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13:23:05 -0400 SPI: omap2_mcspi driver' href='/cgit/cgit.cgi/litmus-rt-ext-res.git/commit/drivers/spi/omap2_mcspi.c?id=ccdc7bf925731ef37f0af95262d675b74544932f'>ccdc7bf92573

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/*
 * OMAP2 McSPI controller driver
 *
 * Copyright (C) 2005, 2006 Nokia Corporation
 * Author:	Samuel Ortiz <samuel.ortiz@nokia.com> and
 *		Juha Yrj�l� <juha.yrjola@nokia.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */

#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/omap-dma.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/pm_runtime.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/gcd.h>

#include <linux/spi/spi.h>

#include <linux/platform_data/spi-omap2-mcspi.h>

#define OMAP2_MCSPI_MAX_FREQ		48000000
#define OMAP2_MCSPI_MAX_DIVIDER		4096
#define OMAP2_MCSPI_MAX_FIFODEPTH	64
#define OMAP2_MCSPI_MAX_FIFOWCNT	0xFFFF
#define SPI_AUTOSUSPEND_TIMEOUT		2000

#define OMAP2_MCSPI_REVISION		0x00
#define OMAP2_MCSPI_SYSSTATUS		0x14
#define OMAP2_MCSPI_IRQSTATUS		0x18
#define OMAP2_MCSPI_IRQENABLE		0x1c
#define OMAP2_MCSPI_WAKEUPENABLE	0x20
#define OMAP2_MCSPI_SYST		0x24
#define OMAP2_MCSPI_MODULCTRL		0x28
#define OMAP2_MCSPI_XFERLEVEL		0x7c

/* per-channel banks, 0x14 bytes each, first is: */
#define OMAP2_MCSPI_CHCONF0		0x2c
#define OMAP2_MCSPI_CHSTAT0		0x30
#define OMAP2_MCSPI_CHCTRL0		0x34
#define OMAP2_MCSPI_TX0			0x38
#define OMAP2_MCSPI_RX0			0x3c

/* per-register bitmasks: */
#define OMAP2_MCSPI_IRQSTATUS_EOW	BIT(17)

#define OMAP2_MCSPI_MODULCTRL_SINGLE	BIT(0)
#define OMAP2_MCSPI_MODULCTRL_MS	BIT(2)
#define OMAP2_MCSPI_MODULCTRL_STEST	BIT(3)

#define OMAP2_MCSPI_CHCONF_PHA		BIT(0)
#define OMAP2_MCSPI_CHCONF_POL		BIT(1)
#define OMAP2_MCSPI_CHCONF_CLKD_MASK	(0x0f << 2)
#define OMAP2_MCSPI_CHCONF_EPOL		BIT(6)
#define OMAP2_MCSPI_CHCONF_WL_MASK	(0x1f << 7)
#define OMAP2_MCSPI_CHCONF_TRM_RX_ONLY	BIT(12)
#define OMAP2_MCSPI_CHCONF_TRM_TX_ONLY	BIT(13)
#define OMAP2_MCSPI_CHCONF_TRM_MASK	(0x03 << 12)
#define OMAP2_MCSPI_CHCONF_DMAW		BIT(14)
#define OMAP2_MCSPI_CHCONF_DMAR		BIT(15)
#define OMAP2_MCSPI_CHCONF_DPE0		BIT(16)
#define OMAP2_MCSPI_CHCONF_DPE1		BIT(17)
#define OMAP2_MCSPI_CHCONF_IS		BIT(18)
#define OMAP2_MCSPI_CHCONF_TURBO	BIT(19)
#define OMAP2_MCSPI_CHCONF_FORCE	BIT(20)
#define OMAP2_MCSPI_CHCONF_FFET		BIT(27)
#define OMAP2_MCSPI_CHCONF_FFER		BIT(28)
#define OMAP2_MCSPI_CHCONF_CLKG		BIT(29)

#define OMAP2_MCSPI_CHSTAT_RXS		BIT(0)
#define OMAP2_MCSPI_CHSTAT_TXS		BIT(1)
#define OMAP2_MCSPI_CHSTAT_EOT		BIT(2)
#define OMAP2_MCSPI_CHSTAT_TXFFE	BIT(3)

#define OMAP2_MCSPI_CHCTRL_EN		BIT(0)
#define OMAP2_MCSPI_CHCTRL_EXTCLK_MASK	(0xff << 8)

#define OMAP2_MCSPI_WAKEUPENABLE_WKEN	BIT(0)

/* We have 2 DMA channels per CS, one for RX and one for TX */
struct omap2_mcspi_dma {
	struct dma_chan *dma_tx;
	struct dma_chan *dma_rx;

	int dma_tx_sync_dev;
	int dma_rx_sync_dev;

	struct completion dma_tx_completion;
	struct completion dma_rx_completion;

	char dma_rx_ch_name[14];
	char dma_tx_ch_name[14];
};

/* use PIO for small transfers, avoiding DMA setup/teardown overhead and
 * cache operations; better heuristics consider wordsize and bitrate.
 */
#define DMA_MIN_BYTES			160


/*
 * Used for context save and restore, structure members to be updated whenever
 * corresponding registers are modified.
 */
struct omap2_mcspi_regs {
	u32 modulctrl;
	u32 wakeupenable;
	struct list_head cs;
};

struct omap2_mcspi {
	struct spi_master	*master;
	/* Virtual base address of the controller */
	void __iomem		*base;
	unsigned long		phys;
	/* SPI1 has 4 channels, while SPI2 has 2 */
	struct omap2_mcspi_dma	*dma_channels;
	struct device		*dev;
	struct omap2_mcspi_regs ctx;
	int			fifo_depth;
	unsigned int		pin_dir:1;
};

struct omap2_mcspi_cs {
	void __iomem		*base;
	unsigned long		phys;
	int			word_len;
	u16			mode;
	struct list_head	node;
	/* Context save and restore shadow register */
	u32			chconf0, chctrl0;
};

static inline void mcspi_write_reg(struct spi_master *master,
		int idx, u32 val)
{
	struct omap2_mcspi *mcspi = spi_master_get_devdata(master);

	writel_relaxed(val, mcspi->base + idx);
}

static inline u32 mcspi_read_reg(struct spi_master *master, int idx)
{
	struct omap2_mcspi *mcspi = spi_master_get_devdata(master);

	return readl_relaxed(mcspi->base + idx);
}

static inline void mcspi_write_cs_reg(const struct spi_device *spi,
		int idx, u32 val)
{
	struct omap2_mcspi_cs	*cs = spi->controller_state;

	writel_relaxed(val, cs->base +  idx);
}

static inline u32 mcspi_read_cs_reg(const struct spi_device *spi, int idx)
{
	struct omap2_mcspi_cs	*cs = spi->controller_state;

	return readl_relaxed(cs->base + idx);
}

static inline u32 mcspi_cached_chconf0(const struct spi_device *spi)
{
	struct omap2_mcspi_cs *cs = spi->controller_state;

	return cs->chconf0;
}

static inline void mcspi_write_chconf0(const struct spi_device *spi, u32 val)
{
	struct omap2_mcspi_cs *cs = spi->controller_state;

	cs->chconf0 = val;
	mcspi_write_cs_reg(spi, OMAP2_MCSPI_CHCONF0, val);
	mcspi_read_cs_reg(spi, OMAP2_MCSPI_CHCONF0);
}

static inline int mcspi_bytes_per_word(int word_len)
{
	if (word_len <= 8)
		return 1;
	else if (word_len <= 16)
		return 2;
	else /* word_len <= 32 */
		return 4;
}

static void omap2_mcspi_set_dma_req(const struct spi_device *spi,
		int is_read, int enable)
{
	u32 l, rw;

	l = mcspi_cached_chconf0(spi);

	if (is_read) /* 1 is read, 0 write */
		rw = OMAP2_MCSPI_CHCONF_DMAR;
	else
		rw = OMAP2_MCSPI_CHCONF_DMAW;

	if (enable)
		l |= rw;
	else
		l &= ~rw;

	mcspi_write_chconf0(spi, l);
}

static void omap2_mcspi_set_enable(const struct spi_device *spi, int enable)
{
	struct omap2_mcspi_cs *cs = spi->controller_state;
	u32 l;

	l = cs->chctrl0;
	if (enable)
		l |= OMAP2_MCSPI_CHCTRL_EN;
	else
		l &= ~OMAP2_MCSPI_CHCTRL_EN;
	cs->chctrl0 = l;
	mcspi_write_cs_reg(spi, OMAP2_MCSPI_CHCTRL0, cs->chctrl0);
	/* Flash post-writes */
	mcspi_read_cs_reg(spi, OMAP2_MCSPI_CHCTRL0);
}

static void omap2_mcspi_force_cs(struct spi_device *spi, int cs_active)
{
	u32 l;

	l = mcspi_cached_chconf0(spi);
	if (cs_active)
		l |= OMAP2_MCSPI_CHCONF_FORCE;
	else
		l &= ~OMAP2_MCSPI_CHCONF_FORCE;

	mcspi_write_chconf0(spi, l);
}

static void omap2_mcspi_set_master_mode(struct spi_master *master)
{
	struct omap2_mcspi	*mcspi = spi_master_get_devdata(master);
	struct omap2_mcspi_regs	*ctx = &mcspi->ctx;
	u32 l;

	/*
	 * Setup when switching from (reset default) slave mode
	 * to single-channel master mode
	 */
	l = mcspi_read_reg(master, OMAP2_MCSPI_MODULCTRL);
	l &= ~(OMAP2_MCSPI_MODULCTRL_STEST | OMAP2_MCSPI_MODULCTRL_MS);
	l |= OMAP2_MCSPI_MODULCTRL_SINGLE;
	mcspi_write_reg(master, OMAP2_MCSPI_MODULCTRL, l);

	ctx->modulctrl = l;
}

static void omap2_mcspi_set_fifo(const struct spi_device *spi,
				struct spi_transfer *t, int enable)
{
	struct spi_master *master = spi->master;
	struct omap2_mcspi_cs *cs = spi->controller_state;
	struct omap2_mcspi *mcspi;
	unsigned int wcnt;
	int max_fifo_depth, fifo_depth, bytes_per_word;
	u32 chconf, xferlevel;

	mcspi = spi_master_get_devdata(master);

	chconf = mcspi_cached_chconf0(spi);
	if (enable) {
		bytes_per_word = mcspi_bytes_per_word(cs->word_len);
		if (t->len % bytes_per_word != 0)
			goto disable_fifo;

		if (t->rx_buf != NULL && t->tx_buf != NULL)
			max_fifo_depth = OMAP2_MCSPI_MAX_FIFODEPTH / 2;
		else
			max_fifo_depth = OMAP2_MCSPI_MAX_FIFODEPTH;

		fifo_depth = gcd(t->len, max_fifo_depth);
		if (fifo_depth < 2 || fifo_depth % bytes_per_word != 0)
			goto disable_fifo;

		wcnt = t->len / bytes_per_word;
		if (wcnt > OMAP2_MCSPI_MAX_FIFOWCNT)
			goto disable_fifo;

		xferlevel = wcnt << 16;
		if (t->rx_buf != NULL) {
			chconf |= OMAP2_MCSPI_CHCONF_FFER;
			xferlevel |= (fifo_depth - 1) << 8;
		}
		if (t->tx_buf != NULL) {
			chconf |= OMAP2_MCSPI_CHCONF_FFET;
			xferlevel |= fifo_depth - 1;
		}

		mcspi_write_reg(master, OMAP2_MCSPI_XFERLEVEL, xferlevel);
		mcspi_write_chconf0(spi, chconf);
		mcspi->fifo_depth = fifo_depth;

		return;
	}

disable_fifo:
	if (t->rx_buf != NULL)
		chconf &= ~OMAP2_MCSPI_CHCONF_FFER;

	if (t->tx_buf != NULL)
		chconf &= ~OMAP2_MCSPI_CHCONF_FFET;

	mcspi_write_chconf0(spi, chconf);
	mcspi->fifo_depth = 0;
}

static void omap2_mcspi_restore_ctx(struct omap2_mcspi *mcspi)
{
	struct spi_master	*spi_cntrl = mcspi->master;
	struct omap2_mcspi_regs	*ctx = &mcspi->ctx;
	struct omap2_mcspi_cs	*cs;

	/* McSPI: context restore */
	mcspi_write_reg(spi_cntrl, OMAP2_MCSPI_MODULCTRL, ctx->modulctrl);
	mcspi_write_reg(spi_cntrl, OMAP2_MCSPI_WAKEUPENABLE, ctx->wakeupenable);

	list_for_each_entry(cs, &ctx->cs, node)
		writel_relaxed(cs->chconf0, cs->base + OMAP2_MCSPI_CHCONF0);
}

static int mcspi_wait_for_reg_bit(void __iomem *reg, unsigned long bit)
{
	unsigned long timeout;

	timeout = jiffies + msecs_to_jiffies(1000);
	while (!(readl_relaxed(reg) & bit)) {
		if (time_after(jiffies, timeout)) {
			if (!(readl_relaxed(reg) & bit))
				return -ETIMEDOUT;
			else
				return 0;
		}
		cpu_relax();
	}
	return 0;
}

static void omap2_mcspi_rx_callback(void *data)
{
	struct spi_device *spi = data;
	struct omap2_mcspi *mcspi = spi_master_get_devdata(spi->master);
	struct omap2_mcspi_dma *mcspi_dma = &mcspi->dma_channels[spi->chip_select];

	/* We must disable the DMA RX request */
	omap2_mcspi_set_dma_req(spi, 1, 0);

	complete(&mcspi_dma->dma_rx_completion);
}

static void omap2_mcspi_tx_callback(void *data)
{
	struct spi_device *spi = data;
	struct omap2_mcspi *mcspi = spi_master_get_devdata(spi->master);
	struct omap2_mcspi_dma *mcspi_dma = &mcspi->dma_channels[spi->chip_select];

	/* We must disable the DMA TX request */
	omap2_mcspi_set_dma_req(spi, 0, 0);

	complete(&mcspi_dma->dma_tx_completion);
}

static void omap2_mcspi_tx_dma(struct spi_device *spi,
				struct spi_transfer *xfer,
				struct dma_slave_config cfg)
{
	struct omap2_mcspi	*mcspi;
	struct omap2_mcspi_dma  *mcspi_dma;
	unsigned int		count;

	mcspi = spi_master_get_devdata(spi->master);
	mcspi_dma = &mcspi->dma_channels[spi->chip_select];
	count = xfer->len;

	if (mcspi_dma->dma_tx) {
		struct dma_async_tx_descriptor *tx;
		struct scatterlist sg;

		dmaengine_slave_config(mcspi_dma->dma_tx, &cfg);

		sg_init_table(&sg, 1);
		sg_dma_address(&sg) = xfer->tx_dma;
		sg_dma_len(&sg) = xfer->len;

		tx = dmaengine_prep_slave_sg(mcspi_dma->dma_tx, &sg, 1,
		DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
		if (tx) {
			tx->callback = omap2_mcspi_tx_callback;
			tx->callback_param = spi;
			dmaengine_submit(tx);
		} else {
			/* FIXME: fall back to PIO? */
		}
	}
	dma_async_issue_pending(mcspi_dma->dma_tx);
	omap2_mcspi_set_dma_req(spi, 0, 1);

}

static unsigned
omap2_mcspi_rx_dma(struct spi_device *spi, struct spi_transfer *xfer,
				struct dma_slave_config cfg,
				unsigned es)
{
	struct omap2_mcspi	*mcspi;
	struct omap2_mcspi_dma  *mcspi_dma;
	unsigned int		count, dma_count;
	u32			l;
	int			elements = 0;
	int			word_len, element_count;
	struct omap2_mcspi_cs	*cs = spi->controller_state;
	mcspi = spi_master_get_devdata(spi->master);
	mcspi_dma = &mcspi->dma_channels[spi->chip_select];
	count = xfer->len;
	dma_count = xfer->len;

	if (mcspi->fifo_depth == 0)
		dma_count -= es;

	word_len = cs->word_len;
	l = mcspi_cached_chconf0(spi);


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