drivers/spi/spi-dw.c - kernel/msm-4.9 - Gitiles

 /*
  * Designware SPI core controller driver (refer pxa2xx_spi.c)
  *
  * Copyright (c) 2009, Intel Corporation.
  *
  * 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.
  *
  * This program is distributed in the hope 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.
  */

 #include <linux/dma-mapping.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/highmem.h>
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/spi/spi.h>
 #include <linux/gpio.h>

 #include "spi-dw.h"

 #ifdef CONFIG_DEBUG_FS
 #include <linux/debugfs.h>
 #endif

 /* Slave spi_dev related */
 struct chip_data {
 	u8 cs;			/* chip select pin */
 	u8 tmode;		/* TR/TO/RO/EEPROM */
 	u8 type;		/* SPI/SSP/MicroWire */

 	u8 poll_mode;		/* 1 means use poll mode */

 	u8 enable_dma;
 	u16 clk_div;		/* baud rate divider */
 	u32 speed_hz;		/* baud rate */
 	void (*cs_control)(u32 command);
 };

 #ifdef CONFIG_DEBUG_FS
 #define SPI_REGS_BUFSIZE	1024
 static ssize_t dw_spi_show_regs(struct file *file, char __user *user_buf,
 		size_t count, loff_t *ppos)
 {
 	struct dw_spi *dws = file->private_data;
 	char *buf;
 	u32 len = 0;
 	ssize_t ret;

 	buf = kzalloc(SPI_REGS_BUFSIZE, GFP_KERNEL);
 	if (!buf)
 		return 0;

 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"%s registers:\n", dev_name(&dws->master->dev));
 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"=================================\n");
 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"CTRL0: \t\t0x%08x\n", dw_readl(dws, DW_SPI_CTRL0));
 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"CTRL1: \t\t0x%08x\n", dw_readl(dws, DW_SPI_CTRL1));
 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"SSIENR: \t0x%08x\n", dw_readl(dws, DW_SPI_SSIENR));
 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"SER: \t\t0x%08x\n", dw_readl(dws, DW_SPI_SER));
 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"BAUDR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_BAUDR));
 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"TXFTLR: \t0x%08x\n", dw_readl(dws, DW_SPI_TXFLTR));
 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"RXFTLR: \t0x%08x\n", dw_readl(dws, DW_SPI_RXFLTR));
 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"TXFLR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_TXFLR));
 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"RXFLR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_RXFLR));
 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"SR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_SR));
 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"IMR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_IMR));
 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"ISR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_ISR));
 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"DMACR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_DMACR));
 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"DMATDLR: \t0x%08x\n", dw_readl(dws, DW_SPI_DMATDLR));
 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"DMARDLR: \t0x%08x\n", dw_readl(dws, DW_SPI_DMARDLR));
 	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
 			"=================================\n");

 	ret = simple_read_from_buffer(user_buf, count, ppos, buf, len);
 	kfree(buf);
 	return ret;
 }

 static const struct file_operations dw_spi_regs_ops = {
 	.owner		= THIS_MODULE,
 	.open		= simple_open,
 	.read		= dw_spi_show_regs,
 	.llseek		= default_llseek,
 };

 static int dw_spi_debugfs_init(struct dw_spi *dws)
 {
 	char name[128];

 	snprintf(name, 128, "dw_spi-%s", dev_name(&dws->master->dev));
 	dws->debugfs = debugfs_create_dir(name, NULL);
 	if (!dws->debugfs)
 		return -ENOMEM;

 	debugfs_create_file("registers", S_IFREG | S_IRUGO,
 		dws->debugfs, (void *)dws, &dw_spi_regs_ops);
 	return 0;
 }

 static void dw_spi_debugfs_remove(struct dw_spi *dws)
 {
 	debugfs_remove_recursive(dws->debugfs);
 }

 #else
 static inline int dw_spi_debugfs_init(struct dw_spi *dws)
 {
 	return 0;
 }

 static inline void dw_spi_debugfs_remove(struct dw_spi *dws)
 {
 }
 #endif /* CONFIG_DEBUG_FS */

 static void dw_spi_set_cs(struct spi_device *spi, bool enable)
 {
 	struct dw_spi *dws = spi_master_get_devdata(spi->master);
 	struct chip_data *chip = spi_get_ctldata(spi);

 	/* Chip select logic is inverted from spi_set_cs() */
 	if (chip && chip->cs_control)
 		chip->cs_control(!enable);

 	if (!enable)
 		dw_writel(dws, DW_SPI_SER, BIT(spi->chip_select));
 }

 /* Return the max entries we can fill into tx fifo */
 static inline u32 tx_max(struct dw_spi *dws)
 {
 	u32 tx_left, tx_room, rxtx_gap;

 	tx_left = (dws->tx_end - dws->tx) / dws->n_bytes;
 	tx_room = dws->fifo_len - dw_readl(dws, DW_SPI_TXFLR);

 	/*
 	 * Another concern is about the tx/rx mismatch, we
 	 * though to use (dws->fifo_len - rxflr - txflr) as
 	 * one maximum value for tx, but it doesn't cover the
 	 * data which is out of tx/rx fifo and inside the
 	 * shift registers. So a control from sw point of
 	 * view is taken.
 	 */
 	rxtx_gap =  ((dws->rx_end - dws->rx) - (dws->tx_end - dws->tx))
 			/ dws->n_bytes;

 	return min3(tx_left, tx_room, (u32) (dws->fifo_len - rxtx_gap));
 }

 /* Return the max entries we should read out of rx fifo */
 static inline u32 rx_max(struct dw_spi *dws)
 {
 	u32 rx_left = (dws->rx_end - dws->rx) / dws->n_bytes;

 	return min_t(u32, rx_left, dw_readl(dws, DW_SPI_RXFLR));
 }

 static void dw_writer(struct dw_spi *dws)
 {
 	u32 max;
 	u16 txw = 0;

 	spin_lock(&dws->buf_lock);
 	max = tx_max(dws);
 	while (max--) {
 		/* Set the tx word if the transfer's original "tx" is not null */
 		if (dws->tx_end - dws->len) {
 			if (dws->n_bytes == 1)
 				txw = *(u8 *)(dws->tx);
 			else
 				txw = *(u16 *)(dws->tx);
 		}
 		dw_write_io_reg(dws, DW_SPI_DR, txw);
 		dws->tx += dws->n_bytes;
 	}
 	spin_unlock(&dws->buf_lock);
 }

 static void dw_reader(struct dw_spi *dws)
 {
 	u32 max;
 	u16 rxw;

 	spin_lock(&dws->buf_lock);
 	max = rx_max(dws);
 	while (max--) {
 		rxw = dw_read_io_reg(dws, DW_SPI_DR);
 		/* Care rx only if the transfer's original "rx" is not null */
 		if (dws->rx_end - dws->len) {
 			if (dws->n_bytes == 1)
 				*(u8 *)(dws->rx) = rxw;
 			else
 				*(u16 *)(dws->rx) = rxw;
 		}
 		dws->rx += dws->n_bytes;
 	}
 	spin_unlock(&dws->buf_lock);
 }

 static void int_error_stop(struct dw_spi *dws, const char *msg)
 {
 	spi_reset_chip(dws);

 	dev_err(&dws->master->dev, "%s\n", msg);
 	dws->master->cur_msg->status = -EIO;
 	spi_finalize_current_transfer(dws->master);
 }

 static irqreturn_t interrupt_transfer(struct dw_spi *dws)
 {
 	u16 irq_status = dw_readl(dws, DW_SPI_ISR);

 	/* Error handling */
 	if (irq_status & (SPI_INT_TXOI | SPI_INT_RXOI | SPI_INT_RXUI)) {
 		dw_readl(dws, DW_SPI_ICR);
 		int_error_stop(dws, "interrupt_transfer: fifo overrun/underrun");
 		return IRQ_HANDLED;
 	}

 	dw_reader(dws);
 	if (dws->rx_end == dws->rx) {
 		spi_mask_intr(dws, SPI_INT_TXEI);
 		spi_finalize_current_transfer(dws->master);
 		return IRQ_HANDLED;
 	}
 	if (irq_status & SPI_INT_TXEI) {
 		spi_mask_intr(dws, SPI_INT_TXEI);
 		dw_writer(dws);
 		/* Enable TX irq always, it will be disabled when RX finished */
 		spi_umask_intr(dws, SPI_INT_TXEI);
 	}

 	return IRQ_HANDLED;
 }

 static irqreturn_t dw_spi_irq(int irq, void *dev_id)
 {
 	struct spi_master *master = dev_id;
 	struct dw_spi *dws = spi_master_get_devdata(master);
 	u16 irq_status = dw_readl(dws, DW_SPI_ISR) & 0x3f;

 	if (!irq_status)
 		return IRQ_NONE;

 	if (!master->cur_msg) {
 		spi_mask_intr(dws, SPI_INT_TXEI);
 		return IRQ_HANDLED;
 	}

 	return dws->transfer_handler(dws);
 }

 /* Must be called inside pump_transfers() */
 static int poll_transfer(struct dw_spi *dws)
 {
 	do {
 		dw_writer(dws);
 		dw_reader(dws);
 		cpu_relax();
 	} while (dws->rx_end > dws->rx);

 	return 0;
 }

 static int dw_spi_transfer_one(struct spi_master *master,
 		struct spi_device *spi, struct spi_transfer *transfer)
 {
 	struct dw_spi *dws = spi_master_get_devdata(master);
 	struct chip_data *chip = spi_get_ctldata(spi);
 	unsigned long flags;
 	u8 imask = 0;
 	u16 txlevel = 0;
 	u32 cr0;
 	int ret;

 	dws->dma_mapped = 0;
 	spin_lock_irqsave(&dws->buf_lock, flags);
 	dws->tx = (void *)transfer->tx_buf;
 	dws->tx_end = dws->tx + transfer->len;
 	dws->rx = transfer->rx_buf;
 	dws->rx_end = dws->rx + transfer->len;
 	dws->len = transfer->len;
 	spin_unlock_irqrestore(&dws->buf_lock, flags);

 	/* Ensure dw->rx and dw->rx_end are visible */
 	smp_mb();

 	spi_enable_chip(dws, 0);

 	/* Handle per transfer options for bpw and speed */
 	if (transfer->speed_hz != dws->current_freq) {
 		if (transfer->speed_hz != chip->speed_hz) {
 			/* clk_div doesn't support odd number */
 			chip->clk_div = (DIV_ROUND_UP(dws->max_freq, transfer->speed_hz) + 1) & 0xfffe;
 			chip->speed_hz = transfer->speed_hz;
 		}
 		dws->current_freq = transfer->speed_hz;
 		spi_set_clk(dws, chip->clk_div);
 	}
 	if (transfer->bits_per_word == 8) {
 		dws->n_bytes = 1;
 		dws->dma_width = 1;
 	} else if (transfer->bits_per_word == 16) {
 		dws->n_bytes = 2;
 		dws->dma_width = 2;
 	} else {
 		return -EINVAL;
 	}
 	/* Default SPI mode is SCPOL = 0, SCPH = 0 */
 	cr0 = (transfer->bits_per_word - 1)
 		| (chip->type << SPI_FRF_OFFSET)
 		| (spi->mode << SPI_MODE_OFFSET)
 		| (chip->tmode << SPI_TMOD_OFFSET);

 	/*
 	 * Adjust transfer mode if necessary. Requires platform dependent
 	 * chipselect mechanism.
 	 */
 	if (chip->cs_control) {
 		if (dws->rx && dws->tx)
 			chip->tmode = SPI_TMOD_TR;
 		else if (dws->rx)
 			chip->tmode = SPI_TMOD_RO;
 		else
 			chip->tmode = SPI_TMOD_TO;

 		cr0 &= ~SPI_TMOD_MASK;
 		cr0 |= (chip->tmode << SPI_TMOD_OFFSET);
 	}

 	dw_writel(dws, DW_SPI_CTRL0, cr0);

 	/* Check if current transfer is a DMA transaction */
 	if (master->can_dma && master->can_dma(master, spi, transfer))
 		dws->dma_mapped = master->cur_msg_mapped;

 	/* For poll mode just disable all interrupts */
 	spi_mask_intr(dws, 0xff);

 	/*
 	 * Interrupt mode
 	 * we only need set the TXEI IRQ, as TX/RX always happen syncronizely
 	 */
 	if (dws->dma_mapped) {
 		ret = dws->dma_ops->dma_setup(dws, transfer);
 		if (ret < 0) {
 			spi_enable_chip(dws, 1);
 			return ret;
 		}
 	} else if (!chip->poll_mode) {
 		txlevel = min_t(u16, dws->fifo_len / 2, dws->len / dws->n_bytes);
 		dw_writel(dws, DW_SPI_TXFLTR, txlevel);

 		/* Set the interrupt mask */
 		imask |= SPI_INT_TXEI | SPI_INT_TXOI |
 			 SPI_INT_RXUI | SPI_INT_RXOI;
 		spi_umask_intr(dws, imask);

 		dws->transfer_handler = interrupt_transfer;
 	}

 	spi_enable_chip(dws, 1);

 	if (dws->dma_mapped) {
 		ret = dws->dma_ops->dma_transfer(dws, transfer);
 		if (ret < 0)
 			return ret;
 	}

 	if (chip->poll_mode)
 		return poll_transfer(dws);

 	return 1;
 }

 static void dw_spi_handle_err(struct spi_master *master,
 		struct spi_message *msg)
 {
 	struct dw_spi *dws = spi_master_get_devdata(master);

 	if (dws->dma_mapped)
 		dws->dma_ops->dma_stop(dws);

 	spi_reset_chip(dws);
 }

 /* This may be called twice for each spi dev */
 static int dw_spi_setup(struct spi_device *spi)
 {
 	struct dw_spi_chip *chip_info = NULL;
 	struct chip_data *chip;
 	int ret;

 	/* Only alloc on first setup */
 	chip = spi_get_ctldata(spi);
 	if (!chip) {
 		chip = kzalloc(sizeof(struct chip_data), GFP_KERNEL);
 		if (!chip)
 			return -ENOMEM;
 		spi_set_ctldata(spi, chip);
 	}

 	/*
 	 * Protocol drivers may change the chip settings, so...
 	 * if chip_info exists, use it
 	 */
 	chip_info = spi->controller_data;

 	/* chip_info doesn't always exist */
 	if (chip_info) {
 		if (chip_info->cs_control)
 			chip->cs_control = chip_info->cs_control;

 		chip->poll_mode = chip_info->poll_mode;
 		chip->type = chip_info->type;
 	}

 	chip->tmode = SPI_TMOD_TR;

 	if (gpio_is_valid(spi->cs_gpio)) {
 		ret = gpio_direction_output(spi->cs_gpio,
 				!(spi->mode & SPI_CS_HIGH));
 		if (ret)
 			return ret;
 	}

 	return 0;
 }

 static void dw_spi_cleanup(struct spi_device *spi)
 {
 	struct chip_data *chip = spi_get_ctldata(spi);

 	kfree(chip);
 	spi_set_ctldata(spi, NULL);
 }

 /* Restart the controller, disable all interrupts, clean rx fifo */
 static void spi_hw_init(struct device *dev, struct dw_spi *dws)
 {
 	spi_reset_chip(dws);

 	/*
 	 * Try to detect the FIFO depth if not set by interface driver,
 	 * the depth could be from 2 to 256 from HW spec
 	 */
 	if (!dws->fifo_len) {
 		u32 fifo;

 		for (fifo = 1; fifo < 256; fifo++) {
 			dw_writel(dws, DW_SPI_TXFLTR, fifo);
 			if (fifo != dw_readl(dws, DW_SPI_TXFLTR))
 				break;
 		}
 		dw_writel(dws, DW_SPI_TXFLTR, 0);

 		dws->fifo_len = (fifo == 1) ? 0 : fifo;
 		dev_dbg(dev, "Detected FIFO size: %u bytes\n", dws->fifo_len);
 	}
 }

 int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
 {
 	struct spi_master *master;
 	int ret;

 	BUG_ON(dws == NULL);

 	master = spi_alloc_master(dev, 0);
 	if (!master)
 		return -ENOMEM;

 	dws->master = master;
 	dws->type = SSI_MOTO_SPI;
 	dws->dma_inited = 0;
 	dws->dma_addr = (dma_addr_t)(dws->paddr + DW_SPI_DR);
 	snprintf(dws->name, sizeof(dws->name), "dw_spi%d", dws->bus_num);
 	spin_lock_init(&dws->buf_lock);

 	ret = request_irq(dws->irq, dw_spi_irq, IRQF_SHARED, dws->name, master);
 	if (ret < 0) {
 		dev_err(dev, "can not get IRQ\n");
 		goto err_free_master;
 	}

 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP;
 	master->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16);
 	master->bus_num = dws->bus_num;
 	master->num_chipselect = dws->num_cs;
 	master->setup = dw_spi_setup;
 	master->cleanup = dw_spi_cleanup;
 	master->set_cs = dw_spi_set_cs;
 	master->transfer_one = dw_spi_transfer_one;
 	master->handle_err = dw_spi_handle_err;
 	master->max_speed_hz = dws->max_freq;
 	master->dev.of_node = dev->of_node;

 	/* Basic HW init */
 	spi_hw_init(dev, dws);

 	if (dws->dma_ops && dws->dma_ops->dma_init) {
 		ret = dws->dma_ops->dma_init(dws);
 		if (ret) {
 			dev_warn(dev, "DMA init failed\n");
 			dws->dma_inited = 0;
 		} else {
 			master->can_dma = dws->dma_ops->can_dma;
 		}
 	}

 	spi_master_set_devdata(master, dws);
 	ret = devm_spi_register_master(dev, master);
 	if (ret) {
 		dev_err(&master->dev, "problem registering spi master\n");
 		goto err_dma_exit;
 	}

 	dw_spi_debugfs_init(dws);
 	return 0;

 err_dma_exit:
 	if (dws->dma_ops && dws->dma_ops->dma_exit)
 		dws->dma_ops->dma_exit(dws);
 	spi_enable_chip(dws, 0);
 	free_irq(dws->irq, master);
 err_free_master:
 	spi_master_put(master);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(dw_spi_add_host);

 void dw_spi_remove_host(struct dw_spi *dws)
 {
 	dw_spi_debugfs_remove(dws);

 	if (dws->dma_ops && dws->dma_ops->dma_exit)
 		dws->dma_ops->dma_exit(dws);

 	spi_shutdown_chip(dws);

 	free_irq(dws->irq, dws->master);
 }
 EXPORT_SYMBOL_GPL(dw_spi_remove_host);

 int dw_spi_suspend_host(struct dw_spi *dws)
 {
 	int ret;

 	ret = spi_master_suspend(dws->master);
 	if (ret)
 		return ret;

 	spi_shutdown_chip(dws);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(dw_spi_suspend_host);

 int dw_spi_resume_host(struct dw_spi *dws)
 {
 	int ret;

 	spi_hw_init(&dws->master->dev, dws);
 	ret = spi_master_resume(dws->master);
 	if (ret)
 		dev_err(&dws->master->dev, "fail to start queue (%d)\n", ret);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(dw_spi_resume_host);

 MODULE_AUTHOR("Feng Tang <feng.tang@intel.com>");
 MODULE_DESCRIPTION("Driver for DesignWare SPI controller core");
 MODULE_LICENSE("GPL v2");
	/*
	* Designware SPI core controller driver (refer pxa2xx_spi.c)
	*
	* Copyright (c) 2009, Intel Corporation.
	*
	* 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.
	*
	* This program is distributed in the hope 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.
	*/

	#include <linux/dma-mapping.h>
	#include <linux/interrupt.h>
	#include <linux/module.h>
	#include <linux/highmem.h>
	#include <linux/delay.h>
	#include <linux/slab.h>
	#include <linux/spi/spi.h>
	#include <linux/gpio.h>

	#include "spi-dw.h"

	#ifdef CONFIG_DEBUG_FS
	#include <linux/debugfs.h>
	#endif

	/* Slave spi_dev related */
	struct chip_data {
	u8 cs; /* chip select pin */
	u8 tmode; /* TR/TO/RO/EEPROM */
	u8 type; /* SPI/SSP/MicroWire */

	u8 poll_mode; /* 1 means use poll mode */

	u8 enable_dma;
	u16 clk_div; /* baud rate divider */
	u32 speed_hz; /* baud rate */
	void (*cs_control)(u32 command);
	};

	#ifdef CONFIG_DEBUG_FS
	#define SPI_REGS_BUFSIZE 1024
	static ssize_t dw_spi_show_regs(struct file file, char __user user_buf,
	size_t count, loff_t *ppos)
	{
	struct dw_spi *dws = file->private_data;
	char *buf;
	u32 len = 0;
	ssize_t ret;

	buf = kzalloc(SPI_REGS_BUFSIZE, GFP_KERNEL);
	if (!buf)
	return 0;

	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"%s registers:\n", dev_name(&dws->master->dev));
	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"=================================\n");
	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"CTRL0: \t\t0x%08x\n", dw_readl(dws, DW_SPI_CTRL0));
	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"CTRL1: \t\t0x%08x\n", dw_readl(dws, DW_SPI_CTRL1));
	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"SSIENR: \t0x%08x\n", dw_readl(dws, DW_SPI_SSIENR));
	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"SER: \t\t0x%08x\n", dw_readl(dws, DW_SPI_SER));
	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"BAUDR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_BAUDR));
	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"TXFTLR: \t0x%08x\n", dw_readl(dws, DW_SPI_TXFLTR));
	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"RXFTLR: \t0x%08x\n", dw_readl(dws, DW_SPI_RXFLTR));
	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"TXFLR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_TXFLR));
	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"RXFLR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_RXFLR));
	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"SR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_SR));
	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"IMR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_IMR));
	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"ISR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_ISR));
	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"DMACR: \t\t0x%08x\n", dw_readl(dws, DW_SPI_DMACR));
	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"DMATDLR: \t0x%08x\n", dw_readl(dws, DW_SPI_DMATDLR));
	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"DMARDLR: \t0x%08x\n", dw_readl(dws, DW_SPI_DMARDLR));
	len += snprintf(buf + len, SPI_REGS_BUFSIZE - len,
	"=================================\n");

	ret = simple_read_from_buffer(user_buf, count, ppos, buf, len);
	kfree(buf);
	return ret;
	}

	static const struct file_operations dw_spi_regs_ops = {
	.owner = THIS_MODULE,
	.open = simple_open,
	.read = dw_spi_show_regs,
	.llseek = default_llseek,
	};

	static int dw_spi_debugfs_init(struct dw_spi *dws)
	{
	char name[128];

	snprintf(name, 128, "dw_spi-%s", dev_name(&dws->master->dev));
	dws->debugfs = debugfs_create_dir(name, NULL);
	if (!dws->debugfs)
	return -ENOMEM;

	debugfs_create_file("registers", S_IFREG \| S_IRUGO,
	dws->debugfs, (void *)dws, &dw_spi_regs_ops);
	return 0;
	}

	static void dw_spi_debugfs_remove(struct dw_spi *dws)
	{
	debugfs_remove_recursive(dws->debugfs);
	}

	#else
	static inline int dw_spi_debugfs_init(struct dw_spi *dws)
	{
	return 0;
	}

	static inline void dw_spi_debugfs_remove(struct dw_spi *dws)
	{
	}
	#endif /* CONFIG_DEBUG_FS */

	static void dw_spi_set_cs(struct spi_device *spi, bool enable)
	{
	struct dw_spi *dws = spi_master_get_devdata(spi->master);
	struct chip_data *chip = spi_get_ctldata(spi);

	/* Chip select logic is inverted from spi_set_cs() */
	if (chip && chip->cs_control)
	chip->cs_control(!enable);

	if (!enable)
	dw_writel(dws, DW_SPI_SER, BIT(spi->chip_select));
	}

	/* Return the max entries we can fill into tx fifo */
	static inline u32 tx_max(struct dw_spi *dws)
	{
	u32 tx_left, tx_room, rxtx_gap;

	tx_left = (dws->tx_end - dws->tx) / dws->n_bytes;
	tx_room = dws->fifo_len - dw_readl(dws, DW_SPI_TXFLR);

	/*
	* Another concern is about the tx/rx mismatch, we
	* though to use (dws->fifo_len - rxflr - txflr) as
	* one maximum value for tx, but it doesn't cover the
	* data which is out of tx/rx fifo and inside the
	* shift registers. So a control from sw point of
	* view is taken.
	*/
	rxtx_gap = ((dws->rx_end - dws->rx) - (dws->tx_end - dws->tx))
	/ dws->n_bytes;

	return min3(tx_left, tx_room, (u32) (dws->fifo_len - rxtx_gap));
	}

	/* Return the max entries we should read out of rx fifo */
	static inline u32 rx_max(struct dw_spi *dws)
	{
	u32 rx_left = (dws->rx_end - dws->rx) / dws->n_bytes;

	return min_t(u32, rx_left, dw_readl(dws, DW_SPI_RXFLR));
	}

	static void dw_writer(struct dw_spi *dws)
	{
	u32 max;
	u16 txw = 0;

	spin_lock(&dws->buf_lock);
	max = tx_max(dws);
	while (max--) {
	/* Set the tx word if the transfer's original "tx" is not null */
	if (dws->tx_end - dws->len) {
	if (dws->n_bytes == 1)
	txw = (u8 )(dws->tx);
	else
	txw = (u16 )(dws->tx);
	}
	dw_write_io_reg(dws, DW_SPI_DR, txw);
	dws->tx += dws->n_bytes;
	}
	spin_unlock(&dws->buf_lock);
	}

	static void dw_reader(struct dw_spi *dws)
	{
	u32 max;
	u16 rxw;

	spin_lock(&dws->buf_lock);
	max = rx_max(dws);
	while (max--) {
	rxw = dw_read_io_reg(dws, DW_SPI_DR);
	/* Care rx only if the transfer's original "rx" is not null */
	if (dws->rx_end - dws->len) {
	if (dws->n_bytes == 1)
	(u8 )(dws->rx) = rxw;
	else
	(u16 )(dws->rx) = rxw;
	}
	dws->rx += dws->n_bytes;
	}
	spin_unlock(&dws->buf_lock);
	}

	static void int_error_stop(struct dw_spi dws, const char msg)
	{
	spi_reset_chip(dws);

	dev_err(&dws->master->dev, "%s\n", msg);
	dws->master->cur_msg->status = -EIO;
	spi_finalize_current_transfer(dws->master);
	}

	static irqreturn_t interrupt_transfer(struct dw_spi *dws)
	{
	u16 irq_status = dw_readl(dws, DW_SPI_ISR);

	/* Error handling */
	if (irq_status & (SPI_INT_TXOI \| SPI_INT_RXOI \| SPI_INT_RXUI)) {
	dw_readl(dws, DW_SPI_ICR);
	int_error_stop(dws, "interrupt_transfer: fifo overrun/underrun");
	return IRQ_HANDLED;
	}

	dw_reader(dws);
	if (dws->rx_end == dws->rx) {
	spi_mask_intr(dws, SPI_INT_TXEI);
	spi_finalize_current_transfer(dws->master);
	return IRQ_HANDLED;
	}
	if (irq_status & SPI_INT_TXEI) {
	spi_mask_intr(dws, SPI_INT_TXEI);
	dw_writer(dws);
	/* Enable TX irq always, it will be disabled when RX finished */
	spi_umask_intr(dws, SPI_INT_TXEI);
	}

	return IRQ_HANDLED;
	}

	static irqreturn_t dw_spi_irq(int irq, void *dev_id)
	{
	struct spi_master *master = dev_id;
	struct dw_spi *dws = spi_master_get_devdata(master);
	u16 irq_status = dw_readl(dws, DW_SPI_ISR) & 0x3f;

	if (!irq_status)
	return IRQ_NONE;

	if (!master->cur_msg) {
	spi_mask_intr(dws, SPI_INT_TXEI);
	return IRQ_HANDLED;
	}

	return dws->transfer_handler(dws);
	}

	/* Must be called inside pump_transfers() */
	static int poll_transfer(struct dw_spi *dws)
	{
	do {
	dw_writer(dws);
	dw_reader(dws);
	cpu_relax();
	} while (dws->rx_end > dws->rx);

	return 0;
	}

	static int dw_spi_transfer_one(struct spi_master *master,
	struct spi_device spi, struct spi_transfer transfer)
	{
	struct dw_spi *dws = spi_master_get_devdata(master);
	struct chip_data *chip = spi_get_ctldata(spi);
	unsigned long flags;
	u8 imask = 0;
	u16 txlevel = 0;
	u32 cr0;
	int ret;

	dws->dma_mapped = 0;
	spin_lock_irqsave(&dws->buf_lock, flags);
	dws->tx = (void *)transfer->tx_buf;
	dws->tx_end = dws->tx + transfer->len;
	dws->rx = transfer->rx_buf;
	dws->rx_end = dws->rx + transfer->len;
	dws->len = transfer->len;
	spin_unlock_irqrestore(&dws->buf_lock, flags);

	/* Ensure dw->rx and dw->rx_end are visible */
	smp_mb();

	spi_enable_chip(dws, 0);

	/* Handle per transfer options for bpw and speed */
	if (transfer->speed_hz != dws->current_freq) {
	if (transfer->speed_hz != chip->speed_hz) {
	/* clk_div doesn't support odd number */
	chip->clk_div = (DIV_ROUND_UP(dws->max_freq, transfer->speed_hz) + 1) & 0xfffe;
	chip->speed_hz = transfer->speed_hz;
	}
	dws->current_freq = transfer->speed_hz;
	spi_set_clk(dws, chip->clk_div);
	}
	if (transfer->bits_per_word == 8) {
	dws->n_bytes = 1;
	dws->dma_width = 1;
	} else if (transfer->bits_per_word == 16) {
	dws->n_bytes = 2;
	dws->dma_width = 2;
	} else {
	return -EINVAL;
	}
	/* Default SPI mode is SCPOL = 0, SCPH = 0 */
	cr0 = (transfer->bits_per_word - 1)
	\| (chip->type << SPI_FRF_OFFSET)
	\| (spi->mode << SPI_MODE_OFFSET)
	\| (chip->tmode << SPI_TMOD_OFFSET);

	/*
	* Adjust transfer mode if necessary. Requires platform dependent
	* chipselect mechanism.
	*/
	if (chip->cs_control) {
	if (dws->rx && dws->tx)
	chip->tmode = SPI_TMOD_TR;
	else if (dws->rx)
	chip->tmode = SPI_TMOD_RO;
	else
	chip->tmode = SPI_TMOD_TO;

	cr0 &= ~SPI_TMOD_MASK;
	cr0 \|= (chip->tmode << SPI_TMOD_OFFSET);
	}

	dw_writel(dws, DW_SPI_CTRL0, cr0);

	/* Check if current transfer is a DMA transaction */
	if (master->can_dma && master->can_dma(master, spi, transfer))
	dws->dma_mapped = master->cur_msg_mapped;

	/* For poll mode just disable all interrupts */
	spi_mask_intr(dws, 0xff);

	/*
	* Interrupt mode
	* we only need set the TXEI IRQ, as TX/RX always happen syncronizely
	*/
	if (dws->dma_mapped) {
	ret = dws->dma_ops->dma_setup(dws, transfer);
	if (ret < 0) {
	spi_enable_chip(dws, 1);
	return ret;
	}
	} else if (!chip->poll_mode) {
	txlevel = min_t(u16, dws->fifo_len / 2, dws->len / dws->n_bytes);
	dw_writel(dws, DW_SPI_TXFLTR, txlevel);

	/* Set the interrupt mask */
	imask \|= SPI_INT_TXEI \| SPI_INT_TXOI \|
	SPI_INT_RXUI \| SPI_INT_RXOI;
	spi_umask_intr(dws, imask);

	dws->transfer_handler = interrupt_transfer;
	}

	spi_enable_chip(dws, 1);

	if (dws->dma_mapped) {
	ret = dws->dma_ops->dma_transfer(dws, transfer);
	if (ret < 0)
	return ret;
	}

	if (chip->poll_mode)
	return poll_transfer(dws);

	return 1;
	}

	static void dw_spi_handle_err(struct spi_master *master,
	struct spi_message *msg)
	{
	struct dw_spi *dws = spi_master_get_devdata(master);

	if (dws->dma_mapped)
	dws->dma_ops->dma_stop(dws);

	spi_reset_chip(dws);
	}

	/* This may be called twice for each spi dev */
	static int dw_spi_setup(struct spi_device *spi)
	{
	struct dw_spi_chip *chip_info = NULL;
	struct chip_data *chip;
	int ret;

	/* Only alloc on first setup */
	chip = spi_get_ctldata(spi);
	if (!chip) {
	chip = kzalloc(sizeof(struct chip_data), GFP_KERNEL);
	if (!chip)
	return -ENOMEM;
	spi_set_ctldata(spi, chip);
	}

	/*
	* Protocol drivers may change the chip settings, so...
	* if chip_info exists, use it
	*/
	chip_info = spi->controller_data;

	/* chip_info doesn't always exist */
	if (chip_info) {
	if (chip_info->cs_control)
	chip->cs_control = chip_info->cs_control;

	chip->poll_mode = chip_info->poll_mode;
	chip->type = chip_info->type;
	}

	chip->tmode = SPI_TMOD_TR;

	if (gpio_is_valid(spi->cs_gpio)) {
	ret = gpio_direction_output(spi->cs_gpio,
	!(spi->mode & SPI_CS_HIGH));
	if (ret)
	return ret;
	}

	return 0;
	}

	static void dw_spi_cleanup(struct spi_device *spi)
	{
	struct chip_data *chip = spi_get_ctldata(spi);

	kfree(chip);
	spi_set_ctldata(spi, NULL);
	}

	/* Restart the controller, disable all interrupts, clean rx fifo */
	static void spi_hw_init(struct device dev, struct dw_spi dws)
	{
	spi_reset_chip(dws);

	/*
	* Try to detect the FIFO depth if not set by interface driver,
	* the depth could be from 2 to 256 from HW spec
	*/
	if (!dws->fifo_len) {
	u32 fifo;

	for (fifo = 1; fifo < 256; fifo++) {
	dw_writel(dws, DW_SPI_TXFLTR, fifo);
	if (fifo != dw_readl(dws, DW_SPI_TXFLTR))
	break;
	}
	dw_writel(dws, DW_SPI_TXFLTR, 0);

	dws->fifo_len = (fifo == 1) ? 0 : fifo;
	dev_dbg(dev, "Detected FIFO size: %u bytes\n", dws->fifo_len);
	}
	}

	int dw_spi_add_host(struct device dev, struct dw_spi dws)
	{
	struct spi_master *master;
	int ret;

	BUG_ON(dws == NULL);

	master = spi_alloc_master(dev, 0);
	if (!master)
	return -ENOMEM;

	dws->master = master;
	dws->type = SSI_MOTO_SPI;
	dws->dma_inited = 0;
	dws->dma_addr = (dma_addr_t)(dws->paddr + DW_SPI_DR);
	snprintf(dws->name, sizeof(dws->name), "dw_spi%d", dws->bus_num);
	spin_lock_init(&dws->buf_lock);

	ret = request_irq(dws->irq, dw_spi_irq, IRQF_SHARED, dws->name, master);
	if (ret < 0) {
	dev_err(dev, "can not get IRQ\n");
	goto err_free_master;
	}

	master->mode_bits = SPI_CPOL \| SPI_CPHA \| SPI_LOOP;
	master->bits_per_word_mask = SPI_BPW_MASK(8) \| SPI_BPW_MASK(16);
	master->bus_num = dws->bus_num;
	master->num_chipselect = dws->num_cs;
	master->setup = dw_spi_setup;
	master->cleanup = dw_spi_cleanup;
	master->set_cs = dw_spi_set_cs;
	master->transfer_one = dw_spi_transfer_one;
	master->handle_err = dw_spi_handle_err;
	master->max_speed_hz = dws->max_freq;
	master->dev.of_node = dev->of_node;

	/* Basic HW init */
	spi_hw_init(dev, dws);

	if (dws->dma_ops && dws->dma_ops->dma_init) {
	ret = dws->dma_ops->dma_init(dws);
	if (ret) {
	dev_warn(dev, "DMA init failed\n");
	dws->dma_inited = 0;
	} else {
	master->can_dma = dws->dma_ops->can_dma;
	}
	}

	spi_master_set_devdata(master, dws);
	ret = devm_spi_register_master(dev, master);
	if (ret) {
	dev_err(&master->dev, "problem registering spi master\n");
	goto err_dma_exit;
	}

	dw_spi_debugfs_init(dws);
	return 0;

	err_dma_exit:
	if (dws->dma_ops && dws->dma_ops->dma_exit)
	dws->dma_ops->dma_exit(dws);
	spi_enable_chip(dws, 0);
	free_irq(dws->irq, master);
	err_free_master:
	spi_master_put(master);
	return ret;
	}
	EXPORT_SYMBOL_GPL(dw_spi_add_host);

	void dw_spi_remove_host(struct dw_spi *dws)
	{
	dw_spi_debugfs_remove(dws);

	if (dws->dma_ops && dws->dma_ops->dma_exit)
	dws->dma_ops->dma_exit(dws);

	spi_shutdown_chip(dws);

	free_irq(dws->irq, dws->master);
	}
	EXPORT_SYMBOL_GPL(dw_spi_remove_host);

	int dw_spi_suspend_host(struct dw_spi *dws)
	{
	int ret;

	ret = spi_master_suspend(dws->master);
	if (ret)
	return ret;

	spi_shutdown_chip(dws);
	return 0;
	}
	EXPORT_SYMBOL_GPL(dw_spi_suspend_host);

	int dw_spi_resume_host(struct dw_spi *dws)
	{
	int ret;

	spi_hw_init(&dws->master->dev, dws);
	ret = spi_master_resume(dws->master);
	if (ret)
	dev_err(&dws->master->dev, "fail to start queue (%d)\n", ret);
	return ret;
	}
	EXPORT_SYMBOL_GPL(dw_spi_resume_host);

	MODULE_AUTHOR("Feng Tang <feng.tang@intel.com>");
	MODULE_DESCRIPTION("Driver for DesignWare SPI controller core");
	MODULE_LICENSE("GPL v2");