1 /* 2 * R-Car Generation 2 support 3 * 4 * Copyright (C) 2013 Renesas Solutions Corp. 5 * Copyright (C) 2013 Magnus Damm 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License as published by 9 * the Free Software Foundation; version 2 of the License. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 19 */ 20 21 #include <linux/clocksource.h> 22 #include <linux/io.h> 23 #include <linux/kernel.h> 24 #include <mach/common.h> 25 #include <mach/rcar-gen2.h> 26 #include <asm/mach/arch.h> 27 28 #define MODEMR 0xe6160060 29 30 u32 __init rcar_gen2_read_mode_pins(void) 31 { 32 void __iomem *modemr = ioremap_nocache(MODEMR, 4); 33 u32 mode; 34 35 BUG_ON(!modemr); 36 mode = ioread32(modemr); 37 iounmap(modemr); 38 39 return mode; 40 } 41 42 #define CNTCR 0 43 #define CNTFID0 0x20 44 45 void __init rcar_gen2_timer_init(void) 46 { 47 #ifdef CONFIG_ARM_ARCH_TIMER 48 u32 mode = rcar_gen2_read_mode_pins(); 49 void __iomem *base; 50 int extal_mhz = 0; 51 u32 freq; 52 53 /* At Linux boot time the r8a7790 arch timer comes up 54 * with the counter disabled. Moreover, it may also report 55 * a potentially incorrect fixed 13 MHz frequency. To be 56 * correct these registers need to be updated to use the 57 * frequency EXTAL / 2 which can be determined by the MD pins. 58 */ 59 60 switch (mode & (MD(14) | MD(13))) { 61 case 0: 62 extal_mhz = 15; 63 break; 64 case MD(13): 65 extal_mhz = 20; 66 break; 67 case MD(14): 68 extal_mhz = 26; 69 break; 70 case MD(13) | MD(14): 71 extal_mhz = 30; 72 break; 73 } 74 75 /* The arch timer frequency equals EXTAL / 2 */ 76 freq = extal_mhz * (1000000 / 2); 77 78 /* Remap "armgcnt address map" space */ 79 base = ioremap(0xe6080000, PAGE_SIZE); 80 81 /* 82 * Update the timer if it is either not running, or is not at the 83 * right frequency. The timer is only configurable in secure mode 84 * so this avoids an abort if the loader started the timer and 85 * entered the kernel in non-secure mode. 86 */ 87 88 if ((ioread32(base + CNTCR) & 1) == 0 || 89 ioread32(base + CNTFID0) != freq) { 90 /* Update registers with correct frequency */ 91 iowrite32(freq, base + CNTFID0); 92 asm volatile("mcr p15, 0, %0, c14, c0, 0" : : "r" (freq)); 93 94 /* make sure arch timer is started by setting bit 0 of CNTCR */ 95 iowrite32(1, base + CNTCR); 96 } 97 98 iounmap(base); 99 #endif /* CONFIG_ARM_ARCH_TIMER */ 100 101 clocksource_of_init(); 102 } 103