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.
19 #include <linux/device.h>
20 #include <linux/gcd.h>
21 #include <linux/lcm.h>
22 #include <linux/module.h>
24 #include "smiapp-pll.h"
26 /* Return an even number or one. */
27 static inline uint32_t clk_div_even(uint32_t a
)
29 return max_t(uint32_t, 1, a
& ~1);
32 /* Return an even number or one. */
33 static inline uint32_t clk_div_even_up(uint32_t a
)
40 static inline uint32_t is_one_or_even(uint32_t a
)
50 static int bounds_check(struct device
*dev
, uint32_t val
,
51 uint32_t min
, uint32_t max
, char *str
)
53 if (val
>= min
&& val
<= max
)
56 dev_dbg(dev
, "%s out of bounds: %d (%d--%d)\n", str
, val
, min
, max
);
61 static void print_pll(struct device
*dev
, struct smiapp_pll
*pll
)
63 dev_dbg(dev
, "pre_pll_clk_div\t%u\n", pll
->pre_pll_clk_div
);
64 dev_dbg(dev
, "pll_multiplier \t%u\n", pll
->pll_multiplier
);
65 if (!(pll
->flags
& SMIAPP_PLL_FLAG_NO_OP_CLOCKS
)) {
66 dev_dbg(dev
, "op_sys_clk_div \t%u\n", pll
->op
.sys_clk_div
);
67 dev_dbg(dev
, "op_pix_clk_div \t%u\n", pll
->op
.pix_clk_div
);
69 dev_dbg(dev
, "vt_sys_clk_div \t%u\n", pll
->vt
.sys_clk_div
);
70 dev_dbg(dev
, "vt_pix_clk_div \t%u\n", pll
->vt
.pix_clk_div
);
72 dev_dbg(dev
, "ext_clk_freq_hz \t%u\n", pll
->ext_clk_freq_hz
);
73 dev_dbg(dev
, "pll_ip_clk_freq_hz \t%u\n", pll
->pll_ip_clk_freq_hz
);
74 dev_dbg(dev
, "pll_op_clk_freq_hz \t%u\n", pll
->pll_op_clk_freq_hz
);
75 if (!(pll
->flags
& SMIAPP_PLL_FLAG_NO_OP_CLOCKS
)) {
76 dev_dbg(dev
, "op_sys_clk_freq_hz \t%u\n",
77 pll
->op
.sys_clk_freq_hz
);
78 dev_dbg(dev
, "op_pix_clk_freq_hz \t%u\n",
79 pll
->op
.pix_clk_freq_hz
);
81 dev_dbg(dev
, "vt_sys_clk_freq_hz \t%u\n", pll
->vt
.sys_clk_freq_hz
);
82 dev_dbg(dev
, "vt_pix_clk_freq_hz \t%u\n", pll
->vt
.pix_clk_freq_hz
);
85 static int check_all_bounds(struct device
*dev
,
86 const struct smiapp_pll_limits
*limits
,
87 const struct smiapp_pll_branch_limits
*op_limits
,
88 struct smiapp_pll
*pll
,
89 struct smiapp_pll_branch
*op_pll
)
93 rval
= bounds_check(dev
, pll
->pll_ip_clk_freq_hz
,
94 limits
->min_pll_ip_freq_hz
,
95 limits
->max_pll_ip_freq_hz
,
96 "pll_ip_clk_freq_hz");
99 dev
, pll
->pll_multiplier
,
100 limits
->min_pll_multiplier
, limits
->max_pll_multiplier
,
104 dev
, pll
->pll_op_clk_freq_hz
,
105 limits
->min_pll_op_freq_hz
, limits
->max_pll_op_freq_hz
,
106 "pll_op_clk_freq_hz");
109 dev
, op_pll
->sys_clk_div
,
110 op_limits
->min_sys_clk_div
, op_limits
->max_sys_clk_div
,
114 dev
, op_pll
->sys_clk_freq_hz
,
115 op_limits
->min_sys_clk_freq_hz
,
116 op_limits
->max_sys_clk_freq_hz
,
117 "op_sys_clk_freq_hz");
120 dev
, op_pll
->pix_clk_freq_hz
,
121 op_limits
->min_pix_clk_freq_hz
,
122 op_limits
->max_pix_clk_freq_hz
,
123 "op_pix_clk_freq_hz");
126 * If there are no OP clocks, the VT clocks are contained in
127 * the OP clock struct.
129 if (pll
->flags
& SMIAPP_PLL_FLAG_NO_OP_CLOCKS
)
134 dev
, pll
->vt
.sys_clk_freq_hz
,
135 limits
->vt
.min_sys_clk_freq_hz
,
136 limits
->vt
.max_sys_clk_freq_hz
,
137 "vt_sys_clk_freq_hz");
140 dev
, pll
->vt
.pix_clk_freq_hz
,
141 limits
->vt
.min_pix_clk_freq_hz
,
142 limits
->vt
.max_pix_clk_freq_hz
,
143 "vt_pix_clk_freq_hz");
149 * Heuristically guess the PLL tree for a given common multiplier and
150 * divisor. Begin with the operational timing and continue to video
151 * timing once operational timing has been verified.
153 * @mul is the PLL multiplier and @div is the common divisor
154 * (pre_pll_clk_div and op_sys_clk_div combined). The final PLL
155 * multiplier will be a multiple of @mul.
157 * @return Zero on success, error code on error.
159 static int __smiapp_pll_calculate(
160 struct device
*dev
, const struct smiapp_pll_limits
*limits
,
161 const struct smiapp_pll_branch_limits
*op_limits
,
162 struct smiapp_pll
*pll
, struct smiapp_pll_branch
*op_pll
, uint32_t mul
,
163 uint32_t div
, uint32_t lane_op_clock_ratio
)
166 uint32_t best_pix_div
= INT_MAX
>> 1;
167 uint32_t vt_op_binning_div
;
169 * Higher multipliers (and divisors) are often required than
170 * necessitated by the external clock and the output clocks.
171 * There are limits for all values in the clock tree. These
172 * are the minimum and maximum multiplier for mul.
174 uint32_t more_mul_min
, more_mul_max
;
175 uint32_t more_mul_factor
;
176 uint32_t min_vt_div
, max_vt_div
, vt_div
;
177 uint32_t min_sys_div
, max_sys_div
;
181 * Get pre_pll_clk_div so that our pll_op_clk_freq_hz won't be
184 dev_dbg(dev
, "pre_pll_clk_div %u\n", pll
->pre_pll_clk_div
);
186 /* Don't go above max pll multiplier. */
187 more_mul_max
= limits
->max_pll_multiplier
/ mul
;
188 dev_dbg(dev
, "more_mul_max: max_pll_multiplier check: %u\n",
190 /* Don't go above max pll op frequency. */
194 limits
->max_pll_op_freq_hz
195 / (pll
->ext_clk_freq_hz
/ pll
->pre_pll_clk_div
* mul
));
196 dev_dbg(dev
, "more_mul_max: max_pll_op_freq_hz check: %u\n",
198 /* Don't go above the division capability of op sys clock divider. */
199 more_mul_max
= min(more_mul_max
,
200 op_limits
->max_sys_clk_div
* pll
->pre_pll_clk_div
202 dev_dbg(dev
, "more_mul_max: max_op_sys_clk_div check: %u\n",
204 /* Ensure we won't go above min_pll_multiplier. */
205 more_mul_max
= min(more_mul_max
,
206 DIV_ROUND_UP(limits
->max_pll_multiplier
, mul
));
207 dev_dbg(dev
, "more_mul_max: min_pll_multiplier check: %u\n",
210 /* Ensure we won't go below min_pll_op_freq_hz. */
211 more_mul_min
= DIV_ROUND_UP(limits
->min_pll_op_freq_hz
,
212 pll
->ext_clk_freq_hz
/ pll
->pre_pll_clk_div
214 dev_dbg(dev
, "more_mul_min: min_pll_op_freq_hz check: %u\n",
216 /* Ensure we won't go below min_pll_multiplier. */
217 more_mul_min
= max(more_mul_min
,
218 DIV_ROUND_UP(limits
->min_pll_multiplier
, mul
));
219 dev_dbg(dev
, "more_mul_min: min_pll_multiplier check: %u\n",
222 if (more_mul_min
> more_mul_max
) {
224 "unable to compute more_mul_min and more_mul_max\n");
228 more_mul_factor
= lcm(div
, pll
->pre_pll_clk_div
) / div
;
229 dev_dbg(dev
, "more_mul_factor: %u\n", more_mul_factor
);
230 more_mul_factor
= lcm(more_mul_factor
, op_limits
->min_sys_clk_div
);
231 dev_dbg(dev
, "more_mul_factor: min_op_sys_clk_div: %d\n",
233 i
= roundup(more_mul_min
, more_mul_factor
);
234 if (!is_one_or_even(i
))
237 dev_dbg(dev
, "final more_mul: %u\n", i
);
238 if (i
> more_mul_max
) {
239 dev_dbg(dev
, "final more_mul is bad, max %u\n", more_mul_max
);
243 pll
->pll_multiplier
= mul
* i
;
244 op_pll
->sys_clk_div
= div
* i
/ pll
->pre_pll_clk_div
;
245 dev_dbg(dev
, "op_sys_clk_div: %u\n", op_pll
->sys_clk_div
);
247 pll
->pll_ip_clk_freq_hz
= pll
->ext_clk_freq_hz
248 / pll
->pre_pll_clk_div
;
250 pll
->pll_op_clk_freq_hz
= pll
->pll_ip_clk_freq_hz
251 * pll
->pll_multiplier
;
253 /* Derive pll_op_clk_freq_hz. */
254 op_pll
->sys_clk_freq_hz
=
255 pll
->pll_op_clk_freq_hz
/ op_pll
->sys_clk_div
;
257 op_pll
->pix_clk_div
= pll
->bits_per_pixel
;
258 dev_dbg(dev
, "op_pix_clk_div: %u\n", op_pll
->pix_clk_div
);
260 op_pll
->pix_clk_freq_hz
=
261 op_pll
->sys_clk_freq_hz
/ op_pll
->pix_clk_div
;
263 if (pll
->flags
& SMIAPP_PLL_FLAG_NO_OP_CLOCKS
) {
264 /* No OP clocks --- VT clocks are used instead. */
265 goto out_skip_vt_calc
;
269 * Some sensors perform analogue binning and some do this
270 * digitally. The ones doing this digitally can be roughly be
271 * found out using this formula. The ones doing this digitally
272 * should run at higher clock rate, so smaller divisor is used
273 * on video timing side.
275 if (limits
->min_line_length_pck_bin
> limits
->min_line_length_pck
276 / pll
->binning_horizontal
)
277 vt_op_binning_div
= pll
->binning_horizontal
;
279 vt_op_binning_div
= 1;
280 dev_dbg(dev
, "vt_op_binning_div: %u\n", vt_op_binning_div
);
283 * Profile 2 supports vt_pix_clk_div E [4, 10]
285 * Horizontal binning can be used as a base for difference in
286 * divisors. One must make sure that horizontal blanking is
287 * enough to accommodate the CSI-2 sync codes.
289 * Take scaling factor into account as well.
291 * Find absolute limits for the factor of vt divider.
293 dev_dbg(dev
, "scale_m: %u\n", pll
->scale_m
);
294 min_vt_div
= DIV_ROUND_UP(op_pll
->pix_clk_div
* op_pll
->sys_clk_div
296 lane_op_clock_ratio
* vt_op_binning_div
299 /* Find smallest and biggest allowed vt divisor. */
300 dev_dbg(dev
, "min_vt_div: %u\n", min_vt_div
);
301 min_vt_div
= max(min_vt_div
,
302 DIV_ROUND_UP(pll
->pll_op_clk_freq_hz
,
303 limits
->vt
.max_pix_clk_freq_hz
));
304 dev_dbg(dev
, "min_vt_div: max_vt_pix_clk_freq_hz: %u\n",
306 min_vt_div
= max_t(uint32_t, min_vt_div
,
307 limits
->vt
.min_pix_clk_div
308 * limits
->vt
.min_sys_clk_div
);
309 dev_dbg(dev
, "min_vt_div: min_vt_clk_div: %u\n", min_vt_div
);
311 max_vt_div
= limits
->vt
.max_sys_clk_div
* limits
->vt
.max_pix_clk_div
;
312 dev_dbg(dev
, "max_vt_div: %u\n", max_vt_div
);
313 max_vt_div
= min(max_vt_div
,
314 DIV_ROUND_UP(pll
->pll_op_clk_freq_hz
,
315 limits
->vt
.min_pix_clk_freq_hz
));
316 dev_dbg(dev
, "max_vt_div: min_vt_pix_clk_freq_hz: %u\n",
320 * Find limitsits for sys_clk_div. Not all values are possible
321 * with all values of pix_clk_div.
323 min_sys_div
= limits
->vt
.min_sys_clk_div
;
324 dev_dbg(dev
, "min_sys_div: %u\n", min_sys_div
);
325 min_sys_div
= max(min_sys_div
,
326 DIV_ROUND_UP(min_vt_div
,
327 limits
->vt
.max_pix_clk_div
));
328 dev_dbg(dev
, "min_sys_div: max_vt_pix_clk_div: %u\n", min_sys_div
);
329 min_sys_div
= max(min_sys_div
,
330 pll
->pll_op_clk_freq_hz
331 / limits
->vt
.max_sys_clk_freq_hz
);
332 dev_dbg(dev
, "min_sys_div: max_pll_op_clk_freq_hz: %u\n", min_sys_div
);
333 min_sys_div
= clk_div_even_up(min_sys_div
);
334 dev_dbg(dev
, "min_sys_div: one or even: %u\n", min_sys_div
);
336 max_sys_div
= limits
->vt
.max_sys_clk_div
;
337 dev_dbg(dev
, "max_sys_div: %u\n", max_sys_div
);
338 max_sys_div
= min(max_sys_div
,
339 DIV_ROUND_UP(max_vt_div
,
340 limits
->vt
.min_pix_clk_div
));
341 dev_dbg(dev
, "max_sys_div: min_vt_pix_clk_div: %u\n", max_sys_div
);
342 max_sys_div
= min(max_sys_div
,
343 DIV_ROUND_UP(pll
->pll_op_clk_freq_hz
,
344 limits
->vt
.min_pix_clk_freq_hz
));
345 dev_dbg(dev
, "max_sys_div: min_vt_pix_clk_freq_hz: %u\n", max_sys_div
);
348 * Find pix_div such that a legal pix_div * sys_div results
349 * into a value which is not smaller than div, the desired
352 for (vt_div
= min_vt_div
; vt_div
<= max_vt_div
;
353 vt_div
+= 2 - (vt_div
& 1)) {
354 for (sys_div
= min_sys_div
;
355 sys_div
<= max_sys_div
;
356 sys_div
+= 2 - (sys_div
& 1)) {
357 uint16_t pix_div
= DIV_ROUND_UP(vt_div
, sys_div
);
359 if (pix_div
< limits
->vt
.min_pix_clk_div
360 || pix_div
> limits
->vt
.max_pix_clk_div
) {
362 "pix_div %u too small or too big (%u--%u)\n",
364 limits
->vt
.min_pix_clk_div
,
365 limits
->vt
.max_pix_clk_div
);
369 /* Check if this one is better. */
370 if (pix_div
* sys_div
371 <= roundup(min_vt_div
, best_pix_div
))
372 best_pix_div
= pix_div
;
374 if (best_pix_div
< INT_MAX
>> 1)
378 pll
->vt
.sys_clk_div
= DIV_ROUND_UP(min_vt_div
, best_pix_div
);
379 pll
->vt
.pix_clk_div
= best_pix_div
;
381 pll
->vt
.sys_clk_freq_hz
=
382 pll
->pll_op_clk_freq_hz
/ pll
->vt
.sys_clk_div
;
383 pll
->vt
.pix_clk_freq_hz
=
384 pll
->vt
.sys_clk_freq_hz
/ pll
->vt
.pix_clk_div
;
387 pll
->pixel_rate_csi
=
388 op_pll
->pix_clk_freq_hz
* lane_op_clock_ratio
;
389 pll
->pixel_rate_pixel_array
= pll
->vt
.pix_clk_freq_hz
;
391 return check_all_bounds(dev
, limits
, op_limits
, pll
, op_pll
);
394 int smiapp_pll_calculate(struct device
*dev
,
395 const struct smiapp_pll_limits
*limits
,
396 struct smiapp_pll
*pll
)
398 const struct smiapp_pll_branch_limits
*op_limits
= &limits
->op
;
399 struct smiapp_pll_branch
*op_pll
= &pll
->op
;
400 uint16_t min_pre_pll_clk_div
;
401 uint16_t max_pre_pll_clk_div
;
402 uint32_t lane_op_clock_ratio
;
407 if (pll
->flags
& SMIAPP_PLL_FLAG_NO_OP_CLOCKS
) {
409 * If there's no OP PLL at all, use the VT values
410 * instead. The OP values are ignored for the rest of
411 * the PLL calculation.
413 op_limits
= &limits
->vt
;
417 if (pll
->flags
& SMIAPP_PLL_FLAG_OP_PIX_CLOCK_PER_LANE
)
418 lane_op_clock_ratio
= pll
->csi2
.lanes
;
420 lane_op_clock_ratio
= 1;
421 dev_dbg(dev
, "lane_op_clock_ratio: %u\n", lane_op_clock_ratio
);
423 dev_dbg(dev
, "binning: %ux%u\n", pll
->binning_horizontal
,
424 pll
->binning_vertical
);
426 switch (pll
->bus_type
) {
427 case SMIAPP_PLL_BUS_TYPE_CSI2
:
428 /* CSI transfers 2 bits per clock per lane; thus times 2 */
429 pll
->pll_op_clk_freq_hz
= pll
->link_freq
* 2
430 * (pll
->csi2
.lanes
/ lane_op_clock_ratio
);
432 case SMIAPP_PLL_BUS_TYPE_PARALLEL
:
433 pll
->pll_op_clk_freq_hz
= pll
->link_freq
* pll
->bits_per_pixel
434 / DIV_ROUND_UP(pll
->bits_per_pixel
,
435 pll
->parallel
.bus_width
);
441 /* Figure out limits for pre-pll divider based on extclk */
442 dev_dbg(dev
, "min / max pre_pll_clk_div: %u / %u\n",
443 limits
->min_pre_pll_clk_div
, limits
->max_pre_pll_clk_div
);
444 max_pre_pll_clk_div
=
445 min_t(uint16_t, limits
->max_pre_pll_clk_div
,
446 clk_div_even(pll
->ext_clk_freq_hz
/
447 limits
->min_pll_ip_freq_hz
));
448 min_pre_pll_clk_div
=
449 max_t(uint16_t, limits
->min_pre_pll_clk_div
,
451 DIV_ROUND_UP(pll
->ext_clk_freq_hz
,
452 limits
->max_pll_ip_freq_hz
)));
453 dev_dbg(dev
, "pre-pll check: min / max pre_pll_clk_div: %u / %u\n",
454 min_pre_pll_clk_div
, max_pre_pll_clk_div
);
456 i
= gcd(pll
->pll_op_clk_freq_hz
, pll
->ext_clk_freq_hz
);
457 mul
= div_u64(pll
->pll_op_clk_freq_hz
, i
);
458 div
= pll
->ext_clk_freq_hz
/ i
;
459 dev_dbg(dev
, "mul %u / div %u\n", mul
, div
);
461 min_pre_pll_clk_div
=
462 max_t(uint16_t, min_pre_pll_clk_div
,
464 DIV_ROUND_UP(mul
* pll
->ext_clk_freq_hz
,
465 limits
->max_pll_op_freq_hz
)));
466 dev_dbg(dev
, "pll_op check: min / max pre_pll_clk_div: %u / %u\n",
467 min_pre_pll_clk_div
, max_pre_pll_clk_div
);
469 for (pll
->pre_pll_clk_div
= min_pre_pll_clk_div
;
470 pll
->pre_pll_clk_div
<= max_pre_pll_clk_div
;
471 pll
->pre_pll_clk_div
+= 2 - (pll
->pre_pll_clk_div
& 1)) {
472 rval
= __smiapp_pll_calculate(dev
, limits
, op_limits
, pll
,
474 lane_op_clock_ratio
);
482 dev_info(dev
, "unable to compute pre_pll divisor\n");
485 EXPORT_SYMBOL_GPL(smiapp_pll_calculate
);
487 MODULE_AUTHOR("Sakari Ailus <sakari.ailus@iki.fi>");
488 MODULE_DESCRIPTION("Generic SMIA/SMIA++ PLL calculator");
489 MODULE_LICENSE("GPL");