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 
mx27_read_cpu_rev(void)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  */
mx27_revision(void)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);
69