1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * This file provides the ACPI based P-state support. This
4  * module works with generic cpufreq infrastructure. Most of
5  * the code is based on i386 version
6  * (arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c)
7  *
8  * Copyright (C) 2005 Intel Corp
9  *      Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
10  */
11 
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 
14 #include <linux/kernel.h>
15 #include <linux/slab.h>
16 #include <linux/module.h>
17 #include <linux/init.h>
18 #include <linux/cpufreq.h>
19 #include <linux/proc_fs.h>
20 #include <asm/io.h>
21 #include <linux/uaccess.h>
22 #include <asm/pal.h>
23 
24 #include <linux/acpi.h>
25 #include <acpi/processor.h>
26 
27 MODULE_AUTHOR("Venkatesh Pallipadi");
28 MODULE_DESCRIPTION("ACPI Processor P-States Driver");
29 MODULE_LICENSE("GPL");
30 
31 struct cpufreq_acpi_io {
32 	struct acpi_processor_performance	acpi_data;
33 	unsigned int				resume;
34 };
35 
36 struct cpufreq_acpi_req {
37 	unsigned int		cpu;
38 	unsigned int		state;
39 };
40 
41 static struct cpufreq_acpi_io	*acpi_io_data[NR_CPUS];
42 
43 static struct cpufreq_driver acpi_cpufreq_driver;
44 
45 
46 static int
47 processor_set_pstate (
48 	u32	value)
49 {
50 	s64 retval;
51 
52 	pr_debug("processor_set_pstate\n");
53 
54 	retval = ia64_pal_set_pstate((u64)value);
55 
56 	if (retval) {
57 		pr_debug("Failed to set freq to 0x%x, with error 0x%lx\n",
58 		        value, retval);
59 		return -ENODEV;
60 	}
61 	return (int)retval;
62 }
63 
64 
65 static int
66 processor_get_pstate (
67 	u32	*value)
68 {
69 	u64	pstate_index = 0;
70 	s64 	retval;
71 
72 	pr_debug("processor_get_pstate\n");
73 
74 	retval = ia64_pal_get_pstate(&pstate_index,
75 	                             PAL_GET_PSTATE_TYPE_INSTANT);
76 	*value = (u32) pstate_index;
77 
78 	if (retval)
79 		pr_debug("Failed to get current freq with "
80 			"error 0x%lx, idx 0x%x\n", retval, *value);
81 
82 	return (int)retval;
83 }
84 
85 
86 /* To be used only after data->acpi_data is initialized */
87 static unsigned
88 extract_clock (
89 	struct cpufreq_acpi_io *data,
90 	unsigned value)
91 {
92 	unsigned long i;
93 
94 	pr_debug("extract_clock\n");
95 
96 	for (i = 0; i < data->acpi_data.state_count; i++) {
97 		if (value == data->acpi_data.states[i].status)
98 			return data->acpi_data.states[i].core_frequency;
99 	}
100 	return data->acpi_data.states[i-1].core_frequency;
101 }
102 
103 
104 static long
105 processor_get_freq (
106 	void *arg)
107 {
108 	struct cpufreq_acpi_req *req = arg;
109 	unsigned int		cpu = req->cpu;
110 	struct cpufreq_acpi_io	*data = acpi_io_data[cpu];
111 	u32			value;
112 	int			ret;
113 
114 	pr_debug("processor_get_freq\n");
115 	if (smp_processor_id() != cpu)
116 		return -EAGAIN;
117 
118 	/* processor_get_pstate gets the instantaneous frequency */
119 	ret = processor_get_pstate(&value);
120 	if (ret) {
121 		pr_warn("get performance failed with error %d\n", ret);
122 		return ret;
123 	}
124 	return 1000 * extract_clock(data, value);
125 }
126 
127 
128 static long
129 processor_set_freq (
130 	void *arg)
131 {
132 	struct cpufreq_acpi_req *req = arg;
133 	unsigned int		cpu = req->cpu;
134 	struct cpufreq_acpi_io	*data = acpi_io_data[cpu];
135 	int			ret, state = req->state;
136 	u32			value;
137 
138 	pr_debug("processor_set_freq\n");
139 	if (smp_processor_id() != cpu)
140 		return -EAGAIN;
141 
142 	if (state == data->acpi_data.state) {
143 		if (unlikely(data->resume)) {
144 			pr_debug("Called after resume, resetting to P%d\n", state);
145 			data->resume = 0;
146 		} else {
147 			pr_debug("Already at target state (P%d)\n", state);
148 			return 0;
149 		}
150 	}
151 
152 	pr_debug("Transitioning from P%d to P%d\n",
153 		data->acpi_data.state, state);
154 
155 	/*
156 	 * First we write the target state's 'control' value to the
157 	 * control_register.
158 	 */
159 	value = (u32) data->acpi_data.states[state].control;
160 
161 	pr_debug("Transitioning to state: 0x%08x\n", value);
162 
163 	ret = processor_set_pstate(value);
164 	if (ret) {
165 		pr_warn("Transition failed with error %d\n", ret);
166 		return -ENODEV;
167 	}
168 
169 	data->acpi_data.state = state;
170 	return 0;
171 }
172 
173 
174 static unsigned int
175 acpi_cpufreq_get (
176 	unsigned int		cpu)
177 {
178 	struct cpufreq_acpi_req req;
179 	long ret;
180 
181 	req.cpu = cpu;
182 	ret = work_on_cpu(cpu, processor_get_freq, &req);
183 
184 	return ret > 0 ? (unsigned int) ret : 0;
185 }
186 
187 
188 static int
189 acpi_cpufreq_target (
190 	struct cpufreq_policy   *policy,
191 	unsigned int index)
192 {
193 	struct cpufreq_acpi_req req;
194 
195 	req.cpu = policy->cpu;
196 	req.state = index;
197 
198 	return work_on_cpu(req.cpu, processor_set_freq, &req);
199 }
200 
201 static int
202 acpi_cpufreq_cpu_init (
203 	struct cpufreq_policy   *policy)
204 {
205 	unsigned int		i;
206 	unsigned int		cpu = policy->cpu;
207 	struct cpufreq_acpi_io	*data;
208 	unsigned int		result = 0;
209 	struct cpufreq_frequency_table *freq_table;
210 
211 	pr_debug("acpi_cpufreq_cpu_init\n");
212 
213 	data = kzalloc(sizeof(*data), GFP_KERNEL);
214 	if (!data)
215 		return (-ENOMEM);
216 
217 	acpi_io_data[cpu] = data;
218 
219 	result = acpi_processor_register_performance(&data->acpi_data, cpu);
220 
221 	if (result)
222 		goto err_free;
223 
224 	/* capability check */
225 	if (data->acpi_data.state_count <= 1) {
226 		pr_debug("No P-States\n");
227 		result = -ENODEV;
228 		goto err_unreg;
229 	}
230 
231 	if ((data->acpi_data.control_register.space_id !=
232 					ACPI_ADR_SPACE_FIXED_HARDWARE) ||
233 	    (data->acpi_data.status_register.space_id !=
234 					ACPI_ADR_SPACE_FIXED_HARDWARE)) {
235 		pr_debug("Unsupported address space [%d, %d]\n",
236 			(u32) (data->acpi_data.control_register.space_id),
237 			(u32) (data->acpi_data.status_register.space_id));
238 		result = -ENODEV;
239 		goto err_unreg;
240 	}
241 
242 	/* alloc freq_table */
243 	freq_table = kcalloc(data->acpi_data.state_count + 1,
244 	                           sizeof(*freq_table),
245 	                           GFP_KERNEL);
246 	if (!freq_table) {
247 		result = -ENOMEM;
248 		goto err_unreg;
249 	}
250 
251 	/* detect transition latency */
252 	policy->cpuinfo.transition_latency = 0;
253 	for (i=0; i<data->acpi_data.state_count; i++) {
254 		if ((data->acpi_data.states[i].transition_latency * 1000) >
255 		    policy->cpuinfo.transition_latency) {
256 			policy->cpuinfo.transition_latency =
257 			    data->acpi_data.states[i].transition_latency * 1000;
258 		}
259 	}
260 
261 	/* table init */
262 	for (i = 0; i <= data->acpi_data.state_count; i++)
263 	{
264 		if (i < data->acpi_data.state_count) {
265 			freq_table[i].frequency =
266 			      data->acpi_data.states[i].core_frequency * 1000;
267 		} else {
268 			freq_table[i].frequency = CPUFREQ_TABLE_END;
269 		}
270 	}
271 
272 	policy->freq_table = freq_table;
273 
274 	/* notify BIOS that we exist */
275 	acpi_processor_notify_smm(THIS_MODULE);
276 
277 	pr_info("CPU%u - ACPI performance management activated\n", cpu);
278 
279 	for (i = 0; i < data->acpi_data.state_count; i++)
280 		pr_debug("     %cP%d: %d MHz, %d mW, %d uS, %d uS, 0x%x 0x%x\n",
281 			(i == data->acpi_data.state?'*':' '), i,
282 			(u32) data->acpi_data.states[i].core_frequency,
283 			(u32) data->acpi_data.states[i].power,
284 			(u32) data->acpi_data.states[i].transition_latency,
285 			(u32) data->acpi_data.states[i].bus_master_latency,
286 			(u32) data->acpi_data.states[i].status,
287 			(u32) data->acpi_data.states[i].control);
288 
289 	/* the first call to ->target() should result in us actually
290 	 * writing something to the appropriate registers. */
291 	data->resume = 1;
292 
293 	return (result);
294 
295  err_unreg:
296 	acpi_processor_unregister_performance(cpu);
297  err_free:
298 	kfree(data);
299 	acpi_io_data[cpu] = NULL;
300 
301 	return (result);
302 }
303 
304 
305 static int
306 acpi_cpufreq_cpu_exit (
307 	struct cpufreq_policy   *policy)
308 {
309 	struct cpufreq_acpi_io *data = acpi_io_data[policy->cpu];
310 
311 	pr_debug("acpi_cpufreq_cpu_exit\n");
312 
313 	if (data) {
314 		acpi_io_data[policy->cpu] = NULL;
315 		acpi_processor_unregister_performance(policy->cpu);
316 		kfree(policy->freq_table);
317 		kfree(data);
318 	}
319 
320 	return (0);
321 }
322 
323 
324 static struct cpufreq_driver acpi_cpufreq_driver = {
325 	.verify 	= cpufreq_generic_frequency_table_verify,
326 	.target_index	= acpi_cpufreq_target,
327 	.get 		= acpi_cpufreq_get,
328 	.init		= acpi_cpufreq_cpu_init,
329 	.exit		= acpi_cpufreq_cpu_exit,
330 	.name		= "acpi-cpufreq",
331 	.attr		= cpufreq_generic_attr,
332 };
333 
334 
335 static int __init
336 acpi_cpufreq_init (void)
337 {
338 	pr_debug("acpi_cpufreq_init\n");
339 
340  	return cpufreq_register_driver(&acpi_cpufreq_driver);
341 }
342 
343 
344 static void __exit
345 acpi_cpufreq_exit (void)
346 {
347 	pr_debug("acpi_cpufreq_exit\n");
348 
349 	cpufreq_unregister_driver(&acpi_cpufreq_driver);
350 }
351 
352 late_initcall(acpi_cpufreq_init);
353 module_exit(acpi_cpufreq_exit);
354