1// SPDX-License-Identifier: GPL-2.0-only
2/* us2e_cpufreq.c: UltraSPARC-IIe 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/delay.h>
18#include <linux/init.h>
19
20#include <asm/asi.h>
21#include <asm/timer.h>
22
23struct us2e_freq_percpu_info {
24 struct cpufreq_frequency_table table[6];
25};
26
27/* Indexed by cpu number. */
28static struct us2e_freq_percpu_info *us2e_freq_table;
29
30#define HBIRD_MEM_CNTL0_ADDR 0x1fe0000f010UL
31#define HBIRD_ESTAR_MODE_ADDR 0x1fe0000f080UL
32
33/* UltraSPARC-IIe has five dividers: 1, 2, 4, 6, and 8. These are controlled
34 * in the ESTAR mode control register.
35 */
36#define ESTAR_MODE_DIV_1 0x0000000000000000UL
37#define ESTAR_MODE_DIV_2 0x0000000000000001UL
38#define ESTAR_MODE_DIV_4 0x0000000000000003UL
39#define ESTAR_MODE_DIV_6 0x0000000000000002UL
40#define ESTAR_MODE_DIV_8 0x0000000000000004UL
41#define ESTAR_MODE_DIV_MASK 0x0000000000000007UL
42
43#define MCTRL0_SREFRESH_ENAB 0x0000000000010000UL
44#define MCTRL0_REFR_COUNT_MASK 0x0000000000007f00UL
45#define MCTRL0_REFR_COUNT_SHIFT 8
46#define MCTRL0_REFR_INTERVAL 7800
47#define MCTRL0_REFR_CLKS_P_CNT 64
48
49static unsigned long read_hbreg(unsigned long addr)
50{
51 unsigned long ret;
52
53 __asm__ __volatile__("ldxa [%1] %2, %0"
54 : "=&r" (ret)
55 : "r" (addr), "i" (ASI_PHYS_BYPASS_EC_E));
56 return ret;
57}
58
59static void write_hbreg(unsigned long addr, unsigned long val)
60{
61 __asm__ __volatile__("stxa %0, [%1] %2\n\t"
62 "membar #Sync"
63 : /* no outputs */
64 : "r" (val), "r" (addr), "i" (ASI_PHYS_BYPASS_EC_E)
65 : "memory");
66 if (addr == HBIRD_ESTAR_MODE_ADDR) {
67 /* Need to wait 16 clock cycles for the PLL to lock. */
68 udelay(1);
69 }
70}
71
72static void self_refresh_ctl(int enable)
73{
74 unsigned long mctrl = read_hbreg(HBIRD_MEM_CNTL0_ADDR);
75
76 if (enable)
77 mctrl |= MCTRL0_SREFRESH_ENAB;
78 else
79 mctrl &= ~MCTRL0_SREFRESH_ENAB;
80 write_hbreg(HBIRD_MEM_CNTL0_ADDR, val: mctrl);
81 (void) read_hbreg(HBIRD_MEM_CNTL0_ADDR);
82}
83
84static void frob_mem_refresh(int cpu_slowing_down,
85 unsigned long clock_tick,
86 unsigned long old_divisor, unsigned long divisor)
87{
88 unsigned long old_refr_count, refr_count, mctrl;
89
90 refr_count = (clock_tick * MCTRL0_REFR_INTERVAL);
91 refr_count /= (MCTRL0_REFR_CLKS_P_CNT * divisor * 1000000000UL);
92
93 mctrl = read_hbreg(HBIRD_MEM_CNTL0_ADDR);
94 old_refr_count = (mctrl & MCTRL0_REFR_COUNT_MASK)
95 >> MCTRL0_REFR_COUNT_SHIFT;
96
97 mctrl &= ~MCTRL0_REFR_COUNT_MASK;
98 mctrl |= refr_count << MCTRL0_REFR_COUNT_SHIFT;
99 write_hbreg(HBIRD_MEM_CNTL0_ADDR, val: mctrl);
100 mctrl = read_hbreg(HBIRD_MEM_CNTL0_ADDR);
101
102 if (cpu_slowing_down && !(mctrl & MCTRL0_SREFRESH_ENAB)) {
103 unsigned long usecs;
104
105 /* We have to wait for both refresh counts (old
106 * and new) to go to zero.
107 */
108 usecs = (MCTRL0_REFR_CLKS_P_CNT *
109 (refr_count + old_refr_count) *
110 1000000UL *
111 old_divisor) / clock_tick;
112 udelay(usecs + 1UL);
113 }
114}
115
116static void us2e_transition(unsigned long estar, unsigned long new_bits,
117 unsigned long clock_tick,
118 unsigned long old_divisor, unsigned long divisor)
119{
120 estar &= ~ESTAR_MODE_DIV_MASK;
121
122 /* This is based upon the state transition diagram in the IIe manual. */
123 if (old_divisor == 2 && divisor == 1) {
124 self_refresh_ctl(enable: 0);
125 write_hbreg(HBIRD_ESTAR_MODE_ADDR, val: estar | new_bits);
126 frob_mem_refresh(cpu_slowing_down: 0, clock_tick, old_divisor, divisor);
127 } else if (old_divisor == 1 && divisor == 2) {
128 frob_mem_refresh(cpu_slowing_down: 1, clock_tick, old_divisor, divisor);
129 write_hbreg(HBIRD_ESTAR_MODE_ADDR, val: estar | new_bits);
130 self_refresh_ctl(enable: 1);
131 } else if (old_divisor == 1 && divisor > 2) {
132 us2e_transition(estar, ESTAR_MODE_DIV_2, clock_tick,
133 old_divisor: 1, divisor: 2);
134 us2e_transition(estar, new_bits, clock_tick,
135 old_divisor: 2, divisor);
136 } else if (old_divisor > 2 && divisor == 1) {
137 us2e_transition(estar, ESTAR_MODE_DIV_2, clock_tick,
138 old_divisor, divisor: 2);
139 us2e_transition(estar, new_bits, clock_tick,
140 old_divisor: 2, divisor);
141 } else if (old_divisor < divisor) {
142 frob_mem_refresh(cpu_slowing_down: 0, clock_tick, old_divisor, divisor);
143 write_hbreg(HBIRD_ESTAR_MODE_ADDR, val: estar | new_bits);
144 } else if (old_divisor > divisor) {
145 write_hbreg(HBIRD_ESTAR_MODE_ADDR, val: estar | new_bits);
146 frob_mem_refresh(cpu_slowing_down: 1, clock_tick, old_divisor, divisor);
147 } else {
148 BUG();
149 }
150}
151
152static unsigned long index_to_estar_mode(unsigned int index)
153{
154 switch (index) {
155 case 0:
156 return ESTAR_MODE_DIV_1;
157
158 case 1:
159 return ESTAR_MODE_DIV_2;
160
161 case 2:
162 return ESTAR_MODE_DIV_4;
163
164 case 3:
165 return ESTAR_MODE_DIV_6;
166
167 case 4:
168 return ESTAR_MODE_DIV_8;
169
170 default:
171 BUG();
172 }
173}
174
175static unsigned long index_to_divisor(unsigned int index)
176{
177 switch (index) {
178 case 0:
179 return 1;
180
181 case 1:
182 return 2;
183
184 case 2:
185 return 4;
186
187 case 3:
188 return 6;
189
190 case 4:
191 return 8;
192
193 default:
194 BUG();
195 }
196}
197
198static unsigned long estar_to_divisor(unsigned long estar)
199{
200 unsigned long ret;
201
202 switch (estar & ESTAR_MODE_DIV_MASK) {
203 case ESTAR_MODE_DIV_1:
204 ret = 1;
205 break;
206 case ESTAR_MODE_DIV_2:
207 ret = 2;
208 break;
209 case ESTAR_MODE_DIV_4:
210 ret = 4;
211 break;
212 case ESTAR_MODE_DIV_6:
213 ret = 6;
214 break;
215 case ESTAR_MODE_DIV_8:
216 ret = 8;
217 break;
218 default:
219 BUG();
220 }
221
222 return ret;
223}
224
225static void __us2e_freq_get(void *arg)
226{
227 unsigned long *estar = arg;
228
229 *estar = read_hbreg(HBIRD_ESTAR_MODE_ADDR);
230}
231
232static unsigned int us2e_freq_get(unsigned int cpu)
233{
234 unsigned long clock_tick, estar;
235
236 clock_tick = sparc64_get_clock_tick(cpu) / 1000;
237 if (smp_call_function_single(cpuid: cpu, func: __us2e_freq_get, info: &estar, wait: 1))
238 return 0;
239
240 return clock_tick / estar_to_divisor(estar);
241}
242
243static void __us2e_freq_target(void *arg)
244{
245 unsigned int cpu = smp_processor_id();
246 unsigned int *index = arg;
247 unsigned long new_bits, new_freq;
248 unsigned long clock_tick, divisor, old_divisor, estar;
249
250 new_freq = clock_tick = sparc64_get_clock_tick(cpu) / 1000;
251 new_bits = index_to_estar_mode(index: *index);
252 divisor = index_to_divisor(index: *index);
253 new_freq /= divisor;
254
255 estar = read_hbreg(HBIRD_ESTAR_MODE_ADDR);
256
257 old_divisor = estar_to_divisor(estar);
258
259 if (old_divisor != divisor) {
260 us2e_transition(estar, new_bits, clock_tick: clock_tick * 1000,
261 old_divisor, divisor);
262 }
263}
264
265static int us2e_freq_target(struct cpufreq_policy *policy, unsigned int index)
266{
267 unsigned int cpu = policy->cpu;
268
269 return smp_call_function_single(cpuid: cpu, func: __us2e_freq_target, info: &index, wait: 1);
270}
271
272static int us2e_freq_cpu_init(struct cpufreq_policy *policy)
273{
274 unsigned int cpu = policy->cpu;
275 unsigned long clock_tick = sparc64_get_clock_tick(cpu) / 1000;
276 struct cpufreq_frequency_table *table =
277 &us2e_freq_table[cpu].table[0];
278
279 table[0].driver_data = 0;
280 table[0].frequency = clock_tick / 1;
281 table[1].driver_data = 1;
282 table[1].frequency = clock_tick / 2;
283 table[2].driver_data = 2;
284 table[2].frequency = clock_tick / 4;
285 table[2].driver_data = 3;
286 table[2].frequency = clock_tick / 6;
287 table[2].driver_data = 4;
288 table[2].frequency = clock_tick / 8;
289 table[2].driver_data = 5;
290 table[3].frequency = CPUFREQ_TABLE_END;
291
292 policy->cpuinfo.transition_latency = 0;
293 policy->cur = clock_tick;
294 policy->freq_table = table;
295
296 return 0;
297}
298
299static int us2e_freq_cpu_exit(struct cpufreq_policy *policy)
300{
301 us2e_freq_target(policy, index: 0);
302 return 0;
303}
304
305static struct cpufreq_driver cpufreq_us2e_driver = {
306 .name = "UltraSPARC-IIe",
307 .init = us2e_freq_cpu_init,
308 .verify = cpufreq_generic_frequency_table_verify,
309 .target_index = us2e_freq_target,
310 .get = us2e_freq_get,
311 .exit = us2e_freq_cpu_exit,
312};
313
314static int __init us2e_freq_init(void)
315{
316 unsigned long manuf, impl, ver;
317 int ret;
318
319 if (tlb_type != spitfire)
320 return -ENODEV;
321
322 __asm__("rdpr %%ver, %0" : "=r" (ver));
323 manuf = ((ver >> 48) & 0xffff);
324 impl = ((ver >> 32) & 0xffff);
325
326 if (manuf == 0x17 && impl == 0x13) {
327 us2e_freq_table = kzalloc(NR_CPUS * sizeof(*us2e_freq_table),
328 GFP_KERNEL);
329 if (!us2e_freq_table)
330 return -ENOMEM;
331
332 ret = cpufreq_register_driver(driver_data: &cpufreq_us2e_driver);
333 if (ret)
334 kfree(objp: us2e_freq_table);
335
336 return ret;
337 }
338
339 return -ENODEV;
340}
341
342static void __exit us2e_freq_exit(void)
343{
344 cpufreq_unregister_driver(driver_data: &cpufreq_us2e_driver);
345 kfree(objp: us2e_freq_table);
346}
347
348MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
349MODULE_DESCRIPTION("cpufreq driver for UltraSPARC-IIe");
350MODULE_LICENSE("GPL");
351
352module_init(us2e_freq_init);
353module_exit(us2e_freq_exit);
354

source code of linux/drivers/cpufreq/sparc-us2e-cpufreq.c