arch/arm/mach-tegra/tegra20/cpu.c

   1 /*
   2  * Copyright (c) 2010-2012, NVIDIA CORPORATION.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms and conditions of the GNU General Public License,
   6  * version 2, as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15  */
  16
  17 #include <common.h>
  18 #include <asm/io.h>
  19 #include <asm/arch/tegra.h>
  20 #include <asm/arch-tegra/pmc.h>
  21 #include "../cpu.h"
  22
  23 static void enable_cpu_power_rail(void)
  24 {
  25         struct pmc_ctlr *pmc = (struct pmc_ctlr *)NV_PA_PMC_BASE;
  26         u32 reg;
  27
  28         reg = readl(&pmc->pmc_cntrl);
  29         reg |= CPUPWRREQ_OE;
  30         writel(reg, &pmc->pmc_cntrl);
  31
  32         /*
  33          * The TI PMU65861C needs a 3.75ms delay between enabling
  34          * the power rail and enabling the CPU clock.  This delay
  35          * between SM1EN and SM1 is for switching time + the ramp
  36          * up of the voltage to the CPU (VDD_CPU from PMU).
  37          */
  38         udelay(3750);
  39 }
  40
  41 void start_cpu(u32 reset_vector)
  42 {
  43         /* Enable VDD_CPU */
  44         enable_cpu_power_rail();
  45
  46         /* Hold the CPUs in reset */
  47         reset_A9_cpu(1);
  48
  49         /* Disable the CPU clock */
  50         enable_cpu_clock(0);
  51
  52         /* Enable CoreSight */
  53         clock_enable_coresight(1);
  54
  55         /*
  56          * Set the entry point for CPU execution from reset,
  57          *  if it's a non-zero value.
  58          */
  59         if (reset_vector)
  60                 writel(reset_vector, EXCEP_VECTOR_CPU_RESET_VECTOR);
  61
  62         /* Enable the CPU clock */
  63         enable_cpu_clock(1);
  64
  65         /* If the CPU doesn't already have power, power it up */
  66         powerup_cpu();
  67
  68         /* Take the CPU out of reset */
  69         reset_A9_cpu(0);
  70 }