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