1/*
  2 * CPPC (Collaborative Processor Performance Control) driver for
  3 * interfacing with the CPUfreq layer and governors. See
  4 * cppc_acpi.c for CPPC specific methods.
  5 *
  6 * (C) Copyright 2014, 2015 Linaro Ltd.
  7 * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
  8 *
  9 * This program is free software; you can redistribute it and/or
 10 * modify it under the terms of the GNU General Public License
 11 * as published by the Free Software Foundation; version 2
 12 * of the License.
 13 */
 14
 15#define pr_fmt(fmt)	"CPPC Cpufreq:"	fmt
 16
 17#include <linux/kernel.h>
 18#include <linux/module.h>
 19#include <linux/delay.h>
 20#include <linux/cpu.h>
 21#include <linux/cpufreq.h>
 22#include <linux/dmi.h>
 23#include <linux/time.h>
 24#include <linux/vmalloc.h>
 25
 26#include <asm/unaligned.h>
 27
 28#include <acpi/cppc_acpi.h>
 29
 30/* Minimum struct length needed for the DMI processor entry we want */
 31#define DMI_ENTRY_PROCESSOR_MIN_LENGTH	48
 32
 33/* Offest in the DMI processor structure for the max frequency */
 34#define DMI_PROCESSOR_MAX_SPEED  0x14
 35
 36/*
 37 * These structs contain information parsed from per CPU
 38 * ACPI _CPC structures.
 39 * e.g. For each CPU the highest, lowest supported
 40 * performance capabilities, desired performance level
 41 * requested etc.
 42 */
 43static struct cppc_cpudata **all_cpu_data;
 44
 45/* Capture the max KHz from DMI */
 46static u64 cppc_dmi_max_khz;
 47
 48/* Callback function used to retrieve the max frequency from DMI */
 49static void cppc_find_dmi_mhz(const struct dmi_header *dm, void *private)
 50{
 51	const u8 *dmi_data = (const u8 *)dm;
 52	u16 *mhz = (u16 *)private;
 53
 54	if (dm->type == DMI_ENTRY_PROCESSOR &&
 55	    dm->length >= DMI_ENTRY_PROCESSOR_MIN_LENGTH) {
 56		u16 val = (u16)get_unaligned((const u16 *)
 57				(dmi_data + DMI_PROCESSOR_MAX_SPEED));
 58		*mhz = val > *mhz ? val : *mhz;
 59	}
 60}
 61
 62/* Look up the max frequency in DMI */
 63static u64 cppc_get_dmi_max_khz(void)
 64{
 65	u16 mhz = 0;
 66
 67	dmi_walk(cppc_find_dmi_mhz, &mhz);
 68
 69	/*
 70	 * Real stupid fallback value, just in case there is no
 71	 * actual value set.
 72	 */
 73	mhz = mhz ? mhz : 1;
 74
 75	return (1000 * mhz);
 76}
 77
 78static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
 79		unsigned int target_freq,
 80		unsigned int relation)
 81{
 82	struct cppc_cpudata *cpu;
 83	struct cpufreq_freqs freqs;
 84	u32 desired_perf;
 85	int ret = 0;
 86
 87	cpu = all_cpu_data[policy->cpu];
 88
 89	desired_perf = (u64)target_freq * cpu->perf_caps.highest_perf / cppc_dmi_max_khz;
 90	/* Return if it is exactly the same perf */
 91	if (desired_perf == cpu->perf_ctrls.desired_perf)
 92		return ret;
 93
 94	cpu->perf_ctrls.desired_perf = desired_perf;
 95	freqs.old = policy->cur;
 96	freqs.new = target_freq;
 97
 98	cpufreq_freq_transition_begin(policy, &freqs);
 99	ret = cppc_set_perf(cpu->cpu, &cpu->perf_ctrls);
100	cpufreq_freq_transition_end(policy, &freqs, ret != 0);
101
102	if (ret)
103		pr_debug("Failed to set target on CPU:%d. ret:%d\n",
104				cpu->cpu, ret);
105
106	return ret;
107}
108
109static int cppc_verify_policy(struct cpufreq_policy *policy)
110{
111	cpufreq_verify_within_cpu_limits(policy);
112	return 0;
113}
114
115static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)
116{
117	int cpu_num = policy->cpu;
118	struct cppc_cpudata *cpu = all_cpu_data[cpu_num];
119	int ret;
120
121	cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;
122
123	ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
124	if (ret)
125		pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
126				cpu->perf_caps.lowest_perf, cpu_num, ret);
127}
128
129/*
130 * The PCC subspace describes the rate at which platform can accept commands
131 * on the shared PCC channel (including READs which do not count towards freq
132 * trasition requests), so ideally we need to use the PCC values as a fallback
133 * if we don't have a platform specific transition_delay_us
134 */
135#ifdef CONFIG_ARM64
136#include <asm/cputype.h>
137
138static unsigned int cppc_cpufreq_get_transition_delay_us(int cpu)
139{
140	unsigned long implementor = read_cpuid_implementor();
141	unsigned long part_num = read_cpuid_part_number();
142	unsigned int delay_us = 0;
143
144	switch (implementor) {
145	case ARM_CPU_IMP_QCOM:
146		switch (part_num) {
147		case QCOM_CPU_PART_FALKOR_V1:
148		case QCOM_CPU_PART_FALKOR:
149			delay_us = 10000;
150			break;
151		default:
152			delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
153			break;
154		}
155		break;
156	default:
157		delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
158		break;
159	}
160
161	return delay_us;
162}
163
164#else
165
166static unsigned int cppc_cpufreq_get_transition_delay_us(int cpu)
167{
168	return cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
169}
170#endif
171
172static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
173{
174	struct cppc_cpudata *cpu;
175	unsigned int cpu_num = policy->cpu;
176	int ret = 0;
177
178	cpu = all_cpu_data[policy->cpu];
179
180	cpu->cpu = cpu_num;
181	ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps);
182
183	if (ret) {
184		pr_debug("Err reading CPU%d perf capabilities. ret:%d\n",
185				cpu_num, ret);
186		return ret;
187	}
188
189	cppc_dmi_max_khz = cppc_get_dmi_max_khz();
190
191	/*
192	 * Set min to lowest nonlinear perf to avoid any efficiency penalty (see
193	 * Section 8.4.7.1.1.5 of ACPI 6.1 spec)
194	 */
195	policy->min = cpu->perf_caps.lowest_nonlinear_perf * cppc_dmi_max_khz /
196		cpu->perf_caps.highest_perf;
197	policy->max = cppc_dmi_max_khz;
198
199	/*
200	 * Set cpuinfo.min_freq to Lowest to make the full range of performance
201	 * available if userspace wants to use any perf between lowest & lowest
202	 * nonlinear perf
203	 */
204	policy->cpuinfo.min_freq = cpu->perf_caps.lowest_perf * cppc_dmi_max_khz /
205		cpu->perf_caps.highest_perf;
206	policy->cpuinfo.max_freq = cppc_dmi_max_khz;
207
208	policy->transition_delay_us = cppc_cpufreq_get_transition_delay_us(cpu_num);
209	policy->shared_type = cpu->shared_type;
210
211	if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) {
212		int i;
213
214		cpumask_copy(policy->cpus, cpu->shared_cpu_map);
215
216		for_each_cpu(i, policy->cpus) {
217			if (unlikely(i == policy->cpu))
218				continue;
219
220			memcpy(&all_cpu_data[i]->perf_caps, &cpu->perf_caps,
221			       sizeof(cpu->perf_caps));
222		}
223	} else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) {
224		/* Support only SW_ANY for now. */
225		pr_debug("Unsupported CPU co-ord type\n");
226		return -EFAULT;
227	}
228
229	cpu->cur_policy = policy;
230
231	/* Set policy->cur to max now. The governors will adjust later. */
232	policy->cur = cppc_dmi_max_khz;
233	cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf;
234
235	ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
236	if (ret)
237		pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
238				cpu->perf_caps.highest_perf, cpu_num, ret);
239
240	return ret;
241}
242
243static struct cpufreq_driver cppc_cpufreq_driver = {
244	.flags = CPUFREQ_CONST_LOOPS,
245	.verify = cppc_verify_policy,
246	.target = cppc_cpufreq_set_target,
247	.init = cppc_cpufreq_cpu_init,
248	.stop_cpu = cppc_cpufreq_stop_cpu,
249	.name = "cppc_cpufreq",
250};
251
252static int __init cppc_cpufreq_init(void)
253{
254	int i, ret = 0;
255	struct cppc_cpudata *cpu;
256
257	if (acpi_disabled)
258		return -ENODEV;
259
260	all_cpu_data = kzalloc(sizeof(void *) * num_possible_cpus(), GFP_KERNEL);
261	if (!all_cpu_data)
262		return -ENOMEM;
263
264	for_each_possible_cpu(i) {
265		all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL);
266		if (!all_cpu_data[i])
267			goto out;
268
269		cpu = all_cpu_data[i];
270		if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL))
271			goto out;
272	}
273
274	ret = acpi_get_psd_map(all_cpu_data);
275	if (ret) {
276		pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n");
277		goto out;
278	}
279
280	ret = cpufreq_register_driver(&cppc_cpufreq_driver);
281	if (ret)
282		goto out;
283
284	return ret;
285
286out:
287	for_each_possible_cpu(i) {
288		cpu = all_cpu_data[i];
289		if (!cpu)
290			break;
291		free_cpumask_var(cpu->shared_cpu_map);
292		kfree(cpu);
293	}
294
295	kfree(all_cpu_data);
296	return -ENODEV;
297}
298
299static void __exit cppc_cpufreq_exit(void)
300{
301	struct cppc_cpudata *cpu;
302	int i;
303
304	cpufreq_unregister_driver(&cppc_cpufreq_driver);
305
306	for_each_possible_cpu(i) {
307		cpu = all_cpu_data[i];
308		free_cpumask_var(cpu->shared_cpu_map);
309		kfree(cpu);
310	}
311
312	kfree(all_cpu_data);
313}
314
315module_exit(cppc_cpufreq_exit);
316MODULE_AUTHOR("Ashwin Chaugule");
317MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec");
318MODULE_LICENSE("GPL");
319
320late_initcall(cppc_cpufreq_init);
321
322static const struct acpi_device_id cppc_acpi_ids[] = {
323	{ACPI_PROCESSOR_DEVICE_HID, },
324	{}
325};
326
327MODULE_DEVICE_TABLE(acpi, cppc_acpi_ids);