summaryrefslogtreecommitdiff
path: root/drivers/i2c/busses/i2c-efm32.c
blob: f7eccd682de961aa2252b1a780f37cc15f293941 (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
/*
 * Copyright (C) 2014 Uwe Kleine-Koenig for Pengutronix
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License version 2 as published by the
 * Free Software Foundation.
 */
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/i2c.h>
#include <linux/io.h>
#include <linux/interrupt.h>
#include <linux/err.h>
#include <linux/clk.h>

#define DRIVER_NAME "efm32-i2c"

#define MASK_VAL(mask, val)		((val << __ffs(mask)) & mask)

#define REG_CTRL		0x00
#define REG_CTRL_EN			0x00001
#define REG_CTRL_SLAVE			0x00002
#define REG_CTRL_AUTOACK		0x00004
#define REG_CTRL_AUTOSE			0x00008
#define REG_CTRL_AUTOSN			0x00010
#define REG_CTRL_ARBDIS			0x00020
#define REG_CTRL_GCAMEN			0x00040
#define REG_CTRL_CLHR__MASK		0x00300
#define REG_CTRL_BITO__MASK		0x03000
#define REG_CTRL_BITO_OFF		0x00000
#define REG_CTRL_BITO_40PCC		0x01000
#define REG_CTRL_BITO_80PCC		0x02000
#define REG_CTRL_BITO_160PCC		0x03000
#define REG_CTRL_GIBITO			0x08000
#define REG_CTRL_CLTO__MASK		0x70000
#define REG_CTRL_CLTO_OFF		0x00000

#define REG_CMD			0x04
#define REG_CMD_START			0x00001
#define REG_CMD_STOP			0x00002
#define REG_CMD_ACK			0x00004
#define REG_CMD_NACK			0x00008
#define REG_CMD_CONT			0x00010
#define REG_CMD_ABORT			0x00020
#define REG_CMD_CLEARTX			0x00040
#define REG_CMD_CLEARPC			0x00080

#define REG_STATE		0x08
#define REG_STATE_BUSY			0x00001
#define REG_STATE_MASTER		0x00002
#define REG_STATE_TRANSMITTER		0x00004
#define REG_STATE_NACKED		0x00008
#define REG_STATE_BUSHOLD		0x00010
#define REG_STATE_STATE__MASK		0x000e0
#define REG_STATE_STATE_IDLE		0x00000
#define REG_STATE_STATE_WAIT		0x00020
#define REG_STATE_STATE_START		0x00040
#define REG_STATE_STATE_ADDR		0x00060
#define REG_STATE_STATE_ADDRACK		0x00080
#define REG_STATE_STATE_DATA		0x000a0
#define REG_STATE_STATE_DATAACK		0x000c0

#define REG_STATUS		0x0c
#define REG_STATUS_PSTART		0x00001
#define REG_STATUS_PSTOP		0x00002
#define REG_STATUS_PACK			0x00004
#define REG_STATUS_PNACK		0x00008
#define REG_STATUS_PCONT		0x00010
#define REG_STATUS_PABORT		0x00020
#define REG_STATUS_TXC			0x00040
#define REG_STATUS_TXBL			0x00080
#define REG_STATUS_RXDATAV		0x00100

#define REG_CLKDIV		0x10
#define REG_CLKDIV_DIV__MASK		0x001ff
#define REG_CLKDIV_DIV(div)		MASK_VAL(REG_CLKDIV_DIV__MASK, (div))

#define REG_SADDR		0x14
#define REG_SADDRMASK		0x18
#define REG_RXDATA		0x1c
#define REG_RXDATAP		0x20
#define REG_TXDATA		0x24
#define REG_IF			0x28
#define REG_IF_START			0x00001
#define REG_IF_RSTART			0x00002
#define REG_IF_ADDR			0x00004
#define REG_IF_TXC			0x00008
#define REG_IF_TXBL			0x00010
#define REG_IF_RXDATAV			0x00020
#define REG_IF_ACK			0x00040
#define REG_IF_NACK			0x00080
#define REG_IF_MSTOP			0x00100
#define REG_IF_ARBLOST			0x00200
#define REG_IF_BUSERR			0x00400
#define REG_IF_BUSHOLD			0x00800
#define REG_IF_TXOF			0x01000
#define REG_IF_RXUF			0x02000
#define REG_IF_BITO			0x04000
#define REG_IF_CLTO			0x08000
#define REG_IF_SSTOP			0x10000

#define REG_IFS			0x2c
#define REG_IFC			0x30
#define REG_IFC__MASK			0x1ffcf

#define REG_IEN			0x34

#define REG_ROUTE		0x38
#define REG_ROUTE_SDAPEN		0x00001
#define REG_ROUTE_SCLPEN		0x00002
#define REG_ROUTE_LOCATION__MASK	0x00700
#define REG_ROUTE_LOCATION(n)		MASK_VAL(REG_ROUTE_LOCATION__MASK, (n))

struct efm32_i2c_ddata {
	struct i2c_adapter adapter;

	struct clk *clk;
	void __iomem *base;
	unsigned int irq;
	u8 location;
	unsigned long frequency;

	/* transfer data */
	struct completion done;
	struct i2c_msg *msgs;
	size_t num_msgs;
	size_t current_word, current_msg;
	int retval;
};

static u32 efm32_i2c_read32(struct efm32_i2c_ddata *ddata, unsigned offset)
{
	return readl(ddata->base + offset);
}

static void efm32_i2c_write32(struct efm32_i2c_ddata *ddata,
		unsigned offset, u32 value)
{
	writel(value, ddata->base + offset);
}

static void efm32_i2c_send_next_msg(struct efm32_i2c_ddata *ddata)
{
	struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];

	efm32_i2c_write32(ddata, REG_CMD, REG_CMD_START);
	efm32_i2c_write32(ddata, REG_TXDATA, cur_msg->addr << 1 |
			(cur_msg->flags & I2C_M_RD ? 1 : 0));
}

static void efm32_i2c_send_next_byte(struct efm32_i2c_ddata *ddata)
{
	struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];

	if (ddata->current_word >= cur_msg->len) {
		/* cur_msg completely transferred */
		ddata->current_word = 0;
		ddata->current_msg += 1;

		if (ddata->current_msg >= ddata->num_msgs) {
			efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
			complete(&ddata->done);
		} else {
			efm32_i2c_send_next_msg(ddata);
		}
	} else {
		efm32_i2c_write32(ddata, REG_TXDATA,
				cur_msg->buf[ddata->current_word++]);
	}
}

static void efm32_i2c_recv_next_byte(struct efm32_i2c_ddata *ddata)
{
	struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];

	cur_msg->buf[ddata->current_word] = efm32_i2c_read32(ddata, REG_RXDATA);
	ddata->current_word += 1;
	if (ddata->current_word >= cur_msg->len) {
		/* cur_msg completely transferred */
		ddata->current_word = 0;
		ddata->current_msg += 1;

		efm32_i2c_write32(ddata, REG_CMD, REG_CMD_NACK);

		if (ddata->current_msg >= ddata->num_msgs) {
			efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
			complete(&ddata->done);
		} else {
			efm32_i2c_send_next_msg(ddata);
		}
	} else {
		efm32_i2c_write32(ddata, REG_CMD, REG_CMD_ACK);
	}
}

static irqreturn_t efm32_i2c_irq(int irq, void *dev_id)
{
	struct efm32_i2c_ddata *ddata = dev_id;
	struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];
	u32 irqflag = efm32_i2c_read32(ddata, REG_IF);
	u32 state = efm32_i2c_read32(ddata, REG_STATE);

	efm32_i2c_write32(ddata, REG_IFC, irqflag & REG_IFC__MASK);

	switch (state & REG_STATE_STATE__MASK) {
	case REG_STATE_STATE_IDLE:
		/* arbitration lost? */
		ddata->retval = -EAGAIN;
		complete(&ddata->done);
		break;
	case REG_STATE_STATE_WAIT:
		/*
		 * huh, this shouldn't happen.
		 * Reset hardware state and get out
		 */
		ddata->retval = -EIO;
		efm32_i2c_write32(ddata, REG_CMD,
				REG_CMD_STOP | REG_CMD_ABORT |
				REG_CMD_CLEARTX | REG_CMD_CLEARPC);
		complete(&ddata->done);
		break;
	case REG_STATE_STATE_START:
		/* "caller" is expected to send an address */
		break;
	case REG_STATE_STATE_ADDR:
		/* wait for Ack or NAck of slave */
		break;
	case REG_STATE_STATE_ADDRACK:
		if (state & REG_STATE_NACKED) {
			efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
			ddata->retval = -ENXIO;
			complete(&ddata->done);
		} else if (cur_msg->flags & I2C_M_RD) {
			/* wait for slave to send first data byte */
		} else {
			efm32_i2c_send_next_byte(ddata);
		}
		break;
	case REG_STATE_STATE_DATA:
		if (cur_msg->flags & I2C_M_RD) {
			efm32_i2c_recv_next_byte(ddata);
		} else {
			/* wait for Ack or Nack of slave */
		}
		break;
	case REG_STATE_STATE_DATAACK:
		if (state & REG_STATE_NACKED) {
			efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
			complete(&ddata->done);
		} else {
			efm32_i2c_send_next_byte(ddata);
		}
	}

	return IRQ_HANDLED;
}

static int efm32_i2c_master_xfer(struct i2c_adapter *adap,
		struct i2c_msg *msgs, int num)
{
	struct efm32_i2c_ddata *ddata = i2c_get_adapdata(adap);
	int ret;

	if (ddata->msgs)
		return -EBUSY;

	ddata->msgs = msgs;
	ddata->num_msgs = num;
	ddata->current_word = 0;
	ddata->current_msg = 0;
	ddata->retval = -EIO;

	reinit_completion(&ddata->done);

	dev_dbg(&ddata->adapter.dev, "state: %08x, status: %08x\n",
			efm32_i2c_read32(ddata, REG_STATE),
			efm32_i2c_read32(ddata, REG_STATUS));

	efm32_i2c_send_next_msg(ddata);

	wait_for_completion(&ddata->done);

	if (ddata->current_msg >= ddata->num_msgs)
		ret = ddata->num_msgs;
	else
		ret = ddata->retval;

	return ret;
}

static u32 efm32_i2c_functionality(struct i2c_adapter *adap)
{
	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}

static const struct i2c_algorithm efm32_i2c_algo = {
	.master_xfer = efm32_i2c_master_xfer,
	.functionality = efm32_i2c_functionality,
};

static u32 efm32_i2c_get_configured_location(struct efm32_i2c_ddata *ddata)
{
	u32 reg = efm32_i2c_read32(ddata, REG_ROUTE);

	return (reg & REG_ROUTE_LOCATION__MASK) >>
		__ffs(REG_ROUTE_LOCATION__MASK);
}

static int efm32_i2c_probe(struct platform_device *pdev)
{
	struct efm32_i2c_ddata *ddata;
	struct resource *res;
	unsigned long rate;
	struct device_node *np = pdev->dev.of_node;
	u32 location, frequency;
	int ret;
	u32 clkdiv;

	if (!np)
		return -EINVAL;

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

	init_completion(&ddata->done);
	strlcpy(ddata->adapter.name, pdev->name, sizeof(ddata->adapter.name));
	ddata->adapter.owner = THIS_MODULE;
	ddata->adapter.algo = &efm32_i2c_algo;
	ddata->adapter.dev.parent = &pdev->dev;
	ddata->adapter.dev.of_node = pdev->dev.of_node;
	i2c_set_adapdata(&ddata->adapter, ddata);

	ddata->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(ddata->clk)) {
		ret = PTR_ERR(ddata->clk);
		dev_err(&pdev->dev, "failed to get clock: %d\n", ret);
		return ret;
	}

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res) {
		dev_err(&pdev->dev, "failed to determine base address\n");
		return -ENODEV;
	}

	if (resource_size(res) < 0x42) {
		dev_err(&pdev->dev, "memory resource too small\n");
		return -EINVAL;
	}

	ddata->base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(ddata->base))
		return PTR_ERR(ddata->base);

	ret = platform_get_irq(pdev, 0);
	if (ret <= 0) {
		dev_err(&pdev->dev, "failed to get irq (%d)\n", ret);
		if (!ret)
			ret = -EINVAL;
		return ret;
	}

	ddata->irq = ret;

	ret = clk_prepare_enable(ddata->clk);
	if (ret < 0) {
		dev_err(&pdev->dev, "failed to enable clock (%d)\n", ret);
		return ret;
	}

	ret = of_property_read_u32(np, "efm32,location", &location);
	if (!ret) {
		dev_dbg(&pdev->dev, "using location %u\n", location);
	} else {
		/* default to location configured in hardware */
		location = efm32_i2c_get_configured_location(ddata);

		dev_info(&pdev->dev, "fall back to location %u\n", location);
	}

	ddata->location = location;

	ret = of_property_read_u32(np, "clock-frequency", &frequency);
	if (!ret) {
		dev_dbg(&pdev->dev, "using frequency %u\n", frequency);
	} else {
		frequency = 100000;
		dev_info(&pdev->dev, "defaulting to 100 kHz\n");
	}
	ddata->frequency = frequency;

	rate = clk_get_rate(ddata->clk);
	if (!rate) {
		dev_err(&pdev->dev, "there is no input clock available\n");
		ret = -EINVAL;
		goto err_disable_clk;
	}
	clkdiv = DIV_ROUND_UP(rate, 8 * ddata->frequency) - 1;
	if (clkdiv >= 0x200) {
		dev_err(&pdev->dev,
				"input clock too fast (%lu) to divide down to bus freq (%lu)",
				rate, ddata->frequency);
		ret = -EINVAL;
		goto err_disable_clk;
	}

	dev_dbg(&pdev->dev, "input clock = %lu, bus freq = %lu, clkdiv = %lu\n",
			rate, ddata->frequency, (unsigned long)clkdiv);
	efm32_i2c_write32(ddata, REG_CLKDIV, REG_CLKDIV_DIV(clkdiv));

	efm32_i2c_write32(ddata, REG_ROUTE, REG_ROUTE_SDAPEN |
			REG_ROUTE_SCLPEN |
			REG_ROUTE_LOCATION(ddata->location));

	efm32_i2c_write32(ddata, REG_CTRL, REG_CTRL_EN |
			REG_CTRL_BITO_160PCC | 0 * REG_CTRL_GIBITO);

	efm32_i2c_write32(ddata, REG_IFC, REG_IFC__MASK);
	efm32_i2c_write32(ddata, REG_IEN, REG_IF_TXC | REG_IF_ACK | REG_IF_NACK
			| REG_IF_ARBLOST | REG_IF_BUSERR | REG_IF_RXDATAV);

	/* to make bus idle */
	efm32_i2c_write32(ddata, REG_CMD, REG_CMD_ABORT);

	ret = request_irq(ddata->irq, efm32_i2c_irq, 0, DRIVER_NAME, ddata);
	if (ret < 0) {
		dev_err(&pdev->dev, "failed to request irq (%d)\n", ret);
		return ret;
	}

	ret = i2c_add_adapter(&ddata->adapter);
	if (ret) {
		dev_err(&pdev->dev, "failed to add i2c adapter (%d)\n", ret);
		free_irq(ddata->irq, ddata);

err_disable_clk:
		clk_disable_unprepare(ddata->clk);
	}
	return ret;
}

static int efm32_i2c_remove(struct platform_device *pdev)
{
	struct efm32_i2c_ddata *ddata = platform_get_drvdata(pdev);

	i2c_del_adapter(&ddata->adapter);
	free_irq(ddata->irq, ddata);
	clk_disable_unprepare(ddata->clk);

	return 0;
}

static const struct of_device_id efm32_i2c_dt_ids[] = {
	{
		.compatible = "energymicro,efm32-i2c",
	}, {
		/* sentinel */
	}
};
MODULE_DEVICE_TABLE(of, efm32_i2c_dt_ids);

static struct platform_driver efm32_i2c_driver = {
	.probe = efm32_i2c_probe,
	.remove = efm32_i2c_remove,

	.driver = {
		.name = DRIVER_NAME,
		.owner = THIS_MODULE,
		.of_match_table = efm32_i2c_dt_ids,
	},
};
module_platform_driver(efm32_i2c_driver);

MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>");
MODULE_DESCRIPTION("EFM32 i2c driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" DRIVER_NAME);