summaryrefslogtreecommitdiff
path: root/drivers/soc/aspeed/aspeed-lpc-snoop.c
blob: f3d8d53ab84de0434e2a0ce0295b249a3ec9bdce (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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright 2017 Google Inc
 *
 * Provides a simple driver to control the ASPEED LPC snoop interface which
 * allows the BMC to listen on and save the data written by
 * the host to an arbitrary LPC I/O port.
 *
 * Typically used by the BMC to "watch" host boot progress via port
 * 0x80 writes made by the BIOS during the boot process.
 */

#include <linux/bitops.h>
#include <linux/interrupt.h>
#include <linux/fs.h>
#include <linux/kfifo.h>
#include <linux/mfd/syscon.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/poll.h>
#include <linux/regmap.h>

#define DEVICE_NAME	"aspeed-lpc-snoop"

#define NUM_SNOOP_CHANNELS 2
#define SNOOP_FIFO_SIZE 2048

#define HICR5	0x0
#define HICR5_EN_SNP0W		BIT(0)
#define HICR5_ENINT_SNP0W	BIT(1)
#define HICR5_EN_SNP1W		BIT(2)
#define HICR5_ENINT_SNP1W	BIT(3)

#define HICR6	0x4
#define HICR6_STR_SNP0W		BIT(0)
#define HICR6_STR_SNP1W		BIT(1)
#define SNPWADR	0x10
#define SNPWADR_CH0_MASK	GENMASK(15, 0)
#define SNPWADR_CH0_SHIFT	0
#define SNPWADR_CH1_MASK	GENMASK(31, 16)
#define SNPWADR_CH1_SHIFT	16
#define SNPWDR	0x14
#define SNPWDR_CH0_MASK		GENMASK(7, 0)
#define SNPWDR_CH0_SHIFT	0
#define SNPWDR_CH1_MASK		GENMASK(15, 8)
#define SNPWDR_CH1_SHIFT	8
#define HICRB	0x80
#define HICRB_ENSNP0D		BIT(14)
#define HICRB_ENSNP1D		BIT(15)

struct aspeed_lpc_snoop_model_data {
	/* The ast2400 has bits 14 and 15 as reserved, whereas the ast2500
	 * can use them.
	 */
	unsigned int has_hicrb_ensnp;
};

struct aspeed_lpc_snoop_channel {
	struct kfifo		fifo;
	wait_queue_head_t	wq;
	struct miscdevice	miscdev;
};

struct aspeed_lpc_snoop {
	struct regmap		*regmap;
	int			irq;
	struct aspeed_lpc_snoop_channel chan[NUM_SNOOP_CHANNELS];
};

static struct aspeed_lpc_snoop_channel *snoop_file_to_chan(struct file *file)
{
	return container_of(file->private_data,
			    struct aspeed_lpc_snoop_channel,
			    miscdev);
}

static ssize_t snoop_file_read(struct file *file, char __user *buffer,
				size_t count, loff_t *ppos)
{
	struct aspeed_lpc_snoop_channel *chan = snoop_file_to_chan(file);
	unsigned int copied;
	int ret = 0;

	if (kfifo_is_empty(&chan->fifo)) {
		if (file->f_flags & O_NONBLOCK)
			return -EAGAIN;
		ret = wait_event_interruptible(chan->wq,
				!kfifo_is_empty(&chan->fifo));
		if (ret == -ERESTARTSYS)
			return -EINTR;
	}
	ret = kfifo_to_user(&chan->fifo, buffer, count, &copied);

	return ret ? ret : copied;
}

static __poll_t snoop_file_poll(struct file *file,
				    struct poll_table_struct *pt)
{
	struct aspeed_lpc_snoop_channel *chan = snoop_file_to_chan(file);

	poll_wait(file, &chan->wq, pt);
	return !kfifo_is_empty(&chan->fifo) ? EPOLLIN : 0;
}

static const struct file_operations snoop_fops = {
	.owner  = THIS_MODULE,
	.read   = snoop_file_read,
	.poll   = snoop_file_poll,
	.llseek = noop_llseek,
};

/* Save a byte to a FIFO and discard the oldest byte if FIFO is full */
static void put_fifo_with_discard(struct aspeed_lpc_snoop_channel *chan, u8 val)
{
	if (!kfifo_initialized(&chan->fifo))
		return;
	if (kfifo_is_full(&chan->fifo))
		kfifo_skip(&chan->fifo);
	kfifo_put(&chan->fifo, val);
	wake_up_interruptible(&chan->wq);
}

static irqreturn_t aspeed_lpc_snoop_irq(int irq, void *arg)
{
	struct aspeed_lpc_snoop *lpc_snoop = arg;
	u32 reg, data;

	if (regmap_read(lpc_snoop->regmap, HICR6, &reg))
		return IRQ_NONE;

	/* Check if one of the snoop channels is interrupting */
	reg &= (HICR6_STR_SNP0W | HICR6_STR_SNP1W);
	if (!reg)
		return IRQ_NONE;

	/* Ack pending IRQs */
	regmap_write(lpc_snoop->regmap, HICR6, reg);

	/* Read and save most recent snoop'ed data byte to FIFO */
	regmap_read(lpc_snoop->regmap, SNPWDR, &data);

	if (reg & HICR6_STR_SNP0W) {
		u8 val = (data & SNPWDR_CH0_MASK) >> SNPWDR_CH0_SHIFT;

		put_fifo_with_discard(&lpc_snoop->chan[0], val);
	}
	if (reg & HICR6_STR_SNP1W) {
		u8 val = (data & SNPWDR_CH1_MASK) >> SNPWDR_CH1_SHIFT;

		put_fifo_with_discard(&lpc_snoop->chan[1], val);
	}

	return IRQ_HANDLED;
}

static int aspeed_lpc_snoop_config_irq(struct aspeed_lpc_snoop *lpc_snoop,
				       struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	int rc;

	lpc_snoop->irq = platform_get_irq(pdev, 0);
	if (!lpc_snoop->irq)
		return -ENODEV;

	rc = devm_request_irq(dev, lpc_snoop->irq,
			      aspeed_lpc_snoop_irq, IRQF_SHARED,
			      DEVICE_NAME, lpc_snoop);
	if (rc < 0) {
		dev_warn(dev, "Unable to request IRQ %d\n", lpc_snoop->irq);
		lpc_snoop->irq = 0;
		return rc;
	}

	return 0;
}

static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
				   struct device *dev,
				   int channel, u16 lpc_port)
{
	int rc = 0;
	u32 hicr5_en, snpwadr_mask, snpwadr_shift, hicrb_en;
	const struct aspeed_lpc_snoop_model_data *model_data =
		of_device_get_match_data(dev);

	init_waitqueue_head(&lpc_snoop->chan[channel].wq);
	/* Create FIFO datastructure */
	rc = kfifo_alloc(&lpc_snoop->chan[channel].fifo,
			 SNOOP_FIFO_SIZE, GFP_KERNEL);
	if (rc)
		return rc;

	lpc_snoop->chan[channel].miscdev.minor = MISC_DYNAMIC_MINOR;
	lpc_snoop->chan[channel].miscdev.name =
		devm_kasprintf(dev, GFP_KERNEL, "%s%d", DEVICE_NAME, channel);
	lpc_snoop->chan[channel].miscdev.fops = &snoop_fops;
	lpc_snoop->chan[channel].miscdev.parent = dev;
	rc = misc_register(&lpc_snoop->chan[channel].miscdev);
	if (rc)
		return rc;

	/* Enable LPC snoop channel at requested port */
	switch (channel) {
	case 0:
		hicr5_en = HICR5_EN_SNP0W | HICR5_ENINT_SNP0W;
		snpwadr_mask = SNPWADR_CH0_MASK;
		snpwadr_shift = SNPWADR_CH0_SHIFT;
		hicrb_en = HICRB_ENSNP0D;
		break;
	case 1:
		hicr5_en = HICR5_EN_SNP1W | HICR5_ENINT_SNP1W;
		snpwadr_mask = SNPWADR_CH1_MASK;
		snpwadr_shift = SNPWADR_CH1_SHIFT;
		hicrb_en = HICRB_ENSNP1D;
		break;
	default:
		return -EINVAL;
	}

	regmap_update_bits(lpc_snoop->regmap, HICR5, hicr5_en, hicr5_en);
	regmap_update_bits(lpc_snoop->regmap, SNPWADR, snpwadr_mask,
			   lpc_port << snpwadr_shift);
	if (model_data->has_hicrb_ensnp)
		regmap_update_bits(lpc_snoop->regmap, HICRB,
				hicrb_en, hicrb_en);

	return rc;
}

static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
				     int channel)
{
	switch (channel) {
	case 0:
		regmap_update_bits(lpc_snoop->regmap, HICR5,
				   HICR5_EN_SNP0W | HICR5_ENINT_SNP0W,
				   0);
		break;
	case 1:
		regmap_update_bits(lpc_snoop->regmap, HICR5,
				   HICR5_EN_SNP1W | HICR5_ENINT_SNP1W,
				   0);
		break;
	default:
		return;
	}

	kfifo_free(&lpc_snoop->chan[channel].fifo);
	misc_deregister(&lpc_snoop->chan[channel].miscdev);
}

static int aspeed_lpc_snoop_probe(struct platform_device *pdev)
{
	struct aspeed_lpc_snoop *lpc_snoop;
	struct device *dev;
	u32 port;
	int rc;

	dev = &pdev->dev;

	lpc_snoop = devm_kzalloc(dev, sizeof(*lpc_snoop), GFP_KERNEL);
	if (!lpc_snoop)
		return -ENOMEM;

	lpc_snoop->regmap = syscon_node_to_regmap(
			pdev->dev.parent->of_node);
	if (IS_ERR(lpc_snoop->regmap)) {
		dev_err(dev, "Couldn't get regmap\n");
		return -ENODEV;
	}

	dev_set_drvdata(&pdev->dev, lpc_snoop);

	rc = of_property_read_u32_index(dev->of_node, "snoop-ports", 0, &port);
	if (rc) {
		dev_err(dev, "no snoop ports configured\n");
		return -ENODEV;
	}

	rc = aspeed_lpc_snoop_config_irq(lpc_snoop, pdev);
	if (rc)
		return rc;

	rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, 0, port);
	if (rc)
		return rc;

	/* Configuration of 2nd snoop channel port is optional */
	if (of_property_read_u32_index(dev->of_node, "snoop-ports",
				       1, &port) == 0) {
		rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, 1, port);
		if (rc)
			aspeed_lpc_disable_snoop(lpc_snoop, 0);
	}

	return rc;
}

static int aspeed_lpc_snoop_remove(struct platform_device *pdev)
{
	struct aspeed_lpc_snoop *lpc_snoop = dev_get_drvdata(&pdev->dev);

	/* Disable both snoop channels */
	aspeed_lpc_disable_snoop(lpc_snoop, 0);
	aspeed_lpc_disable_snoop(lpc_snoop, 1);

	return 0;
}

static const struct aspeed_lpc_snoop_model_data ast2400_model_data = {
	.has_hicrb_ensnp = 0,
};

static const struct aspeed_lpc_snoop_model_data ast2500_model_data = {
	.has_hicrb_ensnp = 1,
};

static const struct of_device_id aspeed_lpc_snoop_match[] = {
	{ .compatible = "aspeed,ast2400-lpc-snoop",
	  .data = &ast2400_model_data },
	{ .compatible = "aspeed,ast2500-lpc-snoop",
	  .data = &ast2500_model_data },
	{ },
};

static struct platform_driver aspeed_lpc_snoop_driver = {
	.driver = {
		.name		= DEVICE_NAME,
		.of_match_table = aspeed_lpc_snoop_match,
	},
	.probe = aspeed_lpc_snoop_probe,
	.remove = aspeed_lpc_snoop_remove,
};

module_platform_driver(aspeed_lpc_snoop_driver);

MODULE_DEVICE_TABLE(of, aspeed_lpc_snoop_match);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Robert Lippert <rlippert@google.com>");
MODULE_DESCRIPTION("Linux driver to control Aspeed LPC snoop functionality");