xref: /openbmc/linux/arch/arm/mach-omap2/vc.c (revision b34e08d5)
1 /*
2  * OMAP Voltage Controller (VC) interface
3  *
4  * Copyright (C) 2011 Texas Instruments, Inc.
5  *
6  * This file is licensed under the terms of the GNU General Public
7  * License version 2. This program is licensed "as is" without any
8  * warranty of any kind, whether express or implied.
9  */
10 #include <linux/kernel.h>
11 #include <linux/delay.h>
12 #include <linux/init.h>
13 #include <linux/bug.h>
14 #include <linux/io.h>
15 
16 #include <asm/div64.h>
17 
18 #include "iomap.h"
19 #include "soc.h"
20 #include "voltage.h"
21 #include "vc.h"
22 #include "prm-regbits-34xx.h"
23 #include "prm-regbits-44xx.h"
24 #include "prm44xx.h"
25 #include "pm.h"
26 #include "scrm44xx.h"
27 #include "control.h"
28 
29 /**
30  * struct omap_vc_channel_cfg - describe the cfg_channel bitfield
31  * @sa: bit for slave address
32  * @rav: bit for voltage configuration register
33  * @rac: bit for command configuration register
34  * @racen: enable bit for RAC
35  * @cmd: bit for command value set selection
36  *
37  * Channel configuration bits, common for OMAP3+
38  * OMAP3 register: PRM_VC_CH_CONF
39  * OMAP4 register: PRM_VC_CFG_CHANNEL
40  * OMAP5 register: PRM_VC_SMPS_<voltdm>_CONFIG
41  */
42 struct omap_vc_channel_cfg {
43 	u8 sa;
44 	u8 rav;
45 	u8 rac;
46 	u8 racen;
47 	u8 cmd;
48 };
49 
50 static struct omap_vc_channel_cfg vc_default_channel_cfg = {
51 	.sa    = BIT(0),
52 	.rav   = BIT(1),
53 	.rac   = BIT(2),
54 	.racen = BIT(3),
55 	.cmd   = BIT(4),
56 };
57 
58 /*
59  * On OMAP3+, all VC channels have the above default bitfield
60  * configuration, except the OMAP4 MPU channel.  This appears
61  * to be a freak accident as every other VC channel has the
62  * default configuration, thus creating a mutant channel config.
63  */
64 static struct omap_vc_channel_cfg vc_mutant_channel_cfg = {
65 	.sa    = BIT(0),
66 	.rav   = BIT(2),
67 	.rac   = BIT(3),
68 	.racen = BIT(4),
69 	.cmd   = BIT(1),
70 };
71 
72 static struct omap_vc_channel_cfg *vc_cfg_bits;
73 
74 /* Default I2C trace length on pcb, 6.3cm. Used for capacitance calculations. */
75 static u32 sr_i2c_pcb_length = 63;
76 #define CFG_CHANNEL_MASK 0x1f
77 
78 /**
79  * omap_vc_config_channel - configure VC channel to PMIC mappings
80  * @voltdm: pointer to voltagdomain defining the desired VC channel
81  *
82  * Configures the VC channel to PMIC mappings for the following
83  * PMIC settings
84  * - i2c slave address (SA)
85  * - voltage configuration address (RAV)
86  * - command configuration address (RAC) and enable bit (RACEN)
87  * - command values for ON, ONLP, RET and OFF (CMD)
88  *
89  * This function currently only allows flexible configuration of the
90  * non-default channel.  Starting with OMAP4, there are more than 2
91  * channels, with one defined as the default (on OMAP4, it's MPU.)
92  * Only the non-default channel can be configured.
93  */
94 static int omap_vc_config_channel(struct voltagedomain *voltdm)
95 {
96 	struct omap_vc_channel *vc = voltdm->vc;
97 
98 	/*
99 	 * For default channel, the only configurable bit is RACEN.
100 	 * All others must stay at zero (see function comment above.)
101 	 */
102 	if (vc->flags & OMAP_VC_CHANNEL_DEFAULT)
103 		vc->cfg_channel &= vc_cfg_bits->racen;
104 
105 	voltdm->rmw(CFG_CHANNEL_MASK << vc->cfg_channel_sa_shift,
106 		    vc->cfg_channel << vc->cfg_channel_sa_shift,
107 		    vc->cfg_channel_reg);
108 
109 	return 0;
110 }
111 
112 /* Voltage scale and accessory APIs */
113 int omap_vc_pre_scale(struct voltagedomain *voltdm,
114 		      unsigned long target_volt,
115 		      u8 *target_vsel, u8 *current_vsel)
116 {
117 	struct omap_vc_channel *vc = voltdm->vc;
118 	u32 vc_cmdval;
119 
120 	/* Check if sufficient pmic info is available for this vdd */
121 	if (!voltdm->pmic) {
122 		pr_err("%s: Insufficient pmic info to scale the vdd_%s\n",
123 			__func__, voltdm->name);
124 		return -EINVAL;
125 	}
126 
127 	if (!voltdm->pmic->uv_to_vsel) {
128 		pr_err("%s: PMIC function to convert voltage in uV to vsel not registered. Hence unable to scale voltage for vdd_%s\n",
129 		       __func__, voltdm->name);
130 		return -ENODATA;
131 	}
132 
133 	if (!voltdm->read || !voltdm->write) {
134 		pr_err("%s: No read/write API for accessing vdd_%s regs\n",
135 			__func__, voltdm->name);
136 		return -EINVAL;
137 	}
138 
139 	*target_vsel = voltdm->pmic->uv_to_vsel(target_volt);
140 	*current_vsel = voltdm->pmic->uv_to_vsel(voltdm->nominal_volt);
141 
142 	/* Setting the ON voltage to the new target voltage */
143 	vc_cmdval = voltdm->read(vc->cmdval_reg);
144 	vc_cmdval &= ~vc->common->cmd_on_mask;
145 	vc_cmdval |= (*target_vsel << vc->common->cmd_on_shift);
146 	voltdm->write(vc_cmdval, vc->cmdval_reg);
147 
148 	voltdm->vc_param->on = target_volt;
149 
150 	omap_vp_update_errorgain(voltdm, target_volt);
151 
152 	return 0;
153 }
154 
155 void omap_vc_post_scale(struct voltagedomain *voltdm,
156 			unsigned long target_volt,
157 			u8 target_vsel, u8 current_vsel)
158 {
159 	u32 smps_steps = 0, smps_delay = 0;
160 
161 	smps_steps = abs(target_vsel - current_vsel);
162 	/* SMPS slew rate / step size. 2us added as buffer. */
163 	smps_delay = ((smps_steps * voltdm->pmic->step_size) /
164 			voltdm->pmic->slew_rate) + 2;
165 	udelay(smps_delay);
166 }
167 
168 /* vc_bypass_scale - VC bypass method of voltage scaling */
169 int omap_vc_bypass_scale(struct voltagedomain *voltdm,
170 			 unsigned long target_volt)
171 {
172 	struct omap_vc_channel *vc = voltdm->vc;
173 	u32 loop_cnt = 0, retries_cnt = 0;
174 	u32 vc_valid, vc_bypass_val_reg, vc_bypass_value;
175 	u8 target_vsel, current_vsel;
176 	int ret;
177 
178 	ret = omap_vc_pre_scale(voltdm, target_volt, &target_vsel, &current_vsel);
179 	if (ret)
180 		return ret;
181 
182 	vc_valid = vc->common->valid;
183 	vc_bypass_val_reg = vc->common->bypass_val_reg;
184 	vc_bypass_value = (target_vsel << vc->common->data_shift) |
185 		(vc->volt_reg_addr << vc->common->regaddr_shift) |
186 		(vc->i2c_slave_addr << vc->common->slaveaddr_shift);
187 
188 	voltdm->write(vc_bypass_value, vc_bypass_val_reg);
189 	voltdm->write(vc_bypass_value | vc_valid, vc_bypass_val_reg);
190 
191 	vc_bypass_value = voltdm->read(vc_bypass_val_reg);
192 	/*
193 	 * Loop till the bypass command is acknowledged from the SMPS.
194 	 * NOTE: This is legacy code. The loop count and retry count needs
195 	 * to be revisited.
196 	 */
197 	while (!(vc_bypass_value & vc_valid)) {
198 		loop_cnt++;
199 
200 		if (retries_cnt > 10) {
201 			pr_warning("%s: Retry count exceeded\n", __func__);
202 			return -ETIMEDOUT;
203 		}
204 
205 		if (loop_cnt > 50) {
206 			retries_cnt++;
207 			loop_cnt = 0;
208 			udelay(10);
209 		}
210 		vc_bypass_value = voltdm->read(vc_bypass_val_reg);
211 	}
212 
213 	omap_vc_post_scale(voltdm, target_volt, target_vsel, current_vsel);
214 	return 0;
215 }
216 
217 /* Convert microsecond value to number of 32kHz clock cycles */
218 static inline u32 omap_usec_to_32k(u32 usec)
219 {
220 	return DIV_ROUND_UP_ULL(32768ULL * (u64)usec, 1000000ULL);
221 }
222 
223 /* Set oscillator setup time for omap3 */
224 static void omap3_set_clksetup(u32 usec, struct voltagedomain *voltdm)
225 {
226 	voltdm->write(omap_usec_to_32k(usec), OMAP3_PRM_CLKSETUP_OFFSET);
227 }
228 
229 /**
230  * omap3_set_i2c_timings - sets i2c sleep timings for a channel
231  * @voltdm: channel to configure
232  * @off_mode: select whether retention or off mode values used
233  *
234  * Calculates and sets up voltage controller to use I2C based
235  * voltage scaling for sleep modes. This can be used for either off mode
236  * or retention. Off mode has additionally an option to use sys_off_mode
237  * pad, which uses a global signal to program the whole power IC to
238  * off-mode.
239  */
240 static void omap3_set_i2c_timings(struct voltagedomain *voltdm, bool off_mode)
241 {
242 	unsigned long voltsetup1;
243 	u32 tgt_volt;
244 
245 	/*
246 	 * Oscillator is shut down only if we are using sys_off_mode pad,
247 	 * thus we set a minimal setup time here
248 	 */
249 	omap3_set_clksetup(1, voltdm);
250 
251 	if (off_mode)
252 		tgt_volt = voltdm->vc_param->off;
253 	else
254 		tgt_volt = voltdm->vc_param->ret;
255 
256 	voltsetup1 = (voltdm->vc_param->on - tgt_volt) /
257 			voltdm->pmic->slew_rate;
258 
259 	voltsetup1 = voltsetup1 * voltdm->sys_clk.rate / 8 / 1000000 + 1;
260 
261 	voltdm->rmw(voltdm->vfsm->voltsetup_mask,
262 		voltsetup1 << __ffs(voltdm->vfsm->voltsetup_mask),
263 		voltdm->vfsm->voltsetup_reg);
264 
265 	/*
266 	 * pmic is not controlling the voltage scaling during retention,
267 	 * thus set voltsetup2 to 0
268 	 */
269 	voltdm->write(0, OMAP3_PRM_VOLTSETUP2_OFFSET);
270 }
271 
272 /**
273  * omap3_set_off_timings - sets off-mode timings for a channel
274  * @voltdm: channel to configure
275  *
276  * Calculates and sets up off-mode timings for a channel. Off-mode
277  * can use either I2C based voltage scaling, or alternatively
278  * sys_off_mode pad can be used to send a global command to power IC.
279  * This function first checks which mode is being used, and calls
280  * omap3_set_i2c_timings() if the system is using I2C control mode.
281  * sys_off_mode has the additional benefit that voltages can be
282  * scaled to zero volt level with TWL4030 / TWL5030, I2C can only
283  * scale to 600mV.
284  */
285 static void omap3_set_off_timings(struct voltagedomain *voltdm)
286 {
287 	unsigned long clksetup;
288 	unsigned long voltsetup2;
289 	unsigned long voltsetup2_old;
290 	u32 val;
291 	u32 tstart, tshut;
292 
293 	/* check if sys_off_mode is used to control off-mode voltages */
294 	val = voltdm->read(OMAP3_PRM_VOLTCTRL_OFFSET);
295 	if (!(val & OMAP3430_SEL_OFF_MASK)) {
296 		/* No, omap is controlling them over I2C */
297 		omap3_set_i2c_timings(voltdm, true);
298 		return;
299 	}
300 
301 	omap_pm_get_oscillator(&tstart, &tshut);
302 	omap3_set_clksetup(tstart, voltdm);
303 
304 	clksetup = voltdm->read(OMAP3_PRM_CLKSETUP_OFFSET);
305 
306 	/* voltsetup 2 in us */
307 	voltsetup2 = voltdm->vc_param->on / voltdm->pmic->slew_rate;
308 
309 	/* convert to 32k clk cycles */
310 	voltsetup2 = DIV_ROUND_UP(voltsetup2 * 32768, 1000000);
311 
312 	voltsetup2_old = voltdm->read(OMAP3_PRM_VOLTSETUP2_OFFSET);
313 
314 	/*
315 	 * Update voltsetup2 if higher than current value (needed because
316 	 * we have multiple channels with different ramp times), also
317 	 * update voltoffset always to value recommended by TRM
318 	 */
319 	if (voltsetup2 > voltsetup2_old) {
320 		voltdm->write(voltsetup2, OMAP3_PRM_VOLTSETUP2_OFFSET);
321 		voltdm->write(clksetup - voltsetup2,
322 			OMAP3_PRM_VOLTOFFSET_OFFSET);
323 	} else
324 		voltdm->write(clksetup - voltsetup2_old,
325 			OMAP3_PRM_VOLTOFFSET_OFFSET);
326 
327 	/*
328 	 * omap is not controlling voltage scaling during off-mode,
329 	 * thus set voltsetup1 to 0
330 	 */
331 	voltdm->rmw(voltdm->vfsm->voltsetup_mask, 0,
332 		voltdm->vfsm->voltsetup_reg);
333 
334 	/* voltoffset must be clksetup minus voltsetup2 according to TRM */
335 	voltdm->write(clksetup - voltsetup2, OMAP3_PRM_VOLTOFFSET_OFFSET);
336 }
337 
338 static void __init omap3_vc_init_channel(struct voltagedomain *voltdm)
339 {
340 	omap3_set_off_timings(voltdm);
341 }
342 
343 /**
344  * omap4_calc_volt_ramp - calculates voltage ramping delays on omap4
345  * @voltdm: channel to calculate values for
346  * @voltage_diff: voltage difference in microvolts
347  *
348  * Calculates voltage ramp prescaler + counter values for a voltage
349  * difference on omap4. Returns a field value suitable for writing to
350  * VOLTSETUP register for a channel in following format:
351  * bits[8:9] prescaler ... bits[0:5] counter. See OMAP4 TRM for reference.
352  */
353 static u32 omap4_calc_volt_ramp(struct voltagedomain *voltdm, u32 voltage_diff)
354 {
355 	u32 prescaler;
356 	u32 cycles;
357 	u32 time;
358 
359 	time = voltage_diff / voltdm->pmic->slew_rate;
360 
361 	cycles = voltdm->sys_clk.rate / 1000 * time / 1000;
362 
363 	cycles /= 64;
364 	prescaler = 0;
365 
366 	/* shift to next prescaler until no overflow */
367 
368 	/* scale for div 256 = 64 * 4 */
369 	if (cycles > 63) {
370 		cycles /= 4;
371 		prescaler++;
372 	}
373 
374 	/* scale for div 512 = 256 * 2 */
375 	if (cycles > 63) {
376 		cycles /= 2;
377 		prescaler++;
378 	}
379 
380 	/* scale for div 2048 = 512 * 4 */
381 	if (cycles > 63) {
382 		cycles /= 4;
383 		prescaler++;
384 	}
385 
386 	/* check for overflow => invalid ramp time */
387 	if (cycles > 63) {
388 		pr_warn("%s: invalid setuptime for vdd_%s\n", __func__,
389 			voltdm->name);
390 		return 0;
391 	}
392 
393 	cycles++;
394 
395 	return (prescaler << OMAP4430_RAMP_UP_PRESCAL_SHIFT) |
396 		(cycles << OMAP4430_RAMP_UP_COUNT_SHIFT);
397 }
398 
399 /**
400  * omap4_usec_to_val_scrm - convert microsecond value to SCRM module bitfield
401  * @usec: microseconds
402  * @shift: number of bits to shift left
403  * @mask: bitfield mask
404  *
405  * Converts microsecond value to OMAP4 SCRM bitfield. Bitfield is
406  * shifted to requested position, and checked agains the mask value.
407  * If larger, forced to the max value of the field (i.e. the mask itself.)
408  * Returns the SCRM bitfield value.
409  */
410 static u32 omap4_usec_to_val_scrm(u32 usec, int shift, u32 mask)
411 {
412 	u32 val;
413 
414 	val = omap_usec_to_32k(usec) << shift;
415 
416 	/* Check for overflow, if yes, force to max value */
417 	if (val > mask)
418 		val = mask;
419 
420 	return val;
421 }
422 
423 /**
424  * omap4_set_timings - set voltage ramp timings for a channel
425  * @voltdm: channel to configure
426  * @off_mode: whether off-mode values are used
427  *
428  * Calculates and sets the voltage ramp up / down values for a channel.
429  */
430 static void omap4_set_timings(struct voltagedomain *voltdm, bool off_mode)
431 {
432 	u32 val;
433 	u32 ramp;
434 	int offset;
435 	u32 tstart, tshut;
436 
437 	if (off_mode) {
438 		ramp = omap4_calc_volt_ramp(voltdm,
439 			voltdm->vc_param->on - voltdm->vc_param->off);
440 		offset = voltdm->vfsm->voltsetup_off_reg;
441 	} else {
442 		ramp = omap4_calc_volt_ramp(voltdm,
443 			voltdm->vc_param->on - voltdm->vc_param->ret);
444 		offset = voltdm->vfsm->voltsetup_reg;
445 	}
446 
447 	if (!ramp)
448 		return;
449 
450 	val = voltdm->read(offset);
451 
452 	val |= ramp << OMAP4430_RAMP_DOWN_COUNT_SHIFT;
453 
454 	val |= ramp << OMAP4430_RAMP_UP_COUNT_SHIFT;
455 
456 	voltdm->write(val, offset);
457 
458 	omap_pm_get_oscillator(&tstart, &tshut);
459 
460 	val = omap4_usec_to_val_scrm(tstart, OMAP4_SETUPTIME_SHIFT,
461 		OMAP4_SETUPTIME_MASK);
462 	val |= omap4_usec_to_val_scrm(tshut, OMAP4_DOWNTIME_SHIFT,
463 		OMAP4_DOWNTIME_MASK);
464 
465 	__raw_writel(val, OMAP4_SCRM_CLKSETUPTIME);
466 }
467 
468 /* OMAP4 specific voltage init functions */
469 static void __init omap4_vc_init_channel(struct voltagedomain *voltdm)
470 {
471 	omap4_set_timings(voltdm, true);
472 	omap4_set_timings(voltdm, false);
473 }
474 
475 struct i2c_init_data {
476 	u8 loadbits;
477 	u8 load;
478 	u8 hsscll_38_4;
479 	u8 hsscll_26;
480 	u8 hsscll_19_2;
481 	u8 hsscll_16_8;
482 	u8 hsscll_12;
483 };
484 
485 static const __initdata struct i2c_init_data omap4_i2c_timing_data[] = {
486 	{
487 		.load = 50,
488 		.loadbits = 0x3,
489 		.hsscll_38_4 = 13,
490 		.hsscll_26 = 11,
491 		.hsscll_19_2 = 9,
492 		.hsscll_16_8 = 9,
493 		.hsscll_12 = 8,
494 	},
495 	{
496 		.load = 25,
497 		.loadbits = 0x2,
498 		.hsscll_38_4 = 13,
499 		.hsscll_26 = 11,
500 		.hsscll_19_2 = 9,
501 		.hsscll_16_8 = 9,
502 		.hsscll_12 = 8,
503 	},
504 	{
505 		.load = 12,
506 		.loadbits = 0x1,
507 		.hsscll_38_4 = 11,
508 		.hsscll_26 = 10,
509 		.hsscll_19_2 = 9,
510 		.hsscll_16_8 = 9,
511 		.hsscll_12 = 8,
512 	},
513 	{
514 		.load = 0,
515 		.loadbits = 0x0,
516 		.hsscll_38_4 = 12,
517 		.hsscll_26 = 10,
518 		.hsscll_19_2 = 9,
519 		.hsscll_16_8 = 8,
520 		.hsscll_12 = 8,
521 	},
522 };
523 
524 /**
525  * omap4_vc_i2c_timing_init - sets up board I2C timing parameters
526  * @voltdm: voltagedomain pointer to get data from
527  *
528  * Use PMIC + board supplied settings for calculating the total I2C
529  * channel capacitance and set the timing parameters based on this.
530  * Pre-calculated values are provided in data tables, as it is not
531  * too straightforward to calculate these runtime.
532  */
533 static void __init omap4_vc_i2c_timing_init(struct voltagedomain *voltdm)
534 {
535 	u32 capacitance;
536 	u32 val;
537 	u16 hsscll;
538 	const struct i2c_init_data *i2c_data;
539 
540 	if (!voltdm->pmic->i2c_high_speed) {
541 		pr_warn("%s: only high speed supported!\n", __func__);
542 		return;
543 	}
544 
545 	/* PCB trace capacitance, 0.125pF / mm => mm / 8 */
546 	capacitance = DIV_ROUND_UP(sr_i2c_pcb_length, 8);
547 
548 	/* OMAP pad capacitance */
549 	capacitance += 4;
550 
551 	/* PMIC pad capacitance */
552 	capacitance += voltdm->pmic->i2c_pad_load;
553 
554 	/* Search for capacitance match in the table */
555 	i2c_data = omap4_i2c_timing_data;
556 
557 	while (i2c_data->load > capacitance)
558 		i2c_data++;
559 
560 	/* Select proper values based on sysclk frequency */
561 	switch (voltdm->sys_clk.rate) {
562 	case 38400000:
563 		hsscll = i2c_data->hsscll_38_4;
564 		break;
565 	case 26000000:
566 		hsscll = i2c_data->hsscll_26;
567 		break;
568 	case 19200000:
569 		hsscll = i2c_data->hsscll_19_2;
570 		break;
571 	case 16800000:
572 		hsscll = i2c_data->hsscll_16_8;
573 		break;
574 	case 12000000:
575 		hsscll = i2c_data->hsscll_12;
576 		break;
577 	default:
578 		pr_warn("%s: unsupported sysclk rate: %d!\n", __func__,
579 			voltdm->sys_clk.rate);
580 		return;
581 	}
582 
583 	/* Loadbits define pull setup for the I2C channels */
584 	val = i2c_data->loadbits << 25 | i2c_data->loadbits << 29;
585 
586 	/* Write to SYSCTRL_PADCONF_WKUP_CTRL_I2C_2 to setup I2C pull */
587 	__raw_writel(val, OMAP2_L4_IO_ADDRESS(OMAP4_CTRL_MODULE_PAD_WKUP +
588 				OMAP4_CTRL_MODULE_PAD_WKUP_CONTROL_I2C_2));
589 
590 	/* HSSCLH can always be zero */
591 	val = hsscll << OMAP4430_HSSCLL_SHIFT;
592 	val |= (0x28 << OMAP4430_SCLL_SHIFT | 0x2c << OMAP4430_SCLH_SHIFT);
593 
594 	/* Write setup times to I2C config register */
595 	voltdm->write(val, OMAP4_PRM_VC_CFG_I2C_CLK_OFFSET);
596 }
597 
598 
599 
600 /**
601  * omap_vc_i2c_init - initialize I2C interface to PMIC
602  * @voltdm: voltage domain containing VC data
603  *
604  * Use PMIC supplied settings for I2C high-speed mode and
605  * master code (if set) and program the VC I2C configuration
606  * register.
607  *
608  * The VC I2C configuration is common to all VC channels,
609  * so this function only configures I2C for the first VC
610  * channel registers.  All other VC channels will use the
611  * same configuration.
612  */
613 static void __init omap_vc_i2c_init(struct voltagedomain *voltdm)
614 {
615 	struct omap_vc_channel *vc = voltdm->vc;
616 	static bool initialized;
617 	static bool i2c_high_speed;
618 	u8 mcode;
619 
620 	if (initialized) {
621 		if (voltdm->pmic->i2c_high_speed != i2c_high_speed)
622 			pr_warn("%s: I2C config for vdd_%s does not match other channels (%u).\n",
623 				__func__, voltdm->name, i2c_high_speed);
624 		return;
625 	}
626 
627 	i2c_high_speed = voltdm->pmic->i2c_high_speed;
628 	if (i2c_high_speed)
629 		voltdm->rmw(vc->common->i2c_cfg_hsen_mask,
630 			    vc->common->i2c_cfg_hsen_mask,
631 			    vc->common->i2c_cfg_reg);
632 
633 	mcode = voltdm->pmic->i2c_mcode;
634 	if (mcode)
635 		voltdm->rmw(vc->common->i2c_mcode_mask,
636 			    mcode << __ffs(vc->common->i2c_mcode_mask),
637 			    vc->common->i2c_cfg_reg);
638 
639 	if (cpu_is_omap44xx())
640 		omap4_vc_i2c_timing_init(voltdm);
641 
642 	initialized = true;
643 }
644 
645 /**
646  * omap_vc_calc_vsel - calculate vsel value for a channel
647  * @voltdm: channel to calculate value for
648  * @uvolt: microvolt value to convert to vsel
649  *
650  * Converts a microvolt value to vsel value for the used PMIC.
651  * This checks whether the microvolt value is out of bounds, and
652  * adjusts the value accordingly. If unsupported value detected,
653  * warning is thrown.
654  */
655 static u8 omap_vc_calc_vsel(struct voltagedomain *voltdm, u32 uvolt)
656 {
657 	if (voltdm->pmic->vddmin > uvolt)
658 		uvolt = voltdm->pmic->vddmin;
659 	if (voltdm->pmic->vddmax < uvolt) {
660 		WARN(1, "%s: voltage not supported by pmic: %u vs max %u\n",
661 			__func__, uvolt, voltdm->pmic->vddmax);
662 		/* Lets try maximum value anyway */
663 		uvolt = voltdm->pmic->vddmax;
664 	}
665 
666 	return voltdm->pmic->uv_to_vsel(uvolt);
667 }
668 
669 #ifdef CONFIG_PM
670 /**
671  * omap_pm_setup_sr_i2c_pcb_length - set length of SR I2C traces on PCB
672  * @mm: length of the PCB trace in millimetres
673  *
674  * Sets the PCB trace length for the I2C channel. By default uses 63mm.
675  * This is needed for properly calculating the capacitance value for
676  * the PCB trace, and for setting the SR I2C channel timing parameters.
677  */
678 void __init omap_pm_setup_sr_i2c_pcb_length(u32 mm)
679 {
680 	sr_i2c_pcb_length = mm;
681 }
682 #endif
683 
684 void __init omap_vc_init_channel(struct voltagedomain *voltdm)
685 {
686 	struct omap_vc_channel *vc = voltdm->vc;
687 	u8 on_vsel, onlp_vsel, ret_vsel, off_vsel;
688 	u32 val;
689 
690 	if (!voltdm->pmic || !voltdm->pmic->uv_to_vsel) {
691 		pr_err("%s: No PMIC info for vdd_%s\n", __func__, voltdm->name);
692 		return;
693 	}
694 
695 	if (!voltdm->read || !voltdm->write) {
696 		pr_err("%s: No read/write API for accessing vdd_%s regs\n",
697 			__func__, voltdm->name);
698 		return;
699 	}
700 
701 	vc->cfg_channel = 0;
702 	if (vc->flags & OMAP_VC_CHANNEL_CFG_MUTANT)
703 		vc_cfg_bits = &vc_mutant_channel_cfg;
704 	else
705 		vc_cfg_bits = &vc_default_channel_cfg;
706 
707 	/* get PMIC/board specific settings */
708 	vc->i2c_slave_addr = voltdm->pmic->i2c_slave_addr;
709 	vc->volt_reg_addr = voltdm->pmic->volt_reg_addr;
710 	vc->cmd_reg_addr = voltdm->pmic->cmd_reg_addr;
711 
712 	/* Configure the i2c slave address for this VC */
713 	voltdm->rmw(vc->smps_sa_mask,
714 		    vc->i2c_slave_addr << __ffs(vc->smps_sa_mask),
715 		    vc->smps_sa_reg);
716 	vc->cfg_channel |= vc_cfg_bits->sa;
717 
718 	/*
719 	 * Configure the PMIC register addresses.
720 	 */
721 	voltdm->rmw(vc->smps_volra_mask,
722 		    vc->volt_reg_addr << __ffs(vc->smps_volra_mask),
723 		    vc->smps_volra_reg);
724 	vc->cfg_channel |= vc_cfg_bits->rav;
725 
726 	if (vc->cmd_reg_addr) {
727 		voltdm->rmw(vc->smps_cmdra_mask,
728 			    vc->cmd_reg_addr << __ffs(vc->smps_cmdra_mask),
729 			    vc->smps_cmdra_reg);
730 		vc->cfg_channel |= vc_cfg_bits->rac;
731 	}
732 
733 	if (vc->cmd_reg_addr == vc->volt_reg_addr)
734 		vc->cfg_channel |= vc_cfg_bits->racen;
735 
736 	/* Set up the on, inactive, retention and off voltage */
737 	on_vsel = omap_vc_calc_vsel(voltdm, voltdm->vc_param->on);
738 	onlp_vsel = omap_vc_calc_vsel(voltdm, voltdm->vc_param->onlp);
739 	ret_vsel = omap_vc_calc_vsel(voltdm, voltdm->vc_param->ret);
740 	off_vsel = omap_vc_calc_vsel(voltdm, voltdm->vc_param->off);
741 
742 	val = ((on_vsel << vc->common->cmd_on_shift) |
743 	       (onlp_vsel << vc->common->cmd_onlp_shift) |
744 	       (ret_vsel << vc->common->cmd_ret_shift) |
745 	       (off_vsel << vc->common->cmd_off_shift));
746 	voltdm->write(val, vc->cmdval_reg);
747 	vc->cfg_channel |= vc_cfg_bits->cmd;
748 
749 	/* Channel configuration */
750 	omap_vc_config_channel(voltdm);
751 
752 	omap_vc_i2c_init(voltdm);
753 
754 	if (cpu_is_omap34xx())
755 		omap3_vc_init_channel(voltdm);
756 	else if (cpu_is_omap44xx())
757 		omap4_vc_init_channel(voltdm);
758 }
759 
760