1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved
4 */
5
6 #include <linux/cpu.h>
7 #include <linux/cpufreq.h>
8 #include <linux/delay.h>
9 #include <linux/dma-mapping.h>
10 #include <linux/module.h>
11 #include <linux/of.h>
12 #include <linux/of_platform.h>
13 #include <linux/platform_device.h>
14 #include <linux/slab.h>
15
16 #include <asm/smp_plat.h>
17
18 #include <soc/tegra/bpmp.h>
19 #include <soc/tegra/bpmp-abi.h>
20
21 #define KHZ 1000
22 #define REF_CLK_MHZ 408 /* 408 MHz */
23 #define US_DELAY 500
24 #define CPUFREQ_TBL_STEP_HZ (50 * KHZ * KHZ)
25 #define MAX_CNT ~0U
26
27 /* cpufreq transisition latency */
28 #define TEGRA_CPUFREQ_TRANSITION_LATENCY (300 * 1000) /* unit in nanoseconds */
29
30 enum cluster {
31 CLUSTER0,
32 CLUSTER1,
33 CLUSTER2,
34 CLUSTER3,
35 MAX_CLUSTERS,
36 };
37
38 struct tegra194_cpufreq_data {
39 void __iomem *regs;
40 size_t num_clusters;
41 struct cpufreq_frequency_table **tables;
42 };
43
44 struct tegra_cpu_ctr {
45 u32 cpu;
46 u32 coreclk_cnt, last_coreclk_cnt;
47 u32 refclk_cnt, last_refclk_cnt;
48 };
49
50 struct read_counters_work {
51 struct work_struct work;
52 struct tegra_cpu_ctr c;
53 };
54
55 static struct workqueue_struct *read_counters_wq;
56
get_cpu_cluster(void * cluster)57 static void get_cpu_cluster(void *cluster)
58 {
59 u64 mpidr = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
60
61 *((uint32_t *)cluster) = MPIDR_AFFINITY_LEVEL(mpidr, 1);
62 }
63
64 /*
65 * Read per-core Read-only system register NVFREQ_FEEDBACK_EL1.
66 * The register provides frequency feedback information to
67 * determine the average actual frequency a core has run at over
68 * a period of time.
69 * [31:0] PLLP counter: Counts at fixed frequency (408 MHz)
70 * [63:32] Core clock counter: counts on every core clock cycle
71 * where the core is architecturally clocking
72 */
read_freq_feedback(void)73 static u64 read_freq_feedback(void)
74 {
75 u64 val = 0;
76
77 asm volatile("mrs %0, s3_0_c15_c0_5" : "=r" (val) : );
78
79 return val;
80 }
81
map_ndiv_to_freq(struct mrq_cpu_ndiv_limits_response * nltbl,u16 ndiv)82 static inline u32 map_ndiv_to_freq(struct mrq_cpu_ndiv_limits_response
83 *nltbl, u16 ndiv)
84 {
85 return nltbl->ref_clk_hz / KHZ * ndiv / (nltbl->pdiv * nltbl->mdiv);
86 }
87
tegra_read_counters(struct work_struct * work)88 static void tegra_read_counters(struct work_struct *work)
89 {
90 struct read_counters_work *read_counters_work;
91 struct tegra_cpu_ctr *c;
92 u64 val;
93
94 /*
95 * ref_clk_counter(32 bit counter) runs on constant clk,
96 * pll_p(408MHz).
97 * It will take = 2 ^ 32 / 408 MHz to overflow ref clk counter
98 * = 10526880 usec = 10.527 sec to overflow
99 *
100 * Like wise core_clk_counter(32 bit counter) runs on core clock.
101 * It's synchronized to crab_clk (cpu_crab_clk) which runs at
102 * freq of cluster. Assuming max cluster clock ~2000MHz,
103 * It will take = 2 ^ 32 / 2000 MHz to overflow core clk counter
104 * = ~2.147 sec to overflow
105 */
106 read_counters_work = container_of(work, struct read_counters_work,
107 work);
108 c = &read_counters_work->c;
109
110 val = read_freq_feedback();
111 c->last_refclk_cnt = lower_32_bits(val);
112 c->last_coreclk_cnt = upper_32_bits(val);
113 udelay(US_DELAY);
114 val = read_freq_feedback();
115 c->refclk_cnt = lower_32_bits(val);
116 c->coreclk_cnt = upper_32_bits(val);
117 }
118
119 /*
120 * Return instantaneous cpu speed
121 * Instantaneous freq is calculated as -
122 * -Takes sample on every query of getting the freq.
123 * - Read core and ref clock counters;
124 * - Delay for X us
125 * - Read above cycle counters again
126 * - Calculates freq by subtracting current and previous counters
127 * divided by the delay time or eqv. of ref_clk_counter in delta time
128 * - Return Kcycles/second, freq in KHz
129 *
130 * delta time period = x sec
131 * = delta ref_clk_counter / (408 * 10^6) sec
132 * freq in Hz = cycles/sec
133 * = (delta cycles / x sec
134 * = (delta cycles * 408 * 10^6) / delta ref_clk_counter
135 * in KHz = (delta cycles * 408 * 10^3) / delta ref_clk_counter
136 *
137 * @cpu - logical cpu whose freq to be updated
138 * Returns freq in KHz on success, 0 if cpu is offline
139 */
tegra194_calculate_speed(u32 cpu)140 static unsigned int tegra194_calculate_speed(u32 cpu)
141 {
142 struct read_counters_work read_counters_work;
143 struct tegra_cpu_ctr c;
144 u32 delta_refcnt;
145 u32 delta_ccnt;
146 u32 rate_mhz;
147
148 /*
149 * udelay() is required to reconstruct cpu frequency over an
150 * observation window. Using workqueue to call udelay() with
151 * interrupts enabled.
152 */
153 read_counters_work.c.cpu = cpu;
154 INIT_WORK_ONSTACK(&read_counters_work.work, tegra_read_counters);
155 queue_work_on(cpu, read_counters_wq, &read_counters_work.work);
156 flush_work(&read_counters_work.work);
157 c = read_counters_work.c;
158
159 if (c.coreclk_cnt < c.last_coreclk_cnt)
160 delta_ccnt = c.coreclk_cnt + (MAX_CNT - c.last_coreclk_cnt);
161 else
162 delta_ccnt = c.coreclk_cnt - c.last_coreclk_cnt;
163 if (!delta_ccnt)
164 return 0;
165
166 /* ref clock is 32 bits */
167 if (c.refclk_cnt < c.last_refclk_cnt)
168 delta_refcnt = c.refclk_cnt + (MAX_CNT - c.last_refclk_cnt);
169 else
170 delta_refcnt = c.refclk_cnt - c.last_refclk_cnt;
171 if (!delta_refcnt) {
172 pr_debug("cpufreq: %d is idle, delta_refcnt: 0\n", cpu);
173 return 0;
174 }
175 rate_mhz = ((unsigned long)(delta_ccnt * REF_CLK_MHZ)) / delta_refcnt;
176
177 return (rate_mhz * KHZ); /* in KHz */
178 }
179
get_cpu_ndiv(void * ndiv)180 static void get_cpu_ndiv(void *ndiv)
181 {
182 u64 ndiv_val;
183
184 asm volatile("mrs %0, s3_0_c15_c0_4" : "=r" (ndiv_val) : );
185
186 *(u64 *)ndiv = ndiv_val;
187 }
188
set_cpu_ndiv(void * data)189 static void set_cpu_ndiv(void *data)
190 {
191 struct cpufreq_frequency_table *tbl = data;
192 u64 ndiv_val = (u64)tbl->driver_data;
193
194 asm volatile("msr s3_0_c15_c0_4, %0" : : "r" (ndiv_val));
195 }
196
tegra194_get_speed(u32 cpu)197 static unsigned int tegra194_get_speed(u32 cpu)
198 {
199 struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
200 struct cpufreq_frequency_table *pos;
201 unsigned int rate;
202 u64 ndiv;
203 int ret;
204 u32 cl;
205
206 smp_call_function_single(cpu, get_cpu_cluster, &cl, true);
207
208 /* reconstruct actual cpu freq using counters */
209 rate = tegra194_calculate_speed(cpu);
210
211 /* get last written ndiv value */
212 ret = smp_call_function_single(cpu, get_cpu_ndiv, &ndiv, true);
213 if (WARN_ON_ONCE(ret))
214 return rate;
215
216 /*
217 * If the reconstructed frequency has acceptable delta from
218 * the last written value, then return freq corresponding
219 * to the last written ndiv value from freq_table. This is
220 * done to return consistent value.
221 */
222 cpufreq_for_each_valid_entry(pos, data->tables[cl]) {
223 if (pos->driver_data != ndiv)
224 continue;
225
226 if (abs(pos->frequency - rate) > 115200) {
227 pr_warn("cpufreq: cpu%d,cur:%u,set:%u,set ndiv:%llu\n",
228 cpu, rate, pos->frequency, ndiv);
229 } else {
230 rate = pos->frequency;
231 }
232 break;
233 }
234 return rate;
235 }
236
tegra194_cpufreq_init(struct cpufreq_policy * policy)237 static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
238 {
239 struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
240 u32 cpu;
241 u32 cl;
242
243 smp_call_function_single(policy->cpu, get_cpu_cluster, &cl, true);
244
245 if (cl >= data->num_clusters)
246 return -EINVAL;
247
248 /* set same policy for all cpus in a cluster */
249 for (cpu = (cl * 2); cpu < ((cl + 1) * 2); cpu++)
250 cpumask_set_cpu(cpu, policy->cpus);
251
252 policy->freq_table = data->tables[cl];
253 policy->cpuinfo.transition_latency = TEGRA_CPUFREQ_TRANSITION_LATENCY;
254
255 return 0;
256 }
257
tegra194_cpufreq_set_target(struct cpufreq_policy * policy,unsigned int index)258 static int tegra194_cpufreq_set_target(struct cpufreq_policy *policy,
259 unsigned int index)
260 {
261 struct cpufreq_frequency_table *tbl = policy->freq_table + index;
262
263 /*
264 * Each core writes frequency in per core register. Then both cores
265 * in a cluster run at same frequency which is the maximum frequency
266 * request out of the values requested by both cores in that cluster.
267 */
268 on_each_cpu_mask(policy->cpus, set_cpu_ndiv, tbl, true);
269
270 return 0;
271 }
272
273 static struct cpufreq_driver tegra194_cpufreq_driver = {
274 .name = "tegra194",
275 .flags = CPUFREQ_CONST_LOOPS | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
276 .verify = cpufreq_generic_frequency_table_verify,
277 .target_index = tegra194_cpufreq_set_target,
278 .get = tegra194_get_speed,
279 .init = tegra194_cpufreq_init,
280 .attr = cpufreq_generic_attr,
281 };
282
tegra194_cpufreq_free_resources(void)283 static void tegra194_cpufreq_free_resources(void)
284 {
285 destroy_workqueue(read_counters_wq);
286 }
287
288 static struct cpufreq_frequency_table *
init_freq_table(struct platform_device * pdev,struct tegra_bpmp * bpmp,unsigned int cluster_id)289 init_freq_table(struct platform_device *pdev, struct tegra_bpmp *bpmp,
290 unsigned int cluster_id)
291 {
292 struct cpufreq_frequency_table *freq_table;
293 struct mrq_cpu_ndiv_limits_response resp;
294 unsigned int num_freqs, ndiv, delta_ndiv;
295 struct mrq_cpu_ndiv_limits_request req;
296 struct tegra_bpmp_message msg;
297 u16 freq_table_step_size;
298 int err, index;
299
300 memset(&req, 0, sizeof(req));
301 req.cluster_id = cluster_id;
302
303 memset(&msg, 0, sizeof(msg));
304 msg.mrq = MRQ_CPU_NDIV_LIMITS;
305 msg.tx.data = &req;
306 msg.tx.size = sizeof(req);
307 msg.rx.data = &resp;
308 msg.rx.size = sizeof(resp);
309
310 err = tegra_bpmp_transfer(bpmp, &msg);
311 if (err)
312 return ERR_PTR(err);
313
314 /*
315 * Make sure frequency table step is a multiple of mdiv to match
316 * vhint table granularity.
317 */
318 freq_table_step_size = resp.mdiv *
319 DIV_ROUND_UP(CPUFREQ_TBL_STEP_HZ, resp.ref_clk_hz);
320
321 dev_dbg(&pdev->dev, "cluster %d: frequency table step size: %d\n",
322 cluster_id, freq_table_step_size);
323
324 delta_ndiv = resp.ndiv_max - resp.ndiv_min;
325
326 if (unlikely(delta_ndiv == 0)) {
327 num_freqs = 1;
328 } else {
329 /* We store both ndiv_min and ndiv_max hence the +1 */
330 num_freqs = delta_ndiv / freq_table_step_size + 1;
331 }
332
333 num_freqs += (delta_ndiv % freq_table_step_size) ? 1 : 0;
334
335 freq_table = devm_kcalloc(&pdev->dev, num_freqs + 1,
336 sizeof(*freq_table), GFP_KERNEL);
337 if (!freq_table)
338 return ERR_PTR(-ENOMEM);
339
340 for (index = 0, ndiv = resp.ndiv_min;
341 ndiv < resp.ndiv_max;
342 index++, ndiv += freq_table_step_size) {
343 freq_table[index].driver_data = ndiv;
344 freq_table[index].frequency = map_ndiv_to_freq(&resp, ndiv);
345 }
346
347 freq_table[index].driver_data = resp.ndiv_max;
348 freq_table[index++].frequency = map_ndiv_to_freq(&resp, resp.ndiv_max);
349 freq_table[index].frequency = CPUFREQ_TABLE_END;
350
351 return freq_table;
352 }
353
tegra194_cpufreq_probe(struct platform_device * pdev)354 static int tegra194_cpufreq_probe(struct platform_device *pdev)
355 {
356 struct tegra194_cpufreq_data *data;
357 struct tegra_bpmp *bpmp;
358 int err, i;
359
360 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
361 if (!data)
362 return -ENOMEM;
363
364 data->num_clusters = MAX_CLUSTERS;
365 data->tables = devm_kcalloc(&pdev->dev, data->num_clusters,
366 sizeof(*data->tables), GFP_KERNEL);
367 if (!data->tables)
368 return -ENOMEM;
369
370 platform_set_drvdata(pdev, data);
371
372 bpmp = tegra_bpmp_get(&pdev->dev);
373 if (IS_ERR(bpmp))
374 return PTR_ERR(bpmp);
375
376 read_counters_wq = alloc_workqueue("read_counters_wq", __WQ_LEGACY, 1);
377 if (!read_counters_wq) {
378 dev_err(&pdev->dev, "fail to create_workqueue\n");
379 err = -EINVAL;
380 goto put_bpmp;
381 }
382
383 for (i = 0; i < data->num_clusters; i++) {
384 data->tables[i] = init_freq_table(pdev, bpmp, i);
385 if (IS_ERR(data->tables[i])) {
386 err = PTR_ERR(data->tables[i]);
387 goto err_free_res;
388 }
389 }
390
391 tegra194_cpufreq_driver.driver_data = data;
392
393 err = cpufreq_register_driver(&tegra194_cpufreq_driver);
394 if (!err)
395 goto put_bpmp;
396
397 err_free_res:
398 tegra194_cpufreq_free_resources();
399 put_bpmp:
400 tegra_bpmp_put(bpmp);
401 return err;
402 }
403
tegra194_cpufreq_remove(struct platform_device * pdev)404 static int tegra194_cpufreq_remove(struct platform_device *pdev)
405 {
406 cpufreq_unregister_driver(&tegra194_cpufreq_driver);
407 tegra194_cpufreq_free_resources();
408
409 return 0;
410 }
411
412 static const struct of_device_id tegra194_cpufreq_of_match[] = {
413 { .compatible = "nvidia,tegra194-ccplex", },
414 { /* sentinel */ }
415 };
416 MODULE_DEVICE_TABLE(of, tegra194_cpufreq_of_match);
417
418 static struct platform_driver tegra194_ccplex_driver = {
419 .driver = {
420 .name = "tegra194-cpufreq",
421 .of_match_table = tegra194_cpufreq_of_match,
422 },
423 .probe = tegra194_cpufreq_probe,
424 .remove = tegra194_cpufreq_remove,
425 };
426 module_platform_driver(tegra194_ccplex_driver);
427
428 MODULE_AUTHOR("Mikko Perttunen <mperttunen@nvidia.com>");
429 MODULE_AUTHOR("Sumit Gupta <sumitg@nvidia.com>");
430 MODULE_DESCRIPTION("NVIDIA Tegra194 cpufreq driver");
431 MODULE_LICENSE("GPL v2");
432