1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Copyright 2007 Freescale Semiconductor, Inc. All Rights Reserved.
4 * Copyright 2008 Juergen Beisert, kernel@pengutronix.de
8 * i.MX27 specific CPU detection code
12 #include <linux/of_address.h>
13 #include <linux/module.h>
17 static int mx27_cpu_rev = -1;
18 static int mx27_cpu_partnumber;
20 #define SYS_CHIP_ID 0x00 /* The offset of CHIP ID register */
21 #define SYSCTRL_OFFSET 0x800 /* Offset from CCM base address */
23 static int mx27_read_cpu_rev(void)
25 void __iomem *ccm_base;
26 struct device_node *np;
29 np = of_find_compatible_node(NULL, NULL, "fsl,imx27-ccm");
30 ccm_base = of_iomap(np, 0);
34 * now we have access to the IO registers. As we need
35 * the silicon revision very early we read it here to
36 * avoid any further hooks
38 val = imx_readl(ccm_base + SYSCTRL_OFFSET + SYS_CHIP_ID);
40 mx27_cpu_partnumber = (int)((val >> 12) & 0xFFFF);
44 return IMX_CHIP_REVISION_1_0;
46 return IMX_CHIP_REVISION_2_0;
48 return IMX_CHIP_REVISION_2_1;
50 return IMX_CHIP_REVISION_UNKNOWN;
56 * the silicon revision of the cpu
57 * -EINVAL - not a mx27
59 int mx27_revision(void)
61 if (mx27_cpu_rev == -1)
62 mx27_cpu_rev = mx27_read_cpu_rev();
64 if (mx27_cpu_partnumber != 0x8821)
69 EXPORT_SYMBOL(mx27_revision);