LXR linux/arch/arm/mach-imx/cpu-imx27.c

   1/*
   2 * Copyright 2007 Freescale Semiconductor, Inc. All Rights Reserved.
   3 * Copyright 2008 Juergen Beisert, kernel@pengutronix.de
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of the GNU General Public License
   7 * as published by the Free Software Foundation; either version 2
   8 * of the License, or (at your option) any later version.
   9 * This program is distributed in the hope that it will be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write to the Free Software
  16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  17 * MA 02110-1301, USA.
  18 */
  19
  20/*
  21 * i.MX27 specific CPU detection code
  22 */
  23
  24#include <linux/io.h>
  25#include <linux/module.h>
  26
  27#include "hardware.h"
  28
  29static int mx27_cpu_rev = -1;
  30static int mx27_cpu_partnumber;
  31
  32#define SYS_CHIP_ID             0x00    /* The offset of CHIP ID register */
  33
  34static int mx27_read_cpu_rev(void)
  35{
  36        u32 val;
  37        /*
  38         * now we have access to the IO registers. As we need
  39         * the silicon revision very early we read it here to
  40         * avoid any further hooks
  41        */
  42        val = imx_readl(MX27_IO_ADDRESS(MX27_SYSCTRL_BASE_ADDR + SYS_CHIP_ID));
  43
  44        mx27_cpu_partnumber = (int)((val >> 12) & 0xFFFF);
  45
  46        switch (val >> 28) {
  47        case 0:
  48                return IMX_CHIP_REVISION_1_0;
  49        case 1:
  50                return IMX_CHIP_REVISION_2_0;
  51        case 2:
  52                return IMX_CHIP_REVISION_2_1;
  53        default:
  54                return IMX_CHIP_REVISION_UNKNOWN;
  55        }
  56}
  57
  58/*
  59 * Returns:
  60 *      the silicon revision of the cpu
  61 *      -EINVAL - not a mx27
  62 */
  63int mx27_revision(void)
  64{
  65        if (mx27_cpu_rev == -1)
  66                mx27_cpu_rev = mx27_read_cpu_rev();
  67
  68        if (mx27_cpu_partnumber != 0x8821)
  69                return -EINVAL;
  70
  71        return mx27_cpu_rev;
  72}
  73EXPORT_SYMBOL(mx27_revision);
  74