xref: /openbmc/linux/drivers/clk/at91/clk-pll.c (revision 34fa67e7) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  Copyright (C) 2013 Boris BREZILLON <b.brezillon@overkiz.com>
4  */
5 
6 #include <linux/clk-provider.h>
7 #include <linux/clkdev.h>
8 #include <linux/clk/at91_pmc.h>
9 #include <linux/of.h>
10 #include <linux/mfd/syscon.h>
11 #include <linux/regmap.h>
12 
13 #include "pmc.h"
14 
15 #define PLL_STATUS_MASK(id)	(1 << (1 + (id)))
16 #define PLL_REG(id)		(AT91_CKGR_PLLAR + ((id) * 4))
17 #define PLL_DIV_MASK		0xff
18 #define PLL_DIV_MAX		PLL_DIV_MASK
19 #define PLL_DIV(reg)		((reg) & PLL_DIV_MASK)
20 #define PLL_MUL(reg, layout)	(((reg) >> (layout)->mul_shift) & \
21 				 (layout)->mul_mask)
22 #define PLL_MUL_MIN		2
23 #define PLL_MUL_MASK(layout)	((layout)->mul_mask)
24 #define PLL_MUL_MAX(layout)	(PLL_MUL_MASK(layout) + 1)
25 #define PLL_ICPR_SHIFT(id)	((id) * 16)
26 #define PLL_ICPR_MASK(id)	(0xffff << PLL_ICPR_SHIFT(id))
27 #define PLL_MAX_COUNT		0x3f
28 #define PLL_COUNT_SHIFT		8
29 #define PLL_OUT_SHIFT		14
30 #define PLL_MAX_ID		1
31 
32 #define to_clk_pll(hw) container_of(hw, struct clk_pll, hw)
33 
34 struct clk_pll {
35 	struct clk_hw hw;
36 	struct regmap *regmap;
37 	u8 id;
38 	u8 div;
39 	u8 range;
40 	u16 mul;
41 	const struct clk_pll_layout *layout;
42 	const struct clk_pll_characteristics *characteristics;
43 	struct at91_clk_pms pms;
44 };
45 
46 static inline bool clk_pll_ready(struct regmap *regmap, int id)
47 {
48 	unsigned int status;
49 
50 	regmap_read(regmap, AT91_PMC_SR, &status);
51 
52 	return status & PLL_STATUS_MASK(id) ? 1 : 0;
53 }
54 
55 static int clk_pll_prepare(struct clk_hw *hw)
56 {
57 	struct clk_pll *pll = to_clk_pll(hw);
58 	struct regmap *regmap = pll->regmap;
59 	const struct clk_pll_layout *layout = pll->layout;
60 	const struct clk_pll_characteristics *characteristics =
61 							pll->characteristics;
62 	u8 id = pll->id;
63 	u32 mask = PLL_STATUS_MASK(id);
64 	int offset = PLL_REG(id);
65 	u8 out = 0;
66 	unsigned int pllr;
67 	unsigned int status;
68 	u8 div;
69 	u16 mul;
70 
71 	regmap_read(regmap, offset, &pllr);
72 	div = PLL_DIV(pllr);
73 	mul = PLL_MUL(pllr, layout);
74 
75 	regmap_read(regmap, AT91_PMC_SR, &status);
76 	if ((status & mask) &&
77 	    (div == pll->div && mul == pll->mul))
78 		return 0;
79 
80 	if (characteristics->out)
81 		out = characteristics->out[pll->range];
82 
83 	if (characteristics->icpll)
84 		regmap_update_bits(regmap, AT91_PMC_PLLICPR, PLL_ICPR_MASK(id),
85 			characteristics->icpll[pll->range] << PLL_ICPR_SHIFT(id));
86 
87 	regmap_update_bits(regmap, offset, layout->pllr_mask,
88 			pll->div | (PLL_MAX_COUNT << PLL_COUNT_SHIFT) |
89 			(out << PLL_OUT_SHIFT) |
90 			((pll->mul & layout->mul_mask) << layout->mul_shift));
91 
92 	while (!clk_pll_ready(regmap, pll->id))
93 		cpu_relax();
94 
95 	return 0;
96 }
97 
98 static int clk_pll_is_prepared(struct clk_hw *hw)
99 {
100 	struct clk_pll *pll = to_clk_pll(hw);
101 
102 	return clk_pll_ready(pll->regmap, pll->id);
103 }
104 
105 static void clk_pll_unprepare(struct clk_hw *hw)
106 {
107 	struct clk_pll *pll = to_clk_pll(hw);
108 	unsigned int mask = pll->layout->pllr_mask;
109 
110 	regmap_update_bits(pll->regmap, PLL_REG(pll->id), mask, ~mask);
111 }
112 
113 static unsigned long clk_pll_recalc_rate(struct clk_hw *hw,
114 					 unsigned long parent_rate)
115 {
116 	struct clk_pll *pll = to_clk_pll(hw);
117 
118 	if (!pll->div || !pll->mul)
119 		return 0;
120 
121 	return (parent_rate / pll->div) * (pll->mul + 1);
122 }
123 
124 static long clk_pll_get_best_div_mul(struct clk_pll *pll, unsigned long rate,
125 				     unsigned long parent_rate,
126 				     u32 *div, u32 *mul,
127 				     u32 *index) {
128 	const struct clk_pll_layout *layout = pll->layout;
129 	const struct clk_pll_characteristics *characteristics =
130 							pll->characteristics;
131 	unsigned long bestremainder = ULONG_MAX;
132 	unsigned long maxdiv, mindiv, tmpdiv;
133 	long bestrate = -ERANGE;
134 	unsigned long bestdiv;
135 	unsigned long bestmul;
136 	int i = 0;
137 
138 	/* Check if parent_rate is a valid input rate */
139 	if (parent_rate < characteristics->input.min)
140 		return -ERANGE;
141 
142 	/*
143 	 * Calculate minimum divider based on the minimum multiplier, the
144 	 * parent_rate and the requested rate.
145 	 * Should always be 2 according to the input and output characteristics
146 	 * of the PLL blocks.
147 	 */
148 	mindiv = (parent_rate * PLL_MUL_MIN) / rate;
149 	if (!mindiv)
150 		mindiv = 1;
151 
152 	if (parent_rate > characteristics->input.max) {
153 		tmpdiv = DIV_ROUND_UP(parent_rate, characteristics->input.max);
154 		if (tmpdiv > PLL_DIV_MAX)
155 			return -ERANGE;
156 
157 		if (tmpdiv > mindiv)
158 			mindiv = tmpdiv;
159 	}
160 
161 	/*
162 	 * Calculate the maximum divider which is limited by PLL register
163 	 * layout (limited by the MUL or DIV field size).
164 	 */
165 	maxdiv = DIV_ROUND_UP(parent_rate * PLL_MUL_MAX(layout), rate);
166 	if (maxdiv > PLL_DIV_MAX)
167 		maxdiv = PLL_DIV_MAX;
168 
169 	/*
170 	 * Iterate over the acceptable divider values to find the best
171 	 * divider/multiplier pair (the one that generates the closest
172 	 * rate to the requested one).
173 	 */
174 	for (tmpdiv = mindiv; tmpdiv <= maxdiv; tmpdiv++) {
175 		unsigned long remainder;
176 		unsigned long tmprate;
177 		unsigned long tmpmul;
178 
179 		/*
180 		 * Calculate the multiplier associated with the current
181 		 * divider that provide the closest rate to the requested one.
182 		 */
183 		tmpmul = DIV_ROUND_CLOSEST(rate, parent_rate / tmpdiv);
184 		tmprate = (parent_rate / tmpdiv) * tmpmul;
185 		if (tmprate > rate)
186 			remainder = tmprate - rate;
187 		else
188 			remainder = rate - tmprate;
189 
190 		/*
191 		 * Compare the remainder with the best remainder found until
192 		 * now and elect a new best multiplier/divider pair if the
193 		 * current remainder is smaller than the best one.
194 		 */
195 		if (remainder < bestremainder) {
196 			bestremainder = remainder;
197 			bestdiv = tmpdiv;
198 			bestmul = tmpmul;
199 			bestrate = tmprate;
200 		}
201 
202 		/*
203 		 * We've found a perfect match!
204 		 * Stop searching now and use this multiplier/divider pair.
205 		 */
206 		if (!remainder)
207 			break;
208 	}
209 
210 	/* We haven't found any multiplier/divider pair => return -ERANGE */
211 	if (bestrate < 0)
212 		return bestrate;
213 
214 	/* Check if bestrate is a valid output rate  */
215 	for (i = 0; i < characteristics->num_output; i++) {
216 		if (bestrate >= characteristics->output[i].min &&
217 		    bestrate <= characteristics->output[i].max)
218 			break;
219 	}
220 
221 	if (i >= characteristics->num_output)
222 		return -ERANGE;
223 
224 	if (div)
225 		*div = bestdiv;
226 	if (mul)
227 		*mul = bestmul - 1;
228 	if (index)
229 		*index = i;
230 
231 	return bestrate;
232 }
233 
234 static long clk_pll_round_rate(struct clk_hw *hw, unsigned long rate,
235 					unsigned long *parent_rate)
236 {
237 	struct clk_pll *pll = to_clk_pll(hw);
238 
239 	return clk_pll_get_best_div_mul(pll, rate, *parent_rate,
240 					NULL, NULL, NULL);
241 }
242 
243 static int clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
244 			    unsigned long parent_rate)
245 {
246 	struct clk_pll *pll = to_clk_pll(hw);
247 	long ret;
248 	u32 div;
249 	u32 mul;
250 	u32 index;
251 
252 	ret = clk_pll_get_best_div_mul(pll, rate, parent_rate,
253 				       &div, &mul, &index);
254 	if (ret < 0)
255 		return ret;
256 
257 	pll->range = index;
258 	pll->div = div;
259 	pll->mul = mul;
260 
261 	return 0;
262 }
263 
264 static int clk_pll_save_context(struct clk_hw *hw)
265 {
266 	struct clk_pll *pll = to_clk_pll(hw);
267 	struct clk_hw *parent_hw = clk_hw_get_parent(hw);
268 
269 	pll->pms.parent_rate = clk_hw_get_rate(parent_hw);
270 	pll->pms.rate = clk_pll_recalc_rate(&pll->hw, pll->pms.parent_rate);
271 	pll->pms.status = clk_pll_ready(pll->regmap, PLL_REG(pll->id));
272 
273 	return 0;
274 }
275 
276 static void clk_pll_restore_context(struct clk_hw *hw)
277 {
278 	struct clk_pll *pll = to_clk_pll(hw);
279 	unsigned long calc_rate;
280 	unsigned int pllr, pllr_out, pllr_count;
281 	u8 out = 0;
282 
283 	if (pll->characteristics->out)
284 		out = pll->characteristics->out[pll->range];
285 
286 	regmap_read(pll->regmap, PLL_REG(pll->id), &pllr);
287 
288 	calc_rate = (pll->pms.parent_rate / PLL_DIV(pllr)) *
289 		     (PLL_MUL(pllr, pll->layout) + 1);
290 	pllr_count = (pllr >> PLL_COUNT_SHIFT) & PLL_MAX_COUNT;
291 	pllr_out = (pllr >> PLL_OUT_SHIFT) & out;
292 
293 	if (pll->pms.rate != calc_rate ||
294 	    pll->pms.status != clk_pll_ready(pll->regmap, PLL_REG(pll->id)) ||
295 	    pllr_count != PLL_MAX_COUNT ||
296 	    (out && pllr_out != out))
297 		pr_warn("PLLAR was not configured properly by firmware\n");
298 }
299 
300 static const struct clk_ops pll_ops = {
301 	.prepare = clk_pll_prepare,
302 	.unprepare = clk_pll_unprepare,
303 	.is_prepared = clk_pll_is_prepared,
304 	.recalc_rate = clk_pll_recalc_rate,
305 	.round_rate = clk_pll_round_rate,
306 	.set_rate = clk_pll_set_rate,
307 	.save_context = clk_pll_save_context,
308 	.restore_context = clk_pll_restore_context,
309 };
310 
311 struct clk_hw * __init
312 at91_clk_register_pll(struct regmap *regmap, const char *name,
313 		      const char *parent_name, u8 id,
314 		      const struct clk_pll_layout *layout,
315 		      const struct clk_pll_characteristics *characteristics)
316 {
317 	struct clk_pll *pll;
318 	struct clk_hw *hw;
319 	struct clk_init_data init;
320 	int offset = PLL_REG(id);
321 	unsigned int pllr;
322 	int ret;
323 
324 	if (id > PLL_MAX_ID)
325 		return ERR_PTR(-EINVAL);
326 
327 	pll = kzalloc(sizeof(*pll), GFP_KERNEL);
328 	if (!pll)
329 		return ERR_PTR(-ENOMEM);
330 
331 	init.name = name;
332 	init.ops = &pll_ops;
333 	init.parent_names = &parent_name;
334 	init.num_parents = 1;
335 	init.flags = CLK_SET_RATE_GATE;
336 
337 	pll->id = id;
338 	pll->hw.init = &init;
339 	pll->layout = layout;
340 	pll->characteristics = characteristics;
341 	pll->regmap = regmap;
342 	regmap_read(regmap, offset, &pllr);
343 	pll->div = PLL_DIV(pllr);
344 	pll->mul = PLL_MUL(pllr, layout);
345 
346 	hw = &pll->hw;
347 	ret = clk_hw_register(NULL, &pll->hw);
348 	if (ret) {
349 		kfree(pll);
350 		hw = ERR_PTR(ret);
351 	}
352 
353 	return hw;
354 }
355 
356 
357 const struct clk_pll_layout at91rm9200_pll_layout = {
358 	.pllr_mask = 0x7FFFFFF,
359 	.mul_shift = 16,
360 	.mul_mask = 0x7FF,
361 };
362 
363 const struct clk_pll_layout at91sam9g45_pll_layout = {
364 	.pllr_mask = 0xFFFFFF,
365 	.mul_shift = 16,
366 	.mul_mask = 0xFF,
367 };
368 
369 const struct clk_pll_layout at91sam9g20_pllb_layout = {
370 	.pllr_mask = 0x3FFFFF,
371 	.mul_shift = 16,
372 	.mul_mask = 0x3F,
373 };
374 
375 const struct clk_pll_layout sama5d3_pll_layout = {
376 	.pllr_mask = 0x1FFFFFF,
377 	.mul_shift = 18,
378 	.mul_mask = 0x7F,
379 };
380