summaryrefslogtreecommitdiff
path: root/drivers/cpufreq/tegra194-cpufreq.c
blob: 6a67f36f3b807b9918bbaf971d7fa2b2d3c49563 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved
 */

#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#include <asm/smp_plat.h>

#include <soc/tegra/bpmp.h>
#include <soc/tegra/bpmp-abi.h>

#define KHZ                     1000
#define REF_CLK_MHZ             408 /* 408 MHz */
#define US_DELAY                500
#define CPUFREQ_TBL_STEP_HZ     (50 * KHZ * KHZ)
#define MAX_CNT                 ~0U

/* cpufreq transisition latency */
#define TEGRA_CPUFREQ_TRANSITION_LATENCY (300 * 1000) /* unit in nanoseconds */

enum cluster {
	CLUSTER0,
	CLUSTER1,
	CLUSTER2,
	CLUSTER3,
	MAX_CLUSTERS,
};

struct tegra194_cpufreq_data {
	void __iomem *regs;
	size_t num_clusters;
	struct cpufreq_frequency_table **tables;
};

struct tegra_cpu_ctr {
	u32 cpu;
	u32 coreclk_cnt, last_coreclk_cnt;
	u32 refclk_cnt, last_refclk_cnt;
};

struct read_counters_work {
	struct work_struct work;
	struct tegra_cpu_ctr c;
};

static struct workqueue_struct *read_counters_wq;

static void get_cpu_cluster(void *cluster)
{
	u64 mpidr = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;

	*((uint32_t *)cluster) = MPIDR_AFFINITY_LEVEL(mpidr, 1);
}

/*
 * Read per-core Read-only system register NVFREQ_FEEDBACK_EL1.
 * The register provides frequency feedback information to
 * determine the average actual frequency a core has run at over
 * a period of time.
 *	[31:0] PLLP counter: Counts at fixed frequency (408 MHz)
 *	[63:32] Core clock counter: counts on every core clock cycle
 *			where the core is architecturally clocking
 */
static u64 read_freq_feedback(void)
{
	u64 val = 0;

	asm volatile("mrs %0, s3_0_c15_c0_5" : "=r" (val) : );

	return val;
}

static inline u32 map_ndiv_to_freq(struct mrq_cpu_ndiv_limits_response
				   *nltbl, u16 ndiv)
{
	return nltbl->ref_clk_hz / KHZ * ndiv / (nltbl->pdiv * nltbl->mdiv);
}

static void tegra_read_counters(struct work_struct *work)
{
	struct read_counters_work *read_counters_work;
	struct tegra_cpu_ctr *c;
	u64 val;

	/*
	 * ref_clk_counter(32 bit counter) runs on constant clk,
	 * pll_p(408MHz).
	 * It will take = 2 ^ 32 / 408 MHz to overflow ref clk counter
	 *              = 10526880 usec = 10.527 sec to overflow
	 *
	 * Like wise core_clk_counter(32 bit counter) runs on core clock.
	 * It's synchronized to crab_clk (cpu_crab_clk) which runs at
	 * freq of cluster. Assuming max cluster clock ~2000MHz,
	 * It will take = 2 ^ 32 / 2000 MHz to overflow core clk counter
	 *              = ~2.147 sec to overflow
	 */
	read_counters_work = container_of(work, struct read_counters_work,
					  work);
	c = &read_counters_work->c;

	val = read_freq_feedback();
	c->last_refclk_cnt = lower_32_bits(val);
	c->last_coreclk_cnt = upper_32_bits(val);
	udelay(US_DELAY);
	val = read_freq_feedback();
	c->refclk_cnt = lower_32_bits(val);
	c->coreclk_cnt = upper_32_bits(val);
}

/*
 * Return instantaneous cpu speed
 * Instantaneous freq is calculated as -
 * -Takes sample on every query of getting the freq.
 *	- Read core and ref clock counters;
 *	- Delay for X us
 *	- Read above cycle counters again
 *	- Calculates freq by subtracting current and previous counters
 *	  divided by the delay time or eqv. of ref_clk_counter in delta time
 *	- Return Kcycles/second, freq in KHz
 *
 *	delta time period = x sec
 *			  = delta ref_clk_counter / (408 * 10^6) sec
 *	freq in Hz = cycles/sec
 *		   = (delta cycles / x sec
 *		   = (delta cycles * 408 * 10^6) / delta ref_clk_counter
 *	in KHz	   = (delta cycles * 408 * 10^3) / delta ref_clk_counter
 *
 * @cpu - logical cpu whose freq to be updated
 * Returns freq in KHz on success, 0 if cpu is offline
 */
static unsigned int tegra194_calculate_speed(u32 cpu)
{
	struct read_counters_work read_counters_work;
	struct tegra_cpu_ctr c;
	u32 delta_refcnt;
	u32 delta_ccnt;
	u32 rate_mhz;

	/*
	 * udelay() is required to reconstruct cpu frequency over an
	 * observation window. Using workqueue to call udelay() with
	 * interrupts enabled.
	 */
	read_counters_work.c.cpu = cpu;
	INIT_WORK_ONSTACK(&read_counters_work.work, tegra_read_counters);
	queue_work_on(cpu, read_counters_wq, &read_counters_work.work);
	flush_work(&read_counters_work.work);
	c = read_counters_work.c;

	if (c.coreclk_cnt < c.last_coreclk_cnt)
		delta_ccnt = c.coreclk_cnt + (MAX_CNT - c.last_coreclk_cnt);
	else
		delta_ccnt = c.coreclk_cnt - c.last_coreclk_cnt;
	if (!delta_ccnt)
		return 0;

	/* ref clock is 32 bits */
	if (c.refclk_cnt < c.last_refclk_cnt)
		delta_refcnt = c.refclk_cnt + (MAX_CNT - c.last_refclk_cnt);
	else
		delta_refcnt = c.refclk_cnt - c.last_refclk_cnt;
	if (!delta_refcnt) {
		pr_debug("cpufreq: %d is idle, delta_refcnt: 0\n", cpu);
		return 0;
	}
	rate_mhz = ((unsigned long)(delta_ccnt * REF_CLK_MHZ)) / delta_refcnt;

	return (rate_mhz * KHZ); /* in KHz */
}

static void get_cpu_ndiv(void *ndiv)
{
	u64 ndiv_val;

	asm volatile("mrs %0, s3_0_c15_c0_4" : "=r" (ndiv_val) : );

	*(u64 *)ndiv = ndiv_val;
}

static void set_cpu_ndiv(void *data)
{
	struct cpufreq_frequency_table *tbl = data;
	u64 ndiv_val = (u64)tbl->driver_data;

	asm volatile("msr s3_0_c15_c0_4, %0" : : "r" (ndiv_val));
}

static unsigned int tegra194_get_speed(u32 cpu)
{
	struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
	struct cpufreq_frequency_table *pos;
	unsigned int rate;
	u64 ndiv;
	int ret;
	u32 cl;

	smp_call_function_single(cpu, get_cpu_cluster, &cl, true);

	/* reconstruct actual cpu freq using counters */
	rate = tegra194_calculate_speed(cpu);

	/* get last written ndiv value */
	ret = smp_call_function_single(cpu, get_cpu_ndiv, &ndiv, true);
	if (WARN_ON_ONCE(ret))
		return rate;

	/*
	 * If the reconstructed frequency has acceptable delta from
	 * the last written value, then return freq corresponding
	 * to the last written ndiv value from freq_table. This is
	 * done to return consistent value.
	 */
	cpufreq_for_each_valid_entry(pos, data->tables[cl]) {
		if (pos->driver_data != ndiv)
			continue;

		if (abs(pos->frequency - rate) > 115200) {
			pr_warn("cpufreq: cpu%d,cur:%u,set:%u,set ndiv:%llu\n",
				cpu, rate, pos->frequency, ndiv);
		} else {
			rate = pos->frequency;
		}
		break;
	}
	return rate;
}

static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
{
	struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
	u32 cpu;
	u32 cl;

	smp_call_function_single(policy->cpu, get_cpu_cluster, &cl, true);

	if (cl >= data->num_clusters)
		return -EINVAL;

	/* set same policy for all cpus in a cluster */
	for (cpu = (cl * 2); cpu < ((cl + 1) * 2); cpu++)
		cpumask_set_cpu(cpu, policy->cpus);

	policy->freq_table = data->tables[cl];
	policy->cpuinfo.transition_latency = TEGRA_CPUFREQ_TRANSITION_LATENCY;

	return 0;
}

static int tegra194_cpufreq_set_target(struct cpufreq_policy *policy,
				       unsigned int index)
{
	struct cpufreq_frequency_table *tbl = policy->freq_table + index;

	/*
	 * Each core writes frequency in per core register. Then both cores
	 * in a cluster run at same frequency which is the maximum frequency
	 * request out of the values requested by both cores in that cluster.
	 */
	on_each_cpu_mask(policy->cpus, set_cpu_ndiv, tbl, true);

	return 0;
}

static struct cpufreq_driver tegra194_cpufreq_driver = {
	.name = "tegra194",
	.flags = CPUFREQ_STICKY | CPUFREQ_CONST_LOOPS |
		CPUFREQ_NEED_INITIAL_FREQ_CHECK,
	.verify = cpufreq_generic_frequency_table_verify,
	.target_index = tegra194_cpufreq_set_target,
	.get = tegra194_get_speed,
	.init = tegra194_cpufreq_init,
	.attr = cpufreq_generic_attr,
};

static void tegra194_cpufreq_free_resources(void)
{
	destroy_workqueue(read_counters_wq);
}

static struct cpufreq_frequency_table *
init_freq_table(struct platform_device *pdev, struct tegra_bpmp *bpmp,
		unsigned int cluster_id)
{
	struct cpufreq_frequency_table *freq_table;
	struct mrq_cpu_ndiv_limits_response resp;
	unsigned int num_freqs, ndiv, delta_ndiv;
	struct mrq_cpu_ndiv_limits_request req;
	struct tegra_bpmp_message msg;
	u16 freq_table_step_size;
	int err, index;

	memset(&req, 0, sizeof(req));
	req.cluster_id = cluster_id;

	memset(&msg, 0, sizeof(msg));
	msg.mrq = MRQ_CPU_NDIV_LIMITS;
	msg.tx.data = &req;
	msg.tx.size = sizeof(req);
	msg.rx.data = &resp;
	msg.rx.size = sizeof(resp);

	err = tegra_bpmp_transfer(bpmp, &msg);
	if (err)
		return ERR_PTR(err);

	/*
	 * Make sure frequency table step is a multiple of mdiv to match
	 * vhint table granularity.
	 */
	freq_table_step_size = resp.mdiv *
			DIV_ROUND_UP(CPUFREQ_TBL_STEP_HZ, resp.ref_clk_hz);

	dev_dbg(&pdev->dev, "cluster %d: frequency table step size: %d\n",
		cluster_id, freq_table_step_size);

	delta_ndiv = resp.ndiv_max - resp.ndiv_min;

	if (unlikely(delta_ndiv == 0)) {
		num_freqs = 1;
	} else {
		/* We store both ndiv_min and ndiv_max hence the +1 */
		num_freqs = delta_ndiv / freq_table_step_size + 1;
	}

	num_freqs += (delta_ndiv % freq_table_step_size) ? 1 : 0;

	freq_table = devm_kcalloc(&pdev->dev, num_freqs + 1,
				  sizeof(*freq_table), GFP_KERNEL);
	if (!freq_table)
		return ERR_PTR(-ENOMEM);

	for (index = 0, ndiv = resp.ndiv_min;
			ndiv < resp.ndiv_max;
			index++, ndiv += freq_table_step_size) {
		freq_table[index].driver_data = ndiv;
		freq_table[index].frequency = map_ndiv_to_freq(&resp, ndiv);
	}

	freq_table[index].driver_data = resp.ndiv_max;
	freq_table[index++].frequency = map_ndiv_to_freq(&resp, resp.ndiv_max);
	freq_table[index].frequency = CPUFREQ_TABLE_END;

	return freq_table;
}

static int tegra194_cpufreq_probe(struct platform_device *pdev)
{
	struct tegra194_cpufreq_data *data;
	struct tegra_bpmp *bpmp;
	int err, i;

	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	data->num_clusters = MAX_CLUSTERS;
	data->tables = devm_kcalloc(&pdev->dev, data->num_clusters,
				    sizeof(*data->tables), GFP_KERNEL);
	if (!data->tables)
		return -ENOMEM;

	platform_set_drvdata(pdev, data);

	bpmp = tegra_bpmp_get(&pdev->dev);
	if (IS_ERR(bpmp))
		return PTR_ERR(bpmp);

	read_counters_wq = alloc_workqueue("read_counters_wq", __WQ_LEGACY, 1);
	if (!read_counters_wq) {
		dev_err(&pdev->dev, "fail to create_workqueue\n");
		err = -EINVAL;
		goto put_bpmp;
	}

	for (i = 0; i < data->num_clusters; i++) {
		data->tables[i] = init_freq_table(pdev, bpmp, i);
		if (IS_ERR(data->tables[i])) {
			err = PTR_ERR(data->tables[i]);
			goto err_free_res;
		}
	}

	tegra194_cpufreq_driver.driver_data = data;

	err = cpufreq_register_driver(&tegra194_cpufreq_driver);
	if (!err)
		goto put_bpmp;

err_free_res:
	tegra194_cpufreq_free_resources();
put_bpmp:
	tegra_bpmp_put(bpmp);
	return err;
}

static int tegra194_cpufreq_remove(struct platform_device *pdev)
{
	cpufreq_unregister_driver(&tegra194_cpufreq_driver);
	tegra194_cpufreq_free_resources();

	return 0;
}

static const struct of_device_id tegra194_cpufreq_of_match[] = {
	{ .compatible = "nvidia,tegra194-ccplex", },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, tegra194_cpufreq_of_match);

static struct platform_driver tegra194_ccplex_driver = {
	.driver = {
		.name = "tegra194-cpufreq",
		.of_match_table = tegra194_cpufreq_of_match,
	},
	.probe = tegra194_cpufreq_probe,
	.remove = tegra194_cpufreq_remove,
};
module_platform_driver(tegra194_ccplex_driver);

MODULE_AUTHOR("Mikko Perttunen <mperttunen@nvidia.com>");
MODULE_AUTHOR("Sumit Gupta <sumitg@nvidia.com>");
MODULE_DESCRIPTION("NVIDIA Tegra194 cpufreq driver");
MODULE_LICENSE("GPL v2");