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Paul Walmsleydf791b32010-01-26 20:13:04 -07001/*
2 * clkt_clksel.c - OMAP2/3/4 clksel clock functions
3 *
4 * Copyright (C) 2005-2008 Texas Instruments, Inc.
5 * Copyright (C) 2004-2010 Nokia Corporation
6 *
7 * Contacts:
8 * Richard Woodruff <r-woodruff2@ti.com>
9 * Paul Walmsley
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License version 2 as
13 * published by the Free Software Foundation.
14 *
Paul Walmsley435699d2010-05-18 18:40:24 -060015 *
16 * clksel clocks are clocks that do not have a fixed parent, or that
17 * can divide their parent's rate, or possibly both at the same time, based
18 * on the contents of a hardware register bitfield.
19 *
20 * All of the various mux and divider settings can be encoded into
21 * struct clksel* data structures, and then these can be autogenerated
22 * from some hardware database for each new chip generation. This
23 * should avoid the need to write, review, and validate a lot of new
24 * clock code for each new chip, since it can be exported from the SoC
25 * design flow. This is now done on OMAP4.
26 *
27 * The fusion of mux and divider clocks is a software creation. In
28 * hardware reality, the multiplexer (parent selection) and the
29 * divider exist separately. XXX At some point these clksel clocks
30 * should be split into "divider" clocks and "mux" clocks to better
31 * match the hardware.
32 *
33 * (The name "clksel" comes from the name of the corresponding
34 * register field in the OMAP2/3 family of SoCs.)
Paul Walmsleydf791b32010-01-26 20:13:04 -070035 *
36 * XXX Currently these clocks are only used in the OMAP2/3/4 code, but
37 * many of the OMAP1 clocks should be convertible to use this
38 * mechanism.
39 */
40#undef DEBUG
41
42#include <linux/kernel.h>
43#include <linux/errno.h>
44#include <linux/clk.h>
45#include <linux/io.h>
46
47#include <plat/clock.h>
48
49#include "clock.h"
Paul Walmsleydf791b32010-01-26 20:13:04 -070050
51/* Private functions */
52
53/**
Paul Walmsley435699d2010-05-18 18:40:24 -060054 * _get_clksel_by_parent() - return clksel struct for a given clk & parent
Paul Walmsleydf791b32010-01-26 20:13:04 -070055 * @clk: OMAP struct clk ptr to inspect
56 * @src_clk: OMAP struct clk ptr of the parent clk to search for
57 *
58 * Scan the struct clksel array associated with the clock to find
59 * the element associated with the supplied parent clock address.
60 * Returns a pointer to the struct clksel on success or NULL on error.
61 */
Paul Walmsley435699d2010-05-18 18:40:24 -060062static const struct clksel *_get_clksel_by_parent(struct clk *clk,
63 struct clk *src_clk)
Paul Walmsleydf791b32010-01-26 20:13:04 -070064{
65 const struct clksel *clks;
66
Paul Walmsley435699d2010-05-18 18:40:24 -060067 for (clks = clk->clksel; clks->parent; clks++)
Paul Walmsleydf791b32010-01-26 20:13:04 -070068 if (clks->parent == src_clk)
69 break; /* Found the requested parent */
Paul Walmsleydf791b32010-01-26 20:13:04 -070070
71 if (!clks->parent) {
Paul Walmsley435699d2010-05-18 18:40:24 -060072 /* This indicates a data problem */
73 WARN(1, "clock: Could not find parent clock %s in clksel array "
74 "of clock %s\n", src_clk->name, clk->name);
Paul Walmsleydf791b32010-01-26 20:13:04 -070075 return NULL;
76 }
77
78 return clks;
79}
80
Paul Walmsleyd74b4942010-05-18 18:40:24 -060081/**
Paul Walmsley435699d2010-05-18 18:40:24 -060082 * _get_div_and_fieldval() - find the new clksel divisor and field value to use
Paul Walmsleyd74b4942010-05-18 18:40:24 -060083 * @src_clk: planned new parent struct clk *
84 * @clk: struct clk * that is being reparented
85 * @field_val: pointer to a u32 to contain the register data for the divisor
86 *
87 * Given an intended new parent struct clk * @src_clk, and the struct
88 * clk * @clk to the clock that is being reparented, find the
89 * appropriate rate divisor for the new clock (returned as the return
90 * value), and the corresponding register bitfield data to program to
91 * reach that divisor (returned in the u32 pointed to by @field_val).
92 * Returns 0 on error, or returns the newly-selected divisor upon
93 * success (in this latter case, the corresponding register bitfield
94 * value is passed back in the variable pointed to by @field_val)
Paul Walmsleydf791b32010-01-26 20:13:04 -070095 */
Paul Walmsley435699d2010-05-18 18:40:24 -060096static u8 _get_div_and_fieldval(struct clk *src_clk, struct clk *clk,
97 u32 *field_val)
Paul Walmsleydf791b32010-01-26 20:13:04 -070098{
99 const struct clksel *clks;
Felipe Balbi405505c2011-01-16 13:22:03 +0200100 const struct clksel_rate *clkr, *max_clkr = NULL;
Paul Walmsleyd74b4942010-05-18 18:40:24 -0600101 u8 max_div = 0;
Paul Walmsleydf791b32010-01-26 20:13:04 -0700102
Paul Walmsley435699d2010-05-18 18:40:24 -0600103 clks = _get_clksel_by_parent(clk, src_clk);
Paul Walmsleydf791b32010-01-26 20:13:04 -0700104 if (!clks)
105 return 0;
106
Paul Walmsleyd74b4942010-05-18 18:40:24 -0600107 /*
108 * Find the highest divisor (e.g., the one resulting in the
109 * lowest rate) to use as the default. This should avoid
110 * clock rates that are too high for the device. XXX A better
111 * solution here would be to try to determine if there is a
112 * divisor matching the original clock rate before the parent
113 * switch, and if it cannot be found, to fall back to the
114 * highest divisor.
115 */
Paul Walmsleydf791b32010-01-26 20:13:04 -0700116 for (clkr = clks->rates; clkr->div; clkr++) {
Paul Walmsleyd74b4942010-05-18 18:40:24 -0600117 if (!(clkr->flags & cpu_mask))
118 continue;
119
120 if (clkr->div > max_div) {
121 max_div = clkr->div;
122 max_clkr = clkr;
123 }
Paul Walmsleydf791b32010-01-26 20:13:04 -0700124 }
125
Paul Walmsleyd74b4942010-05-18 18:40:24 -0600126 if (max_div == 0) {
Paul Walmsley435699d2010-05-18 18:40:24 -0600127 /* This indicates an error in the clksel data */
128 WARN(1, "clock: Could not find divisor for clock %s parent %s"
129 "\n", clk->name, src_clk->parent->name);
Paul Walmsleydf791b32010-01-26 20:13:04 -0700130 return 0;
131 }
132
Paul Walmsleyd74b4942010-05-18 18:40:24 -0600133 *field_val = max_clkr->val;
Paul Walmsleydf791b32010-01-26 20:13:04 -0700134
Paul Walmsleyd74b4942010-05-18 18:40:24 -0600135 return max_div;
Paul Walmsleydf791b32010-01-26 20:13:04 -0700136}
137
Paul Walmsley435699d2010-05-18 18:40:24 -0600138/**
139 * _write_clksel_reg() - program a clock's clksel register in hardware
140 * @clk: struct clk * to program
141 * @v: clksel bitfield value to program (with LSB at bit 0)
142 *
143 * Shift the clksel register bitfield value @v to its appropriate
144 * location in the clksel register and write it in. This function
145 * will ensure that the write to the clksel_reg reaches its
146 * destination before returning -- important since PRM and CM register
147 * accesses can be quite slow compared to ARM cycles -- but does not
148 * take into account any time the hardware might take to switch the
149 * clock source.
150 */
151static void _write_clksel_reg(struct clk *clk, u32 field_val)
152{
153 u32 v;
154
155 v = __raw_readl(clk->clksel_reg);
156 v &= ~clk->clksel_mask;
157 v |= field_val << __ffs(clk->clksel_mask);
158 __raw_writel(v, clk->clksel_reg);
159
160 v = __raw_readl(clk->clksel_reg); /* OCP barrier */
161}
162
163/**
164 * _clksel_to_divisor() - turn clksel field value into integer divider
165 * @clk: OMAP struct clk to use
166 * @field_val: register field value to find
167 *
168 * Given a struct clk of a rate-selectable clksel clock, and a register field
169 * value to search for, find the corresponding clock divisor. The register
170 * field value should be pre-masked and shifted down so the LSB is at bit 0
171 * before calling. Returns 0 on error or returns the actual integer divisor
172 * upon success.
173 */
174static u32 _clksel_to_divisor(struct clk *clk, u32 field_val)
175{
176 const struct clksel *clks;
177 const struct clksel_rate *clkr;
178
179 clks = _get_clksel_by_parent(clk, clk->parent);
180 if (!clks)
181 return 0;
182
183 for (clkr = clks->rates; clkr->div; clkr++) {
184 if (!(clkr->flags & cpu_mask))
185 continue;
186
187 if (clkr->val == field_val)
188 break;
189 }
190
191 if (!clkr->div) {
192 /* This indicates a data error */
193 WARN(1, "clock: Could not find fieldval %d for clock %s parent "
194 "%s\n", field_val, clk->name, clk->parent->name);
195 return 0;
196 }
197
198 return clkr->div;
199}
200
201/**
202 * _divisor_to_clksel() - turn clksel integer divisor into a field value
203 * @clk: OMAP struct clk to use
204 * @div: integer divisor to search for
205 *
206 * Given a struct clk of a rate-selectable clksel clock, and a clock
207 * divisor, find the corresponding register field value. Returns the
208 * register field value _before_ left-shifting (i.e., LSB is at bit
209 * 0); or returns 0xFFFFFFFF (~0) upon error.
210 */
211static u32 _divisor_to_clksel(struct clk *clk, u32 div)
212{
213 const struct clksel *clks;
214 const struct clksel_rate *clkr;
215
216 /* should never happen */
217 WARN_ON(div == 0);
218
219 clks = _get_clksel_by_parent(clk, clk->parent);
220 if (!clks)
221 return ~0;
222
223 for (clkr = clks->rates; clkr->div; clkr++) {
224 if (!(clkr->flags & cpu_mask))
225 continue;
226
227 if (clkr->div == div)
228 break;
229 }
230
231 if (!clkr->div) {
232 pr_err("clock: Could not find divisor %d for clock %s parent "
233 "%s\n", div, clk->name, clk->parent->name);
234 return ~0;
235 }
236
237 return clkr->val;
238}
239
240/**
241 * _read_divisor() - get current divisor applied to parent clock (from hdwr)
242 * @clk: OMAP struct clk to use.
243 *
244 * Read the current divisor register value for @clk that is programmed
245 * into the hardware, convert it into the actual divisor value, and
246 * return it; or return 0 on error.
247 */
248static u32 _read_divisor(struct clk *clk)
249{
250 u32 v;
251
252 if (!clk->clksel || !clk->clksel_mask)
253 return 0;
254
255 v = __raw_readl(clk->clksel_reg);
256 v &= clk->clksel_mask;
257 v >>= __ffs(clk->clksel_mask);
258
259 return _clksel_to_divisor(clk, v);
260}
Paul Walmsleydf791b32010-01-26 20:13:04 -0700261
262/* Public functions */
263
264/**
Paul Walmsley435699d2010-05-18 18:40:24 -0600265 * omap2_clksel_round_rate_div() - find divisor for the given clock and rate
Paul Walmsleydf791b32010-01-26 20:13:04 -0700266 * @clk: OMAP struct clk to use
267 * @target_rate: desired clock rate
268 * @new_div: ptr to where we should store the divisor
269 *
270 * Finds 'best' divider value in an array based on the source and target
271 * rates. The divider array must be sorted with smallest divider first.
Paul Walmsley435699d2010-05-18 18:40:24 -0600272 * This function is also used by the DPLL3 M2 divider code.
Paul Walmsleydf791b32010-01-26 20:13:04 -0700273 *
274 * Returns the rounded clock rate or returns 0xffffffff on error.
275 */
276u32 omap2_clksel_round_rate_div(struct clk *clk, unsigned long target_rate,
277 u32 *new_div)
278{
279 unsigned long test_rate;
280 const struct clksel *clks;
281 const struct clksel_rate *clkr;
282 u32 last_div = 0;
283
Paul Walmsley435699d2010-05-18 18:40:24 -0600284 if (!clk->clksel || !clk->clksel_mask)
285 return ~0;
286
Paul Walmsleydf791b32010-01-26 20:13:04 -0700287 pr_debug("clock: clksel_round_rate_div: %s target_rate %ld\n",
288 clk->name, target_rate);
289
290 *new_div = 1;
291
Paul Walmsley435699d2010-05-18 18:40:24 -0600292 clks = _get_clksel_by_parent(clk, clk->parent);
Paul Walmsleydf791b32010-01-26 20:13:04 -0700293 if (!clks)
294 return ~0;
295
296 for (clkr = clks->rates; clkr->div; clkr++) {
297 if (!(clkr->flags & cpu_mask))
298 continue;
299
300 /* Sanity check */
301 if (clkr->div <= last_div)
302 pr_err("clock: clksel_rate table not sorted "
303 "for clock %s", clk->name);
304
305 last_div = clkr->div;
306
307 test_rate = clk->parent->rate / clkr->div;
308
309 if (test_rate <= target_rate)
310 break; /* found it */
311 }
312
313 if (!clkr->div) {
314 pr_err("clock: Could not find divisor for target "
315 "rate %ld for clock %s parent %s\n", target_rate,
316 clk->name, clk->parent->name);
317 return ~0;
318 }
319
320 *new_div = clkr->div;
321
322 pr_debug("clock: new_div = %d, new_rate = %ld\n", *new_div,
323 (clk->parent->rate / clkr->div));
324
325 return clk->parent->rate / clkr->div;
326}
327
Paul Walmsley435699d2010-05-18 18:40:24 -0600328/*
329 * Clocktype interface functions to the OMAP clock code
330 * (i.e., those used in struct clk field function pointers, etc.)
331 */
332
Paul Walmsleydf791b32010-01-26 20:13:04 -0700333/**
Paul Walmsley435699d2010-05-18 18:40:24 -0600334 * omap2_init_clksel_parent() - set a clksel clk's parent field from the hdwr
335 * @clk: OMAP clock struct ptr to use
336 *
337 * Given a pointer @clk to a source-selectable struct clk, read the
338 * hardware register and determine what its parent is currently set
339 * to. Update @clk's .parent field with the appropriate clk ptr. No
340 * return value.
341 */
342void omap2_init_clksel_parent(struct clk *clk)
343{
344 const struct clksel *clks;
345 const struct clksel_rate *clkr;
346 u32 r, found = 0;
347
348 if (!clk->clksel || !clk->clksel_mask)
349 return;
350
351 r = __raw_readl(clk->clksel_reg) & clk->clksel_mask;
352 r >>= __ffs(clk->clksel_mask);
353
354 for (clks = clk->clksel; clks->parent && !found; clks++) {
355 for (clkr = clks->rates; clkr->div && !found; clkr++) {
356 if (!(clkr->flags & cpu_mask))
357 continue;
358
359 if (clkr->val == r) {
360 if (clk->parent != clks->parent) {
361 pr_debug("clock: inited %s parent "
362 "to %s (was %s)\n",
363 clk->name, clks->parent->name,
364 ((clk->parent) ?
365 clk->parent->name : "NULL"));
366 clk_reparent(clk, clks->parent);
367 };
368 found = 1;
369 }
370 }
371 }
372
373 /* This indicates a data error */
374 WARN(!found, "clock: %s: init parent: could not find regval %0x\n",
375 clk->name, r);
376
377 return;
378}
379
380/**
381 * omap2_clksel_recalc() - function ptr to pass via struct clk .recalc field
382 * @clk: struct clk *
383 *
384 * This function is intended to be called only by the clock framework.
385 * Each clksel clock should have its struct clk .recalc field set to this
386 * function. Returns the clock's current rate, based on its parent's rate
387 * and its current divisor setting in the hardware.
388 */
389unsigned long omap2_clksel_recalc(struct clk *clk)
390{
391 unsigned long rate;
392 u32 div = 0;
393
394 div = _read_divisor(clk);
395 if (div == 0)
396 return clk->rate;
397
398 rate = clk->parent->rate / div;
399
400 pr_debug("clock: %s: recalc'd rate is %ld (div %d)\n", clk->name,
401 rate, div);
402
403 return rate;
404}
405
406/**
407 * omap2_clksel_round_rate() - find rounded rate for the given clock and rate
Paul Walmsleydf791b32010-01-26 20:13:04 -0700408 * @clk: OMAP struct clk to use
409 * @target_rate: desired clock rate
410 *
Paul Walmsley435699d2010-05-18 18:40:24 -0600411 * This function is intended to be called only by the clock framework.
Paul Walmsleydf791b32010-01-26 20:13:04 -0700412 * Finds best target rate based on the source clock and possible dividers.
413 * rates. The divider array must be sorted with smallest divider first.
Paul Walmsleydf791b32010-01-26 20:13:04 -0700414 *
415 * Returns the rounded clock rate or returns 0xffffffff on error.
416 */
417long omap2_clksel_round_rate(struct clk *clk, unsigned long target_rate)
418{
419 u32 new_div;
420
421 return omap2_clksel_round_rate_div(clk, target_rate, &new_div);
422}
423
Paul Walmsleydf791b32010-01-26 20:13:04 -0700424/**
Paul Walmsley435699d2010-05-18 18:40:24 -0600425 * omap2_clksel_set_rate() - program clock rate in hardware
426 * @clk: struct clk * to program rate
427 * @rate: target rate to program
Paul Walmsleydf791b32010-01-26 20:13:04 -0700428 *
Paul Walmsley435699d2010-05-18 18:40:24 -0600429 * This function is intended to be called only by the clock framework.
430 * Program @clk's rate to @rate in the hardware. The clock can be
431 * either enabled or disabled when this happens, although if the clock
432 * is enabled, some downstream devices may glitch or behave
433 * unpredictably when the clock rate is changed - this depends on the
434 * hardware. This function does not currently check the usecount of
435 * the clock, so if multiple drivers are using the clock, and the rate
436 * is changed, they will all be affected without any notification.
437 * Returns -EINVAL upon error, or 0 upon success.
Paul Walmsleydf791b32010-01-26 20:13:04 -0700438 */
Paul Walmsleydf791b32010-01-26 20:13:04 -0700439int omap2_clksel_set_rate(struct clk *clk, unsigned long rate)
440{
Paul Walmsley435699d2010-05-18 18:40:24 -0600441 u32 field_val, validrate, new_div = 0;
Paul Walmsleydf791b32010-01-26 20:13:04 -0700442
Paul Walmsley435699d2010-05-18 18:40:24 -0600443 if (!clk->clksel || !clk->clksel_mask)
Paul Walmsleydf791b32010-01-26 20:13:04 -0700444 return -EINVAL;
445
446 validrate = omap2_clksel_round_rate_div(clk, rate, &new_div);
447 if (validrate != rate)
448 return -EINVAL;
449
Paul Walmsley435699d2010-05-18 18:40:24 -0600450 field_val = _divisor_to_clksel(clk, new_div);
Paul Walmsleydf791b32010-01-26 20:13:04 -0700451 if (field_val == ~0)
452 return -EINVAL;
453
Paul Walmsley435699d2010-05-18 18:40:24 -0600454 _write_clksel_reg(clk, field_val);
Paul Walmsleydf791b32010-01-26 20:13:04 -0700455
456 clk->rate = clk->parent->rate / new_div;
457
Paul Walmsley435699d2010-05-18 18:40:24 -0600458 pr_debug("clock: %s: set rate to %ld\n", clk->name, clk->rate);
459
Paul Walmsleydf791b32010-01-26 20:13:04 -0700460 return 0;
461}
462
Paul Walmsley435699d2010-05-18 18:40:24 -0600463/*
464 * Clksel parent setting function - not passed in struct clk function
465 * pointer - instead, the OMAP clock code currently assumes that any
466 * parent-setting clock is a clksel clock, and calls
467 * omap2_clksel_set_parent() by default
468 */
469
470/**
471 * omap2_clksel_set_parent() - change a clock's parent clock
472 * @clk: struct clk * of the child clock
473 * @new_parent: struct clk * of the new parent clock
474 *
475 * This function is intended to be called only by the clock framework.
476 * Change the parent clock of clock @clk to @new_parent. This is
477 * intended to be used while @clk is disabled. This function does not
478 * currently check the usecount of the clock, so if multiple drivers
479 * are using the clock, and the parent is changed, they will all be
480 * affected without any notification. Returns -EINVAL upon error, or
481 * 0 upon success.
482 */
Paul Walmsleydf791b32010-01-26 20:13:04 -0700483int omap2_clksel_set_parent(struct clk *clk, struct clk *new_parent)
484{
Paul Walmsley435699d2010-05-18 18:40:24 -0600485 u32 field_val = 0;
486 u32 parent_div;
Paul Walmsleydf791b32010-01-26 20:13:04 -0700487
Paul Walmsleyd74b4942010-05-18 18:40:24 -0600488 if (!clk->clksel || !clk->clksel_mask)
Paul Walmsleydf791b32010-01-26 20:13:04 -0700489 return -EINVAL;
490
Paul Walmsley435699d2010-05-18 18:40:24 -0600491 parent_div = _get_div_and_fieldval(new_parent, clk, &field_val);
Paul Walmsleydf791b32010-01-26 20:13:04 -0700492 if (!parent_div)
493 return -EINVAL;
494
Paul Walmsley435699d2010-05-18 18:40:24 -0600495 _write_clksel_reg(clk, field_val);
Paul Walmsleydf791b32010-01-26 20:13:04 -0700496
Paul Walmsleydf791b32010-01-26 20:13:04 -0700497 clk_reparent(clk, new_parent);
498
499 /* CLKSEL clocks follow their parents' rates, divided by a divisor */
500 clk->rate = new_parent->rate;
501
502 if (parent_div > 0)
503 clk->rate /= parent_div;
504
Paul Walmsley435699d2010-05-18 18:40:24 -0600505 pr_debug("clock: %s: set parent to %s (new rate %ld)\n",
Paul Walmsleydf791b32010-01-26 20:13:04 -0700506 clk->name, clk->parent->name, clk->rate);
507
508 return 0;
509}