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); 61