arch/arm/cpu/arm920t/at91/clock.c

   1 /*
   2  * [origin: Linux kernel linux/arch/arm/mach-at91/clock.c]
   3  *
   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>
   8  *
   9  * SPDX-License-Identifier:     GPL-2.0+
  10  */
  11 #include <common.h>
  12 #include <asm/io.h>
  13 #include <asm/arch/hardware.h>
  14 #include <asm/arch/at91_pmc.h>
  15 #include <asm/arch/clk.h>
  16
  17 #if !defined(CONFIG_AT91FAMILY)
  18 # error You need to define CONFIG_AT91FAMILY in your board config!
  19 #endif
  20
  21 DECLARE_GLOBAL_DATA_PTR;
  22
  23 static unsigned long at91_css_to_rate(unsigned long css)
  24 {
  25         switch (css) {
  26         case AT91_PMC_MCKR_CSS_SLOW:
  27                 return CONFIG_SYS_AT91_SLOW_CLOCK;
  28         case AT91_PMC_MCKR_CSS_MAIN:
  29                 return gd->arch.main_clk_rate_hz;
  30         case AT91_PMC_MCKR_CSS_PLLA:
  31                 return gd->arch.plla_rate_hz;
  32         case AT91_PMC_MCKR_CSS_PLLB:
  33                 return gd->arch.pllb_rate_hz;
  34         }
  35
  36         return 0;
  37 }
  38
  39 #ifdef CONFIG_USB_ATMEL
  40 static unsigned at91_pll_calc(unsigned main_freq, unsigned out_freq)
  41 {
  42         unsigned i, div = 0, mul = 0, diff = 1 << 30;
  43         unsigned ret = (out_freq > 155000000) ? 0xbe00 : 0x3e00;
  44
  45         /* PLL output max 240 MHz (or 180 MHz per errata) */
  46         if (out_freq > 240000000)
  47                 goto fail;
  48
  49         for (i = 1; i < 256; i++) {
  50                 int diff1;
  51                 unsigned input, mul1;
  52
  53                 /*
  54                  * PLL input between 1MHz and 32MHz per spec, but lower
  55                  * frequences seem necessary in some cases so allow 100K.
  56                  * Warning: some newer products need 2MHz min.
  57                  */
  58                 input = main_freq / i;
  59                 if (input < 100000)
  60                         continue;
  61                 if (input > 32000000)
  62                         continue;
  63
  64                 mul1 = out_freq / input;
  65                 if (mul1 > 2048)
  66                         continue;
  67                 if (mul1 < 2)
  68                         goto fail;
  69
  70                 diff1 = out_freq - input * mul1;
  71                 if (diff1 < 0)
  72                         diff1 = -diff1;
  73                 if (diff > diff1) {
  74                         diff = diff1;
  75                         div = i;
  76                         mul = mul1;
  77                         if (diff == 0)
  78                                 break;
  79                 }
  80         }
  81         if (i == 256 && diff > (out_freq >> 5))
  82                 goto fail;
  83         return ret | ((mul - 1) << 16) | div;
  84 fail:
  85         return 0;
  86 }
  87 #endif
  88
  89 static u32 at91_pll_rate(u32 freq, u32 reg)
  90 {
  91         unsigned mul, div;
  92
  93         div = reg & 0xff;
  94         mul = (reg >> 16) & 0x7ff;
  95         if (div && mul) {
  96                 freq /= div;
  97                 freq *= mul + 1;
  98         } else
  99                 freq = 0;
 100
 101         return freq;
 102 }
 103
 104 int at91_clock_init(unsigned long main_clock)
 105 {
 106         unsigned freq, mckr;
 107         at91_pmc_t *pmc = (at91_pmc_t *) ATMEL_BASE_PMC;
 108 #ifndef CONFIG_SYS_AT91_MAIN_CLOCK
 109         unsigned tmp;
 110         /*
 111          * When the bootloader initialized the main oscillator correctly,
 112          * there's no problem using the cycle counter.  But if it didn't,
 113          * or when using oscillator bypass mode, we must be told the speed
 114          * of the main clock.
 115          */
 116         if (!main_clock) {
 117                 do {
 118                         tmp = readl(&pmc->mcfr);
 119                 } while (!(tmp & AT91_PMC_MCFR_MAINRDY));
 120                 tmp &= AT91_PMC_MCFR_MAINF_MASK;
 121                 main_clock = tmp * (CONFIG_SYS_AT91_SLOW_CLOCK / 16);
 122         }
 123 #endif
 124         gd->arch.main_clk_rate_hz = main_clock;
 125
 126         /* report if PLLA is more than mildly overclocked */
 127         gd->arch.plla_rate_hz = at91_pll_rate(main_clock, readl(&pmc->pllar));
 128
 129 #ifdef CONFIG_USB_ATMEL
 130         /*
 131          * USB clock init:  choose 48 MHz PLLB value,
 132          * disable 48MHz clock during usb peripheral suspend.
 133          *
 134          * REVISIT:  assumes MCK doesn't derive from PLLB!
 135          */
 136         gd->arch.at91_pllb_usb_init = at91_pll_calc(main_clock, 48000000 * 2) |
 137                              AT91_PMC_PLLBR_USBDIV_2;
 138         gd->arch.pllb_rate_hz = at91_pll_rate(main_clock,
 139                                               gd->arch.at91_pllb_usb_init);
 140 #endif
 141
 142         /*
 143          * MCK and CPU derive from one of those primary clocks.
 144          * For now, assume this parentage won't change.
 145          */
 146         mckr = readl(&pmc->mckr);
 147         gd->arch.mck_rate_hz = at91_css_to_rate(mckr & AT91_PMC_MCKR_CSS_MASK);
 148         freq = gd->arch.mck_rate_hz;
 149
 150         freq /= (1 << ((mckr & AT91_PMC_MCKR_PRES_MASK) >> 2)); /* prescale */
 151         /* mdiv */
 152         gd->arch.mck_rate_hz = freq /
 153                         (1 + ((mckr & AT91_PMC_MCKR_MDIV_MASK) >> 8));
 154         gd->arch.cpu_clk_rate_hz = freq;
 155
 156         return 0;
 157 }