1 /* 2 * SH-Mobile Timer 3 * 4 * Copyright (C) 2010 Magnus Damm 5 * Copyright (C) 2002 - 2009 Paul Mundt 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/platform_device.h> 22 #include <linux/clocksource.h> 23 #include <linux/delay.h> 24 #include <linux/of_address.h> 25 26 static void __init shmobile_setup_delay_hz(unsigned int max_cpu_core_hz, 27 unsigned int mult, unsigned int div) 28 { 29 /* calculate a worst-case loops-per-jiffy value 30 * based on maximum cpu core hz setting and the 31 * __delay() implementation in arch/arm/lib/delay.S 32 * 33 * this will result in a longer delay than expected 34 * when the cpu core runs on lower frequencies. 35 */ 36 37 unsigned int value = HZ * div / mult; 38 39 if (!preset_lpj) 40 preset_lpj = max_cpu_core_hz / value; 41 } 42 43 void __init shmobile_init_delay(void) 44 { 45 struct device_node *np, *cpus; 46 bool is_a7_a8_a9 = false; 47 bool is_a15 = false; 48 u32 max_freq = 0; 49 50 cpus = of_find_node_by_path("/cpus"); 51 if (!cpus) 52 return; 53 54 for_each_child_of_node(cpus, np) { 55 u32 freq; 56 57 if (!of_property_read_u32(np, "clock-frequency", &freq)) 58 max_freq = max(max_freq, freq); 59 60 if (of_device_is_compatible(np, "arm,cortex-a7") || 61 of_device_is_compatible(np, "arm,cortex-a8") || 62 of_device_is_compatible(np, "arm,cortex-a9")) 63 is_a7_a8_a9 = true; 64 else if (of_device_is_compatible(np, "arm,cortex-a15")) 65 is_a15 = true; 66 } 67 68 of_node_put(cpus); 69 70 if (!max_freq) 71 return; 72 73 if (is_a7_a8_a9) 74 shmobile_setup_delay_hz(max_freq, 1, 3); 75 else if (is_a15 && !IS_ENABLED(CONFIG_ARM_ARCH_TIMER)) 76 shmobile_setup_delay_hz(max_freq, 2, 4); 77 } 78 79 static void __init shmobile_late_time_init(void) 80 { 81 /* 82 * Make sure all compiled-in early timers register themselves. 83 * 84 * Run probe() for two "earlytimer" devices, these will be the 85 * clockevents and clocksource devices respectively. In the event 86 * that only a clockevents device is available, we -ENODEV on the 87 * clocksource and the jiffies clocksource is used transparently 88 * instead. No error handling is necessary here. 89 */ 90 early_platform_driver_register_all("earlytimer"); 91 early_platform_driver_probe("earlytimer", 2, 0); 92 } 93 94 void __init shmobile_earlytimer_init(void) 95 { 96 late_time_init = shmobile_late_time_init; 97 } 98 99