summaryrefslogtreecommitdiffstats
path: root/arch/arm/mach-omap2/vc.c
blob: 49ac7977e03e5457e3c4855fb60bc3c3f76cdc9c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
/*
 * OMAP Voltage Controller (VC) interface
 *
 * Copyright (C) 2011 Texas Instruments, Inc.
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/bug.h>
#include <linux/io.h>

#include <asm/div64.h>

#include "iomap.h"
#include "soc.h"
#include "voltage.h"
#include "vc.h"
#include "prm-regbits-34xx.h"
#include "prm-regbits-44xx.h"
#include "prm44xx.h"
#include "pm.h"
#include "scrm44xx.h"
#include "control.h"

/**
 * struct omap_vc_channel_cfg - describe the cfg_channel bitfield
 * @sa: bit for slave address
 * @rav: bit for voltage configuration register
 * @rac: bit for command configuration register
 * @racen: enable bit for RAC
 * @cmd: bit for command value set selection
 *
 * Channel configuration bits, common for OMAP3+
 * OMAP3 register: PRM_VC_CH_CONF
 * OMAP4 register: PRM_VC_CFG_CHANNEL
 * OMAP5 register: PRM_VC_SMPS_<voltdm>_CONFIG
 */
struct omap_vc_channel_cfg {
	u8 sa;
	u8 rav;
	u8 rac;
	u8 racen;
	u8 cmd;
};

static struct omap_vc_channel_cfg vc_default_channel_cfg = {
	.sa    = BIT(0),
	.rav   = BIT(1),
	.rac   = BIT(2),
	.racen = BIT(3),
	.cmd   = BIT(4),
};

/*
 * On OMAP3+, all VC channels have the above default bitfield
 * configuration, except the OMAP4 MPU channel.  This appears
 * to be a freak accident as every other VC channel has the
 * default configuration, thus creating a mutant channel config.
 */
static struct omap_vc_channel_cfg vc_mutant_channel_cfg = {
	.sa    = BIT(0),
	.rav   = BIT(2),
	.rac   = BIT(3),
	.racen = BIT(4),
	.cmd   = BIT(1),
};

static struct omap_vc_channel_cfg *vc_cfg_bits;

/* Default I2C trace length on pcb, 6.3cm. Used for capacitance calculations. */
static u32 sr_i2c_pcb_length = 63;
#define CFG_CHANNEL_MASK 0x1f

/**
 * omap_vc_config_channel - configure VC channel to PMIC mappings
 * @voltdm: pointer to voltagdomain defining the desired VC channel
 *
 * Configures the VC channel to PMIC mappings for the following
 * PMIC settings
 * - i2c slave address (SA)
 * - voltage configuration address (RAV)
 * - command configuration address (RAC) and enable bit (RACEN)
 * - command values for ON, ONLP, RET and OFF (CMD)
 *
 * This function currently only allows flexible configuration of the
 * non-default channel.  Starting with OMAP4, there are more than 2
 * channels, with one defined as the default (on OMAP4, it's MPU.)
 * Only the non-default channel can be configured.
 */
static int omap_vc_config_channel(struct voltagedomain *voltdm)
{
	struct omap_vc_channel *vc = voltdm->vc;

	/*
	 * For default channel, the only configurable bit is RACEN.
	 * All others must stay at zero (see function comment above.)
	 */
	if (vc->flags & OMAP_VC_CHANNEL_DEFAULT)
		vc->cfg_channel &= vc_cfg_bits->racen;

	voltdm->rmw(CFG_CHANNEL_MASK << vc->cfg_channel_sa_shift,
		    vc->cfg_channel << vc->cfg_channel_sa_shift,
		    vc->cfg_channel_reg);

	return 0;
}

/* Voltage scale and accessory APIs */
int omap_vc_pre_scale(struct voltagedomain *voltdm,
		      unsigned long target_volt,
		      u8 *target_vsel, u8 *current_vsel)
{
	struct omap_vc_channel *vc = voltdm->vc;
	u32 vc_cmdval;

	/* Check if sufficient pmic info is available for this vdd */
	if (!voltdm->pmic) {
		pr_err("%s: Insufficient pmic info to scale the vdd_%s\n",
			__func__, voltdm->name);
		return -EINVAL;
	}

	if (!voltdm->pmic->uv_to_vsel) {
		pr_err("%s: PMIC function to convert voltage in uV to vsel not registered. Hence unable to scale voltage for vdd_%s\n",
		       __func__, voltdm->name);
		return -ENODATA;
	}

	if (!voltdm->read || !voltdm->write) {
		pr_err("%s: No read/write API for accessing vdd_%s regs\n",
			__func__, voltdm->name);
		return -EINVAL;
	}

	*target_vsel = voltdm->pmic->uv_to_vsel(target_volt);
	*current_vsel = voltdm->pmic->uv_to_vsel(voltdm->nominal_volt);

	/* Setting the ON voltage to the new target voltage */
	vc_cmdval = voltdm->read(vc->cmdval_reg);
	vc_cmdval &= ~vc->common->cmd_on_mask;
	vc_cmdval |= (*target_vsel << vc->common->cmd_on_shift);
	voltdm->write(vc_cmdval, vc->cmdval_reg);

	voltdm->vc_param->on = target_volt;

	omap_vp_update_errorgain(voltdm, target_volt);

	return 0;
}

void omap_vc_post_scale(struct voltagedomain *voltdm,
			unsigned long target_volt,
			u8 target_vsel, u8 current_vsel)
{
	u32 smps_steps = 0, smps_delay = 0;

	smps_steps = abs(target_vsel - current_vsel);
	/* SMPS slew rate / step size. 2us added as buffer. */
	smps_delay = ((smps_steps * voltdm->pmic->step_size) /
			voltdm->pmic->slew_rate) + 2;
	udelay(smps_delay);
}

/* vc_bypass_scale - VC bypass method of voltage scaling */
int omap_vc_bypass_scale(struct voltagedomain *voltdm,
			 unsigned long target_volt)
{
	struct omap_vc_channel *vc = voltdm->vc;
	u32 loop_cnt = 0, retries_cnt = 0;
	u32 vc_valid, vc_bypass_val_reg, vc_bypass_value;
	u8 target_vsel, current_vsel;
	int ret;

	ret = omap_vc_pre_scale(voltdm, target_volt, &target_vsel, &current_vsel);
	if (ret)
		return ret;

	vc_valid = vc->common->valid;
	vc_bypass_val_reg = vc->common->bypass_val_reg;
	vc_bypass_value = (target_vsel << vc->common->data_shift) |
		(vc->volt_reg_addr << vc->common->regaddr_shift) |
		(vc->i2c_slave_addr << vc->common->slaveaddr_shift);

	voltdm->write(vc_bypass_value, vc_bypass_val_reg);
	voltdm->write(vc_bypass_value | vc_valid, vc_bypass_val_reg);

	vc_bypass_value = voltdm->read(vc_bypass_val_reg);
	/*
	 * Loop till the bypass command is acknowledged from the SMPS.
	 * NOTE: This is legacy code. The loop count and retry count needs
	 * to be revisited.
	 */
	while (!(vc_bypass_value & vc_valid)) {
		loop_cnt++;

		if (retries_cnt > 10) {
			pr_warning("%s: Retry count exceeded\n", __func__);
			return -ETIMEDOUT;
		}

		if (loop_cnt > 50) {
			retries_cnt++;
			loop_cnt = 0;
			udelay(10);
		}
		vc_bypass_value = voltdm->read(vc_bypass_val_reg);
	}

	omap_vc_post_scale(voltdm, target_volt, target_vsel, current_vsel);
	return 0;
}

/* Convert microsecond value to number of 32kHz clock cycles */
static inline u32 omap_usec_to_32k(u32 usec)
{
	return DIV_ROUND_UP_ULL(32768ULL * (u64)usec, 1000000ULL);
}

/* Set oscillator setup time for omap3 */
static void omap3_set_clksetup(u32 usec, struct voltagedomain *voltdm)
{
	voltdm->write(omap_usec_to_32k(usec), OMAP3_PRM_CLKSETUP_OFFSET);
}

/**
 * omap3_set_i2c_timings - sets i2c sleep timings for a channel
 * @voltdm: channel to configure
 * @off_mode: select whether retention or off mode values used
 *
 * Calculates and sets up voltage controller to use I2C based
 * voltage scaling for sleep modes. This can be used for either off mode
 * or retention. Off mode has additionally an option to use sys_off_mode
 * pad, which uses a global signal to program the whole power IC to
 * off-mode.
 */
static void omap3_set_i2c_timings(struct voltagedomain *voltdm, bool off_mode)
{
	unsigned long voltsetup1;
	u32 tgt_volt;

	/*
	 * Oscillator is shut down only if we are using sys_off_mode pad,
	 * thus we set a minimal setup time here
	 */
	omap3_set_clksetup(1, voltdm);

	if (off_mode)
		tgt_volt = voltdm->vc_param->off;
	else
		tgt_volt = voltdm->vc_param->ret;

	voltsetup1 = (voltdm->vc_param->on - tgt_volt) /
			voltdm->pmic->slew_rate;

	voltsetup1 = voltsetup1 * voltdm->sys_clk.rate / 8 / 1000000 + 1;

	voltdm->rmw(voltdm->vfsm->voltsetup_mask,
		voltsetup1 << __ffs(voltdm->vfsm->voltsetup_mask),
		voltdm->vfsm->voltsetup_reg);

	/*
	 * pmic is not controlling the voltage scaling during retention,
	 * thus set voltsetup2 to 0
	 */
	voltdm->write(0, OMAP3_PRM_VOLTSETUP2_OFFSET);
}

/**
 * omap3_set_off_timings - sets off-mode timings for a channel
 * @voltdm: channel to configure
 *
 * Calculates and sets up off-mode timings for a channel. Off-mode
 * can use either I2C based voltage scaling, or alternatively
 * sys_off_mode pad can be used to send a global command to power IC.
 * This function first checks which mode is being used, and calls
 * omap3_set_i2c_timings() if the system is using I2C control mode.
 * sys_off_mode has the additional benefit that voltages can be
 * scaled to zero volt level with TWL4030 / TWL5030, I2C can only
 * scale to 600mV.
 */
static void omap3_set_off_timings(struct voltagedomain *voltdm)
{
	unsigned long clksetup;
	unsigned long voltsetup2;
	unsigned long voltsetup2_old;
	u32 val;
	u32 tstart, tshut;

	/* check if sys_off_mode is used to control off-mode voltages */
	val = voltdm->read(OMAP3_PRM_VOLTCTRL_OFFSET);
	if (!(val & OMAP3430_SEL_OFF_MASK)) {
		/* No, omap is controlling them over I2C */
		omap3_set_i2c_timings(voltdm, true);
		return;
	}

	omap_pm_get_oscillator(&tstart, &tshut);
	omap3_set_clksetup(tstart, voltdm);

	clksetup = voltdm->read(OMAP3_PRM_CLKSETUP_OFFSET);

	/* voltsetup 2 in us */
	voltsetup2 = voltdm->vc_param->on / voltdm->pmic->slew_rate;

	/* convert to 32k clk cycles */
	voltsetup2 = DIV_ROUND_UP(voltsetup2 * 32768, 1000000);

	voltsetup2_old = voltdm->read(OMAP3_PRM_VOLTSETUP2_OFFSET);

	/*
	 * Update voltsetup2 if higher than current value (needed because
	 * we have multiple channels with different ramp times), also
	 * update voltoffset always to value recommended by TRM
	 */
	if (voltsetup2 > voltsetup2_old) {
		voltdm->write(voltsetup2, OMAP3_PRM_VOLTSETUP2_OFFSET);
		voltdm->write(clksetup - voltsetup2,
			OMAP3_PRM_VOLTOFFSET_OFFSET);
	} else
		voltdm->write(clksetup - voltsetup2_old,
			OMAP3_PRM_VOLTOFFSET_OFFSET);

	/*
	 * omap is not controlling voltage scaling during off-mode,
	 * thus set voltsetup1 to 0
	 */
	voltdm->rmw(voltdm->vfsm->voltsetup_mask, 0,
		voltdm->vfsm->voltsetup_reg);

	/* voltoffset must be clksetup minus voltsetup2 according to TRM */
	voltdm->write(clksetup - voltsetup2, OMAP3_PRM_VOLTOFFSET_OFFSET);
}

static void __init omap3_vc_init_channel(struct voltagedomain *voltdm)
{
	omap3_set_off_timings(voltdm);
}

/**
 * omap4_calc_volt_ramp - calculates voltage ramping delays on omap4
 * @voltdm: channel to calculate values for
 * @voltage_diff: voltage difference in microvolts
 *
 * Calculates voltage ramp prescaler + counter values for a voltage
 * difference on omap4. Returns a field value suitable for writing to
 * VOLTSETUP register for a channel in following format:
 * bits[8:9] prescaler ... bits[0:5] counter. See OMAP4 TRM for reference.
 */
static u32 omap4_calc_volt_ramp(struct voltagedomain *voltdm, u32 voltage_diff)
{
	u32 prescaler;
	u32 cycles;
	u32 time;

	time = voltage_diff / voltdm->pmic->slew_rate;

	cycles = voltdm->sys_clk.rate / 1000 * time / 1000;

	cycles /= 64;
	prescaler = 0;

	/* shift to next prescaler until no overflow */

	/* scale for div 256 = 64 * 4 */
	if (cycles > 63) {
		cycles /= 4;
		prescaler++;
	}

	/* scale for div 512 = 256 * 2 */
	if (cycles > 63) {
		cycles /= 2;
		prescaler++;
	}

	/* scale for div 2048 = 512 * 4 */
	if (cycles > 63) {
		cycles /= 4;
		prescaler++;
	}

	/* check for overflow => invalid ramp time */
	if (cycles > 63) {
		pr_warn("%s: invalid setuptime for vdd_%s\n", __func__,
			voltdm->name);
		return 0;
	}

	cycles++;

	return (prescaler << OMAP4430_RAMP_UP_PRESCAL_SHIFT) |
		(cycles << OMAP4430_RAMP_UP_COUNT_SHIFT);
}

/**
 * omap4_usec_to_val_scrm - convert microsecond value to SCRM module bitfield
 * @usec: microseconds
 * @shift: number of bits to shift left
 * @mask: bitfield mask
 *
 * Converts microsecond value to OMAP4 SCRM bitfield. Bitfield is
 * shifted to requested position, and checked agains the mask value.
 * If larger, forced to the max value of the field (i.e. the mask itself.)
 * Returns the SCRM bitfield value.
 */
static u32 omap4_usec_to_val_scrm(u32 usec, int shift, u32 mask)
{
	u32 val;

	val = omap_usec_to_32k(usec) << shift;

	/* Check for overflow, if yes, force to max value */
	if (val > mask)
		val = mask;

	return val;
}

/**
 * omap4_set_timings - set voltage ramp timings for a channel
 * @voltdm: channel to configure
 * @off_mode: whether off-mode values are used
 *
 * Calculates and sets the voltage ramp up / down values for a channel.
 */
static void omap4_set_timings(struct voltagedomain *voltdm, bool off_mode)
{
	u32 val;
	u32 ramp;
	int offset;
	u32 tstart, tshut;

	if (off_mode) {
		ramp = omap4_calc_volt_ramp(voltdm,
			voltdm->vc_param->on - voltdm->vc_param->off);
		offset = voltdm->vfsm->voltsetup_off_reg;
	} else {
		ramp = omap4_calc_volt_ramp(voltdm,
			voltdm->vc_param->on - voltdm->vc_param->ret);
		offset = voltdm->vfsm->voltsetup_reg;
	}

	if (!ramp)
		return;

	val = voltdm->read(offset);

	val |= ramp << OMAP4430_RAMP_DOWN_COUNT_SHIFT;

	val |= ramp << OMAP4430_RAMP_UP_COUNT_SHIFT;

	voltdm->write(val, offset);

	omap_pm_get_oscillator(&tstart, &tshut);

	val = omap4_usec_to_val_scrm(tstart, OMAP4_SETUPTIME_SHIFT,
		OMAP4_SETUPTIME_MASK);
	val |= omap4_usec_to_val_scrm(tshut, OMAP4_DOWNTIME_SHIFT,
		OMAP4_DOWNTIME_MASK);

	__raw_writel(val, OMAP4_SCRM_CLKSETUPTIME);
}

/* OMAP4 specific voltage init functions */
static void __init omap4_vc_init_channel(struct voltagedomain *voltdm)
{
	omap4_set_timings(voltdm, true);
	omap4_set_timings(voltdm, false);
}

struct i2c_init_data {
	u8 loadbits;
	u8 load;
	u8 hsscll_38_4;
	u8 hsscll_26;
	u8 hsscll_19_2;
	u8 hsscll_16_8;
	u8 hsscll_12;
};

static const __initdata struct i2c_init_data omap4_i2c_timing_data[] = {
	{
		.load = 50,
		.loadbits = 0x3,
		.hsscll_38_4 = 13,
		.hsscll_26 = 11,
		.hsscll_19_2 = 9,
		.hsscll_16_8 = 9,
		.hsscll_12 = 8,
	},
	{
		.load = 25,
		.loadbits = 0x2,
		.hsscll_38_4 = 13,
		.hsscll_26 = 11,
		.hsscll_19_2 = 9,
		.hsscll_16_8 = 9,
		.hsscll_12 = 8,
	},
	{
		.load = 12,
		.loadbits = 0x1,
		.hsscll_38_4 = 11,
		.hsscll_26 = 10,
		.hsscll_19_2 = 9,
		.hsscll_16_8 = 9,
		.hsscll_12 = 8,
	},
	{
		.load = 0,
		.loadbits = 0x0,
		.hsscll_38_4 = 12,
		.hsscll_26 = 10,
		.hsscll_19_2 = 9,
		.hsscll_16_8 = 8,
		.hsscll_12 = 8,
	},
};

/**
 * omap4_vc_i2c_timing_init - sets up board I2C timing parameters
 * @voltdm: voltagedomain pointer to get data from
 *
 * Use PMIC + board supplied settings for calculating the total I2C
 * channel capacitance and set the timing parameters based on this.
 * Pre-calculated values are provided in data tables, as it is not
 * too straightforward to calculate these runtime.
 */
static void __init omap4_vc_i2c_timing_init(struct voltagedomain *voltdm)
{
	u32 capacitance;
	u32 val;
	u16 hsscll;
	const struct i2c_init_data *i2c_data;

	if (!voltdm->pmic->i2c_high_speed) {
		pr_warn("%s: only high speed supported!\n", __func__);
		return;
	}

	/* PCB trace capacitance, 0.125pF / mm => mm / 8 */
	capacitance = DIV_ROUND_UP(sr_i2c_pcb_length, 8);

	/* OMAP pad capacitance */
	capacitance += 4;

	/* PMIC pad capacitance */
	capacitance += voltdm->pmic->i2c_pad_load;

	/* Search for capacitance match in the table */
	i2c_data = omap4_i2c_timing_data;

	while (i2c_data->load > capacitance)
		i2c_data++;

	/* Select proper values based on sysclk frequency */
	switch (voltdm->sys_clk.rate) {
	case 38400000:
		hsscll = i2c_data->hsscll_38_4;
		break;
	case 26000000:
		hsscll = i2c_data->hsscll_26;
		break;
	case 19200000:
		hsscll = i2c_data->hsscll_19_2;
		break;
	case 16800000:
		hsscll = i2c_data->hsscll_16_8;
		break;
	case 12000000:
		hsscll = i2c_data->hsscll_12;
		break;
	default:
		pr_warn("%s: unsupported sysclk rate: %d!\n", __func__,
			voltdm->sys_clk.rate);
		return;
	}

	/* Loadbits define pull setup for the I2C channels */
	val = i2c_data->loadbits << 25 | i2c_data->loadbits << 29;

	/* Write to SYSCTRL_PADCONF_WKUP_CTRL_I2C_2 to setup I2C pull */
	__raw_writel(val, OMAP2_L4_IO_ADDRESS(OMAP4_CTRL_MODULE_PAD_WKUP +
				OMAP4_CTRL_MODULE_PAD_WKUP_CONTROL_I2C_2));

	/* HSSCLH can always be zero */
	val = hsscll << OMAP4430_HSSCLL_SHIFT;
	val |= (0x28 << OMAP4430_SCLL_SHIFT | 0x2c << OMAP4430_SCLH_SHIFT);

	/* Write setup times to I2C config register */
	voltdm->write(val, OMAP4_PRM_VC_CFG_I2C_CLK_OFFSET);
}



/**
 * omap_vc_i2c_init - initialize I2C interface to PMIC
 * @voltdm: voltage domain containing VC data
 *
 * Use PMIC supplied settings for I2C high-speed mode and
 * master code (if set) and program the VC I2C configuration
 * register.
 *
 * The VC I2C configuration is common to all VC channels,
 * so this function only configures I2C for the first VC
 * channel registers.  All other VC channels will use the
 * same configuration.
 */
static void __init omap_vc_i2c_init(struct voltagedomain *voltdm)
{
	struct omap_vc_channel *vc = voltdm->vc;
	static bool initialized;
	static bool i2c_high_speed;
	u8 mcode;

	if (initialized) {
		if (voltdm->pmic->i2c_high_speed != i2c_high_speed)
			pr_warn("%s: I2C config for vdd_%s does not match other channels (%u).\n",
				__func__, voltdm->name, i2c_high_speed);
		return;
	}

	i2c_high_speed = voltdm->pmic->i2c_high_speed;
	if (i2c_high_speed)
		voltdm->rmw(vc->common->i2c_cfg_hsen_mask,
			    vc->common->i2c_cfg_hsen_mask,
			    vc->common->i2c_cfg_reg);

	mcode = voltdm->pmic->i2c_mcode;
	if (mcode)
		voltdm->rmw(vc->common->i2c_mcode_mask,
			    mcode << __ffs(vc->common->i2c_mcode_mask),
			    vc->common->i2c_cfg_reg);

	if (cpu_is_omap44xx())
		omap4_vc_i2c_timing_init(voltdm);

	initialized = true;
}

/**
 * omap_vc_calc_vsel - calculate vsel value for a channel
 * @voltdm: channel to calculate value for
 * @uvolt: microvolt value to convert to vsel
 *
 * Converts a microvolt value to vsel value for the used PMIC.
 * This checks whether the microvolt value is out of bounds, and
 * adjusts the value accordingly. If unsupported value detected,
 * warning is thrown.
 */
static u8 omap_vc_calc_vsel(struct voltagedomain *voltdm, u32 uvolt)
{
	if (voltdm->pmic->vddmin > uvolt)
		uvolt = voltdm->pmic->vddmin;
	if (voltdm->pmic->vddmax < uvolt) {
		WARN(1, "%s: voltage not supported by pmic: %u vs max %u\n",
			__func__, uvolt, voltdm->pmic->vddmax);
		/* Lets try maximum value anyway */
		uvolt = voltdm->pmic->vddmax;
	}

	return voltdm->pmic->uv_to_vsel(uvolt);
}

#ifdef CONFIG_PM
/**
 * omap_pm_setup_sr_i2c_pcb_length - set length of SR I2C traces on PCB
 * @mm: length of the PCB trace in millimetres
 *
 * Sets the PCB trace length for the I2C channel. By default uses 63mm.
 * This is needed for properly calculating the capacitance value for
 * the PCB trace, and for setting the SR I2C channel timing parameters.
 */
void __init omap_pm_setup_sr_i2c_pcb_length(u32 mm)
{
	sr_i2c_pcb_length = mm;
}
#endif

void __init omap_vc_init_channel(struct voltagedomain *voltdm)
{
	struct omap_vc_channel *vc = voltdm->vc;
	u8 on_vsel, onlp_vsel, ret_vsel, off_vsel;
	u32 val;

	if (!voltdm->pmic || !voltdm->pmic->uv_to_vsel) {
		pr_err("%s: No PMIC info for vdd_%s\n", __func__, voltdm->name);
		return;
	}

	if (!voltdm->read || !voltdm->write) {
		pr_err("%s: No read/write API for accessing vdd_%s regs\n",
			__func__, voltdm->name);
		return;
	}

	vc->cfg_channel = 0;
	if (vc->flags & OMAP_VC_CHANNEL_CFG_MUTANT)
		vc_cfg_bits = &vc_mutant_channel_cfg;
	else
		vc_cfg_bits = &vc_default_channel_cfg;

	/* get PMIC/board specific settings */
	vc->i2c_slave_addr = voltdm->pmic->i2c_slave_addr;
	vc->volt_reg_addr = voltdm->pmic->volt_reg_addr;
	vc->cmd_reg_addr = voltdm->pmic->cmd_reg_addr;

	/* Configure the i2c slave address for this VC */
	voltdm->rmw(vc->smps_sa_mask,
		    vc->i2c_slave_addr << __ffs(vc->smps_sa_mask),
		    vc->smps_sa_reg);
	vc->cfg_channel |= vc_cfg_bits->sa;

	/*
	 * Configure the PMIC register addresses.
	 */
	voltdm->rmw(vc->smps_volra_mask,
		    vc->volt_reg_addr << __ffs(vc->smps_volra_mask),
		    vc->smps_volra_reg);
	vc->cfg_channel |= vc_cfg_bits->rav;

	if (vc->cmd_reg_addr) {
		voltdm->rmw(vc->smps_cmdra_mask,
			    vc->cmd_reg_addr << __ffs(vc->smps_cmdra_mask),
			    vc->smps_cmdra_reg);
		vc->cfg_channel |= vc_cfg_bits->rac;
	}

	if (vc->cmd_reg_addr == vc->volt_reg_addr)
		vc->cfg_channel |= vc_cfg_bits->racen;

	/* Set up the on, inactive, retention and off voltage */
	on_vsel = omap_vc_calc_vsel(voltdm, voltdm->vc_param->on);
	onlp_vsel = omap_vc_calc_vsel(voltdm, voltdm->vc_param->onlp);
	ret_vsel = omap_vc_calc_vsel(voltdm, voltdm->vc_param->ret);
	off_vsel = omap_vc_calc_vsel(voltdm, voltdm->vc_param->off);

	val = ((on_vsel << vc->common->cmd_on_shift) |
	       (onlp_vsel << vc->common->cmd_onlp_shift) |
	       (ret_vsel << vc->common->cmd_ret_shift) |
	       (off_vsel << vc->common->cmd_off_shift));
	voltdm->write(val, vc->cmdval_reg);
	vc->cfg_channel |= vc_cfg_bits->cmd;

	/* Channel configuration */
	omap_vc_config_channel(voltdm);

	omap_vc_i2c_init(voltdm);

	if (cpu_is_omap34xx())
		omap3_vc_init_channel(voltdm);
	else if (cpu_is_omap44xx())
		omap4_vc_init_channel(voltdm);
}