1 // SPDX-License-Identifier: GPL-2.0-only
2 //
3 // Codec driver for Microsemi ZL38060 Connected Home Audio Processor.
4 //
5 // Copyright(c) 2020 Sven Van Asbroeck
6
7 // The ZL38060 is very flexible and configurable. This driver implements only a
8 // tiny subset of the chip's possible configurations:
9 //
10 // - DSP block bypassed: DAI routed straight to DACs
11 // microphone routed straight to DAI
12 // - chip's internal clock is driven by a 12 MHz external crystal
13 // - chip's DAI connected to CPU is I2S, and bit + frame clock master
14 // - chip must be strapped for "host boot": in this mode, firmware will be
15 // provided by this driver.
16
17 #include <linux/gpio/consumer.h>
18 #include <linux/gpio/driver.h>
19 #include <linux/property.h>
20 #include <linux/spi/spi.h>
21 #include <linux/regmap.h>
22 #include <linux/module.h>
23 #include <linux/ihex.h>
24
25 #include <sound/pcm_params.h>
26 #include <sound/core.h>
27 #include <sound/pcm.h>
28 #include <sound/soc.h>
29
30 #define DRV_NAME "zl38060"
31
32 #define ZL38_RATES (SNDRV_PCM_RATE_8000 |\
33 SNDRV_PCM_RATE_16000 |\
34 SNDRV_PCM_RATE_48000)
35 #define ZL38_FORMATS SNDRV_PCM_FMTBIT_S16_LE
36
37 #define HBI_FIRMWARE_PAGE 0xFF
38 #define ZL38_MAX_RAW_XFER 0x100
39
40 #define REG_TDMA_CFG_CLK 0x0262
41 #define CFG_CLK_PCLK_SHIFT 4
42 #define CFG_CLK_PCLK_MASK (0x7ff << CFG_CLK_PCLK_SHIFT)
43 #define CFG_CLK_PCLK(bits) ((bits - 1) << CFG_CLK_PCLK_SHIFT)
44 #define CFG_CLK_MASTER BIT(15)
45 #define CFG_CLK_FSRATE_MASK 0x7
46 #define CFG_CLK_FSRATE_8KHZ 0x1
47 #define CFG_CLK_FSRATE_16KHZ 0x2
48 #define CFG_CLK_FSRATE_48KHZ 0x6
49
50 #define REG_CLK_CFG 0x0016
51 #define CLK_CFG_SOURCE_XTAL BIT(15)
52
53 #define REG_CLK_STATUS 0x0014
54 #define CLK_STATUS_HWRST BIT(0)
55
56 #define REG_PARAM_RESULT 0x0034
57 #define PARAM_RESULT_READY 0xD3D3
58
59 #define REG_PG255_BASE_HI 0x000C
60 #define REG_PG255_OFFS(addr) ((HBI_FIRMWARE_PAGE << 8) | (addr & 0xFF))
61 #define REG_FWR_EXEC 0x012C
62
63 #define REG_CMD 0x0032
64 #define REG_HW_REV 0x0020
65 #define REG_FW_PROD 0x0022
66 #define REG_FW_REV 0x0024
67
68 #define REG_SEMA_FLAGS 0x0006
69 #define SEMA_FLAGS_BOOT_CMD BIT(0)
70 #define SEMA_FLAGS_APP_REBOOT BIT(1)
71
72 #define REG_HW_REV 0x0020
73 #define REG_FW_PROD 0x0022
74 #define REG_FW_REV 0x0024
75 #define REG_GPIO_DIR 0x02DC
76 #define REG_GPIO_DAT 0x02DA
77
78 #define BOOTCMD_LOAD_COMPLETE 0x000D
79 #define BOOTCMD_FW_GO 0x0008
80
81 #define FIRMWARE_MAJOR 2
82 #define FIRMWARE_MINOR 2
83
84 struct zl38_codec_priv {
85 struct device *dev;
86 struct regmap *regmap;
87 bool is_stream_in_use[2];
88 struct gpio_chip *gpio_chip;
89 };
90
zl38_fw_issue_command(struct regmap * regmap,u16 cmd)91 static int zl38_fw_issue_command(struct regmap *regmap, u16 cmd)
92 {
93 unsigned int val;
94 int err;
95
96 err = regmap_read_poll_timeout(regmap, REG_SEMA_FLAGS, val,
97 !(val & SEMA_FLAGS_BOOT_CMD), 10000,
98 10000 * 100);
99 if (err)
100 return err;
101 err = regmap_write(regmap, REG_CMD, cmd);
102 if (err)
103 return err;
104 err = regmap_update_bits(regmap, REG_SEMA_FLAGS, SEMA_FLAGS_BOOT_CMD,
105 SEMA_FLAGS_BOOT_CMD);
106 if (err)
107 return err;
108
109 return regmap_read_poll_timeout(regmap, REG_CMD, val, !val, 10000,
110 10000 * 100);
111 }
112
zl38_fw_go(struct regmap * regmap)113 static int zl38_fw_go(struct regmap *regmap)
114 {
115 int err;
116
117 err = zl38_fw_issue_command(regmap, BOOTCMD_LOAD_COMPLETE);
118 if (err)
119 return err;
120
121 return zl38_fw_issue_command(regmap, BOOTCMD_FW_GO);
122 }
123
zl38_fw_enter_boot_mode(struct regmap * regmap)124 static int zl38_fw_enter_boot_mode(struct regmap *regmap)
125 {
126 unsigned int val;
127 int err;
128
129 err = regmap_update_bits(regmap, REG_CLK_STATUS, CLK_STATUS_HWRST,
130 CLK_STATUS_HWRST);
131 if (err)
132 return err;
133
134 return regmap_read_poll_timeout(regmap, REG_PARAM_RESULT, val,
135 val == PARAM_RESULT_READY, 1000, 50000);
136 }
137
138 static int
zl38_fw_send_data(struct regmap * regmap,u32 addr,const void * data,u16 len)139 zl38_fw_send_data(struct regmap *regmap, u32 addr, const void *data, u16 len)
140 {
141 __be32 addr_base = cpu_to_be32(addr & ~0xFF);
142 int err;
143
144 err = regmap_raw_write(regmap, REG_PG255_BASE_HI, &addr_base,
145 sizeof(addr_base));
146 if (err)
147 return err;
148 return regmap_raw_write(regmap, REG_PG255_OFFS(addr), data, len);
149 }
150
zl38_fw_send_xaddr(struct regmap * regmap,const void * data)151 static int zl38_fw_send_xaddr(struct regmap *regmap, const void *data)
152 {
153 /* execution address from ihex: 32-bit little endian.
154 * device register expects 32-bit big endian.
155 */
156 u32 addr = le32_to_cpup(data);
157 __be32 baddr = cpu_to_be32(addr);
158
159 return regmap_raw_write(regmap, REG_FWR_EXEC, &baddr, sizeof(baddr));
160 }
161
zl38_load_firmware(struct device * dev,struct regmap * regmap)162 static int zl38_load_firmware(struct device *dev, struct regmap *regmap)
163 {
164 const struct ihex_binrec *rec;
165 const struct firmware *fw;
166 u32 addr;
167 u16 len;
168 int err;
169
170 /* how to get this firmware:
171 * 1. request and download chip firmware from Microsemi
172 * (provided by Microsemi in srec format)
173 * 2. convert downloaded firmware from srec to ihex. Simple tool:
174 * https://gitlab.com/TheSven73/s3-to-irec
175 * 3. convert ihex to binary (.fw) using ihex2fw tool which is included
176 * with the Linux kernel sources
177 */
178 err = request_ihex_firmware(&fw, "zl38060.fw", dev);
179 if (err)
180 return err;
181 err = zl38_fw_enter_boot_mode(regmap);
182 if (err)
183 goto out;
184 rec = (const struct ihex_binrec *)fw->data;
185 while (rec) {
186 addr = be32_to_cpu(rec->addr);
187 len = be16_to_cpu(rec->len);
188 if (addr) {
189 /* regular data ihex record */
190 err = zl38_fw_send_data(regmap, addr, rec->data, len);
191 } else if (len == 4) {
192 /* execution address ihex record */
193 err = zl38_fw_send_xaddr(regmap, rec->data);
194 } else {
195 err = -EINVAL;
196 }
197 if (err)
198 goto out;
199 /* next ! */
200 rec = ihex_next_binrec(rec);
201 }
202 err = zl38_fw_go(regmap);
203
204 out:
205 release_firmware(fw);
206 return err;
207 }
208
209
zl38_software_reset(struct regmap * regmap)210 static int zl38_software_reset(struct regmap *regmap)
211 {
212 unsigned int val;
213 int err;
214
215 err = regmap_update_bits(regmap, REG_SEMA_FLAGS, SEMA_FLAGS_APP_REBOOT,
216 SEMA_FLAGS_APP_REBOOT);
217 if (err)
218 return err;
219
220 /* wait for host bus interface to settle.
221 * Not sure if this is required: Microsemi's vendor driver does this,
222 * but the firmware manual does not mention it. Leave it in, there's
223 * little downside, apart from a slower reset.
224 */
225 msleep(50);
226
227 return regmap_read_poll_timeout(regmap, REG_SEMA_FLAGS, val,
228 !(val & SEMA_FLAGS_APP_REBOOT), 10000,
229 10000 * 100);
230 }
231
zl38_set_fmt(struct snd_soc_dai * dai,unsigned int fmt)232 static int zl38_set_fmt(struct snd_soc_dai *dai, unsigned int fmt)
233 {
234 struct zl38_codec_priv *priv = snd_soc_dai_get_drvdata(dai);
235 int err;
236
237 switch (fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
238 case SND_SOC_DAIFMT_I2S:
239 /* firmware default is normal i2s */
240 break;
241 default:
242 return -EINVAL;
243 }
244
245 switch (fmt & SND_SOC_DAIFMT_INV_MASK) {
246 case SND_SOC_DAIFMT_NB_NF:
247 /* firmware default is normal bitclock and frame */
248 break;
249 default:
250 return -EINVAL;
251 }
252
253 switch (fmt & SND_SOC_DAIFMT_CLOCK_PROVIDER_MASK) {
254 case SND_SOC_DAIFMT_CBP_CFP:
255 /* always 32 bits per frame (= 16 bits/channel, 2 channels) */
256 err = regmap_update_bits(priv->regmap, REG_TDMA_CFG_CLK,
257 CFG_CLK_MASTER | CFG_CLK_PCLK_MASK,
258 CFG_CLK_MASTER | CFG_CLK_PCLK(32));
259 if (err)
260 return err;
261 break;
262 default:
263 return -EINVAL;
264 }
265
266 return 0;
267 }
268
zl38_hw_params(struct snd_pcm_substream * substream,struct snd_pcm_hw_params * params,struct snd_soc_dai * dai)269 static int zl38_hw_params(struct snd_pcm_substream *substream,
270 struct snd_pcm_hw_params *params,
271 struct snd_soc_dai *dai)
272 {
273 struct zl38_codec_priv *priv = snd_soc_dai_get_drvdata(dai);
274 bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
275 unsigned int fsrate;
276 int err;
277
278 /* We cannot change hw_params while the dai is already in use - the
279 * software reset will corrupt the audio. However, this is not required,
280 * as the chip's TDM buses are fully symmetric, which mandates identical
281 * rates, channels, and samplebits for record and playback.
282 */
283 if (priv->is_stream_in_use[!tx])
284 goto skip_setup;
285
286 switch (params_rate(params)) {
287 case 8000:
288 fsrate = CFG_CLK_FSRATE_8KHZ;
289 break;
290 case 16000:
291 fsrate = CFG_CLK_FSRATE_16KHZ;
292 break;
293 case 48000:
294 fsrate = CFG_CLK_FSRATE_48KHZ;
295 break;
296 default:
297 return -EINVAL;
298 }
299
300 err = regmap_update_bits(priv->regmap, REG_TDMA_CFG_CLK,
301 CFG_CLK_FSRATE_MASK, fsrate);
302 if (err)
303 return err;
304
305 /* chip requires a software reset to apply audio register changes */
306 err = zl38_software_reset(priv->regmap);
307 if (err)
308 return err;
309
310 skip_setup:
311 priv->is_stream_in_use[tx] = true;
312
313 return 0;
314 }
315
zl38_hw_free(struct snd_pcm_substream * substream,struct snd_soc_dai * dai)316 static int zl38_hw_free(struct snd_pcm_substream *substream,
317 struct snd_soc_dai *dai)
318 {
319 struct zl38_codec_priv *priv = snd_soc_dai_get_drvdata(dai);
320 bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
321
322 priv->is_stream_in_use[tx] = false;
323
324 return 0;
325 }
326
327 /* stereo bypass with no AEC */
328 static const struct reg_sequence cp_config_stereo_bypass[] = {
329 /* interconnects must be programmed first */
330 { 0x0210, 0x0005 }, /* DAC1 in <= I2S1-L */
331 { 0x0212, 0x0006 }, /* DAC2 in <= I2S1-R */
332 { 0x0214, 0x0001 }, /* I2S1-L in <= MIC1 */
333 { 0x0216, 0x0001 }, /* I2S1-R in <= MIC1 */
334 { 0x0224, 0x0000 }, /* AEC-S in <= n/a */
335 { 0x0226, 0x0000 }, /* AEC-R in <= n/a */
336 /* output enables must be programmed next */
337 { 0x0202, 0x000F }, /* enable I2S1 + DAC */
338 };
339
340 static const struct snd_soc_dai_ops zl38_dai_ops = {
341 .set_fmt = zl38_set_fmt,
342 .hw_params = zl38_hw_params,
343 .hw_free = zl38_hw_free,
344 };
345
346 static struct snd_soc_dai_driver zl38_dai = {
347 .name = "zl38060-tdma",
348 .playback = {
349 .stream_name = "Playback",
350 .channels_min = 2,
351 .channels_max = 2,
352 .rates = ZL38_RATES,
353 .formats = ZL38_FORMATS,
354 },
355 .capture = {
356 .stream_name = "Capture",
357 .channels_min = 2,
358 .channels_max = 2,
359 .rates = ZL38_RATES,
360 .formats = ZL38_FORMATS,
361 },
362 .ops = &zl38_dai_ops,
363 .symmetric_rate = 1,
364 .symmetric_sample_bits = 1,
365 .symmetric_channels = 1,
366 };
367
368 static const struct snd_soc_dapm_widget zl38_dapm_widgets[] = {
369 SND_SOC_DAPM_OUTPUT("DAC1"),
370 SND_SOC_DAPM_OUTPUT("DAC2"),
371
372 SND_SOC_DAPM_INPUT("DMICL"),
373 };
374
375 static const struct snd_soc_dapm_route zl38_dapm_routes[] = {
376 { "DAC1", NULL, "Playback" },
377 { "DAC2", NULL, "Playback" },
378
379 { "Capture", NULL, "DMICL" },
380 };
381
382 static const struct snd_soc_component_driver zl38_component_dev = {
383 .dapm_widgets = zl38_dapm_widgets,
384 .num_dapm_widgets = ARRAY_SIZE(zl38_dapm_widgets),
385 .dapm_routes = zl38_dapm_routes,
386 .num_dapm_routes = ARRAY_SIZE(zl38_dapm_routes),
387 .endianness = 1,
388 };
389
chip_gpio_set(struct gpio_chip * c,unsigned int offset,int val)390 static void chip_gpio_set(struct gpio_chip *c, unsigned int offset, int val)
391 {
392 struct regmap *regmap = gpiochip_get_data(c);
393 unsigned int mask = BIT(offset);
394
395 regmap_update_bits(regmap, REG_GPIO_DAT, mask, val ? mask : 0);
396 }
397
chip_gpio_get(struct gpio_chip * c,unsigned int offset)398 static int chip_gpio_get(struct gpio_chip *c, unsigned int offset)
399 {
400 struct regmap *regmap = gpiochip_get_data(c);
401 unsigned int mask = BIT(offset);
402 unsigned int val;
403 int err;
404
405 err = regmap_read(regmap, REG_GPIO_DAT, &val);
406 if (err)
407 return err;
408
409 return !!(val & mask);
410 }
411
chip_direction_input(struct gpio_chip * c,unsigned int offset)412 static int chip_direction_input(struct gpio_chip *c, unsigned int offset)
413 {
414 struct regmap *regmap = gpiochip_get_data(c);
415 unsigned int mask = BIT(offset);
416
417 return regmap_update_bits(regmap, REG_GPIO_DIR, mask, 0);
418 }
419
420 static int
chip_direction_output(struct gpio_chip * c,unsigned int offset,int val)421 chip_direction_output(struct gpio_chip *c, unsigned int offset, int val)
422 {
423 struct regmap *regmap = gpiochip_get_data(c);
424 unsigned int mask = BIT(offset);
425
426 chip_gpio_set(c, offset, val);
427 return regmap_update_bits(regmap, REG_GPIO_DIR, mask, mask);
428 }
429
430 static const struct gpio_chip template_chip = {
431 .owner = THIS_MODULE,
432 .label = DRV_NAME,
433
434 .base = -1,
435 .ngpio = 14,
436 .direction_input = chip_direction_input,
437 .direction_output = chip_direction_output,
438 .get = chip_gpio_get,
439 .set = chip_gpio_set,
440
441 .can_sleep = true,
442 };
443
zl38_check_revision(struct device * dev,struct regmap * regmap)444 static int zl38_check_revision(struct device *dev, struct regmap *regmap)
445 {
446 unsigned int hwrev, fwprod, fwrev;
447 int fw_major, fw_minor, fw_micro;
448 int err;
449
450 err = regmap_read(regmap, REG_HW_REV, &hwrev);
451 if (err)
452 return err;
453 err = regmap_read(regmap, REG_FW_PROD, &fwprod);
454 if (err)
455 return err;
456 err = regmap_read(regmap, REG_FW_REV, &fwrev);
457 if (err)
458 return err;
459
460 fw_major = (fwrev >> 12) & 0xF;
461 fw_minor = (fwrev >> 8) & 0xF;
462 fw_micro = fwrev & 0xFF;
463 dev_info(dev, "hw rev 0x%x, fw product code %d, firmware rev %d.%d.%d",
464 hwrev & 0x1F, fwprod, fw_major, fw_minor, fw_micro);
465
466 if (fw_major != FIRMWARE_MAJOR || fw_minor < FIRMWARE_MINOR) {
467 dev_err(dev, "unsupported firmware. driver supports %d.%d",
468 FIRMWARE_MAJOR, FIRMWARE_MINOR);
469 return -EINVAL;
470 }
471
472 return 0;
473 }
474
zl38_bus_read(void * context,const void * reg_buf,size_t reg_size,void * val_buf,size_t val_size)475 static int zl38_bus_read(void *context,
476 const void *reg_buf, size_t reg_size,
477 void *val_buf, size_t val_size)
478 {
479 struct spi_device *spi = context;
480 const u8 *reg_buf8 = reg_buf;
481 size_t len = 0;
482 u8 offs, page;
483 u8 txbuf[4];
484
485 if (reg_size != 2 || val_size > ZL38_MAX_RAW_XFER)
486 return -EINVAL;
487
488 offs = reg_buf8[1] >> 1;
489 page = reg_buf8[0];
490
491 if (page) {
492 txbuf[len++] = 0xFE;
493 txbuf[len++] = page == HBI_FIRMWARE_PAGE ? 0xFF : page - 1;
494 txbuf[len++] = offs;
495 txbuf[len++] = val_size / 2 - 1;
496 } else {
497 txbuf[len++] = offs | 0x80;
498 txbuf[len++] = val_size / 2 - 1;
499 }
500
501 return spi_write_then_read(spi, txbuf, len, val_buf, val_size);
502 }
503
zl38_bus_write(void * context,const void * data,size_t count)504 static int zl38_bus_write(void *context, const void *data, size_t count)
505 {
506 struct spi_device *spi = context;
507 u8 buf[4 + ZL38_MAX_RAW_XFER];
508 size_t val_len, len = 0;
509 const u8 *data8 = data;
510 u8 offs, page;
511
512 if (count > (2 + ZL38_MAX_RAW_XFER) || count < 4)
513 return -EINVAL;
514 val_len = count - 2;
515 offs = data8[1] >> 1;
516 page = data8[0];
517
518 if (page) {
519 buf[len++] = 0xFE;
520 buf[len++] = page == HBI_FIRMWARE_PAGE ? 0xFF : page - 1;
521 buf[len++] = offs;
522 buf[len++] = (val_len / 2 - 1) | 0x80;
523 } else {
524 buf[len++] = offs | 0x80;
525 buf[len++] = (val_len / 2 - 1) | 0x80;
526 }
527 memcpy(buf + len, data8 + 2, val_len);
528 len += val_len;
529
530 return spi_write(spi, buf, len);
531 }
532
533 static const struct regmap_bus zl38_regmap_bus = {
534 .read = zl38_bus_read,
535 .write = zl38_bus_write,
536 .max_raw_write = ZL38_MAX_RAW_XFER,
537 .max_raw_read = ZL38_MAX_RAW_XFER,
538 };
539
540 static const struct regmap_config zl38_regmap_conf = {
541 .reg_bits = 16,
542 .val_bits = 16,
543 .reg_stride = 2,
544 .use_single_read = true,
545 .use_single_write = true,
546 };
547
zl38_spi_probe(struct spi_device * spi)548 static int zl38_spi_probe(struct spi_device *spi)
549 {
550 struct device *dev = &spi->dev;
551 struct zl38_codec_priv *priv;
552 struct gpio_desc *reset_gpio;
553 int err;
554
555 /* get the chip to a known state by putting it in reset */
556 reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
557 if (IS_ERR(reset_gpio))
558 return PTR_ERR(reset_gpio);
559 if (reset_gpio) {
560 /* datasheet: need > 10us for a digital + analog reset */
561 usleep_range(15, 50);
562 /* take the chip out of reset */
563 gpiod_set_value_cansleep(reset_gpio, 0);
564 /* datasheet: need > 3ms for digital section to become stable */
565 usleep_range(3000, 10000);
566 }
567
568 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
569 if (!priv)
570 return -ENOMEM;
571
572 priv->dev = dev;
573 dev_set_drvdata(dev, priv);
574 priv->regmap = devm_regmap_init(dev, &zl38_regmap_bus, spi,
575 &zl38_regmap_conf);
576 if (IS_ERR(priv->regmap))
577 return PTR_ERR(priv->regmap);
578
579 err = zl38_load_firmware(dev, priv->regmap);
580 if (err)
581 return err;
582
583 err = zl38_check_revision(dev, priv->regmap);
584 if (err)
585 return err;
586
587 priv->gpio_chip = devm_kmemdup(dev, &template_chip,
588 sizeof(template_chip), GFP_KERNEL);
589 if (!priv->gpio_chip)
590 return -ENOMEM;
591 priv->gpio_chip->parent = dev;
592 err = devm_gpiochip_add_data(dev, priv->gpio_chip, priv->regmap);
593 if (err)
594 return err;
595
596 /* setup the cross-point switch for stereo bypass */
597 err = regmap_multi_reg_write(priv->regmap, cp_config_stereo_bypass,
598 ARRAY_SIZE(cp_config_stereo_bypass));
599 if (err)
600 return err;
601 /* setup for 12MHz crystal connected to the chip */
602 err = regmap_update_bits(priv->regmap, REG_CLK_CFG, CLK_CFG_SOURCE_XTAL,
603 CLK_CFG_SOURCE_XTAL);
604 if (err)
605 return err;
606
607 return devm_snd_soc_register_component(dev, &zl38_component_dev,
608 &zl38_dai, 1);
609 }
610
611 static const struct of_device_id zl38_dt_ids[] __maybe_unused = {
612 { .compatible = "mscc,zl38060", },
613 { /* sentinel */ }
614 };
615 MODULE_DEVICE_TABLE(of, zl38_dt_ids);
616
617 static const struct spi_device_id zl38_spi_ids[] = {
618 { "zl38060", 0 },
619 { /* sentinel */ }
620 };
621 MODULE_DEVICE_TABLE(spi, zl38_spi_ids);
622
623 static struct spi_driver zl38060_spi_driver = {
624 .driver = {
625 .name = DRV_NAME,
626 .of_match_table = of_match_ptr(zl38_dt_ids),
627 },
628 .probe = zl38_spi_probe,
629 .id_table = zl38_spi_ids,
630 };
631 module_spi_driver(zl38060_spi_driver);
632
633 MODULE_DESCRIPTION("ASoC ZL38060 driver");
634 MODULE_AUTHOR("Sven Van Asbroeck <TheSven73@gmail.com>");
635 MODULE_LICENSE("GPL v2");
636