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