summaryrefslogtreecommitdiffstats
path: root/drivers/media/i2c/smiapp-pll.c
blob: 771db56332b2cad211d948950fabce15332156fb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
/*
 * drivers/media/i2c/smiapp-pll.c
 *
 * Generic driver for SMIA/SMIA++ compliant camera modules
 *
 * Copyright (C) 2011--2012 Nokia Corporation
 * Contact: Sakari Ailus <sakari.ailus@iki.fi>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 */

#include <linux/device.h>
#include <linux/gcd.h>
#include <linux/lcm.h>
#include <linux/module.h>

#include "smiapp-pll.h"

/* Return an even number or one. */
static inline uint32_t clk_div_even(uint32_t a)
{
	return max_t(uint32_t, 1, a & ~1);
}

/* Return an even number or one. */
static inline uint32_t clk_div_even_up(uint32_t a)
{
	if (a == 1)
		return 1;
	return (a + 1) & ~1;
}

static inline uint32_t is_one_or_even(uint32_t a)
{
	if (a == 1)
		return 1;
	if (a & 1)
		return 0;

	return 1;
}

static int bounds_check(struct device *dev, uint32_t val,
			uint32_t min, uint32_t max, char *str)
{
	if (val >= min && val <= max)
		return 0;

	dev_dbg(dev, "%s out of bounds: %d (%d--%d)\n", str, val, min, max);

	return -EINVAL;
}

static void print_pll(struct device *dev, struct smiapp_pll *pll)
{
	dev_dbg(dev, "pre_pll_clk_div\t%u\n",  pll->pre_pll_clk_div);
	dev_dbg(dev, "pll_multiplier \t%u\n",  pll->pll_multiplier);
	if (!(pll->flags & SMIAPP_PLL_FLAG_NO_OP_CLOCKS)) {
		dev_dbg(dev, "op_sys_clk_div \t%u\n", pll->op.sys_clk_div);
		dev_dbg(dev, "op_pix_clk_div \t%u\n", pll->op.pix_clk_div);
	}
	dev_dbg(dev, "vt_sys_clk_div \t%u\n",  pll->vt.sys_clk_div);
	dev_dbg(dev, "vt_pix_clk_div \t%u\n",  pll->vt.pix_clk_div);

	dev_dbg(dev, "ext_clk_freq_hz \t%u\n", pll->ext_clk_freq_hz);
	dev_dbg(dev, "pll_ip_clk_freq_hz \t%u\n", pll->pll_ip_clk_freq_hz);
	dev_dbg(dev, "pll_op_clk_freq_hz \t%u\n", pll->pll_op_clk_freq_hz);
	if (!(pll->flags & SMIAPP_PLL_FLAG_NO_OP_CLOCKS)) {
		dev_dbg(dev, "op_sys_clk_freq_hz \t%u\n",
			pll->op.sys_clk_freq_hz);
		dev_dbg(dev, "op_pix_clk_freq_hz \t%u\n",
			pll->op.pix_clk_freq_hz);
	}
	dev_dbg(dev, "vt_sys_clk_freq_hz \t%u\n", pll->vt.sys_clk_freq_hz);
	dev_dbg(dev, "vt_pix_clk_freq_hz \t%u\n", pll->vt.pix_clk_freq_hz);
}

static int check_all_bounds(struct device *dev,
			    const struct smiapp_pll_limits *limits,
			    const struct smiapp_pll_branch_limits *op_limits,
			    struct smiapp_pll *pll,
			    struct smiapp_pll_branch *op_pll)
{
	int rval;

	rval = bounds_check(dev, pll->pll_ip_clk_freq_hz,
			    limits->min_pll_ip_freq_hz,
			    limits->max_pll_ip_freq_hz,
			    "pll_ip_clk_freq_hz");
	if (!rval)
		rval = bounds_check(
			dev, pll->pll_multiplier,
			limits->min_pll_multiplier, limits->max_pll_multiplier,
			"pll_multiplier");
	if (!rval)
		rval = bounds_check(
			dev, pll->pll_op_clk_freq_hz,
			limits->min_pll_op_freq_hz, limits->max_pll_op_freq_hz,
			"pll_op_clk_freq_hz");
	if (!rval)
		rval = bounds_check(
			dev, op_pll->sys_clk_div,
			op_limits->min_sys_clk_div, op_limits->max_sys_clk_div,
			"op_sys_clk_div");
	if (!rval)
		rval = bounds_check(
			dev, op_pll->sys_clk_freq_hz,
			op_limits->min_sys_clk_freq_hz,
			op_limits->max_sys_clk_freq_hz,
			"op_sys_clk_freq_hz");
	if (!rval)
		rval = bounds_check(
			dev, op_pll->pix_clk_freq_hz,
			op_limits->min_pix_clk_freq_hz,
			op_limits->max_pix_clk_freq_hz,
			"op_pix_clk_freq_hz");

	/*
	 * If there are no OP clocks, the VT clocks are contained in
	 * the OP clock struct.
	 */
	if (pll->flags & SMIAPP_PLL_FLAG_NO_OP_CLOCKS)
		return rval;

	if (!rval)
		rval = bounds_check(
			dev, pll->vt.sys_clk_freq_hz,
			limits->vt.min_sys_clk_freq_hz,
			limits->vt.max_sys_clk_freq_hz,
			"vt_sys_clk_freq_hz");
	if (!rval)
		rval = bounds_check(
			dev, pll->vt.pix_clk_freq_hz,
			limits->vt.min_pix_clk_freq_hz,
			limits->vt.max_pix_clk_freq_hz,
			"vt_pix_clk_freq_hz");

	return rval;
}

/*
 * Heuristically guess the PLL tree for a given common multiplier and
 * divisor. Begin with the operational timing and continue to video
 * timing once operational timing has been verified.
 *
 * @mul is the PLL multiplier and @div is the common divisor
 * (pre_pll_clk_div and op_sys_clk_div combined). The final PLL
 * multiplier will be a multiple of @mul.
 *
 * @return Zero on success, error code on error.
 */
static int __smiapp_pll_calculate(
	struct device *dev, const struct smiapp_pll_limits *limits,
	const struct smiapp_pll_branch_limits *op_limits,
	struct smiapp_pll *pll, struct smiapp_pll_branch *op_pll, uint32_t mul,
	uint32_t div, uint32_t lane_op_clock_ratio)
{
	uint32_t sys_div;
	uint32_t best_pix_div = INT_MAX >> 1;
	uint32_t vt_op_binning_div;
	/*
	 * Higher multipliers (and divisors) are often required than
	 * necessitated by the external clock and the output clocks.
	 * There are limits for all values in the clock tree. These
	 * are the minimum and maximum multiplier for mul.
	 */
	uint32_t more_mul_min, more_mul_max;
	uint32_t more_mul_factor;
	uint32_t min_vt_div, max_vt_div, vt_div;
	uint32_t min_sys_div, max_sys_div;
	unsigned int i;

	/*
	 * Get pre_pll_clk_div so that our pll_op_clk_freq_hz won't be
	 * too high.
	 */
	dev_dbg(dev, "pre_pll_clk_div %u\n", pll->pre_pll_clk_div);

	/* Don't go above max pll multiplier. */
	more_mul_max = limits->max_pll_multiplier / mul;
	dev_dbg(dev, "more_mul_max: max_pll_multiplier check: %u\n",
		more_mul_max);
	/* Don't go above max pll op frequency. */
	more_mul_max =
		min_t(uint32_t,
		      more_mul_max,
		      limits->max_pll_op_freq_hz
		      / (pll->ext_clk_freq_hz / pll->pre_pll_clk_div * mul));
	dev_dbg(dev, "more_mul_max: max_pll_op_freq_hz check: %u\n",
		more_mul_max);
	/* Don't go above the division capability of op sys clock divider. */
	more_mul_max = min(more_mul_max,
			   op_limits->max_sys_clk_div * pll->pre_pll_clk_div
			   / div);
	dev_dbg(dev, "more_mul_max: max_op_sys_clk_div check: %u\n",
		more_mul_max);
	/* Ensure we won't go above min_pll_multiplier. */
	more_mul_max = min(more_mul_max,
			   DIV_ROUND_UP(limits->max_pll_multiplier, mul));
	dev_dbg(dev, "more_mul_max: min_pll_multiplier check: %u\n",
		more_mul_max);

	/* Ensure we won't go below min_pll_op_freq_hz. */
	more_mul_min = DIV_ROUND_UP(limits->min_pll_op_freq_hz,
				    pll->ext_clk_freq_hz / pll->pre_pll_clk_div
				    * mul);
	dev_dbg(dev, "more_mul_min: min_pll_op_freq_hz check: %u\n",
		more_mul_min);
	/* Ensure we won't go below min_pll_multiplier. */
	more_mul_min = max(more_mul_min,
			   DIV_ROUND_UP(limits->min_pll_multiplier, mul));
	dev_dbg(dev, "more_mul_min: min_pll_multiplier check: %u\n",
		more_mul_min);

	if (more_mul_min > more_mul_max) {
		dev_dbg(dev,
			"unable to compute more_mul_min and more_mul_max\n");
		return -EINVAL;
	}

	more_mul_factor = lcm(div, pll->pre_pll_clk_div) / div;
	dev_dbg(dev, "more_mul_factor: %u\n", more_mul_factor);
	more_mul_factor = lcm(more_mul_factor, op_limits->min_sys_clk_div);
	dev_dbg(dev, "more_mul_factor: min_op_sys_clk_div: %d\n",
		more_mul_factor);
	i = roundup(more_mul_min, more_mul_factor);
	if (!is_one_or_even(i))
		i <<= 1;

	dev_dbg(dev, "final more_mul: %u\n", i);
	if (i > more_mul_max) {
		dev_dbg(dev, "final more_mul is bad, max %u\n", more_mul_max);
		return -EINVAL;
	}

	pll->pll_multiplier = mul * i;
	op_pll->sys_clk_div = div * i / pll->pre_pll_clk_div;
	dev_dbg(dev, "op_sys_clk_div: %u\n", op_pll->sys_clk_div);

	pll->pll_ip_clk_freq_hz = pll->ext_clk_freq_hz
		/ pll->pre_pll_clk_div;

	pll->pll_op_clk_freq_hz = pll->pll_ip_clk_freq_hz
		* pll->pll_multiplier;

	/* Derive pll_op_clk_freq_hz. */
	op_pll->sys_clk_freq_hz =
		pll->pll_op_clk_freq_hz / op_pll->sys_clk_div;

	op_pll->pix_clk_div = pll->bits_per_pixel;
	dev_dbg(dev, "op_pix_clk_div: %u\n", op_pll->pix_clk_div);

	op_pll->pix_clk_freq_hz =
		op_pll->sys_clk_freq_hz / op_pll->pix_clk_div;

	if (pll->flags & SMIAPP_PLL_FLAG_NO_OP_CLOCKS) {
		/* No OP clocks --- VT clocks are used instead. */
		goto out_skip_vt_calc;
	}

	/*
	 * Some sensors perform analogue binning and some do this
	 * digitally. The ones doing this digitally can be roughly be
	 * found out using this formula. The ones doing this digitally
	 * should run at higher clock rate, so smaller divisor is used
	 * on video timing side.
	 */
	if (limits->min_line_length_pck_bin > limits->min_line_length_pck
	    / pll->binning_horizontal)
		vt_op_binning_div = pll->binning_horizontal;
	else
		vt_op_binning_div = 1;
	dev_dbg(dev, "vt_op_binning_div: %u\n", vt_op_binning_div);

	/*
	 * Profile 2 supports vt_pix_clk_div E [4, 10]
	 *
	 * Horizontal binning can be used as a base for difference in
	 * divisors. One must make sure that horizontal blanking is
	 * enough to accommodate the CSI-2 sync codes.
	 *
	 * Take scaling factor into account as well.
	 *
	 * Find absolute limits for the factor of vt divider.
	 */
	dev_dbg(dev, "scale_m: %u\n", pll->scale_m);
	min_vt_div = DIV_ROUND_UP(op_pll->pix_clk_div * op_pll->sys_clk_div
				  * pll->scale_n,
				  lane_op_clock_ratio * vt_op_binning_div
				  * pll->scale_m);

	/* Find smallest and biggest allowed vt divisor. */
	dev_dbg(dev, "min_vt_div: %u\n", min_vt_div);
	min_vt_div = max(min_vt_div,
			 DIV_ROUND_UP(pll->pll_op_clk_freq_hz,
				      limits->vt.max_pix_clk_freq_hz));
	dev_dbg(dev, "min_vt_div: max_vt_pix_clk_freq_hz: %u\n",
		min_vt_div);
	min_vt_div = max_t(uint32_t, min_vt_div,
			   limits->vt.min_pix_clk_div
			   * limits->vt.min_sys_clk_div);
	dev_dbg(dev, "min_vt_div: min_vt_clk_div: %u\n", min_vt_div);

	max_vt_div = limits->vt.max_sys_clk_div * limits->vt.max_pix_clk_div;
	dev_dbg(dev, "max_vt_div: %u\n", max_vt_div);
	max_vt_div = min(max_vt_div,
			 DIV_ROUND_UP(pll->pll_op_clk_freq_hz,
				      limits->vt.min_pix_clk_freq_hz));
	dev_dbg(dev, "max_vt_div: min_vt_pix_clk_freq_hz: %u\n",
		max_vt_div);

	/*
	 * Find limitsits for sys_clk_div. Not all values are possible
	 * with all values of pix_clk_div.
	 */
	min_sys_div = limits->vt.min_sys_clk_div;
	dev_dbg(dev, "min_sys_div: %u\n", min_sys_div);
	min_sys_div = max(min_sys_div,
			  DIV_ROUND_UP(min_vt_div,
				       limits->vt.max_pix_clk_div));
	dev_dbg(dev, "min_sys_div: max_vt_pix_clk_div: %u\n", min_sys_div);
	min_sys_div = max(min_sys_div,
			  pll->pll_op_clk_freq_hz
			  / limits->vt.max_sys_clk_freq_hz);
	dev_dbg(dev, "min_sys_div: max_pll_op_clk_freq_hz: %u\n", min_sys_div);
	min_sys_div = clk_div_even_up(min_sys_div);
	dev_dbg(dev, "min_sys_div: one or even: %u\n", min_sys_div);

	max_sys_div = limits->vt.max_sys_clk_div;
	dev_dbg(dev, "max_sys_div: %u\n", max_sys_div);
	max_sys_div = min(max_sys_div,
			  DIV_ROUND_UP(max_vt_div,
				       limits->vt.min_pix_clk_div));
	dev_dbg(dev, "max_sys_div: min_vt_pix_clk_div: %u\n", max_sys_div);
	max_sys_div = min(max_sys_div,
			  DIV_ROUND_UP(pll->pll_op_clk_freq_hz,
				       limits->vt.min_pix_clk_freq_hz));
	dev_dbg(dev, "max_sys_div: min_vt_pix_clk_freq_hz: %u\n", max_sys_div);

	/*
	 * Find pix_div such that a legal pix_div * sys_div results
	 * into a value which is not smaller than div, the desired
	 * divisor.
	 */
	for (vt_div = min_vt_div; vt_div <= max_vt_div;
	     vt_div += 2 - (vt_div & 1)) {
		for (sys_div = min_sys_div;
		     sys_div <= max_sys_div;
		     sys_div += 2 - (sys_div & 1)) {
			uint16_t pix_div = DIV_ROUND_UP(vt_div, sys_div);

			if (pix_div < limits->vt.min_pix_clk_div
			    || pix_div > limits->vt.max_pix_clk_div) {
				dev_dbg(dev,
					"pix_div %u too small or too big (%u--%u)\n",
					pix_div,
					limits->vt.min_pix_clk_div,
					limits->vt.max_pix_clk_div);
				continue;
			}

			/* Check if this one is better. */
			if (pix_div * sys_div
			    <= roundup(min_vt_div, best_pix_div))
				best_pix_div = pix_div;
		}
		if (best_pix_div < INT_MAX >> 1)
			break;
	}

	pll->vt.sys_clk_div = DIV_ROUND_UP(min_vt_div, best_pix_div);
	pll->vt.pix_clk_div = best_pix_div;

	pll->vt.sys_clk_freq_hz =
		pll->pll_op_clk_freq_hz / pll->vt.sys_clk_div;
	pll->vt.pix_clk_freq_hz =
		pll->vt.sys_clk_freq_hz / pll->vt.pix_clk_div;

out_skip_vt_calc:
	pll->pixel_rate_csi =
		op_pll->pix_clk_freq_hz * lane_op_clock_ratio;
	pll->pixel_rate_pixel_array = pll->vt.pix_clk_freq_hz;

	return check_all_bounds(dev, limits, op_limits, pll, op_pll);
}

int smiapp_pll_calculate(struct device *dev,
			 const struct smiapp_pll_limits *limits,
			 struct smiapp_pll *pll)
{
	const struct smiapp_pll_branch_limits *op_limits = &limits->op;
	struct smiapp_pll_branch *op_pll = &pll->op;
	uint16_t min_pre_pll_clk_div;
	uint16_t max_pre_pll_clk_div;
	uint32_t lane_op_clock_ratio;
	uint32_t mul, div;
	unsigned int i;
	int rval = -EINVAL;

	if (pll->flags & SMIAPP_PLL_FLAG_NO_OP_CLOCKS) {
		/*
		 * If there's no OP PLL at all, use the VT values
		 * instead. The OP values are ignored for the rest of
		 * the PLL calculation.
		 */
		op_limits = &limits->vt;
		op_pll = &pll->vt;
	}

	if (pll->flags & SMIAPP_PLL_FLAG_OP_PIX_CLOCK_PER_LANE)
		lane_op_clock_ratio = pll->csi2.lanes;
	else
		lane_op_clock_ratio = 1;
	dev_dbg(dev, "lane_op_clock_ratio: %u\n", lane_op_clock_ratio);

	dev_dbg(dev, "binning: %ux%u\n", pll->binning_horizontal,
		pll->binning_vertical);

	switch (pll->bus_type) {
	case SMIAPP_PLL_BUS_TYPE_CSI2:
		/* CSI transfers 2 bits per clock per lane; thus times 2 */
		pll->pll_op_clk_freq_hz = pll->link_freq * 2
			* (pll->csi2.lanes / lane_op_clock_ratio);
		break;
	case SMIAPP_PLL_BUS_TYPE_PARALLEL:
		pll->pll_op_clk_freq_hz = pll->link_freq * pll->bits_per_pixel
			/ DIV_ROUND_UP(pll->bits_per_pixel,
				       pll->parallel.bus_width);
		break;
	default:
		return -EINVAL;
	}

	/* Figure out limits for pre-pll divider based on extclk */
	dev_dbg(dev, "min / max pre_pll_clk_div: %u / %u\n",
		limits->min_pre_pll_clk_div, limits->max_pre_pll_clk_div);
	max_pre_pll_clk_div =
		min_t(uint16_t, limits->max_pre_pll_clk_div,
		      clk_div_even(pll->ext_clk_freq_hz /
				   limits->min_pll_ip_freq_hz));
	min_pre_pll_clk_div =
		max_t(uint16_t, limits->min_pre_pll_clk_div,
		      clk_div_even_up(
			      DIV_ROUND_UP(pll->ext_clk_freq_hz,
					   limits->max_pll_ip_freq_hz)));
	dev_dbg(dev, "pre-pll check: min / max pre_pll_clk_div: %u / %u\n",
		min_pre_pll_clk_div, max_pre_pll_clk_div);

	i = gcd(pll->pll_op_clk_freq_hz, pll->ext_clk_freq_hz);
	mul = div_u64(pll->pll_op_clk_freq_hz, i);
	div = pll->ext_clk_freq_hz / i;
	dev_dbg(dev, "mul %u / div %u\n", mul, div);

	min_pre_pll_clk_div =
		max_t(uint16_t, min_pre_pll_clk_div,
		      clk_div_even_up(
			      DIV_ROUND_UP(mul * pll->ext_clk_freq_hz,
					   limits->max_pll_op_freq_hz)));
	dev_dbg(dev, "pll_op check: min / max pre_pll_clk_div: %u / %u\n",
		min_pre_pll_clk_div, max_pre_pll_clk_div);

	for (pll->pre_pll_clk_div = min_pre_pll_clk_div;
	     pll->pre_pll_clk_div <= max_pre_pll_clk_div;
	     pll->pre_pll_clk_div += 2 - (pll->pre_pll_clk_div & 1)) {
		rval = __smiapp_pll_calculate(dev, limits, op_limits, pll,
					      op_pll, mul, div,
					      lane_op_clock_ratio);
		if (rval)
			continue;

		print_pll(dev, pll);
		return 0;
	}

	dev_dbg(dev, "unable to compute pre_pll divisor\n");

	return rval;
}
EXPORT_SYMBOL_GPL(smiapp_pll_calculate);

MODULE_AUTHOR("Sakari Ailus <sakari.ailus@iki.fi>");
MODULE_DESCRIPTION("Generic SMIA/SMIA++ PLL calculator");
MODULE_LICENSE("GPL");