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

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright 2007 Freescale Semiconductor, Inc. All Rights Reserved.
   4  * Copyright 2008 Juergen Beisert, kernel@pengutronix.de
   5  */
   6
   7 /*
   8  * i.MX27 specific CPU detection code
   9  */
  10
  11 #include <linux/io.h>
  12 #include <linux/module.h>
  13
  14 #include "hardware.h"
  15
  16 static int mx27_cpu_rev = -1;
  17 static int mx27_cpu_partnumber;
  18
  19 #define SYS_CHIP_ID             0x00    /* The offset of CHIP ID register */
  20
  21 static int mx27_read_cpu_rev(void)
  22 {
  23         u32 val;
  24         /*
  25          * now we have access to the IO registers. As we need
  26          * the silicon revision very early we read it here to
  27          * avoid any further hooks
  28         */
  29         val = imx_readl(MX27_IO_ADDRESS(MX27_SYSCTRL_BASE_ADDR + SYS_CHIP_ID));
  30
  31         mx27_cpu_partnumber = (int)((val >> 12) & 0xFFFF);
  32
  33         switch (val >> 28) {
  34         case 0:
  35                 return IMX_CHIP_REVISION_1_0;
  36         case 1:
  37                 return IMX_CHIP_REVISION_2_0;
  38         case 2:
  39                 return IMX_CHIP_REVISION_2_1;
  40         default:
  41                 return IMX_CHIP_REVISION_UNKNOWN;
  42         }
  43 }
  44
  45 /*
  46  * Returns:
  47  *      the silicon revision of the cpu
  48  *      -EINVAL - not a mx27
  49  */
  50 int mx27_revision(void)
  51 {
  52         if (mx27_cpu_rev == -1)
  53                 mx27_cpu_rev = mx27_read_cpu_rev();
  54
  55         if (mx27_cpu_partnumber != 0x8821)
  56                 return -EINVAL;
  57
  58         return mx27_cpu_rev;
  59 }
  60 EXPORT_SYMBOL(mx27_revision);