2 * [origin: Linux kernel linux/arch/arm/mach-at91/clock.c]
4 * Copyright (C) 2011 Andreas Bießmann
5 * Copyright (C) 2005 David Brownell
6 * Copyright (C) 2005 Ivan Kokshaysky
7 * Copyright (C) 2009 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
16 #include <asm/arch/hardware.h>
17 #include <asm/arch/at91_pmc.h>
18 #include <asm/arch/clk.h>
20 #if !defined(CONFIG_AT91FAMILY)
21 # error You need to define CONFIG_AT91FAMILY in your board config!
24 DECLARE_GLOBAL_DATA_PTR
;
26 static unsigned long at91_css_to_rate(unsigned long css
)
29 case AT91_PMC_MCKR_CSS_SLOW
:
30 return CONFIG_SYS_AT91_SLOW_CLOCK
;
31 case AT91_PMC_MCKR_CSS_MAIN
:
32 return gd
->arch
.main_clk_rate_hz
;
33 case AT91_PMC_MCKR_CSS_PLLA
:
34 return gd
->arch
.plla_rate_hz
;
35 case AT91_PMC_MCKR_CSS_PLLB
:
36 return gd
->arch
.pllb_rate_hz
;
42 #ifdef CONFIG_USB_ATMEL
43 static unsigned at91_pll_calc(unsigned main_freq
, unsigned out_freq
)
45 unsigned i
, div
= 0, mul
= 0, diff
= 1 << 30;
46 unsigned ret
= (out_freq
> 155000000) ? 0xbe00 : 0x3e00;
48 /* PLL output max 240 MHz (or 180 MHz per errata) */
49 if (out_freq
> 240000000)
52 for (i
= 1; i
< 256; i
++) {
57 * PLL input between 1MHz and 32MHz per spec, but lower
58 * frequences seem necessary in some cases so allow 100K.
59 * Warning: some newer products need 2MHz min.
61 input
= main_freq
/ i
;
67 mul1
= out_freq
/ input
;
73 diff1
= out_freq
- input
* mul1
;
84 if (i
== 256 && diff
> (out_freq
>> 5))
86 return ret
| ((mul
- 1) << 16) | div
;
92 static u32
at91_pll_rate(u32 freq
, u32 reg
)
97 mul
= (reg
>> 16) & 0x7ff;
107 int at91_clock_init(unsigned long main_clock
)
110 at91_pmc_t
*pmc
= (at91_pmc_t
*) ATMEL_BASE_PMC
;
111 #ifndef CONFIG_SYS_AT91_MAIN_CLOCK
114 * When the bootloader initialized the main oscillator correctly,
115 * there's no problem using the cycle counter. But if it didn't,
116 * or when using oscillator bypass mode, we must be told the speed
121 tmp
= readl(&pmc
->mcfr
);
122 } while (!(tmp
& AT91_PMC_MCFR_MAINRDY
));
123 tmp
&= AT91_PMC_MCFR_MAINF_MASK
;
124 main_clock
= tmp
* (CONFIG_SYS_AT91_SLOW_CLOCK
/ 16);
127 gd
->arch
.main_clk_rate_hz
= main_clock
;
129 /* report if PLLA is more than mildly overclocked */
130 gd
->arch
.plla_rate_hz
= at91_pll_rate(main_clock
, readl(&pmc
->pllar
));
132 #ifdef CONFIG_USB_ATMEL
134 * USB clock init: choose 48 MHz PLLB value,
135 * disable 48MHz clock during usb peripheral suspend.
137 * REVISIT: assumes MCK doesn't derive from PLLB!
139 gd
->arch
.at91_pllb_usb_init
= at91_pll_calc(main_clock
, 48000000 * 2) |
140 AT91_PMC_PLLBR_USBDIV_2
;
141 gd
->arch
.pllb_rate_hz
= at91_pll_rate(main_clock
,
142 gd
->arch
.at91_pllb_usb_init
);
146 * MCK and CPU derive from one of those primary clocks.
147 * For now, assume this parentage won't change.
149 mckr
= readl(&pmc
->mckr
);
150 gd
->arch
.mck_rate_hz
= at91_css_to_rate(mckr
& AT91_PMC_MCKR_CSS_MASK
);
151 freq
= gd
->arch
.mck_rate_hz
;
153 freq
/= (1 << ((mckr
& AT91_PMC_MCKR_PRES_MASK
) >> 2)); /* prescale */
155 gd
->arch
.mck_rate_hz
= freq
/
156 (1 + ((mckr
& AT91_PMC_MCKR_MDIV_MASK
) >> 8));
157 gd
->arch
.cpu_clk_rate_hz
= freq
;