mmc_spi.c

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			dev_dbg(&host->spi->dev, "bogus command\n");
			cmd->error = -EINVAL;
			invalid = 1;
		}

		cmd = mrq->stop;
		if (cmd && !mmc_spi_resp_type(cmd)) {
			dev_dbg(&host->spi->dev, "bogus STOP command\n");
			cmd->error = -EINVAL;
			invalid = 1;
		}

		if (invalid) {
			dump_stack();
			mmc_request_done(host->mmc, mrq);
			return;
		}
	}
#endif

	/* issue command; then optionally data and stop */
	status = mmc_spi_command_send(host, mrq, mrq->cmd, mrq->data != NULL);
	if (status == 0 && mrq->data) {
		mmc_spi_data_do(host, mrq->cmd, mrq->data, mrq->data->blksz);
		if (mrq->stop)
			status = mmc_spi_command_send(host, mrq, mrq->stop, 0);
		else
			mmc_cs_off(host);
	}

	mmc_request_done(host->mmc, mrq);
}

/* See Section 6.4.1, in SD "Simplified Physical Layer Specification 2.0"
 *
 * NOTE that here we can't know that the card has just been powered up;
 * not all MMC/SD sockets support power switching.
 *
 * FIXME when the card is still in SPI mode, e.g. from a previous kernel,
 * this doesn't seem to do the right thing at all...
 */
static void mmc_spi_initsequence(struct mmc_spi_host *host)
{
	/* Try to be very sure any previous command has completed;
	 * wait till not-busy, skip debris from any old commands.
	 */
	mmc_spi_wait_unbusy(host, r1b_timeout);
	mmc_spi_readbytes(host, 10);

	/*
	 * Do a burst with chipselect active-high.  We need to do this to
	 * meet the requirement of 74 clock cycles with both chipselect
	 * and CMD (MOSI) high before CMD0 ... after the card has been
	 * powered up to Vdd(min), and so is ready to take commands.
	 *
	 * Some cards are particularly needy of this (e.g. Viking "SD256")
	 * while most others don't seem to care.
	 *
	 * Note that this is one of the places MMC/SD plays games with the
	 * SPI protocol.  Another is that when chipselect is released while
	 * the card returns BUSY status, the clock must issue several cycles
	 * with chipselect high before the card will stop driving its output.
	 */
	host->spi->mode |= SPI_CS_HIGH;
	if (spi_setup(host->spi) != 0) {
		/* Just warn; most cards work without it. */
		dev_warn(&host->spi->dev,
				"can't change chip-select polarity\n");
		host->spi->mode &= ~SPI_CS_HIGH;
	} else {
		mmc_spi_readbytes(host, 18);

		host->spi->mode &= ~SPI_CS_HIGH;
		if (spi_setup(host->spi) != 0) {
			/* Wot, we can't get the same setup we had before? */
			dev_err(&host->spi->dev,
					"can't restore chip-select polarity\n");
		}
	}
}

static char *mmc_powerstring(u8 power_mode)
{
	switch (power_mode) {
	case MMC_POWER_OFF: return "off";
	case MMC_POWER_UP:  return "up";
	case MMC_POWER_ON:  return "on";
	}
	return "?";
}

static void mmc_spi_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
{
	struct mmc_spi_host *host = mmc_priv(mmc);

	if (host->power_mode != ios->power_mode) {
		int		canpower;

		canpower = host->pdata && host->pdata->setpower;

		dev_dbg(&host->spi->dev, "mmc_spi: power %s (%d)%s\n",
				mmc_powerstring(ios->power_mode),
				ios->vdd,
				canpower ? ", can switch" : "");

		/* switch power on/off if possible, accounting for
		 * max 250msec powerup time if needed.
		 */
		if (canpower) {
			switch (ios->power_mode) {
			case MMC_POWER_OFF:
			case MMC_POWER_UP:
				host->pdata->setpower(&host->spi->dev,
						ios->vdd);
				if (ios->power_mode == MMC_POWER_UP)
					msleep(host->powerup_msecs);
			}
		}

		/* See 6.4.1 in the simplified SD card physical spec 2.0 */
		if (ios->power_mode == MMC_POWER_ON)
			mmc_spi_initsequence(host);

		/* If powering down, ground all card inputs to avoid power
		 * delivery from data lines!  On a shared SPI bus, this
		 * will probably be temporary; 6.4.2 of the simplified SD
		 * spec says this must last at least 1msec.
		 *
		 *   - Clock low means CPOL 0, e.g. mode 0
		 *   - MOSI low comes from writing zero
		 *   - Chipselect is usually active low...
		 */
		if (canpower && ios->power_mode == MMC_POWER_OFF) {
			int mres;

			host->spi->mode &= ~(SPI_CPOL|SPI_CPHA);
			mres = spi_setup(host->spi);
			if (mres < 0)
				dev_dbg(&host->spi->dev,
					"switch to SPI mode 0 failed\n");

			if (spi_w8r8(host->spi, 0x00) < 0)
				dev_dbg(&host->spi->dev,
					"put spi signals to low failed\n");

			/*
			 * Now clock should be low due to spi mode 0;
			 * MOSI should be low because of written 0x00;
			 * chipselect should be low (it is active low)
			 * power supply is off, so now MMC is off too!
			 *
			 * FIXME no, chipselect can be high since the
			 * device is inactive and SPI_CS_HIGH is clear...
			 */
			msleep(10);
			if (mres == 0) {
				host->spi->mode |= (SPI_CPOL|SPI_CPHA);
				mres = spi_setup(host->spi);
				if (mres < 0)
					dev_dbg(&host->spi->dev,
						"switch back to SPI mode 3"
						" failed\n");
			}
		}

		host->power_mode = ios->power_mode;
	}

	if (host->spi->max_speed_hz != ios->clock && ios->clock != 0) {
		int		status;

		host->spi->max_speed_hz = ios->clock;
		status = spi_setup(host->spi);
		dev_dbg(&host->spi->dev,
			"mmc_spi:  clock to %d Hz, %d\n",
			host->spi->max_speed_hz, status);
	}
}

static int mmc_spi_get_ro(struct mmc_host *mmc)
{
	struct mmc_spi_host *host = mmc_priv(mmc);

	if (host->pdata && host->pdata->get_ro)
		return host->pdata->get_ro(mmc->parent);
	/* board doesn't support read only detection; assume writeable */
	return 0;
}


static const struct mmc_host_ops mmc_spi_ops = {
	.request	= mmc_spi_request,
	.set_ios	= mmc_spi_set_ios,
	.get_ro		= mmc_spi_get_ro,
};


/****************************************************************************/

/*
 * SPI driver implementation
 */

static irqreturn_t
mmc_spi_detect_irq(int irq, void *mmc)
{
	struct mmc_spi_host *host = mmc_priv(mmc);
	u16 delay_msec = max(host->pdata->detect_delay, (u16)100);

	mmc_detect_change(mmc, msecs_to_jiffies(delay_msec));
	return IRQ_HANDLED;
}

struct count_children {
	unsigned	n;
	struct bus_type	*bus;
};

static int maybe_count_child(struct device *dev, void *c)
{
	struct count_children *ccp = c;

	if (dev->bus == ccp->bus) {
		if (ccp->n)
			return -EBUSY;
		ccp->n++;
	}
	return 0;
}

static int mmc_spi_probe(struct spi_device *spi)
{
	void			*ones;
	struct mmc_host		*mmc;
	struct mmc_spi_host	*host;
	int			status;

	/* MMC and SD specs only seem to care that sampling is on the
	 * rising edge ... meaning SPI modes 0 or 3.  So either SPI mode
	 * should be legit.  We'll use mode 0 since it seems to be a
	 * bit less troublesome on some hardware ... unclear why.
	 */
	spi->mode = SPI_MODE_0;
	spi->bits_per_word = 8;

	status = spi_setup(spi);
	if (status < 0) {
		dev_dbg(&spi->dev, "needs SPI mode %02x, %d KHz; %d\n",
				spi->mode, spi->max_speed_hz / 1000,
				status);
		return status;
	}

	/* We can use the bus safely iff nobody else will interfere with us.
	 * Most commands consist of one SPI message to issue a command, then
	 * several more to collect its response, then possibly more for data
	 * transfer.  Clocking access to other devices during that period will
	 * corrupt the command execution.
	 *
	 * Until we have software primitives which guarantee non-interference,
	 * we'll aim for a hardware-level guarantee.
	 *
	 * REVISIT we can't guarantee another device won't be added later...
	 */
	if (spi->master->num_chipselect > 1) {
		struct count_children cc;

		cc.n = 0;
		cc.bus = spi->dev.bus;
		status = device_for_each_child(spi->dev.parent, &cc,
				maybe_count_child);
		if (status < 0) {
			dev_err(&spi->dev, "can't share SPI bus\n");
			return status;
		}

		dev_warn(&spi->dev, "ASSUMING SPI bus stays unshared!\n");
	}

	/* We need a supply of ones to transmit.  This is the only time
	 * the CPU touches these, so cache coherency isn't a concern.
	 *
	 * NOTE if many systems use more than one MMC-over-SPI connector
	 * it'd save some memory to share this.  That's evidently rare.
	 */
	status = -ENOMEM;
	ones = kmalloc(MMC_SPI_BLOCKSIZE, GFP_KERNEL);
	if (!ones)
		goto nomem;
	memset(ones, 0xff, MMC_SPI_BLOCKSIZE);

	mmc = mmc_alloc_host(sizeof(*host), &spi->dev);
	if (!mmc)
		goto nomem;

	mmc->ops = &mmc_spi_ops;
	mmc->max_blk_size = MMC_SPI_BLOCKSIZE;

	/* As long as we keep track of the number of successfully
	 * transmitted blocks, we're good for multiwrite.
	 */
	mmc->caps = MMC_CAP_SPI | MMC_CAP_MULTIWRITE;

	/* SPI doesn't need the lowspeed device identification thing for
	 * MMC or SD cards, since it never comes up in open drain mode.
	 * That's good; some SPI masters can't handle very low speeds!
	 *
	 * However, low speed SDIO cards need not handle over 400 KHz;
	 * that's the only reason not to use a few MHz for f_min (until
	 * the upper layer reads the target frequency from the CSD).
	 */
	mmc->f_min = 400000;
	mmc->f_max = spi->max_speed_hz;

	host = mmc_priv(mmc);
	host->mmc = mmc;
	host->spi = spi;

	host->ones = ones;

	/* Platform data is used to hook up things like card sensing
	 * and power switching gpios.
	 */
	host->pdata = spi->dev.platform_data;
	if (host->pdata)
		mmc->ocr_avail = host->pdata->ocr_mask;
	if (!mmc->ocr_avail) {
		dev_warn(&spi->dev, "ASSUMING 3.2-3.4 V slot power\n");
		mmc->ocr_avail = MMC_VDD_32_33|MMC_VDD_33_34;
	}
	if (host->pdata && host->pdata->setpower) {
		host->powerup_msecs = host->pdata->powerup_msecs;
		if (!host->powerup_msecs || host->powerup_msecs > 250)
			host->powerup_msecs = 250;
	}

	dev_set_drvdata(&spi->dev, mmc);

	/* preallocate dma buffers */
	host->data = kmalloc(sizeof(*host->data), GFP_KERNEL);
	if (!host->data)
		goto fail_nobuf1;

	if (spi->master->dev.parent->dma_mask) {
		struct device	*dev = spi->master->dev.parent;

		host->dma_dev = dev;
		host->ones_dma = dma_map_single(dev, ones,
				MMC_SPI_BLOCKSIZE, DMA_TO_DEVICE);
		host->data_dma = dma_map_single(dev, host->data,
				sizeof(*host->data), DMA_BIDIRECTIONAL);

		/* REVISIT in theory those map operations can fail... */

		dma_sync_single_for_cpu(host->dma_dev,
				host->data_dma, sizeof(*host->data),
				DMA_BIDIRECTIONAL);
	}

	/* setup message for status/busy readback */
	spi_message_init(&host->readback);
	host->readback.is_dma_mapped = (host->dma_dev != NULL);

	spi_message_add_tail(&host->status, &host->readback);
	host->status.tx_buf = host->ones;
	host->status.tx_dma = host->ones_dma;
	host->status.rx_buf = &host->data->status;
	host->status.rx_dma = host->data_dma + offsetof(struct scratch, status);
	host->status.cs_change = 1;

	/* register card detect irq */
	if (host->pdata && host->pdata->init) {
		status = host->pdata->init(&spi->dev, mmc_spi_detect_irq, mmc);
		if (status != 0)
			goto fail_glue_init;
	}

	status = mmc_add_host(mmc);
	if (status != 0)
		goto fail_add_host;

	dev_info(&spi->dev, "SD/MMC host %s%s%s%s\n",
			mmc->class_dev.bus_id,
			host->dma_dev ? "" : ", no DMA",
			(host->pdata && host->pdata->get_ro)
				? "" : ", no WP",
			(host->pdata && host->pdata->setpower)
				? "" : ", no poweroff");
	return 0;

fail_add_host:
	mmc_remove_host (mmc);
fail_glue_init:
	if (host->dma_dev)
		dma_unmap_single(host->dma_dev, host->data_dma,
				sizeof(*host->data), DMA_BIDIRECTIONAL);
	kfree(host->data);

fail_nobuf1:
	mmc_free_host(mmc);
	dev_set_drvdata(&spi->dev, NULL);

nomem:
	kfree(ones);
	return status;
}


static int __devexit mmc_spi_remove(struct spi_device *spi)
{
	struct mmc_host		*mmc = dev_get_drvdata(&spi->dev);
	struct mmc_spi_host	*host;

	if (mmc) {
		host = mmc_priv(mmc);

		/* prevent new mmc_detect_change() calls */
		if (host->pdata && host->pdata->exit)
			host->pdata->exit(&spi->dev, mmc);

		mmc_remove_host(mmc);

		if (host->dma_dev) {
			dma_unmap_single(host->dma_dev, host->ones_dma,
				MMC_SPI_BLOCKSIZE, DMA_TO_DEVICE);
			dma_unmap_single(host->dma_dev, host->data_dma,
				sizeof(*host->data), DMA_BIDIRECTIONAL);
		}

		kfree(host->data);
		kfree(host->ones);

		spi->max_speed_hz = mmc->f_max;
		mmc_free_host(mmc);
		dev_set_drvdata(&spi->dev, NULL);
	}
	return 0;
}


static struct spi_driver mmc_spi_driver = {
	.driver = {
		.name =		"mmc_spi",
		.bus =		&spi_bus_type,
		.owner =	THIS_MODULE,
	},
	.probe =	mmc_spi_probe,
	.remove =	__devexit_p(mmc_spi_remove),
};


static int __init mmc_spi_init(void)
{
	return spi_register_driver(&mmc_spi_driver);
}
module_init(mmc_spi_init);


static void __exit mmc_spi_exit(void)
{
	spi_unregister_driver(&mmc_spi_driver);
}
module_exit(mmc_spi_exit);


MODULE_AUTHOR("Mike Lavender, David Brownell, "
		"Hans-Peter Nilsson, Jan Nikitenko");
MODULE_DESCRIPTION("SPI SD/MMC host driver");
MODULE_LICENSE("GPL");