frequency) * 10000LL, | |
351 | data->frequency) < 35) | |
352 | err = si570_set_frequency_small(data, rate); | |
353 | else | |
354 | err = si570_set_frequency(data, rate); | |
355 | ||
356 | if (err) | |
357 | return err; | |
358 | ||
359 | data->frequency = rate; | |
360 | ||
361 | return 0; | |
362 | } | |
363 | ||
364 | static const struct clk_ops si570_clk_ops = { | |
365 | .recalc_rate = si570_recalc_rate, | |
366 | .round_rate = si570_round_rate, | |
367 | .set_rate = si570_set_rate, | |
368 | }; | |
369 | ||
370 | static bool si570_regmap_is_volatile(struct device *dev, unsigned int reg) | |
371 | { | |
372 | switch (reg) { | |
373 | case SI570_REG_CONTROL: | |
374 | return true; | |
375 | default: | |
376 | return false; | |
377 | } | |
378 | } | |
379 | ||
380 | static bool si570_regmap_is_writeable(struct device *dev, unsigned int reg) | |
381 | { | |
382 | switch (reg) { | |
383 | case SI570_REG_HS_N1 ... (SI570_REG_RFREQ4 + SI570_DIV_OFFSET_7PPM): | |
384 | case SI570_REG_CONTROL: | |
385 | case SI570_REG_FREEZE_DCO: | |
386 | return true; | |
387 | default: | |
388 | return false; | |
389 | } | |
390 | } | |
391 | ||
217c8df6 | 392 | static const struct regmap_config si570_regmap_config = { |
1459c837 SB |
393 | .reg_bits = 8, |
394 | .val_bits = 8, | |
395 | .cache_type = REGCACHE_RBTREE, | |
396 | .max_register = 137, | |
397 | .writeable_reg = si570_regmap_is_writeable, | |
398 | .volatile_reg = si570_regmap_is_volatile, | |
399 | }; | |
400 | ||
401 | static int si570_probe(struct i2c_client *client, | |
402 | const struct i2c_device_id *id) | |
403 | { | |
404 | struct clk_si570 *data; | |
405 | struct clk_init_data init; | |
1459c837 | 406 | u32 initial_fout, factory_fout, stability; |
d9d4944d | 407 | bool skip_recall; |
1459c837 SB |
408 | int err; |
409 | enum clk_si570_variant variant = id->driver_data; | |
410 | ||
411 | data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); | |
412 | if (!data) | |
413 | return -ENOMEM; | |
414 | ||
415 | init.ops = &si570_clk_ops; | |
803c4331 | 416 | init.flags = 0; |
1459c837 SB |
417 | init.num_parents = 0; |
418 | data->hw.init = &init; | |
419 | data->i2c_client = client; | |
420 | ||
421 | if (variant == si57x) { | |
422 | err = of_property_read_u32(client->dev.of_node, | |
423 | "temperature-stability", &stability); | |
424 | if (err) { | |
425 | dev_err(&client->dev, | |
426 | "'temperature-stability' property missing\n"); | |
427 | return err; | |
428 | } | |
429 | /* adjust register offsets for 7ppm devices */ | |
430 | if (stability == 7) | |
431 | data->div_offset = SI570_DIV_OFFSET_7PPM; | |
432 | ||
433 | data->max_freq = SI570_MAX_FREQ; | |
434 | } else { | |
435 | data->max_freq = SI598_MAX_FREQ; | |
436 | } | |
437 | ||
438 | if (of_property_read_string(client->dev.of_node, "clock-output-names", | |
439 | &init.name)) | |
440 | init.name = client->dev.of_node->name; | |
441 | ||
442 | err = of_property_read_u32(client->dev.of_node, "factory-fout", | |
443 | &factory_fout); | |
444 | if (err) { | |
445 | dev_err(&client->dev, "'factory-fout' property missing\n"); | |
446 | return err; | |
447 | } | |
448 | ||
d9d4944d SN |
449 | skip_recall = of_property_read_bool(client->dev.of_node, |
450 | "silabs,skip-recall"); | |
451 | ||
1459c837 SB |
452 | data->regmap = devm_regmap_init_i2c(client, &si570_regmap_config); |
453 | if (IS_ERR(data->regmap)) { | |
454 | dev_err(&client->dev, "failed to allocate register map\n"); | |
455 | return PTR_ERR(data->regmap); | |
456 | } | |
457 | ||
458 | i2c_set_clientdata(client, data); | |
d9d4944d | 459 | err = si570_get_defaults(data, factory_fout, skip_recall); |
1459c837 SB |
460 | if (err) |
461 | return err; | |
462 | ||
a340dae9 SB |
463 | err = devm_clk_hw_register(&client->dev, &data->hw); |
464 | if (err) { | |
1459c837 | 465 | dev_err(&client->dev, "clock registration failed\n"); |
a340dae9 | 466 | return err; |
1459c837 | 467 | } |
a340dae9 SB |
468 | err = of_clk_add_hw_provider(client->dev.of_node, of_clk_hw_simple_get, |
469 | &data->hw); | |
1459c837 SB |
470 | if (err) { |
471 | dev_err(&client->dev, "unable to add clk provider\n"); | |
472 | return err; | |
473 | } | |
474 | ||
475 | /* Read the requested initial output frequency from device tree */ | |
476 | if (!of_property_read_u32(client->dev.of_node, "clock-frequency", | |
477 | &initial_fout)) { | |
a340dae9 | 478 | err = clk_set_rate(data->hw.clk, initial_fout); |
1459c837 SB |
479 | if (err) { |
480 | of_clk_del_provider(client->dev.of_node); | |
481 | return err; | |
482 | } | |
483 | } | |
484 | ||
485 | /* Display a message indicating that we've successfully registered */ | |
486 | dev_info(&client->dev, "registered, current frequency %llu Hz\n", | |
487 | data->frequency); | |
488 | ||
489 | return 0; | |
490 | } | |
491 | ||
492 | static int si570_remove(struct i2c_client *client) | |
493 | { | |
494 | of_clk_del_provider(client->dev.of_node); | |
495 | return 0; | |
496 | } | |
497 | ||
498 | static const struct i2c_device_id si570_id[] = { | |
499 | { "si570", si57x }, | |
500 | { "si571", si57x }, | |
501 | { "si598", si59x }, | |
502 | { "si599", si59x }, | |
503 | { } | |
504 | }; | |
505 | MODULE_DEVICE_TABLE(i2c, si570_id); | |
506 | ||
507 | static const struct of_device_id clk_si570_of_match[] = { | |
508 | { .compatible = "silabs,si570" }, | |
509 | { .compatible = "silabs,si571" }, | |
510 | { .compatible = "silabs,si598" }, | |
511 | { .compatible = "silabs,si599" }, | |
512 | { }, | |
513 | }; | |
514 | MODULE_DEVICE_TABLE(of, clk_si570_of_match); | |
515 | ||
516 | static struct i2c_driver si570_driver = { | |
517 | .driver = { | |
518 | .name = "si570", | |
e8ab2f11 | 519 | .of_match_table = clk_si570_of_match, |
1459c837 SB |
520 | }, |
521 | .probe = si570_probe, | |
522 | .remove = si570_remove, | |
523 | .id_table = si570_id, | |
524 | }; | |
525 | module_i2c_driver(si570_driver); | |
526 | ||
527 | MODULE_AUTHOR("Guenter Roeck <guenter.roeck@ericsson.com>"); | |
44731f5d | 528 | MODULE_AUTHOR("Soeren Brinkmann <soren.brinkmann@xilinx.com>"); |
1459c837 SB |
529 | MODULE_DESCRIPTION("Si570 driver"); |
530 | MODULE_LICENSE("GPL"); |