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
 22struct us3_freq_percpu_info {
 23	struct cpufreq_frequency_table table[4];
 24};
 25
 26/* Indexed by cpu number. */
 27static 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
 37static 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
 47static void update_safari_cfg(void *arg)
 48{
 49	unsigned long reg, *new_bits = arg;
 50
 51	read_safari_cfg(&reg);
 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
 62static 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
 84static unsigned int us3_freq_get(unsigned int cpu)
 85{
 86	unsigned long reg;
 87
 88	if (smp_call_function_single(cpu, read_safari_cfg, &reg, 1))
 89		return 0;
 90	return get_current_freq(cpu, reg);
 91}
 92
 93static 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
120static 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
143static int us3_freq_cpu_exit(struct cpufreq_policy *policy)
144{
145	us3_freq_target(policy, 0);
146	return 0;
147}
148
149static 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
158static 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
190static void __exit us3_freq_exit(void)
191{
192	cpufreq_unregister_driver(&cpufreq_us3_driver);
193	kfree(us3_freq_table);
194}
195
196MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
197MODULE_DESCRIPTION("cpufreq driver for UltraSPARC-III");
198MODULE_LICENSE("GPL");
199
200module_init(us3_freq_init);
201module_exit(us3_freq_exit);