xref: /freebsd/sys/arm/freescale/imx/imx6_anatop.c (revision 0572ccaa4543b0abef8ef81e384c1d04de9f3da1)
1 /*-
2  * Copyright (c) 2013 Ian Lepore <ian@freebsd.org>
3  * Copyright (c) 2014 Steven Lawrance <stl@koffein.net>
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25  * SUCH DAMAGE.
26  */
27 
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD$");
30 
31 /*
32  * Analog PLL and power regulator driver for Freescale i.MX6 family of SoCs.
33  * Also, temperature montoring and cpu frequency control.  It was Freescale who
34  * kitchen-sinked this device, not us. :)
35  *
36  * We don't really do anything with analog PLLs, but the registers for
37  * controlling them belong to the same block as the power regulator registers.
38  * Since the newbus hierarchy makes it hard for anyone other than us to get at
39  * them, we just export a couple public functions to allow the imx6 CCM clock
40  * driver to read and write those registers.
41  *
42  * We also don't do anything about power regulation yet, but when the need
43  * arises, this would be the place for that code to live.
44  *
45  * I have no idea where the "anatop" name comes from.  It's in the standard DTS
46  * source describing i.MX6 SoCs, and in the linux and u-boot code which comes
47  * from Freescale, but it's not in the SoC manual.
48  *
49  * Note that temperature values throughout this code are handled in two types of
50  * units.  Items with '_cnt' in the name use the hardware temperature count
51  * units (higher counts are lower temperatures).  Items with '_val' in the name
52  * are deci-Celcius, which are converted to/from deci-Kelvins in the sysctl
53  * handlers (dK is the standard unit for temperature in sysctl).
54  */
55 
56 #include <sys/param.h>
57 #include <sys/systm.h>
58 #include <sys/callout.h>
59 #include <sys/kernel.h>
60 #include <sys/limits.h>
61 #include <sys/sysctl.h>
62 #include <sys/module.h>
63 #include <sys/bus.h>
64 #include <sys/rman.h>
65 
66 #include <dev/ofw/ofw_bus.h>
67 #include <dev/ofw/ofw_bus_subr.h>
68 
69 #include <machine/bus.h>
70 #include <machine/fdt.h>
71 
72 #include <arm/arm/mpcore_timervar.h>
73 #include <arm/freescale/fsl_ocotpreg.h>
74 #include <arm/freescale/fsl_ocotpvar.h>
75 #include <arm/freescale/imx/imx6_anatopreg.h>
76 #include <arm/freescale/imx/imx6_anatopvar.h>
77 
78 static SYSCTL_NODE(_hw, OID_AUTO, imx6, CTLFLAG_RW, NULL, "i.MX6 container");
79 
80 static struct resource_spec imx6_anatop_spec[] = {
81 	{ SYS_RES_MEMORY,	0,	RF_ACTIVE },
82 	{ SYS_RES_IRQ,		0,	RF_ACTIVE },
83 	{ -1, 0 }
84 };
85 #define	MEMRES	0
86 #define	IRQRES	1
87 
88 struct imx6_anatop_softc {
89 	device_t	dev;
90 	struct resource	*res[2];
91 	uint32_t	cpu_curmhz;
92 	uint32_t	cpu_curmv;
93 	uint32_t	cpu_minmhz;
94 	uint32_t	cpu_minmv;
95 	uint32_t	cpu_maxmhz;
96 	uint32_t	cpu_maxmv;
97 	uint32_t	cpu_maxmhz_hw;
98 	boolean_t	cpu_overclock_enable;
99 	uint32_t	refosc_mhz;
100 	void		*temp_intrhand;
101 	uint32_t	temp_high_val;
102 	uint32_t	temp_high_cnt;
103 	uint32_t	temp_last_cnt;
104 	uint32_t	temp_room_cnt;
105 	struct callout	temp_throttle_callout;
106 	sbintime_t	temp_throttle_delay;
107 	uint32_t	temp_throttle_reset_cnt;
108 	uint32_t	temp_throttle_trigger_cnt;
109 	uint32_t	temp_throttle_val;
110 };
111 
112 static struct imx6_anatop_softc *imx6_anatop_sc;
113 
114 /*
115  * Table of "operating points".
116  * These are combinations of frequency and voltage blessed by Freescale.
117  */
118 static struct oppt {
119 	uint32_t	mhz;
120 	uint32_t	mv;
121 } imx6_oppt_table[] = {
122 /*      { 396,	 925},  XXX: need functional ccm code for this speed */
123 	{ 792,	1150},
124 	{ 852,	1225},
125 	{ 996,	1225},
126 	{1200,	1275},
127 };
128 
129 /*
130  * Table of CPU max frequencies.  This is used to translate the max frequency
131  * value (0-3) from the ocotp CFG3 register into a mhz value that can be looked
132  * up in the operating points table.
133  */
134 static uint32_t imx6_ocotp_mhz_tab[] = {792, 852, 996, 1200};
135 
136 #define	TZ_ZEROC	2732	/* deci-Kelvin <-> deci-Celcius offset. */
137 
138 uint32_t
139 imx6_anatop_read_4(bus_size_t offset)
140 {
141 
142 	KASSERT(imx6_anatop_sc != NULL, ("imx6_anatop_read_4 sc NULL"));
143 
144 	return (bus_read_4(imx6_anatop_sc->res[MEMRES], offset));
145 }
146 
147 void
148 imx6_anatop_write_4(bus_size_t offset, uint32_t value)
149 {
150 
151 	KASSERT(imx6_anatop_sc != NULL, ("imx6_anatop_write_4 sc NULL"));
152 
153 	bus_write_4(imx6_anatop_sc->res[MEMRES], offset, value);
154 }
155 
156 static void
157 vdd_set(struct imx6_anatop_softc *sc, int mv)
158 {
159 	int newtarg, oldtarg;
160 	uint32_t delay, pmureg;
161 	static boolean_t init_done = false;
162 
163 	/*
164 	 * The datasheet says VDD_PU and VDD_SOC must be equal, and VDD_ARM
165 	 * can't be more than 50mV above or 200mV below them.  For now to keep
166 	 * things simple we set all three to the same value.
167 	 */
168 
169 	pmureg = imx6_anatop_read_4(IMX6_ANALOG_PMU_REG_CORE);
170 	oldtarg = pmureg & IMX6_ANALOG_PMU_REG0_TARG_MASK;
171 
172 	/* Convert mV to target value.  Clamp target to valid range. */
173 	if (mv < 725)
174 		newtarg = 0x00;
175 	else if (mv > 1450)
176 		newtarg = 0x1F;
177 	else
178 		newtarg = (mv - 700) / 25;
179 
180 	/*
181 	 * The first time through the 3 voltages might not be equal so use a
182 	 * long conservative delay.  After that we need to delay 3uS for every
183 	 * 25mV step upward.  No need to delay at all when lowering.
184 	 */
185 	if (init_done) {
186 		if (newtarg == oldtarg)
187 			return;
188 		else if (newtarg > oldtarg)
189 			delay = (newtarg - oldtarg) * 3;
190 		else
191 			delay = 0;
192 	} else {
193 		delay = 700 / 25 * 3;
194 		init_done = true;
195 	}
196 
197 	/*
198 	 * Make the change and wait for it to take effect.
199 	 */
200 	pmureg &= ~(IMX6_ANALOG_PMU_REG0_TARG_MASK |
201 	    IMX6_ANALOG_PMU_REG1_TARG_MASK |
202 	    IMX6_ANALOG_PMU_REG2_TARG_MASK);
203 
204 	pmureg |= newtarg << IMX6_ANALOG_PMU_REG0_TARG_SHIFT;
205 	pmureg |= newtarg << IMX6_ANALOG_PMU_REG1_TARG_SHIFT;
206 	pmureg |= newtarg << IMX6_ANALOG_PMU_REG2_TARG_SHIFT;
207 
208 	imx6_anatop_write_4(IMX6_ANALOG_PMU_REG_CORE, pmureg);
209 	DELAY(delay);
210 	sc->cpu_curmv = newtarg * 25 + 700;
211 }
212 
213 static inline uint32_t
214 cpufreq_mhz_from_div(struct imx6_anatop_softc *sc, uint32_t div)
215 {
216 
217 	return (sc->refosc_mhz * (div / 2));
218 }
219 
220 static inline uint32_t
221 cpufreq_mhz_to_div(struct imx6_anatop_softc *sc, uint32_t cpu_mhz)
222 {
223 
224 	return (cpu_mhz / (sc->refosc_mhz / 2));
225 }
226 
227 static inline uint32_t
228 cpufreq_actual_mhz(struct imx6_anatop_softc *sc, uint32_t cpu_mhz)
229 {
230 
231 	return (cpufreq_mhz_from_div(sc, cpufreq_mhz_to_div(sc, cpu_mhz)));
232 }
233 
234 static struct oppt *
235 cpufreq_nearest_oppt(struct imx6_anatop_softc *sc, uint32_t cpu_newmhz)
236 {
237 	int d, diff, i, nearest;
238 
239 	if (cpu_newmhz > sc->cpu_maxmhz_hw && !sc->cpu_overclock_enable)
240 		cpu_newmhz = sc->cpu_maxmhz_hw;
241 
242 	diff = INT_MAX;
243 	nearest = 0;
244 	for (i = 0; i < nitems(imx6_oppt_table); ++i) {
245 		d = abs((int)cpu_newmhz - (int)imx6_oppt_table[i].mhz);
246 		if (diff > d) {
247 			diff = d;
248 			nearest = i;
249 		}
250 	}
251 	return (&imx6_oppt_table[nearest]);
252 }
253 
254 static void
255 cpufreq_set_clock(struct imx6_anatop_softc * sc, struct oppt *op)
256 {
257 	uint32_t timeout, wrk32;
258 
259 	/* If increasing the frequency, we must first increase the voltage. */
260 	if (op->mhz > sc->cpu_curmhz) {
261 		vdd_set(sc, op->mv);
262 	}
263 
264 	/*
265 	 * I can't find a documented procedure for changing the ARM PLL divisor,
266 	 * but some trial and error came up with this:
267 	 *  - Set the bypass clock source to REF_CLK_24M (source #0).
268 	 *  - Set the PLL into bypass mode; cpu should now be running at 24mhz.
269 	 *  - Change the divisor.
270 	 *  - Wait for the LOCK bit to come on; it takes ~50 loop iterations.
271 	 *  - Turn off bypass mode; cpu should now be running at the new speed.
272 	 */
273 	imx6_anatop_write_4(IMX6_ANALOG_CCM_PLL_ARM_CLR,
274 	    IMX6_ANALOG_CCM_PLL_ARM_CLK_SRC_MASK);
275 	imx6_anatop_write_4(IMX6_ANALOG_CCM_PLL_ARM_SET,
276 	    IMX6_ANALOG_CCM_PLL_ARM_BYPASS);
277 
278 	wrk32 = imx6_anatop_read_4(IMX6_ANALOG_CCM_PLL_ARM);
279 	wrk32 &= ~IMX6_ANALOG_CCM_PLL_ARM_DIV_MASK;
280 	wrk32 |= cpufreq_mhz_to_div(sc, op->mhz);
281 	imx6_anatop_write_4(IMX6_ANALOG_CCM_PLL_ARM, wrk32);
282 
283 	timeout = 10000;
284 	while ((imx6_anatop_read_4(IMX6_ANALOG_CCM_PLL_ARM) &
285 	    IMX6_ANALOG_CCM_PLL_ARM_LOCK) == 0)
286 		if (--timeout == 0)
287 			panic("imx6_set_cpu_clock(): PLL never locked");
288 
289 	imx6_anatop_write_4(IMX6_ANALOG_CCM_PLL_ARM_CLR,
290 	    IMX6_ANALOG_CCM_PLL_ARM_BYPASS);
291 
292 	/* If lowering the frequency, it is now safe to lower the voltage. */
293 	if (op->mhz < sc->cpu_curmhz)
294 		vdd_set(sc, op->mv);
295 	sc->cpu_curmhz = op->mhz;
296 
297 	/* Tell the mpcore timer that its frequency has changed. */
298         arm_tmr_change_frequency(
299 	    cpufreq_actual_mhz(sc, sc->cpu_curmhz) * 1000000 / 2);
300 }
301 
302 static int
303 cpufreq_sysctl_minmhz(SYSCTL_HANDLER_ARGS)
304 {
305 	struct imx6_anatop_softc *sc;
306 	struct oppt * op;
307 	uint32_t temp;
308 	int err;
309 
310 	sc = arg1;
311 
312 	temp = sc->cpu_minmhz;
313 	err = sysctl_handle_int(oidp, &temp, 0, req);
314 	if (err != 0 || req->newptr == NULL)
315 		return (err);
316 
317 	op = cpufreq_nearest_oppt(sc, temp);
318 	if (op->mhz > sc->cpu_maxmhz)
319 		return (ERANGE);
320 	else if (op->mhz == sc->cpu_minmhz)
321 		return (0);
322 
323 	/*
324 	 * Value changed, update softc.  If the new min is higher than the
325 	 * current speed, raise the current speed to match.
326 	 */
327 	sc->cpu_minmhz = op->mhz;
328 	if (sc->cpu_minmhz > sc->cpu_curmhz) {
329 		cpufreq_set_clock(sc, op);
330 	}
331 	return (err);
332 }
333 
334 static int
335 cpufreq_sysctl_maxmhz(SYSCTL_HANDLER_ARGS)
336 {
337 	struct imx6_anatop_softc *sc;
338 	struct oppt * op;
339 	uint32_t temp;
340 	int err;
341 
342 	sc = arg1;
343 
344 	temp = sc->cpu_maxmhz;
345 	err = sysctl_handle_int(oidp, &temp, 0, req);
346 	if (err != 0 || req->newptr == NULL)
347 		return (err);
348 
349 	op = cpufreq_nearest_oppt(sc, temp);
350 	if (op->mhz < sc->cpu_minmhz)
351 		return (ERANGE);
352 	else if (op->mhz == sc->cpu_maxmhz)
353 		return (0);
354 
355 	/*
356 	 *  Value changed, update softc and hardware.  The hardware update is
357 	 *  unconditional.  We always try to run at max speed, so any change of
358 	 *  the max means we need to change the current speed too, regardless of
359 	 *  whether it is higher or lower than the old max.
360 	 */
361 	sc->cpu_maxmhz = op->mhz;
362 	cpufreq_set_clock(sc, op);
363 
364 	return (err);
365 }
366 
367 static void
368 cpufreq_initialize(struct imx6_anatop_softc *sc)
369 {
370 	uint32_t cfg3speed;
371 	struct oppt * op;
372 
373 	SYSCTL_ADD_INT(NULL, SYSCTL_STATIC_CHILDREN(_hw_imx6),
374 	    OID_AUTO, "cpu_mhz", CTLFLAG_RD, &sc->cpu_curmhz, 0,
375 	    "CPU frequency");
376 
377 	SYSCTL_ADD_PROC(NULL, SYSCTL_STATIC_CHILDREN(_hw_imx6),
378 	    OID_AUTO, "cpu_minmhz", CTLTYPE_INT | CTLFLAG_RWTUN, sc, 0,
379 	    cpufreq_sysctl_minmhz, "IU", "Minimum CPU frequency");
380 
381 	SYSCTL_ADD_PROC(NULL, SYSCTL_STATIC_CHILDREN(_hw_imx6),
382 	    OID_AUTO, "cpu_maxmhz", CTLTYPE_INT | CTLFLAG_RWTUN, sc, 0,
383 	    cpufreq_sysctl_maxmhz, "IU", "Maximum CPU frequency");
384 
385 	SYSCTL_ADD_INT(NULL, SYSCTL_STATIC_CHILDREN(_hw_imx6),
386 	    OID_AUTO, "cpu_maxmhz_hw", CTLFLAG_RD, &sc->cpu_maxmhz_hw, 0,
387 	    "Maximum CPU frequency allowed by hardware");
388 
389 	SYSCTL_ADD_INT(NULL, SYSCTL_STATIC_CHILDREN(_hw_imx6),
390 	    OID_AUTO, "cpu_overclock_enable", CTLFLAG_RWTUN,
391 	    &sc->cpu_overclock_enable, 0,
392 	    "Allow setting CPU frequency higher than cpu_maxmhz_hw");
393 
394 	/*
395 	 * XXX 24mhz shouldn't be hard-coded, should get this from imx6_ccm
396 	 * (even though in the real world it will always be 24mhz).  Oh wait a
397 	 * sec, I never wrote imx6_ccm.
398 	 */
399 	sc->refosc_mhz = 24;
400 
401 	/*
402 	 * Get the maximum speed this cpu can be set to.  The values in the
403 	 * OCOTP CFG3 register are not documented in the reference manual.
404 	 * The following info was in an archived email found via web search:
405 	 *   - 2b'11: 1200000000Hz;
406 	 *   - 2b'10: 996000000Hz;
407 	 *   - 2b'01: 852000000Hz; -- i.MX6Q Only, exclusive with 996MHz.
408 	 *   - 2b'00: 792000000Hz;
409 	 * The default hardware max speed can be overridden by a tunable.
410 	 */
411 	cfg3speed = (fsl_ocotp_read_4(FSL_OCOTP_CFG3) &
412 	    FSL_OCOTP_CFG3_SPEED_MASK) >> FSL_OCOTP_CFG3_SPEED_SHIFT;
413 	sc->cpu_maxmhz_hw = imx6_ocotp_mhz_tab[cfg3speed];
414 	sc->cpu_maxmhz = sc->cpu_maxmhz_hw;
415 
416 	TUNABLE_INT_FETCH("hw.imx6.cpu_overclock_enable",
417 	    &sc->cpu_overclock_enable);
418 
419 	TUNABLE_INT_FETCH("hw.imx6.cpu_minmhz", &sc->cpu_minmhz);
420 	op = cpufreq_nearest_oppt(sc, sc->cpu_minmhz);
421 	sc->cpu_minmhz = op->mhz;
422 	sc->cpu_minmv = op->mv;
423 
424 	TUNABLE_INT_FETCH("hw.imx6.cpu_maxmhz", &sc->cpu_maxmhz);
425 	op = cpufreq_nearest_oppt(sc, sc->cpu_maxmhz);
426 	sc->cpu_maxmhz = op->mhz;
427 	sc->cpu_maxmv = op->mv;
428 
429 	/*
430 	 * Set the CPU to maximum speed.
431 	 *
432 	 * We won't have thermal throttling until interrupts are enabled, but we
433 	 * want to run at full speed through all the device init stuff.  This
434 	 * basically assumes that a single core can't overheat before interrupts
435 	 * are enabled; empirical testing shows that to be a safe assumption.
436 	 */
437 	cpufreq_set_clock(sc, op);
438 }
439 
440 static inline uint32_t
441 temp_from_count(struct imx6_anatop_softc *sc, uint32_t count)
442 {
443 
444 	return (((sc->temp_high_val - (count - sc->temp_high_cnt) *
445 	    (sc->temp_high_val - 250) /
446 	    (sc->temp_room_cnt - sc->temp_high_cnt))));
447 }
448 
449 static inline uint32_t
450 temp_to_count(struct imx6_anatop_softc *sc, uint32_t temp)
451 {
452 
453 	return ((sc->temp_room_cnt - sc->temp_high_cnt) *
454 	    (sc->temp_high_val - temp) / (sc->temp_high_val - 250) +
455 	    sc->temp_high_cnt);
456 }
457 
458 static void
459 temp_update_count(struct imx6_anatop_softc *sc)
460 {
461 	uint32_t val;
462 
463 	val = imx6_anatop_read_4(IMX6_ANALOG_TEMPMON_TEMPSENSE0);
464 	if (!(val & IMX6_ANALOG_TEMPMON_TEMPSENSE0_VALID))
465 		return;
466 	sc->temp_last_cnt =
467 	    (val & IMX6_ANALOG_TEMPMON_TEMPSENSE0_TEMP_CNT_MASK) >>
468 	    IMX6_ANALOG_TEMPMON_TEMPSENSE0_TEMP_CNT_SHIFT;
469 }
470 
471 static int
472 temp_sysctl_handler(SYSCTL_HANDLER_ARGS)
473 {
474 	struct imx6_anatop_softc *sc = arg1;
475 	uint32_t t;
476 
477 	temp_update_count(sc);
478 
479 	t = temp_from_count(sc, sc->temp_last_cnt) + TZ_ZEROC;
480 
481 	return (sysctl_handle_int(oidp, &t, 0, req));
482 }
483 
484 static int
485 temp_throttle_sysctl_handler(SYSCTL_HANDLER_ARGS)
486 {
487 	struct imx6_anatop_softc *sc = arg1;
488 	int err;
489 	uint32_t temp;
490 
491 	temp = sc->temp_throttle_val + TZ_ZEROC;
492 	err = sysctl_handle_int(oidp, &temp, 0, req);
493 	if (temp < TZ_ZEROC)
494 		return (ERANGE);
495 	temp -= TZ_ZEROC;
496 	if (err != 0 || req->newptr == NULL || temp == sc->temp_throttle_val)
497 		return (err);
498 
499 	/* Value changed, update counts in softc and hardware. */
500 	sc->temp_throttle_val = temp;
501 	sc->temp_throttle_trigger_cnt = temp_to_count(sc, sc->temp_throttle_val);
502 	sc->temp_throttle_reset_cnt = temp_to_count(sc, sc->temp_throttle_val - 100);
503 	imx6_anatop_write_4(IMX6_ANALOG_TEMPMON_TEMPSENSE0_CLR,
504 	    IMX6_ANALOG_TEMPMON_TEMPSENSE0_ALARM_MASK);
505 	imx6_anatop_write_4(IMX6_ANALOG_TEMPMON_TEMPSENSE0_SET,
506 	    (sc->temp_throttle_trigger_cnt <<
507 	     IMX6_ANALOG_TEMPMON_TEMPSENSE0_ALARM_SHIFT));
508 	return (err);
509 }
510 
511 static void
512 tempmon_gofast(struct imx6_anatop_softc *sc)
513 {
514 
515 	if (sc->cpu_curmhz < sc->cpu_maxmhz) {
516 		cpufreq_set_clock(sc, cpufreq_nearest_oppt(sc, sc->cpu_maxmhz));
517 	}
518 }
519 
520 static void
521 tempmon_goslow(struct imx6_anatop_softc *sc)
522 {
523 
524 	if (sc->cpu_curmhz > sc->cpu_minmhz) {
525 		cpufreq_set_clock(sc, cpufreq_nearest_oppt(sc, sc->cpu_minmhz));
526 	}
527 }
528 
529 static int
530 tempmon_intr(void *arg)
531 {
532 	struct imx6_anatop_softc *sc = arg;
533 
534 	/*
535 	 * XXX Note that this code doesn't currently run (for some mysterious
536 	 * reason we just never get an interrupt), so the real monitoring is
537 	 * done by tempmon_throttle_check().
538 	 */
539 	tempmon_goslow(sc);
540 	/* XXX Schedule callout to speed back up eventually. */
541 	return (FILTER_HANDLED);
542 }
543 
544 static void
545 tempmon_throttle_check(void *arg)
546 {
547 	struct imx6_anatop_softc *sc = arg;
548 
549 	/* Lower counts are higher temperatures. */
550 	if (sc->temp_last_cnt < sc->temp_throttle_trigger_cnt)
551 		tempmon_goslow(sc);
552 	else if (sc->temp_last_cnt > (sc->temp_throttle_reset_cnt))
553 		tempmon_gofast(sc);
554 
555 	callout_reset_sbt(&sc->temp_throttle_callout, sc->temp_throttle_delay,
556 		0, tempmon_throttle_check, sc, 0);
557 
558 }
559 
560 static void
561 initialize_tempmon(struct imx6_anatop_softc *sc)
562 {
563 	uint32_t cal;
564 	struct sysctl_ctx_list *ctx;
565 
566 	/*
567 	 * Fetch calibration data: a sensor count at room temperature (25C),
568 	 * a sensor count at a high temperature, and that temperature
569 	 */
570 	cal = fsl_ocotp_read_4(FSL_OCOTP_ANA1);
571 	sc->temp_room_cnt = (cal & 0xFFF00000) >> 20;
572 	sc->temp_high_cnt = (cal & 0x000FFF00) >> 8;
573 	sc->temp_high_val = (cal & 0x000000FF) * 10;
574 
575 	/*
576 	 * Throttle to a lower cpu freq at 10C below the "hot" temperature, and
577 	 * reset back to max cpu freq at 5C below the trigger.
578 	 */
579 	sc->temp_throttle_val = sc->temp_high_val - 100;
580 	sc->temp_throttle_trigger_cnt =
581 	    temp_to_count(sc, sc->temp_throttle_val);
582 	sc->temp_throttle_reset_cnt =
583 	    temp_to_count(sc, sc->temp_throttle_val - 50);
584 
585 	/*
586 	 * Set the sensor to sample automatically at 16Hz (32.768KHz/0x800), set
587 	 * the throttle count, and begin making measurements.
588 	 */
589 	imx6_anatop_write_4(IMX6_ANALOG_TEMPMON_TEMPSENSE1, 0x0800);
590 	imx6_anatop_write_4(IMX6_ANALOG_TEMPMON_TEMPSENSE0,
591 	    (sc->temp_throttle_trigger_cnt <<
592 	    IMX6_ANALOG_TEMPMON_TEMPSENSE0_ALARM_SHIFT) |
593 	    IMX6_ANALOG_TEMPMON_TEMPSENSE0_MEASURE);
594 
595 	/*
596 	 * XXX Note that the alarm-interrupt feature isn't working yet, so
597 	 * we'll use a callout handler to check at 10Hz.  Make sure we have an
598 	 * initial temperature reading before starting up the callouts so we
599 	 * don't get a bogus reading of zero.
600 	 */
601 	while (sc->temp_last_cnt == 0)
602 		temp_update_count(sc);
603 	sc->temp_throttle_delay = 100 * SBT_1MS;
604 	callout_init(&sc->temp_throttle_callout, 0);
605 	callout_reset_sbt(&sc->temp_throttle_callout, sc->temp_throttle_delay,
606 	    0, tempmon_throttle_check, sc, 0);
607 
608 	ctx = device_get_sysctl_ctx(sc->dev);
609 	SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(device_get_sysctl_tree(sc->dev)),
610 	    OID_AUTO, "temperature", CTLTYPE_INT | CTLFLAG_RD, sc, 0,
611 	    temp_sysctl_handler, "IK", "Current die temperature");
612 	SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(device_get_sysctl_tree(sc->dev)),
613 	    OID_AUTO, "throttle_temperature", CTLTYPE_INT | CTLFLAG_RW, sc,
614 	    0, temp_throttle_sysctl_handler, "IK",
615 	    "Throttle CPU when exceeding this temperature");
616 }
617 
618 static int
619 imx6_anatop_detach(device_t dev)
620 {
621 
622 	return (EBUSY);
623 }
624 
625 static int
626 imx6_anatop_attach(device_t dev)
627 {
628 	struct imx6_anatop_softc *sc;
629 	int err;
630 
631 	sc = device_get_softc(dev);
632 	sc->dev = dev;
633 
634 	/* Allocate bus_space resources. */
635 	if (bus_alloc_resources(dev, imx6_anatop_spec, sc->res)) {
636 		device_printf(dev, "Cannot allocate resources\n");
637 		err = ENXIO;
638 		goto out;
639 	}
640 
641 	err = bus_setup_intr(dev, sc->res[IRQRES], INTR_TYPE_MISC | INTR_MPSAFE,
642 	    tempmon_intr, NULL, sc, &sc->temp_intrhand);
643 	if (err != 0)
644 		goto out;
645 
646 	SYSCTL_ADD_UINT(device_get_sysctl_ctx(sc->dev),
647 	    SYSCTL_CHILDREN(device_get_sysctl_tree(sc->dev)),
648 	    OID_AUTO, "cpu_voltage", CTLFLAG_RD,
649 	    &sc->cpu_curmv, 0, "Current CPU voltage in millivolts");
650 
651 	imx6_anatop_sc = sc;
652 
653 	/*
654 	 * Other code seen on the net sets this SELFBIASOFF flag around the same
655 	 * time the temperature sensor is set up, although it's unclear how the
656 	 * two are related (if at all).
657 	 */
658 	imx6_anatop_write_4(IMX6_ANALOG_PMU_MISC0_SET,
659 	    IMX6_ANALOG_PMU_MISC0_SELFBIASOFF);
660 
661 	cpufreq_initialize(sc);
662 	initialize_tempmon(sc);
663 
664 	if (bootverbose) {
665 		device_printf(sc->dev, "CPU %uMHz @ %umV\n", sc->cpu_curmhz,
666 		    sc->cpu_curmv);
667 	}
668 	err = 0;
669 
670 out:
671 
672 	if (err != 0) {
673 		bus_release_resources(dev, imx6_anatop_spec, sc->res);
674 	}
675 
676 	return (err);
677 }
678 
679 static int
680 imx6_anatop_probe(device_t dev)
681 {
682 
683 	if (!ofw_bus_status_okay(dev))
684 		return (ENXIO);
685 
686 	if (ofw_bus_is_compatible(dev, "fsl,imx6q-anatop") == 0)
687 		return (ENXIO);
688 
689 	device_set_desc(dev, "Freescale i.MX6 Analog PLLs and Power");
690 
691 	return (BUS_PROBE_DEFAULT);
692 }
693 
694 uint32_t
695 imx6_get_cpu_clock()
696 {
697 	uint32_t div;
698 
699 	div = imx6_anatop_read_4(IMX6_ANALOG_CCM_PLL_ARM) &
700 	    IMX6_ANALOG_CCM_PLL_ARM_DIV_MASK;
701 	return (cpufreq_mhz_from_div(imx6_anatop_sc, div));
702 }
703 
704 static device_method_t imx6_anatop_methods[] = {
705 	/* Device interface */
706 	DEVMETHOD(device_probe,  imx6_anatop_probe),
707 	DEVMETHOD(device_attach, imx6_anatop_attach),
708 	DEVMETHOD(device_detach, imx6_anatop_detach),
709 
710 	DEVMETHOD_END
711 };
712 
713 static driver_t imx6_anatop_driver = {
714 	"imx6_anatop",
715 	imx6_anatop_methods,
716 	sizeof(struct imx6_anatop_softc)
717 };
718 
719 static devclass_t imx6_anatop_devclass;
720 
721 DRIVER_MODULE(imx6_anatop, simplebus, imx6_anatop_driver, imx6_anatop_devclass, 0, 0);
722 
723