arch/arm/cpu/armv7/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  * Copyright (C) 2013 Bo Shen <voice.shen@atmel.com>
   8  *
   9  * SPDX-License-Identifier:     GPL-2.0+
  10  */
  11
  12 #include <common.h>
  13 #include <asm/io.h>
  14 #include <asm/arch/hardware.h>
  15 #include <asm/arch/at91_pmc.h>
  16 #include <asm/arch/clk.h>
  17
  18 #if !defined(CONFIG_AT91FAMILY)
  19 # error You need to define CONFIG_AT91FAMILY in your board config!
  20 #endif
  21
  22 DECLARE_GLOBAL_DATA_PTR;
  23
  24 static unsigned long at91_css_to_rate(unsigned long css)
  25 {
  26         switch (css) {
  27         case AT91_PMC_MCKR_CSS_SLOW:
  28                 return CONFIG_SYS_AT91_SLOW_CLOCK;
  29         case AT91_PMC_MCKR_CSS_MAIN:
  30                 return gd->arch.main_clk_rate_hz;
  31         case AT91_PMC_MCKR_CSS_PLLA:
  32                 return gd->arch.plla_rate_hz;
  33         }
  34
  35         return 0;
  36 }
  37
  38 static u32 at91_pll_rate(u32 freq, u32 reg)
  39 {
  40         unsigned mul, div;
  41
  42         div = reg & 0xff;
  43         mul = (reg >> 18) & 0x7f;
  44         if (div && mul) {
  45                 freq /= div;
  46                 freq *= mul + 1;
  47         } else {
  48                 freq = 0;
  49         }
  50
  51         return freq;
  52 }
  53
  54 int at91_clock_init(unsigned long main_clock)
  55 {
  56         unsigned freq, mckr;
  57         struct at91_pmc *pmc = (struct at91_pmc *)ATMEL_BASE_PMC;
  58 #ifndef CONFIG_SYS_AT91_MAIN_CLOCK
  59         unsigned tmp;
  60         /*
  61          * When the bootloader initialized the main oscillator correctly,
  62          * there's no problem using the cycle counter.  But if it didn't,
  63          * or when using oscillator bypass mode, we must be told the speed
  64          * of the main clock.
  65          */
  66         if (!main_clock) {
  67                 do {
  68                         tmp = readl(&pmc->mcfr);
  69                 } while (!(tmp & AT91_PMC_MCFR_MAINRDY));
  70                 tmp &= AT91_PMC_MCFR_MAINF_MASK;
  71                 main_clock = tmp * (CONFIG_SYS_AT91_SLOW_CLOCK / 16);
  72         }
  73 #endif
  74         gd->arch.main_clk_rate_hz = main_clock;
  75
  76         /* report if PLLA is more than mildly overclocked */
  77         gd->arch.plla_rate_hz = at91_pll_rate(main_clock, readl(&pmc->pllar));
  78
  79         /*
  80          * MCK and CPU derive from one of those primary clocks.
  81          * For now, assume this parentage won't change.
  82          */
  83         mckr = readl(&pmc->mckr);
  84
  85         /* plla divisor by 2 */
  86         if (mckr & (1 << 12))
  87                 gd->arch.plla_rate_hz >>= 1;
  88
  89         gd->arch.mck_rate_hz = at91_css_to_rate(mckr & AT91_PMC_MCKR_CSS_MASK);
  90         freq = gd->arch.mck_rate_hz;
  91
  92         /* prescale */
  93         freq >>= mckr & AT91_PMC_MCKR_PRES_MASK;
  94
  95         switch (mckr & AT91_PMC_MCKR_MDIV_MASK) {
  96         case AT91_PMC_MCKR_MDIV_2:
  97                 gd->arch.mck_rate_hz = freq / 2;
  98                 break;
  99         case AT91_PMC_MCKR_MDIV_3:
 100                 gd->arch.mck_rate_hz = freq / 3;
 101                 break;
 102         case AT91_PMC_MCKR_MDIV_4:
 103                 gd->arch.mck_rate_hz = freq / 4;
 104                 break;
 105         default:
 106                 break;
 107         }
 108
 109         gd->arch.cpu_clk_rate_hz = freq;
 110
 111         return 0;
 112 }
 113
 114 void at91_periph_clk_enable(int id)
 115 {
 116         struct at91_pmc *pmc = (struct at91_pmc *)ATMEL_BASE_PMC;
 117
 118         if (id > 31)
 119                 writel(1 << (id - 32), &pmc->pcer1);
 120         else
 121                 writel(1 << id, &pmc->pcer);
 122 }