xref: /freebsd/sys/arm/freescale/imx/imx6_anatop.c (revision dda5b39711dab90ae1c5624bdd6ff7453177df31)
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/sysctl.h>
61 #include <sys/module.h>
62 #include <sys/bus.h>
63 #include <sys/rman.h>
64 
65 #include <dev/ofw/ofw_bus.h>
66 #include <dev/ofw/ofw_bus_subr.h>
67 
68 #include <machine/bus.h>
69 #include <machine/fdt.h>
70 
71 #include <arm/freescale/fsl_ocotpreg.h>
72 #include <arm/freescale/fsl_ocotpvar.h>
73 #include <arm/freescale/imx/imx6_anatopreg.h>
74 #include <arm/freescale/imx/imx6_anatopvar.h>
75 
76 static struct resource_spec imx6_anatop_spec[] = {
77 	{ SYS_RES_MEMORY,	0,	RF_ACTIVE },
78 	{ SYS_RES_IRQ,		0,	RF_ACTIVE },
79 	{ -1, 0 }
80 };
81 #define	MEMRES	0
82 #define	IRQRES	1
83 
84 struct imx6_anatop_softc {
85 	device_t	dev;
86 	struct resource	*res[2];
87 	uint32_t	cpu_curhz;
88 	uint32_t	cpu_curmhz;
89 	uint32_t	cpu_curmv;
90 	uint32_t	cpu_minhz;
91 	uint32_t	cpu_minmv;
92 	uint32_t	cpu_maxhz;
93 	uint32_t	cpu_maxmv;
94 	uint32_t	refosc_hz;
95 	void		*temp_intrhand;
96 	uint32_t	temp_high_val;
97 	uint32_t	temp_high_cnt;
98 	uint32_t	temp_last_cnt;
99 	uint32_t	temp_room_cnt;
100 	struct callout	temp_throttle_callout;
101 	sbintime_t	temp_throttle_delay;
102 	uint32_t	temp_throttle_reset_cnt;
103 	uint32_t	temp_throttle_trigger_cnt;
104 	uint32_t	temp_throttle_val;
105 };
106 
107 static struct imx6_anatop_softc *imx6_anatop_sc;
108 
109 /*
110  * Tables of CPU max frequencies and corresponding voltages.  This is indexed by
111  * the max frequency value (0-3) from the ocotp CFG3 register.
112  */
113 static uint32_t imx6_cpu_maxhz_tab[] = {
114 	 792000000, 852000000, 996000000, 1200000000
115 };
116 static uint32_t imx6_cpu_millivolt_tab[] = {
117 	1150, 1225, 1225, 1275
118 };
119 
120 #define	TZ_ZEROC	2732	/* deci-Kelvin <-> deci-Celcius offset. */
121 
122 uint32_t
123 imx6_anatop_read_4(bus_size_t offset)
124 {
125 
126 	KASSERT(imx6_anatop_sc != NULL, ("imx6_anatop_read_4 sc NULL"));
127 
128 	return (bus_read_4(imx6_anatop_sc->res[MEMRES], offset));
129 }
130 
131 void
132 imx6_anatop_write_4(bus_size_t offset, uint32_t value)
133 {
134 
135 	KASSERT(imx6_anatop_sc != NULL, ("imx6_anatop_write_4 sc NULL"));
136 
137 	bus_write_4(imx6_anatop_sc->res[MEMRES], offset, value);
138 }
139 
140 static void
141 vdd_set(struct imx6_anatop_softc *sc, int mv)
142 {
143 	int newtarg, oldtarg;
144 	uint32_t delay, pmureg;
145 	static boolean_t init_done = false;
146 
147 	/*
148 	 * The datasheet says VDD_PU and VDD_SOC must be equal, and VDD_ARM
149 	 * can't be more than 50mV above or 200mV below them.  For now to keep
150 	 * things simple we set all three to the same value.
151 	 */
152 
153 	pmureg = imx6_anatop_read_4(IMX6_ANALOG_PMU_REG_CORE);
154 	oldtarg = pmureg & IMX6_ANALOG_PMU_REG0_TARG_MASK;
155 
156 	/* Convert mV to target value.  Clamp target to valid range. */
157 	if (mv < 725)
158 		newtarg = 0x00;
159 	else if (mv > 1450)
160 		newtarg = 0x1F;
161 	else
162 		newtarg = (mv - 700) / 25;
163 
164 	/*
165 	 * The first time through the 3 voltages might not be equal so use a
166 	 * long conservative delay.  After that we need to delay 3uS for every
167 	 * 25mV step upward.  No need to delay at all when lowering.
168 	 */
169 	if (init_done) {
170 		if (newtarg == oldtarg)
171 			return;
172 		else if (newtarg > oldtarg)
173 			delay = (newtarg - oldtarg) * 3;
174 		else
175 			delay = 0;
176 	} else {
177 		delay = 700 / 25 * 3;
178 		init_done = true;
179 	}
180 
181 	/*
182 	 * Make the change and wait for it to take effect.
183 	 */
184 	pmureg &= ~(IMX6_ANALOG_PMU_REG0_TARG_MASK |
185 	    IMX6_ANALOG_PMU_REG1_TARG_MASK |
186 	    IMX6_ANALOG_PMU_REG2_TARG_MASK);
187 
188 	pmureg |= newtarg << IMX6_ANALOG_PMU_REG0_TARG_SHIFT;
189 	pmureg |= newtarg << IMX6_ANALOG_PMU_REG1_TARG_SHIFT;
190 	pmureg |= newtarg << IMX6_ANALOG_PMU_REG2_TARG_SHIFT;
191 
192 	imx6_anatop_write_4(IMX6_ANALOG_PMU_REG_CORE, pmureg);
193 	DELAY(delay);
194 	sc->cpu_curmv = newtarg * 25 + 700;
195 	device_printf(sc->dev, "voltage set to %u\n", sc->cpu_curmv);
196 }
197 
198 static inline uint32_t
199 cpufreq_hz_from_div(struct imx6_anatop_softc *sc, uint32_t div)
200 {
201 
202 	return (sc->refosc_hz * (div / 2));
203 }
204 
205 static inline uint32_t
206 cpufreq_hz_to_div(struct imx6_anatop_softc *sc, uint32_t cpu_hz)
207 {
208 
209 	return (cpu_hz / (sc->refosc_hz / 2));
210 }
211 
212 static inline uint32_t
213 cpufreq_actual_hz(struct imx6_anatop_softc *sc, uint32_t cpu_hz)
214 {
215 
216 	return (cpufreq_hz_from_div(sc, cpufreq_hz_to_div(sc, cpu_hz)));
217 }
218 
219 static void
220 cpufreq_set_clock(struct imx6_anatop_softc * sc, uint32_t cpu_newhz)
221 {
222 	uint32_t div, timeout, wrk32;
223 	const uint32_t mindiv =  54;
224 	const uint32_t maxdiv = 108;
225 
226 	/*
227 	 * Clip the requested frequency to the configured max, then clip the
228 	 * resulting divisor to the documented min/max values.
229 	 */
230 	cpu_newhz = min(cpu_newhz, sc->cpu_maxhz);
231 	div = cpufreq_hz_to_div(sc, cpu_newhz);
232 	if (div < mindiv)
233 		div = mindiv;
234 	else if (div > maxdiv)
235 		div = maxdiv;
236 	sc->cpu_curhz = cpufreq_hz_from_div(sc, div);
237 	sc->cpu_curmhz = sc->cpu_curhz / 1000000;
238 
239 	/*
240 	 * I can't find a documented procedure for changing the ARM PLL divisor,
241 	 * but some trial and error came up with this:
242 	 *  - Set the bypass clock source to REF_CLK_24M (source #0).
243 	 *  - Set the PLL into bypass mode; cpu should now be running at 24mhz.
244 	 *  - Change the divisor.
245 	 *  - Wait for the LOCK bit to come on; it takes ~50 loop iterations.
246 	 *  - Turn off bypass mode; cpu should now be running at cpu_newhz.
247 	 */
248 	imx6_anatop_write_4(IMX6_ANALOG_CCM_PLL_ARM_CLR,
249 	    IMX6_ANALOG_CCM_PLL_ARM_CLK_SRC_MASK);
250 	imx6_anatop_write_4(IMX6_ANALOG_CCM_PLL_ARM_SET,
251 	    IMX6_ANALOG_CCM_PLL_ARM_BYPASS);
252 
253 	wrk32 = imx6_anatop_read_4(IMX6_ANALOG_CCM_PLL_ARM);
254 	wrk32 &= ~IMX6_ANALOG_CCM_PLL_ARM_DIV_MASK;
255 	wrk32 |= div;
256 	imx6_anatop_write_4(IMX6_ANALOG_CCM_PLL_ARM, wrk32);
257 
258 	timeout = 10000;
259 	while ((imx6_anatop_read_4(IMX6_ANALOG_CCM_PLL_ARM) &
260 	    IMX6_ANALOG_CCM_PLL_ARM_LOCK) == 0)
261 		if (--timeout == 0)
262 			panic("imx6_set_cpu_clock(): PLL never locked");
263 
264 	imx6_anatop_write_4(IMX6_ANALOG_CCM_PLL_ARM_CLR,
265 	    IMX6_ANALOG_CCM_PLL_ARM_BYPASS);
266 }
267 
268 static void
269 cpufreq_initialize(struct imx6_anatop_softc *sc)
270 {
271 	uint32_t cfg3speed;
272 	struct sysctl_ctx_list *ctx;
273 
274 	ctx = device_get_sysctl_ctx(sc->dev);
275 	SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(device_get_sysctl_tree(sc->dev)),
276 	    OID_AUTO, "cpu_mhz", CTLFLAG_RD, &sc->cpu_curmhz, 0,
277 	    "CPU frequency in MHz");
278 
279 	/*
280 	 * XXX 24mhz shouldn't be hard-coded, should get this from imx6_ccm
281 	 * (even though in the real world it will always be 24mhz).  Oh wait a
282 	 * sec, I never wrote imx6_ccm.
283 	 */
284 	sc->refosc_hz = 24000000;
285 
286 	/*
287 	 * Get the maximum speed this cpu can be set to.  The values in the
288 	 * OCOTP CFG3 register are not documented in the reference manual.
289 	 * The following info was in an archived email found via web search:
290 	 *   - 2b'11: 1200000000Hz;
291 	 *   - 2b'10: 996000000Hz;
292 	 *   - 2b'01: 852000000Hz; -- i.MX6Q Only, exclusive with 996MHz.
293 	 *   - 2b'00: 792000000Hz;
294 	 */
295 	cfg3speed = (fsl_ocotp_read_4(FSL_OCOTP_CFG3) &
296 	    FSL_OCOTP_CFG3_SPEED_MASK) >> FSL_OCOTP_CFG3_SPEED_SHIFT;
297 
298 	sc->cpu_minhz = cpufreq_actual_hz(sc, imx6_cpu_maxhz_tab[0]);
299 	sc->cpu_minmv = imx6_cpu_millivolt_tab[0];
300 	sc->cpu_maxhz = cpufreq_actual_hz(sc, imx6_cpu_maxhz_tab[cfg3speed]);
301 	sc->cpu_maxmv = imx6_cpu_millivolt_tab[cfg3speed];
302 
303 	/*
304 	 * Set the CPU to maximum speed.
305 	 *
306 	 * We won't have thermal throttling until interrupts are enabled, but we
307 	 * want to run at full speed through all the device init stuff.  This
308 	 * basically assumes that a single core can't overheat before interrupts
309 	 * are enabled; empirical testing shows that to be a safe assumption.
310 	 */
311 	vdd_set(sc, sc->cpu_maxmv);
312 	cpufreq_set_clock(sc, sc->cpu_maxhz);
313 	device_printf(sc->dev, "CPU frequency %uMHz\n", sc->cpu_curmhz);
314 }
315 
316 static inline uint32_t
317 temp_from_count(struct imx6_anatop_softc *sc, uint32_t count)
318 {
319 
320 	return (((sc->temp_high_val - (count - sc->temp_high_cnt) *
321 	    (sc->temp_high_val - 250) /
322 	    (sc->temp_room_cnt - sc->temp_high_cnt))));
323 }
324 
325 static inline uint32_t
326 temp_to_count(struct imx6_anatop_softc *sc, uint32_t temp)
327 {
328 
329 	return ((sc->temp_room_cnt - sc->temp_high_cnt) *
330 	    (sc->temp_high_val - temp) / (sc->temp_high_val - 250) +
331 	    sc->temp_high_cnt);
332 }
333 
334 static void
335 temp_update_count(struct imx6_anatop_softc *sc)
336 {
337 	uint32_t val;
338 
339 	val = imx6_anatop_read_4(IMX6_ANALOG_TEMPMON_TEMPSENSE0);
340 	if (!(val & IMX6_ANALOG_TEMPMON_TEMPSENSE0_VALID))
341 		return;
342 	sc->temp_last_cnt =
343 	    (val & IMX6_ANALOG_TEMPMON_TEMPSENSE0_TEMP_CNT_MASK) >>
344 	    IMX6_ANALOG_TEMPMON_TEMPSENSE0_TEMP_CNT_SHIFT;
345 }
346 
347 static int
348 temp_sysctl_handler(SYSCTL_HANDLER_ARGS)
349 {
350 	struct imx6_anatop_softc *sc = arg1;
351 	uint32_t t;
352 
353 	temp_update_count(sc);
354 
355 	t = temp_from_count(sc, sc->temp_last_cnt) + TZ_ZEROC;
356 
357 	return (sysctl_handle_int(oidp, &t, 0, req));
358 }
359 
360 static int
361 temp_throttle_sysctl_handler(SYSCTL_HANDLER_ARGS)
362 {
363 	struct imx6_anatop_softc *sc = arg1;
364 	int err;
365 	uint32_t temp;
366 
367 	temp = sc->temp_throttle_val + TZ_ZEROC;
368 	err = sysctl_handle_int(oidp, &temp, 0, req);
369 	if (temp < TZ_ZEROC)
370 		return (ERANGE);
371 	temp -= TZ_ZEROC;
372 	if (err != 0 || req->newptr == NULL || temp == sc->temp_throttle_val)
373 		return (err);
374 
375 	/* Value changed, update counts in softc and hardware. */
376 	sc->temp_throttle_val = temp;
377 	sc->temp_throttle_trigger_cnt = temp_to_count(sc, sc->temp_throttle_val);
378 	sc->temp_throttle_reset_cnt = temp_to_count(sc, sc->temp_throttle_val - 100);
379 	imx6_anatop_write_4(IMX6_ANALOG_TEMPMON_TEMPSENSE0_CLR,
380 	    IMX6_ANALOG_TEMPMON_TEMPSENSE0_ALARM_MASK);
381 	imx6_anatop_write_4(IMX6_ANALOG_TEMPMON_TEMPSENSE0_SET,
382 	    (sc->temp_throttle_trigger_cnt <<
383 	     IMX6_ANALOG_TEMPMON_TEMPSENSE0_ALARM_SHIFT));
384 	return (err);
385 }
386 
387 static void
388 tempmon_gofast(struct imx6_anatop_softc *sc)
389 {
390 
391 	if (sc->cpu_curhz < sc->cpu_maxhz) {
392 		vdd_set(sc, sc->cpu_maxmv);
393 		cpufreq_set_clock(sc, sc->cpu_maxhz);
394 	}
395 }
396 
397 static void
398 tempmon_goslow(struct imx6_anatop_softc *sc)
399 {
400 
401 	if (sc->cpu_curhz > sc->cpu_minhz) {
402 		cpufreq_set_clock(sc, sc->cpu_minhz);
403 		vdd_set(sc, sc->cpu_minmv);
404 	}
405 }
406 
407 static int
408 tempmon_intr(void *arg)
409 {
410 	struct imx6_anatop_softc *sc = arg;
411 
412 	/*
413 	 * XXX Note that this code doesn't currently run (for some mysterious
414 	 * reason we just never get an interrupt), so the real monitoring is
415 	 * done by tempmon_throttle_check().
416 	 */
417 	tempmon_goslow(sc);
418 	/* XXX Schedule callout to speed back up eventually. */
419 	return (FILTER_HANDLED);
420 }
421 
422 static void
423 tempmon_throttle_check(void *arg)
424 {
425 	struct imx6_anatop_softc *sc = arg;
426 
427 	/* Lower counts are higher temperatures. */
428 	if (sc->temp_last_cnt < sc->temp_throttle_trigger_cnt)
429 		tempmon_goslow(sc);
430 	else if (sc->temp_last_cnt > (sc->temp_throttle_reset_cnt))
431 		tempmon_gofast(sc);
432 
433 	callout_reset_sbt(&sc->temp_throttle_callout, sc->temp_throttle_delay,
434 		0, tempmon_throttle_check, sc, 0);
435 
436 }
437 
438 static void
439 initialize_tempmon(struct imx6_anatop_softc *sc)
440 {
441 	uint32_t cal;
442 	struct sysctl_ctx_list *ctx;
443 
444 	/*
445 	 * Fetch calibration data: a sensor count at room temperature (25C),
446 	 * a sensor count at a high temperature, and that temperature
447 	 */
448 	cal = fsl_ocotp_read_4(FSL_OCOTP_ANA1);
449 	sc->temp_room_cnt = (cal & 0xFFF00000) >> 20;
450 	sc->temp_high_cnt = (cal & 0x000FFF00) >> 8;
451 	sc->temp_high_val = (cal & 0x000000FF) * 10;
452 
453 	/*
454 	 * Throttle to a lower cpu freq at 10C below the "hot" temperature, and
455 	 * reset back to max cpu freq at 5C below the trigger.
456 	 */
457 	sc->temp_throttle_val = sc->temp_high_val - 100;
458 	sc->temp_throttle_trigger_cnt =
459 	    temp_to_count(sc, sc->temp_throttle_val);
460 	sc->temp_throttle_reset_cnt =
461 	    temp_to_count(sc, sc->temp_throttle_val - 50);
462 
463 	/*
464 	 * Set the sensor to sample automatically at 16Hz (32.768KHz/0x800), set
465 	 * the throttle count, and begin making measurements.
466 	 */
467 	imx6_anatop_write_4(IMX6_ANALOG_TEMPMON_TEMPSENSE1, 0x0800);
468 	imx6_anatop_write_4(IMX6_ANALOG_TEMPMON_TEMPSENSE0,
469 	    (sc->temp_throttle_trigger_cnt <<
470 	    IMX6_ANALOG_TEMPMON_TEMPSENSE0_ALARM_SHIFT) |
471 	    IMX6_ANALOG_TEMPMON_TEMPSENSE0_MEASURE);
472 
473 	/*
474 	 * XXX Note that the alarm-interrupt feature isn't working yet, so
475 	 * we'll use a callout handler to check at 10Hz.  Make sure we have an
476 	 * initial temperature reading before starting up the callouts so we
477 	 * don't get a bogus reading of zero.
478 	 */
479 	while (sc->temp_last_cnt == 0)
480 		temp_update_count(sc);
481 	sc->temp_throttle_delay = 100 * SBT_1MS;
482 	callout_init(&sc->temp_throttle_callout, 0);
483 	callout_reset_sbt(&sc->temp_throttle_callout, sc->temp_throttle_delay,
484 	    0, tempmon_throttle_check, sc, 0);
485 
486 	ctx = device_get_sysctl_ctx(sc->dev);
487 	SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(device_get_sysctl_tree(sc->dev)),
488 	    OID_AUTO, "temperature", CTLTYPE_INT | CTLFLAG_RD, sc, 0,
489 	    temp_sysctl_handler, "IK", "Current die temperature");
490 	SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(device_get_sysctl_tree(sc->dev)),
491 	    OID_AUTO, "throttle_temperature", CTLTYPE_INT | CTLFLAG_RW, sc,
492 	    0, temp_throttle_sysctl_handler, "IK",
493 	    "Throttle CPU when exceeding this temperature");
494 }
495 
496 static int
497 imx6_anatop_detach(device_t dev)
498 {
499 
500 	return (EBUSY);
501 }
502 
503 static int
504 imx6_anatop_attach(device_t dev)
505 {
506 	struct imx6_anatop_softc *sc;
507 	int err;
508 
509 	sc = device_get_softc(dev);
510 	sc->dev = dev;
511 
512 	/* Allocate bus_space resources. */
513 	if (bus_alloc_resources(dev, imx6_anatop_spec, sc->res)) {
514 		device_printf(dev, "Cannot allocate resources\n");
515 		err = ENXIO;
516 		goto out;
517 	}
518 
519 	err = bus_setup_intr(dev, sc->res[IRQRES], INTR_TYPE_MISC | INTR_MPSAFE,
520 	    tempmon_intr, NULL, sc, &sc->temp_intrhand);
521 	if (err != 0)
522 		goto out;
523 
524 	SYSCTL_ADD_UINT(device_get_sysctl_ctx(sc->dev),
525 	    SYSCTL_CHILDREN(device_get_sysctl_tree(sc->dev)),
526 	    OID_AUTO, "cpu_voltage", CTLFLAG_RD,
527 	    &sc->cpu_curmv, 0, "Current CPU voltage in millivolts");
528 
529 	imx6_anatop_sc = sc;
530 
531 	/*
532 	 * Other code seen on the net sets this SELFBIASOFF flag around the same
533 	 * time the temperature sensor is set up, although it's unclear how the
534 	 * two are related (if at all).
535 	 */
536 	imx6_anatop_write_4(IMX6_ANALOG_PMU_MISC0_SET,
537 	    IMX6_ANALOG_PMU_MISC0_SELFBIASOFF);
538 
539 	cpufreq_initialize(sc);
540 	initialize_tempmon(sc);
541 
542 	err = 0;
543 
544 out:
545 
546 	if (err != 0) {
547 		bus_release_resources(dev, imx6_anatop_spec, sc->res);
548 	}
549 
550 	return (err);
551 }
552 
553 static int
554 imx6_anatop_probe(device_t dev)
555 {
556 
557 	if (!ofw_bus_status_okay(dev))
558 		return (ENXIO);
559 
560 	if (ofw_bus_is_compatible(dev, "fsl,imx6q-anatop") == 0)
561 		return (ENXIO);
562 
563 	device_set_desc(dev, "Freescale i.MX6 Analog PLLs and Power");
564 
565 	return (BUS_PROBE_DEFAULT);
566 }
567 
568 uint32_t
569 imx6_get_cpu_clock()
570 {
571 	uint32_t div;
572 
573 	div = imx6_anatop_read_4(IMX6_ANALOG_CCM_PLL_ARM) &
574 	    IMX6_ANALOG_CCM_PLL_ARM_DIV_MASK;
575 	return (cpufreq_hz_from_div(imx6_anatop_sc, div));
576 }
577 
578 static device_method_t imx6_anatop_methods[] = {
579 	/* Device interface */
580 	DEVMETHOD(device_probe,  imx6_anatop_probe),
581 	DEVMETHOD(device_attach, imx6_anatop_attach),
582 	DEVMETHOD(device_detach, imx6_anatop_detach),
583 
584 	DEVMETHOD_END
585 };
586 
587 static driver_t imx6_anatop_driver = {
588 	"imx6_anatop",
589 	imx6_anatop_methods,
590 	sizeof(struct imx6_anatop_softc)
591 };
592 
593 static devclass_t imx6_anatop_devclass;
594 
595 DRIVER_MODULE(imx6_anatop, simplebus, imx6_anatop_driver, imx6_anatop_devclass, 0, 0);
596 
597