1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2015 VanguardiaSur - www.vanguardiasur.com.ar
4  *
5  * Based on original driver by Krzysztof Ha?asa:
6  * Copyright (C) 2015 Industrial Research Institute for Automation
7  * and Measurements PIAP
8  *
9  * Notes
10  * -----
11  *
12  * 1. Under stress-testing, it has been observed that the PCIe link
13  * goes down, without reason. Therefore, the driver takes special care
14  * to allow device hot-unplugging.
15  *
16  * 2. TW686X devices are capable of setting a few different DMA modes,
17  * including: scatter-gather, field and frame modes. However,
18  * under stress testings it has been found that the machine can
19  * freeze completely if DMA registers are programmed while streaming
20  * is active.
21  *
22  * Therefore, driver implements a dma_mode called 'memcpy' which
23  * avoids cycling the DMA buffers, and insteads allocates extra DMA buffers
24  * and then copies into vmalloc'ed user buffers.
25  *
26  * In addition to this, when streaming is on, the driver tries to access
27  * hardware registers as infrequently as possible. This is done by using
28  * a timer to limit the rate at which DMA is reset on DMA channels error.
29  */
30 
31 #include <linux/init.h>
32 #include <linux/interrupt.h>
33 #include <linux/delay.h>
34 #include <linux/kernel.h>
35 #include <linux/module.h>
36 #include <linux/pci_ids.h>
37 #include <linux/slab.h>
38 #include <linux/timer.h>
39 
40 #include "tw686x.h"
41 #include "tw686x-regs.h"
42 
43 /*
44  * This module parameter allows to control the DMA_TIMER_INTERVAL value.
45  * The DMA_TIMER_INTERVAL register controls the minimum DMA interrupt
46  * time span (iow, the maximum DMA interrupt rate) thus allowing for
47  * IRQ coalescing.
48  *
49  * The chip datasheet does not mention a time unit for this value, so
50  * users wanting fine-grain control over the interrupt rate should
51  * determine the desired value through testing.
52  */
53 static u32 dma_interval = 0x00098968;
54 module_param(dma_interval, int, 0444);
55 MODULE_PARM_DESC(dma_interval, "Minimum time span for DMA interrupting host");
56 
57 static unsigned int dma_mode = TW686X_DMA_MODE_MEMCPY;
58 static const char *dma_mode_name(unsigned int mode)
59 {
60 	switch (mode) {
61 	case TW686X_DMA_MODE_MEMCPY:
62 		return "memcpy";
63 	case TW686X_DMA_MODE_CONTIG:
64 		return "contig";
65 	case TW686X_DMA_MODE_SG:
66 		return "sg";
67 	default:
68 		return "unknown";
69 	}
70 }
71 
72 static int tw686x_dma_mode_get(char *buffer, const struct kernel_param *kp)
73 {
74 	return sprintf(buffer, "%s", dma_mode_name(dma_mode));
75 }
76 
77 static int tw686x_dma_mode_set(const char *val, const struct kernel_param *kp)
78 {
79 	if (!strcasecmp(val, dma_mode_name(TW686X_DMA_MODE_MEMCPY)))
80 		dma_mode = TW686X_DMA_MODE_MEMCPY;
81 	else if (!strcasecmp(val, dma_mode_name(TW686X_DMA_MODE_CONTIG)))
82 		dma_mode = TW686X_DMA_MODE_CONTIG;
83 	else if (!strcasecmp(val, dma_mode_name(TW686X_DMA_MODE_SG)))
84 		dma_mode = TW686X_DMA_MODE_SG;
85 	else
86 		return -EINVAL;
87 	return 0;
88 }
89 module_param_call(dma_mode, tw686x_dma_mode_set, tw686x_dma_mode_get,
90 		  &dma_mode, S_IRUGO|S_IWUSR);
91 MODULE_PARM_DESC(dma_mode, "DMA operation mode (memcpy/contig/sg, default=memcpy)");
92 
93 void tw686x_disable_channel(struct tw686x_dev *dev, unsigned int channel)
94 {
95 	u32 dma_en = reg_read(dev, DMA_CHANNEL_ENABLE);
96 	u32 dma_cmd = reg_read(dev, DMA_CMD);
97 
98 	dma_en &= ~BIT(channel);
99 	dma_cmd &= ~BIT(channel);
100 
101 	/* Must remove it from pending too */
102 	dev->pending_dma_en &= ~BIT(channel);
103 	dev->pending_dma_cmd &= ~BIT(channel);
104 
105 	/* Stop DMA if no channels are enabled */
106 	if (!dma_en)
107 		dma_cmd = 0;
108 	reg_write(dev, DMA_CHANNEL_ENABLE, dma_en);
109 	reg_write(dev, DMA_CMD, dma_cmd);
110 }
111 
112 void tw686x_enable_channel(struct tw686x_dev *dev, unsigned int channel)
113 {
114 	u32 dma_en = reg_read(dev, DMA_CHANNEL_ENABLE);
115 	u32 dma_cmd = reg_read(dev, DMA_CMD);
116 
117 	dev->pending_dma_en |= dma_en | BIT(channel);
118 	dev->pending_dma_cmd |= dma_cmd | DMA_CMD_ENABLE | BIT(channel);
119 }
120 
121 /*
122  * The purpose of this awful hack is to avoid enabling the DMA
123  * channels "too fast" which makes some TW686x devices very
124  * angry and freeze the CPU (see note 1).
125  */
126 static void tw686x_dma_delay(struct timer_list *t)
127 {
128 	struct tw686x_dev *dev = from_timer(dev, t, dma_delay_timer);
129 	unsigned long flags;
130 
131 	spin_lock_irqsave(&dev->lock, flags);
132 
133 	reg_write(dev, DMA_CHANNEL_ENABLE, dev->pending_dma_en);
134 	reg_write(dev, DMA_CMD, dev->pending_dma_cmd);
135 	dev->pending_dma_en = 0;
136 	dev->pending_dma_cmd = 0;
137 
138 	spin_unlock_irqrestore(&dev->lock, flags);
139 }
140 
141 static void tw686x_reset_channels(struct tw686x_dev *dev, unsigned int ch_mask)
142 {
143 	u32 dma_en, dma_cmd;
144 
145 	dma_en = reg_read(dev, DMA_CHANNEL_ENABLE);
146 	dma_cmd = reg_read(dev, DMA_CMD);
147 
148 	/*
149 	 * Save pending register status, the timer will
150 	 * restore them.
151 	 */
152 	dev->pending_dma_en |= dma_en;
153 	dev->pending_dma_cmd |= dma_cmd;
154 
155 	/* Disable the reset channels */
156 	reg_write(dev, DMA_CHANNEL_ENABLE, dma_en & ~ch_mask);
157 
158 	if ((dma_en & ~ch_mask) == 0) {
159 		dev_dbg(&dev->pci_dev->dev, "reset: stopping DMA\n");
160 		dma_cmd &= ~DMA_CMD_ENABLE;
161 	}
162 	reg_write(dev, DMA_CMD, dma_cmd & ~ch_mask);
163 }
164 
165 static irqreturn_t tw686x_irq(int irq, void *dev_id)
166 {
167 	struct tw686x_dev *dev = (struct tw686x_dev *)dev_id;
168 	unsigned int video_requests, audio_requests, reset_ch;
169 	u32 fifo_status, fifo_signal, fifo_ov, fifo_bad, fifo_errors;
170 	u32 int_status, dma_en, video_en, pb_status;
171 	unsigned long flags;
172 
173 	int_status = reg_read(dev, INT_STATUS); /* cleared on read */
174 	fifo_status = reg_read(dev, VIDEO_FIFO_STATUS);
175 
176 	/* INT_STATUS does not include FIFO_STATUS errors! */
177 	if (!int_status && !TW686X_FIFO_ERROR(fifo_status))
178 		return IRQ_NONE;
179 
180 	if (int_status & INT_STATUS_DMA_TOUT) {
181 		dev_dbg(&dev->pci_dev->dev,
182 			"DMA timeout. Resetting DMA for all channels\n");
183 		reset_ch = ~0;
184 		goto reset_channels;
185 	}
186 
187 	spin_lock_irqsave(&dev->lock, flags);
188 	dma_en = reg_read(dev, DMA_CHANNEL_ENABLE);
189 	spin_unlock_irqrestore(&dev->lock, flags);
190 
191 	video_en = dma_en & 0xff;
192 	fifo_signal = ~(fifo_status & 0xff) & video_en;
193 	fifo_ov = fifo_status >> 24;
194 	fifo_bad = fifo_status >> 16;
195 
196 	/* Mask of channels with signal and FIFO errors */
197 	fifo_errors = fifo_signal & (fifo_ov | fifo_bad);
198 
199 	reset_ch = 0;
200 	pb_status = reg_read(dev, PB_STATUS);
201 
202 	/* Coalesce video frame/error events */
203 	video_requests = (int_status & video_en) | fifo_errors;
204 	audio_requests = (int_status & dma_en) >> 8;
205 
206 	if (video_requests)
207 		tw686x_video_irq(dev, video_requests, pb_status,
208 				 fifo_status, &reset_ch);
209 	if (audio_requests)
210 		tw686x_audio_irq(dev, audio_requests, pb_status);
211 
212 reset_channels:
213 	if (reset_ch) {
214 		spin_lock_irqsave(&dev->lock, flags);
215 		tw686x_reset_channels(dev, reset_ch);
216 		spin_unlock_irqrestore(&dev->lock, flags);
217 		mod_timer(&dev->dma_delay_timer,
218 			  jiffies + msecs_to_jiffies(100));
219 	}
220 
221 	return IRQ_HANDLED;
222 }
223 
224 static void tw686x_dev_release(struct v4l2_device *v4l2_dev)
225 {
226 	struct tw686x_dev *dev = container_of(v4l2_dev, struct tw686x_dev,
227 					      v4l2_dev);
228 	unsigned int ch;
229 
230 	for (ch = 0; ch < max_channels(dev); ch++)
231 		v4l2_ctrl_handler_free(&dev->video_channels[ch].ctrl_handler);
232 
233 	v4l2_device_unregister(&dev->v4l2_dev);
234 
235 	kfree(dev->audio_channels);
236 	kfree(dev->video_channels);
237 	kfree(dev);
238 }
239 
240 static int tw686x_probe(struct pci_dev *pci_dev,
241 			const struct pci_device_id *pci_id)
242 {
243 	struct tw686x_dev *dev;
244 	int err;
245 
246 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
247 	if (!dev)
248 		return -ENOMEM;
249 	dev->type = pci_id->driver_data;
250 	dev->dma_mode = dma_mode;
251 	sprintf(dev->name, "tw%04X", pci_dev->device);
252 
253 	dev->video_channels = kcalloc(max_channels(dev),
254 		sizeof(*dev->video_channels), GFP_KERNEL);
255 	if (!dev->video_channels) {
256 		err = -ENOMEM;
257 		goto free_dev;
258 	}
259 
260 	dev->audio_channels = kcalloc(max_channels(dev),
261 		sizeof(*dev->audio_channels), GFP_KERNEL);
262 	if (!dev->audio_channels) {
263 		err = -ENOMEM;
264 		goto free_video;
265 	}
266 
267 	pr_info("%s: PCI %s, IRQ %d, MMIO 0x%lx (%s mode)\n", dev->name,
268 		pci_name(pci_dev), pci_dev->irq,
269 		(unsigned long)pci_resource_start(pci_dev, 0),
270 		dma_mode_name(dma_mode));
271 
272 	dev->pci_dev = pci_dev;
273 	if (pci_enable_device(pci_dev)) {
274 		err = -EIO;
275 		goto free_audio;
276 	}
277 
278 	pci_set_master(pci_dev);
279 	err = dma_set_mask(&pci_dev->dev, DMA_BIT_MASK(32));
280 	if (err) {
281 		dev_err(&pci_dev->dev, "32-bit PCI DMA not supported\n");
282 		err = -EIO;
283 		goto disable_pci;
284 	}
285 
286 	err = pci_request_regions(pci_dev, dev->name);
287 	if (err) {
288 		dev_err(&pci_dev->dev, "unable to request PCI region\n");
289 		goto disable_pci;
290 	}
291 
292 	dev->mmio = pci_ioremap_bar(pci_dev, 0);
293 	if (!dev->mmio) {
294 		dev_err(&pci_dev->dev, "unable to remap PCI region\n");
295 		err = -ENOMEM;
296 		goto free_region;
297 	}
298 
299 	/* Reset all subsystems */
300 	reg_write(dev, SYS_SOFT_RST, 0x0f);
301 	mdelay(1);
302 
303 	reg_write(dev, SRST[0], 0x3f);
304 	if (max_channels(dev) > 4)
305 		reg_write(dev, SRST[1], 0x3f);
306 
307 	/* Disable the DMA engine */
308 	reg_write(dev, DMA_CMD, 0);
309 	reg_write(dev, DMA_CHANNEL_ENABLE, 0);
310 
311 	/* Enable DMA FIFO overflow and pointer check */
312 	reg_write(dev, DMA_CONFIG, 0xffffff04);
313 	reg_write(dev, DMA_CHANNEL_TIMEOUT, 0x140c8584);
314 	reg_write(dev, DMA_TIMER_INTERVAL, dma_interval);
315 
316 	spin_lock_init(&dev->lock);
317 
318 	err = request_irq(pci_dev->irq, tw686x_irq, IRQF_SHARED,
319 			  dev->name, dev);
320 	if (err < 0) {
321 		dev_err(&pci_dev->dev, "unable to request interrupt\n");
322 		goto iounmap;
323 	}
324 
325 	timer_setup(&dev->dma_delay_timer, tw686x_dma_delay, 0);
326 
327 	/*
328 	 * This must be set right before initializing v4l2_dev.
329 	 * It's used to release resources after the last handle
330 	 * held is released.
331 	 */
332 	dev->v4l2_dev.release = tw686x_dev_release;
333 	err = tw686x_video_init(dev);
334 	if (err) {
335 		dev_err(&pci_dev->dev, "can't register video\n");
336 		goto free_irq;
337 	}
338 
339 	err = tw686x_audio_init(dev);
340 	if (err)
341 		dev_warn(&pci_dev->dev, "can't register audio\n");
342 
343 	pci_set_drvdata(pci_dev, dev);
344 	return 0;
345 
346 free_irq:
347 	free_irq(pci_dev->irq, dev);
348 iounmap:
349 	pci_iounmap(pci_dev, dev->mmio);
350 free_region:
351 	pci_release_regions(pci_dev);
352 disable_pci:
353 	pci_disable_device(pci_dev);
354 free_audio:
355 	kfree(dev->audio_channels);
356 free_video:
357 	kfree(dev->video_channels);
358 free_dev:
359 	kfree(dev);
360 	return err;
361 }
362 
363 static void tw686x_remove(struct pci_dev *pci_dev)
364 {
365 	struct tw686x_dev *dev = pci_get_drvdata(pci_dev);
366 	unsigned long flags;
367 
368 	/* This guarantees the IRQ handler is no longer running,
369 	 * which means we can kiss good-bye some resources.
370 	 */
371 	free_irq(pci_dev->irq, dev);
372 
373 	tw686x_video_free(dev);
374 	tw686x_audio_free(dev);
375 	del_timer_sync(&dev->dma_delay_timer);
376 
377 	pci_iounmap(pci_dev, dev->mmio);
378 	pci_release_regions(pci_dev);
379 	pci_disable_device(pci_dev);
380 
381 	/*
382 	 * Setting pci_dev to NULL allows to detect hardware is no longer
383 	 * available and will be used by vb2_ops. This is required because
384 	 * the device sometimes hot-unplugs itself as the result of a PCIe
385 	 * link down.
386 	 * The lock is really important here.
387 	 */
388 	spin_lock_irqsave(&dev->lock, flags);
389 	dev->pci_dev = NULL;
390 	spin_unlock_irqrestore(&dev->lock, flags);
391 
392 	/*
393 	 * This calls tw686x_dev_release if it's the last reference.
394 	 * Otherwise, release is postponed until there are no users left.
395 	 */
396 	v4l2_device_put(&dev->v4l2_dev);
397 }
398 
399 /*
400  * On TW6864 and TW6868, all channels share the pair of video DMA SG tables,
401  * with 10-bit start_idx and end_idx determining start and end of frame buffer
402  * for particular channel.
403  * TW6868 with all its 8 channels would be problematic (only 127 SG entries per
404  * channel) but we support only 4 channels on this chip anyway (the first
405  * 4 channels are driven with internal video decoder, the other 4 would require
406  * an external TW286x part).
407  *
408  * On TW6865 and TW6869, each channel has its own DMA SG table, with indexes
409  * starting with 0. Both chips have complete sets of internal video decoders
410  * (respectively 4 or 8-channel).
411  *
412  * All chips have separate SG tables for two video frames.
413  */
414 
415 /* driver_data is number of A/V channels */
416 static const struct pci_device_id tw686x_pci_tbl[] = {
417 	{
418 		PCI_DEVICE(PCI_VENDOR_ID_TECHWELL, 0x6864),
419 		.driver_data = 4
420 	},
421 	{
422 		PCI_DEVICE(PCI_VENDOR_ID_TECHWELL, 0x6865), /* not tested */
423 		.driver_data = 4 | TYPE_SECOND_GEN
424 	},
425 	/*
426 	 * TW6868 supports 8 A/V channels with an external TW2865 chip;
427 	 * not supported by the driver.
428 	 */
429 	{
430 		PCI_DEVICE(PCI_VENDOR_ID_TECHWELL, 0x6868), /* not tested */
431 		.driver_data = 4
432 	},
433 	{
434 		PCI_DEVICE(PCI_VENDOR_ID_TECHWELL, 0x6869),
435 		.driver_data = 8 | TYPE_SECOND_GEN},
436 	{}
437 };
438 MODULE_DEVICE_TABLE(pci, tw686x_pci_tbl);
439 
440 static struct pci_driver tw686x_pci_driver = {
441 	.name = "tw686x",
442 	.id_table = tw686x_pci_tbl,
443 	.probe = tw686x_probe,
444 	.remove = tw686x_remove,
445 };
446 module_pci_driver(tw686x_pci_driver);
447 
448 MODULE_DESCRIPTION("Driver for video frame grabber cards based on Intersil/Techwell TW686[4589]");
449 MODULE_AUTHOR("Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>");
450 MODULE_AUTHOR("Krzysztof Ha?asa <khalasa@piap.pl>");
451 MODULE_LICENSE("GPL v2");
452