1/*
2 * Copyright (C) 2012 Freescale Semiconductor, Inc.
3 *
4 * Copyright (C) 2014 Linaro.
5 * Viresh Kumar <viresh.kumar@linaro.org>
6 *
7 * The OPP code in function set_target() is reused from
8 * drivers/cpufreq/omap-cpufreq.c
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 */
14
15#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
16
17#include <linux/clk.h>
18#include <linux/cpu.h>
19#include <linux/cpu_cooling.h>
20#include <linux/cpufreq.h>
21#include <linux/cpufreq-dt.h>
22#include <linux/cpumask.h>
23#include <linux/err.h>
24#include <linux/module.h>
25#include <linux/of.h>
26#include <linux/pm_opp.h>
27#include <linux/platform_device.h>
28#include <linux/regulator/consumer.h>
29#include <linux/slab.h>
30#include <linux/thermal.h>
31
32struct private_data {
33	struct device *cpu_dev;
34	struct regulator *cpu_reg;
35	struct thermal_cooling_device *cdev;
36	unsigned int voltage_tolerance; /* in percentage */
37};
38
39static int set_target(struct cpufreq_policy *policy, unsigned int index)
40{
41	struct dev_pm_opp *opp;
42	struct cpufreq_frequency_table *freq_table = policy->freq_table;
43	struct clk *cpu_clk = policy->clk;
44	struct private_data *priv = policy->driver_data;
45	struct device *cpu_dev = priv->cpu_dev;
46	struct regulator *cpu_reg = priv->cpu_reg;
47	unsigned long volt = 0, volt_old = 0, tol = 0;
48	unsigned int old_freq, new_freq;
49	long freq_Hz, freq_exact;
50	int ret;
51
52	freq_Hz = clk_round_rate(cpu_clk, freq_table[index].frequency * 1000);
53	if (freq_Hz <= 0)
54		freq_Hz = freq_table[index].frequency * 1000;
55
56	freq_exact = freq_Hz;
57	new_freq = freq_Hz / 1000;
58	old_freq = clk_get_rate(cpu_clk) / 1000;
59
60	if (!IS_ERR(cpu_reg)) {
61		rcu_read_lock();
62		opp = dev_pm_opp_find_freq_ceil(cpu_dev, &freq_Hz);
63		if (IS_ERR(opp)) {
64			rcu_read_unlock();
65			dev_err(cpu_dev, "failed to find OPP for %ld\n",
66				freq_Hz);
67			return PTR_ERR(opp);
68		}
69		volt = dev_pm_opp_get_voltage(opp);
70		rcu_read_unlock();
71		tol = volt * priv->voltage_tolerance / 100;
72		volt_old = regulator_get_voltage(cpu_reg);
73	}
74
75	dev_dbg(cpu_dev, "%u MHz, %ld mV --> %u MHz, %ld mV\n",
76		old_freq / 1000, volt_old ? volt_old / 1000 : -1,
77		new_freq / 1000, volt ? volt / 1000 : -1);
78
79	/* scaling up?  scale voltage before frequency */
80	if (!IS_ERR(cpu_reg) && new_freq > old_freq) {
81		ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
82		if (ret) {
83			dev_err(cpu_dev, "failed to scale voltage up: %d\n",
84				ret);
85			return ret;
86		}
87	}
88
89	ret = clk_set_rate(cpu_clk, freq_exact);
90	if (ret) {
91		dev_err(cpu_dev, "failed to set clock rate: %d\n", ret);
92		if (!IS_ERR(cpu_reg))
93			regulator_set_voltage_tol(cpu_reg, volt_old, tol);
94		return ret;
95	}
96
97	/* scaling down?  scale voltage after frequency */
98	if (!IS_ERR(cpu_reg) && new_freq < old_freq) {
99		ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
100		if (ret) {
101			dev_err(cpu_dev, "failed to scale voltage down: %d\n",
102				ret);
103			clk_set_rate(cpu_clk, old_freq * 1000);
104		}
105	}
106
107	return ret;
108}
109
110static int allocate_resources(int cpu, struct device **cdev,
111			      struct regulator **creg, struct clk **cclk)
112{
113	struct device *cpu_dev;
114	struct regulator *cpu_reg;
115	struct clk *cpu_clk;
116	int ret = 0;
117	char *reg_cpu0 = "cpu0", *reg_cpu = "cpu", *reg;
118
119	cpu_dev = get_cpu_device(cpu);
120	if (!cpu_dev) {
121		pr_err("failed to get cpu%d device\n", cpu);
122		return -ENODEV;
123	}
124
125	/* Try "cpu0" for older DTs */
126	if (!cpu)
127		reg = reg_cpu0;
128	else
129		reg = reg_cpu;
130
131try_again:
132	cpu_reg = regulator_get_optional(cpu_dev, reg);
133	if (IS_ERR(cpu_reg)) {
134		/*
135		 * If cpu's regulator supply node is present, but regulator is
136		 * not yet registered, we should try defering probe.
137		 */
138		if (PTR_ERR(cpu_reg) == -EPROBE_DEFER) {
139			dev_dbg(cpu_dev, "cpu%d regulator not ready, retry\n",
140				cpu);
141			return -EPROBE_DEFER;
142		}
143
144		/* Try with "cpu-supply" */
145		if (reg == reg_cpu0) {
146			reg = reg_cpu;
147			goto try_again;
148		}
149
150		dev_dbg(cpu_dev, "no regulator for cpu%d: %ld\n",
151			cpu, PTR_ERR(cpu_reg));
152	}
153
154	cpu_clk = clk_get(cpu_dev, NULL);
155	if (IS_ERR(cpu_clk)) {
156		/* put regulator */
157		if (!IS_ERR(cpu_reg))
158			regulator_put(cpu_reg);
159
160		ret = PTR_ERR(cpu_clk);
161
162		/*
163		 * If cpu's clk node is present, but clock is not yet
164		 * registered, we should try defering probe.
165		 */
166		if (ret == -EPROBE_DEFER)
167			dev_dbg(cpu_dev, "cpu%d clock not ready, retry\n", cpu);
168		else
169			dev_err(cpu_dev, "failed to get cpu%d clock: %d\n", cpu,
170				ret);
171	} else {
172		*cdev = cpu_dev;
173		*creg = cpu_reg;
174		*cclk = cpu_clk;
175	}
176
177	return ret;
178}
179
180static int cpufreq_init(struct cpufreq_policy *policy)
181{
182	struct cpufreq_dt_platform_data *pd;
183	struct cpufreq_frequency_table *freq_table;
184	struct thermal_cooling_device *cdev;
185	struct device_node *np;
186	struct private_data *priv;
187	struct device *cpu_dev;
188	struct regulator *cpu_reg;
189	struct clk *cpu_clk;
190	unsigned long min_uV = ~0, max_uV = 0;
191	unsigned int transition_latency;
192	int ret;
193
194	ret = allocate_resources(policy->cpu, &cpu_dev, &cpu_reg, &cpu_clk);
195	if (ret) {
196		pr_err("%s: Failed to allocate resources\n: %d", __func__, ret);
197		return ret;
198	}
199
200	np = of_node_get(cpu_dev->of_node);
201	if (!np) {
202		dev_err(cpu_dev, "failed to find cpu%d node\n", policy->cpu);
203		ret = -ENOENT;
204		goto out_put_reg_clk;
205	}
206
207	/* OPPs might be populated at runtime, don't check for error here */
208	of_init_opp_table(cpu_dev);
209
210	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
211	if (!priv) {
212		ret = -ENOMEM;
213		goto out_put_node;
214	}
215
216	of_property_read_u32(np, "voltage-tolerance", &priv->voltage_tolerance);
217
218	if (of_property_read_u32(np, "clock-latency", &transition_latency))
219		transition_latency = CPUFREQ_ETERNAL;
220
221	if (!IS_ERR(cpu_reg)) {
222		unsigned long opp_freq = 0;
223
224		/*
225		 * Disable any OPPs where the connected regulator isn't able to
226		 * provide the specified voltage and record minimum and maximum
227		 * voltage levels.
228		 */
229		while (1) {
230			struct dev_pm_opp *opp;
231			unsigned long opp_uV, tol_uV;
232
233			rcu_read_lock();
234			opp = dev_pm_opp_find_freq_ceil(cpu_dev, &opp_freq);
235			if (IS_ERR(opp)) {
236				rcu_read_unlock();
237				break;
238			}
239			opp_uV = dev_pm_opp_get_voltage(opp);
240			rcu_read_unlock();
241
242			tol_uV = opp_uV * priv->voltage_tolerance / 100;
243			if (regulator_is_supported_voltage(cpu_reg, opp_uV,
244							   opp_uV + tol_uV)) {
245				if (opp_uV < min_uV)
246					min_uV = opp_uV;
247				if (opp_uV > max_uV)
248					max_uV = opp_uV;
249			} else {
250				dev_pm_opp_disable(cpu_dev, opp_freq);
251			}
252
253			opp_freq++;
254		}
255
256		ret = regulator_set_voltage_time(cpu_reg, min_uV, max_uV);
257		if (ret > 0)
258			transition_latency += ret * 1000;
259	}
260
261	ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
262	if (ret) {
263		pr_err("failed to init cpufreq table: %d\n", ret);
264		goto out_free_priv;
265	}
266
267	/*
268	 * For now, just loading the cooling device;
269	 * thermal DT code takes care of matching them.
270	 */
271	if (of_find_property(np, "#cooling-cells", NULL)) {
272		cdev = of_cpufreq_cooling_register(np, cpu_present_mask);
273		if (IS_ERR(cdev))
274			dev_err(cpu_dev,
275				"running cpufreq without cooling device: %ld\n",
276				PTR_ERR(cdev));
277		else
278			priv->cdev = cdev;
279	}
280
281	priv->cpu_dev = cpu_dev;
282	priv->cpu_reg = cpu_reg;
283	policy->driver_data = priv;
284
285	policy->clk = cpu_clk;
286	ret = cpufreq_table_validate_and_show(policy, freq_table);
287	if (ret) {
288		dev_err(cpu_dev, "%s: invalid frequency table: %d\n", __func__,
289			ret);
290		goto out_cooling_unregister;
291	}
292
293	policy->cpuinfo.transition_latency = transition_latency;
294
295	pd = cpufreq_get_driver_data();
296	if (!pd || !pd->independent_clocks)
297		cpumask_setall(policy->cpus);
298
299	of_node_put(np);
300
301	return 0;
302
303out_cooling_unregister:
304	cpufreq_cooling_unregister(priv->cdev);
305	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
306out_free_priv:
307	kfree(priv);
308out_put_node:
309	of_node_put(np);
310out_put_reg_clk:
311	clk_put(cpu_clk);
312	if (!IS_ERR(cpu_reg))
313		regulator_put(cpu_reg);
314
315	return ret;
316}
317
318static int cpufreq_exit(struct cpufreq_policy *policy)
319{
320	struct private_data *priv = policy->driver_data;
321
322	cpufreq_cooling_unregister(priv->cdev);
323	dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
324	clk_put(policy->clk);
325	if (!IS_ERR(priv->cpu_reg))
326		regulator_put(priv->cpu_reg);
327	kfree(priv);
328
329	return 0;
330}
331
332static struct cpufreq_driver dt_cpufreq_driver = {
333	.flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
334	.verify = cpufreq_generic_frequency_table_verify,
335	.target_index = set_target,
336	.get = cpufreq_generic_get,
337	.init = cpufreq_init,
338	.exit = cpufreq_exit,
339	.name = "cpufreq-dt",
340	.attr = cpufreq_generic_attr,
341};
342
343static int dt_cpufreq_probe(struct platform_device *pdev)
344{
345	struct device *cpu_dev;
346	struct regulator *cpu_reg;
347	struct clk *cpu_clk;
348	int ret;
349
350	/*
351	 * All per-cluster (CPUs sharing clock/voltages) initialization is done
352	 * from ->init(). In probe(), we just need to make sure that clk and
353	 * regulators are available. Else defer probe and retry.
354	 *
355	 * FIXME: Is checking this only for CPU0 sufficient ?
356	 */
357	ret = allocate_resources(0, &cpu_dev, &cpu_reg, &cpu_clk);
358	if (ret)
359		return ret;
360
361	clk_put(cpu_clk);
362	if (!IS_ERR(cpu_reg))
363		regulator_put(cpu_reg);
364
365	dt_cpufreq_driver.driver_data = dev_get_platdata(&pdev->dev);
366
367	ret = cpufreq_register_driver(&dt_cpufreq_driver);
368	if (ret)
369		dev_err(cpu_dev, "failed register driver: %d\n", ret);
370
371	return ret;
372}
373
374static int dt_cpufreq_remove(struct platform_device *pdev)
375{
376	cpufreq_unregister_driver(&dt_cpufreq_driver);
377	return 0;
378}
379
380static struct platform_driver dt_cpufreq_platdrv = {
381	.driver = {
382		.name	= "cpufreq-dt",
383		.owner	= THIS_MODULE,
384	},
385	.probe		= dt_cpufreq_probe,
386	.remove		= dt_cpufreq_remove,
387};
388module_platform_driver(dt_cpufreq_platdrv);
389
390MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
391MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
392MODULE_DESCRIPTION("Generic cpufreq driver");
393MODULE_LICENSE("GPL");
394