summaryrefslogtreecommitdiff
path: root/drivers/staging/greybus/arche-apb-ctrl.c
blob: bbf3ba744fc441b71e84cd38ec65bfadeb103b2c (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
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
// SPDX-License-Identifier: GPL-2.0
/*
 * Arche Platform driver to control APB.
 *
 * Copyright 2014-2015 Google Inc.
 * Copyright 2014-2015 Linaro Ltd.
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/interrupt.h>
#include <linux/of_irq.h>
#include <linux/module.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
#include <linux/regulator/consumer.h>
#include <linux/spinlock.h>
#include "arche_platform.h"

static void apb_bootret_deassert(struct device *dev);

struct arche_apb_ctrl_drvdata {
	/* Control GPIO signals to and from AP <=> AP Bridges */
	struct gpio_desc *resetn;
	struct gpio_desc *boot_ret;
	struct gpio_desc *pwroff;
	struct gpio_desc *wake_in;
	struct gpio_desc *wake_out;
	struct gpio_desc *pwrdn;

	enum arche_platform_state state;
	bool init_disabled;

	struct regulator *vcore;
	struct regulator *vio;

	struct gpio_desc *clk_en;
	struct clk *clk;

	struct pinctrl *pinctrl;
	struct pinctrl_state *pin_default;

	/* V2: SPI Bus control  */
	struct gpio_desc *spi_en;
	bool spi_en_polarity_high;
};

/*
 * Note that these low level api's are active high
 */
static inline void deassert_reset(struct gpio_desc *gpio)
{
	gpiod_set_raw_value(gpio, 1);
}

static inline void assert_reset(struct gpio_desc *gpio)
{
	gpiod_set_raw_value(gpio, 0);
}

/*
 * Note: Please do not modify the below sequence, as it is as per the spec
 */
static int coldboot_seq(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct arche_apb_ctrl_drvdata *apb = platform_get_drvdata(pdev);
	int ret;

	if (apb->init_disabled ||
	    apb->state == ARCHE_PLATFORM_STATE_ACTIVE)
		return 0;

	/* Hold APB in reset state */
	assert_reset(apb->resetn);

	if (apb->state == ARCHE_PLATFORM_STATE_FW_FLASHING && apb->spi_en)
		devm_gpiod_put(dev, apb->spi_en);

	/* Enable power to APB */
	if (!IS_ERR(apb->vcore)) {
		ret = regulator_enable(apb->vcore);
		if (ret) {
			dev_err(dev, "failed to enable core regulator\n");
			return ret;
		}
	}

	if (!IS_ERR(apb->vio)) {
		ret = regulator_enable(apb->vio);
		if (ret) {
			dev_err(dev, "failed to enable IO regulator\n");
			return ret;
		}
	}

	apb_bootret_deassert(dev);

	/* On DB3 clock was not mandatory */
	if (apb->clk_en)
		gpiod_set_value(apb->clk_en, 1);

	usleep_range(100, 200);

	/* deassert reset to APB : Active-low signal */
	deassert_reset(apb->resetn);

	apb->state = ARCHE_PLATFORM_STATE_ACTIVE;

	return 0;
}

static int fw_flashing_seq(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct arche_apb_ctrl_drvdata *apb = platform_get_drvdata(pdev);
	int ret;

	if (apb->init_disabled ||
	    apb->state == ARCHE_PLATFORM_STATE_FW_FLASHING)
		return 0;

	ret = regulator_enable(apb->vcore);
	if (ret) {
		dev_err(dev, "failed to enable core regulator\n");
		return ret;
	}

	ret = regulator_enable(apb->vio);
	if (ret) {
		dev_err(dev, "failed to enable IO regulator\n");
		return ret;
	}

	if (apb->spi_en) {
		unsigned long flags;

		if (apb->spi_en_polarity_high)
			flags = GPIOD_OUT_HIGH;
		else
			flags = GPIOD_OUT_LOW;

		apb->spi_en = devm_gpiod_get(dev, "spi-en", flags);
		if (IS_ERR(apb->spi_en)) {
			ret = PTR_ERR(apb->spi_en);
			dev_err(dev, "Failed requesting SPI bus en GPIO: %d\n",
				ret);
			return ret;
		}
	}

	/* for flashing device should be in reset state */
	assert_reset(apb->resetn);
	apb->state = ARCHE_PLATFORM_STATE_FW_FLASHING;

	return 0;
}

static int standby_boot_seq(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct arche_apb_ctrl_drvdata *apb = platform_get_drvdata(pdev);

	if (apb->init_disabled)
		return 0;

	/*
	 * Even if it is in OFF state,
	 * then we do not want to change the state
	 */
	if (apb->state == ARCHE_PLATFORM_STATE_STANDBY ||
	    apb->state == ARCHE_PLATFORM_STATE_OFF)
		return 0;

	if (apb->state == ARCHE_PLATFORM_STATE_FW_FLASHING && apb->spi_en)
		devm_gpiod_put(dev, apb->spi_en);

	/*
	 * As per WDM spec, do nothing
	 *
	 * Pasted from WDM spec,
	 *  - A falling edge on POWEROFF_L is detected (a)
	 *  - WDM enters standby mode, but no output signals are changed
	 */

	/* TODO: POWEROFF_L is input to WDM module  */
	apb->state = ARCHE_PLATFORM_STATE_STANDBY;
	return 0;
}

static void poweroff_seq(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct arche_apb_ctrl_drvdata *apb = platform_get_drvdata(pdev);

	if (apb->init_disabled || apb->state == ARCHE_PLATFORM_STATE_OFF)
		return;

	if (apb->state == ARCHE_PLATFORM_STATE_FW_FLASHING && apb->spi_en)
		devm_gpiod_put(dev, apb->spi_en);

	/* disable the clock */
	if (apb->clk_en)
		gpiod_set_value(apb->clk_en, 0);

	if (!IS_ERR(apb->vcore) && regulator_is_enabled(apb->vcore) > 0)
		regulator_disable(apb->vcore);

	if (!IS_ERR(apb->vio) && regulator_is_enabled(apb->vio) > 0)
		regulator_disable(apb->vio);

	/* As part of exit, put APB back in reset state */
	assert_reset(apb->resetn);
	apb->state = ARCHE_PLATFORM_STATE_OFF;

	/* TODO: May have to send an event to SVC about this exit */
}

static void apb_bootret_deassert(struct device *dev)
{
	struct arche_apb_ctrl_drvdata *apb = dev_get_drvdata(dev);

	gpiod_set_value(apb->boot_ret, 0);
}

int apb_ctrl_coldboot(struct device *dev)
{
	return coldboot_seq(to_platform_device(dev));
}

int apb_ctrl_fw_flashing(struct device *dev)
{
	return fw_flashing_seq(to_platform_device(dev));
}

int apb_ctrl_standby_boot(struct device *dev)
{
	return standby_boot_seq(to_platform_device(dev));
}

void apb_ctrl_poweroff(struct device *dev)
{
	poweroff_seq(to_platform_device(dev));
}

static ssize_t state_store(struct device *dev,
			   struct device_attribute *attr,
			   const char *buf, size_t count)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct arche_apb_ctrl_drvdata *apb = platform_get_drvdata(pdev);
	int ret = 0;
	bool is_disabled;

	if (sysfs_streq(buf, "off")) {
		if (apb->state == ARCHE_PLATFORM_STATE_OFF)
			return count;

		poweroff_seq(pdev);
	} else if (sysfs_streq(buf, "active")) {
		if (apb->state == ARCHE_PLATFORM_STATE_ACTIVE)
			return count;

		poweroff_seq(pdev);
		is_disabled = apb->init_disabled;
		apb->init_disabled = false;
		ret = coldboot_seq(pdev);
		if (ret)
			apb->init_disabled = is_disabled;
	} else if (sysfs_streq(buf, "standby")) {
		if (apb->state == ARCHE_PLATFORM_STATE_STANDBY)
			return count;

		ret = standby_boot_seq(pdev);
	} else if (sysfs_streq(buf, "fw_flashing")) {
		if (apb->state == ARCHE_PLATFORM_STATE_FW_FLASHING)
			return count;

		/*
		 * First we want to make sure we power off everything
		 * and then enter FW flashing state
		 */
		poweroff_seq(pdev);
		ret = fw_flashing_seq(pdev);
	} else {
		dev_err(dev, "unknown state\n");
		ret = -EINVAL;
	}

	return ret ? ret : count;
}

static ssize_t state_show(struct device *dev,
			  struct device_attribute *attr, char *buf)
{
	struct arche_apb_ctrl_drvdata *apb = dev_get_drvdata(dev);

	switch (apb->state) {
	case ARCHE_PLATFORM_STATE_OFF:
		return sprintf(buf, "off%s\n",
				apb->init_disabled ? ",disabled" : "");
	case ARCHE_PLATFORM_STATE_ACTIVE:
		return sprintf(buf, "active\n");
	case ARCHE_PLATFORM_STATE_STANDBY:
		return sprintf(buf, "standby\n");
	case ARCHE_PLATFORM_STATE_FW_FLASHING:
		return sprintf(buf, "fw_flashing\n");
	default:
		return sprintf(buf, "unknown state\n");
	}
}

static DEVICE_ATTR_RW(state);

static int apb_ctrl_get_devtree_data(struct platform_device *pdev,
				     struct arche_apb_ctrl_drvdata *apb)
{
	struct device *dev = &pdev->dev;
	int ret;

	apb->resetn = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
	if (IS_ERR(apb->resetn)) {
		ret = PTR_ERR(apb->resetn);
		dev_err(dev, "Failed requesting reset GPIO: %d\n", ret);
		return ret;
	}

	apb->boot_ret = devm_gpiod_get(dev, "boot-ret", GPIOD_OUT_LOW);
	if (IS_ERR(apb->boot_ret)) {
		ret = PTR_ERR(apb->boot_ret);
		dev_err(dev, "Failed requesting bootret GPIO: %d\n", ret);
		return ret;
	}

	/* It's not mandatory to support power management interface */
	apb->pwroff = devm_gpiod_get_optional(dev, "pwr-off", GPIOD_IN);
	if (IS_ERR(apb->pwroff)) {
		ret = PTR_ERR(apb->pwroff);
		dev_err(dev, "Failed requesting pwroff_n GPIO: %d\n", ret);
		return ret;
	}

	/* Do not make clock mandatory as of now (for DB3) */
	apb->clk_en = devm_gpiod_get_optional(dev, "clock-en", GPIOD_OUT_LOW);
	if (IS_ERR(apb->clk_en)) {
		ret = PTR_ERR(apb->clk_en);
		dev_err(dev, "Failed requesting APB clock en GPIO: %d\n", ret);
		return ret;
	}

	apb->pwrdn = devm_gpiod_get(dev, "pwr-down", GPIOD_OUT_LOW);
	if (IS_ERR(apb->pwrdn)) {
		ret = PTR_ERR(apb->pwrdn);
		dev_warn(dev, "Failed requesting power down GPIO: %d\n", ret);
		return ret;
	}

	/* Regulators are optional, as we may have fixed supply coming in */
	apb->vcore = devm_regulator_get(dev, "vcore");
	if (IS_ERR(apb->vcore))
		dev_warn(dev, "no core regulator found\n");

	apb->vio = devm_regulator_get(dev, "vio");
	if (IS_ERR(apb->vio))
		dev_warn(dev, "no IO regulator found\n");

	apb->pinctrl = devm_pinctrl_get(&pdev->dev);
	if (IS_ERR(apb->pinctrl)) {
		dev_err(&pdev->dev, "could not get pinctrl handle\n");
		return PTR_ERR(apb->pinctrl);
	}
	apb->pin_default = pinctrl_lookup_state(apb->pinctrl, "default");
	if (IS_ERR(apb->pin_default)) {
		dev_err(&pdev->dev, "could not get default pin state\n");
		return PTR_ERR(apb->pin_default);
	}

	/* Only applicable for platform >= V2 */
	if (of_property_read_bool(pdev->dev.of_node, "gb,spi-en-active-high"))
		apb->spi_en_polarity_high = true;

	return 0;
}

static int arche_apb_ctrl_probe(struct platform_device *pdev)
{
	int ret;
	struct arche_apb_ctrl_drvdata *apb;
	struct device *dev = &pdev->dev;

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

	ret = apb_ctrl_get_devtree_data(pdev, apb);
	if (ret) {
		dev_err(dev, "failed to get apb devicetree data %d\n", ret);
		return ret;
	}

	/* Initially set APB to OFF state */
	apb->state = ARCHE_PLATFORM_STATE_OFF;
	/* Check whether device needs to be enabled on boot */
	if (of_property_read_bool(pdev->dev.of_node, "arche,init-disable"))
		apb->init_disabled = true;

	platform_set_drvdata(pdev, apb);

	/* Create sysfs interface to allow user to change state dynamically */
	ret = device_create_file(dev, &dev_attr_state);
	if (ret) {
		dev_err(dev, "failed to create state file in sysfs\n");
		return ret;
	}

	dev_info(&pdev->dev, "Device registered successfully\n");
	return 0;
}

static int arche_apb_ctrl_remove(struct platform_device *pdev)
{
	device_remove_file(&pdev->dev, &dev_attr_state);
	poweroff_seq(pdev);
	platform_set_drvdata(pdev, NULL);

	return 0;
}

static int __maybe_unused arche_apb_ctrl_suspend(struct device *dev)
{
	/*
	 * If timing profile permits, we may shutdown bridge
	 * completely
	 *
	 * TODO: sequence ??
	 *
	 * Also, need to make sure we meet precondition for unipro suspend
	 * Precondition: Definition ???
	 */
	return 0;
}

static int __maybe_unused arche_apb_ctrl_resume(struct device *dev)
{
	/*
	 * Atleast for ES2 we have to meet the delay requirement between
	 * unipro switch and AP bridge init, depending on whether bridge is in
	 * OFF state or standby state.
	 *
	 * Based on whether bridge is in standby or OFF state we may have to
	 * assert multiple signals. Please refer to WDM spec, for more info.
	 *
	 */
	return 0;
}

static void arche_apb_ctrl_shutdown(struct platform_device *pdev)
{
	apb_ctrl_poweroff(&pdev->dev);
}

static SIMPLE_DEV_PM_OPS(arche_apb_ctrl_pm_ops, arche_apb_ctrl_suspend,
			 arche_apb_ctrl_resume);

static const struct of_device_id arche_apb_ctrl_of_match[] = {
	{ .compatible = "usbffff,2", },
	{ },
};

static struct platform_driver arche_apb_ctrl_device_driver = {
	.probe		= arche_apb_ctrl_probe,
	.remove		= arche_apb_ctrl_remove,
	.shutdown	= arche_apb_ctrl_shutdown,
	.driver		= {
		.name	= "arche-apb-ctrl",
		.pm	= &arche_apb_ctrl_pm_ops,
		.of_match_table = arche_apb_ctrl_of_match,
	}
};

int __init arche_apb_init(void)
{
	return platform_driver_register(&arche_apb_ctrl_device_driver);
}

void __exit arche_apb_exit(void)
{
	platform_driver_unregister(&arche_apb_ctrl_device_driver);
}