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 static struct cpufreq_driver *cpufreq_us3_driver;
23
24 struct us3_freq_percpu_info {
25 struct cpufreq_frequency_table table[4];
26 };
27
28 /* Indexed by cpu number. */
29 static 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
read_safari_cfg(void * arg)39 static 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
update_safari_cfg(void * arg)49 static 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
get_current_freq(unsigned int cpu,unsigned long safari_cfg)64 static 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
us3_freq_get(unsigned int cpu)86 static 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
us3_freq_target(struct cpufreq_policy * policy,unsigned int index)95 static 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
us3_freq_cpu_init(struct cpufreq_policy * policy)122 static 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
us3_freq_cpu_exit(struct cpufreq_policy * policy)145 static 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
us3_freq_init(void)153 static 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
196 err_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
us3_freq_exit(void)209 static 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
220 MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
221 MODULE_DESCRIPTION("cpufreq driver for UltraSPARC-III");
222 MODULE_LICENSE("GPL");
223
224 module_init(us3_freq_init);
225 module_exit(us3_freq_exit);
226