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/of_address.h>
  13 #include <linux/module.h>
  14
  15 #include "hardware.h"
  16
  17 static int mx27_cpu_rev = -1;
  18 static int mx27_cpu_partnumber;
  19
  20 #define SYS_CHIP_ID             0x00    /* The offset of CHIP ID register */
  21 #define SYSCTRL_OFFSET          0x800   /* Offset from CCM base address */
  22
  23 static int mx27_read_cpu_rev(void)
  24 {
  25         void __iomem *ccm_base;
  26         struct device_node *np;
  27         u32 val;
  28
  29         np = of_find_compatible_node(NULL, NULL, "fsl,imx27-ccm");
  30         ccm_base = of_iomap(np, 0);
  31         BUG_ON(!ccm_base);
  32         /*
  33          * now we have access to the IO registers. As we need
  34          * the silicon revision very early we read it here to
  35          * avoid any further hooks
  36         */
  37         val = imx_readl(ccm_base + SYSCTRL_OFFSET + SYS_CHIP_ID);
  38
  39         mx27_cpu_partnumber = (int)((val >> 12) & 0xFFFF);
  40
  41         switch (val >> 28) {
  42         case 0:
  43                 return IMX_CHIP_REVISION_1_0;
  44         case 1:
  45                 return IMX_CHIP_REVISION_2_0;
  46         case 2:
  47                 return IMX_CHIP_REVISION_2_1;
  48         default:
  49                 return IMX_CHIP_REVISION_UNKNOWN;
  50         }
  51 }
  52
  53 /*
  54  * Returns:
  55  *      the silicon revision of the cpu
  56  *      -EINVAL - not a mx27
  57  */
  58 int mx27_revision(void)
  59 {
  60         if (mx27_cpu_rev == -1)
  61                 mx27_cpu_rev = mx27_read_cpu_rev();
  62
  63         if (mx27_cpu_partnumber != 0x8821)
  64                 return -EINVAL;
  65
  66         return mx27_cpu_rev;
  67 }
  68 EXPORT_SYMBOL(mx27_revision);