xref: /openbmc/linux/drivers/clk/meson/clk-pll.c (revision 6e2acbfe)
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 *
meson_clk_pll_data(struct clk_regmap * clk)40 meson_clk_pll_data(struct clk_regmap *clk)
41 {
42 	return (struct meson_clk_pll_data *)clk->data;
43 }
44 
__pll_round_closest_mult(struct meson_clk_pll_data * pll)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 
__pll_params_to_rate(unsigned long parent_rate,unsigned int m,unsigned int n,unsigned int frac,struct meson_clk_pll_data * pll)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 
meson_clk_pll_recalc_rate(struct clk_hw * hw,unsigned long parent_rate)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 
__pll_params_with_frac(unsigned long rate,unsigned long parent_rate,unsigned int m,unsigned int n,struct meson_clk_pll_data * pll)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 
meson_clk_pll_is_better(unsigned long rate,unsigned long best,unsigned long now,struct meson_clk_pll_data * pll)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 
meson_clk_get_pll_table_index(unsigned int index,unsigned int * m,unsigned int * n,struct meson_clk_pll_data * pll)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 
meson_clk_get_pll_range_m(unsigned long rate,unsigned long parent_rate,unsigned int n,struct meson_clk_pll_data * pll)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 
meson_clk_get_pll_range_index(unsigned long rate,unsigned long parent_rate,unsigned int index,unsigned int * m,unsigned int * n,struct meson_clk_pll_data * pll)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 
meson_clk_get_pll_get_index(unsigned long rate,unsigned long parent_rate,unsigned int index,unsigned int * m,unsigned int * n,struct meson_clk_pll_data * pll)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 
meson_clk_get_pll_settings(unsigned long rate,unsigned long parent_rate,unsigned int * best_m,unsigned int * best_n,struct meson_clk_pll_data * pll)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 
meson_clk_pll_determine_rate(struct clk_hw * hw,struct clk_rate_request * req)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 
meson_clk_pll_wait_lock(struct clk_hw * hw)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 
meson_clk_pll_init(struct clk_hw * hw)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 		if (MESON_PARM_APPLICABLE(&pll->rst))
299 			meson_parm_write(clk->map, &pll->rst, 1);
300 
301 		regmap_multi_reg_write(clk->map, pll->init_regs,
302 				       pll->init_count);
303 
304 		if (MESON_PARM_APPLICABLE(&pll->rst))
305 			meson_parm_write(clk->map, &pll->rst, 0);
306 	}
307 
308 	return 0;
309 }
310 
meson_clk_pll_is_enabled(struct clk_hw * hw)311 static int meson_clk_pll_is_enabled(struct clk_hw *hw)
312 {
313 	struct clk_regmap *clk = to_clk_regmap(hw);
314 	struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
315 
316 	if (MESON_PARM_APPLICABLE(&pll->rst) &&
317 	    meson_parm_read(clk->map, &pll->rst))
318 		return 0;
319 
320 	if (!meson_parm_read(clk->map, &pll->en) ||
321 	    !meson_parm_read(clk->map, &pll->l))
322 		return 0;
323 
324 	return 1;
325 }
326 
meson_clk_pcie_pll_enable(struct clk_hw * hw)327 static int meson_clk_pcie_pll_enable(struct clk_hw *hw)
328 {
329 	int retries = 10;
330 
331 	do {
332 		meson_clk_pll_init(hw);
333 		if (!meson_clk_pll_wait_lock(hw))
334 			return 0;
335 		pr_info("Retry enabling PCIe PLL clock\n");
336 	} while (--retries);
337 
338 	return -EIO;
339 }
340 
meson_clk_pll_enable(struct clk_hw * hw)341 static int meson_clk_pll_enable(struct clk_hw *hw)
342 {
343 	struct clk_regmap *clk = to_clk_regmap(hw);
344 	struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
345 
346 	/* do nothing if the PLL is already enabled */
347 	if (clk_hw_is_enabled(hw))
348 		return 0;
349 
350 	/* Make sure the pll is in reset */
351 	if (MESON_PARM_APPLICABLE(&pll->rst))
352 		meson_parm_write(clk->map, &pll->rst, 1);
353 
354 	/* Enable the pll */
355 	meson_parm_write(clk->map, &pll->en, 1);
356 
357 	/* Take the pll out reset */
358 	if (MESON_PARM_APPLICABLE(&pll->rst))
359 		meson_parm_write(clk->map, &pll->rst, 0);
360 
361 	/*
362 	 * Compared with the previous SoCs, self-adaption current module
363 	 * is newly added for A1, keep the new power-on sequence to enable the
364 	 * PLL. The sequence is:
365 	 * 1. enable the pll, delay for 10us
366 	 * 2. enable the pll self-adaption current module, delay for 40us
367 	 * 3. enable the lock detect module
368 	 */
369 	if (MESON_PARM_APPLICABLE(&pll->current_en)) {
370 		udelay(10);
371 		meson_parm_write(clk->map, &pll->current_en, 1);
372 		udelay(40);
373 	}
374 
375 	if (MESON_PARM_APPLICABLE(&pll->l_detect)) {
376 		meson_parm_write(clk->map, &pll->l_detect, 1);
377 		meson_parm_write(clk->map, &pll->l_detect, 0);
378 	}
379 
380 	if (meson_clk_pll_wait_lock(hw))
381 		return -EIO;
382 
383 	return 0;
384 }
385 
meson_clk_pll_disable(struct clk_hw * hw)386 static void meson_clk_pll_disable(struct clk_hw *hw)
387 {
388 	struct clk_regmap *clk = to_clk_regmap(hw);
389 	struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
390 
391 	/* Put the pll is in reset */
392 	if (MESON_PARM_APPLICABLE(&pll->rst))
393 		meson_parm_write(clk->map, &pll->rst, 1);
394 
395 	/* Disable the pll */
396 	meson_parm_write(clk->map, &pll->en, 0);
397 
398 	/* Disable PLL internal self-adaption current module */
399 	if (MESON_PARM_APPLICABLE(&pll->current_en))
400 		meson_parm_write(clk->map, &pll->current_en, 0);
401 }
402 
meson_clk_pll_set_rate(struct clk_hw * hw,unsigned long rate,unsigned long parent_rate)403 static int meson_clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
404 				  unsigned long parent_rate)
405 {
406 	struct clk_regmap *clk = to_clk_regmap(hw);
407 	struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
408 	unsigned int enabled, m, n, frac = 0;
409 	unsigned long old_rate;
410 	int ret;
411 
412 	if (parent_rate == 0 || rate == 0)
413 		return -EINVAL;
414 
415 	old_rate = clk_hw_get_rate(hw);
416 
417 	ret = meson_clk_get_pll_settings(rate, parent_rate, &m, &n, pll);
418 	if (ret)
419 		return ret;
420 
421 	enabled = meson_parm_read(clk->map, &pll->en);
422 	if (enabled)
423 		meson_clk_pll_disable(hw);
424 
425 	meson_parm_write(clk->map, &pll->n, n);
426 	meson_parm_write(clk->map, &pll->m, m);
427 
428 	if (MESON_PARM_APPLICABLE(&pll->frac)) {
429 		frac = __pll_params_with_frac(rate, parent_rate, m, n, pll);
430 		meson_parm_write(clk->map, &pll->frac, frac);
431 	}
432 
433 	/* If the pll is stopped, bail out now */
434 	if (!enabled)
435 		return 0;
436 
437 	ret = meson_clk_pll_enable(hw);
438 	if (ret) {
439 		pr_warn("%s: pll did not lock, trying to restore old rate %lu\n",
440 			__func__, old_rate);
441 		/*
442 		 * FIXME: Do we really need/want this HACK ?
443 		 * It looks unsafe. what happens if the clock gets into a
444 		 * broken state and we can't lock back on the old_rate ? Looks
445 		 * like an infinite recursion is possible
446 		 */
447 		meson_clk_pll_set_rate(hw, old_rate, parent_rate);
448 	}
449 
450 	return ret;
451 }
452 
453 /*
454  * The Meson G12A PCIE PLL is fined tuned to deliver a very precise
455  * 100MHz reference clock for the PCIe Analog PHY, and thus requires
456  * a strict register sequence to enable the PLL.
457  * To simplify, re-use the _init() op to enable the PLL and keep
458  * the other ops except set_rate since the rate is fixed.
459  */
460 const struct clk_ops meson_clk_pcie_pll_ops = {
461 	.recalc_rate	= meson_clk_pll_recalc_rate,
462 	.determine_rate	= meson_clk_pll_determine_rate,
463 	.is_enabled	= meson_clk_pll_is_enabled,
464 	.enable		= meson_clk_pcie_pll_enable,
465 	.disable	= meson_clk_pll_disable
466 };
467 EXPORT_SYMBOL_GPL(meson_clk_pcie_pll_ops);
468 
469 const struct clk_ops meson_clk_pll_ops = {
470 	.init		= meson_clk_pll_init,
471 	.recalc_rate	= meson_clk_pll_recalc_rate,
472 	.determine_rate	= meson_clk_pll_determine_rate,
473 	.set_rate	= meson_clk_pll_set_rate,
474 	.is_enabled	= meson_clk_pll_is_enabled,
475 	.enable		= meson_clk_pll_enable,
476 	.disable	= meson_clk_pll_disable
477 };
478 EXPORT_SYMBOL_GPL(meson_clk_pll_ops);
479 
480 const struct clk_ops meson_clk_pll_ro_ops = {
481 	.recalc_rate	= meson_clk_pll_recalc_rate,
482 	.is_enabled	= meson_clk_pll_is_enabled,
483 };
484 EXPORT_SYMBOL_GPL(meson_clk_pll_ro_ops);
485 
486 MODULE_DESCRIPTION("Amlogic PLL driver");
487 MODULE_AUTHOR("Carlo Caione <carlo@endlessm.com>");
488 MODULE_AUTHOR("Jerome Brunet <jbrunet@baylibre.com>");
489 MODULE_LICENSE("GPL v2");
490