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
 22static struct cpufreq_driver *cpufreq_us3_driver;
 23
 24struct us3_freq_percpu_info {
 25	struct cpufreq_frequency_table table[4];
 26};
 27
 28/* Indexed by cpu number. */
 29static 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
 39static 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
 49static 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
 64static 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
 86static 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
 95static 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
122static 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
145static 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
153static 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
196err_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
209static 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
220MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
221MODULE_DESCRIPTION("cpufreq driver for UltraSPARC-III");
222MODULE_LICENSE("GPL");
223
224module_init(us3_freq_init);
225module_exit(us3_freq_exit);