text: /*
   * Driver for the Atmel on-chip Audio Bitstream DAC (ABDAC)
   *
   * Copyright (C) 2006-2009 Atmel Corporation
   *
   * 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/clk.h>
  #include <linux/bitmap.h>
  #include <linux/dw_dmac.h>
  #include <linux/dmaengine.h>
  #include <linux/dma-mapping.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>
  #include <linux/module.h>
  #include <linux/platform_device.h>
  #include <linux/types.h>
  #include <linux/io.h>
  
  #include <sound/core.h>
  #include <sound/initval.h>
  #include <sound/pcm.h>
  #include <sound/pcm_params.h>
  #include <sound/atmel-abdac.h>
  
  /* DAC register offsets */
  #define DAC_DATA                                0x0000
  #define DAC_CTRL                                0x0008
  #define DAC_INT_MASK                            0x000c
  #define DAC_INT_EN                              0x0010
  #define DAC_INT_DIS                             0x0014
  #define DAC_INT_CLR                             0x0018
  #define DAC_INT_STATUS                          0x001c
  
  /* Bitfields in CTRL */
  #define DAC_SWAP_OFFSET                         30
  #define DAC_SWAP_SIZE                           1
  #define DAC_EN_OFFSET                           31
  #define DAC_EN_SIZE                             1
  
  /* Bitfields in INT_MASK/INT_EN/INT_DIS/INT_STATUS/INT_CLR */
  #define DAC_UNDERRUN_OFFSET                     28
  #define DAC_UNDERRUN_SIZE                       1
  #define DAC_TX_READY_OFFSET                     29
  #define DAC_TX_READY_SIZE                       1
  
  /* Bit manipulation macros */
  #define DAC_BIT(name)					\
  	(1 << DAC_##name##_OFFSET)
  #define DAC_BF(name, value)				\
  	(((value) & ((1 << DAC_##name##_SIZE) - 1))	\
  	 << DAC_##name##_OFFSET)
  #define DAC_BFEXT(name, value)				\
  	(((value) >> DAC_##name##_OFFSET)		\
  	 & ((1 << DAC_##name##_SIZE) - 1))
  #define DAC_BFINS(name, value, old)			\
  	(((old) & ~(((1 << DAC_##name##_SIZE) - 1)	\
  		    << DAC_##name##_OFFSET))		\
  	 | DAC_BF(name, value))
  
  /* Register access macros */
  #define dac_readl(port, reg)				\
  	__raw_readl((port)->regs + DAC_##reg)
  #define dac_writel(port, reg, value)			\
  	__raw_writel((value), (port)->regs + DAC_##reg)
  
  /*
   * ABDAC supports a maximum of 6 different rates from a generic clock. The
   * generic clock has a power of two divider, which gives 6 steps from 192 kHz
   * to 5112 Hz.
   */
  #define MAX_NUM_RATES	6
  /* ALSA seems to use rates between 192000 Hz and 5112 Hz. */
  #define RATE_MAX	192000
  #define RATE_MIN	5112
  
  enum {
  	DMA_READY = 0,
  };
  
  struct atmel_abdac_dma {
  	struct dma_chan		*chan;
  	struct dw_cyclic_desc	*cdesc;
  };
  
  struct atmel_abdac {
  	struct clk				*pclk;
  	struct clk				*sample_clk;
  	struct platform_device			*pdev;
  	struct atmel_abdac_dma			dma;
  
  	struct snd_pcm_hw_constraint_list	constraints_rates;
  	struct snd_pcm_substream		*substream;
  	struct snd_card				*card;
  	struct snd_pcm				*pcm;
  
  	void __iomem				*regs;
  	unsigned long				flags;
  	unsigned int				rates[MAX_NUM_RATES];
  	unsigned int				rates_num;
  	int					irq;
  };
  
  #define get_dac(card) ((struct atmel_abdac *)(card)->private_data)
  
  /* This function is called by the DMA driver. */
  static void atmel_abdac_dma_period_done(void *arg)
  {
  	struct atmel_abdac *dac = arg;
  	snd_pcm_period_elapsed(dac->substream);
  }
  
  static int atmel_abdac_prepare_dma(struct atmel_abdac *dac,
  		struct snd_pcm_substream *substream,
  		enum dma_data_direction direction)
  {
  	struct dma_chan			*chan = dac->dma.chan;
  	struct dw_cyclic_desc		*cdesc;
  	struct snd_pcm_runtime		*runtime = substream->runtime;
  	unsigned long			buffer_len, period_len;
  
  	/*
  	 * We don't do DMA on "complex" transfers, i.e. with
  	 * non-halfword-aligned buffers or lengths.
  	 */
  	if (runtime->dma_addr & 1 || runtime->buffer_size & 1) {
  		dev_dbg(&dac->pdev->dev, "too complex transfer\n");
  		return -EINVAL;
  	}
  
  	buffer_len = frames_to_bytes(runtime, runtime->buffer_size);
  	period_len = frames_to_bytes(runtime, runtime->period_size);
  
  	cdesc = dw_dma_cyclic_prep(chan, runtime->dma_addr, buffer_len,
  			period_len, DMA_MEM_TO_DEV);
  	if (IS_ERR(cdesc)) {
  		dev_dbg(&dac->pdev->dev, "could not prepare cyclic DMA\n");
  		return PTR_ERR(cdesc);
  	}
  
  	cdesc->period_callback = atmel_abdac_dma_period_done;
  	cdesc->period_callback_param = dac;
  
  	dac->dma.cdesc = cdesc;
  
  	set_bit(DMA_READY, &dac->flags);
  
  	return 0;
  }
  
  static struct snd_pcm_hardware atmel_abdac_hw = {
  	.info			= (SNDRV_PCM_INFO_MMAP
  				  | SNDRV_PCM_INFO_MMAP_VALID
  				  | SNDRV_PCM_INFO_INTERLEAVED
  				  | SNDRV_PCM_INFO_BLOCK_TRANSFER
  				  | SNDRV_PCM_INFO_RESUME
  				  | SNDRV_PCM_INFO_PAUSE),
  	.formats		= (SNDRV_PCM_FMTBIT_S16_BE),
  	.rates			= (SNDRV_PCM_RATE_KNOT),
  	.rate_min		= RATE_MIN,
  	.rate_max		= RATE_MAX,
  	.channels_min		= 2,
  	.channels_max		= 2,
  	.buffer_bytes_max	= 64 * 4096,
  	.period_bytes_min	= 4096,
  	.period_bytes_max	= 4096,
  	.periods_min		= 6,
  	.periods_max		= 64,
  };
  
  static int atmel_abdac_open(struct snd_pcm_substream *substream)
  {
  	struct atmel_abdac *dac = snd_pcm_substream_chip(substream);
  
  	dac->substream = substream;
  	atmel_abdac_hw.rate_max = dac->rates[dac->rates_num - 1];
  	atmel_abdac_hw.rate_min = dac->rates[0];
  	substream->runtime->hw = atmel_abdac_hw;
  
  	return snd_pcm_hw_constraint_list(substream->runtime, 0,
  			SNDRV_PCM_HW_PARAM_RATE, &dac->constraints_rates);
  }
  
  static int atmel_abdac_close(struct snd_pcm_substream *substream)
  {
  	struct atmel_abdac *dac = snd_pcm_substream_chip(substream);
  	dac->substream = NULL;
  	return 0;
  }
  
  static int atmel_abdac_hw_params(struct snd_pcm_substream *substream,
  		struct snd_pcm_hw_params *hw_params)
  {
  	struct atmel_abdac *dac = snd_pcm_substream_chip(substream);
  	int retval;
  
  	retval = snd_pcm_lib_malloc_pages(substream,
  			params_buffer_bytes(hw_params));
  	if (retval < 0)
  		return retval;
  	/* snd_pcm_lib_malloc_pages returns 1 if buffer is changed. */
  	if (retval == 1)
  		if (test_and_clear_bit(DMA_READY, &dac->flags))
  			dw_dma_cyclic_free(dac->dma.chan);
  
  	return retval;
  }
  
  static int atmel_abdac_hw_free(struct snd_pcm_substream *substream)
  {
  	struct atmel_abdac *dac = snd_pcm_substream_chip(substream);
  	if (test_and_clear_bit(DMA_READY, &dac->flags))
  		dw_dma_cyclic_free(dac->dma.chan);
  	return snd_pcm_lib_free_pages(substream);
  }
  
  static int atmel_abdac_prepare(struct snd_pcm_substream *substream)
  {
  	struct atmel_abdac *dac = snd_pcm_substream_chip(substream);
  	int retval;
  
  	retval = clk_set_rate(dac->sample_clk, 256 * substream->runtime->rate);
  	if (retval)
  		return retval;
  
  	if (!test_bit(DMA_READY, &dac->flags))
  		retval = atmel_abdac_prepare_dma(dac, substream, DMA_TO_DEVICE);
  
  	return retval;
  }
  
  static int atmel_abdac_trigger(struct snd_pcm_substream *substream, int cmd)
  {
  	struct atmel_abdac *dac = snd_pcm_substream_chip(substream);
  	int retval = 0;
  
  	switch (cmd) {
  	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: /* fall through */
  	case SNDRV_PCM_TRIGGER_RESUME: /* fall through */
  	case SNDRV_PCM_TRIGGER_START:
  		clk_enable(dac->sample_clk);
  		retval = dw_dma_cyclic_start(dac->dma.chan);
  		if (retval)
  			goto out;
  		dac_writel(dac, CTRL, DAC_BIT(EN));
  		break;
  	case SNDRV_PCM_TRIGGER_PAUSE_PUSH: /* fall through */
  	case SNDRV_PCM_TRIGGER_SUSPEND: /* fall through */
  	case SNDRV_PCM_TRIGGER_STOP:
  		dw_dma_cyclic_stop(dac->dma.chan);
  		dac_writel(dac, DATA, 0);
  		dac_writel(dac, CTRL, 0);
  		clk_disable(dac->sample_clk);
  		break;
  	default:
  		retval = -EINVAL;
  		break;
  	}
  out:
  	return retval;
  }
  
  static snd_pcm_uframes_t
  atmel_abdac_pointer(struct snd_pcm_substream *substream)
  {
  	struct atmel_abdac	*dac = snd_pcm_substream_chip(substream);
  	struct snd_pcm_runtime	*runtime = substream->runtime;
  	snd_pcm_uframes_t	frames;
  	unsigned long		bytes;
  
  	bytes = dw_dma_get_src_addr(dac->dma.chan);
  	bytes -= runtime->dma_addr;
  
  	frames = bytes_to_frames(runtime, bytes);
  	if (frames >= runtime->buffer_size)
  		frames -= runtime->buffer_size;
  
  	return frames;
  }
  
  static irqreturn_t abdac_interrupt(int irq, void *dev_id)
  {
  	struct atmel_abdac *dac = dev_id;
  	u32 status;
  
  	status = dac_readl(dac, INT_STATUS);
  	if (status & DAC_BIT(UNDERRUN)) {
  		dev_err(&dac->pdev->dev, "underrun detected\n");
  		dac_writel(dac, INT_CLR, DAC_BIT(UNDERRUN));
  	} else {
  		dev_err(&dac->pdev->dev, "spurious interrupt (status=0x%x)\n",
  			status);
  		dac_writel(dac, INT_CLR, status);
  	}
  
  	return IRQ_HANDLED;
  }
  
  static struct snd_pcm_ops atmel_abdac_ops = {
  	.open		= atmel_abdac_open,
  	.close		= atmel_abdac_close,
  	.ioctl		= snd_pcm_lib_ioctl,
  	.hw_params	= atmel_abdac_hw_params,
  	.hw_free	= atmel_abdac_hw_free,
  	.prepare	= atmel_abdac_prepare,
  	.trigger	= atmel_abdac_trigger,
  	.pointer	= atmel_abdac_pointer,
  };
  
  static int atmel_abdac_pcm_new(struct atmel_abdac *dac)
  {
  	struct snd_pcm_hardware hw = atmel_abdac_hw;
  	struct snd_pcm *pcm;
  	int retval;
  
  	retval = snd_pcm_new(dac->card, dac->card->shortname,
  			dac->pdev->id, 1, 0, &pcm);
  	if (retval)
  		return retval;
  
  	strcpy(pcm->name, dac->card->shortname);
  	pcm->private_data = dac;
  	pcm->info_flags = 0;
  	dac->pcm = pcm;
  
  	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &atmel_abdac_ops);
  
  	retval = snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV,
  			&dac->pdev->dev, hw.periods_min * hw.period_bytes_min,
  			hw.buffer_bytes_max);
  
  	return retval;
  }
  
  static bool filter(struct dma_chan *chan, void *slave)
  {
  	struct dw_dma_slave *dws = slave;
  
  	if (dws->dma_dev == chan->device->dev) {
  		chan->private = dws;
  		return true;
  	} else
  		return false;
  }
  
  static int set_sample_rates(struct atmel_abdac *dac)
  {
  	long new_rate = RATE_MAX;
  	int retval = -EINVAL;
  	int index = 0;
  
  	/* we start at 192 kHz and work our way down to 5112 Hz */
  	while (new_rate >= RATE_MIN && index < (MAX_NUM_RATES + 1)) {
  		new_rate = clk_round_rate(dac->sample_clk, 256 * new_rate);
  		if (new_rate <= 0)
  			break;
  		/* make sure we are below the ABDAC clock */
  		if (index < MAX_NUM_RATES &&
  		    new_rate <= clk_get_rate(dac->pclk)) {
  			dac->rates[index] = new_rate / 256;
  			index++;
  		}
  		/* divide by 256 and then by two to get next rate */
  		new_rate /= 256 * 2;
  	}
  
  	if (index) {
  		int i;
  
  		/* reverse array, smallest go first */
  		for (i = 0; i < (index / 2); i++) {
  			unsigned int tmp = dac->rates[index - 1 - i];
  			dac->rates[index - 1 - i] = dac->rates[i];
  			dac->rates[i] = tmp;
  		}
  
  		dac->constraints_rates.count = index;
  		dac->constraints_rates.list = dac->rates;
  		dac->constraints_rates.mask = 0;
  		dac->rates_num = index;
  
  		retval = 0;
  	}
  
  	return retval;
  }
  
  static int atmel_abdac_probe(struct platform_device *pdev)
  {
  	struct snd_card		*card;
  	struct atmel_abdac	*dac;
  	struct resource		*regs;
  	struct atmel_abdac_pdata	*pdata;
  	struct clk		*pclk;
  	struct clk		*sample_clk;
  	int			retval;
  	int			irq;
  
  	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!regs) {
  		dev_dbg(&pdev->dev, "no memory resource\n");
  		return -ENXIO;
  	}
  
  	irq = platform_get_irq(pdev, 0);
  	if (irq < 0) {
  		dev_dbg(&pdev->dev, "could not get IRQ number\n");
  		return irq;
  	}
  
  	pdata = pdev->dev.platform_data;
  	if (!pdata) {
  		dev_dbg(&pdev->dev, "no platform data\n");
  		return -ENXIO;
  	}
  
  	pclk = clk_get(&pdev->dev, "pclk");
  	if (IS_ERR(pclk)) {
  		dev_dbg(&pdev->dev, "no peripheral clock\n");
  		return PTR_ERR(pclk);
  	}
  	sample_clk = clk_get(&pdev->dev, "sample_clk");
  	if (IS_ERR(sample_clk)) {
  		dev_dbg(&pdev->dev, "no sample clock\n");
  		retval = PTR_ERR(sample_clk);
  		goto out_put_pclk;
  	}
  	clk_enable(pclk);
  
  	retval = snd_card_create(SNDRV_DEFAULT_IDX1, SNDRV_DEFAULT_STR1,
  			THIS_MODULE, sizeof(struct atmel_abdac), &card);
  	if (retval) {
  		dev_dbg(&pdev->dev, "could not create sound card device\n");
  		goto out_put_sample_clk;
  	}
  
  	dac = get_dac(card);
  
  	dac->irq = irq;
  	dac->card = card;
  	dac->pclk = pclk;
  	dac->sample_clk = sample_clk;
  	dac->pdev = pdev;
  
  	retval = set_sample_rates(dac);
  	if (retval < 0) {
  		dev_dbg(&pdev->dev, "could not set supported rates\n");
  		goto out_free_card;
  	}
  
  	dac->regs = ioremap(regs->start, resource_size(regs));
  	if (!dac->regs) {
  		dev_dbg(&pdev->dev, "could not remap register memory\n");
  		retval = -ENOMEM;
  		goto out_free_card;
  	}
  
  	/* make sure the DAC is silent and disabled */
  	dac_writel(dac, DATA, 0);
  	dac_writel(dac, CTRL, 0);
  
  	retval = request_irq(irq, abdac_interrupt, 0, "abdac", dac);
  	if (retval) {
  		dev_dbg(&pdev->dev, "could not request irq\n");
  		goto out_unmap_regs;
  	}
  
  	snd_card_set_dev(card, &pdev->dev);
  
  	if (pdata->dws.dma_dev) {
  		dma_cap_mask_t mask;
  
  		dma_cap_zero(mask);
  		dma_cap_set(DMA_SLAVE, mask);
  
  		dac->dma.chan = dma_request_channel(mask, filter, &pdata->dws);
  		if (dac->dma.chan) {
  			struct dma_slave_config dma_conf = {
  				.dst_addr = regs->start + DAC_DATA,
  				.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES,
  				.src_maxburst = 1,
  				.dst_maxburst = 1,
  				.direction = DMA_MEM_TO_DEV,
  				.device_fc = false,
  			};
  
  			dmaengine_slave_config(dac->dma.chan, &dma_conf);
  		}
  	}
  	if (!pdata->dws.dma_dev || !dac->dma.chan) {
  		dev_dbg(&pdev->dev, "DMA not available\n");
  		retval = -ENODEV;
  		goto out_unset_card_dev;
  	}
  
  	strcpy(card->driver, "Atmel ABDAC");
  	strcpy(card->shortname, "Atmel ABDAC");
  	sprintf(card->longname, "Atmel Audio Bitstream DAC");
  
  	retval = atmel_abdac_pcm_new(dac);
  	if (retval) {
  		dev_dbg(&pdev->dev, "could not register ABDAC pcm device\n");
  		goto out_release_dma;
  	}
  
  	retval = snd_card_register(card);
  	if (retval) {
  		dev_dbg(&pdev->dev, "could not register sound card\n");
  		goto out_release_dma;
  	}
  
  	platform_set_drvdata(pdev, card);
  
  	dev_info(&pdev->dev, "Atmel ABDAC at 0x%p using %s\n",
  			dac->regs, dev_name(&dac->dma.chan->dev->device));
  
  	return retval;
  
  out_release_dma:
  	dma_release_channel(dac->dma.chan);
  	dac->dma.chan = NULL;
  out_unset_card_dev:
  	snd_card_set_dev(card, NULL);
  	free_irq(irq, dac);
  out_unmap_regs:
  	iounmap(dac->regs);
  out_free_card:
  	snd_card_free(card);
  out_put_sample_clk:
  	clk_put(sample_clk);
  	clk_disable(pclk);
  out_put_pclk:
  	clk_put(pclk);
  	return retval;
  }
  
  #ifdef CONFIG_PM_SLEEP
  static int atmel_abdac_suspend(struct device *pdev)
  {
  	struct snd_card *card = dev_get_drvdata(pdev);
  	struct atmel_abdac *dac = card->private_data;
  
  	dw_dma_cyclic_stop(dac->dma.chan);
  	clk_disable(dac->sample_clk);
  	clk_disable(dac->pclk);
  
  	return 0;
  }
  
  static int atmel_abdac_resume(struct device *pdev)
  {
  	struct snd_card *card = dev_get_drvdata(pdev);
  	struct atmel_abdac *dac = card->private_data;
  
  	clk_enable(dac->pclk);
  	clk_enable(dac->sample_clk);
  	if (test_bit(DMA_READY, &dac->flags))
  		dw_dma_cyclic_start(dac->dma.chan);
  
  	return 0;
  }
  
  static SIMPLE_DEV_PM_OPS(atmel_abdac_pm, atmel_abdac_suspend, atmel_abdac_resume);
  #define ATMEL_ABDAC_PM_OPS	&atmel_abdac_pm
  #else
  #define ATMEL_ABDAC_PM_OPS	NULL
  #endif
  
  static int atmel_abdac_remove(struct platform_device *pdev)
  {
  	struct snd_card *card = platform_get_drvdata(pdev);
  	struct atmel_abdac *dac = get_dac(card);
  
  	clk_put(dac->sample_clk);
  	clk_disable(dac->pclk);
  	clk_put(dac->pclk);
  
  	dma_release_channel(dac->dma.chan);
  	dac->dma.chan = NULL;
  	snd_card_set_dev(card, NULL);
  	iounmap(dac->regs);
  	free_irq(dac->irq, dac);
  	snd_card_free(card);
  
  	return 0;
  }
  
  static struct platform_driver atmel_abdac_driver = {
  	.remove		= atmel_abdac_remove,
  	.driver		= {
  		.name	= "atmel_abdac",
  		.owner	= THIS_MODULE,
  		.pm	= ATMEL_ABDAC_PM_OPS,
  	},
  };
  
  static int __init atmel_abdac_init(void)
  {
  	return platform_driver_probe(&atmel_abdac_driver,
  			atmel_abdac_probe);
  }
  module_init(atmel_abdac_init);
  
  static void __exit atmel_abdac_exit(void)
  {
  	platform_driver_unregister(&atmel_abdac_driver);
  }
  module_exit(atmel_abdac_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Driver for Atmel Audio Bitstream DAC (ABDAC)");
  MODULE_AUTHOR("Hans-Christian Egtvedt <egtvedt@samfundet.no>");
  