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/vmalloc.h>
 24
 25#include <asm/unaligned.h>
 26
 27#include <acpi/cppc_acpi.h>
 28
 29/* Minimum struct length needed for the DMI processor entry we want */
 30#define DMI_ENTRY_PROCESSOR_MIN_LENGTH	48
 31
 32/* Offest in the DMI processor structure for the max frequency */
 33#define DMI_PROCESSOR_MAX_SPEED  0x14
 34
 35/*
 36 * These structs contain information parsed from per CPU
 37 * ACPI _CPC structures.
 38 * e.g. For each CPU the highest, lowest supported
 39 * performance capabilities, desired performance level
 40 * requested etc.
 41 */
 42static struct cppc_cpudata **all_cpu_data;
 43
 44/* Capture the max KHz from DMI */
 45static u64 cppc_dmi_max_khz;
 46
 47/* Callback function used to retrieve the max frequency from DMI */
 48static void cppc_find_dmi_mhz(const struct dmi_header *dm, void *private)
 49{
 50	const u8 *dmi_data = (const u8 *)dm;
 51	u16 *mhz = (u16 *)private;
 52
 53	if (dm->type == DMI_ENTRY_PROCESSOR &&
 54	    dm->length >= DMI_ENTRY_PROCESSOR_MIN_LENGTH) {
 55		u16 val = (u16)get_unaligned((const u16 *)
 56				(dmi_data + DMI_PROCESSOR_MAX_SPEED));
 57		*mhz = val > *mhz ? val : *mhz;
 58	}
 59}
 60
 61/* Look up the max frequency in DMI */
 62static u64 cppc_get_dmi_max_khz(void)
 63{
 64	u16 mhz = 0;
 65
 66	dmi_walk(cppc_find_dmi_mhz, &mhz);
 67
 68	/*
 69	 * Real stupid fallback value, just in case there is no
 70	 * actual value set.
 71	 */
 72	mhz = mhz ? mhz : 1;
 73
 74	return (1000 * mhz);
 75}
 76
 77static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
 78		unsigned int target_freq,
 79		unsigned int relation)
 80{
 81	struct cppc_cpudata *cpu;
 82	struct cpufreq_freqs freqs;
 83	u32 desired_perf;
 84	int ret = 0;
 85
 86	cpu = all_cpu_data[policy->cpu];
 87
 88	desired_perf = (u64)target_freq * cpu->perf_caps.highest_perf / cppc_dmi_max_khz;
 89	/* Return if it is exactly the same perf */
 90	if (desired_perf == cpu->perf_ctrls.desired_perf)
 91		return ret;
 92
 93	cpu->perf_ctrls.desired_perf = desired_perf;
 94	freqs.old = policy->cur;
 95	freqs.new = target_freq;
 96
 97	cpufreq_freq_transition_begin(policy, &freqs);
 98	ret = cppc_set_perf(cpu->cpu, &cpu->perf_ctrls);
 99	cpufreq_freq_transition_end(policy, &freqs, ret != 0);
100
101	if (ret)
102		pr_debug("Failed to set target on CPU:%d. ret:%d\n",
103				cpu->cpu, ret);
104
105	return ret;
106}
107
108static int cppc_verify_policy(struct cpufreq_policy *policy)
109{
110	cpufreq_verify_within_cpu_limits(policy);
111	return 0;
112}
113
114static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)
115{
116	int cpu_num = policy->cpu;
117	struct cppc_cpudata *cpu = all_cpu_data[cpu_num];
118	int ret;
119
120	cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;
121
122	ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
123	if (ret)
124		pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
125				cpu->perf_caps.lowest_perf, cpu_num, ret);
126}
127
128static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
129{
130	struct cppc_cpudata *cpu;
131	unsigned int cpu_num = policy->cpu;
132	int ret = 0;
133
134	cpu = all_cpu_data[policy->cpu];
135
136	cpu->cpu = cpu_num;
137	ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps);
138
139	if (ret) {
140		pr_debug("Err reading CPU%d perf capabilities. ret:%d\n",
141				cpu_num, ret);
142		return ret;
143	}
144
145	cppc_dmi_max_khz = cppc_get_dmi_max_khz();
146
147	policy->min = cpu->perf_caps.lowest_perf * cppc_dmi_max_khz / cpu->perf_caps.highest_perf;
148	policy->max = cppc_dmi_max_khz;
149	policy->cpuinfo.min_freq = policy->min;
150	policy->cpuinfo.max_freq = policy->max;
151	policy->cpuinfo.transition_latency = cppc_get_transition_latency(cpu_num);
152	policy->shared_type = cpu->shared_type;
153
154	if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
155		cpumask_copy(policy->cpus, cpu->shared_cpu_map);
156	else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) {
157		/* Support only SW_ANY for now. */
158		pr_debug("Unsupported CPU co-ord type\n");
159		return -EFAULT;
160	}
161
162	cpumask_set_cpu(policy->cpu, policy->cpus);
163	cpu->cur_policy = policy;
164
165	/* Set policy->cur to max now. The governors will adjust later. */
166	policy->cur = cppc_dmi_max_khz;
167	cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf;
168
169	ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
170	if (ret)
171		pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
172				cpu->perf_caps.highest_perf, cpu_num, ret);
173
174	return ret;
175}
176
177static struct cpufreq_driver cppc_cpufreq_driver = {
178	.flags = CPUFREQ_CONST_LOOPS,
179	.verify = cppc_verify_policy,
180	.target = cppc_cpufreq_set_target,
181	.init = cppc_cpufreq_cpu_init,
182	.stop_cpu = cppc_cpufreq_stop_cpu,
183	.name = "cppc_cpufreq",
184};
185
186static int __init cppc_cpufreq_init(void)
187{
188	int i, ret = 0;
189	struct cppc_cpudata *cpu;
190
191	if (acpi_disabled)
192		return -ENODEV;
193
194	all_cpu_data = kzalloc(sizeof(void *) * num_possible_cpus(), GFP_KERNEL);
195	if (!all_cpu_data)
196		return -ENOMEM;
197
198	for_each_possible_cpu(i) {
199		all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL);
200		if (!all_cpu_data[i])
201			goto out;
202
203		cpu = all_cpu_data[i];
204		if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL))
205			goto out;
206	}
207
208	ret = acpi_get_psd_map(all_cpu_data);
209	if (ret) {
210		pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n");
211		goto out;
212	}
213
214	ret = cpufreq_register_driver(&cppc_cpufreq_driver);
215	if (ret)
216		goto out;
217
218	return ret;
219
220out:
221	for_each_possible_cpu(i)
222		kfree(all_cpu_data[i]);
223
224	kfree(all_cpu_data);
225	return -ENODEV;
226}
227
228static void __exit cppc_cpufreq_exit(void)
229{
230	struct cppc_cpudata *cpu;
231	int i;
232
233	cpufreq_unregister_driver(&cppc_cpufreq_driver);
234
235	for_each_possible_cpu(i) {
236		cpu = all_cpu_data[i];
237		free_cpumask_var(cpu->shared_cpu_map);
238		kfree(cpu);
239	}
240
241	kfree(all_cpu_data);
242}
243
244module_exit(cppc_cpufreq_exit);
245MODULE_AUTHOR("Ashwin Chaugule");
246MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec");
247MODULE_LICENSE("GPL");
248
249late_initcall(cppc_cpufreq_init);
250
251static const struct acpi_device_id cppc_acpi_ids[] = {
252	{ACPI_PROCESSOR_DEVICE_HID, },
253	{}
254};
255
256MODULE_DEVICE_TABLE(acpi, cppc_acpi_ids);