1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Tegra20 External Memory Controller driver
4  *
5  * Author: Dmitry Osipenko <digetx@gmail.com>
6  */
7 
8 #include <linux/bitfield.h>
9 #include <linux/clk.h>
10 #include <linux/clk/tegra.h>
11 #include <linux/debugfs.h>
12 #include <linux/devfreq.h>
13 #include <linux/err.h>
14 #include <linux/interconnect-provider.h>
15 #include <linux/interrupt.h>
16 #include <linux/io.h>
17 #include <linux/iopoll.h>
18 #include <linux/kernel.h>
19 #include <linux/module.h>
20 #include <linux/mutex.h>
21 #include <linux/of.h>
22 #include <linux/platform_device.h>
23 #include <linux/pm_opp.h>
24 #include <linux/slab.h>
25 #include <linux/sort.h>
26 #include <linux/types.h>
27 
28 #include <soc/tegra/common.h>
29 #include <soc/tegra/fuse.h>
30 
31 #include "../jedec_ddr.h"
32 #include "../of_memory.h"
33 
34 #include "mc.h"
35 
36 #define EMC_INTSTATUS				0x000
37 #define EMC_INTMASK				0x004
38 #define EMC_DBG					0x008
39 #define EMC_ADR_CFG_0				0x010
40 #define EMC_TIMING_CONTROL			0x028
41 #define EMC_RC					0x02c
42 #define EMC_RFC					0x030
43 #define EMC_RAS					0x034
44 #define EMC_RP					0x038
45 #define EMC_R2W					0x03c
46 #define EMC_W2R					0x040
47 #define EMC_R2P					0x044
48 #define EMC_W2P					0x048
49 #define EMC_RD_RCD				0x04c
50 #define EMC_WR_RCD				0x050
51 #define EMC_RRD					0x054
52 #define EMC_REXT				0x058
53 #define EMC_WDV					0x05c
54 #define EMC_QUSE				0x060
55 #define EMC_QRST				0x064
56 #define EMC_QSAFE				0x068
57 #define EMC_RDV					0x06c
58 #define EMC_REFRESH				0x070
59 #define EMC_BURST_REFRESH_NUM			0x074
60 #define EMC_PDEX2WR				0x078
61 #define EMC_PDEX2RD				0x07c
62 #define EMC_PCHG2PDEN				0x080
63 #define EMC_ACT2PDEN				0x084
64 #define EMC_AR2PDEN				0x088
65 #define EMC_RW2PDEN				0x08c
66 #define EMC_TXSR				0x090
67 #define EMC_TCKE				0x094
68 #define EMC_TFAW				0x098
69 #define EMC_TRPAB				0x09c
70 #define EMC_TCLKSTABLE				0x0a0
71 #define EMC_TCLKSTOP				0x0a4
72 #define EMC_TREFBW				0x0a8
73 #define EMC_QUSE_EXTRA				0x0ac
74 #define EMC_ODT_WRITE				0x0b0
75 #define EMC_ODT_READ				0x0b4
76 #define EMC_MRR					0x0ec
77 #define EMC_FBIO_CFG5				0x104
78 #define EMC_FBIO_CFG6				0x114
79 #define EMC_STAT_CONTROL			0x160
80 #define EMC_STAT_LLMC_CONTROL			0x178
81 #define EMC_STAT_PWR_CLOCK_LIMIT		0x198
82 #define EMC_STAT_PWR_CLOCKS			0x19c
83 #define EMC_STAT_PWR_COUNT			0x1a0
84 #define EMC_AUTO_CAL_INTERVAL			0x2a8
85 #define EMC_CFG_2				0x2b8
86 #define EMC_CFG_DIG_DLL				0x2bc
87 #define EMC_DLL_XFORM_DQS			0x2c0
88 #define EMC_DLL_XFORM_QUSE			0x2c4
89 #define EMC_ZCAL_REF_CNT			0x2e0
90 #define EMC_ZCAL_WAIT_CNT			0x2e4
91 #define EMC_CFG_CLKTRIM_0			0x2d0
92 #define EMC_CFG_CLKTRIM_1			0x2d4
93 #define EMC_CFG_CLKTRIM_2			0x2d8
94 
95 #define EMC_CLKCHANGE_REQ_ENABLE		BIT(0)
96 #define EMC_CLKCHANGE_PD_ENABLE			BIT(1)
97 #define EMC_CLKCHANGE_SR_ENABLE			BIT(2)
98 
99 #define EMC_TIMING_UPDATE			BIT(0)
100 
101 #define EMC_REFRESH_OVERFLOW_INT		BIT(3)
102 #define EMC_CLKCHANGE_COMPLETE_INT		BIT(4)
103 #define EMC_MRR_DIVLD_INT			BIT(5)
104 
105 #define EMC_DBG_READ_MUX_ASSEMBLY		BIT(0)
106 #define EMC_DBG_WRITE_MUX_ACTIVE		BIT(1)
107 #define EMC_DBG_FORCE_UPDATE			BIT(2)
108 #define EMC_DBG_READ_DQM_CTRL			BIT(9)
109 #define EMC_DBG_CFG_PRIORITY			BIT(24)
110 
111 #define EMC_FBIO_CFG5_DRAM_WIDTH_X16		BIT(4)
112 #define EMC_FBIO_CFG5_DRAM_TYPE			GENMASK(1, 0)
113 
114 #define EMC_MRR_DEV_SELECTN			GENMASK(31, 30)
115 #define EMC_MRR_MRR_MA				GENMASK(23, 16)
116 #define EMC_MRR_MRR_DATA			GENMASK(15, 0)
117 
118 #define EMC_ADR_CFG_0_EMEM_NUMDEV		GENMASK(25, 24)
119 
120 #define EMC_PWR_GATHER_CLEAR			(1 << 8)
121 #define EMC_PWR_GATHER_DISABLE			(2 << 8)
122 #define EMC_PWR_GATHER_ENABLE			(3 << 8)
123 
124 enum emc_dram_type {
125 	DRAM_TYPE_RESERVED,
126 	DRAM_TYPE_DDR1,
127 	DRAM_TYPE_LPDDR2,
128 	DRAM_TYPE_DDR2,
129 };
130 
131 static const u16 emc_timing_registers[] = {
132 	EMC_RC,
133 	EMC_RFC,
134 	EMC_RAS,
135 	EMC_RP,
136 	EMC_R2W,
137 	EMC_W2R,
138 	EMC_R2P,
139 	EMC_W2P,
140 	EMC_RD_RCD,
141 	EMC_WR_RCD,
142 	EMC_RRD,
143 	EMC_REXT,
144 	EMC_WDV,
145 	EMC_QUSE,
146 	EMC_QRST,
147 	EMC_QSAFE,
148 	EMC_RDV,
149 	EMC_REFRESH,
150 	EMC_BURST_REFRESH_NUM,
151 	EMC_PDEX2WR,
152 	EMC_PDEX2RD,
153 	EMC_PCHG2PDEN,
154 	EMC_ACT2PDEN,
155 	EMC_AR2PDEN,
156 	EMC_RW2PDEN,
157 	EMC_TXSR,
158 	EMC_TCKE,
159 	EMC_TFAW,
160 	EMC_TRPAB,
161 	EMC_TCLKSTABLE,
162 	EMC_TCLKSTOP,
163 	EMC_TREFBW,
164 	EMC_QUSE_EXTRA,
165 	EMC_FBIO_CFG6,
166 	EMC_ODT_WRITE,
167 	EMC_ODT_READ,
168 	EMC_FBIO_CFG5,
169 	EMC_CFG_DIG_DLL,
170 	EMC_DLL_XFORM_DQS,
171 	EMC_DLL_XFORM_QUSE,
172 	EMC_ZCAL_REF_CNT,
173 	EMC_ZCAL_WAIT_CNT,
174 	EMC_AUTO_CAL_INTERVAL,
175 	EMC_CFG_CLKTRIM_0,
176 	EMC_CFG_CLKTRIM_1,
177 	EMC_CFG_CLKTRIM_2,
178 };
179 
180 struct emc_timing {
181 	unsigned long rate;
182 	u32 data[ARRAY_SIZE(emc_timing_registers)];
183 };
184 
185 enum emc_rate_request_type {
186 	EMC_RATE_DEVFREQ,
187 	EMC_RATE_DEBUG,
188 	EMC_RATE_ICC,
189 	EMC_RATE_TYPE_MAX,
190 };
191 
192 struct emc_rate_request {
193 	unsigned long min_rate;
194 	unsigned long max_rate;
195 };
196 
197 struct tegra_emc {
198 	struct device *dev;
199 	struct tegra_mc *mc;
200 	struct icc_provider provider;
201 	struct notifier_block clk_nb;
202 	struct clk *clk;
203 	void __iomem *regs;
204 	unsigned int dram_bus_width;
205 
206 	struct emc_timing *timings;
207 	unsigned int num_timings;
208 
209 	struct {
210 		struct dentry *root;
211 		unsigned long min_rate;
212 		unsigned long max_rate;
213 	} debugfs;
214 
215 	/*
216 	 * There are multiple sources in the EMC driver which could request
217 	 * a min/max clock rate, these rates are contained in this array.
218 	 */
219 	struct emc_rate_request requested_rate[EMC_RATE_TYPE_MAX];
220 
221 	/* protect shared rate-change code path */
222 	struct mutex rate_lock;
223 
224 	struct devfreq_simple_ondemand_data ondemand_data;
225 
226 	/* memory chip identity information */
227 	union lpddr2_basic_config4 basic_conf4;
228 	unsigned int manufacturer_id;
229 	unsigned int revision_id1;
230 	unsigned int revision_id2;
231 
232 	bool mrr_error;
233 };
234 
tegra_emc_isr(int irq,void * data)235 static irqreturn_t tegra_emc_isr(int irq, void *data)
236 {
237 	struct tegra_emc *emc = data;
238 	u32 intmask = EMC_REFRESH_OVERFLOW_INT;
239 	u32 status;
240 
241 	status = readl_relaxed(emc->regs + EMC_INTSTATUS) & intmask;
242 	if (!status)
243 		return IRQ_NONE;
244 
245 	/* notify about HW problem */
246 	if (status & EMC_REFRESH_OVERFLOW_INT)
247 		dev_err_ratelimited(emc->dev,
248 				    "refresh request overflow timeout\n");
249 
250 	/* clear interrupts */
251 	writel_relaxed(status, emc->regs + EMC_INTSTATUS);
252 
253 	return IRQ_HANDLED;
254 }
255 
tegra_emc_find_timing(struct tegra_emc * emc,unsigned long rate)256 static struct emc_timing *tegra_emc_find_timing(struct tegra_emc *emc,
257 						unsigned long rate)
258 {
259 	struct emc_timing *timing = NULL;
260 	unsigned int i;
261 
262 	for (i = 0; i < emc->num_timings; i++) {
263 		if (emc->timings[i].rate >= rate) {
264 			timing = &emc->timings[i];
265 			break;
266 		}
267 	}
268 
269 	if (!timing) {
270 		dev_err(emc->dev, "no timing for rate %lu\n", rate);
271 		return NULL;
272 	}
273 
274 	return timing;
275 }
276 
emc_prepare_timing_change(struct tegra_emc * emc,unsigned long rate)277 static int emc_prepare_timing_change(struct tegra_emc *emc, unsigned long rate)
278 {
279 	struct emc_timing *timing = tegra_emc_find_timing(emc, rate);
280 	unsigned int i;
281 
282 	if (!timing)
283 		return -EINVAL;
284 
285 	dev_dbg(emc->dev, "%s: using timing rate %lu for requested rate %lu\n",
286 		__func__, timing->rate, rate);
287 
288 	/* program shadow registers */
289 	for (i = 0; i < ARRAY_SIZE(timing->data); i++)
290 		writel_relaxed(timing->data[i],
291 			       emc->regs + emc_timing_registers[i]);
292 
293 	/* wait until programming has settled */
294 	readl_relaxed(emc->regs + emc_timing_registers[i - 1]);
295 
296 	return 0;
297 }
298 
emc_complete_timing_change(struct tegra_emc * emc,bool flush)299 static int emc_complete_timing_change(struct tegra_emc *emc, bool flush)
300 {
301 	int err;
302 	u32 v;
303 
304 	dev_dbg(emc->dev, "%s: flush %d\n", __func__, flush);
305 
306 	if (flush) {
307 		/* manually initiate memory timing update */
308 		writel_relaxed(EMC_TIMING_UPDATE,
309 			       emc->regs + EMC_TIMING_CONTROL);
310 		return 0;
311 	}
312 
313 	err = readl_relaxed_poll_timeout_atomic(emc->regs + EMC_INTSTATUS, v,
314 						v & EMC_CLKCHANGE_COMPLETE_INT,
315 						1, 100);
316 	if (err) {
317 		dev_err(emc->dev, "emc-car handshake timeout: %d\n", err);
318 		return err;
319 	}
320 
321 	return 0;
322 }
323 
tegra_emc_clk_change_notify(struct notifier_block * nb,unsigned long msg,void * data)324 static int tegra_emc_clk_change_notify(struct notifier_block *nb,
325 				       unsigned long msg, void *data)
326 {
327 	struct tegra_emc *emc = container_of(nb, struct tegra_emc, clk_nb);
328 	struct clk_notifier_data *cnd = data;
329 	int err;
330 
331 	switch (msg) {
332 	case PRE_RATE_CHANGE:
333 		err = emc_prepare_timing_change(emc, cnd->new_rate);
334 		break;
335 
336 	case ABORT_RATE_CHANGE:
337 		err = emc_prepare_timing_change(emc, cnd->old_rate);
338 		if (err)
339 			break;
340 
341 		err = emc_complete_timing_change(emc, true);
342 		break;
343 
344 	case POST_RATE_CHANGE:
345 		err = emc_complete_timing_change(emc, false);
346 		break;
347 
348 	default:
349 		return NOTIFY_DONE;
350 	}
351 
352 	return notifier_from_errno(err);
353 }
354 
load_one_timing_from_dt(struct tegra_emc * emc,struct emc_timing * timing,struct device_node * node)355 static int load_one_timing_from_dt(struct tegra_emc *emc,
356 				   struct emc_timing *timing,
357 				   struct device_node *node)
358 {
359 	u32 rate;
360 	int err;
361 
362 	if (!of_device_is_compatible(node, "nvidia,tegra20-emc-table")) {
363 		dev_err(emc->dev, "incompatible DT node: %pOF\n", node);
364 		return -EINVAL;
365 	}
366 
367 	err = of_property_read_u32(node, "clock-frequency", &rate);
368 	if (err) {
369 		dev_err(emc->dev, "timing %pOF: failed to read rate: %d\n",
370 			node, err);
371 		return err;
372 	}
373 
374 	err = of_property_read_u32_array(node, "nvidia,emc-registers",
375 					 timing->data,
376 					 ARRAY_SIZE(emc_timing_registers));
377 	if (err) {
378 		dev_err(emc->dev,
379 			"timing %pOF: failed to read emc timing data: %d\n",
380 			node, err);
381 		return err;
382 	}
383 
384 	/*
385 	 * The EMC clock rate is twice the bus rate, and the bus rate is
386 	 * measured in kHz.
387 	 */
388 	timing->rate = rate * 2 * 1000;
389 
390 	dev_dbg(emc->dev, "%s: %pOF: EMC rate %lu\n",
391 		__func__, node, timing->rate);
392 
393 	return 0;
394 }
395 
cmp_timings(const void * _a,const void * _b)396 static int cmp_timings(const void *_a, const void *_b)
397 {
398 	const struct emc_timing *a = _a;
399 	const struct emc_timing *b = _b;
400 
401 	if (a->rate < b->rate)
402 		return -1;
403 
404 	if (a->rate > b->rate)
405 		return 1;
406 
407 	return 0;
408 }
409 
tegra_emc_load_timings_from_dt(struct tegra_emc * emc,struct device_node * node)410 static int tegra_emc_load_timings_from_dt(struct tegra_emc *emc,
411 					  struct device_node *node)
412 {
413 	struct device_node *child;
414 	struct emc_timing *timing;
415 	int child_count;
416 	int err;
417 
418 	child_count = of_get_child_count(node);
419 	if (!child_count) {
420 		dev_err(emc->dev, "no memory timings in DT node: %pOF\n", node);
421 		return -EINVAL;
422 	}
423 
424 	emc->timings = devm_kcalloc(emc->dev, child_count, sizeof(*timing),
425 				    GFP_KERNEL);
426 	if (!emc->timings)
427 		return -ENOMEM;
428 
429 	timing = emc->timings;
430 
431 	for_each_child_of_node(node, child) {
432 		if (of_node_name_eq(child, "lpddr2"))
433 			continue;
434 
435 		err = load_one_timing_from_dt(emc, timing++, child);
436 		if (err) {
437 			of_node_put(child);
438 			return err;
439 		}
440 
441 		emc->num_timings++;
442 	}
443 
444 	sort(emc->timings, emc->num_timings, sizeof(*timing), cmp_timings,
445 	     NULL);
446 
447 	dev_info_once(emc->dev,
448 		      "got %u timings for RAM code %u (min %luMHz max %luMHz)\n",
449 		      emc->num_timings,
450 		      tegra_read_ram_code(),
451 		      emc->timings[0].rate / 1000000,
452 		      emc->timings[emc->num_timings - 1].rate / 1000000);
453 
454 	return 0;
455 }
456 
457 static struct device_node *
tegra_emc_find_node_by_ram_code(struct tegra_emc * emc)458 tegra_emc_find_node_by_ram_code(struct tegra_emc *emc)
459 {
460 	struct device *dev = emc->dev;
461 	struct device_node *np;
462 	u32 value, ram_code;
463 	int err;
464 
465 	if (emc->mrr_error) {
466 		dev_warn(dev, "memory timings skipped due to MRR error\n");
467 		return NULL;
468 	}
469 
470 	if (of_get_child_count(dev->of_node) == 0) {
471 		dev_info_once(dev, "device-tree doesn't have memory timings\n");
472 		return NULL;
473 	}
474 
475 	if (!of_property_read_bool(dev->of_node, "nvidia,use-ram-code"))
476 		return of_node_get(dev->of_node);
477 
478 	ram_code = tegra_read_ram_code();
479 
480 	for (np = of_find_node_by_name(dev->of_node, "emc-tables"); np;
481 	     np = of_find_node_by_name(np, "emc-tables")) {
482 		err = of_property_read_u32(np, "nvidia,ram-code", &value);
483 		if (err || value != ram_code) {
484 			struct device_node *lpddr2_np;
485 			bool cfg_mismatches = false;
486 
487 			lpddr2_np = of_find_node_by_name(np, "lpddr2");
488 			if (lpddr2_np) {
489 				const struct lpddr2_info *info;
490 
491 				info = of_lpddr2_get_info(lpddr2_np, dev);
492 				if (info) {
493 					if (info->manufacturer_id >= 0 &&
494 					    info->manufacturer_id != emc->manufacturer_id)
495 						cfg_mismatches = true;
496 
497 					if (info->revision_id1 >= 0 &&
498 					    info->revision_id1 != emc->revision_id1)
499 						cfg_mismatches = true;
500 
501 					if (info->revision_id2 >= 0 &&
502 					    info->revision_id2 != emc->revision_id2)
503 						cfg_mismatches = true;
504 
505 					if (info->density != emc->basic_conf4.density)
506 						cfg_mismatches = true;
507 
508 					if (info->io_width != emc->basic_conf4.io_width)
509 						cfg_mismatches = true;
510 
511 					if (info->arch_type != emc->basic_conf4.arch_type)
512 						cfg_mismatches = true;
513 				} else {
514 					dev_err(dev, "failed to parse %pOF\n", lpddr2_np);
515 					cfg_mismatches = true;
516 				}
517 
518 				of_node_put(lpddr2_np);
519 			} else {
520 				cfg_mismatches = true;
521 			}
522 
523 			if (cfg_mismatches) {
524 				of_node_put(np);
525 				continue;
526 			}
527 		}
528 
529 		return np;
530 	}
531 
532 	dev_err(dev, "no memory timings for RAM code %u found in device tree\n",
533 		ram_code);
534 
535 	return NULL;
536 }
537 
emc_read_lpddr_mode_register(struct tegra_emc * emc,unsigned int emem_dev,unsigned int register_addr,unsigned int * register_data)538 static int emc_read_lpddr_mode_register(struct tegra_emc *emc,
539 					unsigned int emem_dev,
540 					unsigned int register_addr,
541 					unsigned int *register_data)
542 {
543 	u32 memory_dev = emem_dev ? 1 : 2;
544 	u32 val, mr_mask = 0xff;
545 	int err;
546 
547 	/* clear data-valid interrupt status */
548 	writel_relaxed(EMC_MRR_DIVLD_INT, emc->regs + EMC_INTSTATUS);
549 
550 	/* issue mode register read request */
551 	val  = FIELD_PREP(EMC_MRR_DEV_SELECTN, memory_dev);
552 	val |= FIELD_PREP(EMC_MRR_MRR_MA, register_addr);
553 
554 	writel_relaxed(val, emc->regs + EMC_MRR);
555 
556 	/* wait for the LPDDR2 data-valid interrupt */
557 	err = readl_relaxed_poll_timeout_atomic(emc->regs + EMC_INTSTATUS, val,
558 						val & EMC_MRR_DIVLD_INT,
559 						1, 100);
560 	if (err) {
561 		dev_err(emc->dev, "mode register %u read failed: %d\n",
562 			register_addr, err);
563 		emc->mrr_error = true;
564 		return err;
565 	}
566 
567 	/* read out mode register data */
568 	val = readl_relaxed(emc->regs + EMC_MRR);
569 	*register_data = FIELD_GET(EMC_MRR_MRR_DATA, val) & mr_mask;
570 
571 	return 0;
572 }
573 
emc_read_lpddr_sdram_info(struct tegra_emc * emc,unsigned int emem_dev,bool print_out)574 static void emc_read_lpddr_sdram_info(struct tegra_emc *emc,
575 				      unsigned int emem_dev,
576 				      bool print_out)
577 {
578 	/* these registers are standard for all LPDDR JEDEC memory chips */
579 	emc_read_lpddr_mode_register(emc, emem_dev, 5, &emc->manufacturer_id);
580 	emc_read_lpddr_mode_register(emc, emem_dev, 6, &emc->revision_id1);
581 	emc_read_lpddr_mode_register(emc, emem_dev, 7, &emc->revision_id2);
582 	emc_read_lpddr_mode_register(emc, emem_dev, 8, &emc->basic_conf4.value);
583 
584 	if (!print_out)
585 		return;
586 
587 	dev_info(emc->dev, "SDRAM[dev%u]: manufacturer: 0x%x (%s) rev1: 0x%x rev2: 0x%x prefetch: S%u density: %uMbit iowidth: %ubit\n",
588 		 emem_dev, emc->manufacturer_id,
589 		 lpddr2_jedec_manufacturer(emc->manufacturer_id),
590 		 emc->revision_id1, emc->revision_id2,
591 		 4 >> emc->basic_conf4.arch_type,
592 		 64 << emc->basic_conf4.density,
593 		 32 >> emc->basic_conf4.io_width);
594 }
595 
emc_setup_hw(struct tegra_emc * emc)596 static int emc_setup_hw(struct tegra_emc *emc)
597 {
598 	u32 emc_cfg, emc_dbg, emc_fbio, emc_adr_cfg;
599 	u32 intmask = EMC_REFRESH_OVERFLOW_INT;
600 	static bool print_sdram_info_once;
601 	enum emc_dram_type dram_type;
602 	const char *dram_type_str;
603 	unsigned int emem_numdev;
604 
605 	emc_cfg = readl_relaxed(emc->regs + EMC_CFG_2);
606 
607 	/*
608 	 * Depending on a memory type, DRAM should enter either self-refresh
609 	 * or power-down state on EMC clock change.
610 	 */
611 	if (!(emc_cfg & EMC_CLKCHANGE_PD_ENABLE) &&
612 	    !(emc_cfg & EMC_CLKCHANGE_SR_ENABLE)) {
613 		dev_err(emc->dev,
614 			"bootloader didn't specify DRAM auto-suspend mode\n");
615 		return -EINVAL;
616 	}
617 
618 	/* enable EMC and CAR to handshake on PLL divider/source changes */
619 	emc_cfg |= EMC_CLKCHANGE_REQ_ENABLE;
620 	writel_relaxed(emc_cfg, emc->regs + EMC_CFG_2);
621 
622 	/* initialize interrupt */
623 	writel_relaxed(intmask, emc->regs + EMC_INTMASK);
624 	writel_relaxed(intmask, emc->regs + EMC_INTSTATUS);
625 
626 	/* ensure that unwanted debug features are disabled */
627 	emc_dbg = readl_relaxed(emc->regs + EMC_DBG);
628 	emc_dbg |= EMC_DBG_CFG_PRIORITY;
629 	emc_dbg &= ~EMC_DBG_READ_MUX_ASSEMBLY;
630 	emc_dbg &= ~EMC_DBG_WRITE_MUX_ACTIVE;
631 	emc_dbg &= ~EMC_DBG_FORCE_UPDATE;
632 	writel_relaxed(emc_dbg, emc->regs + EMC_DBG);
633 
634 	emc_fbio = readl_relaxed(emc->regs + EMC_FBIO_CFG5);
635 
636 	if (emc_fbio & EMC_FBIO_CFG5_DRAM_WIDTH_X16)
637 		emc->dram_bus_width = 16;
638 	else
639 		emc->dram_bus_width = 32;
640 
641 	dram_type = FIELD_GET(EMC_FBIO_CFG5_DRAM_TYPE, emc_fbio);
642 
643 	switch (dram_type) {
644 	case DRAM_TYPE_RESERVED:
645 		dram_type_str = "INVALID";
646 		break;
647 	case DRAM_TYPE_DDR1:
648 		dram_type_str = "DDR1";
649 		break;
650 	case DRAM_TYPE_LPDDR2:
651 		dram_type_str = "LPDDR2";
652 		break;
653 	case DRAM_TYPE_DDR2:
654 		dram_type_str = "DDR2";
655 		break;
656 	}
657 
658 	emc_adr_cfg = readl_relaxed(emc->regs + EMC_ADR_CFG_0);
659 	emem_numdev = FIELD_GET(EMC_ADR_CFG_0_EMEM_NUMDEV, emc_adr_cfg) + 1;
660 
661 	dev_info_once(emc->dev, "%ubit DRAM bus, %u %s %s attached\n",
662 		      emc->dram_bus_width, emem_numdev, dram_type_str,
663 		      emem_numdev == 2 ? "devices" : "device");
664 
665 	if (dram_type == DRAM_TYPE_LPDDR2) {
666 		while (emem_numdev--)
667 			emc_read_lpddr_sdram_info(emc, emem_numdev,
668 						  !print_sdram_info_once);
669 		print_sdram_info_once = true;
670 	}
671 
672 	return 0;
673 }
674 
emc_round_rate(unsigned long rate,unsigned long min_rate,unsigned long max_rate,void * arg)675 static long emc_round_rate(unsigned long rate,
676 			   unsigned long min_rate,
677 			   unsigned long max_rate,
678 			   void *arg)
679 {
680 	struct emc_timing *timing = NULL;
681 	struct tegra_emc *emc = arg;
682 	unsigned int i;
683 
684 	if (!emc->num_timings)
685 		return clk_get_rate(emc->clk);
686 
687 	min_rate = min(min_rate, emc->timings[emc->num_timings - 1].rate);
688 
689 	for (i = 0; i < emc->num_timings; i++) {
690 		if (emc->timings[i].rate < rate && i != emc->num_timings - 1)
691 			continue;
692 
693 		if (emc->timings[i].rate > max_rate) {
694 			i = max(i, 1u) - 1;
695 
696 			if (emc->timings[i].rate < min_rate)
697 				break;
698 		}
699 
700 		if (emc->timings[i].rate < min_rate)
701 			continue;
702 
703 		timing = &emc->timings[i];
704 		break;
705 	}
706 
707 	if (!timing) {
708 		dev_err(emc->dev, "no timing for rate %lu min %lu max %lu\n",
709 			rate, min_rate, max_rate);
710 		return -EINVAL;
711 	}
712 
713 	return timing->rate;
714 }
715 
tegra_emc_rate_requests_init(struct tegra_emc * emc)716 static void tegra_emc_rate_requests_init(struct tegra_emc *emc)
717 {
718 	unsigned int i;
719 
720 	for (i = 0; i < EMC_RATE_TYPE_MAX; i++) {
721 		emc->requested_rate[i].min_rate = 0;
722 		emc->requested_rate[i].max_rate = ULONG_MAX;
723 	}
724 }
725 
emc_request_rate(struct tegra_emc * emc,unsigned long new_min_rate,unsigned long new_max_rate,enum emc_rate_request_type type)726 static int emc_request_rate(struct tegra_emc *emc,
727 			    unsigned long new_min_rate,
728 			    unsigned long new_max_rate,
729 			    enum emc_rate_request_type type)
730 {
731 	struct emc_rate_request *req = emc->requested_rate;
732 	unsigned long min_rate = 0, max_rate = ULONG_MAX;
733 	unsigned int i;
734 	int err;
735 
736 	/* select minimum and maximum rates among the requested rates */
737 	for (i = 0; i < EMC_RATE_TYPE_MAX; i++, req++) {
738 		if (i == type) {
739 			min_rate = max(new_min_rate, min_rate);
740 			max_rate = min(new_max_rate, max_rate);
741 		} else {
742 			min_rate = max(req->min_rate, min_rate);
743 			max_rate = min(req->max_rate, max_rate);
744 		}
745 	}
746 
747 	if (min_rate > max_rate) {
748 		dev_err_ratelimited(emc->dev, "%s: type %u: out of range: %lu %lu\n",
749 				    __func__, type, min_rate, max_rate);
750 		return -ERANGE;
751 	}
752 
753 	/*
754 	 * EMC rate-changes should go via OPP API because it manages voltage
755 	 * changes.
756 	 */
757 	err = dev_pm_opp_set_rate(emc->dev, min_rate);
758 	if (err)
759 		return err;
760 
761 	emc->requested_rate[type].min_rate = new_min_rate;
762 	emc->requested_rate[type].max_rate = new_max_rate;
763 
764 	return 0;
765 }
766 
emc_set_min_rate(struct tegra_emc * emc,unsigned long rate,enum emc_rate_request_type type)767 static int emc_set_min_rate(struct tegra_emc *emc, unsigned long rate,
768 			    enum emc_rate_request_type type)
769 {
770 	struct emc_rate_request *req = &emc->requested_rate[type];
771 	int ret;
772 
773 	mutex_lock(&emc->rate_lock);
774 	ret = emc_request_rate(emc, rate, req->max_rate, type);
775 	mutex_unlock(&emc->rate_lock);
776 
777 	return ret;
778 }
779 
emc_set_max_rate(struct tegra_emc * emc,unsigned long rate,enum emc_rate_request_type type)780 static int emc_set_max_rate(struct tegra_emc *emc, unsigned long rate,
781 			    enum emc_rate_request_type type)
782 {
783 	struct emc_rate_request *req = &emc->requested_rate[type];
784 	int ret;
785 
786 	mutex_lock(&emc->rate_lock);
787 	ret = emc_request_rate(emc, req->min_rate, rate, type);
788 	mutex_unlock(&emc->rate_lock);
789 
790 	return ret;
791 }
792 
793 /*
794  * debugfs interface
795  *
796  * The memory controller driver exposes some files in debugfs that can be used
797  * to control the EMC frequency. The top-level directory can be found here:
798  *
799  *   /sys/kernel/debug/emc
800  *
801  * It contains the following files:
802  *
803  *   - available_rates: This file contains a list of valid, space-separated
804  *     EMC frequencies.
805  *
806  *   - min_rate: Writing a value to this file sets the given frequency as the
807  *       floor of the permitted range. If this is higher than the currently
808  *       configured EMC frequency, this will cause the frequency to be
809  *       increased so that it stays within the valid range.
810  *
811  *   - max_rate: Similarily to the min_rate file, writing a value to this file
812  *       sets the given frequency as the ceiling of the permitted range. If
813  *       the value is lower than the currently configured EMC frequency, this
814  *       will cause the frequency to be decreased so that it stays within the
815  *       valid range.
816  */
817 
tegra_emc_validate_rate(struct tegra_emc * emc,unsigned long rate)818 static bool tegra_emc_validate_rate(struct tegra_emc *emc, unsigned long rate)
819 {
820 	unsigned int i;
821 
822 	for (i = 0; i < emc->num_timings; i++)
823 		if (rate == emc->timings[i].rate)
824 			return true;
825 
826 	return false;
827 }
828 
tegra_emc_debug_available_rates_show(struct seq_file * s,void * data)829 static int tegra_emc_debug_available_rates_show(struct seq_file *s, void *data)
830 {
831 	struct tegra_emc *emc = s->private;
832 	const char *prefix = "";
833 	unsigned int i;
834 
835 	for (i = 0; i < emc->num_timings; i++) {
836 		seq_printf(s, "%s%lu", prefix, emc->timings[i].rate);
837 		prefix = " ";
838 	}
839 
840 	seq_puts(s, "\n");
841 
842 	return 0;
843 }
844 DEFINE_SHOW_ATTRIBUTE(tegra_emc_debug_available_rates);
845 
tegra_emc_debug_min_rate_get(void * data,u64 * rate)846 static int tegra_emc_debug_min_rate_get(void *data, u64 *rate)
847 {
848 	struct tegra_emc *emc = data;
849 
850 	*rate = emc->debugfs.min_rate;
851 
852 	return 0;
853 }
854 
tegra_emc_debug_min_rate_set(void * data,u64 rate)855 static int tegra_emc_debug_min_rate_set(void *data, u64 rate)
856 {
857 	struct tegra_emc *emc = data;
858 	int err;
859 
860 	if (!tegra_emc_validate_rate(emc, rate))
861 		return -EINVAL;
862 
863 	err = emc_set_min_rate(emc, rate, EMC_RATE_DEBUG);
864 	if (err < 0)
865 		return err;
866 
867 	emc->debugfs.min_rate = rate;
868 
869 	return 0;
870 }
871 
872 DEFINE_SIMPLE_ATTRIBUTE(tegra_emc_debug_min_rate_fops,
873 			tegra_emc_debug_min_rate_get,
874 			tegra_emc_debug_min_rate_set, "%llu\n");
875 
tegra_emc_debug_max_rate_get(void * data,u64 * rate)876 static int tegra_emc_debug_max_rate_get(void *data, u64 *rate)
877 {
878 	struct tegra_emc *emc = data;
879 
880 	*rate = emc->debugfs.max_rate;
881 
882 	return 0;
883 }
884 
tegra_emc_debug_max_rate_set(void * data,u64 rate)885 static int tegra_emc_debug_max_rate_set(void *data, u64 rate)
886 {
887 	struct tegra_emc *emc = data;
888 	int err;
889 
890 	if (!tegra_emc_validate_rate(emc, rate))
891 		return -EINVAL;
892 
893 	err = emc_set_max_rate(emc, rate, EMC_RATE_DEBUG);
894 	if (err < 0)
895 		return err;
896 
897 	emc->debugfs.max_rate = rate;
898 
899 	return 0;
900 }
901 
902 DEFINE_SIMPLE_ATTRIBUTE(tegra_emc_debug_max_rate_fops,
903 			tegra_emc_debug_max_rate_get,
904 			tegra_emc_debug_max_rate_set, "%llu\n");
905 
tegra_emc_debugfs_init(struct tegra_emc * emc)906 static void tegra_emc_debugfs_init(struct tegra_emc *emc)
907 {
908 	struct device *dev = emc->dev;
909 	unsigned int i;
910 	int err;
911 
912 	emc->debugfs.min_rate = ULONG_MAX;
913 	emc->debugfs.max_rate = 0;
914 
915 	for (i = 0; i < emc->num_timings; i++) {
916 		if (emc->timings[i].rate < emc->debugfs.min_rate)
917 			emc->debugfs.min_rate = emc->timings[i].rate;
918 
919 		if (emc->timings[i].rate > emc->debugfs.max_rate)
920 			emc->debugfs.max_rate = emc->timings[i].rate;
921 	}
922 
923 	if (!emc->num_timings) {
924 		emc->debugfs.min_rate = clk_get_rate(emc->clk);
925 		emc->debugfs.max_rate = emc->debugfs.min_rate;
926 	}
927 
928 	err = clk_set_rate_range(emc->clk, emc->debugfs.min_rate,
929 				 emc->debugfs.max_rate);
930 	if (err < 0) {
931 		dev_err(dev, "failed to set rate range [%lu-%lu] for %pC\n",
932 			emc->debugfs.min_rate, emc->debugfs.max_rate,
933 			emc->clk);
934 	}
935 
936 	emc->debugfs.root = debugfs_create_dir("emc", NULL);
937 
938 	debugfs_create_file("available_rates", 0444, emc->debugfs.root,
939 			    emc, &tegra_emc_debug_available_rates_fops);
940 	debugfs_create_file("min_rate", 0644, emc->debugfs.root,
941 			    emc, &tegra_emc_debug_min_rate_fops);
942 	debugfs_create_file("max_rate", 0644, emc->debugfs.root,
943 			    emc, &tegra_emc_debug_max_rate_fops);
944 }
945 
946 static inline struct tegra_emc *
to_tegra_emc_provider(struct icc_provider * provider)947 to_tegra_emc_provider(struct icc_provider *provider)
948 {
949 	return container_of(provider, struct tegra_emc, provider);
950 }
951 
952 static struct icc_node_data *
emc_of_icc_xlate_extended(struct of_phandle_args * spec,void * data)953 emc_of_icc_xlate_extended(struct of_phandle_args *spec, void *data)
954 {
955 	struct icc_provider *provider = data;
956 	struct icc_node_data *ndata;
957 	struct icc_node *node;
958 
959 	/* External Memory is the only possible ICC route */
960 	list_for_each_entry(node, &provider->nodes, node_list) {
961 		if (node->id != TEGRA_ICC_EMEM)
962 			continue;
963 
964 		ndata = kzalloc(sizeof(*ndata), GFP_KERNEL);
965 		if (!ndata)
966 			return ERR_PTR(-ENOMEM);
967 
968 		/*
969 		 * SRC and DST nodes should have matching TAG in order to have
970 		 * it set by default for a requested path.
971 		 */
972 		ndata->tag = TEGRA_MC_ICC_TAG_ISO;
973 		ndata->node = node;
974 
975 		return ndata;
976 	}
977 
978 	return ERR_PTR(-EPROBE_DEFER);
979 }
980 
emc_icc_set(struct icc_node * src,struct icc_node * dst)981 static int emc_icc_set(struct icc_node *src, struct icc_node *dst)
982 {
983 	struct tegra_emc *emc = to_tegra_emc_provider(dst->provider);
984 	unsigned long long peak_bw = icc_units_to_bps(dst->peak_bw);
985 	unsigned long long avg_bw = icc_units_to_bps(dst->avg_bw);
986 	unsigned long long rate = max(avg_bw, peak_bw);
987 	unsigned int dram_data_bus_width_bytes;
988 	int err;
989 
990 	/*
991 	 * Tegra20 EMC runs on x2 clock rate of SDRAM bus because DDR data
992 	 * is sampled on both clock edges.  This means that EMC clock rate
993 	 * equals to the peak data-rate.
994 	 */
995 	dram_data_bus_width_bytes = emc->dram_bus_width / 8;
996 	do_div(rate, dram_data_bus_width_bytes);
997 	rate = min_t(u64, rate, U32_MAX);
998 
999 	err = emc_set_min_rate(emc, rate, EMC_RATE_ICC);
1000 	if (err)
1001 		return err;
1002 
1003 	return 0;
1004 }
1005 
tegra_emc_interconnect_init(struct tegra_emc * emc)1006 static int tegra_emc_interconnect_init(struct tegra_emc *emc)
1007 {
1008 	const struct tegra_mc_soc *soc;
1009 	struct icc_node *node;
1010 	int err;
1011 
1012 	emc->mc = devm_tegra_memory_controller_get(emc->dev);
1013 	if (IS_ERR(emc->mc))
1014 		return PTR_ERR(emc->mc);
1015 
1016 	soc = emc->mc->soc;
1017 
1018 	emc->provider.dev = emc->dev;
1019 	emc->provider.set = emc_icc_set;
1020 	emc->provider.data = &emc->provider;
1021 	emc->provider.aggregate = soc->icc_ops->aggregate;
1022 	emc->provider.xlate_extended = emc_of_icc_xlate_extended;
1023 
1024 	icc_provider_init(&emc->provider);
1025 
1026 	/* create External Memory Controller node */
1027 	node = icc_node_create(TEGRA_ICC_EMC);
1028 	if (IS_ERR(node)) {
1029 		err = PTR_ERR(node);
1030 		goto err_msg;
1031 	}
1032 
1033 	node->name = "External Memory Controller";
1034 	icc_node_add(node, &emc->provider);
1035 
1036 	/* link External Memory Controller to External Memory (DRAM) */
1037 	err = icc_link_create(node, TEGRA_ICC_EMEM);
1038 	if (err)
1039 		goto remove_nodes;
1040 
1041 	/* create External Memory node */
1042 	node = icc_node_create(TEGRA_ICC_EMEM);
1043 	if (IS_ERR(node)) {
1044 		err = PTR_ERR(node);
1045 		goto remove_nodes;
1046 	}
1047 
1048 	node->name = "External Memory (DRAM)";
1049 	icc_node_add(node, &emc->provider);
1050 
1051 	err = icc_provider_register(&emc->provider);
1052 	if (err)
1053 		goto remove_nodes;
1054 
1055 	return 0;
1056 
1057 remove_nodes:
1058 	icc_nodes_remove(&emc->provider);
1059 err_msg:
1060 	dev_err(emc->dev, "failed to initialize ICC: %d\n", err);
1061 
1062 	return err;
1063 }
1064 
devm_tegra_emc_unset_callback(void * data)1065 static void devm_tegra_emc_unset_callback(void *data)
1066 {
1067 	tegra20_clk_set_emc_round_callback(NULL, NULL);
1068 }
1069 
devm_tegra_emc_unreg_clk_notifier(void * data)1070 static void devm_tegra_emc_unreg_clk_notifier(void *data)
1071 {
1072 	struct tegra_emc *emc = data;
1073 
1074 	clk_notifier_unregister(emc->clk, &emc->clk_nb);
1075 }
1076 
tegra_emc_init_clk(struct tegra_emc * emc)1077 static int tegra_emc_init_clk(struct tegra_emc *emc)
1078 {
1079 	int err;
1080 
1081 	tegra20_clk_set_emc_round_callback(emc_round_rate, emc);
1082 
1083 	err = devm_add_action_or_reset(emc->dev, devm_tegra_emc_unset_callback,
1084 				       NULL);
1085 	if (err)
1086 		return err;
1087 
1088 	emc->clk = devm_clk_get(emc->dev, NULL);
1089 	if (IS_ERR(emc->clk)) {
1090 		dev_err(emc->dev, "failed to get EMC clock: %pe\n", emc->clk);
1091 		return PTR_ERR(emc->clk);
1092 	}
1093 
1094 	err = clk_notifier_register(emc->clk, &emc->clk_nb);
1095 	if (err) {
1096 		dev_err(emc->dev, "failed to register clk notifier: %d\n", err);
1097 		return err;
1098 	}
1099 
1100 	err = devm_add_action_or_reset(emc->dev,
1101 				       devm_tegra_emc_unreg_clk_notifier, emc);
1102 	if (err)
1103 		return err;
1104 
1105 	return 0;
1106 }
1107 
tegra_emc_devfreq_target(struct device * dev,unsigned long * freq,u32 flags)1108 static int tegra_emc_devfreq_target(struct device *dev, unsigned long *freq,
1109 				    u32 flags)
1110 {
1111 	struct tegra_emc *emc = dev_get_drvdata(dev);
1112 	struct dev_pm_opp *opp;
1113 	unsigned long rate;
1114 
1115 	opp = devfreq_recommended_opp(dev, freq, flags);
1116 	if (IS_ERR(opp)) {
1117 		dev_err(dev, "failed to find opp for %lu Hz\n", *freq);
1118 		return PTR_ERR(opp);
1119 	}
1120 
1121 	rate = dev_pm_opp_get_freq(opp);
1122 	dev_pm_opp_put(opp);
1123 
1124 	return emc_set_min_rate(emc, rate, EMC_RATE_DEVFREQ);
1125 }
1126 
tegra_emc_devfreq_get_dev_status(struct device * dev,struct devfreq_dev_status * stat)1127 static int tegra_emc_devfreq_get_dev_status(struct device *dev,
1128 					    struct devfreq_dev_status *stat)
1129 {
1130 	struct tegra_emc *emc = dev_get_drvdata(dev);
1131 
1132 	/* freeze counters */
1133 	writel_relaxed(EMC_PWR_GATHER_DISABLE, emc->regs + EMC_STAT_CONTROL);
1134 
1135 	/*
1136 	 *  busy_time: number of clocks EMC request was accepted
1137 	 * total_time: number of clocks PWR_GATHER control was set to ENABLE
1138 	 */
1139 	stat->busy_time = readl_relaxed(emc->regs + EMC_STAT_PWR_COUNT);
1140 	stat->total_time = readl_relaxed(emc->regs + EMC_STAT_PWR_CLOCKS);
1141 	stat->current_frequency = clk_get_rate(emc->clk);
1142 
1143 	/* clear counters and restart */
1144 	writel_relaxed(EMC_PWR_GATHER_CLEAR, emc->regs + EMC_STAT_CONTROL);
1145 	writel_relaxed(EMC_PWR_GATHER_ENABLE, emc->regs + EMC_STAT_CONTROL);
1146 
1147 	return 0;
1148 }
1149 
1150 static struct devfreq_dev_profile tegra_emc_devfreq_profile = {
1151 	.polling_ms = 30,
1152 	.target = tegra_emc_devfreq_target,
1153 	.get_dev_status = tegra_emc_devfreq_get_dev_status,
1154 };
1155 
tegra_emc_devfreq_init(struct tegra_emc * emc)1156 static int tegra_emc_devfreq_init(struct tegra_emc *emc)
1157 {
1158 	struct devfreq *devfreq;
1159 
1160 	/*
1161 	 * PWR_COUNT is 1/2 of PWR_CLOCKS at max, and thus, the up-threshold
1162 	 * should be less than 50.  Secondly, multiple active memory clients
1163 	 * may cause over 20% of lost clock cycles due to stalls caused by
1164 	 * competing memory accesses.  This means that threshold should be
1165 	 * set to a less than 30 in order to have a properly working governor.
1166 	 */
1167 	emc->ondemand_data.upthreshold = 20;
1168 
1169 	/*
1170 	 * Reset statistic gathers state, select global bandwidth for the
1171 	 * statistics collection mode and set clocks counter saturation
1172 	 * limit to maximum.
1173 	 */
1174 	writel_relaxed(0x00000000, emc->regs + EMC_STAT_CONTROL);
1175 	writel_relaxed(0x00000000, emc->regs + EMC_STAT_LLMC_CONTROL);
1176 	writel_relaxed(0xffffffff, emc->regs + EMC_STAT_PWR_CLOCK_LIMIT);
1177 
1178 	devfreq = devm_devfreq_add_device(emc->dev, &tegra_emc_devfreq_profile,
1179 					  DEVFREQ_GOV_SIMPLE_ONDEMAND,
1180 					  &emc->ondemand_data);
1181 	if (IS_ERR(devfreq)) {
1182 		dev_err(emc->dev, "failed to initialize devfreq: %pe", devfreq);
1183 		return PTR_ERR(devfreq);
1184 	}
1185 
1186 	return 0;
1187 }
1188 
tegra_emc_probe(struct platform_device * pdev)1189 static int tegra_emc_probe(struct platform_device *pdev)
1190 {
1191 	struct tegra_core_opp_params opp_params = {};
1192 	struct device_node *np;
1193 	struct tegra_emc *emc;
1194 	int irq, err;
1195 
1196 	irq = platform_get_irq(pdev, 0);
1197 	if (irq < 0) {
1198 		dev_err(&pdev->dev, "please update your device tree\n");
1199 		return irq;
1200 	}
1201 
1202 	emc = devm_kzalloc(&pdev->dev, sizeof(*emc), GFP_KERNEL);
1203 	if (!emc)
1204 		return -ENOMEM;
1205 
1206 	mutex_init(&emc->rate_lock);
1207 	emc->clk_nb.notifier_call = tegra_emc_clk_change_notify;
1208 	emc->dev = &pdev->dev;
1209 
1210 	emc->regs = devm_platform_ioremap_resource(pdev, 0);
1211 	if (IS_ERR(emc->regs))
1212 		return PTR_ERR(emc->regs);
1213 
1214 	err = emc_setup_hw(emc);
1215 	if (err)
1216 		return err;
1217 
1218 	np = tegra_emc_find_node_by_ram_code(emc);
1219 	if (np) {
1220 		err = tegra_emc_load_timings_from_dt(emc, np);
1221 		of_node_put(np);
1222 		if (err)
1223 			return err;
1224 	}
1225 
1226 	err = devm_request_irq(&pdev->dev, irq, tegra_emc_isr, 0,
1227 			       dev_name(&pdev->dev), emc);
1228 	if (err) {
1229 		dev_err(&pdev->dev, "failed to request IRQ: %d\n", err);
1230 		return err;
1231 	}
1232 
1233 	err = tegra_emc_init_clk(emc);
1234 	if (err)
1235 		return err;
1236 
1237 	opp_params.init_state = true;
1238 
1239 	err = devm_tegra_core_dev_init_opp_table(&pdev->dev, &opp_params);
1240 	if (err)
1241 		return err;
1242 
1243 	platform_set_drvdata(pdev, emc);
1244 	tegra_emc_rate_requests_init(emc);
1245 	tegra_emc_debugfs_init(emc);
1246 	tegra_emc_interconnect_init(emc);
1247 	tegra_emc_devfreq_init(emc);
1248 
1249 	/*
1250 	 * Don't allow the kernel module to be unloaded. Unloading adds some
1251 	 * extra complexity which doesn't really worth the effort in a case of
1252 	 * this driver.
1253 	 */
1254 	try_module_get(THIS_MODULE);
1255 
1256 	return 0;
1257 }
1258 
1259 static const struct of_device_id tegra_emc_of_match[] = {
1260 	{ .compatible = "nvidia,tegra20-emc", },
1261 	{},
1262 };
1263 MODULE_DEVICE_TABLE(of, tegra_emc_of_match);
1264 
1265 static struct platform_driver tegra_emc_driver = {
1266 	.probe = tegra_emc_probe,
1267 	.driver = {
1268 		.name = "tegra20-emc",
1269 		.of_match_table = tegra_emc_of_match,
1270 		.suppress_bind_attrs = true,
1271 		.sync_state = icc_sync_state,
1272 	},
1273 };
1274 module_platform_driver(tegra_emc_driver);
1275 
1276 MODULE_AUTHOR("Dmitry Osipenko <digetx@gmail.com>");
1277 MODULE_DESCRIPTION("NVIDIA Tegra20 EMC driver");
1278 MODULE_SOFTDEP("pre: governor_simpleondemand");
1279 MODULE_LICENSE("GPL v2");
1280