sound/soc/samsung/pcm.c

/* sound/soc/samsung/pcm.c
 *
 * ALSA SoC Audio Layer - S3C PCM-Controller driver
 *
 * Copyright (c) 2009 Samsung Electronics Co. Ltd
 * Author: Jaswinder Singh <jassisinghbrar@gmail.com>
 * based upon I2S drivers by Ben Dooks.
 *
 * 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/io.h>
#include <linux/module.h>
#include <linux/pm_runtime.h>

#include <sound/soc.h>
#include <sound/pcm_params.h>

#include <linux/platform_data/asoc-s3c.h>

#include "dma.h"
#include "pcm.h"

/*Register Offsets */
#define S3C_PCM_CTL		0x00
#define S3C_PCM_CLKCTL		0x04
#define S3C_PCM_TXFIFO		0x08
#define S3C_PCM_RXFIFO		0x0C
#define S3C_PCM_IRQCTL		0x10
#define S3C_PCM_IRQSTAT		0x14
#define S3C_PCM_FIFOSTAT	0x18
#define S3C_PCM_CLRINT		0x20

/* PCM_CTL Bit-Fields */
#define S3C_PCM_CTL_TXDIPSTICK_MASK	0x3f
#define S3C_PCM_CTL_TXDIPSTICK_SHIFT	13
#define S3C_PCM_CTL_RXDIPSTICK_MASK	0x3f
#define S3C_PCM_CTL_RXDIPSTICK_SHIFT	7
#define S3C_PCM_CTL_TXDMA_EN		(0x1 << 6)
#define S3C_PCM_CTL_RXDMA_EN		(0x1 << 5)
#define S3C_PCM_CTL_TXMSB_AFTER_FSYNC	(0x1 << 4)
#define S3C_PCM_CTL_RXMSB_AFTER_FSYNC	(0x1 << 3)
#define S3C_PCM_CTL_TXFIFO_EN		(0x1 << 2)
#define S3C_PCM_CTL_RXFIFO_EN		(0x1 << 1)
#define S3C_PCM_CTL_ENABLE		(0x1 << 0)

/* PCM_CLKCTL Bit-Fields */
#define S3C_PCM_CLKCTL_SERCLK_EN	(0x1 << 19)
#define S3C_PCM_CLKCTL_SERCLKSEL_PCLK	(0x1 << 18)
#define S3C_PCM_CLKCTL_SCLKDIV_MASK	0x1ff
#define S3C_PCM_CLKCTL_SYNCDIV_MASK	0x1ff
#define S3C_PCM_CLKCTL_SCLKDIV_SHIFT	9
#define S3C_PCM_CLKCTL_SYNCDIV_SHIFT	0

/* PCM_TXFIFO Bit-Fields */
#define S3C_PCM_TXFIFO_DVALID	(0x1 << 16)
#define S3C_PCM_TXFIFO_DATA_MSK	(0xffff << 0)

/* PCM_RXFIFO Bit-Fields */
#define S3C_PCM_RXFIFO_DVALID	(0x1 << 16)
#define S3C_PCM_RXFIFO_DATA_MSK	(0xffff << 0)

/* PCM_IRQCTL Bit-Fields */
#define S3C_PCM_IRQCTL_IRQEN		(0x1 << 14)
#define S3C_PCM_IRQCTL_WRDEN		(0x1 << 12)
#define S3C_PCM_IRQCTL_TXEMPTYEN	(0x1 << 11)
#define S3C_PCM_IRQCTL_TXALMSTEMPTYEN	(0x1 << 10)
#define S3C_PCM_IRQCTL_TXFULLEN		(0x1 << 9)
#define S3C_PCM_IRQCTL_TXALMSTFULLEN	(0x1 << 8)
#define S3C_PCM_IRQCTL_TXSTARVEN	(0x1 << 7)
#define S3C_PCM_IRQCTL_TXERROVRFLEN	(0x1 << 6)
#define S3C_PCM_IRQCTL_RXEMPTEN		(0x1 << 5)
#define S3C_PCM_IRQCTL_RXALMSTEMPTEN	(0x1 << 4)
#define S3C_PCM_IRQCTL_RXFULLEN		(0x1 << 3)
#define S3C_PCM_IRQCTL_RXALMSTFULLEN	(0x1 << 2)
#define S3C_PCM_IRQCTL_RXSTARVEN	(0x1 << 1)
#define S3C_PCM_IRQCTL_RXERROVRFLEN	(0x1 << 0)

/* PCM_IRQSTAT Bit-Fields */
#define S3C_PCM_IRQSTAT_IRQPND		(0x1 << 13)
#define S3C_PCM_IRQSTAT_WRD_XFER	(0x1 << 12)
#define S3C_PCM_IRQSTAT_TXEMPTY		(0x1 << 11)
#define S3C_PCM_IRQSTAT_TXALMSTEMPTY	(0x1 << 10)
#define S3C_PCM_IRQSTAT_TXFULL		(0x1 << 9)
#define S3C_PCM_IRQSTAT_TXALMSTFULL	(0x1 << 8)
#define S3C_PCM_IRQSTAT_TXSTARV		(0x1 << 7)
#define S3C_PCM_IRQSTAT_TXERROVRFL	(0x1 << 6)
#define S3C_PCM_IRQSTAT_RXEMPT		(0x1 << 5)
#define S3C_PCM_IRQSTAT_RXALMSTEMPT	(0x1 << 4)
#define S3C_PCM_IRQSTAT_RXFULL		(0x1 << 3)
#define S3C_PCM_IRQSTAT_RXALMSTFULL	(0x1 << 2)
#define S3C_PCM_IRQSTAT_RXSTARV		(0x1 << 1)
#define S3C_PCM_IRQSTAT_RXERROVRFL	(0x1 << 0)

/* PCM_FIFOSTAT Bit-Fields */
#define S3C_PCM_FIFOSTAT_TXCNT_MSK		(0x3f << 14)
#define S3C_PCM_FIFOSTAT_TXFIFOEMPTY		(0x1 << 13)
#define S3C_PCM_FIFOSTAT_TXFIFOALMSTEMPTY	(0x1 << 12)
#define S3C_PCM_FIFOSTAT_TXFIFOFULL		(0x1 << 11)
#define S3C_PCM_FIFOSTAT_TXFIFOALMSTFULL	(0x1 << 10)
#define S3C_PCM_FIFOSTAT_RXCNT_MSK		(0x3f << 4)
#define S3C_PCM_FIFOSTAT_RXFIFOEMPTY		(0x1 << 3)
#define S3C_PCM_FIFOSTAT_RXFIFOALMSTEMPTY	(0x1 << 2)
#define S3C_PCM_FIFOSTAT_RXFIFOFULL		(0x1 << 1)
#define S3C_PCM_FIFOSTAT_RXFIFOALMSTFULL	(0x1 << 0)

/**
 * struct s3c_pcm_info - S3C PCM Controller information
 * @dev: The parent device passed to use from the probe.
 * @regs: The pointer to the device register block.
 * @dma_playback: DMA information for playback channel.
 * @dma_capture: DMA information for capture channel.
 */
struct s3c_pcm_info {
	spinlock_t lock;
	struct device	*dev;
	void __iomem	*regs;

	unsigned int sclk_per_fs;

	/* Whether to keep PCMSCLK enabled even when idle(no active xfer) */
	unsigned int idleclk;

	struct clk	*pclk;
	struct clk	*cclk;

	struct snd_dmaengine_dai_dma_data *dma_playback;
	struct snd_dmaengine_dai_dma_data *dma_capture;
};

static struct snd_dmaengine_dai_dma_data s3c_pcm_stereo_out[] = {
	[0] = {
		.addr_width	= 4,
	},
	[1] = {
		.addr_width	= 4,
	},
};

static struct snd_dmaengine_dai_dma_data s3c_pcm_stereo_in[] = {
	[0] = {
		.addr_width	= 4,
	},
	[1] = {
		.addr_width	= 4,
	},
};

static struct s3c_pcm_info s3c_pcm[2];

static void s3c_pcm_snd_txctrl(struct s3c_pcm_info *pcm, int on)
{
	void __iomem *regs = pcm->regs;
	u32 ctl, clkctl;

	clkctl = readl(regs + S3C_PCM_CLKCTL);
	ctl = readl(regs + S3C_PCM_CTL);
	ctl &= ~(S3C_PCM_CTL_TXDIPSTICK_MASK
			 << S3C_PCM_CTL_TXDIPSTICK_SHIFT);

	if (on) {
		ctl |= S3C_PCM_CTL_TXDMA_EN;
		ctl |= S3C_PCM_CTL_TXFIFO_EN;
		ctl |= S3C_PCM_CTL_ENABLE;
		ctl |= (0x4<<S3C_PCM_CTL_TXDIPSTICK_SHIFT);
		clkctl |= S3C_PCM_CLKCTL_SERCLK_EN;
	} else {
		ctl &= ~S3C_PCM_CTL_TXDMA_EN;
		ctl &= ~S3C_PCM_CTL_TXFIFO_EN;

		if (!(ctl & S3C_PCM_CTL_RXFIFO_EN)) {
			ctl &= ~S3C_PCM_CTL_ENABLE;
			if (!pcm->idleclk)
				clkctl |= S3C_PCM_CLKCTL_SERCLK_EN;
		}
	}

	writel(clkctl, regs + S3C_PCM_CLKCTL);
	writel(ctl, regs + S3C_PCM_CTL);
}

static void s3c_pcm_snd_rxctrl(struct s3c_pcm_info *pcm, int on)
{
	void __iomem *regs = pcm->regs;
	u32 ctl, clkctl;

	ctl = readl(regs + S3C_PCM_CTL);
	clkctl = readl(regs + S3C_PCM_CLKCTL);
	ctl &= ~(S3C_PCM_CTL_RXDIPSTICK_MASK
			 << S3C_PCM_CTL_RXDIPSTICK_SHIFT);

	if (on) {
		ctl |= S3C_PCM_CTL_RXDMA_EN;
		ctl |= S3C_PCM_CTL_RXFIFO_EN;
		ctl |= S3C_PCM_CTL_ENABLE;
		ctl |= (0x20<<S3C_PCM_CTL_RXDIPSTICK_SHIFT);
		clkctl |= S3C_PCM_CLKCTL_SERCLK_EN;
	} else {
		ctl &= ~S3C_PCM_CTL_RXDMA_EN;
		ctl &= ~S3C_PCM_CTL_RXFIFO_EN;

		if (!(ctl & S3C_PCM_CTL_TXFIFO_EN)) {
			ctl &= ~S3C_PCM_CTL_ENABLE;
			if (!pcm->idleclk)
				clkctl |= S3C_PCM_CLKCTL_SERCLK_EN;
		}
	}

	writel(clkctl, regs + S3C_PCM_CLKCTL);
	writel(ctl, regs + S3C_PCM_CTL);
}

static int s3c_pcm_trigger(struct snd_pcm_substream *substream, int cmd,
			       struct snd_soc_dai *dai)
{
	struct snd_soc_pcm_runtime *rtd = substream->private_data;
	struct s3c_pcm_info *pcm = snd_soc_dai_get_drvdata(rtd->cpu_dai);
	unsigned long flags;

	dev_dbg(pcm->dev, "Entered %s\n", __func__);

	switch (cmd) {
	case SNDRV_PCM_TRIGGER_START:
	case SNDRV_PCM_TRIGGER_RESUME:
	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
		spin_lock_irqsave(&pcm->lock, flags);

		if (substream->stream == SNDRV_PCM_STREAM_CAPTURE)
			s3c_pcm_snd_rxctrl(pcm, 1);
		else
			s3c_pcm_snd_txctrl(pcm, 1);

		spin_unlock_irqrestore(&pcm->lock, flags);
		break;

	case SNDRV_PCM_TRIGGER_STOP:
	case SNDRV_PCM_TRIGGER_SUSPEND:
	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
		spin_lock_irqsave(&pcm->lock, flags);

		if (substream->stream == SNDRV_PCM_STREAM_CAPTURE)
			s3c_pcm_snd_rxctrl(pcm, 0);
		else
			s3c_pcm_snd_txctrl(pcm, 0);

		spin_unlock_irqrestore(&pcm->lock, flags);
		break;

	default:
		return -EINVAL;
	}

	return 0;
}

static int s3c_pcm_hw_params(struct snd_pcm_substream *substream,
				 struct snd_pcm_hw_params *params,
				 struct snd_soc_dai *socdai)
{
	struct snd_soc_pcm_runtime *rtd = substream->private_data;
	struct s3c_pcm_info *pcm = snd_soc_dai_get_drvdata(rtd->cpu_dai);
	void __iomem *regs = pcm->regs;
	struct clk *clk;
	int sclk_div, sync_div;
	unsigned long flags;
	u32 clkctl;

	dev_dbg(pcm->dev, "Entered %s\n", __func__);

	/* Strictly check for sample size */
	switch (params_width(params)) {
	case 16:
		break;
	default:
		return -EINVAL;
	}

	spin_lock_irqsave(&pcm->lock, flags);

	/* Get hold of the PCMSOURCE_CLK */
	clkctl = readl(regs + S3C_PCM_CLKCTL);
	if (clkctl & S3C_PCM_CLKCTL_SERCLKSEL_PCLK)
		clk = pcm->pclk;
	else
		clk = pcm->cclk;

	/* Set the SCLK divider */
	sclk_div = clk_get_rate(clk) / pcm->sclk_per_fs /
					params_rate(params) / 2 - 1;

	clkctl &= ~(S3C_PCM_CLKCTL_SCLKDIV_MASK
			<< S3C_PCM_CLKCTL_SCLKDIV_SHIFT);
	clkctl |= ((sclk_div & S3C_PCM_CLKCTL_SCLKDIV_MASK)
			<< S3C_PCM_CLKCTL_SCLKDIV_SHIFT);

	/* Set the SYNC divider */
	sync_div = pcm->sclk_per_fs - 1;

	clkctl &= ~(S3C_PCM_CLKCTL_SYNCDIV_MASK
				<< S3C_PCM_CLKCTL_SYNCDIV_SHIFT);
	clkctl |= ((sync_div & S3C_PCM_CLKCTL_SYNCDIV_MASK)
				<< S3C_PCM_CLKCTL_SYNCDIV_SHIFT);

	writel(clkctl, regs + S3C_PCM_CLKCTL);

	spin_unlock_irqrestore(&pcm->lock, flags);

	dev_dbg(pcm->dev, "PCMSOURCE_CLK-%lu SCLK=%ufs SCLK_DIV=%d SYNC_DIV=%d\n",
				clk_get_rate(clk), pcm->sclk_per_fs,
				sclk_div, sync_div);

	return 0;
}

static int s3c_pcm_set_fmt(struct snd_soc_dai *cpu_dai,
			       unsigned int fmt)
{
	struct s3c_pcm_info *pcm = snd_soc_dai_get_drvdata(cpu_dai);
	void __iomem *regs = pcm->regs;
	unsigned long flags;
	int ret = 0;
	u32 ctl;

	dev_dbg(pcm->dev, "Entered %s\n", __func__);

	spin_lock_irqsave(&pcm->lock, flags);

	ctl = readl(regs + S3C_PCM_CTL);

	switch (fmt & SND_SOC_DAIFMT_INV_MASK) {
	case SND_SOC_DAIFMT_IB_NF:
		/* Nothing to do, IB_NF by default */
		break;
	default:
		dev_err(pcm->dev, "Unsupported clock inversion!\n");
		ret = -EINVAL;
		goto exit;
	}

	switch (fmt & SND_SOC_DAIFMT_MASTER_MASK) {
	case SND_SOC_DAIFMT_CBS_CFS:
		/* Nothing to do, Master by default */
		break;
	default:
		dev_err(pcm->dev, "Unsupported master/slave format!\n");
		ret = -EINVAL;
		goto exit;
	}

	switch (fmt & SND_SOC_DAIFMT_CLOCK_MASK) {
	case SND_SOC_DAIFMT_CONT:
		pcm->idleclk = 1;
		break;
	case SND_SOC_DAIFMT_GATED:
		pcm->idleclk = 0;
		break;
	default:
		dev_err(pcm->dev, "Invalid Clock gating request!\n");
		ret = -EINVAL;
		goto exit;
	}

	switch (fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
	case SND_SOC_DAIFMT_DSP_A:
		ctl |= S3C_PCM_CTL_TXMSB_AFTER_FSYNC;
		ctl |= S3C_PCM_CTL_RXMSB_AFTER_FSYNC;
		break;
	case SND_SOC_DAIFMT_DSP_B:
		ctl &= ~S3C_PCM_CTL_TXMSB_AFTER_FSYNC;
		ctl &= ~S3C_PCM_CTL_RXMSB_AFTER_FSYNC;
		break;
	default:
		dev_err(pcm->dev, "Unsupported data format!\n");
		ret = -EINVAL;
		goto exit;
	}

	writel(ctl, regs + S3C_PCM_CTL);

exit:
	spin_unlock_irqrestore(&pcm->lock, flags);

	return ret;
}

static int s3c_pcm_set_clkdiv(struct snd_soc_dai *cpu_dai,
						int div_id, int div)
{
	struct s3c_pcm_info *pcm = snd_soc_dai_get_drvdata(cpu_dai);

	switch (div_id) {
	case S3C_PCM_SCLK_PER_FS:
		pcm->sclk_per_fs = div;
		break;

	default:
		return -EINVAL;
	}

	return 0;
}

static int s3c_pcm_set_sysclk(struct snd_soc_dai *cpu_dai,
				  int clk_id, unsigned int freq, int dir)
{
	struct s3c_pcm_info *pcm = snd_soc_dai_get_drvdata(cpu_dai);
	void __iomem *regs = pcm->regs;
	u32 clkctl = readl(regs + S3C_PCM_CLKCTL);

	switch (clk_id) {
	case S3C_PCM_CLKSRC_PCLK:
		clkctl |= S3C_PCM_CLKCTL_SERCLKSEL_PCLK;
		break;

	case S3C_PCM_CLKSRC_MUX:
		clkctl &= ~S3C_PCM_CLKCTL_SERCLKSEL_PCLK;

		if (clk_get_rate(pcm->cclk) != freq)
			clk_set_rate(pcm->cclk, freq);

		break;

	default:
		return -EINVAL;
	}

	writel(clkctl, regs + S3C_PCM_CLKCTL);

	return 0;
}

static const struct snd_soc_dai_ops s3c_pcm_dai_ops = {
	.set_sysclk	= s3c_pcm_set_sysclk,
	.set_clkdiv	= s3c_pcm_set_clkdiv,
	.trigger	= s3c_pcm_trigger,
	.hw_params	= s3c_pcm_hw_params,
	.set_fmt	= s3c_pcm_set_fmt,
};

static int s3c_pcm_dai_probe(struct snd_soc_dai *dai)
{
	struct s3c_pcm_info *pcm = snd_soc_dai_get_drvdata(dai);

	snd_soc_dai_init_dma_data(dai, pcm->dma_playback, pcm->dma_capture);

	return 0;
}

#define S3C_PCM_RATES  SNDRV_PCM_RATE_8000_96000

#define S3C_PCM_DAI_DECLARE			\
	.symmetric_rates = 1,					\
	.probe = s3c_pcm_dai_probe,				\
	.ops = &s3c_pcm_dai_ops,				\
	.playback = {						\
		.channels_min	= 2,				\
		.channels_max	= 2,				\
		.rates		= S3C_PCM_RATES,		\
		.formats	= SNDRV_PCM_FMTBIT_S16_LE,	\
	},							\
	.capture = {						\
		.channels_min	= 2,				\
		.channels_max	= 2,				\
		.rates		= S3C_PCM_RATES,		\
		.formats	= SNDRV_PCM_FMTBIT_S16_LE,	\
	}

static struct snd_soc_dai_driver s3c_pcm_dai[] = {
	[0] = {
		.name	= "samsung-pcm.0",
		S3C_PCM_DAI_DECLARE,
	},
	[1] = {
		.name	= "samsung-pcm.1",
		S3C_PCM_DAI_DECLARE,
	},
};

static const struct snd_soc_component_driver s3c_pcm_component = {
	.name		= "s3c-pcm",
};

static int s3c_pcm_dev_probe(struct platform_device *pdev)
{
	struct s3c_pcm_info *pcm;
	struct resource *mem_res;
	struct s3c_audio_pdata *pcm_pdata;
	dma_filter_fn filter;
	int ret;

	/* Check for valid device index */
	if ((pdev->id < 0) || pdev->id >= ARRAY_SIZE(s3c_pcm)) {
		dev_err(&pdev->dev, "id %d out of range\n", pdev->id);
		return -EINVAL;
	}

	pcm_pdata = pdev->dev.platform_data;

	if (pcm_pdata && pcm_pdata->cfg_gpio && pcm_pdata->cfg_gpio(pdev)) {
		dev_err(&pdev->dev, "Unable to configure gpio\n");
		return -EINVAL;
	}

	pcm = &s3c_pcm[pdev->id];
	pcm->dev = &pdev->dev;

	spin_lock_init(&pcm->lock);

	/* Default is 128fs */
	pcm->sclk_per_fs = 128;

	mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	pcm->regs = devm_ioremap_resource(&pdev->dev, mem_res);
	if (IS_ERR(pcm->regs))
		return PTR_ERR(pcm->regs);

	pcm->cclk = devm_clk_get(&pdev->dev, "audio-bus");
	if (IS_ERR(pcm->cclk)) {
		dev_err(&pdev->dev, "failed to get audio-bus clock\n");
		return PTR_ERR(pcm->cclk);
	}
	ret = clk_prepare_enable(pcm->cclk);
	if (ret)
		return ret;

	/* record our pcm structure for later use in the callbacks */
	dev_set_drvdata(&pdev->dev, pcm);

	pcm->pclk = devm_clk_get(&pdev->dev, "pcm");
	if (IS_ERR(pcm->pclk)) {
		dev_err(&pdev->dev, "failed to get pcm clock\n");
		ret = PTR_ERR(pcm->pclk);
		goto err_dis_cclk;
	}
	ret = clk_prepare_enable(pcm->pclk);
	if (ret)
		goto err_dis_cclk;

	s3c_pcm_stereo_in[pdev->id].addr = mem_res->start + S3C_PCM_RXFIFO;
	s3c_pcm_stereo_out[pdev->id].addr = mem_res->start + S3C_PCM_TXFIFO;

	filter = NULL;
	if (pcm_pdata) {
		s3c_pcm_stereo_in[pdev->id].filter_data = pcm_pdata->dma_capture;
		s3c_pcm_stereo_out[pdev->id].filter_data = pcm_pdata->dma_playback;
		filter = pcm_pdata->dma_filter;
	}

	pcm->dma_capture = &s3c_pcm_stereo_in[pdev->id];
	pcm->dma_playback = &s3c_pcm_stereo_out[pdev->id];

	ret = samsung_asoc_dma_platform_register(&pdev->dev, filter,
						 NULL, NULL, NULL);
	if (ret) {
		dev_err(&pdev->dev, "failed to get register DMA: %d\n", ret);
		goto err_dis_pclk;
	}

	pm_runtime_enable(&pdev->dev);

	ret = devm_snd_soc_register_component(&pdev->dev, &s3c_pcm_component,
					 &s3c_pcm_dai[pdev->id], 1);
	if (ret != 0) {
		dev_err(&pdev->dev, "failed to get register DAI: %d\n", ret);
		goto err_dis_pm;
	}

	return 0;

err_dis_pm:
	pm_runtime_disable(&pdev->dev);
err_dis_pclk:
	clk_disable_unprepare(pcm->pclk);
err_dis_cclk:
	clk_disable_unprepare(pcm->cclk);
	return ret;
}

static int s3c_pcm_dev_remove(struct platform_device *pdev)
{
	struct s3c_pcm_info *pcm = &s3c_pcm[pdev->id];

	pm_runtime_disable(&pdev->dev);
	clk_disable_unprepare(pcm->cclk);
	clk_disable_unprepare(pcm->pclk);

	return 0;
}

static struct platform_driver s3c_pcm_driver = {
	.probe  = s3c_pcm_dev_probe,
	.remove = s3c_pcm_dev_remove,
	.driver = {
		.name = "samsung-pcm",
	},
};

module_platform_driver(s3c_pcm_driver);

/* Module information */
MODULE_AUTHOR("Jaswinder Singh, <jassisinghbrar@gmail.com>");
MODULE_DESCRIPTION("S3C PCM Controller Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:samsung-pcm");