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
 27MODULE_AUTHOR("Venkatesh Pallipadi");
 28MODULE_DESCRIPTION("ACPI Processor P-States Driver");
 29MODULE_LICENSE("GPL");
 30
 31struct cpufreq_acpi_io {
 32	struct acpi_processor_performance	acpi_data;
 33	unsigned int				resume;
 34};
 35
 36struct cpufreq_acpi_req {
 37	unsigned int		cpu;
 38	unsigned int		state;
 39};
 40
 41static struct cpufreq_acpi_io	*acpi_io_data[NR_CPUS];
 42
 43static struct cpufreq_driver acpi_cpufreq_driver;
 44
 45
 46static int
 47processor_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%llx\n",
 58		        value, retval);
 59		return -ENODEV;
 60	}
 61	return (int)retval;
 62}
 63
 64
 65static int
 66processor_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%llx, 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 */
 87static unsigned
 88extract_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
104static long
105processor_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
128static long
129processor_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
174static unsigned int
175acpi_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
188static int
189acpi_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
201static int
202acpi_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
305static int
306acpi_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
324static 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
335static int __init
336acpi_cpufreq_init (void)
337{
338	pr_debug("acpi_cpufreq_init\n");
339
340 	return cpufreq_register_driver(&acpi_cpufreq_driver);
341}
342
343
344static void __exit
345acpi_cpufreq_exit (void)
346{
347	pr_debug("acpi_cpufreq_exit\n");
348
349	cpufreq_unregister_driver(&acpi_cpufreq_driver);
350}
351
352late_initcall(acpi_cpufreq_init);
353module_exit(acpi_cpufreq_exit);