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 #include <linux/platform_device.h> 17 #include <linux/clocksource.h> 18 #include <linux/delay.h> 19 #include <linux/of_address.h> 20 21 #include "common.h" 22 23 static void __init shmobile_setup_delay_hz(unsigned int max_cpu_core_hz, 24 unsigned int mult, unsigned int div) 25 { 26 /* calculate a worst-case loops-per-jiffy value 27 * based on maximum cpu core hz setting and the 28 * __delay() implementation in arch/arm/lib/delay.S 29 * 30 * this will result in a longer delay than expected 31 * when the cpu core runs on lower frequencies. 32 */ 33 34 unsigned int value = HZ * div / mult; 35 36 if (!preset_lpj) 37 preset_lpj = max_cpu_core_hz / value; 38 } 39 40 void __init shmobile_init_delay(void) 41 { 42 struct device_node *np, *cpus; 43 bool is_a7_a8_a9 = false; 44 bool is_a15 = false; 45 bool has_arch_timer = false; 46 u32 max_freq = 0; 47 48 cpus = of_find_node_by_path("/cpus"); 49 if (!cpus) 50 return; 51 52 for_each_child_of_node(cpus, np) { 53 u32 freq; 54 55 if (!of_property_read_u32(np, "clock-frequency", &freq)) 56 max_freq = max(max_freq, freq); 57 58 if (of_device_is_compatible(np, "arm,cortex-a8") || 59 of_device_is_compatible(np, "arm,cortex-a9")) { 60 is_a7_a8_a9 = true; 61 } else if (of_device_is_compatible(np, "arm,cortex-a7")) { 62 is_a7_a8_a9 = true; 63 has_arch_timer = true; 64 } else if (of_device_is_compatible(np, "arm,cortex-a15")) { 65 is_a15 = true; 66 has_arch_timer = true; 67 } 68 } 69 70 of_node_put(cpus); 71 72 if (!max_freq) 73 return; 74 75 if (!has_arch_timer || !IS_ENABLED(CONFIG_ARM_ARCH_TIMER)) { 76 if (is_a7_a8_a9) 77 shmobile_setup_delay_hz(max_freq, 1, 3); 78 else if (is_a15) 79 shmobile_setup_delay_hz(max_freq, 2, 4); 80 } 81 } 82