GNU Linux-libre 5.19-rc6-gnu
[releases.git] / drivers / cpufreq / sparc-us3-cpufreq.c
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
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
49 static void update_safari_cfg(void *arg)
50 {
51         unsigned long reg, *new_bits = arg;
52
53         read_safari_cfg(&reg);
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
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
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, &reg, 1))
91                 return 0;
92         return get_current_freq(cpu, reg);
93 }
94
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
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
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
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
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);