/*

   * Marvell Orion SPI controller driver

   *
   * Author: Shadi Ammouri <shadi@marvell.com>
   * Copyright (C) 2007-2008 Marvell Ltd.
   *
   * 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/init.h>
  #include <linux/interrupt.h>
  #include <linux/delay.h>
  #include <linux/platform_device.h>
  #include <linux/err.h>
  #include <linux/io.h>
  #include <linux/spi/spi.h>
  #include <linux/spi/orion_spi.h>

  #include <linux/module.h>

  #include <asm/unaligned.h>
  
  #define DRIVER_NAME			"orion_spi"
  
  #define ORION_NUM_CHIPSELECTS		1 /* only one slave is supported*/
  #define ORION_SPI_WAIT_RDY_MAX_LOOP	2000 /* in usec */
  
  #define ORION_SPI_IF_CTRL_REG		0x00
  #define ORION_SPI_IF_CONFIG_REG		0x04
  #define ORION_SPI_DATA_OUT_REG		0x08
  #define ORION_SPI_DATA_IN_REG		0x0c
  #define ORION_SPI_INT_CAUSE_REG		0x10
  
  #define ORION_SPI_IF_8_16_BIT_MODE	(1 << 5)
  #define ORION_SPI_CLK_PRESCALE_MASK	0x1F
  
  struct orion_spi {
  	struct work_struct	work;
  
  	/* Lock access to transfer list.	*/
  	spinlock_t		lock;
  
  	struct list_head	msg_queue;
  	struct spi_master	*master;
  	void __iomem		*base;
  	unsigned int		max_speed;
  	unsigned int		min_speed;
  	struct orion_spi_info	*spi_info;
  };
  
  static struct workqueue_struct *orion_spi_wq;
  
  static inline void __iomem *spi_reg(struct orion_spi *orion_spi, u32 reg)
  {
  	return orion_spi->base + reg;
  }
  
  static inline void
  orion_spi_setbits(struct orion_spi *orion_spi, u32 reg, u32 mask)
  {
  	void __iomem *reg_addr = spi_reg(orion_spi, reg);
  	u32 val;
  
  	val = readl(reg_addr);
  	val |= mask;
  	writel(val, reg_addr);
  }
  
  static inline void
  orion_spi_clrbits(struct orion_spi *orion_spi, u32 reg, u32 mask)
  {
  	void __iomem *reg_addr = spi_reg(orion_spi, reg);
  	u32 val;
  
  	val = readl(reg_addr);
  	val &= ~mask;
  	writel(val, reg_addr);
  }
  
  static int orion_spi_set_transfer_size(struct orion_spi *orion_spi, int size)
  {
  	if (size == 16) {
  		orion_spi_setbits(orion_spi, ORION_SPI_IF_CONFIG_REG,
  				  ORION_SPI_IF_8_16_BIT_MODE);
  	} else if (size == 8) {
  		orion_spi_clrbits(orion_spi, ORION_SPI_IF_CONFIG_REG,
  				  ORION_SPI_IF_8_16_BIT_MODE);
  	} else {
  		pr_debug("Bad bits per word value %d (only 8 or 16 are "
  			 "allowed).
  ", size);
  		return -EINVAL;
  	}
  
  	return 0;
  }
  
  static int orion_spi_baudrate_set(struct spi_device *spi, unsigned int speed)
  {
  	u32 tclk_hz;
  	u32 rate;
  	u32 prescale;
  	u32 reg;
  	struct orion_spi *orion_spi;
  
  	orion_spi = spi_master_get_devdata(spi->master);
  
  	tclk_hz = orion_spi->spi_info->tclk;
  
  	/*
  	 * the supported rates are: 4,6,8...30
  	 * round up as we look for equal or less speed
  	 */
  	rate = DIV_ROUND_UP(tclk_hz, speed);
  	rate = roundup(rate, 2);
  
  	/* check if requested speed is too small */
  	if (rate > 30)
  		return -EINVAL;
  
  	if (rate < 4)
  		rate = 4;
  
  	/* Convert the rate to SPI clock divisor value.	*/
  	prescale = 0x10 + rate/2;
  
  	reg = readl(spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
  	reg = ((reg & ~ORION_SPI_CLK_PRESCALE_MASK) | prescale);
  	writel(reg, spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
  
  	return 0;
  }
  
  /*
   * called only when no transfer is active on the bus
   */
  static int
  orion_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
  {
  	struct orion_spi *orion_spi;
  	unsigned int speed = spi->max_speed_hz;
  	unsigned int bits_per_word = spi->bits_per_word;
  	int	rc;
  
  	orion_spi = spi_master_get_devdata(spi->master);
  
  	if ((t != NULL) && t->speed_hz)
  		speed = t->speed_hz;
  
  	if ((t != NULL) && t->bits_per_word)
  		bits_per_word = t->bits_per_word;
  
  	rc = orion_spi_baudrate_set(spi, speed);
  	if (rc)
  		return rc;
  
  	return orion_spi_set_transfer_size(orion_spi, bits_per_word);
  }
  
  static void orion_spi_set_cs(struct orion_spi *orion_spi, int enable)
  {
  	if (enable)
  		orion_spi_setbits(orion_spi, ORION_SPI_IF_CTRL_REG, 0x1);
  	else
  		orion_spi_clrbits(orion_spi, ORION_SPI_IF_CTRL_REG, 0x1);
  }
  
  static inline int orion_spi_wait_till_ready(struct orion_spi *orion_spi)
  {
  	int i;
  
  	for (i = 0; i < ORION_SPI_WAIT_RDY_MAX_LOOP; i++) {
  		if (readl(spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG)))
  			return 1;
  		else
  			udelay(1);
  	}
  
  	return -1;
  }
  
  static inline int
  orion_spi_write_read_8bit(struct spi_device *spi,
  			  const u8 **tx_buf, u8 **rx_buf)
  {
  	void __iomem *tx_reg, *rx_reg, *int_reg;
  	struct orion_spi *orion_spi;
  
  	orion_spi = spi_master_get_devdata(spi->master);
  	tx_reg = spi_reg(orion_spi, ORION_SPI_DATA_OUT_REG);
  	rx_reg = spi_reg(orion_spi, ORION_SPI_DATA_IN_REG);
  	int_reg = spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG);
  
  	/* clear the interrupt cause register */
  	writel(0x0, int_reg);
  
  	if (tx_buf && *tx_buf)
  		writel(*(*tx_buf)++, tx_reg);
  	else
  		writel(0, tx_reg);
  
  	if (orion_spi_wait_till_ready(orion_spi) < 0) {
  		dev_err(&spi->dev, "TXS timed out
  ");
  		return -1;
  	}
  
  	if (rx_buf && *rx_buf)
  		*(*rx_buf)++ = readl(rx_reg);
  
  	return 1;
  }
  
  static inline int
  orion_spi_write_read_16bit(struct spi_device *spi,
  			   const u16 **tx_buf, u16 **rx_buf)
  {
  	void __iomem *tx_reg, *rx_reg, *int_reg;
  	struct orion_spi *orion_spi;
  
  	orion_spi = spi_master_get_devdata(spi->master);
  	tx_reg = spi_reg(orion_spi, ORION_SPI_DATA_OUT_REG);
  	rx_reg = spi_reg(orion_spi, ORION_SPI_DATA_IN_REG);
  	int_reg = spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG);
  
  	/* clear the interrupt cause register */
  	writel(0x0, int_reg);
  
  	if (tx_buf && *tx_buf)
  		writel(__cpu_to_le16(get_unaligned((*tx_buf)++)), tx_reg);
  	else
  		writel(0, tx_reg);
  
  	if (orion_spi_wait_till_ready(orion_spi) < 0) {
  		dev_err(&spi->dev, "TXS timed out
  ");
  		return -1;
  	}
  
  	if (rx_buf && *rx_buf)
  		put_unaligned(__le16_to_cpu(readl(rx_reg)), (*rx_buf)++);
  
  	return 1;
  }
  
  static unsigned int
  orion_spi_write_read(struct spi_device *spi, struct spi_transfer *xfer)
  {
  	struct orion_spi *orion_spi;
  	unsigned int count;
  	int word_len;
  
  	orion_spi = spi_master_get_devdata(spi->master);
  	word_len = spi->bits_per_word;
  	count = xfer->len;
  
  	if (word_len == 8) {
  		const u8 *tx = xfer->tx_buf;
  		u8 *rx = xfer->rx_buf;
  
  		do {
  			if (orion_spi_write_read_8bit(spi, &tx, &rx) < 0)
  				goto out;
  			count--;
  		} while (count);
  	} else if (word_len == 16) {
  		const u16 *tx = xfer->tx_buf;
  		u16 *rx = xfer->rx_buf;
  
  		do {
  			if (orion_spi_write_read_16bit(spi, &tx, &rx) < 0)
  				goto out;
  			count -= 2;
  		} while (count);
  	}
  
  out:
  	return xfer->len - count;
  }
  
  
  static void orion_spi_work(struct work_struct *work)
  {
  	struct orion_spi *orion_spi =
  		container_of(work, struct orion_spi, work);
  
  	spin_lock_irq(&orion_spi->lock);
  	while (!list_empty(&orion_spi->msg_queue)) {
  		struct spi_message *m;
  		struct spi_device *spi;
  		struct spi_transfer *t = NULL;
  		int par_override = 0;
  		int status = 0;
  		int cs_active = 0;
  
  		m = container_of(orion_spi->msg_queue.next, struct spi_message,
  				 queue);
  
  		list_del_init(&m->queue);
  		spin_unlock_irq(&orion_spi->lock);
  
  		spi = m->spi;
  
  		/* Load defaults */
  		status = orion_spi_setup_transfer(spi, NULL);
  
  		if (status < 0)
  			goto msg_done;
  
  		list_for_each_entry(t, &m->transfers, transfer_list) {
  			if (par_override || t->speed_hz || t->bits_per_word) {
  				par_override = 1;
  				status = orion_spi_setup_transfer(spi, t);
  				if (status < 0)
  					break;
  				if (!t->speed_hz && !t->bits_per_word)
  					par_override = 0;
  			}
  
  			if (!cs_active) {
  				orion_spi_set_cs(orion_spi, 1);
  				cs_active = 1;
  			}
  
  			if (t->len)
  				m->actual_length +=
  					orion_spi_write_read(spi, t);
  
  			if (t->delay_usecs)
  				udelay(t->delay_usecs);
  
  			if (t->cs_change) {
  				orion_spi_set_cs(orion_spi, 0);
  				cs_active = 0;
  			}
  		}
  
  msg_done:
  		if (cs_active)
  			orion_spi_set_cs(orion_spi, 0);
  
  		m->status = status;
  		m->complete(m->context);
  
  		spin_lock_irq(&orion_spi->lock);
  	}
  
  	spin_unlock_irq(&orion_spi->lock);
  }
  
  static int __init orion_spi_reset(struct orion_spi *orion_spi)
  {
  	/* Verify that the CS is deasserted */
  	orion_spi_set_cs(orion_spi, 0);
  
  	return 0;
  }
  
  static int orion_spi_setup(struct spi_device *spi)
  {
  	struct orion_spi *orion_spi;
  
  	orion_spi = spi_master_get_devdata(spi->master);

  	/* Fix ac timing if required.   */
  	if (orion_spi->spi_info->enable_clock_fix)
  		orion_spi_setbits(orion_spi, ORION_SPI_IF_CONFIG_REG,
  				  (1 << 14));

  	if ((spi->max_speed_hz == 0)
  			|| (spi->max_speed_hz > orion_spi->max_speed))
  		spi->max_speed_hz = orion_spi->max_speed;
  
  	if (spi->max_speed_hz < orion_spi->min_speed) {
  		dev_err(&spi->dev, "setup: requested speed too low %d Hz
  ",
  			spi->max_speed_hz);
  		return -EINVAL;
  	}
  
  	/*
  	 * baudrate & width will be set orion_spi_setup_transfer
  	 */
  	return 0;
  }
  
  static int orion_spi_transfer(struct spi_device *spi, struct spi_message *m)
  {
  	struct orion_spi *orion_spi;
  	struct spi_transfer *t = NULL;
  	unsigned long flags;
  
  	m->actual_length = 0;
  	m->status = 0;
  
  	/* reject invalid messages and transfers */
  	if (list_empty(&m->transfers) || !m->complete)
  		return -EINVAL;
  
  	orion_spi = spi_master_get_devdata(spi->master);
  
  	list_for_each_entry(t, &m->transfers, transfer_list) {
  		unsigned int bits_per_word = spi->bits_per_word;
  
  		if (t->tx_buf == NULL && t->rx_buf == NULL && t->len) {
  			dev_err(&spi->dev,
  				"message rejected : "
  				"invalid transfer data buffers
  ");
  			goto msg_rejected;
  		}

  		if (t->bits_per_word)

  			bits_per_word = t->bits_per_word;
  
  		if ((bits_per_word != 8) && (bits_per_word != 16)) {
  			dev_err(&spi->dev,
  				"message rejected : "
  				"invalid transfer bits_per_word (%d bits)
  ",
  				bits_per_word);
  			goto msg_rejected;
  		}
  		/*make sure buffer length is even when working in 16 bit mode*/

  		if ((t->bits_per_word == 16) && (t->len & 1)) {

  			dev_err(&spi->dev,
  				"message rejected : "
  				"odd data length (%d) while in 16 bit mode
  ",
  				t->len);
  			goto msg_rejected;
  		}

  		if (t->speed_hz && t->speed_hz < orion_spi->min_speed) {

  			dev_err(&spi->dev,
  				"message rejected : "
  				"device min speed (%d Hz) exceeds "
  				"required transfer speed (%d Hz)
  ",
  				orion_spi->min_speed, t->speed_hz);
  			goto msg_rejected;
  		}
  	}
  
  
  	spin_lock_irqsave(&orion_spi->lock, flags);
  	list_add_tail(&m->queue, &orion_spi->msg_queue);
  	queue_work(orion_spi_wq, &orion_spi->work);
  	spin_unlock_irqrestore(&orion_spi->lock, flags);
  
  	return 0;
  msg_rejected:
  	/* Message rejected and not queued */
  	m->status = -EINVAL;
  	if (m->complete)
  		m->complete(m->context);
  	return -EINVAL;
  }
  
  static int __init orion_spi_probe(struct platform_device *pdev)
  {
  	struct spi_master *master;
  	struct orion_spi *spi;
  	struct resource *r;
  	struct orion_spi_info *spi_info;
  	int status = 0;
  
  	spi_info = pdev->dev.platform_data;
  
  	master = spi_alloc_master(&pdev->dev, sizeof *spi);
  	if (master == NULL) {
  		dev_dbg(&pdev->dev, "master allocation failed
  ");
  		return -ENOMEM;
  	}
  
  	if (pdev->id != -1)
  		master->bus_num = pdev->id;

  	/* we support only mode 0, and no options */
  	master->mode_bits = 0;

  	master->setup = orion_spi_setup;
  	master->transfer = orion_spi_transfer;
  	master->num_chipselect = ORION_NUM_CHIPSELECTS;
  
  	dev_set_drvdata(&pdev->dev, master);
  
  	spi = spi_master_get_devdata(master);
  	spi->master = master;
  	spi->spi_info = spi_info;
  
  	spi->max_speed = DIV_ROUND_UP(spi_info->tclk, 4);
  	spi->min_speed = DIV_ROUND_UP(spi_info->tclk, 30);
  
  	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (r == NULL) {
  		status = -ENODEV;
  		goto out;
  	}

  	if (!request_mem_region(r->start, resource_size(r),

  				dev_name(&pdev->dev))) {

  		status = -EBUSY;
  		goto out;
  	}
  	spi->base = ioremap(r->start, SZ_1K);
  
  	INIT_WORK(&spi->work, orion_spi_work);
  
  	spin_lock_init(&spi->lock);
  	INIT_LIST_HEAD(&spi->msg_queue);
  
  	if (orion_spi_reset(spi) < 0)
  		goto out_rel_mem;
  
  	status = spi_register_master(master);
  	if (status < 0)
  		goto out_rel_mem;
  
  	return status;
  
  out_rel_mem:

  	release_mem_region(r->start, resource_size(r));

  
  out:
  	spi_master_put(master);
  	return status;
  }
  
  
  static int __exit orion_spi_remove(struct platform_device *pdev)
  {
  	struct spi_master *master;
  	struct orion_spi *spi;
  	struct resource *r;
  
  	master = dev_get_drvdata(&pdev->dev);
  	spi = spi_master_get_devdata(master);
  
  	cancel_work_sync(&spi->work);
  
  	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);

  	release_mem_region(r->start, resource_size(r));

  
  	spi_unregister_master(master);
  
  	return 0;
  }
  
  MODULE_ALIAS("platform:" DRIVER_NAME);
  
  static struct platform_driver orion_spi_driver = {
  	.driver = {
  		.name	= DRIVER_NAME,
  		.owner	= THIS_MODULE,
  	},
  	.remove		= __exit_p(orion_spi_remove),
  };
  
  static int __init orion_spi_init(void)
  {
  	orion_spi_wq = create_singlethread_workqueue(
  				orion_spi_driver.driver.name);
  	if (orion_spi_wq == NULL)
  		return -ENOMEM;
  
  	return platform_driver_probe(&orion_spi_driver, orion_spi_probe);
  }
  module_init(orion_spi_init);
  
  static void __exit orion_spi_exit(void)
  {
  	flush_workqueue(orion_spi_wq);
  	platform_driver_unregister(&orion_spi_driver);
  
  	destroy_workqueue(orion_spi_wq);
  }
  module_exit(orion_spi_exit);
  
  MODULE_DESCRIPTION("Orion SPI driver");
  MODULE_AUTHOR("Shadi Ammouri <shadi@marvell.com>");
  MODULE_LICENSE("GPL");