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 <mach/hardware.h> 28 29 static int cpu_silicon_rev = -1; 30 static int cpu_partnumber; 31 32 #define SYS_CHIP_ID 0x00 /* The offset of CHIP ID register */ 33 34 static void query_silicon_parameter(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 = __raw_readl(MX27_IO_ADDRESS(MX27_SYSCTRL_BASE_ADDR 43 + SYS_CHIP_ID)); 44 45 cpu_silicon_rev = (int)(val >> 28); 46 cpu_partnumber = (int)((val >> 12) & 0xFFFF); 47 } 48 49 /* 50 * Returns: 51 * the silicon revision of the cpu 52 * -EINVAL - not a mx27 53 */ 54 int mx27_revision(void) 55 { 56 if (cpu_silicon_rev == -1) 57 query_silicon_parameter(); 58 59 if (cpu_partnumber != 0x8821) 60 return -EINVAL; 61 62 return cpu_silicon_rev; 63 } 64 EXPORT_SYMBOL(mx27_revision); 65