2 * drivers/media/i2c/smiapp-pll.c
4 * Generic driver for SMIA/SMIA++ compliant camera modules
6 * Copyright (C) 2011--2012 Nokia Corporation
7 * Contact: Sakari Ailus <sakari.ailus@iki.fi>
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * version 2 as published by the Free Software Foundation.
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
25 #include <linux/gcd.h>
26 #include <linux/lcm.h>
27 #include <linux/module.h>
29 #include "smiapp-pll.h"
31 /* Return an even number or one. */
32 static inline uint32_t clk_div_even(uint32_t a)
34 return max_t(uint32_t, 1, a & ~1);
37 /* Return an even number or one. */
38 static inline uint32_t clk_div_even_up(uint32_t a)
45 static inline uint32_t is_one_or_even(uint32_t a)
55 static int bounds_check(struct device *dev, uint32_t val,
56 uint32_t min, uint32_t max, char *str)
58 if (val >= min && val <= max)
61 dev_dbg(dev, "%s out of bounds: %d (%d--%d)\n", str, val, min, max);
66 static void print_pll(struct device *dev, struct smiapp_pll *pll)
68 dev_dbg(dev, "pre_pll_clk_div\t%u\n", pll->pre_pll_clk_div);
69 dev_dbg(dev, "pll_multiplier \t%u\n", pll->pll_multiplier);
70 if (!(pll->flags & SMIAPP_PLL_FLAG_NO_OP_CLOCKS)) {
71 dev_dbg(dev, "op_sys_clk_div \t%u\n", pll->op.sys_clk_div);
72 dev_dbg(dev, "op_pix_clk_div \t%u\n", pll->op.pix_clk_div);
74 dev_dbg(dev, "vt_sys_clk_div \t%u\n", pll->vt.sys_clk_div);
75 dev_dbg(dev, "vt_pix_clk_div \t%u\n", pll->vt.pix_clk_div);
77 dev_dbg(dev, "ext_clk_freq_hz \t%u\n", pll->ext_clk_freq_hz);
78 dev_dbg(dev, "pll_ip_clk_freq_hz \t%u\n", pll->pll_ip_clk_freq_hz);
79 dev_dbg(dev, "pll_op_clk_freq_hz \t%u\n", pll->pll_op_clk_freq_hz);
80 if (!(pll->flags & SMIAPP_PLL_FLAG_NO_OP_CLOCKS)) {
81 dev_dbg(dev, "op_sys_clk_freq_hz \t%u\n",
82 pll->op.sys_clk_freq_hz);
83 dev_dbg(dev, "op_pix_clk_freq_hz \t%u\n",
84 pll->op.pix_clk_freq_hz);
86 dev_dbg(dev, "vt_sys_clk_freq_hz \t%u\n", pll->vt.sys_clk_freq_hz);
87 dev_dbg(dev, "vt_pix_clk_freq_hz \t%u\n", pll->vt.pix_clk_freq_hz);
90 static int check_all_bounds(struct device *dev,
91 const struct smiapp_pll_limits *limits,
92 const struct smiapp_pll_branch_limits *op_limits,
93 struct smiapp_pll *pll,
94 struct smiapp_pll_branch *op_pll)
98 rval = bounds_check(dev, pll->pll_ip_clk_freq_hz,
99 limits->min_pll_ip_freq_hz,
100 limits->max_pll_ip_freq_hz,
101 "pll_ip_clk_freq_hz");
104 dev, pll->pll_multiplier,
105 limits->min_pll_multiplier, limits->max_pll_multiplier,
109 dev, pll->pll_op_clk_freq_hz,
110 limits->min_pll_op_freq_hz, limits->max_pll_op_freq_hz,
111 "pll_op_clk_freq_hz");
114 dev, op_pll->sys_clk_div,
115 op_limits->min_sys_clk_div, op_limits->max_sys_clk_div,
119 dev, op_pll->sys_clk_freq_hz,
120 op_limits->min_sys_clk_freq_hz,
121 op_limits->max_sys_clk_freq_hz,
122 "op_sys_clk_freq_hz");
125 dev, op_pll->pix_clk_freq_hz,
126 op_limits->min_pix_clk_freq_hz,
127 op_limits->max_pix_clk_freq_hz,
128 "op_pix_clk_freq_hz");
131 * If there are no OP clocks, the VT clocks are contained in
132 * the OP clock struct.
134 if (pll->flags & SMIAPP_PLL_FLAG_NO_OP_CLOCKS)
139 dev, pll->vt.sys_clk_freq_hz,
140 limits->vt.min_sys_clk_freq_hz,
141 limits->vt.max_sys_clk_freq_hz,
142 "vt_sys_clk_freq_hz");
145 dev, pll->vt.pix_clk_freq_hz,
146 limits->vt.min_pix_clk_freq_hz,
147 limits->vt.max_pix_clk_freq_hz,
148 "vt_pix_clk_freq_hz");
154 * Heuristically guess the PLL tree for a given common multiplier and
155 * divisor. Begin with the operational timing and continue to video
156 * timing once operational timing has been verified.
158 * @mul is the PLL multiplier and @div is the common divisor
159 * (pre_pll_clk_div and op_sys_clk_div combined). The final PLL
160 * multiplier will be a multiple of @mul.
162 * @return Zero on success, error code on error.
164 static int __smiapp_pll_calculate(
165 struct device *dev, const struct smiapp_pll_limits *limits,
166 const struct smiapp_pll_branch_limits *op_limits,
167 struct smiapp_pll *pll, struct smiapp_pll_branch *op_pll, uint32_t mul,
168 uint32_t div, uint32_t lane_op_clock_ratio)
171 uint32_t best_pix_div = INT_MAX >> 1;
172 uint32_t vt_op_binning_div;
174 * Higher multipliers (and divisors) are often required than
175 * necessitated by the external clock and the output clocks.
176 * There are limits for all values in the clock tree. These
177 * are the minimum and maximum multiplier for mul.
179 uint32_t more_mul_min, more_mul_max;
180 uint32_t more_mul_factor;
181 uint32_t min_vt_div, max_vt_div, vt_div;
182 uint32_t min_sys_div, max_sys_div;
186 * Get pre_pll_clk_div so that our pll_op_clk_freq_hz won't be
189 dev_dbg(dev, "pre_pll_clk_div %u\n", pll->pre_pll_clk_div);
191 /* Don't go above max pll multiplier. */
192 more_mul_max = limits->max_pll_multiplier / mul;
193 dev_dbg(dev, "more_mul_max: max_pll_multiplier check: %u\n",
195 /* Don't go above max pll op frequency. */
199 limits->max_pll_op_freq_hz
200 / (pll->ext_clk_freq_hz / pll->pre_pll_clk_div * mul));
201 dev_dbg(dev, "more_mul_max: max_pll_op_freq_hz check: %u\n",
203 /* Don't go above the division capability of op sys clock divider. */
204 more_mul_max = min(more_mul_max,
205 op_limits->max_sys_clk_div * pll->pre_pll_clk_div
207 dev_dbg(dev, "more_mul_max: max_op_sys_clk_div check: %u\n",
209 /* Ensure we won't go above min_pll_multiplier. */
210 more_mul_max = min(more_mul_max,
211 DIV_ROUND_UP(limits->max_pll_multiplier, mul));
212 dev_dbg(dev, "more_mul_max: min_pll_multiplier check: %u\n",
215 /* Ensure we won't go below min_pll_op_freq_hz. */
216 more_mul_min = DIV_ROUND_UP(limits->min_pll_op_freq_hz,
217 pll->ext_clk_freq_hz / pll->pre_pll_clk_div
219 dev_dbg(dev, "more_mul_min: min_pll_op_freq_hz check: %u\n",
221 /* Ensure we won't go below min_pll_multiplier. */
222 more_mul_min = max(more_mul_min,
223 DIV_ROUND_UP(limits->min_pll_multiplier, mul));
224 dev_dbg(dev, "more_mul_min: min_pll_multiplier check: %u\n",
227 if (more_mul_min > more_mul_max) {
229 "unable to compute more_mul_min and more_mul_max\n");
233 more_mul_factor = lcm(div, pll->pre_pll_clk_div) / div;
234 dev_dbg(dev, "more_mul_factor: %u\n", more_mul_factor);
235 more_mul_factor = lcm(more_mul_factor, op_limits->min_sys_clk_div);
236 dev_dbg(dev, "more_mul_factor: min_op_sys_clk_div: %d\n",
238 i = roundup(more_mul_min, more_mul_factor);
239 if (!is_one_or_even(i))
242 dev_dbg(dev, "final more_mul: %u\n", i);
243 if (i > more_mul_max) {
244 dev_dbg(dev, "final more_mul is bad, max %u\n", more_mul_max);
248 pll->pll_multiplier = mul * i;
249 op_pll->sys_clk_div = div * i / pll->pre_pll_clk_div;
250 dev_dbg(dev, "op_sys_clk_div: %u\n", op_pll->sys_clk_div);
252 pll->pll_ip_clk_freq_hz = pll->ext_clk_freq_hz
253 / pll->pre_pll_clk_div;
255 pll->pll_op_clk_freq_hz = pll->pll_ip_clk_freq_hz
256 * pll->pll_multiplier;
258 /* Derive pll_op_clk_freq_hz. */
259 op_pll->sys_clk_freq_hz =
260 pll->pll_op_clk_freq_hz / op_pll->sys_clk_div;
262 op_pll->pix_clk_div = pll->bits_per_pixel;
263 dev_dbg(dev, "op_pix_clk_div: %u\n", op_pll->pix_clk_div);
265 op_pll->pix_clk_freq_hz =
266 op_pll->sys_clk_freq_hz / op_pll->pix_clk_div;
268 if (pll->flags & SMIAPP_PLL_FLAG_NO_OP_CLOCKS) {
269 /* No OP clocks --- VT clocks are used instead. */
270 goto out_skip_vt_calc;
274 * Some sensors perform analogue binning and some do this
275 * digitally. The ones doing this digitally can be roughly be
276 * found out using this formula. The ones doing this digitally
277 * should run at higher clock rate, so smaller divisor is used
278 * on video timing side.
280 if (limits->min_line_length_pck_bin > limits->min_line_length_pck
281 / pll->binning_horizontal)
282 vt_op_binning_div = pll->binning_horizontal;
284 vt_op_binning_div = 1;
285 dev_dbg(dev, "vt_op_binning_div: %u\n", vt_op_binning_div);
288 * Profile 2 supports vt_pix_clk_div E [4, 10]
290 * Horizontal binning can be used as a base for difference in
291 * divisors. One must make sure that horizontal blanking is
292 * enough to accommodate the CSI-2 sync codes.
294 * Take scaling factor into account as well.
296 * Find absolute limits for the factor of vt divider.
298 dev_dbg(dev, "scale_m: %u\n", pll->scale_m);
299 min_vt_div = DIV_ROUND_UP(op_pll->pix_clk_div * op_pll->sys_clk_div
301 lane_op_clock_ratio * vt_op_binning_div
304 /* Find smallest and biggest allowed vt divisor. */
305 dev_dbg(dev, "min_vt_div: %u\n", min_vt_div);
306 min_vt_div = max(min_vt_div,
307 DIV_ROUND_UP(pll->pll_op_clk_freq_hz,
308 limits->vt.max_pix_clk_freq_hz));
309 dev_dbg(dev, "min_vt_div: max_vt_pix_clk_freq_hz: %u\n",
311 min_vt_div = max_t(uint32_t, min_vt_div,
312 limits->vt.min_pix_clk_div
313 * limits->vt.min_sys_clk_div);
314 dev_dbg(dev, "min_vt_div: min_vt_clk_div: %u\n", min_vt_div);
316 max_vt_div = limits->vt.max_sys_clk_div * limits->vt.max_pix_clk_div;
317 dev_dbg(dev, "max_vt_div: %u\n", max_vt_div);
318 max_vt_div = min(max_vt_div,
319 DIV_ROUND_UP(pll->pll_op_clk_freq_hz,
320 limits->vt.min_pix_clk_freq_hz));
321 dev_dbg(dev, "max_vt_div: min_vt_pix_clk_freq_hz: %u\n",
325 * Find limitsits for sys_clk_div. Not all values are possible
326 * with all values of pix_clk_div.
328 min_sys_div = limits->vt.min_sys_clk_div;
329 dev_dbg(dev, "min_sys_div: %u\n", min_sys_div);
330 min_sys_div = max(min_sys_div,
331 DIV_ROUND_UP(min_vt_div,
332 limits->vt.max_pix_clk_div));
333 dev_dbg(dev, "min_sys_div: max_vt_pix_clk_div: %u\n", min_sys_div);
334 min_sys_div = max(min_sys_div,
335 pll->pll_op_clk_freq_hz
336 / limits->vt.max_sys_clk_freq_hz);
337 dev_dbg(dev, "min_sys_div: max_pll_op_clk_freq_hz: %u\n", min_sys_div);
338 min_sys_div = clk_div_even_up(min_sys_div);
339 dev_dbg(dev, "min_sys_div: one or even: %u\n", min_sys_div);
341 max_sys_div = limits->vt.max_sys_clk_div;
342 dev_dbg(dev, "max_sys_div: %u\n", max_sys_div);
343 max_sys_div = min(max_sys_div,
344 DIV_ROUND_UP(max_vt_div,
345 limits->vt.min_pix_clk_div));
346 dev_dbg(dev, "max_sys_div: min_vt_pix_clk_div: %u\n", max_sys_div);
347 max_sys_div = min(max_sys_div,
348 DIV_ROUND_UP(pll->pll_op_clk_freq_hz,
349 limits->vt.min_pix_clk_freq_hz));
350 dev_dbg(dev, "max_sys_div: min_vt_pix_clk_freq_hz: %u\n", max_sys_div);
353 * Find pix_div such that a legal pix_div * sys_div results
354 * into a value which is not smaller than div, the desired
357 for (vt_div = min_vt_div; vt_div <= max_vt_div;
358 vt_div += 2 - (vt_div & 1)) {
359 for (sys_div = min_sys_div;
360 sys_div <= max_sys_div;
361 sys_div += 2 - (sys_div & 1)) {
362 uint16_t pix_div = DIV_ROUND_UP(vt_div, sys_div);
364 if (pix_div < limits->vt.min_pix_clk_div
365 || pix_div > limits->vt.max_pix_clk_div) {
367 "pix_div %u too small or too big (%u--%u)\n",
369 limits->vt.min_pix_clk_div,
370 limits->vt.max_pix_clk_div);
374 /* Check if this one is better. */
375 if (pix_div * sys_div
376 <= roundup(min_vt_div, best_pix_div))
377 best_pix_div = pix_div;
379 if (best_pix_div < INT_MAX >> 1)
383 pll->vt.sys_clk_div = DIV_ROUND_UP(min_vt_div, best_pix_div);
384 pll->vt.pix_clk_div = best_pix_div;
386 pll->vt.sys_clk_freq_hz =
387 pll->pll_op_clk_freq_hz / pll->vt.sys_clk_div;
388 pll->vt.pix_clk_freq_hz =
389 pll->vt.sys_clk_freq_hz / pll->vt.pix_clk_div;
392 pll->pixel_rate_csi =
393 op_pll->pix_clk_freq_hz * lane_op_clock_ratio;
394 pll->pixel_rate_pixel_array = pll->vt.pix_clk_freq_hz;
396 return check_all_bounds(dev, limits, op_limits, pll, op_pll);
399 int smiapp_pll_calculate(struct device *dev,
400 const struct smiapp_pll_limits *limits,
401 struct smiapp_pll *pll)
403 const struct smiapp_pll_branch_limits *op_limits = &limits->op;
404 struct smiapp_pll_branch *op_pll = &pll->op;
405 uint16_t min_pre_pll_clk_div;
406 uint16_t max_pre_pll_clk_div;
407 uint32_t lane_op_clock_ratio;
412 if (pll->flags & SMIAPP_PLL_FLAG_NO_OP_CLOCKS) {
414 * If there's no OP PLL at all, use the VT values
415 * instead. The OP values are ignored for the rest of
416 * the PLL calculation.
418 op_limits = &limits->vt;
422 if (pll->flags & SMIAPP_PLL_FLAG_OP_PIX_CLOCK_PER_LANE)
423 lane_op_clock_ratio = pll->csi2.lanes;
425 lane_op_clock_ratio = 1;
426 dev_dbg(dev, "lane_op_clock_ratio: %u\n", lane_op_clock_ratio);
428 dev_dbg(dev, "binning: %ux%u\n", pll->binning_horizontal,
429 pll->binning_vertical);
431 switch (pll->bus_type) {
432 case SMIAPP_PLL_BUS_TYPE_CSI2:
433 /* CSI transfers 2 bits per clock per lane; thus times 2 */
434 pll->pll_op_clk_freq_hz = pll->link_freq * 2
435 * (pll->csi2.lanes / lane_op_clock_ratio);
437 case SMIAPP_PLL_BUS_TYPE_PARALLEL:
438 pll->pll_op_clk_freq_hz = pll->link_freq * pll->bits_per_pixel
439 / DIV_ROUND_UP(pll->bits_per_pixel,
440 pll->parallel.bus_width);
446 /* Figure out limits for pre-pll divider based on extclk */
447 dev_dbg(dev, "min / max pre_pll_clk_div: %u / %u\n",
448 limits->min_pre_pll_clk_div, limits->max_pre_pll_clk_div);
449 max_pre_pll_clk_div =
450 min_t(uint16_t, limits->max_pre_pll_clk_div,
451 clk_div_even(pll->ext_clk_freq_hz /
452 limits->min_pll_ip_freq_hz));
453 min_pre_pll_clk_div =
454 max_t(uint16_t, limits->min_pre_pll_clk_div,
456 DIV_ROUND_UP(pll->ext_clk_freq_hz,
457 limits->max_pll_ip_freq_hz)));
458 dev_dbg(dev, "pre-pll check: min / max pre_pll_clk_div: %u / %u\n",
459 min_pre_pll_clk_div, max_pre_pll_clk_div);
461 i = gcd(pll->pll_op_clk_freq_hz, pll->ext_clk_freq_hz);
462 mul = div_u64(pll->pll_op_clk_freq_hz, i);
463 div = pll->ext_clk_freq_hz / i;
464 dev_dbg(dev, "mul %u / div %u\n", mul, div);
466 min_pre_pll_clk_div =
467 max_t(uint16_t, min_pre_pll_clk_div,
469 DIV_ROUND_UP(mul * pll->ext_clk_freq_hz,
470 limits->max_pll_op_freq_hz)));
471 dev_dbg(dev, "pll_op check: min / max pre_pll_clk_div: %u / %u\n",
472 min_pre_pll_clk_div, max_pre_pll_clk_div);
474 for (pll->pre_pll_clk_div = min_pre_pll_clk_div;
475 pll->pre_pll_clk_div <= max_pre_pll_clk_div;
476 pll->pre_pll_clk_div += 2 - (pll->pre_pll_clk_div & 1)) {
477 rval = __smiapp_pll_calculate(dev, limits, op_limits, pll,
479 lane_op_clock_ratio);
487 dev_info(dev, "unable to compute pre_pll divisor\n");
490 EXPORT_SYMBOL_GPL(smiapp_pll_calculate);
492 MODULE_AUTHOR("Sakari Ailus <sakari.ailus@iki.fi>");
493 MODULE_DESCRIPTION("Generic SMIA/SMIA++ PLL calculator");
494 MODULE_LICENSE("GPL");