1/*
  2 * Copyright 2013 Freescale Semiconductor, Inc.
  3 *
  4 * CPU Frequency Scaling driver for Freescale PowerPC corenet SoCs.
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License version 2 as
  8 * published by the Free Software Foundation.
  9 */
 10
 11#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
 12
 13#include <linux/clk.h>
 14#include <linux/cpufreq.h>
 15#include <linux/errno.h>
 16#include <linux/init.h>
 17#include <linux/kernel.h>
 18#include <linux/module.h>
 19#include <linux/mutex.h>
 20#include <linux/of.h>
 21#include <linux/slab.h>
 22#include <linux/smp.h>
 23#include <sysdev/fsl_soc.h>
 24
 25/**
 26 * struct cpu_data - per CPU data struct
 27 * @parent: the parent node of cpu clock
 28 * @table: frequency table
 29 */
 30struct cpu_data {
 31	struct device_node *parent;
 32	struct cpufreq_frequency_table *table;
 33};
 34
 35/**
 36 * struct soc_data - SoC specific data
 37 * @freq_mask: mask the disallowed frequencies
 38 * @flag: unique flags
 39 */
 40struct soc_data {
 41	u32 freq_mask[4];
 42	u32 flag;
 43};
 44
 45#define FREQ_MASK	1
 46/* see hardware specification for the allowed frqeuencies */
 47static const struct soc_data sdata[] = {
 48	{ /* used by p2041 and p3041 */
 49		.freq_mask = {0x8, 0x8, 0x2, 0x2},
 50		.flag = FREQ_MASK,
 51	},
 52	{ /* used by p5020 */
 53		.freq_mask = {0x8, 0x2},
 54		.flag = FREQ_MASK,
 55	},
 56	{ /* used by p4080, p5040 */
 57		.freq_mask = {0},
 58		.flag = 0,
 59	},
 60};
 61
 62/*
 63 * the minimum allowed core frequency, in Hz
 64 * for chassis v1.0, >= platform frequency
 65 * for chassis v2.0, >= platform frequency / 2
 66 */
 67static u32 min_cpufreq;
 68static const u32 *fmask;
 69
 70static DEFINE_PER_CPU(struct cpu_data *, cpu_data);
 71
 72/* cpumask in a cluster */
 73static DEFINE_PER_CPU(cpumask_var_t, cpu_mask);
 74
 75#ifndef CONFIG_SMP
 76static inline const struct cpumask *cpu_core_mask(int cpu)
 77{
 78	return cpumask_of(0);
 79}
 80#endif
 81
 82/* reduce the duplicated frequencies in frequency table */
 83static void freq_table_redup(struct cpufreq_frequency_table *freq_table,
 84		int count)
 85{
 86	int i, j;
 87
 88	for (i = 1; i < count; i++) {
 89		for (j = 0; j < i; j++) {
 90			if (freq_table[j].frequency == CPUFREQ_ENTRY_INVALID ||
 91					freq_table[j].frequency !=
 92					freq_table[i].frequency)
 93				continue;
 94
 95			freq_table[i].frequency = CPUFREQ_ENTRY_INVALID;
 96			break;
 97		}
 98	}
 99}
100
101/* sort the frequencies in frequency table in descenting order */
102static void freq_table_sort(struct cpufreq_frequency_table *freq_table,
103		int count)
104{
105	int i, j, ind;
106	unsigned int freq, max_freq;
107	struct cpufreq_frequency_table table;
108	for (i = 0; i < count - 1; i++) {
109		max_freq = freq_table[i].frequency;
110		ind = i;
111		for (j = i + 1; j < count; j++) {
112			freq = freq_table[j].frequency;
113			if (freq == CPUFREQ_ENTRY_INVALID ||
114					freq <= max_freq)
115				continue;
116			ind = j;
117			max_freq = freq;
118		}
119
120		if (ind != i) {
121			/* exchange the frequencies */
122			table.driver_data = freq_table[i].driver_data;
123			table.frequency = freq_table[i].frequency;
124			freq_table[i].driver_data = freq_table[ind].driver_data;
125			freq_table[i].frequency = freq_table[ind].frequency;
126			freq_table[ind].driver_data = table.driver_data;
127			freq_table[ind].frequency = table.frequency;
128		}
129	}
130}
131
132static int corenet_cpufreq_cpu_init(struct cpufreq_policy *policy)
133{
134	struct device_node *np;
135	int i, count, ret;
136	u32 freq, mask;
137	struct clk *clk;
138	struct cpufreq_frequency_table *table;
139	struct cpu_data *data;
140	unsigned int cpu = policy->cpu;
141	u64 transition_latency_hz;
142
143	np = of_get_cpu_node(cpu, NULL);
144	if (!np)
145		return -ENODEV;
146
147	data = kzalloc(sizeof(*data), GFP_KERNEL);
148	if (!data) {
149		pr_err("%s: no memory\n", __func__);
150		goto err_np;
151	}
152
153	policy->clk = of_clk_get(np, 0);
154	if (IS_ERR(policy->clk)) {
155		pr_err("%s: no clock information\n", __func__);
156		goto err_nomem2;
157	}
158
159	data->parent = of_parse_phandle(np, "clocks", 0);
160	if (!data->parent) {
161		pr_err("%s: could not get clock information\n", __func__);
162		goto err_nomem2;
163	}
164
165	count = of_property_count_strings(data->parent, "clock-names");
166	table = kcalloc(count + 1, sizeof(*table), GFP_KERNEL);
167	if (!table) {
168		pr_err("%s: no memory\n", __func__);
169		goto err_node;
170	}
171
172	if (fmask)
173		mask = fmask[get_hard_smp_processor_id(cpu)];
174	else
175		mask = 0x0;
176
177	for (i = 0; i < count; i++) {
178		clk = of_clk_get(data->parent, i);
179		freq = clk_get_rate(clk);
180		/*
181		 * the clock is valid if its frequency is not masked
182		 * and large than minimum allowed frequency.
183		 */
184		if (freq < min_cpufreq || (mask & (1 << i)))
185			table[i].frequency = CPUFREQ_ENTRY_INVALID;
186		else
187			table[i].frequency = freq / 1000;
188		table[i].driver_data = i;
189	}
190	freq_table_redup(table, count);
191	freq_table_sort(table, count);
192	table[i].frequency = CPUFREQ_TABLE_END;
193
194	/* set the min and max frequency properly */
195	ret = cpufreq_table_validate_and_show(policy, table);
196	if (ret) {
197		pr_err("invalid frequency table: %d\n", ret);
198		goto err_nomem1;
199	}
200
201	data->table = table;
202	per_cpu(cpu_data, cpu) = data;
203
204	/* update ->cpus if we have cluster, no harm if not */
205	cpumask_copy(policy->cpus, per_cpu(cpu_mask, cpu));
206	for_each_cpu(i, per_cpu(cpu_mask, cpu))
207		per_cpu(cpu_data, i) = data;
208
209	transition_latency_hz = 12ULL * NSEC_PER_SEC;
210	policy->cpuinfo.transition_latency =
211		do_div(transition_latency_hz, fsl_get_sys_freq());
212
213	of_node_put(np);
214
215	return 0;
216
217err_nomem1:
218	kfree(table);
219err_node:
220	of_node_put(data->parent);
221err_nomem2:
222	per_cpu(cpu_data, cpu) = NULL;
223	kfree(data);
224err_np:
225	of_node_put(np);
226
227	return -ENODEV;
228}
229
230static int __exit corenet_cpufreq_cpu_exit(struct cpufreq_policy *policy)
231{
232	struct cpu_data *data = per_cpu(cpu_data, policy->cpu);
233	unsigned int cpu;
234
235	of_node_put(data->parent);
236	kfree(data->table);
237	kfree(data);
238
239	for_each_cpu(cpu, per_cpu(cpu_mask, policy->cpu))
240		per_cpu(cpu_data, cpu) = NULL;
241
242	return 0;
243}
244
245static int corenet_cpufreq_target(struct cpufreq_policy *policy,
246		unsigned int index)
247{
248	struct clk *parent;
249	struct cpu_data *data = per_cpu(cpu_data, policy->cpu);
250
251	parent = of_clk_get(data->parent, data->table[index].driver_data);
252	return clk_set_parent(policy->clk, parent);
253}
254
255static struct cpufreq_driver ppc_corenet_cpufreq_driver = {
256	.name		= "ppc_cpufreq",
257	.flags		= CPUFREQ_CONST_LOOPS,
258	.init		= corenet_cpufreq_cpu_init,
259	.exit		= __exit_p(corenet_cpufreq_cpu_exit),
260	.verify		= cpufreq_generic_frequency_table_verify,
261	.target_index	= corenet_cpufreq_target,
262	.get		= cpufreq_generic_get,
263	.attr		= cpufreq_generic_attr,
264};
265
266static const struct of_device_id node_matches[] __initdata = {
267	{ .compatible = "fsl,p2041-clockgen", .data = &sdata[0], },
268	{ .compatible = "fsl,p3041-clockgen", .data = &sdata[0], },
269	{ .compatible = "fsl,p5020-clockgen", .data = &sdata[1], },
270	{ .compatible = "fsl,p4080-clockgen", .data = &sdata[2], },
271	{ .compatible = "fsl,p5040-clockgen", .data = &sdata[2], },
272	{ .compatible = "fsl,qoriq-clockgen-2.0", },
273	{}
274};
275
276static int __init ppc_corenet_cpufreq_init(void)
277{
278	int ret;
279	struct device_node  *np;
280	const struct of_device_id *match;
281	const struct soc_data *data;
282	unsigned int cpu;
283
284	np = of_find_matching_node(NULL, node_matches);
285	if (!np)
286		return -ENODEV;
287
288	for_each_possible_cpu(cpu) {
289		if (!alloc_cpumask_var(&per_cpu(cpu_mask, cpu), GFP_KERNEL))
290			goto err_mask;
291		cpumask_copy(per_cpu(cpu_mask, cpu), cpu_core_mask(cpu));
292	}
293
294	match = of_match_node(node_matches, np);
295	data = match->data;
296	if (data) {
297		if (data->flag)
298			fmask = data->freq_mask;
299		min_cpufreq = fsl_get_sys_freq();
300	} else {
301		min_cpufreq = fsl_get_sys_freq() / 2;
302	}
303
304	of_node_put(np);
305
306	ret = cpufreq_register_driver(&ppc_corenet_cpufreq_driver);
307	if (!ret)
308		pr_info("Freescale PowerPC corenet CPU frequency scaling driver\n");
309
310	return ret;
311
312err_mask:
313	for_each_possible_cpu(cpu)
314		free_cpumask_var(per_cpu(cpu_mask, cpu));
315
316	return -ENOMEM;
317}
318module_init(ppc_corenet_cpufreq_init);
319
320static void __exit ppc_corenet_cpufreq_exit(void)
321{
322	unsigned int cpu;
323
324	for_each_possible_cpu(cpu)
325		free_cpumask_var(per_cpu(cpu_mask, cpu));
326
327	cpufreq_unregister_driver(&ppc_corenet_cpufreq_driver);
328}
329module_exit(ppc_corenet_cpufreq_exit);
330
331MODULE_LICENSE("GPL");
332MODULE_AUTHOR("Tang Yuantian <Yuantian.Tang@freescale.com>");
333MODULE_DESCRIPTION("cpufreq driver for Freescale e500mc series SoCs");