arch/arm/cpu/arm926ejs/at91/clock.c

   1 /*
   2  * [origin: Linux kernel linux/arch/arm/mach-at91/clock.c]
   3  *
   4  * Copyright (C) 2005 David Brownell
   5  * Copyright (C) 2005 Ivan Kokshaysky
   6  * Copyright (C) 2009 Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
   7  *
   8  * SPDX-License-Identifier:     GPL-2.0+
   9  */
  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 defined(CONFIG_AT91SAM9G20)
  60                 if (input < 2000000)
  61                         continue;
  62 #endif
  63                 if (input < 100000)
  64                         continue;
  65                 if (input > 32000000)
  66                         continue;
  67
  68                 mul1 = out_freq / input;
  69 #if defined(CONFIG_AT91SAM9G20)
  70                 if (mul > 63)
  71                         continue;
  72 #endif
  73                 if (mul1 > 2048)
  74                         continue;
  75                 if (mul1 < 2)
  76                         goto fail;
  77
  78                 diff1 = out_freq - input * mul1;
  79                 if (diff1 < 0)
  80                         diff1 = -diff1;
  81                 if (diff > diff1) {
  82                         diff = diff1;
  83                         div = i;
  84                         mul = mul1;
  85                         if (diff == 0)
  86                                 break;
  87                 }
  88         }
  89         if (i == 256 && diff > (out_freq >> 5))
  90                 goto fail;
  91         return ret | ((mul - 1) << 16) | div;
  92 fail:
  93         return 0;
  94 }
  95 #endif
  96
  97 static u32 at91_pll_rate(u32 freq, u32 reg)
  98 {
  99         unsigned mul, div;
 100
 101         div = reg & 0xff;
 102         mul = (reg >> 16) & 0x7ff;
 103         if (div && mul) {
 104                 freq /= div;
 105                 freq *= mul + 1;
 106         } else
 107                 freq = 0;
 108
 109         return freq;
 110 }
 111
 112 int at91_clock_init(unsigned long main_clock)
 113 {
 114         unsigned freq, mckr;
 115         at91_pmc_t *pmc = (at91_pmc_t *) ATMEL_BASE_PMC;
 116 #ifndef CONFIG_SYS_AT91_MAIN_CLOCK
 117         unsigned tmp;
 118         /*
 119          * When the bootloader initialized the main oscillator correctly,
 120          * there's no problem using the cycle counter.  But if it didn't,
 121          * or when using oscillator bypass mode, we must be told the speed
 122          * of the main clock.
 123          */
 124         if (!main_clock) {
 125                 do {
 126                         tmp = readl(&pmc->mcfr);
 127                 } while (!(tmp & AT91_PMC_MCFR_MAINRDY));
 128                 tmp &= AT91_PMC_MCFR_MAINF_MASK;
 129                 main_clock = tmp * (CONFIG_SYS_AT91_SLOW_CLOCK / 16);
 130         }
 131 #endif
 132         gd->arch.main_clk_rate_hz = main_clock;
 133
 134         /* report if PLLA is more than mildly overclocked */
 135         gd->arch.plla_rate_hz = at91_pll_rate(main_clock, readl(&pmc->pllar));
 136
 137 #ifdef CONFIG_USB_ATMEL
 138         /*
 139          * USB clock init:  choose 48 MHz PLLB value,
 140          * disable 48MHz clock during usb peripheral suspend.
 141          *
 142          * REVISIT:  assumes MCK doesn't derive from PLLB!
 143          */
 144         gd->arch.at91_pllb_usb_init = at91_pll_calc(main_clock, 48000000 * 2) |
 145                              AT91_PMC_PLLBR_USBDIV_2;
 146         gd->arch.pllb_rate_hz = at91_pll_rate(main_clock,
 147                                               gd->arch.at91_pllb_usb_init);
 148 #endif
 149
 150         /*
 151          * MCK and CPU derive from one of those primary clocks.
 152          * For now, assume this parentage won't change.
 153          */
 154         mckr = readl(&pmc->mckr);
 155 #if defined(CONFIG_AT91SAM9G45) || defined(CONFIG_AT91SAM9M10G45) \
 156                 || defined(CONFIG_AT91SAM9N12) || defined(CONFIG_AT91SAM9X5)
 157         /* plla divisor by 2 */
 158         gd->arch.plla_rate_hz /= (1 << ((mckr & 1 << 12) >> 12));
 159 #endif
 160         gd->arch.mck_rate_hz = at91_css_to_rate(mckr & AT91_PMC_MCKR_CSS_MASK);
 161         freq = gd->arch.mck_rate_hz;
 162
 163         freq /= (1 << ((mckr & AT91_PMC_MCKR_PRES_MASK) >> 2)); /* prescale */
 164 #if defined(CONFIG_AT91SAM9G20)
 165         /* mdiv ; (x >> 7) = ((x >> 8) * 2) */
 166         gd->arch.mck_rate_hz = (mckr & AT91_PMC_MCKR_MDIV_MASK) ?
 167                 freq / ((mckr & AT91_PMC_MCKR_MDIV_MASK) >> 7) : freq;
 168         if (mckr & AT91_PMC_MCKR_MDIV_MASK)
 169                 freq /= 2;                      /* processor clock division */
 170 #elif defined(CONFIG_AT91SAM9G45) || defined(CONFIG_AT91SAM9M10G45) \
 171                 || defined(CONFIG_AT91SAM9N12) || defined(CONFIG_AT91SAM9X5)
 172         /* mdiv <==> divisor
 173          *  0   <==>   1
 174          *  1   <==>   2
 175          *  2   <==>   4
 176          *  3   <==>   3
 177          */
 178         gd->arch.mck_rate_hz = (mckr & AT91_PMC_MCKR_MDIV_MASK) ==
 179                 (AT91_PMC_MCKR_MDIV_2 | AT91_PMC_MCKR_MDIV_4)
 180                 ? freq / 3
 181                 : freq / (1 << ((mckr & AT91_PMC_MCKR_MDIV_MASK) >> 8));
 182 #else
 183         gd->arch.mck_rate_hz = freq /
 184                         (1 << ((mckr & AT91_PMC_MCKR_MDIV_MASK) >> 8));
 185 #endif
 186         gd->arch.cpu_clk_rate_hz = freq;
 187
 188         return 0;
 189 }