xref: /openbmc/linux/drivers/net/ieee802154/cc2520.c (revision 35267cea)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Driver for TI CC2520 802.15.4 Wireless-PAN Networking controller
3  *
4  * Copyright (C) 2014 Varka Bhadram <varkab@cdac.in>
5  *		      Md.Jamal Mohiuddin <mjmohiuddin@cdac.in>
6  *		      P Sowjanya <sowjanyap@cdac.in>
7  */
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/gpio.h>
11 #include <linux/delay.h>
12 #include <linux/spi/spi.h>
13 #include <linux/spi/cc2520.h>
14 #include <linux/workqueue.h>
15 #include <linux/interrupt.h>
16 #include <linux/skbuff.h>
17 #include <linux/of_gpio.h>
18 #include <linux/ieee802154.h>
19 #include <linux/crc-ccitt.h>
20 #include <asm/unaligned.h>
21 
22 #include <net/mac802154.h>
23 #include <net/cfg802154.h>
24 
25 #define	SPI_COMMAND_BUFFER	3
26 #define	HIGH			1
27 #define	LOW			0
28 #define	STATE_IDLE		0
29 #define	RSSI_VALID		0
30 #define	RSSI_OFFSET		78
31 
32 #define	CC2520_RAM_SIZE		640
33 #define	CC2520_FIFO_SIZE	128
34 
35 #define	CC2520RAM_TXFIFO	0x100
36 #define	CC2520RAM_RXFIFO	0x180
37 #define	CC2520RAM_IEEEADDR	0x3EA
38 #define	CC2520RAM_PANID		0x3F2
39 #define	CC2520RAM_SHORTADDR	0x3F4
40 
41 #define	CC2520_FREG_MASK	0x3F
42 
43 /* status byte values */
44 #define	CC2520_STATUS_XOSC32M_STABLE	BIT(7)
45 #define	CC2520_STATUS_RSSI_VALID	BIT(6)
46 #define	CC2520_STATUS_TX_UNDERFLOW	BIT(3)
47 
48 /* IEEE-802.15.4 defined constants (2.4 GHz logical channels) */
49 #define	CC2520_MINCHANNEL		11
50 #define	CC2520_MAXCHANNEL		26
51 #define	CC2520_CHANNEL_SPACING		5
52 
53 /* command strobes */
54 #define	CC2520_CMD_SNOP			0x00
55 #define	CC2520_CMD_IBUFLD		0x02
56 #define	CC2520_CMD_SIBUFEX		0x03
57 #define	CC2520_CMD_SSAMPLECCA		0x04
58 #define	CC2520_CMD_SRES			0x0f
59 #define	CC2520_CMD_MEMORY_MASK		0x0f
60 #define	CC2520_CMD_MEMORY_READ		0x10
61 #define	CC2520_CMD_MEMORY_WRITE		0x20
62 #define	CC2520_CMD_RXBUF		0x30
63 #define	CC2520_CMD_RXBUFCP		0x38
64 #define	CC2520_CMD_RXBUFMOV		0x32
65 #define	CC2520_CMD_TXBUF		0x3A
66 #define	CC2520_CMD_TXBUFCP		0x3E
67 #define	CC2520_CMD_RANDOM		0x3C
68 #define	CC2520_CMD_SXOSCON		0x40
69 #define	CC2520_CMD_STXCAL		0x41
70 #define	CC2520_CMD_SRXON		0x42
71 #define	CC2520_CMD_STXON		0x43
72 #define	CC2520_CMD_STXONCCA		0x44
73 #define	CC2520_CMD_SRFOFF		0x45
74 #define	CC2520_CMD_SXOSCOFF		0x46
75 #define	CC2520_CMD_SFLUSHRX		0x47
76 #define	CC2520_CMD_SFLUSHTX		0x48
77 #define	CC2520_CMD_SACK			0x49
78 #define	CC2520_CMD_SACKPEND		0x4A
79 #define	CC2520_CMD_SNACK		0x4B
80 #define	CC2520_CMD_SRXMASKBITSET	0x4C
81 #define	CC2520_CMD_SRXMASKBITCLR	0x4D
82 #define	CC2520_CMD_RXMASKAND		0x4E
83 #define	CC2520_CMD_RXMASKOR		0x4F
84 #define	CC2520_CMD_MEMCP		0x50
85 #define	CC2520_CMD_MEMCPR		0x52
86 #define	CC2520_CMD_MEMXCP		0x54
87 #define	CC2520_CMD_MEMXWR		0x56
88 #define	CC2520_CMD_BCLR			0x58
89 #define	CC2520_CMD_BSET			0x59
90 #define	CC2520_CMD_CTR_UCTR		0x60
91 #define	CC2520_CMD_CBCMAC		0x64
92 #define	CC2520_CMD_UCBCMAC		0x66
93 #define	CC2520_CMD_CCM			0x68
94 #define	CC2520_CMD_UCCM			0x6A
95 #define	CC2520_CMD_ECB			0x70
96 #define	CC2520_CMD_ECBO			0x72
97 #define	CC2520_CMD_ECBX			0x74
98 #define	CC2520_CMD_INC			0x78
99 #define	CC2520_CMD_ABORT		0x7F
100 #define	CC2520_CMD_REGISTER_READ	0x80
101 #define	CC2520_CMD_REGISTER_WRITE	0xC0
102 
103 /* status registers */
104 #define	CC2520_CHIPID			0x40
105 #define	CC2520_VERSION			0x42
106 #define	CC2520_EXTCLOCK			0x44
107 #define	CC2520_MDMCTRL0			0x46
108 #define	CC2520_MDMCTRL1			0x47
109 #define	CC2520_FREQEST			0x48
110 #define	CC2520_RXCTRL			0x4A
111 #define	CC2520_FSCTRL			0x4C
112 #define	CC2520_FSCAL0			0x4E
113 #define	CC2520_FSCAL1			0x4F
114 #define	CC2520_FSCAL2			0x50
115 #define	CC2520_FSCAL3			0x51
116 #define	CC2520_AGCCTRL0			0x52
117 #define	CC2520_AGCCTRL1			0x53
118 #define	CC2520_AGCCTRL2			0x54
119 #define	CC2520_AGCCTRL3			0x55
120 #define	CC2520_ADCTEST0			0x56
121 #define	CC2520_ADCTEST1			0x57
122 #define	CC2520_ADCTEST2			0x58
123 #define	CC2520_MDMTEST0			0x5A
124 #define	CC2520_MDMTEST1			0x5B
125 #define	CC2520_DACTEST0			0x5C
126 #define	CC2520_DACTEST1			0x5D
127 #define	CC2520_ATEST			0x5E
128 #define	CC2520_DACTEST2			0x5F
129 #define	CC2520_PTEST0			0x60
130 #define	CC2520_PTEST1			0x61
131 #define	CC2520_RESERVED			0x62
132 #define	CC2520_DPUBIST			0x7A
133 #define	CC2520_ACTBIST			0x7C
134 #define	CC2520_RAMBIST			0x7E
135 
136 /* frame registers */
137 #define	CC2520_FRMFILT0			0x00
138 #define	CC2520_FRMFILT1			0x01
139 #define	CC2520_SRCMATCH			0x02
140 #define	CC2520_SRCSHORTEN0		0x04
141 #define	CC2520_SRCSHORTEN1		0x05
142 #define	CC2520_SRCSHORTEN2		0x06
143 #define	CC2520_SRCEXTEN0		0x08
144 #define	CC2520_SRCEXTEN1		0x09
145 #define	CC2520_SRCEXTEN2		0x0A
146 #define	CC2520_FRMCTRL0			0x0C
147 #define	CC2520_FRMCTRL1			0x0D
148 #define	CC2520_RXENABLE0		0x0E
149 #define	CC2520_RXENABLE1		0x0F
150 #define	CC2520_EXCFLAG0			0x10
151 #define	CC2520_EXCFLAG1			0x11
152 #define	CC2520_EXCFLAG2			0x12
153 #define	CC2520_EXCMASKA0		0x14
154 #define	CC2520_EXCMASKA1		0x15
155 #define	CC2520_EXCMASKA2		0x16
156 #define	CC2520_EXCMASKB0		0x18
157 #define	CC2520_EXCMASKB1		0x19
158 #define	CC2520_EXCMASKB2		0x1A
159 #define	CC2520_EXCBINDX0		0x1C
160 #define	CC2520_EXCBINDX1		0x1D
161 #define	CC2520_EXCBINDY0		0x1E
162 #define	CC2520_EXCBINDY1		0x1F
163 #define	CC2520_GPIOCTRL0		0x20
164 #define	CC2520_GPIOCTRL1		0x21
165 #define	CC2520_GPIOCTRL2		0x22
166 #define	CC2520_GPIOCTRL3		0x23
167 #define	CC2520_GPIOCTRL4		0x24
168 #define	CC2520_GPIOCTRL5		0x25
169 #define	CC2520_GPIOPOLARITY		0x26
170 #define	CC2520_GPIOCTRL			0x28
171 #define	CC2520_DPUCON			0x2A
172 #define	CC2520_DPUSTAT			0x2C
173 #define	CC2520_FREQCTRL			0x2E
174 #define	CC2520_FREQTUNE			0x2F
175 #define	CC2520_TXPOWER			0x30
176 #define	CC2520_TXCTRL			0x31
177 #define	CC2520_FSMSTAT0			0x32
178 #define	CC2520_FSMSTAT1			0x33
179 #define	CC2520_FIFOPCTRL		0x34
180 #define	CC2520_FSMCTRL			0x35
181 #define	CC2520_CCACTRL0			0x36
182 #define	CC2520_CCACTRL1			0x37
183 #define	CC2520_RSSI			0x38
184 #define	CC2520_RSSISTAT			0x39
185 #define	CC2520_RXFIRST			0x3C
186 #define	CC2520_RXFIFOCNT		0x3E
187 #define	CC2520_TXFIFOCNT		0x3F
188 
189 /* CC2520_FRMFILT0 */
190 #define FRMFILT0_FRAME_FILTER_EN	BIT(0)
191 #define FRMFILT0_PAN_COORDINATOR	BIT(1)
192 
193 /* CC2520_FRMCTRL0 */
194 #define FRMCTRL0_AUTOACK		BIT(5)
195 #define FRMCTRL0_AUTOCRC		BIT(6)
196 
197 /* CC2520_FRMCTRL1 */
198 #define FRMCTRL1_SET_RXENMASK_ON_TX	BIT(0)
199 #define FRMCTRL1_IGNORE_TX_UNDERF	BIT(1)
200 
201 /* Driver private information */
202 struct cc2520_private {
203 	struct spi_device *spi;		/* SPI device structure */
204 	struct ieee802154_hw *hw;	/* IEEE-802.15.4 device */
205 	u8 *buf;			/* SPI TX/Rx data buffer */
206 	struct mutex buffer_mutex;	/* SPI buffer mutex */
207 	bool is_tx;			/* Flag for sync b/w Tx and Rx */
208 	bool amplified;			/* Flag for CC2591 */
209 	int fifo_pin;			/* FIFO GPIO pin number */
210 	struct work_struct fifop_irqwork;/* Workqueue for FIFOP */
211 	spinlock_t lock;		/* Lock for is_tx*/
212 	struct completion tx_complete;	/* Work completion for Tx */
213 	bool promiscuous;               /* Flag for promiscuous mode */
214 };
215 
216 /* Generic Functions */
217 static int
218 cc2520_cmd_strobe(struct cc2520_private *priv, u8 cmd)
219 {
220 	int ret;
221 	struct spi_message msg;
222 	struct spi_transfer xfer = {
223 		.len = 0,
224 		.tx_buf = priv->buf,
225 		.rx_buf = priv->buf,
226 	};
227 
228 	spi_message_init(&msg);
229 	spi_message_add_tail(&xfer, &msg);
230 
231 	mutex_lock(&priv->buffer_mutex);
232 	priv->buf[xfer.len++] = cmd;
233 	dev_vdbg(&priv->spi->dev,
234 		 "command strobe buf[0] = %02x\n",
235 		 priv->buf[0]);
236 
237 	ret = spi_sync(priv->spi, &msg);
238 	dev_vdbg(&priv->spi->dev,
239 		 "buf[0] = %02x\n", priv->buf[0]);
240 	mutex_unlock(&priv->buffer_mutex);
241 
242 	return ret;
243 }
244 
245 static int
246 cc2520_get_status(struct cc2520_private *priv, u8 *status)
247 {
248 	int ret;
249 	struct spi_message msg;
250 	struct spi_transfer xfer = {
251 		.len = 0,
252 		.tx_buf = priv->buf,
253 		.rx_buf = priv->buf,
254 	};
255 
256 	spi_message_init(&msg);
257 	spi_message_add_tail(&xfer, &msg);
258 
259 	mutex_lock(&priv->buffer_mutex);
260 	priv->buf[xfer.len++] = CC2520_CMD_SNOP;
261 	dev_vdbg(&priv->spi->dev,
262 		 "get status command buf[0] = %02x\n", priv->buf[0]);
263 
264 	ret = spi_sync(priv->spi, &msg);
265 	if (!ret)
266 		*status = priv->buf[0];
267 	dev_vdbg(&priv->spi->dev,
268 		 "buf[0] = %02x\n", priv->buf[0]);
269 	mutex_unlock(&priv->buffer_mutex);
270 
271 	return ret;
272 }
273 
274 static int
275 cc2520_write_register(struct cc2520_private *priv, u8 reg, u8 value)
276 {
277 	int status;
278 	struct spi_message msg;
279 	struct spi_transfer xfer = {
280 		.len = 0,
281 		.tx_buf = priv->buf,
282 		.rx_buf = priv->buf,
283 	};
284 
285 	spi_message_init(&msg);
286 	spi_message_add_tail(&xfer, &msg);
287 
288 	mutex_lock(&priv->buffer_mutex);
289 
290 	if (reg <= CC2520_FREG_MASK) {
291 		priv->buf[xfer.len++] = CC2520_CMD_REGISTER_WRITE | reg;
292 		priv->buf[xfer.len++] = value;
293 	} else {
294 		priv->buf[xfer.len++] = CC2520_CMD_MEMORY_WRITE;
295 		priv->buf[xfer.len++] = reg;
296 		priv->buf[xfer.len++] = value;
297 	}
298 	status = spi_sync(priv->spi, &msg);
299 	if (msg.status)
300 		status = msg.status;
301 
302 	mutex_unlock(&priv->buffer_mutex);
303 
304 	return status;
305 }
306 
307 static int
308 cc2520_write_ram(struct cc2520_private *priv, u16 reg, u8 len, u8 *data)
309 {
310 	int status;
311 	struct spi_message msg;
312 	struct spi_transfer xfer_head = {
313 		.len        = 0,
314 		.tx_buf        = priv->buf,
315 		.rx_buf        = priv->buf,
316 	};
317 
318 	struct spi_transfer xfer_buf = {
319 		.len = len,
320 		.tx_buf = data,
321 	};
322 
323 	mutex_lock(&priv->buffer_mutex);
324 	priv->buf[xfer_head.len++] = (CC2520_CMD_MEMORY_WRITE |
325 						((reg >> 8) & 0xff));
326 	priv->buf[xfer_head.len++] = reg & 0xff;
327 
328 	spi_message_init(&msg);
329 	spi_message_add_tail(&xfer_head, &msg);
330 	spi_message_add_tail(&xfer_buf, &msg);
331 
332 	status = spi_sync(priv->spi, &msg);
333 	dev_dbg(&priv->spi->dev, "spi status = %d\n", status);
334 	if (msg.status)
335 		status = msg.status;
336 
337 	mutex_unlock(&priv->buffer_mutex);
338 	return status;
339 }
340 
341 static int
342 cc2520_read_register(struct cc2520_private *priv, u8 reg, u8 *data)
343 {
344 	int status;
345 	struct spi_message msg;
346 	struct spi_transfer xfer1 = {
347 		.len = 0,
348 		.tx_buf = priv->buf,
349 		.rx_buf = priv->buf,
350 	};
351 
352 	struct spi_transfer xfer2 = {
353 		.len = 1,
354 		.rx_buf = data,
355 	};
356 
357 	spi_message_init(&msg);
358 	spi_message_add_tail(&xfer1, &msg);
359 	spi_message_add_tail(&xfer2, &msg);
360 
361 	mutex_lock(&priv->buffer_mutex);
362 	priv->buf[xfer1.len++] = CC2520_CMD_MEMORY_READ;
363 	priv->buf[xfer1.len++] = reg;
364 
365 	status = spi_sync(priv->spi, &msg);
366 	dev_dbg(&priv->spi->dev,
367 		"spi status = %d\n", status);
368 	if (msg.status)
369 		status = msg.status;
370 
371 	mutex_unlock(&priv->buffer_mutex);
372 
373 	return status;
374 }
375 
376 static int
377 cc2520_write_txfifo(struct cc2520_private *priv, u8 pkt_len, u8 *data, u8 len)
378 {
379 	int status;
380 
381 	/* length byte must include FCS even
382 	 * if it is calculated in the hardware
383 	 */
384 	int len_byte = pkt_len;
385 
386 	struct spi_message msg;
387 
388 	struct spi_transfer xfer_head = {
389 		.len = 0,
390 		.tx_buf = priv->buf,
391 		.rx_buf = priv->buf,
392 	};
393 	struct spi_transfer xfer_len = {
394 		.len = 1,
395 		.tx_buf = &len_byte,
396 	};
397 	struct spi_transfer xfer_buf = {
398 		.len = len,
399 		.tx_buf = data,
400 	};
401 
402 	spi_message_init(&msg);
403 	spi_message_add_tail(&xfer_head, &msg);
404 	spi_message_add_tail(&xfer_len, &msg);
405 	spi_message_add_tail(&xfer_buf, &msg);
406 
407 	mutex_lock(&priv->buffer_mutex);
408 	priv->buf[xfer_head.len++] = CC2520_CMD_TXBUF;
409 	dev_vdbg(&priv->spi->dev,
410 		 "TX_FIFO cmd buf[0] = %02x\n", priv->buf[0]);
411 
412 	status = spi_sync(priv->spi, &msg);
413 	dev_vdbg(&priv->spi->dev, "status = %d\n", status);
414 	if (msg.status)
415 		status = msg.status;
416 	dev_vdbg(&priv->spi->dev, "status = %d\n", status);
417 	dev_vdbg(&priv->spi->dev, "buf[0] = %02x\n", priv->buf[0]);
418 	mutex_unlock(&priv->buffer_mutex);
419 
420 	return status;
421 }
422 
423 static int
424 cc2520_read_rxfifo(struct cc2520_private *priv, u8 *data, u8 len)
425 {
426 	int status;
427 	struct spi_message msg;
428 
429 	struct spi_transfer xfer_head = {
430 		.len = 0,
431 		.tx_buf = priv->buf,
432 		.rx_buf = priv->buf,
433 	};
434 	struct spi_transfer xfer_buf = {
435 		.len = len,
436 		.rx_buf = data,
437 	};
438 
439 	spi_message_init(&msg);
440 	spi_message_add_tail(&xfer_head, &msg);
441 	spi_message_add_tail(&xfer_buf, &msg);
442 
443 	mutex_lock(&priv->buffer_mutex);
444 	priv->buf[xfer_head.len++] = CC2520_CMD_RXBUF;
445 
446 	dev_vdbg(&priv->spi->dev, "read rxfifo buf[0] = %02x\n", priv->buf[0]);
447 	dev_vdbg(&priv->spi->dev, "buf[1] = %02x\n", priv->buf[1]);
448 
449 	status = spi_sync(priv->spi, &msg);
450 	dev_vdbg(&priv->spi->dev, "status = %d\n", status);
451 	if (msg.status)
452 		status = msg.status;
453 	dev_vdbg(&priv->spi->dev, "status = %d\n", status);
454 	dev_vdbg(&priv->spi->dev,
455 		 "return status buf[0] = %02x\n", priv->buf[0]);
456 	dev_vdbg(&priv->spi->dev, "length buf[1] = %02x\n", priv->buf[1]);
457 
458 	mutex_unlock(&priv->buffer_mutex);
459 
460 	return status;
461 }
462 
463 static int cc2520_start(struct ieee802154_hw *hw)
464 {
465 	return cc2520_cmd_strobe(hw->priv, CC2520_CMD_SRXON);
466 }
467 
468 static void cc2520_stop(struct ieee802154_hw *hw)
469 {
470 	cc2520_cmd_strobe(hw->priv, CC2520_CMD_SRFOFF);
471 }
472 
473 static int
474 cc2520_tx(struct ieee802154_hw *hw, struct sk_buff *skb)
475 {
476 	struct cc2520_private *priv = hw->priv;
477 	unsigned long flags;
478 	int rc;
479 	u8 status = 0;
480 	u8 pkt_len;
481 
482 	/* In promiscuous mode we disable AUTOCRC so we can get the raw CRC
483 	 * values on RX. This means we need to manually add the CRC on TX.
484 	 */
485 	if (priv->promiscuous) {
486 		u16 crc = crc_ccitt(0, skb->data, skb->len);
487 
488 		put_unaligned_le16(crc, skb_put(skb, 2));
489 		pkt_len = skb->len;
490 	} else {
491 		pkt_len = skb->len + 2;
492 	}
493 
494 	rc = cc2520_cmd_strobe(priv, CC2520_CMD_SFLUSHTX);
495 	if (rc)
496 		goto err_tx;
497 
498 	rc = cc2520_write_txfifo(priv, pkt_len, skb->data, skb->len);
499 	if (rc)
500 		goto err_tx;
501 
502 	rc = cc2520_get_status(priv, &status);
503 	if (rc)
504 		goto err_tx;
505 
506 	if (status & CC2520_STATUS_TX_UNDERFLOW) {
507 		dev_err(&priv->spi->dev, "cc2520 tx underflow exception\n");
508 		goto err_tx;
509 	}
510 
511 	spin_lock_irqsave(&priv->lock, flags);
512 	WARN_ON(priv->is_tx);
513 	priv->is_tx = 1;
514 	spin_unlock_irqrestore(&priv->lock, flags);
515 
516 	rc = cc2520_cmd_strobe(priv, CC2520_CMD_STXONCCA);
517 	if (rc)
518 		goto err;
519 
520 	rc = wait_for_completion_interruptible(&priv->tx_complete);
521 	if (rc < 0)
522 		goto err;
523 
524 	cc2520_cmd_strobe(priv, CC2520_CMD_SFLUSHTX);
525 	cc2520_cmd_strobe(priv, CC2520_CMD_SRXON);
526 
527 	return rc;
528 err:
529 	spin_lock_irqsave(&priv->lock, flags);
530 	priv->is_tx = 0;
531 	spin_unlock_irqrestore(&priv->lock, flags);
532 err_tx:
533 	return rc;
534 }
535 
536 static int cc2520_rx(struct cc2520_private *priv)
537 {
538 	u8 len = 0, lqi = 0, bytes = 1;
539 	struct sk_buff *skb;
540 
541 	/* Read single length byte from the radio. */
542 	cc2520_read_rxfifo(priv, &len, bytes);
543 
544 	if (!ieee802154_is_valid_psdu_len(len)) {
545 		/* Corrupted frame received, clear frame buffer by
546 		 * reading entire buffer.
547 		 */
548 		dev_dbg(&priv->spi->dev, "corrupted frame received\n");
549 		len = IEEE802154_MTU;
550 	}
551 
552 	skb = dev_alloc_skb(len);
553 	if (!skb)
554 		return -ENOMEM;
555 
556 	if (cc2520_read_rxfifo(priv, skb_put(skb, len), len)) {
557 		dev_dbg(&priv->spi->dev, "frame reception failed\n");
558 		kfree_skb(skb);
559 		return -EINVAL;
560 	}
561 
562 	/* In promiscuous mode, we configure the radio to include the
563 	 * CRC (AUTOCRC==0) and we pass on the packet unconditionally. If not
564 	 * in promiscuous mode, we check the CRC here, but leave the
565 	 * RSSI/LQI/CRC_OK bytes as they will get removed in the mac layer.
566 	 */
567 	if (!priv->promiscuous) {
568 		bool crc_ok;
569 
570 		/* Check if the CRC is valid. With AUTOCRC set, the most
571 		 * significant bit of the last byte returned from the CC2520
572 		 * is CRC_OK flag. See section 20.3.4 of the datasheet.
573 		 */
574 		crc_ok = skb->data[len - 1] & BIT(7);
575 
576 		/* If we failed CRC drop the packet in the driver layer. */
577 		if (!crc_ok) {
578 			dev_dbg(&priv->spi->dev, "CRC check failed\n");
579 			kfree_skb(skb);
580 			return -EINVAL;
581 		}
582 
583 		/* To calculate LQI, the lower 7 bits of the last byte (the
584 		 * correlation value provided by the radio) must be scaled to
585 		 * the range 0-255. According to section 20.6, the correlation
586 		 * value ranges from 50-110. Ideally this would be calibrated
587 		 * per hardware design, but we use roughly the datasheet values
588 		 * to get close enough while avoiding floating point.
589 		 */
590 		lqi = skb->data[len - 1] & 0x7f;
591 		if (lqi < 50)
592 			lqi = 50;
593 		else if (lqi > 113)
594 			lqi = 113;
595 		lqi = (lqi - 50) * 4;
596 	}
597 
598 	ieee802154_rx_irqsafe(priv->hw, skb, lqi);
599 
600 	dev_vdbg(&priv->spi->dev, "RXFIFO: %x %x\n", len, lqi);
601 
602 	return 0;
603 }
604 
605 static int
606 cc2520_ed(struct ieee802154_hw *hw, u8 *level)
607 {
608 	struct cc2520_private *priv = hw->priv;
609 	u8 status = 0xff;
610 	u8 rssi;
611 	int ret;
612 
613 	ret = cc2520_read_register(priv, CC2520_RSSISTAT, &status);
614 	if (ret)
615 		return ret;
616 
617 	if (status != RSSI_VALID)
618 		return -EINVAL;
619 
620 	ret = cc2520_read_register(priv, CC2520_RSSI, &rssi);
621 	if (ret)
622 		return ret;
623 
624 	/* level = RSSI(rssi) - OFFSET [dBm] : offset is 76dBm */
625 	*level = rssi - RSSI_OFFSET;
626 
627 	return 0;
628 }
629 
630 static int
631 cc2520_set_channel(struct ieee802154_hw *hw, u8 page, u8 channel)
632 {
633 	struct cc2520_private *priv = hw->priv;
634 	int ret;
635 
636 	dev_dbg(&priv->spi->dev, "trying to set channel\n");
637 
638 	WARN_ON(page != 0);
639 	WARN_ON(channel < CC2520_MINCHANNEL);
640 	WARN_ON(channel > CC2520_MAXCHANNEL);
641 
642 	ret = cc2520_write_register(priv, CC2520_FREQCTRL,
643 				    11 + 5 * (channel - 11));
644 
645 	return ret;
646 }
647 
648 static int
649 cc2520_filter(struct ieee802154_hw *hw,
650 	      struct ieee802154_hw_addr_filt *filt, unsigned long changed)
651 {
652 	struct cc2520_private *priv = hw->priv;
653 	int ret = 0;
654 
655 	if (changed & IEEE802154_AFILT_PANID_CHANGED) {
656 		u16 panid = le16_to_cpu(filt->pan_id);
657 
658 		dev_vdbg(&priv->spi->dev, "%s called for pan id\n", __func__);
659 		ret = cc2520_write_ram(priv, CC2520RAM_PANID,
660 				       sizeof(panid), (u8 *)&panid);
661 	}
662 
663 	if (changed & IEEE802154_AFILT_IEEEADDR_CHANGED) {
664 		dev_vdbg(&priv->spi->dev,
665 			 "%s called for IEEE addr\n", __func__);
666 		ret = cc2520_write_ram(priv, CC2520RAM_IEEEADDR,
667 				       sizeof(filt->ieee_addr),
668 				       (u8 *)&filt->ieee_addr);
669 	}
670 
671 	if (changed & IEEE802154_AFILT_SADDR_CHANGED) {
672 		u16 addr = le16_to_cpu(filt->short_addr);
673 
674 		dev_vdbg(&priv->spi->dev, "%s called for saddr\n", __func__);
675 		ret = cc2520_write_ram(priv, CC2520RAM_SHORTADDR,
676 				       sizeof(addr), (u8 *)&addr);
677 	}
678 
679 	if (changed & IEEE802154_AFILT_PANC_CHANGED) {
680 		u8 frmfilt0;
681 
682 		dev_vdbg(&priv->spi->dev,
683 			 "%s called for panc change\n", __func__);
684 
685 		cc2520_read_register(priv, CC2520_FRMFILT0, &frmfilt0);
686 
687 		if (filt->pan_coord)
688 			frmfilt0 |= FRMFILT0_PAN_COORDINATOR;
689 		else
690 			frmfilt0 &= ~FRMFILT0_PAN_COORDINATOR;
691 
692 		ret = cc2520_write_register(priv, CC2520_FRMFILT0, frmfilt0);
693 	}
694 
695 	return ret;
696 }
697 
698 static inline int cc2520_set_tx_power(struct cc2520_private *priv, s32 mbm)
699 {
700 	u8 power;
701 
702 	switch (mbm) {
703 	case 500:
704 		power = 0xF7;
705 		break;
706 	case 300:
707 		power = 0xF2;
708 		break;
709 	case 200:
710 		power = 0xAB;
711 		break;
712 	case 100:
713 		power = 0x13;
714 		break;
715 	case 0:
716 		power = 0x32;
717 		break;
718 	case -200:
719 		power = 0x81;
720 		break;
721 	case -400:
722 		power = 0x88;
723 		break;
724 	case -700:
725 		power = 0x2C;
726 		break;
727 	case -1800:
728 		power = 0x03;
729 		break;
730 	default:
731 		return -EINVAL;
732 	}
733 
734 	return cc2520_write_register(priv, CC2520_TXPOWER, power);
735 }
736 
737 static inline int cc2520_cc2591_set_tx_power(struct cc2520_private *priv,
738 					     s32 mbm)
739 {
740 	u8 power;
741 
742 	switch (mbm) {
743 	case 1700:
744 		power = 0xF9;
745 		break;
746 	case 1600:
747 		power = 0xF0;
748 		break;
749 	case 1400:
750 		power = 0xA0;
751 		break;
752 	case 1100:
753 		power = 0x2C;
754 		break;
755 	case -100:
756 		power = 0x03;
757 		break;
758 	case -800:
759 		power = 0x01;
760 		break;
761 	default:
762 		return -EINVAL;
763 	}
764 
765 	return cc2520_write_register(priv, CC2520_TXPOWER, power);
766 }
767 
768 #define CC2520_MAX_TX_POWERS 0x8
769 static const s32 cc2520_powers[CC2520_MAX_TX_POWERS + 1] = {
770 	500, 300, 200, 100, 0, -200, -400, -700, -1800,
771 };
772 
773 #define CC2520_CC2591_MAX_TX_POWERS 0x5
774 static const s32 cc2520_cc2591_powers[CC2520_CC2591_MAX_TX_POWERS + 1] = {
775 	1700, 1600, 1400, 1100, -100, -800,
776 };
777 
778 static int
779 cc2520_set_txpower(struct ieee802154_hw *hw, s32 mbm)
780 {
781 	struct cc2520_private *priv = hw->priv;
782 
783 	if (!priv->amplified)
784 		return cc2520_set_tx_power(priv, mbm);
785 
786 	return cc2520_cc2591_set_tx_power(priv, mbm);
787 }
788 
789 static int
790 cc2520_set_promiscuous_mode(struct ieee802154_hw *hw, bool on)
791 {
792 	struct cc2520_private *priv = hw->priv;
793 	u8 frmfilt0;
794 
795 	dev_dbg(&priv->spi->dev, "%s : mode %d\n", __func__, on);
796 
797 	priv->promiscuous = on;
798 
799 	cc2520_read_register(priv, CC2520_FRMFILT0, &frmfilt0);
800 
801 	if (on) {
802 		/* Disable automatic ACK, automatic CRC, and frame filtering. */
803 		cc2520_write_register(priv, CC2520_FRMCTRL0, 0);
804 		frmfilt0 &= ~FRMFILT0_FRAME_FILTER_EN;
805 	} else {
806 		cc2520_write_register(priv, CC2520_FRMCTRL0, FRMCTRL0_AUTOACK |
807 							     FRMCTRL0_AUTOCRC);
808 		frmfilt0 |= FRMFILT0_FRAME_FILTER_EN;
809 	}
810 	return cc2520_write_register(priv, CC2520_FRMFILT0, frmfilt0);
811 }
812 
813 static const struct ieee802154_ops cc2520_ops = {
814 	.owner = THIS_MODULE,
815 	.start = cc2520_start,
816 	.stop = cc2520_stop,
817 	.xmit_sync = cc2520_tx,
818 	.ed = cc2520_ed,
819 	.set_channel = cc2520_set_channel,
820 	.set_hw_addr_filt = cc2520_filter,
821 	.set_txpower = cc2520_set_txpower,
822 	.set_promiscuous_mode = cc2520_set_promiscuous_mode,
823 };
824 
825 static int cc2520_register(struct cc2520_private *priv)
826 {
827 	int ret = -ENOMEM;
828 
829 	priv->hw = ieee802154_alloc_hw(sizeof(*priv), &cc2520_ops);
830 	if (!priv->hw)
831 		goto err_ret;
832 
833 	priv->hw->priv = priv;
834 	priv->hw->parent = &priv->spi->dev;
835 	priv->hw->extra_tx_headroom = 0;
836 	ieee802154_random_extended_addr(&priv->hw->phy->perm_extended_addr);
837 
838 	/* We do support only 2.4 Ghz */
839 	priv->hw->phy->supported.channels[0] = 0x7FFF800;
840 	priv->hw->flags = IEEE802154_HW_TX_OMIT_CKSUM | IEEE802154_HW_AFILT |
841 			  IEEE802154_HW_PROMISCUOUS;
842 
843 	priv->hw->phy->flags = WPAN_PHY_FLAG_TXPOWER;
844 
845 	if (!priv->amplified) {
846 		priv->hw->phy->supported.tx_powers = cc2520_powers;
847 		priv->hw->phy->supported.tx_powers_size = ARRAY_SIZE(cc2520_powers);
848 		priv->hw->phy->transmit_power = priv->hw->phy->supported.tx_powers[4];
849 	} else {
850 		priv->hw->phy->supported.tx_powers = cc2520_cc2591_powers;
851 		priv->hw->phy->supported.tx_powers_size = ARRAY_SIZE(cc2520_cc2591_powers);
852 		priv->hw->phy->transmit_power = priv->hw->phy->supported.tx_powers[0];
853 	}
854 
855 	priv->hw->phy->current_channel = 11;
856 
857 	dev_vdbg(&priv->spi->dev, "registered cc2520\n");
858 	ret = ieee802154_register_hw(priv->hw);
859 	if (ret)
860 		goto err_free_device;
861 
862 	return 0;
863 
864 err_free_device:
865 	ieee802154_free_hw(priv->hw);
866 err_ret:
867 	return ret;
868 }
869 
870 static void cc2520_fifop_irqwork(struct work_struct *work)
871 {
872 	struct cc2520_private *priv
873 		= container_of(work, struct cc2520_private, fifop_irqwork);
874 
875 	dev_dbg(&priv->spi->dev, "fifop interrupt received\n");
876 
877 	if (gpio_get_value(priv->fifo_pin))
878 		cc2520_rx(priv);
879 	else
880 		dev_dbg(&priv->spi->dev, "rxfifo overflow\n");
881 
882 	cc2520_cmd_strobe(priv, CC2520_CMD_SFLUSHRX);
883 	cc2520_cmd_strobe(priv, CC2520_CMD_SFLUSHRX);
884 }
885 
886 static irqreturn_t cc2520_fifop_isr(int irq, void *data)
887 {
888 	struct cc2520_private *priv = data;
889 
890 	schedule_work(&priv->fifop_irqwork);
891 
892 	return IRQ_HANDLED;
893 }
894 
895 static irqreturn_t cc2520_sfd_isr(int irq, void *data)
896 {
897 	struct cc2520_private *priv = data;
898 	unsigned long flags;
899 
900 	spin_lock_irqsave(&priv->lock, flags);
901 	if (priv->is_tx) {
902 		priv->is_tx = 0;
903 		spin_unlock_irqrestore(&priv->lock, flags);
904 		dev_dbg(&priv->spi->dev, "SFD for TX\n");
905 		complete(&priv->tx_complete);
906 	} else {
907 		spin_unlock_irqrestore(&priv->lock, flags);
908 		dev_dbg(&priv->spi->dev, "SFD for RX\n");
909 	}
910 
911 	return IRQ_HANDLED;
912 }
913 
914 static int cc2520_get_platform_data(struct spi_device *spi,
915 				    struct cc2520_platform_data *pdata)
916 {
917 	struct device_node *np = spi->dev.of_node;
918 	struct cc2520_private *priv = spi_get_drvdata(spi);
919 
920 	if (!np) {
921 		struct cc2520_platform_data *spi_pdata = spi->dev.platform_data;
922 
923 		if (!spi_pdata)
924 			return -ENOENT;
925 		*pdata = *spi_pdata;
926 		priv->fifo_pin = pdata->fifo;
927 		return 0;
928 	}
929 
930 	pdata->fifo = of_get_named_gpio(np, "fifo-gpio", 0);
931 	priv->fifo_pin = pdata->fifo;
932 
933 	pdata->fifop = of_get_named_gpio(np, "fifop-gpio", 0);
934 
935 	pdata->sfd = of_get_named_gpio(np, "sfd-gpio", 0);
936 	pdata->cca = of_get_named_gpio(np, "cca-gpio", 0);
937 	pdata->vreg = of_get_named_gpio(np, "vreg-gpio", 0);
938 	pdata->reset = of_get_named_gpio(np, "reset-gpio", 0);
939 
940 	/* CC2591 front end for CC2520 */
941 	if (of_property_read_bool(np, "amplified"))
942 		priv->amplified = true;
943 
944 	return 0;
945 }
946 
947 static int cc2520_hw_init(struct cc2520_private *priv)
948 {
949 	u8 status = 0, state = 0xff;
950 	int ret;
951 	int timeout = 100;
952 	struct cc2520_platform_data pdata;
953 
954 	ret = cc2520_get_platform_data(priv->spi, &pdata);
955 	if (ret)
956 		goto err_ret;
957 
958 	ret = cc2520_read_register(priv, CC2520_FSMSTAT1, &state);
959 	if (ret)
960 		goto err_ret;
961 
962 	if (state != STATE_IDLE)
963 		return -EINVAL;
964 
965 	do {
966 		ret = cc2520_get_status(priv, &status);
967 		if (ret)
968 			goto err_ret;
969 
970 		if (timeout-- <= 0) {
971 			dev_err(&priv->spi->dev, "oscillator start failed!\n");
972 			return ret;
973 		}
974 		udelay(1);
975 	} while (!(status & CC2520_STATUS_XOSC32M_STABLE));
976 
977 	dev_vdbg(&priv->spi->dev, "oscillator brought up\n");
978 
979 	/* If the CC2520 is connected to a CC2591 amplifier, we must both
980 	 * configure GPIOs on the CC2520 to correctly configure the CC2591
981 	 * and change a couple settings of the CC2520 to work with the
982 	 * amplifier. See section 8 page 17 of TI application note AN065.
983 	 * http://www.ti.com/lit/an/swra229a/swra229a.pdf
984 	 */
985 	if (priv->amplified) {
986 		ret = cc2520_write_register(priv, CC2520_AGCCTRL1, 0x16);
987 		if (ret)
988 			goto err_ret;
989 
990 		ret = cc2520_write_register(priv, CC2520_GPIOCTRL0, 0x46);
991 		if (ret)
992 			goto err_ret;
993 
994 		ret = cc2520_write_register(priv, CC2520_GPIOCTRL5, 0x47);
995 		if (ret)
996 			goto err_ret;
997 
998 		ret = cc2520_write_register(priv, CC2520_GPIOPOLARITY, 0x1e);
999 		if (ret)
1000 			goto err_ret;
1001 
1002 		ret = cc2520_write_register(priv, CC2520_TXCTRL, 0xc1);
1003 		if (ret)
1004 			goto err_ret;
1005 	} else {
1006 		ret = cc2520_write_register(priv, CC2520_AGCCTRL1, 0x11);
1007 		if (ret)
1008 			goto err_ret;
1009 	}
1010 
1011 	/* Registers default value: section 28.1 in Datasheet */
1012 
1013 	/* Set the CCA threshold to -50 dBm. This seems to have been copied
1014 	 * from the TinyOS CC2520 driver and is much higher than the -84 dBm
1015 	 * threshold suggested in the datasheet.
1016 	 */
1017 	ret = cc2520_write_register(priv, CC2520_CCACTRL0, 0x1A);
1018 	if (ret)
1019 		goto err_ret;
1020 
1021 	ret = cc2520_write_register(priv, CC2520_MDMCTRL0, 0x85);
1022 	if (ret)
1023 		goto err_ret;
1024 
1025 	ret = cc2520_write_register(priv, CC2520_MDMCTRL1, 0x14);
1026 	if (ret)
1027 		goto err_ret;
1028 
1029 	ret = cc2520_write_register(priv, CC2520_RXCTRL, 0x3f);
1030 	if (ret)
1031 		goto err_ret;
1032 
1033 	ret = cc2520_write_register(priv, CC2520_FSCTRL, 0x5a);
1034 	if (ret)
1035 		goto err_ret;
1036 
1037 	ret = cc2520_write_register(priv, CC2520_FSCAL1, 0x2b);
1038 	if (ret)
1039 		goto err_ret;
1040 
1041 	ret = cc2520_write_register(priv, CC2520_ADCTEST0, 0x10);
1042 	if (ret)
1043 		goto err_ret;
1044 
1045 	ret = cc2520_write_register(priv, CC2520_ADCTEST1, 0x0e);
1046 	if (ret)
1047 		goto err_ret;
1048 
1049 	ret = cc2520_write_register(priv, CC2520_ADCTEST2, 0x03);
1050 	if (ret)
1051 		goto err_ret;
1052 
1053 	/* Configure registers correctly for this driver. */
1054 	ret = cc2520_write_register(priv, CC2520_FRMCTRL1,
1055 				    FRMCTRL1_SET_RXENMASK_ON_TX |
1056 				    FRMCTRL1_IGNORE_TX_UNDERF);
1057 	if (ret)
1058 		goto err_ret;
1059 
1060 	ret = cc2520_write_register(priv, CC2520_FIFOPCTRL, 127);
1061 	if (ret)
1062 		goto err_ret;
1063 
1064 	return 0;
1065 
1066 err_ret:
1067 	return ret;
1068 }
1069 
1070 static int cc2520_probe(struct spi_device *spi)
1071 {
1072 	struct cc2520_private *priv;
1073 	struct cc2520_platform_data pdata;
1074 	int ret;
1075 
1076 	priv = devm_kzalloc(&spi->dev, sizeof(*priv), GFP_KERNEL);
1077 	if (!priv)
1078 		return -ENOMEM;
1079 
1080 	spi_set_drvdata(spi, priv);
1081 
1082 	ret = cc2520_get_platform_data(spi, &pdata);
1083 	if (ret < 0) {
1084 		dev_err(&spi->dev, "no platform data\n");
1085 		return -EINVAL;
1086 	}
1087 
1088 	priv->spi = spi;
1089 
1090 	priv->buf = devm_kzalloc(&spi->dev,
1091 				 SPI_COMMAND_BUFFER, GFP_KERNEL);
1092 	if (!priv->buf)
1093 		return -ENOMEM;
1094 
1095 	mutex_init(&priv->buffer_mutex);
1096 	INIT_WORK(&priv->fifop_irqwork, cc2520_fifop_irqwork);
1097 	spin_lock_init(&priv->lock);
1098 	init_completion(&priv->tx_complete);
1099 
1100 	/* Assumption that CC2591 is not connected */
1101 	priv->amplified = false;
1102 
1103 	/* Request all the gpio's */
1104 	if (!gpio_is_valid(pdata.fifo)) {
1105 		dev_err(&spi->dev, "fifo gpio is not valid\n");
1106 		ret = -EINVAL;
1107 		goto err_hw_init;
1108 	}
1109 
1110 	ret = devm_gpio_request_one(&spi->dev, pdata.fifo,
1111 				    GPIOF_IN, "fifo");
1112 	if (ret)
1113 		goto err_hw_init;
1114 
1115 	if (!gpio_is_valid(pdata.cca)) {
1116 		dev_err(&spi->dev, "cca gpio is not valid\n");
1117 		ret = -EINVAL;
1118 		goto err_hw_init;
1119 	}
1120 
1121 	ret = devm_gpio_request_one(&spi->dev, pdata.cca,
1122 				    GPIOF_IN, "cca");
1123 	if (ret)
1124 		goto err_hw_init;
1125 
1126 	if (!gpio_is_valid(pdata.fifop)) {
1127 		dev_err(&spi->dev, "fifop gpio is not valid\n");
1128 		ret = -EINVAL;
1129 		goto err_hw_init;
1130 	}
1131 
1132 	ret = devm_gpio_request_one(&spi->dev, pdata.fifop,
1133 				    GPIOF_IN, "fifop");
1134 	if (ret)
1135 		goto err_hw_init;
1136 
1137 	if (!gpio_is_valid(pdata.sfd)) {
1138 		dev_err(&spi->dev, "sfd gpio is not valid\n");
1139 		ret = -EINVAL;
1140 		goto err_hw_init;
1141 	}
1142 
1143 	ret = devm_gpio_request_one(&spi->dev, pdata.sfd,
1144 				    GPIOF_IN, "sfd");
1145 	if (ret)
1146 		goto err_hw_init;
1147 
1148 	if (!gpio_is_valid(pdata.reset)) {
1149 		dev_err(&spi->dev, "reset gpio is not valid\n");
1150 		ret = -EINVAL;
1151 		goto err_hw_init;
1152 	}
1153 
1154 	ret = devm_gpio_request_one(&spi->dev, pdata.reset,
1155 				    GPIOF_OUT_INIT_LOW, "reset");
1156 	if (ret)
1157 		goto err_hw_init;
1158 
1159 	if (!gpio_is_valid(pdata.vreg)) {
1160 		dev_err(&spi->dev, "vreg gpio is not valid\n");
1161 		ret = -EINVAL;
1162 		goto err_hw_init;
1163 	}
1164 
1165 	ret = devm_gpio_request_one(&spi->dev, pdata.vreg,
1166 				    GPIOF_OUT_INIT_LOW, "vreg");
1167 	if (ret)
1168 		goto err_hw_init;
1169 
1170 	gpio_set_value(pdata.vreg, HIGH);
1171 	usleep_range(100, 150);
1172 
1173 	gpio_set_value(pdata.reset, HIGH);
1174 	usleep_range(200, 250);
1175 
1176 	ret = cc2520_hw_init(priv);
1177 	if (ret)
1178 		goto err_hw_init;
1179 
1180 	/* Set up fifop interrupt */
1181 	ret = devm_request_irq(&spi->dev,
1182 			       gpio_to_irq(pdata.fifop),
1183 			       cc2520_fifop_isr,
1184 			       IRQF_TRIGGER_RISING,
1185 			       dev_name(&spi->dev),
1186 			       priv);
1187 	if (ret) {
1188 		dev_err(&spi->dev, "could not get fifop irq\n");
1189 		goto err_hw_init;
1190 	}
1191 
1192 	/* Set up sfd interrupt */
1193 	ret = devm_request_irq(&spi->dev,
1194 			       gpio_to_irq(pdata.sfd),
1195 			       cc2520_sfd_isr,
1196 			       IRQF_TRIGGER_FALLING,
1197 			       dev_name(&spi->dev),
1198 			       priv);
1199 	if (ret) {
1200 		dev_err(&spi->dev, "could not get sfd irq\n");
1201 		goto err_hw_init;
1202 	}
1203 
1204 	ret = cc2520_register(priv);
1205 	if (ret)
1206 		goto err_hw_init;
1207 
1208 	return 0;
1209 
1210 err_hw_init:
1211 	mutex_destroy(&priv->buffer_mutex);
1212 	flush_work(&priv->fifop_irqwork);
1213 	return ret;
1214 }
1215 
1216 static int cc2520_remove(struct spi_device *spi)
1217 {
1218 	struct cc2520_private *priv = spi_get_drvdata(spi);
1219 
1220 	mutex_destroy(&priv->buffer_mutex);
1221 	flush_work(&priv->fifop_irqwork);
1222 
1223 	ieee802154_unregister_hw(priv->hw);
1224 	ieee802154_free_hw(priv->hw);
1225 
1226 	return 0;
1227 }
1228 
1229 static const struct spi_device_id cc2520_ids[] = {
1230 	{"cc2520", },
1231 	{},
1232 };
1233 MODULE_DEVICE_TABLE(spi, cc2520_ids);
1234 
1235 static const struct of_device_id cc2520_of_ids[] = {
1236 	{.compatible = "ti,cc2520", },
1237 	{},
1238 };
1239 MODULE_DEVICE_TABLE(of, cc2520_of_ids);
1240 
1241 /* SPI driver structure */
1242 static struct spi_driver cc2520_driver = {
1243 	.driver = {
1244 		.name = "cc2520",
1245 		.of_match_table = of_match_ptr(cc2520_of_ids),
1246 	},
1247 	.id_table = cc2520_ids,
1248 	.probe = cc2520_probe,
1249 	.remove = cc2520_remove,
1250 };
1251 module_spi_driver(cc2520_driver);
1252 
1253 MODULE_AUTHOR("Varka Bhadram <varkab@cdac.in>");
1254 MODULE_DESCRIPTION("CC2520 Transceiver Driver");
1255 MODULE_LICENSE("GPL v2");
1256