drivers/spi/spi-img-spfi.c

/*
 * IMG SPFI controller driver
 *
 * Copyright (C) 2007,2008,2013 Imagination Technologies Ltd.
 * Copyright (C) 2014 Google, Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>
#include <linux/spinlock.h>

#define SPFI_DEVICE_PARAMETER(x)		(0x00 + 0x4 * (x))
#define SPFI_DEVICE_PARAMETER_BITCLK_SHIFT	24
#define SPFI_DEVICE_PARAMETER_BITCLK_MASK	0xff
#define SPFI_DEVICE_PARAMETER_CSSETUP_SHIFT	16
#define SPFI_DEVICE_PARAMETER_CSSETUP_MASK	0xff
#define SPFI_DEVICE_PARAMETER_CSHOLD_SHIFT	8
#define SPFI_DEVICE_PARAMETER_CSHOLD_MASK	0xff
#define SPFI_DEVICE_PARAMETER_CSDELAY_SHIFT	0
#define SPFI_DEVICE_PARAMETER_CSDELAY_MASK	0xff

#define SPFI_CONTROL				0x14
#define SPFI_CONTROL_CONTINUE			BIT(12)
#define SPFI_CONTROL_SOFT_RESET			BIT(11)
#define SPFI_CONTROL_SEND_DMA			BIT(10)
#define SPFI_CONTROL_GET_DMA			BIT(9)
#define SPFI_CONTROL_SE			BIT(8)
#define SPFI_CONTROL_TMODE_SHIFT		5
#define SPFI_CONTROL_TMODE_MASK			0x7
#define SPFI_CONTROL_TMODE_SINGLE		0
#define SPFI_CONTROL_TMODE_DUAL			1
#define SPFI_CONTROL_TMODE_QUAD			2
#define SPFI_CONTROL_SPFI_EN			BIT(0)

#define SPFI_TRANSACTION			0x18
#define SPFI_TRANSACTION_TSIZE_SHIFT		16
#define SPFI_TRANSACTION_TSIZE_MASK		0xffff

#define SPFI_PORT_STATE				0x1c
#define SPFI_PORT_STATE_DEV_SEL_SHIFT		20
#define SPFI_PORT_STATE_DEV_SEL_MASK		0x7
#define SPFI_PORT_STATE_CK_POL(x)		BIT(19 - (x))
#define SPFI_PORT_STATE_CK_PHASE(x)		BIT(14 - (x))

#define SPFI_TX_32BIT_VALID_DATA		0x20
#define SPFI_TX_8BIT_VALID_DATA			0x24
#define SPFI_RX_32BIT_VALID_DATA		0x28
#define SPFI_RX_8BIT_VALID_DATA			0x2c

#define SPFI_INTERRUPT_STATUS			0x30
#define SPFI_INTERRUPT_ENABLE			0x34
#define SPFI_INTERRUPT_CLEAR			0x38
#define SPFI_INTERRUPT_IACCESS			BIT(12)
#define SPFI_INTERRUPT_GDEX8BIT			BIT(11)
#define SPFI_INTERRUPT_ALLDONETRIG		BIT(9)
#define SPFI_INTERRUPT_GDFUL			BIT(8)
#define SPFI_INTERRUPT_GDHF			BIT(7)
#define SPFI_INTERRUPT_GDEX32BIT		BIT(6)
#define SPFI_INTERRUPT_GDTRIG			BIT(5)
#define SPFI_INTERRUPT_SDFUL			BIT(3)
#define SPFI_INTERRUPT_SDHF			BIT(2)
#define SPFI_INTERRUPT_SDE			BIT(1)
#define SPFI_INTERRUPT_SDTRIG			BIT(0)

/*
 * There are four parallel FIFOs of 16 bytes each.  The word buffer
 * (*_32BIT_VALID_DATA) accesses all four FIFOs at once, resulting in an
 * effective FIFO size of 64 bytes.  The byte buffer (*_8BIT_VALID_DATA)
 * accesses only a single FIFO, resulting in an effective FIFO size of
 * 16 bytes.
 */
#define SPFI_32BIT_FIFO_SIZE			64
#define SPFI_8BIT_FIFO_SIZE			16

struct img_spfi {
	struct device *dev;
	struct spi_master *master;
	spinlock_t lock;

	void __iomem *regs;
	phys_addr_t phys;
	int irq;
	struct clk *spfi_clk;
	struct clk *sys_clk;

	struct dma_chan *rx_ch;
	struct dma_chan *tx_ch;
	bool tx_dma_busy;
	bool rx_dma_busy;
};

struct img_spfi_device_data {
	bool gpio_requested;
};

static inline u32 spfi_readl(struct img_spfi *spfi, u32 reg)
{
	return readl(spfi->regs + reg);
}

static inline void spfi_writel(struct img_spfi *spfi, u32 val, u32 reg)
{
	writel(val, spfi->regs + reg);
}

static inline void spfi_start(struct img_spfi *spfi)
{
	u32 val;

	val = spfi_readl(spfi, SPFI_CONTROL);
	val |= SPFI_CONTROL_SPFI_EN;
	spfi_writel(spfi, val, SPFI_CONTROL);
}

static inline void spfi_reset(struct img_spfi *spfi)
{
	spfi_writel(spfi, SPFI_CONTROL_SOFT_RESET, SPFI_CONTROL);
	spfi_writel(spfi, 0, SPFI_CONTROL);
}

static int spfi_wait_all_done(struct img_spfi *spfi)
{
	unsigned long timeout = jiffies + msecs_to_jiffies(50);

	while (time_before(jiffies, timeout)) {
		u32 status = spfi_readl(spfi, SPFI_INTERRUPT_STATUS);

		if (status & SPFI_INTERRUPT_ALLDONETRIG) {
			spfi_writel(spfi, SPFI_INTERRUPT_ALLDONETRIG,
				    SPFI_INTERRUPT_CLEAR);
			return 0;
		}
		cpu_relax();
	}

	dev_err(spfi->dev, "Timed out waiting for transaction to complete\n");
	spfi_reset(spfi);

	return -ETIMEDOUT;
}

static unsigned int spfi_pio_write32(struct img_spfi *spfi, const u32 *buf,
				     unsigned int max)
{
	unsigned int count = 0;
	u32 status;

	while (count < max / 4) {
		spfi_writel(spfi, SPFI_INTERRUPT_SDFUL, SPFI_INTERRUPT_CLEAR);
		status = spfi_readl(spfi, SPFI_INTERRUPT_STATUS);
		if (status & SPFI_INTERRUPT_SDFUL)
			break;
		spfi_writel(spfi, buf[count], SPFI_TX_32BIT_VALID_DATA);
		count++;
	}

	return count * 4;
}

static unsigned int spfi_pio_write8(struct img_spfi *spfi, const u8 *buf,
				    unsigned int max)
{
	unsigned int count = 0;
	u32 status;

	while (count < max) {
		spfi_writel(spfi, SPFI_INTERRUPT_SDFUL, SPFI_INTERRUPT_CLEAR);
		status = spfi_readl(spfi, SPFI_INTERRUPT_STATUS);
		if (status & SPFI_INTERRUPT_SDFUL)
			break;
		spfi_writel(spfi, buf[count], SPFI_TX_8BIT_VALID_DATA);
		count++;
	}

	return count;
}

static unsigned int spfi_pio_read32(struct img_spfi *spfi, u32 *buf,
				    unsigned int max)
{
	unsigned int count = 0;
	u32 status;

	while (count < max / 4) {
		spfi_writel(spfi, SPFI_INTERRUPT_GDEX32BIT,
			    SPFI_INTERRUPT_CLEAR);
		status = spfi_readl(spfi, SPFI_INTERRUPT_STATUS);
		if (!(status & SPFI_INTERRUPT_GDEX32BIT))
			break;
		buf[count] = spfi_readl(spfi, SPFI_RX_32BIT_VALID_DATA);
		count++;
	}

	return count * 4;
}

static unsigned int spfi_pio_read8(struct img_spfi *spfi, u8 *buf,
				   unsigned int max)
{
	unsigned int count = 0;
	u32 status;

	while (count < max) {
		spfi_writel(spfi, SPFI_INTERRUPT_GDEX8BIT,
			    SPFI_INTERRUPT_CLEAR);
		status = spfi_readl(spfi, SPFI_INTERRUPT_STATUS);
		if (!(status & SPFI_INTERRUPT_GDEX8BIT))
			break;
		buf[count] = spfi_readl(spfi, SPFI_RX_8BIT_VALID_DATA);
		count++;
	}

	return count;
}

static int img_spfi_start_pio(struct spi_master *master,
			       struct spi_device *spi,
			       struct spi_transfer *xfer)
{
	struct img_spfi *spfi = spi_master_get_devdata(spi->master);
	unsigned int tx_bytes = 0, rx_bytes = 0;
	const void *tx_buf = xfer->tx_buf;
	void *rx_buf = xfer->rx_buf;
	unsigned long timeout;
	int ret;

	if (tx_buf)
		tx_bytes = xfer->len;
	if (rx_buf)
		rx_bytes = xfer->len;

	spfi_start(spfi);

	timeout = jiffies +
		msecs_to_jiffies(xfer->len * 8 * 1000 / xfer->speed_hz + 100);
	while ((tx_bytes > 0 || rx_bytes > 0) &&
	       time_before(jiffies, timeout)) {
		unsigned int tx_count, rx_count;

		if (tx_bytes >= 4)
			tx_count = spfi_pio_write32(spfi, tx_buf, tx_bytes);
		else
			tx_count = spfi_pio_write8(spfi, tx_buf, tx_bytes);

		if (rx_bytes >= 4)
			rx_count = spfi_pio_read32(spfi, rx_buf, rx_bytes);
		else
			rx_count = spfi_pio_read8(spfi, rx_buf, rx_bytes);

		tx_buf += tx_count;
		rx_buf += rx_count;
		tx_bytes -= tx_count;
		rx_bytes -= rx_count;

		cpu_relax();
	}

	if (rx_bytes > 0 || tx_bytes > 0) {
		dev_err(spfi->dev, "PIO transfer timed out\n");
		return -ETIMEDOUT;
	}

	ret = spfi_wait_all_done(spfi);
	if (ret < 0)
		return ret;

	return 0;
}

static void img_spfi_dma_rx_cb(void *data)
{
	struct img_spfi *spfi = data;
	unsigned long flags;

	spfi_wait_all_done(spfi);

	spin_lock_irqsave(&spfi->lock, flags);
	spfi->rx_dma_busy = false;
	if (!spfi->tx_dma_busy)
		spi_finalize_current_transfer(spfi->master);
	spin_unlock_irqrestore(&spfi->lock, flags);
}

static void img_spfi_dma_tx_cb(void *data)
{
	struct img_spfi *spfi = data;
	unsigned long flags;

	spfi_wait_all_done(spfi);

	spin_lock_irqsave(&spfi->lock, flags);
	spfi->tx_dma_busy = false;
	if (!spfi->rx_dma_busy)
		spi_finalize_current_transfer(spfi->master);
	spin_unlock_irqrestore(&spfi->lock, flags);
}

static int img_spfi_start_dma(struct spi_master *master,
			      struct spi_device *spi,
			      struct spi_transfer *xfer)
{
	struct img_spfi *spfi = spi_master_get_devdata(spi->master);
	struct dma_async_tx_descriptor *rxdesc = NULL, *txdesc = NULL;
	struct dma_slave_config rxconf, txconf;

	spfi->rx_dma_busy = false;
	spfi->tx_dma_busy = false;

	if (xfer->rx_buf) {
		rxconf.direction = DMA_DEV_TO_MEM;
		if (xfer->len % 4 == 0) {
			rxconf.src_addr = spfi->phys + SPFI_RX_32BIT_VALID_DATA;
			rxconf.src_addr_width = 4;
			rxconf.src_maxburst = 4;
		} else {
			rxconf.src_addr = spfi->phys + SPFI_RX_8BIT_VALID_DATA;
			rxconf.src_addr_width = 1;
			rxconf.src_maxburst = 4;
		}
		dmaengine_slave_config(spfi->rx_ch, &rxconf);

		rxdesc = dmaengine_prep_slave_sg(spfi->rx_ch, xfer->rx_sg.sgl,
						 xfer->rx_sg.nents,
						 DMA_DEV_TO_MEM,
						 DMA_PREP_INTERRUPT);
		if (!rxdesc)
			goto stop_dma;

		rxdesc->callback = img_spfi_dma_rx_cb;
		rxdesc->callback_param = spfi;
	}

	if (xfer->tx_buf) {
		txconf.direction = DMA_MEM_TO_DEV;
		if (xfer->len % 4 == 0) {
			txconf.dst_addr = spfi->phys + SPFI_TX_32BIT_VALID_DATA;
			txconf.dst_addr_width = 4;
			txconf.dst_maxburst = 4;
		} else {
			txconf.dst_addr = spfi->phys + SPFI_TX_8BIT_VALID_DATA;
			txconf.dst_addr_width = 1;
			txconf.dst_maxburst = 4;
		}
		dmaengine_slave_config(spfi->tx_ch, &txconf);

		txdesc = dmaengine_prep_slave_sg(spfi->tx_ch, xfer->tx_sg.sgl,
						 xfer->tx_sg.nents,
						 DMA_MEM_TO_DEV,
						 DMA_PREP_INTERRUPT);
		if (!txdesc)
			goto stop_dma;

		txdesc->callback = img_spfi_dma_tx_cb;
		txdesc->callback_param = spfi;
	}

	if (xfer->rx_buf) {
		spfi->rx_dma_busy = true;
		dmaengine_submit(rxdesc);
		dma_async_issue_pending(spfi->rx_ch);
	}

	spfi_start(spfi);

	if (xfer->tx_buf) {
		spfi->tx_dma_busy = true;
		dmaengine_submit(txdesc);
		dma_async_issue_pending(spfi->tx_ch);
	}

	return 1;

stop_dma:
	dmaengine_terminate_all(spfi->rx_ch);
	dmaengine_terminate_all(spfi->tx_ch);
	return -EIO;
}

static void img_spfi_handle_err(struct spi_master *master,
				struct spi_message *msg)
{
	struct img_spfi *spfi = spi_master_get_devdata(master);
	unsigned long flags;

	/*
	 * Stop all DMA and reset the controller if the previous transaction
	 * timed-out and never completed it's DMA.
	 */
	spin_lock_irqsave(&spfi->lock, flags);
	if (spfi->tx_dma_busy || spfi->rx_dma_busy) {
		spfi->tx_dma_busy = false;
		spfi->rx_dma_busy = false;

		dmaengine_terminate_all(spfi->tx_ch);
		dmaengine_terminate_all(spfi->rx_ch);
	}
	spin_unlock_irqrestore(&spfi->lock, flags);
}

static int img_spfi_prepare(struct spi_master *master, struct spi_message *msg)
{
	struct img_spfi *spfi = spi_master_get_devdata(master);
	u32 val;

	val = spfi_readl(spfi, SPFI_PORT_STATE);
	val &= ~(SPFI_PORT_STATE_DEV_SEL_MASK <<
		 SPFI_PORT_STATE_DEV_SEL_SHIFT);
	val |= msg->spi->chip_select << SPFI_PORT_STATE_DEV_SEL_SHIFT;
	if (msg->spi->mode & SPI_CPHA)
		val |= SPFI_PORT_STATE_CK_PHASE(msg->spi->chip_select);
	else
		val &= ~SPFI_PORT_STATE_CK_PHASE(msg->spi->chip_select);
	if (msg->spi->mode & SPI_CPOL)
		val |= SPFI_PORT_STATE_CK_POL(msg->spi->chip_select);
	else
		val &= ~SPFI_PORT_STATE_CK_POL(msg->spi->chip_select);
	spfi_writel(spfi, val, SPFI_PORT_STATE);

	return 0;
}

static int img_spfi_unprepare(struct spi_master *master,
			      struct spi_message *msg)
{
	struct img_spfi *spfi = spi_master_get_devdata(master);

	spfi_reset(spfi);

	return 0;
}

static int img_spfi_setup(struct spi_device *spi)
{
	int ret = -EINVAL;
	struct img_spfi_device_data *spfi_data = spi_get_ctldata(spi);

	if (!spfi_data) {
		spfi_data = kzalloc(sizeof(*spfi_data), GFP_KERNEL);
		if (!spfi_data)
			return -ENOMEM;
		spfi_data->gpio_requested = false;
		spi_set_ctldata(spi, spfi_data);
	}
	if (!spfi_data->gpio_requested) {
		ret = gpio_request_one(spi->cs_gpio,
				       (spi->mode & SPI_CS_HIGH) ?
				       GPIOF_OUT_INIT_LOW : GPIOF_OUT_INIT_HIGH,
				       dev_name(&spi->dev));
		if (ret)
			dev_err(&spi->dev, "can't request chipselect gpio %d\n",
				spi->cs_gpio);
		else
			spfi_data->gpio_requested = true;
	} else {
		if (gpio_is_valid(spi->cs_gpio)) {
			int mode = ((spi->mode & SPI_CS_HIGH) ?
				    GPIOF_OUT_INIT_LOW : GPIOF_OUT_INIT_HIGH);

			ret = gpio_direction_output(spi->cs_gpio, mode);
			if (ret)
				dev_err(&spi->dev, "chipselect gpio %d setup failed (%d)\n",
					spi->cs_gpio, ret);
		}
	}
	return ret;
}

static void img_spfi_cleanup(struct spi_device *spi)
{
	struct img_spfi_device_data *spfi_data = spi_get_ctldata(spi);

	if (spfi_data) {
		if (spfi_data->gpio_requested)
			gpio_free(spi->cs_gpio);
		kfree(spfi_data);
		spi_set_ctldata(spi, NULL);
	}
}

static void img_spfi_config(struct spi_master *master, struct spi_device *spi,
			    struct spi_transfer *xfer)
{
	struct img_spfi *spfi = spi_master_get_devdata(spi->master);
	u32 val, div;

	/*
	 * output = spfi_clk * (BITCLK / 512), where BITCLK must be a
	 * power of 2 up to 128
	 */
	div = DIV_ROUND_UP(clk_get_rate(spfi->spfi_clk), xfer->speed_hz);
	div = clamp(512 / (1 << get_count_order(div)), 1, 128);

	val = spfi_readl(spfi, SPFI_DEVICE_PARAMETER(spi->chip_select));
	val &= ~(SPFI_DEVICE_PARAMETER_BITCLK_MASK <<
		 SPFI_DEVICE_PARAMETER_BITCLK_SHIFT);
	val |= div << SPFI_DEVICE_PARAMETER_BITCLK_SHIFT;
	spfi_writel(spfi, val, SPFI_DEVICE_PARAMETER(spi->chip_select));

	spfi_writel(spfi, xfer->len << SPFI_TRANSACTION_TSIZE_SHIFT,
		    SPFI_TRANSACTION);

	val = spfi_readl(spfi, SPFI_CONTROL);
	val &= ~(SPFI_CONTROL_SEND_DMA | SPFI_CONTROL_GET_DMA);
	if (xfer->tx_buf)
		val |= SPFI_CONTROL_SEND_DMA;
	if (xfer->rx_buf)
		val |= SPFI_CONTROL_GET_DMA;
	val &= ~(SPFI_CONTROL_TMODE_MASK << SPFI_CONTROL_TMODE_SHIFT);
	if (xfer->tx_nbits == SPI_NBITS_DUAL &&
	    xfer->rx_nbits == SPI_NBITS_DUAL)
		val |= SPFI_CONTROL_TMODE_DUAL << SPFI_CONTROL_TMODE_SHIFT;
	else if (xfer->tx_nbits == SPI_NBITS_QUAD &&
		 xfer->rx_nbits == SPI_NBITS_QUAD)
		val |= SPFI_CONTROL_TMODE_QUAD << SPFI_CONTROL_TMODE_SHIFT;
	val |= SPFI_CONTROL_SE;
	spfi_writel(spfi, val, SPFI_CONTROL);
}

static int img_spfi_transfer_one(struct spi_master *master,
				 struct spi_device *spi,
				 struct spi_transfer *xfer)
{
	struct img_spfi *spfi = spi_master_get_devdata(spi->master);
	int ret;

	if (xfer->len > SPFI_TRANSACTION_TSIZE_MASK) {
		dev_err(spfi->dev,
			"Transfer length (%d) is greater than the max supported (%d)",
			xfer->len, SPFI_TRANSACTION_TSIZE_MASK);
		return -EINVAL;
	}

	img_spfi_config(master, spi, xfer);
	if (master->can_dma && master->can_dma(master, spi, xfer))
		ret = img_spfi_start_dma(master, spi, xfer);
	else
		ret = img_spfi_start_pio(master, spi, xfer);

	return ret;
}

static bool img_spfi_can_dma(struct spi_master *master, struct spi_device *spi,
			     struct spi_transfer *xfer)
{
	if (xfer->len > SPFI_32BIT_FIFO_SIZE)
		return true;
	return false;
}

static irqreturn_t img_spfi_irq(int irq, void *dev_id)
{
	struct img_spfi *spfi = (struct img_spfi *)dev_id;
	u32 status;

	status = spfi_readl(spfi, SPFI_INTERRUPT_STATUS);
	if (status & SPFI_INTERRUPT_IACCESS) {
		spfi_writel(spfi, SPFI_INTERRUPT_IACCESS, SPFI_INTERRUPT_CLEAR);
		dev_err(spfi->dev, "Illegal access interrupt");
		return IRQ_HANDLED;
	}

	return IRQ_NONE;
}

static int img_spfi_probe(struct platform_device *pdev)
{
	struct spi_master *master;
	struct img_spfi *spfi;
	struct resource *res;
	int ret;
	u32 max_speed_hz;

	master = spi_alloc_master(&pdev->dev, sizeof(*spfi));
	if (!master)
		return -ENOMEM;
	platform_set_drvdata(pdev, master);

	spfi = spi_master_get_devdata(master);
	spfi->dev = &pdev->dev;
	spfi->master = master;
	spin_lock_init(&spfi->lock);

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	spfi->regs = devm_ioremap_resource(spfi->dev, res);
	if (IS_ERR(spfi->regs)) {
		ret = PTR_ERR(spfi->regs);
		goto put_spi;
	}
	spfi->phys = res->start;

	spfi->irq = platform_get_irq(pdev, 0);
	if (spfi->irq < 0) {
		ret = spfi->irq;
		goto put_spi;
	}
	ret = devm_request_irq(spfi->dev, spfi->irq, img_spfi_irq,
			       IRQ_TYPE_LEVEL_HIGH, dev_name(spfi->dev), spfi);
	if (ret)
		goto put_spi;

	spfi->sys_clk = devm_clk_get(spfi->dev, "sys");
	if (IS_ERR(spfi->sys_clk)) {
		ret = PTR_ERR(spfi->sys_clk);
		goto put_spi;
	}
	spfi->spfi_clk = devm_clk_get(spfi->dev, "spfi");
	if (IS_ERR(spfi->spfi_clk)) {
		ret = PTR_ERR(spfi->spfi_clk);
		goto put_spi;
	}

	ret = clk_prepare_enable(spfi->sys_clk);
	if (ret)
		goto put_spi;
	ret = clk_prepare_enable(spfi->spfi_clk);
	if (ret)
		goto disable_pclk;

	spfi_reset(spfi);
	/*
	 * Only enable the error (IACCESS) interrupt.  In PIO mode we'll
	 * poll the status of the FIFOs.
	 */
	spfi_writel(spfi, SPFI_INTERRUPT_IACCESS, SPFI_INTERRUPT_ENABLE);

	master->auto_runtime_pm = true;
	master->bus_num = pdev->id;
	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_TX_DUAL | SPI_RX_DUAL;
	if (of_property_read_bool(spfi->dev->of_node, "img,supports-quad-mode"))
		master->mode_bits |= SPI_TX_QUAD | SPI_RX_QUAD;
	master->dev.of_node = pdev->dev.of_node;
	master->bits_per_word_mask = SPI_BPW_MASK(32) | SPI_BPW_MASK(8);
	master->max_speed_hz = clk_get_rate(spfi->spfi_clk) / 4;
	master->min_speed_hz = clk_get_rate(spfi->spfi_clk) / 512;

	/*
	 * Maximum speed supported by spfi is limited to the lower value
	 * between 1/4 of the SPFI clock or to "spfi-max-frequency"
	 * defined in the device tree.
	 * If no value is defined in the device tree assume the maximum
	 * speed supported to be 1/4 of the SPFI clock.
	 */
	if (!of_property_read_u32(spfi->dev->of_node, "spfi-max-frequency",
				  &max_speed_hz)) {
		if (master->max_speed_hz > max_speed_hz)
			master->max_speed_hz = max_speed_hz;
	}

	master->setup = img_spfi_setup;
	master->cleanup = img_spfi_cleanup;
	master->transfer_one = img_spfi_transfer_one;
	master->prepare_message = img_spfi_prepare;
	master->unprepare_message = img_spfi_unprepare;
	master->handle_err = img_spfi_handle_err;

	spfi->tx_ch = dma_request_slave_channel(spfi->dev, "tx");
	spfi->rx_ch = dma_request_slave_channel(spfi->dev, "rx");
	if (!spfi->tx_ch || !spfi->rx_ch) {
		if (spfi->tx_ch)
			dma_release_channel(spfi->tx_ch);
		if (spfi->rx_ch)
			dma_release_channel(spfi->rx_ch);
		spfi->tx_ch = NULL;
		spfi->rx_ch = NULL;
		dev_warn(spfi->dev, "Failed to get DMA channels, falling back to PIO mode\n");
	} else {
		master->dma_tx = spfi->tx_ch;
		master->dma_rx = spfi->rx_ch;
		master->can_dma = img_spfi_can_dma;
	}

	pm_runtime_set_active(spfi->dev);
	pm_runtime_enable(spfi->dev);

	ret = devm_spi_register_master(spfi->dev, master);
	if (ret)
		goto disable_pm;

	return 0;

disable_pm:
	pm_runtime_disable(spfi->dev);
	if (spfi->rx_ch)
		dma_release_channel(spfi->rx_ch);
	if (spfi->tx_ch)
		dma_release_channel(spfi->tx_ch);
	clk_disable_unprepare(spfi->spfi_clk);
disable_pclk:
	clk_disable_unprepare(spfi->sys_clk);
put_spi:
	spi_master_put(master);

	return ret;
}

static int img_spfi_remove(struct platform_device *pdev)
{
	struct spi_master *master = platform_get_drvdata(pdev);
	struct img_spfi *spfi = spi_master_get_devdata(master);

	if (spfi->tx_ch)
		dma_release_channel(spfi->tx_ch);
	if (spfi->rx_ch)
		dma_release_channel(spfi->rx_ch);

	pm_runtime_disable(spfi->dev);
	if (!pm_runtime_status_suspended(spfi->dev)) {
		clk_disable_unprepare(spfi->spfi_clk);
		clk_disable_unprepare(spfi->sys_clk);
	}

	return 0;
}

#ifdef CONFIG_PM
static int img_spfi_runtime_suspend(struct device *dev)
{
	struct spi_master *master = dev_get_drvdata(dev);
	struct img_spfi *spfi = spi_master_get_devdata(master);

	clk_disable_unprepare(spfi->spfi_clk);
	clk_disable_unprepare(spfi->sys_clk);

	return 0;
}

static int img_spfi_runtime_resume(struct device *dev)
{
	struct spi_master *master = dev_get_drvdata(dev);
	struct img_spfi *spfi = spi_master_get_devdata(master);
	int ret;

	ret = clk_prepare_enable(spfi->sys_clk);
	if (ret)
		return ret;
	ret = clk_prepare_enable(spfi->spfi_clk);
	if (ret) {
		clk_disable_unprepare(spfi->sys_clk);
		return ret;
	}

	return 0;
}
#endif /* CONFIG_PM */

#ifdef CONFIG_PM_SLEEP
static int img_spfi_suspend(struct device *dev)
{
	struct spi_master *master = dev_get_drvdata(dev);

	return spi_master_suspend(master);
}

static int img_spfi_resume(struct device *dev)
{
	struct spi_master *master = dev_get_drvdata(dev);
	struct img_spfi *spfi = spi_master_get_devdata(master);
	int ret;

	ret = pm_runtime_get_sync(dev);
	if (ret)
		return ret;
	spfi_reset(spfi);
	pm_runtime_put(dev);

	return spi_master_resume(master);
}
#endif /* CONFIG_PM_SLEEP */

static const struct dev_pm_ops img_spfi_pm_ops = {
	SET_RUNTIME_PM_OPS(img_spfi_runtime_suspend, img_spfi_runtime_resume,
			   NULL)
	SET_SYSTEM_SLEEP_PM_OPS(img_spfi_suspend, img_spfi_resume)
};

static const struct of_device_id img_spfi_of_match[] = {
	{ .compatible = "img,spfi", },
	{ },
};
MODULE_DEVICE_TABLE(of, img_spfi_of_match);

static struct platform_driver img_spfi_driver = {
	.driver = {
		.name = "img-spfi",
		.pm = &img_spfi_pm_ops,
		.of_match_table = of_match_ptr(img_spfi_of_match),
	},
	.probe = img_spfi_probe,
	.remove = img_spfi_remove,
};
module_platform_driver(img_spfi_driver);

MODULE_DESCRIPTION("IMG SPFI controller driver");
MODULE_AUTHOR("Andrew Bresticker <abrestic@chromium.org>");
MODULE_LICENSE("GPL v2");