1/* us3_cpufreq.c: UltraSPARC-III cpu frequency support
2 *
3 * Copyright (C) 2003 David S. Miller (davem@redhat.com)
4 *
5 * Many thanks to Dominik Brodowski for fixing up the cpufreq
6 * infrastructure in order to make this driver easier to implement.
7 */
8
9#include <linux/kernel.h>
10#include <linux/module.h>
11#include <linux/sched.h>
12#include <linux/smp.h>
13#include <linux/cpufreq.h>
14#include <linux/threads.h>
15#include <linux/slab.h>
16#include <linux/init.h>
17
18#include <asm/head.h>
19#include <asm/timer.h>
20
21static struct cpufreq_driver *cpufreq_us3_driver;
22
23struct us3_freq_percpu_info {
24	struct cpufreq_frequency_table table[4];
25};
26
27/* Indexed by cpu number. */
28static struct us3_freq_percpu_info *us3_freq_table;
29
30/* UltraSPARC-III has three dividers: 1, 2, and 32.  These are controlled
31 * in the Safari config register.
32 */
33#define SAFARI_CFG_DIV_1	0x0000000000000000UL
34#define SAFARI_CFG_DIV_2	0x0000000040000000UL
35#define SAFARI_CFG_DIV_32	0x0000000080000000UL
36#define SAFARI_CFG_DIV_MASK	0x00000000C0000000UL
37
38static unsigned long read_safari_cfg(void)
39{
40	unsigned long ret;
41
42	__asm__ __volatile__("ldxa	[%%g0] %1, %0"
43			     : "=&r" (ret)
44			     : "i" (ASI_SAFARI_CONFIG));
45	return ret;
46}
47
48static void write_safari_cfg(unsigned long val)
49{
50	__asm__ __volatile__("stxa	%0, [%%g0] %1\n\t"
51			     "membar	#Sync"
52			     : /* no outputs */
53			     : "r" (val), "i" (ASI_SAFARI_CONFIG)
54			     : "memory");
55}
56
57static unsigned long get_current_freq(unsigned int cpu, unsigned long safari_cfg)
58{
59	unsigned long clock_tick = sparc64_get_clock_tick(cpu) / 1000;
60	unsigned long ret;
61
62	switch (safari_cfg & SAFARI_CFG_DIV_MASK) {
63	case SAFARI_CFG_DIV_1:
64		ret = clock_tick / 1;
65		break;
66	case SAFARI_CFG_DIV_2:
67		ret = clock_tick / 2;
68		break;
69	case SAFARI_CFG_DIV_32:
70		ret = clock_tick / 32;
71		break;
72	default:
73		BUG();
74	}
75
76	return ret;
77}
78
79static unsigned int us3_freq_get(unsigned int cpu)
80{
81	cpumask_t cpus_allowed;
82	unsigned long reg;
83	unsigned int ret;
84
85	cpumask_copy(&cpus_allowed, tsk_cpus_allowed(current));
86	set_cpus_allowed_ptr(current, cpumask_of(cpu));
87
88	reg = read_safari_cfg();
89	ret = get_current_freq(cpu, reg);
90
91	set_cpus_allowed_ptr(current, &cpus_allowed);
92
93	return ret;
94}
95
96static int us3_freq_target(struct cpufreq_policy *policy, unsigned int index)
97{
98	unsigned int cpu = policy->cpu;
99	unsigned long new_bits, new_freq, reg;
100	cpumask_t cpus_allowed;
101
102	cpumask_copy(&cpus_allowed, tsk_cpus_allowed(current));
103	set_cpus_allowed_ptr(current, cpumask_of(cpu));
104
105	new_freq = sparc64_get_clock_tick(cpu) / 1000;
106	switch (index) {
107	case 0:
108		new_bits = SAFARI_CFG_DIV_1;
109		new_freq /= 1;
110		break;
111	case 1:
112		new_bits = SAFARI_CFG_DIV_2;
113		new_freq /= 2;
114		break;
115	case 2:
116		new_bits = SAFARI_CFG_DIV_32;
117		new_freq /= 32;
118		break;
119
120	default:
121		BUG();
122	}
123
124	reg = read_safari_cfg();
125
126	reg &= ~SAFARI_CFG_DIV_MASK;
127	reg |= new_bits;
128	write_safari_cfg(reg);
129
130	set_cpus_allowed_ptr(current, &cpus_allowed);
131
132	return 0;
133}
134
135static int __init us3_freq_cpu_init(struct cpufreq_policy *policy)
136{
137	unsigned int cpu = policy->cpu;
138	unsigned long clock_tick = sparc64_get_clock_tick(cpu) / 1000;
139	struct cpufreq_frequency_table *table =
140		&us3_freq_table[cpu].table[0];
141
142	table[0].driver_data = 0;
143	table[0].frequency = clock_tick / 1;
144	table[1].driver_data = 1;
145	table[1].frequency = clock_tick / 2;
146	table[2].driver_data = 2;
147	table[2].frequency = clock_tick / 32;
148	table[3].driver_data = 0;
149	table[3].frequency = CPUFREQ_TABLE_END;
150
151	policy->cpuinfo.transition_latency = 0;
152	policy->cur = clock_tick;
153
154	return cpufreq_table_validate_and_show(policy, table);
155}
156
157static int us3_freq_cpu_exit(struct cpufreq_policy *policy)
158{
159	if (cpufreq_us3_driver)
160		us3_freq_target(policy, 0);
161
162	return 0;
163}
164
165static int __init us3_freq_init(void)
166{
167	unsigned long manuf, impl, ver;
168	int ret;
169
170	if (tlb_type != cheetah && tlb_type != cheetah_plus)
171		return -ENODEV;
172
173	__asm__("rdpr %%ver, %0" : "=r" (ver));
174	manuf = ((ver >> 48) & 0xffff);
175	impl  = ((ver >> 32) & 0xffff);
176
177	if (manuf == CHEETAH_MANUF &&
178	    (impl == CHEETAH_IMPL ||
179	     impl == CHEETAH_PLUS_IMPL ||
180	     impl == JAGUAR_IMPL ||
181	     impl == PANTHER_IMPL)) {
182		struct cpufreq_driver *driver;
183
184		ret = -ENOMEM;
185		driver = kzalloc(sizeof(*driver), GFP_KERNEL);
186		if (!driver)
187			goto err_out;
188
189		us3_freq_table = kzalloc((NR_CPUS * sizeof(*us3_freq_table)),
190			GFP_KERNEL);
191		if (!us3_freq_table)
192			goto err_out;
193
194		driver->init = us3_freq_cpu_init;
195		driver->verify = cpufreq_generic_frequency_table_verify;
196		driver->target_index = us3_freq_target;
197		driver->get = us3_freq_get;
198		driver->exit = us3_freq_cpu_exit;
199		strcpy(driver->name, "UltraSPARC-III");
200
201		cpufreq_us3_driver = driver;
202		ret = cpufreq_register_driver(driver);
203		if (ret)
204			goto err_out;
205
206		return 0;
207
208err_out:
209		if (driver) {
210			kfree(driver);
211			cpufreq_us3_driver = NULL;
212		}
213		kfree(us3_freq_table);
214		us3_freq_table = NULL;
215		return ret;
216	}
217
218	return -ENODEV;
219}
220
221static void __exit us3_freq_exit(void)
222{
223	if (cpufreq_us3_driver) {
224		cpufreq_unregister_driver(cpufreq_us3_driver);
225		kfree(cpufreq_us3_driver);
226		cpufreq_us3_driver = NULL;
227		kfree(us3_freq_table);
228		us3_freq_table = NULL;
229	}
230}
231
232MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
233MODULE_DESCRIPTION("cpufreq driver for UltraSPARC-III");
234MODULE_LICENSE("GPL");
235
236module_init(us3_freq_init);
237module_exit(us3_freq_exit);
238