sparc-us3-cpufreq.c (5063B)
1// SPDX-License-Identifier: GPL-2.0-only 2/* us3_cpufreq.c: UltraSPARC-III cpu frequency support 3 * 4 * Copyright (C) 2003 David S. Miller (davem@redhat.com) 5 * 6 * Many thanks to Dominik Brodowski for fixing up the cpufreq 7 * infrastructure in order to make this driver easier to implement. 8 */ 9 10#include <linux/kernel.h> 11#include <linux/module.h> 12#include <linux/sched.h> 13#include <linux/smp.h> 14#include <linux/cpufreq.h> 15#include <linux/threads.h> 16#include <linux/slab.h> 17#include <linux/init.h> 18 19#include <asm/head.h> 20#include <asm/timer.h> 21 22static struct cpufreq_driver *cpufreq_us3_driver; 23 24struct us3_freq_percpu_info { 25 struct cpufreq_frequency_table table[4]; 26}; 27 28/* Indexed by cpu number. */ 29static struct us3_freq_percpu_info *us3_freq_table; 30 31/* UltraSPARC-III has three dividers: 1, 2, and 32. These are controlled 32 * in the Safari config register. 33 */ 34#define SAFARI_CFG_DIV_1 0x0000000000000000UL 35#define SAFARI_CFG_DIV_2 0x0000000040000000UL 36#define SAFARI_CFG_DIV_32 0x0000000080000000UL 37#define SAFARI_CFG_DIV_MASK 0x00000000C0000000UL 38 39static void read_safari_cfg(void *arg) 40{ 41 unsigned long ret, *val = arg; 42 43 __asm__ __volatile__("ldxa [%%g0] %1, %0" 44 : "=&r" (ret) 45 : "i" (ASI_SAFARI_CONFIG)); 46 *val = ret; 47} 48 49static void update_safari_cfg(void *arg) 50{ 51 unsigned long reg, *new_bits = arg; 52 53 read_safari_cfg(®); 54 reg &= ~SAFARI_CFG_DIV_MASK; 55 reg |= *new_bits; 56 57 __asm__ __volatile__("stxa %0, [%%g0] %1\n\t" 58 "membar #Sync" 59 : /* no outputs */ 60 : "r" (reg), "i" (ASI_SAFARI_CONFIG) 61 : "memory"); 62} 63 64static unsigned long get_current_freq(unsigned int cpu, unsigned long safari_cfg) 65{ 66 unsigned long clock_tick = sparc64_get_clock_tick(cpu) / 1000; 67 unsigned long ret; 68 69 switch (safari_cfg & SAFARI_CFG_DIV_MASK) { 70 case SAFARI_CFG_DIV_1: 71 ret = clock_tick / 1; 72 break; 73 case SAFARI_CFG_DIV_2: 74 ret = clock_tick / 2; 75 break; 76 case SAFARI_CFG_DIV_32: 77 ret = clock_tick / 32; 78 break; 79 default: 80 BUG(); 81 } 82 83 return ret; 84} 85 86static unsigned int us3_freq_get(unsigned int cpu) 87{ 88 unsigned long reg; 89 90 if (smp_call_function_single(cpu, read_safari_cfg, ®, 1)) 91 return 0; 92 return get_current_freq(cpu, reg); 93} 94 95static int us3_freq_target(struct cpufreq_policy *policy, unsigned int index) 96{ 97 unsigned int cpu = policy->cpu; 98 unsigned long new_bits, new_freq; 99 100 new_freq = sparc64_get_clock_tick(cpu) / 1000; 101 switch (index) { 102 case 0: 103 new_bits = SAFARI_CFG_DIV_1; 104 new_freq /= 1; 105 break; 106 case 1: 107 new_bits = SAFARI_CFG_DIV_2; 108 new_freq /= 2; 109 break; 110 case 2: 111 new_bits = SAFARI_CFG_DIV_32; 112 new_freq /= 32; 113 break; 114 115 default: 116 BUG(); 117 } 118 119 return smp_call_function_single(cpu, update_safari_cfg, &new_bits, 1); 120} 121 122static int __init us3_freq_cpu_init(struct cpufreq_policy *policy) 123{ 124 unsigned int cpu = policy->cpu; 125 unsigned long clock_tick = sparc64_get_clock_tick(cpu) / 1000; 126 struct cpufreq_frequency_table *table = 127 &us3_freq_table[cpu].table[0]; 128 129 table[0].driver_data = 0; 130 table[0].frequency = clock_tick / 1; 131 table[1].driver_data = 1; 132 table[1].frequency = clock_tick / 2; 133 table[2].driver_data = 2; 134 table[2].frequency = clock_tick / 32; 135 table[3].driver_data = 0; 136 table[3].frequency = CPUFREQ_TABLE_END; 137 138 policy->cpuinfo.transition_latency = 0; 139 policy->cur = clock_tick; 140 policy->freq_table = table; 141 142 return 0; 143} 144 145static int us3_freq_cpu_exit(struct cpufreq_policy *policy) 146{ 147 if (cpufreq_us3_driver) 148 us3_freq_target(policy, 0); 149 150 return 0; 151} 152 153static int __init us3_freq_init(void) 154{ 155 unsigned long manuf, impl, ver; 156 int ret; 157 158 if (tlb_type != cheetah && tlb_type != cheetah_plus) 159 return -ENODEV; 160 161 __asm__("rdpr %%ver, %0" : "=r" (ver)); 162 manuf = ((ver >> 48) & 0xffff); 163 impl = ((ver >> 32) & 0xffff); 164 165 if (manuf == CHEETAH_MANUF && 166 (impl == CHEETAH_IMPL || 167 impl == CHEETAH_PLUS_IMPL || 168 impl == JAGUAR_IMPL || 169 impl == PANTHER_IMPL)) { 170 struct cpufreq_driver *driver; 171 172 ret = -ENOMEM; 173 driver = kzalloc(sizeof(*driver), GFP_KERNEL); 174 if (!driver) 175 goto err_out; 176 177 us3_freq_table = kzalloc((NR_CPUS * sizeof(*us3_freq_table)), 178 GFP_KERNEL); 179 if (!us3_freq_table) 180 goto err_out; 181 182 driver->init = us3_freq_cpu_init; 183 driver->verify = cpufreq_generic_frequency_table_verify; 184 driver->target_index = us3_freq_target; 185 driver->get = us3_freq_get; 186 driver->exit = us3_freq_cpu_exit; 187 strcpy(driver->name, "UltraSPARC-III"); 188 189 cpufreq_us3_driver = driver; 190 ret = cpufreq_register_driver(driver); 191 if (ret) 192 goto err_out; 193 194 return 0; 195 196err_out: 197 if (driver) { 198 kfree(driver); 199 cpufreq_us3_driver = NULL; 200 } 201 kfree(us3_freq_table); 202 us3_freq_table = NULL; 203 return ret; 204 } 205 206 return -ENODEV; 207} 208 209static void __exit us3_freq_exit(void) 210{ 211 if (cpufreq_us3_driver) { 212 cpufreq_unregister_driver(cpufreq_us3_driver); 213 kfree(cpufreq_us3_driver); 214 cpufreq_us3_driver = NULL; 215 kfree(us3_freq_table); 216 us3_freq_table = NULL; 217 } 218} 219 220MODULE_AUTHOR("David S. Miller <davem@redhat.com>"); 221MODULE_DESCRIPTION("cpufreq driver for UltraSPARC-III"); 222MODULE_LICENSE("GPL"); 223 224module_init(us3_freq_init); 225module_exit(us3_freq_exit);