1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
4 *
5 * Authors:
6 * Serge Semin <Sergey.Semin@baikalelectronics.ru>
7 * Dmitry Dunaev <dmitry.dunaev@baikalelectronics.ru>
8 *
9 * Baikal-T1 CCU PLL interface driver
10 */
11
12#define pr_fmt(fmt) "bt1-ccu-pll: " fmt
13
14#include <linux/kernel.h>
15#include <linux/printk.h>
16#include <linux/limits.h>
17#include <linux/bits.h>
18#include <linux/bitfield.h>
19#include <linux/slab.h>
20#include <linux/clk-provider.h>
21#include <linux/of.h>
22#include <linux/spinlock.h>
23#include <linux/regmap.h>
24#include <linux/iopoll.h>
25#include <linux/time64.h>
26#include <linux/rational.h>
27#include <linux/debugfs.h>
28
29#include "ccu-pll.h"
30
31#define CCU_PLL_CTL 0x000
32#define CCU_PLL_CTL_EN BIT(0)
33#define CCU_PLL_CTL_RST BIT(1)
34#define CCU_PLL_CTL_CLKR_FLD 2
35#define CCU_PLL_CTL_CLKR_MASK GENMASK(7, CCU_PLL_CTL_CLKR_FLD)
36#define CCU_PLL_CTL_CLKF_FLD 8
37#define CCU_PLL_CTL_CLKF_MASK GENMASK(20, CCU_PLL_CTL_CLKF_FLD)
38#define CCU_PLL_CTL_CLKOD_FLD 21
39#define CCU_PLL_CTL_CLKOD_MASK GENMASK(24, CCU_PLL_CTL_CLKOD_FLD)
40#define CCU_PLL_CTL_BYPASS BIT(30)
41#define CCU_PLL_CTL_LOCK BIT(31)
42#define CCU_PLL_CTL1 0x004
43#define CCU_PLL_CTL1_BWADJ_FLD 3
44#define CCU_PLL_CTL1_BWADJ_MASK GENMASK(14, CCU_PLL_CTL1_BWADJ_FLD)
45
46#define CCU_PLL_LOCK_CHECK_RETRIES 50
47
48#define CCU_PLL_NR_MAX \
49 ((CCU_PLL_CTL_CLKR_MASK >> CCU_PLL_CTL_CLKR_FLD) + 1)
50#define CCU_PLL_NF_MAX \
51 ((CCU_PLL_CTL_CLKF_MASK >> (CCU_PLL_CTL_CLKF_FLD + 1)) + 1)
52#define CCU_PLL_OD_MAX \
53 ((CCU_PLL_CTL_CLKOD_MASK >> CCU_PLL_CTL_CLKOD_FLD) + 1)
54#define CCU_PLL_NB_MAX \
55 ((CCU_PLL_CTL1_BWADJ_MASK >> CCU_PLL_CTL1_BWADJ_FLD) + 1)
56#define CCU_PLL_FDIV_MIN 427000UL
57#define CCU_PLL_FDIV_MAX 3500000000UL
58#define CCU_PLL_FOUT_MIN 200000000UL
59#define CCU_PLL_FOUT_MAX 2500000000UL
60#define CCU_PLL_FVCO_MIN 700000000UL
61#define CCU_PLL_FVCO_MAX 3500000000UL
62#define CCU_PLL_CLKOD_FACTOR 2
63
64static inline unsigned long ccu_pll_lock_delay_us(unsigned long ref_clk,
65 unsigned long nr)
66{
67 u64 us = 500ULL * nr * USEC_PER_SEC;
68
69 do_div(us, ref_clk);
70
71 return us;
72}
73
74static inline unsigned long ccu_pll_calc_freq(unsigned long ref_clk,
75 unsigned long nr,
76 unsigned long nf,
77 unsigned long od)
78{
79 u64 tmp = ref_clk;
80
81 do_div(tmp, nr);
82 tmp *= nf;
83 do_div(tmp, od);
84
85 return tmp;
86}
87
88static int ccu_pll_reset(struct ccu_pll *pll, unsigned long ref_clk,
89 unsigned long nr)
90{
91 unsigned long ud, ut;
92 u32 val;
93
94 ud = ccu_pll_lock_delay_us(ref_clk, nr);
95 ut = ud * CCU_PLL_LOCK_CHECK_RETRIES;
96
97 regmap_update_bits(map: pll->sys_regs, reg: pll->reg_ctl,
98 CCU_PLL_CTL_RST, CCU_PLL_CTL_RST);
99
100 return regmap_read_poll_timeout_atomic(pll->sys_regs, pll->reg_ctl, val,
101 val & CCU_PLL_CTL_LOCK, ud, ut);
102}
103
104static int ccu_pll_enable(struct clk_hw *hw)
105{
106 struct clk_hw *parent_hw = clk_hw_get_parent(hw);
107 struct ccu_pll *pll = to_ccu_pll(hw);
108 unsigned long flags;
109 u32 val = 0;
110 int ret;
111
112 if (!parent_hw) {
113 pr_err("Can't enable '%s' with no parent", clk_hw_get_name(hw));
114 return -EINVAL;
115 }
116
117 regmap_read(map: pll->sys_regs, reg: pll->reg_ctl, val: &val);
118 if (val & CCU_PLL_CTL_EN)
119 return 0;
120
121 spin_lock_irqsave(&pll->lock, flags);
122 regmap_write(map: pll->sys_regs, reg: pll->reg_ctl, val: val | CCU_PLL_CTL_EN);
123 ret = ccu_pll_reset(pll, ref_clk: clk_hw_get_rate(hw: parent_hw),
124 FIELD_GET(CCU_PLL_CTL_CLKR_MASK, val) + 1);
125 spin_unlock_irqrestore(lock: &pll->lock, flags);
126 if (ret)
127 pr_err("PLL '%s' reset timed out\n", clk_hw_get_name(hw));
128
129 return ret;
130}
131
132static void ccu_pll_disable(struct clk_hw *hw)
133{
134 struct ccu_pll *pll = to_ccu_pll(hw);
135 unsigned long flags;
136
137 spin_lock_irqsave(&pll->lock, flags);
138 regmap_update_bits(map: pll->sys_regs, reg: pll->reg_ctl, CCU_PLL_CTL_EN, val: 0);
139 spin_unlock_irqrestore(lock: &pll->lock, flags);
140}
141
142static int ccu_pll_is_enabled(struct clk_hw *hw)
143{
144 struct ccu_pll *pll = to_ccu_pll(hw);
145 u32 val = 0;
146
147 regmap_read(map: pll->sys_regs, reg: pll->reg_ctl, val: &val);
148
149 return !!(val & CCU_PLL_CTL_EN);
150}
151
152static unsigned long ccu_pll_recalc_rate(struct clk_hw *hw,
153 unsigned long parent_rate)
154{
155 struct ccu_pll *pll = to_ccu_pll(hw);
156 unsigned long nr, nf, od;
157 u32 val = 0;
158
159 regmap_read(map: pll->sys_regs, reg: pll->reg_ctl, val: &val);
160 nr = FIELD_GET(CCU_PLL_CTL_CLKR_MASK, val) + 1;
161 nf = FIELD_GET(CCU_PLL_CTL_CLKF_MASK, val) + 1;
162 od = FIELD_GET(CCU_PLL_CTL_CLKOD_MASK, val) + 1;
163
164 return ccu_pll_calc_freq(ref_clk: parent_rate, nr, nf, od);
165}
166
167static void ccu_pll_calc_factors(unsigned long rate, unsigned long parent_rate,
168 unsigned long *nr, unsigned long *nf,
169 unsigned long *od)
170{
171 unsigned long err, freq, min_err = ULONG_MAX;
172 unsigned long num, denom, n1, d1, nri;
173 unsigned long nr_max, nf_max, od_max;
174
175 /*
176 * Make sure PLL is working with valid input signal (Fdiv). If
177 * you want to speed the function up just reduce CCU_PLL_NR_MAX.
178 * This will cause a worse approximation though.
179 */
180 nri = (parent_rate / CCU_PLL_FDIV_MAX) + 1;
181 nr_max = min(parent_rate / CCU_PLL_FDIV_MIN, CCU_PLL_NR_MAX);
182
183 /*
184 * Find a closest [nr;nf;od] vector taking into account the
185 * limitations like: 1) 700MHz <= Fvco <= 3.5GHz, 2) PLL Od is
186 * either 1 or even number within the acceptable range (alas 1s
187 * is also excluded by the next loop).
188 */
189 for (; nri <= nr_max; ++nri) {
190 /* Use Od factor to fulfill the limitation 2). */
191 num = CCU_PLL_CLKOD_FACTOR * rate;
192 denom = parent_rate / nri;
193
194 /*
195 * Make sure Fvco is within the acceptable range to fulfill
196 * the condition 1). Note due to the CCU_PLL_CLKOD_FACTOR value
197 * the actual upper limit is also divided by that factor.
198 * It's not big problem for us since practically there is no
199 * need in clocks with that high frequency.
200 */
201 nf_max = min(CCU_PLL_FVCO_MAX / denom, CCU_PLL_NF_MAX);
202 od_max = CCU_PLL_OD_MAX / CCU_PLL_CLKOD_FACTOR;
203
204 /*
205 * Bypass the out-of-bound values, which can't be properly
206 * handled by the rational fraction approximation algorithm.
207 */
208 if (num / denom >= nf_max) {
209 n1 = nf_max;
210 d1 = 1;
211 } else if (denom / num >= od_max) {
212 n1 = 1;
213 d1 = od_max;
214 } else {
215 rational_best_approximation(given_numerator: num, given_denominator: denom, max_numerator: nf_max, max_denominator: od_max,
216 best_numerator: &n1, best_denominator: &d1);
217 }
218
219 /* Select the best approximation of the target rate. */
220 freq = ccu_pll_calc_freq(ref_clk: parent_rate, nr: nri, nf: n1, od: d1);
221 err = abs((int64_t)freq - num);
222 if (err < min_err) {
223 min_err = err;
224 *nr = nri;
225 *nf = n1;
226 *od = CCU_PLL_CLKOD_FACTOR * d1;
227 }
228 }
229}
230
231static long ccu_pll_round_rate(struct clk_hw *hw, unsigned long rate,
232 unsigned long *parent_rate)
233{
234 unsigned long nr = 1, nf = 1, od = 1;
235
236 ccu_pll_calc_factors(rate, parent_rate: *parent_rate, nr: &nr, nf: &nf, od: &od);
237
238 return ccu_pll_calc_freq(ref_clk: *parent_rate, nr, nf, od);
239}
240
241/*
242 * This method is used for PLLs, which support the on-the-fly dividers
243 * adjustment. So there is no need in gating such clocks.
244 */
245static int ccu_pll_set_rate_reset(struct clk_hw *hw, unsigned long rate,
246 unsigned long parent_rate)
247{
248 struct ccu_pll *pll = to_ccu_pll(hw);
249 unsigned long nr, nf, od;
250 unsigned long flags;
251 u32 mask, val;
252 int ret;
253
254 ccu_pll_calc_factors(rate, parent_rate, nr: &nr, nf: &nf, od: &od);
255
256 mask = CCU_PLL_CTL_CLKR_MASK | CCU_PLL_CTL_CLKF_MASK |
257 CCU_PLL_CTL_CLKOD_MASK;
258 val = FIELD_PREP(CCU_PLL_CTL_CLKR_MASK, nr - 1) |
259 FIELD_PREP(CCU_PLL_CTL_CLKF_MASK, nf - 1) |
260 FIELD_PREP(CCU_PLL_CTL_CLKOD_MASK, od - 1);
261
262 spin_lock_irqsave(&pll->lock, flags);
263 regmap_update_bits(map: pll->sys_regs, reg: pll->reg_ctl, mask, val);
264 ret = ccu_pll_reset(pll, ref_clk: parent_rate, nr);
265 spin_unlock_irqrestore(lock: &pll->lock, flags);
266 if (ret)
267 pr_err("PLL '%s' reset timed out\n", clk_hw_get_name(hw));
268
269 return ret;
270}
271
272/*
273 * This method is used for PLLs, which don't support the on-the-fly dividers
274 * adjustment. So the corresponding clocks are supposed to be gated first.
275 */
276static int ccu_pll_set_rate_norst(struct clk_hw *hw, unsigned long rate,
277 unsigned long parent_rate)
278{
279 struct ccu_pll *pll = to_ccu_pll(hw);
280 unsigned long nr, nf, od;
281 unsigned long flags;
282 u32 mask, val;
283
284 ccu_pll_calc_factors(rate, parent_rate, nr: &nr, nf: &nf, od: &od);
285
286 /*
287 * Disable PLL if it was enabled by default or left enabled by the
288 * system bootloader.
289 */
290 mask = CCU_PLL_CTL_CLKR_MASK | CCU_PLL_CTL_CLKF_MASK |
291 CCU_PLL_CTL_CLKOD_MASK | CCU_PLL_CTL_EN;
292 val = FIELD_PREP(CCU_PLL_CTL_CLKR_MASK, nr - 1) |
293 FIELD_PREP(CCU_PLL_CTL_CLKF_MASK, nf - 1) |
294 FIELD_PREP(CCU_PLL_CTL_CLKOD_MASK, od - 1);
295
296 spin_lock_irqsave(&pll->lock, flags);
297 regmap_update_bits(map: pll->sys_regs, reg: pll->reg_ctl, mask, val);
298 spin_unlock_irqrestore(lock: &pll->lock, flags);
299
300 return 0;
301}
302
303#ifdef CONFIG_DEBUG_FS
304
305struct ccu_pll_dbgfs_bit {
306 struct ccu_pll *pll;
307 const char *name;
308 unsigned int reg;
309 u32 mask;
310};
311
312struct ccu_pll_dbgfs_fld {
313 struct ccu_pll *pll;
314 const char *name;
315 unsigned int reg;
316 unsigned int lsb;
317 u32 mask;
318 u32 min;
319 u32 max;
320};
321
322#define CCU_PLL_DBGFS_BIT_ATTR(_name, _reg, _mask) \
323 { \
324 .name = _name, \
325 .reg = _reg, \
326 .mask = _mask \
327 }
328
329#define CCU_PLL_DBGFS_FLD_ATTR(_name, _reg, _lsb, _mask, _min, _max) \
330 { \
331 .name = _name, \
332 .reg = _reg, \
333 .lsb = _lsb, \
334 .mask = _mask, \
335 .min = _min, \
336 .max = _max \
337 }
338
339static const struct ccu_pll_dbgfs_bit ccu_pll_bits[] = {
340 CCU_PLL_DBGFS_BIT_ATTR("pll_en", CCU_PLL_CTL, CCU_PLL_CTL_EN),
341 CCU_PLL_DBGFS_BIT_ATTR("pll_rst", CCU_PLL_CTL, CCU_PLL_CTL_RST),
342 CCU_PLL_DBGFS_BIT_ATTR("pll_bypass", CCU_PLL_CTL, CCU_PLL_CTL_BYPASS),
343 CCU_PLL_DBGFS_BIT_ATTR("pll_lock", CCU_PLL_CTL, CCU_PLL_CTL_LOCK)
344};
345
346#define CCU_PLL_DBGFS_BIT_NUM ARRAY_SIZE(ccu_pll_bits)
347
348static const struct ccu_pll_dbgfs_fld ccu_pll_flds[] = {
349 CCU_PLL_DBGFS_FLD_ATTR("pll_nr", CCU_PLL_CTL, CCU_PLL_CTL_CLKR_FLD,
350 CCU_PLL_CTL_CLKR_MASK, 1, CCU_PLL_NR_MAX),
351 CCU_PLL_DBGFS_FLD_ATTR("pll_nf", CCU_PLL_CTL, CCU_PLL_CTL_CLKF_FLD,
352 CCU_PLL_CTL_CLKF_MASK, 1, CCU_PLL_NF_MAX),
353 CCU_PLL_DBGFS_FLD_ATTR("pll_od", CCU_PLL_CTL, CCU_PLL_CTL_CLKOD_FLD,
354 CCU_PLL_CTL_CLKOD_MASK, 1, CCU_PLL_OD_MAX),
355 CCU_PLL_DBGFS_FLD_ATTR("pll_nb", CCU_PLL_CTL1, CCU_PLL_CTL1_BWADJ_FLD,
356 CCU_PLL_CTL1_BWADJ_MASK, 1, CCU_PLL_NB_MAX)
357};
358
359#define CCU_PLL_DBGFS_FLD_NUM ARRAY_SIZE(ccu_pll_flds)
360
361/*
362 * It can be dangerous to change the PLL settings behind clock framework back,
363 * therefore we don't provide any kernel config based compile time option for
364 * this feature to enable.
365 */
366#undef CCU_PLL_ALLOW_WRITE_DEBUGFS
367#ifdef CCU_PLL_ALLOW_WRITE_DEBUGFS
368
369static int ccu_pll_dbgfs_bit_set(void *priv, u64 val)
370{
371 const struct ccu_pll_dbgfs_bit *bit = priv;
372 struct ccu_pll *pll = bit->pll;
373 unsigned long flags;
374
375 spin_lock_irqsave(&pll->lock, flags);
376 regmap_update_bits(pll->sys_regs, pll->reg_ctl + bit->reg,
377 bit->mask, val ? bit->mask : 0);
378 spin_unlock_irqrestore(&pll->lock, flags);
379
380 return 0;
381}
382
383static int ccu_pll_dbgfs_fld_set(void *priv, u64 val)
384{
385 struct ccu_pll_dbgfs_fld *fld = priv;
386 struct ccu_pll *pll = fld->pll;
387 unsigned long flags;
388 u32 data;
389
390 val = clamp_t(u64, val, fld->min, fld->max);
391 data = ((val - 1) << fld->lsb) & fld->mask;
392
393 spin_lock_irqsave(&pll->lock, flags);
394 regmap_update_bits(pll->sys_regs, pll->reg_ctl + fld->reg, fld->mask,
395 data);
396 spin_unlock_irqrestore(&pll->lock, flags);
397
398 return 0;
399}
400
401#define ccu_pll_dbgfs_mode 0644
402
403#else /* !CCU_PLL_ALLOW_WRITE_DEBUGFS */
404
405#define ccu_pll_dbgfs_bit_set NULL
406#define ccu_pll_dbgfs_fld_set NULL
407#define ccu_pll_dbgfs_mode 0444
408
409#endif /* !CCU_PLL_ALLOW_WRITE_DEBUGFS */
410
411static int ccu_pll_dbgfs_bit_get(void *priv, u64 *val)
412{
413 struct ccu_pll_dbgfs_bit *bit = priv;
414 struct ccu_pll *pll = bit->pll;
415 u32 data = 0;
416
417 regmap_read(map: pll->sys_regs, reg: pll->reg_ctl + bit->reg, val: &data);
418 *val = !!(data & bit->mask);
419
420 return 0;
421}
422DEFINE_DEBUGFS_ATTRIBUTE(ccu_pll_dbgfs_bit_fops,
423 ccu_pll_dbgfs_bit_get, ccu_pll_dbgfs_bit_set, "%llu\n");
424
425static int ccu_pll_dbgfs_fld_get(void *priv, u64 *val)
426{
427 struct ccu_pll_dbgfs_fld *fld = priv;
428 struct ccu_pll *pll = fld->pll;
429 u32 data = 0;
430
431 regmap_read(map: pll->sys_regs, reg: pll->reg_ctl + fld->reg, val: &data);
432 *val = ((data & fld->mask) >> fld->lsb) + 1;
433
434 return 0;
435}
436DEFINE_DEBUGFS_ATTRIBUTE(ccu_pll_dbgfs_fld_fops,
437 ccu_pll_dbgfs_fld_get, ccu_pll_dbgfs_fld_set, "%llu\n");
438
439static void ccu_pll_debug_init(struct clk_hw *hw, struct dentry *dentry)
440{
441 struct ccu_pll *pll = to_ccu_pll(hw);
442 struct ccu_pll_dbgfs_bit *bits;
443 struct ccu_pll_dbgfs_fld *flds;
444 int idx;
445
446 bits = kcalloc(CCU_PLL_DBGFS_BIT_NUM, size: sizeof(*bits), GFP_KERNEL);
447 if (!bits)
448 return;
449
450 for (idx = 0; idx < CCU_PLL_DBGFS_BIT_NUM; ++idx) {
451 bits[idx] = ccu_pll_bits[idx];
452 bits[idx].pll = pll;
453
454 debugfs_create_file_unsafe(name: bits[idx].name, ccu_pll_dbgfs_mode,
455 parent: dentry, data: &bits[idx],
456 fops: &ccu_pll_dbgfs_bit_fops);
457 }
458
459 flds = kcalloc(CCU_PLL_DBGFS_FLD_NUM, size: sizeof(*flds), GFP_KERNEL);
460 if (!flds)
461 return;
462
463 for (idx = 0; idx < CCU_PLL_DBGFS_FLD_NUM; ++idx) {
464 flds[idx] = ccu_pll_flds[idx];
465 flds[idx].pll = pll;
466
467 debugfs_create_file_unsafe(name: flds[idx].name, ccu_pll_dbgfs_mode,
468 parent: dentry, data: &flds[idx],
469 fops: &ccu_pll_dbgfs_fld_fops);
470 }
471}
472
473#else /* !CONFIG_DEBUG_FS */
474
475#define ccu_pll_debug_init NULL
476
477#endif /* !CONFIG_DEBUG_FS */
478
479static const struct clk_ops ccu_pll_gate_to_set_ops = {
480 .enable = ccu_pll_enable,
481 .disable = ccu_pll_disable,
482 .is_enabled = ccu_pll_is_enabled,
483 .recalc_rate = ccu_pll_recalc_rate,
484 .round_rate = ccu_pll_round_rate,
485 .set_rate = ccu_pll_set_rate_norst,
486 .debug_init = ccu_pll_debug_init
487};
488
489static const struct clk_ops ccu_pll_straight_set_ops = {
490 .enable = ccu_pll_enable,
491 .disable = ccu_pll_disable,
492 .is_enabled = ccu_pll_is_enabled,
493 .recalc_rate = ccu_pll_recalc_rate,
494 .round_rate = ccu_pll_round_rate,
495 .set_rate = ccu_pll_set_rate_reset,
496 .debug_init = ccu_pll_debug_init
497};
498
499struct ccu_pll *ccu_pll_hw_register(const struct ccu_pll_init_data *pll_init)
500{
501 struct clk_parent_data parent_data = { };
502 struct clk_init_data hw_init = { };
503 struct ccu_pll *pll;
504 int ret;
505
506 if (!pll_init)
507 return ERR_PTR(error: -EINVAL);
508
509 pll = kzalloc(size: sizeof(*pll), GFP_KERNEL);
510 if (!pll)
511 return ERR_PTR(error: -ENOMEM);
512
513 /*
514 * Note since Baikal-T1 System Controller registers are MMIO-backed
515 * we won't check the regmap IO operations return status, because it
516 * must be zero anyway.
517 */
518 pll->hw.init = &hw_init;
519 pll->reg_ctl = pll_init->base + CCU_PLL_CTL;
520 pll->reg_ctl1 = pll_init->base + CCU_PLL_CTL1;
521 pll->sys_regs = pll_init->sys_regs;
522 pll->id = pll_init->id;
523 spin_lock_init(&pll->lock);
524
525 hw_init.name = pll_init->name;
526 hw_init.flags = pll_init->flags;
527
528 if (hw_init.flags & CLK_SET_RATE_GATE)
529 hw_init.ops = &ccu_pll_gate_to_set_ops;
530 else
531 hw_init.ops = &ccu_pll_straight_set_ops;
532
533 if (!pll_init->parent_name) {
534 ret = -EINVAL;
535 goto err_free_pll;
536 }
537 parent_data.fw_name = pll_init->parent_name;
538 hw_init.parent_data = &parent_data;
539 hw_init.num_parents = 1;
540
541 ret = of_clk_hw_register(node: pll_init->np, hw: &pll->hw);
542 if (ret)
543 goto err_free_pll;
544
545 return pll;
546
547err_free_pll:
548 kfree(objp: pll);
549
550 return ERR_PTR(error: ret);
551}
552
553void ccu_pll_hw_unregister(struct ccu_pll *pll)
554{
555 clk_hw_unregister(hw: &pll->hw);
556
557 kfree(objp: pll);
558}
559

source code of linux/drivers/clk/baikal-t1/ccu-pll.c