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
read_safari_cfg(void * arg)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
update_safari_cfg(void * arg)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
get_current_freq(unsigned int cpu,unsigned long safari_cfg)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
us3_freq_get(unsigned int cpu)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
us3_freq_target(struct cpufreq_policy * policy,unsigned int index)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
us3_freq_cpu_init(struct cpufreq_policy * policy)120 static int 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
us3_freq_cpu_exit(struct cpufreq_policy * policy)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
us3_freq_init(void)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
us3_freq_exit(void)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