1 /* 2 * Copyright 2007 Freescale Semiconductor, Inc. All Rights Reserved. 3 * Copyright 2008 Juergen Beisert, kernel@pengutronix.de 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU General Public License 7 * as published by the Free Software Foundation; either version 2 8 * of the License, or (at your option) any later version. 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, write to the Free Software 16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, 17 * MA 02110-1301, USA. 18 */ 19 20 /* 21 * i.MX27 specific CPU detection code 22 */ 23 24 #include <linux/io.h> 25 #include <linux/module.h> 26 27 #include "hardware.h" 28 29 static int mx27_cpu_rev = -1; 30 static int mx27_cpu_partnumber; 31 32 #define SYS_CHIP_ID 0x00 /* The offset of CHIP ID register */ 33 34 static int mx27_read_cpu_rev(void) 35 { 36 u32 val; 37 /* 38 * now we have access to the IO registers. As we need 39 * the silicon revision very early we read it here to 40 * avoid any further hooks 41 */ 42 val = imx_readl(MX27_IO_ADDRESS(MX27_SYSCTRL_BASE_ADDR + SYS_CHIP_ID)); 43 44 mx27_cpu_partnumber = (int)((val >> 12) & 0xFFFF); 45 46 switch (val >> 28) { 47 case 0: 48 return IMX_CHIP_REVISION_1_0; 49 case 1: 50 return IMX_CHIP_REVISION_2_0; 51 case 2: 52 return IMX_CHIP_REVISION_2_1; 53 default: 54 return IMX_CHIP_REVISION_UNKNOWN; 55 } 56 } 57 58 /* 59 * Returns: 60 * the silicon revision of the cpu 61 * -EINVAL - not a mx27 62 */ 63 int mx27_revision(void) 64 { 65 if (mx27_cpu_rev == -1) 66 mx27_cpu_rev = mx27_read_cpu_rev(); 67 68 if (mx27_cpu_partnumber != 0x8821) 69 return -EINVAL; 70 71 return mx27_cpu_rev; 72 } 73 EXPORT_SYMBOL(mx27_revision); 74