Linux Audio

Check our new training course

Embedded Linux Audio

Check our new training course
with Creative Commons CC-BY-SA
lecture materials

Bootlin logo

Elixir Cross Referencer

Loading...
  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
/***************************************************************************/

/*
 *	linux/arch/m68knommu/platform/532x/config.c
 *
 *	Copyright (C) 1999-2002, Greg Ungerer (gerg@snapgear.com)
 *	Copyright (C) 2000, Lineo (www.lineo.com)
 *	Yaroslav Vinogradov yaroslav.vinogradov@freescale.com
 *	Copyright Freescale Semiconductor, Inc 2006
 *	Copyright (c) 2006, emlix, Sebastian Hess <shess@hessware.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

/***************************************************************************/

#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/init.h>
#include <linux/io.h>
#include <asm/machdep.h>
#include <asm/coldfire.h>
#include <asm/mcfsim.h>
#include <asm/mcfuart.h>
#include <asm/mcfdma.h>
#include <asm/mcfwdebug.h>
#include <asm/mcfclk.h>

/***************************************************************************/

DEFINE_CLK(0, "flexbus", 2, MCF_CLK);
DEFINE_CLK(0, "mcfcan.0", 8, MCF_CLK);
DEFINE_CLK(0, "fec.0", 12, MCF_CLK);
DEFINE_CLK(0, "edma", 17, MCF_CLK);
DEFINE_CLK(0, "intc.0", 18, MCF_CLK);
DEFINE_CLK(0, "intc.1", 19, MCF_CLK);
DEFINE_CLK(0, "iack.0", 21, MCF_CLK);
DEFINE_CLK(0, "mcfi2c.0", 22, MCF_CLK);
DEFINE_CLK(0, "mcfqspi.0", 23, MCF_CLK);
DEFINE_CLK(0, "mcfuart.0", 24, MCF_BUSCLK);
DEFINE_CLK(0, "mcfuart.1", 25, MCF_BUSCLK);
DEFINE_CLK(0, "mcfuart.2", 26, MCF_BUSCLK);
DEFINE_CLK(0, "mcftmr.0", 28, MCF_CLK);
DEFINE_CLK(0, "mcftmr.1", 29, MCF_CLK);
DEFINE_CLK(0, "mcftmr.2", 30, MCF_CLK);
DEFINE_CLK(0, "mcftmr.3", 31, MCF_CLK);

DEFINE_CLK(0, "mcfpit.0", 32, MCF_CLK);
DEFINE_CLK(0, "mcfpit.1", 33, MCF_CLK);
DEFINE_CLK(0, "mcfpit.2", 34, MCF_CLK);
DEFINE_CLK(0, "mcfpit.3", 35, MCF_CLK);
DEFINE_CLK(0, "mcfpwm.0", 36, MCF_CLK);
DEFINE_CLK(0, "mcfeport.0", 37, MCF_CLK);
DEFINE_CLK(0, "mcfwdt.0", 38, MCF_CLK);
DEFINE_CLK(0, "sys.0", 40, MCF_BUSCLK);
DEFINE_CLK(0, "gpio.0", 41, MCF_BUSCLK);
DEFINE_CLK(0, "mcfrtc.0", 42, MCF_CLK);
DEFINE_CLK(0, "mcflcd.0", 43, MCF_CLK);
DEFINE_CLK(0, "mcfusb-otg.0", 44, MCF_CLK);
DEFINE_CLK(0, "mcfusb-host.0", 45, MCF_CLK);
DEFINE_CLK(0, "sdram.0", 46, MCF_CLK);
DEFINE_CLK(0, "ssi.0", 47, MCF_CLK);
DEFINE_CLK(0, "pll.0", 48, MCF_CLK);

DEFINE_CLK(1, "mdha.0", 32, MCF_CLK);
DEFINE_CLK(1, "skha.0", 33, MCF_CLK);
DEFINE_CLK(1, "rng.0", 34, MCF_CLK);

struct clk *mcf_clks[] = {
	&__clk_0_2,	/* flexbus */
	&__clk_0_8,	/* mcfcan.0 */
	&__clk_0_12,	/* fec.0 */
	&__clk_0_17,	/* edma */
	&__clk_0_18,	/* intc.0 */
	&__clk_0_19,	/* intc.1 */
	&__clk_0_21,	/* iack.0 */
	&__clk_0_22,	/* mcfi2c.0 */
	&__clk_0_23,	/* mcfqspi.0 */
	&__clk_0_24,	/* mcfuart.0 */
	&__clk_0_25,	/* mcfuart.1 */
	&__clk_0_26,	/* mcfuart.2 */
	&__clk_0_28,	/* mcftmr.0 */
	&__clk_0_29,	/* mcftmr.1 */
	&__clk_0_30,	/* mcftmr.2 */
	&__clk_0_31,	/* mcftmr.3 */

	&__clk_0_32,	/* mcfpit.0 */
	&__clk_0_33,	/* mcfpit.1 */
	&__clk_0_34,	/* mcfpit.2 */
	&__clk_0_35,	/* mcfpit.3 */
	&__clk_0_36,	/* mcfpwm.0 */
	&__clk_0_37,	/* mcfeport.0 */
	&__clk_0_38,	/* mcfwdt.0 */
	&__clk_0_40,	/* sys.0 */
	&__clk_0_41,	/* gpio.0 */
	&__clk_0_42,	/* mcfrtc.0 */
	&__clk_0_43,	/* mcflcd.0 */
	&__clk_0_44,	/* mcfusb-otg.0 */
	&__clk_0_45,	/* mcfusb-host.0 */
	&__clk_0_46,	/* sdram.0 */
	&__clk_0_47,	/* ssi.0 */
	&__clk_0_48,	/* pll.0 */

	&__clk_1_32,	/* mdha.0 */
	&__clk_1_33,	/* skha.0 */
	&__clk_1_34,	/* rng.0 */
	NULL,
};

static struct clk * const enable_clks[] __initconst = {
	&__clk_0_2,	/* flexbus */
	&__clk_0_18,	/* intc.0 */
	&__clk_0_19,	/* intc.1 */
	&__clk_0_21,	/* iack.0 */
	&__clk_0_24,	/* mcfuart.0 */
	&__clk_0_25,	/* mcfuart.1 */
	&__clk_0_26,	/* mcfuart.2 */

	&__clk_0_32,	/* mcfpit.0 */
	&__clk_0_33,	/* mcfpit.1 */
	&__clk_0_37,	/* mcfeport.0 */
	&__clk_0_40,	/* sys.0 */
	&__clk_0_41,	/* gpio.0 */
	&__clk_0_46,	/* sdram.0 */
	&__clk_0_48,	/* pll.0 */
};

static struct clk * const disable_clks[] __initconst = {
	&__clk_0_8,	/* mcfcan.0 */
	&__clk_0_12,	/* fec.0 */
	&__clk_0_17,	/* edma */
	&__clk_0_22,	/* mcfi2c.0 */
	&__clk_0_23,	/* mcfqspi.0 */
	&__clk_0_28,	/* mcftmr.0 */
	&__clk_0_29,	/* mcftmr.1 */
	&__clk_0_30,	/* mcftmr.2 */
	&__clk_0_31,	/* mcftmr.3 */
	&__clk_0_34,	/* mcfpit.2 */
	&__clk_0_35,	/* mcfpit.3 */
	&__clk_0_36,	/* mcfpwm.0 */
	&__clk_0_38,	/* mcfwdt.0 */
	&__clk_0_42,	/* mcfrtc.0 */
	&__clk_0_43,	/* mcflcd.0 */
	&__clk_0_44,	/* mcfusb-otg.0 */
	&__clk_0_45,	/* mcfusb-host.0 */
	&__clk_0_47,	/* ssi.0 */
	&__clk_1_32,	/* mdha.0 */
	&__clk_1_33,	/* skha.0 */
	&__clk_1_34,	/* rng.0 */
};


static void __init m532x_clk_init(void)
{
	unsigned i;

	/* make sure these clocks are enabled */
	for (i = 0; i < ARRAY_SIZE(enable_clks); ++i)
		__clk_init_enabled(enable_clks[i]);
	/* make sure these clocks are disabled */
	for (i = 0; i < ARRAY_SIZE(disable_clks); ++i)
		__clk_init_disabled(disable_clks[i]);
}

/***************************************************************************/

#if IS_ENABLED(CONFIG_SPI_COLDFIRE_QSPI)

static void __init m532x_qspi_init(void)
{
	/* setup QSPS pins for QSPI with gpio CS control */
	writew(0x01f0, MCFGPIO_PAR_QSPI);
}

#endif /* IS_ENABLED(CONFIG_SPI_COLDFIRE_QSPI) */

/***************************************************************************/

static void __init m532x_uarts_init(void)
{
	/* UART GPIO initialization */
	writew(readw(MCFGPIO_PAR_UART) | 0x0FFF, MCFGPIO_PAR_UART);
}

/***************************************************************************/

static void __init m532x_fec_init(void)
{
	u8 v;

	/* Set multi-function pins to ethernet mode for fec0 */
	v = readb(MCFGPIO_PAR_FECI2C);
	v |= MCF_GPIO_PAR_FECI2C_PAR_MDC_EMDC |
		MCF_GPIO_PAR_FECI2C_PAR_MDIO_EMDIO;
	writeb(v, MCFGPIO_PAR_FECI2C);

	v = readb(MCFGPIO_PAR_FEC);
	v = MCF_GPIO_PAR_FEC_PAR_FEC_7W_FEC | MCF_GPIO_PAR_FEC_PAR_FEC_MII_FEC;
	writeb(v, MCFGPIO_PAR_FEC);
}

/***************************************************************************/

void __init config_BSP(char *commandp, int size)
{
#if !defined(CONFIG_BOOTPARAM)
	/* Copy command line from FLASH to local buffer... */
	memcpy(commandp, (char *) 0x4000, 4);
	if(strncmp(commandp, "kcl ", 4) == 0){
		memcpy(commandp, (char *) 0x4004, size);
		commandp[size-1] = 0;
	} else {
		memset(commandp, 0, size);
	}
#endif
	mach_sched_init = hw_timer_init;
	m532x_clk_init();
	m532x_uarts_init();
	m532x_fec_init();
#if IS_ENABLED(CONFIG_SPI_COLDFIRE_QSPI)
	m532x_qspi_init();
#endif

#ifdef CONFIG_BDM_DISABLE
	/*
	 * Disable the BDM clocking.  This also turns off most of the rest of
	 * the BDM device.  This is good for EMC reasons. This option is not
	 * incompatible with the memory protection option.
	 */
	wdebug(MCFDEBUG_CSR, MCFDEBUG_CSR_PSTCLK);
#endif
}

/***************************************************************************/
/* Board initialization */
/***************************************************************************/
/* 
 * PLL min/max specifications
 */
#define MAX_FVCO	500000	/* KHz */
#define MAX_FSYS	80000 	/* KHz */
#define MIN_FSYS	58333 	/* KHz */
#define FREF		16000   /* KHz */


#define MAX_MFD		135     /* Multiplier */
#define MIN_MFD		88      /* Multiplier */
#define BUSDIV		6       /* Divider */

/*
 * Low Power Divider specifications
 */
#define MIN_LPD		(1 << 0)    /* Divider (not encoded) */
#define MAX_LPD		(1 << 15)   /* Divider (not encoded) */
#define DEFAULT_LPD	(1 << 1)	/* Divider (not encoded) */

#define SYS_CLK_KHZ	80000
#define SYSTEM_PERIOD	12.5
/*
 *  SDRAM Timing Parameters
 */  
#define SDRAM_BL	8	/* # of beats in a burst */
#define SDRAM_TWR	2	/* in clocks */
#define SDRAM_CASL	2.5	/* CASL in clocks */
#define SDRAM_TRCD	2	/* in clocks */
#define SDRAM_TRP	2	/* in clocks */
#define SDRAM_TRFC	7	/* in clocks */
#define SDRAM_TREFI	7800	/* in ns */

#define EXT_SRAM_ADDRESS	(0xC0000000)
#define FLASH_ADDRESS		(0x00000000)
#define SDRAM_ADDRESS		(0x40000000)

#define NAND_FLASH_ADDRESS	(0xD0000000)

int sys_clk_khz = 0;
int sys_clk_mhz = 0;

void wtm_init(void);
void scm_init(void);
void gpio_init(void);
void fbcs_init(void);
void sdramc_init(void);
int  clock_pll (int fsys, int flags);
int  clock_limp (int);
int  clock_exit_limp (void);
int  get_sys_clock (void);

asmlinkage void __init sysinit(void)
{
	sys_clk_khz = clock_pll(0, 0);
	sys_clk_mhz = sys_clk_khz/1000;
	
	wtm_init();
	scm_init();
	gpio_init();
	fbcs_init();
	sdramc_init();
}

void wtm_init(void)
{
	/* Disable watchdog timer */
	writew(0, MCF_WTM_WCR);
}

#define MCF_SCM_BCR_GBW		(0x00000100)
#define MCF_SCM_BCR_GBR		(0x00000200)

void scm_init(void)
{
	/* All masters are trusted */
	writel(0x77777777, MCF_SCM_MPR);
    
	/* Allow supervisor/user, read/write, and trusted/untrusted
	   access to all slaves */
	writel(0, MCF_SCM_PACRA);
	writel(0, MCF_SCM_PACRB);
	writel(0, MCF_SCM_PACRC);
	writel(0, MCF_SCM_PACRD);
	writel(0, MCF_SCM_PACRE);
	writel(0, MCF_SCM_PACRF);

	/* Enable bursts */
	writel(MCF_SCM_BCR_GBR | MCF_SCM_BCR_GBW, MCF_SCM_BCR);
}


void fbcs_init(void)
{
	writeb(0x3E, MCFGPIO_PAR_CS);

	/* Latch chip select */
	writel(0x10080000, MCF_FBCS1_CSAR);

	writel(0x002A3780, MCF_FBCS1_CSCR);
	writel(MCF_FBCS_CSMR_BAM_2M | MCF_FBCS_CSMR_V, MCF_FBCS1_CSMR);

	/* Initialize latch to drive signals to inactive states */
	writew(0xffff, 0x10080000);

	/* External SRAM */
	writel(EXT_SRAM_ADDRESS, MCF_FBCS1_CSAR);
	writel(MCF_FBCS_CSCR_PS_16 |
		MCF_FBCS_CSCR_AA |
		MCF_FBCS_CSCR_SBM |
		MCF_FBCS_CSCR_WS(1),
		MCF_FBCS1_CSCR);
	writel(MCF_FBCS_CSMR_BAM_512K | MCF_FBCS_CSMR_V, MCF_FBCS1_CSMR);

	/* Boot Flash connected to FBCS0 */
	writel(FLASH_ADDRESS, MCF_FBCS0_CSAR);
	writel(MCF_FBCS_CSCR_PS_16 |
		MCF_FBCS_CSCR_BEM |
		MCF_FBCS_CSCR_AA |
		MCF_FBCS_CSCR_SBM |
		MCF_FBCS_CSCR_WS(7),
		MCF_FBCS0_CSCR);
	writel(MCF_FBCS_CSMR_BAM_32M | MCF_FBCS_CSMR_V, MCF_FBCS0_CSMR);
}

void sdramc_init(void)
{
	/*
	 * Check to see if the SDRAM has already been initialized
	 * by a run control tool
	 */
	if (!(readl(MCF_SDRAMC_SDCR) & MCF_SDRAMC_SDCR_REF)) {
		/* SDRAM chip select initialization */
		
		/* Initialize SDRAM chip select */
		writel(MCF_SDRAMC_SDCS_BA(SDRAM_ADDRESS) |
			MCF_SDRAMC_SDCS_CSSZ(MCF_SDRAMC_SDCS_CSSZ_32MBYTE),
			MCF_SDRAMC_SDCS0);

	/*
	 * Basic configuration and initialization
	 */
	writel(MCF_SDRAMC_SDCFG1_SRD2RW((int)((SDRAM_CASL + 2) + 0.5)) |
		MCF_SDRAMC_SDCFG1_SWT2RD(SDRAM_TWR + 1) |
		MCF_SDRAMC_SDCFG1_RDLAT((int)((SDRAM_CASL * 2) + 2)) |
		MCF_SDRAMC_SDCFG1_ACT2RW((int)(SDRAM_TRCD + 0.5)) |
		MCF_SDRAMC_SDCFG1_PRE2ACT((int)(SDRAM_TRP + 0.5)) |
		MCF_SDRAMC_SDCFG1_REF2ACT((int)(SDRAM_TRFC + 0.5)) |
		MCF_SDRAMC_SDCFG1_WTLAT(3),
		MCF_SDRAMC_SDCFG1);
	writel(MCF_SDRAMC_SDCFG2_BRD2PRE(SDRAM_BL / 2 + 1) |
		MCF_SDRAMC_SDCFG2_BWT2RW(SDRAM_BL / 2 + SDRAM_TWR) |
		MCF_SDRAMC_SDCFG2_BRD2WT((int)((SDRAM_CASL + SDRAM_BL / 2 - 1.0) + 0.5)) |
		MCF_SDRAMC_SDCFG2_BL(SDRAM_BL - 1),
		MCF_SDRAMC_SDCFG2);

            
	/*
	 * Precharge and enable write to SDMR
	 */
	writel(MCF_SDRAMC_SDCR_MODE_EN |
		MCF_SDRAMC_SDCR_CKE |
		MCF_SDRAMC_SDCR_DDR |
		MCF_SDRAMC_SDCR_MUX(1) |
		MCF_SDRAMC_SDCR_RCNT((int)(((SDRAM_TREFI / (SYSTEM_PERIOD * 64)) - 1) + 0.5)) |
		MCF_SDRAMC_SDCR_PS_16 |
		MCF_SDRAMC_SDCR_IPALL,
		MCF_SDRAMC_SDCR);

	/*
	 * Write extended mode register
	 */
	writel(MCF_SDRAMC_SDMR_BNKAD_LEMR |
		MCF_SDRAMC_SDMR_AD(0x0) |
		MCF_SDRAMC_SDMR_CMD,
		MCF_SDRAMC_SDMR);

	/*
	 * Write mode register and reset DLL
	 */
	writel(MCF_SDRAMC_SDMR_BNKAD_LMR |
		MCF_SDRAMC_SDMR_AD(0x163) |
		MCF_SDRAMC_SDMR_CMD,
		MCF_SDRAMC_SDMR);

	/*
	 * Execute a PALL command
	 */
	writel(readl(MCF_SDRAMC_SDCR) | MCF_SDRAMC_SDCR_IPALL, MCF_SDRAMC_SDCR);

	/*
	 * Perform two REF cycles
	 */
	writel(readl(MCF_SDRAMC_SDCR) | MCF_SDRAMC_SDCR_IREF, MCF_SDRAMC_SDCR);
	writel(readl(MCF_SDRAMC_SDCR) | MCF_SDRAMC_SDCR_IREF, MCF_SDRAMC_SDCR);

	/*
	 * Write mode register and clear reset DLL
	 */
	writel(MCF_SDRAMC_SDMR_BNKAD_LMR |
		MCF_SDRAMC_SDMR_AD(0x063) |
		MCF_SDRAMC_SDMR_CMD,
		MCF_SDRAMC_SDMR);
				
	/*
	 * Enable auto refresh and lock SDMR
	 */
	writel(readl(MCF_SDRAMC_SDCR) & ~MCF_SDRAMC_SDCR_MODE_EN,
		MCF_SDRAMC_SDCR);
	writel(MCF_SDRAMC_SDCR_REF | MCF_SDRAMC_SDCR_DQS_OE(0xC),
		MCF_SDRAMC_SDCR);
	}
}

void gpio_init(void)
{
	/* Enable UART0 pins */
	writew(MCF_GPIO_PAR_UART_PAR_URXD0 | MCF_GPIO_PAR_UART_PAR_UTXD0,
		MCFGPIO_PAR_UART);

	/*
	 * Initialize TIN3 as a GPIO output to enable the write
	 * half of the latch.
	 */
	writeb(0x00, MCFGPIO_PAR_TIMER);
	writeb(0x08, MCFGPIO_PDDR_TIMER);
	writeb(0x00, MCFGPIO_PCLRR_TIMER);
}

int clock_pll(int fsys, int flags)
{
	int fref, temp, fout, mfd;
	u32 i;

	fref = FREF;
        
	if (fsys == 0) {
		/* Return current PLL output */
		mfd = readb(MCF_PLL_PFDR);

		return (fref * mfd / (BUSDIV * 4));
	}

	/* Check bounds of requested system clock */
	if (fsys > MAX_FSYS)
		fsys = MAX_FSYS;
	if (fsys < MIN_FSYS)
		fsys = MIN_FSYS;

	/* Multiplying by 100 when calculating the temp value,
	   and then dividing by 100 to calculate the mfd allows
	   for exact values without needing to include floating
	   point libraries. */
	temp = 100 * fsys / fref;
	mfd = 4 * BUSDIV * temp / 100;
    	    	    	
	/* Determine the output frequency for selected values */
	fout = (fref * mfd / (BUSDIV * 4));

	/*
	 * Check to see if the SDRAM has already been initialized.
	 * If it has then the SDRAM needs to be put into self refresh
	 * mode before reprogramming the PLL.
	 */
	if (readl(MCF_SDRAMC_SDCR) & MCF_SDRAMC_SDCR_REF)
		/* Put SDRAM into self refresh mode */
		writel(readl(MCF_SDRAMC_SDCR) & ~MCF_SDRAMC_SDCR_CKE,
			MCF_SDRAMC_SDCR);

	/*
	 * Initialize the PLL to generate the new system clock frequency.
	 * The device must be put into LIMP mode to reprogram the PLL.
	 */

	/* Enter LIMP mode */
	clock_limp(DEFAULT_LPD);
     					
	/* Reprogram PLL for desired fsys */
	writeb(MCF_PLL_PODR_CPUDIV(BUSDIV/3) | MCF_PLL_PODR_BUSDIV(BUSDIV),
		MCF_PLL_PODR);
						
	writeb(mfd, MCF_PLL_PFDR);
		
	/* Exit LIMP mode */
	clock_exit_limp();
	
	/*
	 * Return the SDRAM to normal operation if it is in use.
	 */
	if (readl(MCF_SDRAMC_SDCR) & MCF_SDRAMC_SDCR_REF)
		/* Exit self refresh mode */
		writel(readl(MCF_SDRAMC_SDCR) | MCF_SDRAMC_SDCR_CKE,
			MCF_SDRAMC_SDCR);

	/* Errata - workaround for SDRAM opeartion after exiting LIMP mode */
	writel(MCF_SDRAMC_REFRESH, MCF_SDRAMC_LIMP_FIX);

	/* wait for DQS logic to relock */
	for (i = 0; i < 0x200; i++)
		;

	return fout;
}

int clock_limp(int div)
{
	u32 temp;

	/* Check bounds of divider */
	if (div < MIN_LPD)
		div = MIN_LPD;
	if (div > MAX_LPD)
		div = MAX_LPD;
    
	/* Save of the current value of the SSIDIV so we don't
	   overwrite the value*/
	temp = readw(MCF_CCM_CDR) & MCF_CCM_CDR_SSIDIV(0xF);
      
	/* Apply the divider to the system clock */
	writew(MCF_CCM_CDR_LPDIV(div) | MCF_CCM_CDR_SSIDIV(temp), MCF_CCM_CDR);
    
	writew(readw(MCF_CCM_MISCCR) | MCF_CCM_MISCCR_LIMP, MCF_CCM_MISCCR);
    
	return (FREF/(3*(1 << div)));
}

int clock_exit_limp(void)
{
	int fout;
	
	/* Exit LIMP mode */
	writew(readw(MCF_CCM_MISCCR) & ~MCF_CCM_MISCCR_LIMP, MCF_CCM_MISCCR);

	/* Wait for PLL to lock */
	while (!(readw(MCF_CCM_MISCCR) & MCF_CCM_MISCCR_PLL_LOCK))
		;
	
	fout = get_sys_clock();

	return fout;
}

int get_sys_clock(void)
{
	int divider;
	
	/* Test to see if device is in LIMP mode */
	if (readw(MCF_CCM_MISCCR) & MCF_CCM_MISCCR_LIMP) {
		divider = readw(MCF_CCM_CDR) & MCF_CCM_CDR_LPDIV(0xF);
		return (FREF/(2 << divider));
	}
	else
		return (FREF * readb(MCF_PLL_PFDR)) / (BUSDIV * 4);
}