1 /*
2  * Copyright 2013 Freescale Semiconductor, Inc.
3  *
4  * CPU Frequency Scaling driver for Freescale QorIQ 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 
24 #if !defined(CONFIG_ARM)
25 #include <asm/smp.h>	/* for get_hard_smp_processor_id() in UP configs */
26 #endif
27 
28 /**
29  * struct cpu_data
30  * @pclk: the parent clock of cpu
31  * @table: frequency table
32  */
33 struct cpu_data {
34 	struct clk **pclk;
35 	struct cpufreq_frequency_table *table;
36 };
37 
38 /**
39  * struct soc_data - SoC specific data
40  * @freq_mask: mask the disallowed frequencies
41  * @flag: unique flags
42  */
43 struct soc_data {
44 	u32 freq_mask[4];
45 	u32 flag;
46 };
47 
48 #define FREQ_MASK	1
49 /* see hardware specification for the allowed frqeuencies */
50 static const struct soc_data sdata[] = {
51 	{ /* used by p2041 and p3041 */
52 		.freq_mask = {0x8, 0x8, 0x2, 0x2},
53 		.flag = FREQ_MASK,
54 	},
55 	{ /* used by p5020 */
56 		.freq_mask = {0x8, 0x2},
57 		.flag = FREQ_MASK,
58 	},
59 	{ /* used by p4080, p5040 */
60 		.freq_mask = {0},
61 		.flag = 0,
62 	},
63 };
64 
65 /*
66  * the minimum allowed core frequency, in Hz
67  * for chassis v1.0, >= platform frequency
68  * for chassis v2.0, >= platform frequency / 2
69  */
70 static u32 min_cpufreq;
71 static const u32 *fmask;
72 
73 #if defined(CONFIG_ARM)
74 static int get_cpu_physical_id(int cpu)
75 {
76 	return topology_core_id(cpu);
77 }
78 #else
79 static int get_cpu_physical_id(int cpu)
80 {
81 	return get_hard_smp_processor_id(cpu);
82 }
83 #endif
84 
85 static u32 get_bus_freq(void)
86 {
87 	struct device_node *soc;
88 	u32 sysfreq;
89 
90 	soc = of_find_node_by_type(NULL, "soc");
91 	if (!soc)
92 		return 0;
93 
94 	if (of_property_read_u32(soc, "bus-frequency", &sysfreq))
95 		sysfreq = 0;
96 
97 	of_node_put(soc);
98 
99 	return sysfreq;
100 }
101 
102 static struct device_node *cpu_to_clk_node(int cpu)
103 {
104 	struct device_node *np, *clk_np;
105 
106 	if (!cpu_present(cpu))
107 		return NULL;
108 
109 	np = of_get_cpu_node(cpu, NULL);
110 	if (!np)
111 		return NULL;
112 
113 	clk_np = of_parse_phandle(np, "clocks", 0);
114 	if (!clk_np)
115 		return NULL;
116 
117 	of_node_put(np);
118 
119 	return clk_np;
120 }
121 
122 /* traverse cpu nodes to get cpu mask of sharing clock wire */
123 static void set_affected_cpus(struct cpufreq_policy *policy)
124 {
125 	struct device_node *np, *clk_np;
126 	struct cpumask *dstp = policy->cpus;
127 	int i;
128 
129 	np = cpu_to_clk_node(policy->cpu);
130 	if (!np)
131 		return;
132 
133 	for_each_present_cpu(i) {
134 		clk_np = cpu_to_clk_node(i);
135 		if (!clk_np)
136 			continue;
137 
138 		if (clk_np == np)
139 			cpumask_set_cpu(i, dstp);
140 
141 		of_node_put(clk_np);
142 	}
143 	of_node_put(np);
144 }
145 
146 /* reduce the duplicated frequencies in frequency table */
147 static void freq_table_redup(struct cpufreq_frequency_table *freq_table,
148 		int count)
149 {
150 	int i, j;
151 
152 	for (i = 1; i < count; i++) {
153 		for (j = 0; j < i; j++) {
154 			if (freq_table[j].frequency == CPUFREQ_ENTRY_INVALID ||
155 					freq_table[j].frequency !=
156 					freq_table[i].frequency)
157 				continue;
158 
159 			freq_table[i].frequency = CPUFREQ_ENTRY_INVALID;
160 			break;
161 		}
162 	}
163 }
164 
165 /* sort the frequencies in frequency table in descenting order */
166 static void freq_table_sort(struct cpufreq_frequency_table *freq_table,
167 		int count)
168 {
169 	int i, j, ind;
170 	unsigned int freq, max_freq;
171 	struct cpufreq_frequency_table table;
172 
173 	for (i = 0; i < count - 1; i++) {
174 		max_freq = freq_table[i].frequency;
175 		ind = i;
176 		for (j = i + 1; j < count; j++) {
177 			freq = freq_table[j].frequency;
178 			if (freq == CPUFREQ_ENTRY_INVALID ||
179 					freq <= max_freq)
180 				continue;
181 			ind = j;
182 			max_freq = freq;
183 		}
184 
185 		if (ind != i) {
186 			/* exchange the frequencies */
187 			table.driver_data = freq_table[i].driver_data;
188 			table.frequency = freq_table[i].frequency;
189 			freq_table[i].driver_data = freq_table[ind].driver_data;
190 			freq_table[i].frequency = freq_table[ind].frequency;
191 			freq_table[ind].driver_data = table.driver_data;
192 			freq_table[ind].frequency = table.frequency;
193 		}
194 	}
195 }
196 
197 static int qoriq_cpufreq_cpu_init(struct cpufreq_policy *policy)
198 {
199 	struct device_node *np, *pnode;
200 	int i, count, ret;
201 	u32 freq, mask;
202 	struct clk *clk;
203 	struct cpufreq_frequency_table *table;
204 	struct cpu_data *data;
205 	unsigned int cpu = policy->cpu;
206 	u64 u64temp;
207 
208 	np = of_get_cpu_node(cpu, NULL);
209 	if (!np)
210 		return -ENODEV;
211 
212 	data = kzalloc(sizeof(*data), GFP_KERNEL);
213 	if (!data)
214 		goto err_np;
215 
216 	policy->clk = of_clk_get(np, 0);
217 	if (IS_ERR(policy->clk)) {
218 		pr_err("%s: no clock information\n", __func__);
219 		goto err_nomem2;
220 	}
221 
222 	pnode = of_parse_phandle(np, "clocks", 0);
223 	if (!pnode) {
224 		pr_err("%s: could not get clock information\n", __func__);
225 		goto err_nomem2;
226 	}
227 
228 	count = of_property_count_strings(pnode, "clock-names");
229 	data->pclk = kcalloc(count, sizeof(struct clk *), GFP_KERNEL);
230 	if (!data->pclk) {
231 		pr_err("%s: no memory\n", __func__);
232 		goto err_node;
233 	}
234 
235 	table = kcalloc(count + 1, sizeof(*table), GFP_KERNEL);
236 	if (!table) {
237 		pr_err("%s: no memory\n", __func__);
238 		goto err_pclk;
239 	}
240 
241 	if (fmask)
242 		mask = fmask[get_cpu_physical_id(cpu)];
243 	else
244 		mask = 0x0;
245 
246 	for (i = 0; i < count; i++) {
247 		clk = of_clk_get(pnode, i);
248 		data->pclk[i] = clk;
249 		freq = clk_get_rate(clk);
250 		/*
251 		 * the clock is valid if its frequency is not masked
252 		 * and large than minimum allowed frequency.
253 		 */
254 		if (freq < min_cpufreq || (mask & (1 << i)))
255 			table[i].frequency = CPUFREQ_ENTRY_INVALID;
256 		else
257 			table[i].frequency = freq / 1000;
258 		table[i].driver_data = i;
259 	}
260 	freq_table_redup(table, count);
261 	freq_table_sort(table, count);
262 	table[i].frequency = CPUFREQ_TABLE_END;
263 
264 	/* set the min and max frequency properly */
265 	ret = cpufreq_table_validate_and_show(policy, table);
266 	if (ret) {
267 		pr_err("invalid frequency table: %d\n", ret);
268 		goto err_nomem1;
269 	}
270 
271 	data->table = table;
272 
273 	/* update ->cpus if we have cluster, no harm if not */
274 	set_affected_cpus(policy);
275 	policy->driver_data = data;
276 
277 	/* Minimum transition latency is 12 platform clocks */
278 	u64temp = 12ULL * NSEC_PER_SEC;
279 	do_div(u64temp, get_bus_freq());
280 	policy->cpuinfo.transition_latency = u64temp + 1;
281 
282 	of_node_put(np);
283 	of_node_put(pnode);
284 
285 	return 0;
286 
287 err_nomem1:
288 	kfree(table);
289 err_pclk:
290 	kfree(data->pclk);
291 err_node:
292 	of_node_put(pnode);
293 err_nomem2:
294 	policy->driver_data = NULL;
295 	kfree(data);
296 err_np:
297 	of_node_put(np);
298 
299 	return -ENODEV;
300 }
301 
302 static int __exit qoriq_cpufreq_cpu_exit(struct cpufreq_policy *policy)
303 {
304 	struct cpu_data *data = policy->driver_data;
305 
306 	kfree(data->pclk);
307 	kfree(data->table);
308 	kfree(data);
309 	policy->driver_data = NULL;
310 
311 	return 0;
312 }
313 
314 static int qoriq_cpufreq_target(struct cpufreq_policy *policy,
315 		unsigned int index)
316 {
317 	struct clk *parent;
318 	struct cpu_data *data = policy->driver_data;
319 
320 	parent = data->pclk[data->table[index].driver_data];
321 	return clk_set_parent(policy->clk, parent);
322 }
323 
324 static struct cpufreq_driver qoriq_cpufreq_driver = {
325 	.name		= "qoriq_cpufreq",
326 	.flags		= CPUFREQ_CONST_LOOPS,
327 	.init		= qoriq_cpufreq_cpu_init,
328 	.exit		= __exit_p(qoriq_cpufreq_cpu_exit),
329 	.verify		= cpufreq_generic_frequency_table_verify,
330 	.target_index	= qoriq_cpufreq_target,
331 	.get		= cpufreq_generic_get,
332 	.attr		= cpufreq_generic_attr,
333 };
334 
335 static const struct of_device_id node_matches[] __initconst = {
336 	{ .compatible = "fsl,p2041-clockgen", .data = &sdata[0], },
337 	{ .compatible = "fsl,p3041-clockgen", .data = &sdata[0], },
338 	{ .compatible = "fsl,p5020-clockgen", .data = &sdata[1], },
339 	{ .compatible = "fsl,p4080-clockgen", .data = &sdata[2], },
340 	{ .compatible = "fsl,p5040-clockgen", .data = &sdata[2], },
341 	{ .compatible = "fsl,qoriq-clockgen-2.0", },
342 	{}
343 };
344 
345 static int __init qoriq_cpufreq_init(void)
346 {
347 	int ret;
348 	struct device_node  *np;
349 	const struct of_device_id *match;
350 	const struct soc_data *data;
351 
352 	np = of_find_matching_node(NULL, node_matches);
353 	if (!np)
354 		return -ENODEV;
355 
356 	match = of_match_node(node_matches, np);
357 	data = match->data;
358 	if (data) {
359 		if (data->flag)
360 			fmask = data->freq_mask;
361 		min_cpufreq = get_bus_freq();
362 	} else {
363 		min_cpufreq = get_bus_freq() / 2;
364 	}
365 
366 	of_node_put(np);
367 
368 	ret = cpufreq_register_driver(&qoriq_cpufreq_driver);
369 	if (!ret)
370 		pr_info("Freescale QorIQ CPU frequency scaling driver\n");
371 
372 	return ret;
373 }
374 module_init(qoriq_cpufreq_init);
375 
376 static void __exit qoriq_cpufreq_exit(void)
377 {
378 	cpufreq_unregister_driver(&qoriq_cpufreq_driver);
379 }
380 module_exit(qoriq_cpufreq_exit);
381 
382 MODULE_LICENSE("GPL");
383 MODULE_AUTHOR("Tang Yuantian <Yuantian.Tang@freescale.com>");
384 MODULE_DESCRIPTION("cpufreq driver for Freescale QorIQ series SoCs");
385