/*
   * MPC52xx PSC in SPI mode driver.
   *
   * Maintainer: Dragos Carp
   *
   * Copyright (C) 2006 TOPTICA Photonics AG.
   *
   * 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.
   */
  
  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/errno.h>
  #include <linux/interrupt.h>
  #include <linux/of_address.h>
  #include <linux/of_platform.h>
  #include <linux/workqueue.h>
  #include <linux/completion.h>
  #include <linux/io.h>
  #include <linux/delay.h>
  #include <linux/spi/spi.h>
  #include <linux/fsl_devices.h>
  #include <linux/slab.h>
  
  #include <asm/mpc52xx.h>
  #include <asm/mpc52xx_psc.h>
  
  #define MCLK 20000000 /* PSC port MClk in hz */
  
  struct mpc52xx_psc_spi {
  	/* fsl_spi_platform data */
  	void (*cs_control)(struct spi_device *spi, bool on);
  	u32 sysclk;
  
  	/* driver internal data */
  	struct mpc52xx_psc __iomem *psc;
  	struct mpc52xx_psc_fifo __iomem *fifo;
  	unsigned int irq;
  	u8 bits_per_word;
  	u8 busy;
  
  	struct workqueue_struct *workqueue;
  	struct work_struct work;
  
  	struct list_head queue;
  	spinlock_t lock;
  
  	struct completion done;
  };
  
  /* controller state */
  struct mpc52xx_psc_spi_cs {
  	int bits_per_word;
  	int speed_hz;
  };
  
  /* set clock freq, clock ramp, bits per work
   * if t is NULL then reset the values to the default values
   */
  static int mpc52xx_psc_spi_transfer_setup(struct spi_device *spi,
  		struct spi_transfer *t)
  {
  	struct mpc52xx_psc_spi_cs *cs = spi->controller_state;
  
  	cs->speed_hz = (t && t->speed_hz)
  			? t->speed_hz : spi->max_speed_hz;
  	cs->bits_per_word = (t && t->bits_per_word)
  			? t->bits_per_word : spi->bits_per_word;
  	cs->bits_per_word = ((cs->bits_per_word + 7) / 8) * 8;
  	return 0;
  }
  
  static void mpc52xx_psc_spi_activate_cs(struct spi_device *spi)
  {
  	struct mpc52xx_psc_spi_cs *cs = spi->controller_state;
  	struct mpc52xx_psc_spi *mps = spi_master_get_devdata(spi->master);
  	struct mpc52xx_psc __iomem *psc = mps->psc;
  	u32 sicr;
  	u16 ccr;
  
  	sicr = in_be32(&psc->sicr);
  
  	/* Set clock phase and polarity */
  	if (spi->mode & SPI_CPHA)
  		sicr |= 0x00001000;
  	else
  		sicr &= ~0x00001000;
  	if (spi->mode & SPI_CPOL)
  		sicr |= 0x00002000;
  	else
  		sicr &= ~0x00002000;
  
  	if (spi->mode & SPI_LSB_FIRST)
  		sicr |= 0x10000000;
  	else
  		sicr &= ~0x10000000;
  	out_be32(&psc->sicr, sicr);
  
  	/* Set clock frequency and bits per word
  	 * Because psc->ccr is defined as 16bit register instead of 32bit
  	 * just set the lower byte of BitClkDiv
  	 */
  	ccr = in_be16((u16 __iomem *)&psc->ccr);
  	ccr &= 0xFF00;
  	if (cs->speed_hz)
  		ccr |= (MCLK / cs->speed_hz - 1) & 0xFF;
  	else /* by default SPI Clk 1MHz */
  		ccr |= (MCLK / 1000000 - 1) & 0xFF;
  	out_be16((u16 __iomem *)&psc->ccr, ccr);
  	mps->bits_per_word = cs->bits_per_word;
  
  	if (mps->cs_control)
  		mps->cs_control(spi, (spi->mode & SPI_CS_HIGH) ? 1 : 0);
  }
  
  static void mpc52xx_psc_spi_deactivate_cs(struct spi_device *spi)
  {
  	struct mpc52xx_psc_spi *mps = spi_master_get_devdata(spi->master);
  
  	if (mps->cs_control)
  		mps->cs_control(spi, (spi->mode & SPI_CS_HIGH) ? 0 : 1);
  }
  
  #define MPC52xx_PSC_BUFSIZE (MPC52xx_PSC_RFNUM_MASK + 1)
  /* wake up when 80% fifo full */
  #define MPC52xx_PSC_RFALARM (MPC52xx_PSC_BUFSIZE * 20 / 100)
  
  static int mpc52xx_psc_spi_transfer_rxtx(struct spi_device *spi,
  						struct spi_transfer *t)
  {
  	struct mpc52xx_psc_spi *mps = spi_master_get_devdata(spi->master);
  	struct mpc52xx_psc __iomem *psc = mps->psc;
  	struct mpc52xx_psc_fifo __iomem *fifo = mps->fifo;
  	unsigned rb = 0;	/* number of bytes receieved */
  	unsigned sb = 0;	/* number of bytes sent */
  	unsigned char *rx_buf = (unsigned char *)t->rx_buf;
  	unsigned char *tx_buf = (unsigned char *)t->tx_buf;
  	unsigned rfalarm;
  	unsigned send_at_once = MPC52xx_PSC_BUFSIZE;
  	unsigned recv_at_once;
  	int last_block = 0;
  
  	if (!t->tx_buf && !t->rx_buf && t->len)
  		return -EINVAL;
  
  	/* enable transmiter/receiver */
  	out_8(&psc->command, MPC52xx_PSC_TX_ENABLE | MPC52xx_PSC_RX_ENABLE);
  	while (rb < t->len) {
  		if (t->len - rb > MPC52xx_PSC_BUFSIZE) {
  			rfalarm = MPC52xx_PSC_RFALARM;
  			last_block = 0;
  		} else {
  			send_at_once = t->len - sb;
  			rfalarm = MPC52xx_PSC_BUFSIZE - (t->len - rb);
  			last_block = 1;
  		}
  
  		dev_dbg(&spi->dev, "send %d bytes...
  ", send_at_once);
  		for (; send_at_once; sb++, send_at_once--) {
  			/* set EOF flag before the last word is sent */
  			if (send_at_once == 1 && last_block)
  				out_8(&psc->ircr2, 0x01);
  
  			if (tx_buf)
  				out_8(&psc->mpc52xx_psc_buffer_8, tx_buf[sb]);
  			else
  				out_8(&psc->mpc52xx_psc_buffer_8, 0);
  		}
  
  
  		/* enable interrupts and wait for wake up
  		 * if just one byte is expected the Rx FIFO genererates no
  		 * FFULL interrupt, so activate the RxRDY interrupt
  		 */
  		out_8(&psc->command, MPC52xx_PSC_SEL_MODE_REG_1);
  		if (t->len - rb == 1) {
  			out_8(&psc->mode, 0);
  		} else {
  			out_8(&psc->mode, MPC52xx_PSC_MODE_FFULL);
  			out_be16(&fifo->rfalarm, rfalarm);
  		}
  		out_be16(&psc->mpc52xx_psc_imr, MPC52xx_PSC_IMR_RXRDY);
  		wait_for_completion(&mps->done);
  		recv_at_once = in_be16(&fifo->rfnum);
  		dev_dbg(&spi->dev, "%d bytes received
  ", recv_at_once);
  
  		send_at_once = recv_at_once;
  		if (rx_buf) {
  			for (; recv_at_once; rb++, recv_at_once--)
  				rx_buf[rb] = in_8(&psc->mpc52xx_psc_buffer_8);
  		} else {
  			for (; recv_at_once; rb++, recv_at_once--)
  				in_8(&psc->mpc52xx_psc_buffer_8);
  		}
  	}
  	/* disable transmiter/receiver */
  	out_8(&psc->command, MPC52xx_PSC_TX_DISABLE | MPC52xx_PSC_RX_DISABLE);
  
  	return 0;
  }
  
  static void mpc52xx_psc_spi_work(struct work_struct *work)
  {
  	struct mpc52xx_psc_spi *mps =
  		container_of(work, struct mpc52xx_psc_spi, work);
  
  	spin_lock_irq(&mps->lock);
  	mps->busy = 1;
  	while (!list_empty(&mps->queue)) {
  		struct spi_message *m;
  		struct spi_device *spi;
  		struct spi_transfer *t = NULL;
  		unsigned cs_change;
  		int status;
  
  		m = container_of(mps->queue.next, struct spi_message, queue);
  		list_del_init(&m->queue);
  		spin_unlock_irq(&mps->lock);
  
  		spi = m->spi;
  		cs_change = 1;
  		status = 0;
  		list_for_each_entry (t, &m->transfers, transfer_list) {
  			if (t->bits_per_word || t->speed_hz) {
  				status = mpc52xx_psc_spi_transfer_setup(spi, t);
  				if (status < 0)
  					break;
  			}
  
  			if (cs_change)
  				mpc52xx_psc_spi_activate_cs(spi);
  			cs_change = t->cs_change;
  
  			status = mpc52xx_psc_spi_transfer_rxtx(spi, t);
  			if (status)
  				break;
  			m->actual_length += t->len;
  
  			if (t->delay_usecs)
  				udelay(t->delay_usecs);
  
  			if (cs_change)
  				mpc52xx_psc_spi_deactivate_cs(spi);
  		}
  
  		m->status = status;
  		m->complete(m->context);
  
  		if (status || !cs_change)
  			mpc52xx_psc_spi_deactivate_cs(spi);
  
  		mpc52xx_psc_spi_transfer_setup(spi, NULL);
  
  		spin_lock_irq(&mps->lock);
  	}
  	mps->busy = 0;
  	spin_unlock_irq(&mps->lock);
  }
  
  static int mpc52xx_psc_spi_setup(struct spi_device *spi)
  {
  	struct mpc52xx_psc_spi *mps = spi_master_get_devdata(spi->master);
  	struct mpc52xx_psc_spi_cs *cs = spi->controller_state;
  	unsigned long flags;
  
  	if (spi->bits_per_word%8)
  		return -EINVAL;
  
  	if (!cs) {
  		cs = kzalloc(sizeof *cs, GFP_KERNEL);
  		if (!cs)
  			return -ENOMEM;
  		spi->controller_state = cs;
  	}
  
  	cs->bits_per_word = spi->bits_per_word;
  	cs->speed_hz = spi->max_speed_hz;
  
  	spin_lock_irqsave(&mps->lock, flags);
  	if (!mps->busy)
  		mpc52xx_psc_spi_deactivate_cs(spi);
  	spin_unlock_irqrestore(&mps->lock, flags);
  
  	return 0;
  }
  
  static int mpc52xx_psc_spi_transfer(struct spi_device *spi,
  		struct spi_message *m)
  {
  	struct mpc52xx_psc_spi *mps = spi_master_get_devdata(spi->master);
  	unsigned long flags;
  
  	m->actual_length = 0;
  	m->status = -EINPROGRESS;
  
  	spin_lock_irqsave(&mps->lock, flags);
  	list_add_tail(&m->queue, &mps->queue);
  	queue_work(mps->workqueue, &mps->work);
  	spin_unlock_irqrestore(&mps->lock, flags);
  
  	return 0;
  }
  
  static void mpc52xx_psc_spi_cleanup(struct spi_device *spi)
  {
  	kfree(spi->controller_state);
  }
  
  static int mpc52xx_psc_spi_port_config(int psc_id, struct mpc52xx_psc_spi *mps)
  {
  	struct mpc52xx_psc __iomem *psc = mps->psc;
  	struct mpc52xx_psc_fifo __iomem *fifo = mps->fifo;
  	u32 mclken_div;
  	int ret;
  
  	/* default sysclk is 512MHz */
  	mclken_div = (mps->sysclk ? mps->sysclk : 512000000) / MCLK;
  	ret = mpc52xx_set_psc_clkdiv(psc_id, mclken_div);
  	if (ret)
  		return ret;
  
  	/* Reset the PSC into a known state */
  	out_8(&psc->command, MPC52xx_PSC_RST_RX);
  	out_8(&psc->command, MPC52xx_PSC_RST_TX);
  	out_8(&psc->command, MPC52xx_PSC_TX_DISABLE | MPC52xx_PSC_RX_DISABLE);
  
  	/* Disable interrupts, interrupts are based on alarm level */
  	out_be16(&psc->mpc52xx_psc_imr, 0);
  	out_8(&psc->command, MPC52xx_PSC_SEL_MODE_REG_1);
  	out_8(&fifo->rfcntl, 0);
  	out_8(&psc->mode, MPC52xx_PSC_MODE_FFULL);
  
  	/* Configure 8bit codec mode as a SPI master and use EOF flags */
  	/* SICR_SIM_CODEC8|SICR_GENCLK|SICR_SPI|SICR_MSTR|SICR_USEEOF */
  	out_be32(&psc->sicr, 0x0180C800);
  	out_be16((u16 __iomem *)&psc->ccr, 0x070F); /* default SPI Clk 1MHz */
  
  	/* Set 2ms DTL delay */
  	out_8(&psc->ctur, 0x00);
  	out_8(&psc->ctlr, 0x84);
  
  	mps->bits_per_word = 8;
  
  	return 0;
  }
  
  static irqreturn_t mpc52xx_psc_spi_isr(int irq, void *dev_id)
  {
  	struct mpc52xx_psc_spi *mps = (struct mpc52xx_psc_spi *)dev_id;
  	struct mpc52xx_psc __iomem *psc = mps->psc;
  
  	/* disable interrupt and wake up the work queue */
  	if (in_be16(&psc->mpc52xx_psc_isr) & MPC52xx_PSC_IMR_RXRDY) {
  		out_be16(&psc->mpc52xx_psc_imr, 0);
  		complete(&mps->done);
  		return IRQ_HANDLED;
  	}
  	return IRQ_NONE;
  }
  
  /* bus_num is used only for the case dev->platform_data == NULL */
  static int mpc52xx_psc_spi_do_probe(struct device *dev, u32 regaddr,
  				u32 size, unsigned int irq, s16 bus_num)
  {
  	struct fsl_spi_platform_data *pdata = dev_get_platdata(dev);
  	struct mpc52xx_psc_spi *mps;
  	struct spi_master *master;
  	int ret;
  
  	master = spi_alloc_master(dev, sizeof *mps);
  	if (master == NULL)
  		return -ENOMEM;
  
  	dev_set_drvdata(dev, master);
  	mps = spi_master_get_devdata(master);
  
  	/* the spi->mode bits understood by this driver: */
  	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LSB_FIRST;
  
  	mps->irq = irq;
  	if (pdata == NULL) {
  		dev_warn(dev,
  			 "probe called without platform data, no cs_control function will be called
  ");
  		mps->cs_control = NULL;
  		mps->sysclk = 0;
  		master->bus_num = bus_num;
  		master->num_chipselect = 255;
  	} else {
  		mps->cs_control = pdata->cs_control;
  		mps->sysclk = pdata->sysclk;
  		master->bus_num = pdata->bus_num;
  		master->num_chipselect = pdata->max_chipselect;
  	}
  	master->setup = mpc52xx_psc_spi_setup;
  	master->transfer = mpc52xx_psc_spi_transfer;
  	master->cleanup = mpc52xx_psc_spi_cleanup;
  	master->dev.of_node = dev->of_node;
  
  	mps->psc = ioremap(regaddr, size);
  	if (!mps->psc) {
  		dev_err(dev, "could not ioremap I/O port range
  ");
  		ret = -EFAULT;
  		goto free_master;
  	}
  	/* On the 5200, fifo regs are immediately ajacent to the psc regs */
  	mps->fifo = ((void __iomem *)mps->psc) + sizeof(struct mpc52xx_psc);
  
  	ret = request_irq(mps->irq, mpc52xx_psc_spi_isr, 0, "mpc52xx-psc-spi",
  				mps);
  	if (ret)
  		goto free_master;
  
  	ret = mpc52xx_psc_spi_port_config(master->bus_num, mps);
  	if (ret < 0) {
  		dev_err(dev, "can't configure PSC! Is it capable of SPI?
  ");
  		goto free_irq;
  	}
  
  	spin_lock_init(&mps->lock);
  	init_completion(&mps->done);
  	INIT_WORK(&mps->work, mpc52xx_psc_spi_work);
  	INIT_LIST_HEAD(&mps->queue);
  
  	mps->workqueue = create_singlethread_workqueue(
  		dev_name(master->dev.parent));
  	if (mps->workqueue == NULL) {
  		ret = -EBUSY;
  		goto free_irq;
  	}
  
  	ret = spi_register_master(master);
  	if (ret < 0)
  		goto unreg_master;
  
  	return ret;
  
  unreg_master:
  	destroy_workqueue(mps->workqueue);
  free_irq:
  	free_irq(mps->irq, mps);
  free_master:
  	if (mps->psc)
  		iounmap(mps->psc);
  	spi_master_put(master);
  
  	return ret;
  }
  
  static int mpc52xx_psc_spi_of_probe(struct platform_device *op)
  {
  	const u32 *regaddr_p;
  	u64 regaddr64, size64;
  	s16 id = -1;
  
  	regaddr_p = of_get_address(op->dev.of_node, 0, &size64, NULL);
  	if (!regaddr_p) {
  		dev_err(&op->dev, "Invalid PSC address
  ");
  		return -EINVAL;
  	}
  	regaddr64 = of_translate_address(op->dev.of_node, regaddr_p);
  
  	/* get PSC id (1..6, used by port_config) */
  	if (op->dev.platform_data == NULL) {
  		const u32 *psc_nump;
  
  		psc_nump = of_get_property(op->dev.of_node, "cell-index", NULL);
  		if (!psc_nump || *psc_nump > 5) {
  			dev_err(&op->dev, "Invalid cell-index property
  ");
  			return -EINVAL;
  		}
  		id = *psc_nump + 1;
  	}
  
  	return mpc52xx_psc_spi_do_probe(&op->dev, (u32)regaddr64, (u32)size64,
  				irq_of_parse_and_map(op->dev.of_node, 0), id);
  }
  
  static int mpc52xx_psc_spi_of_remove(struct platform_device *op)
  {
  	struct spi_master *master = spi_master_get(platform_get_drvdata(op));
  	struct mpc52xx_psc_spi *mps = spi_master_get_devdata(master);
  
  	flush_workqueue(mps->workqueue);
  	destroy_workqueue(mps->workqueue);
  	spi_unregister_master(master);
  	free_irq(mps->irq, mps);
  	if (mps->psc)
  		iounmap(mps->psc);
  	spi_master_put(master);
  
  	return 0;
  }
  
  static const struct of_device_id mpc52xx_psc_spi_of_match[] = {
  	{ .compatible = "fsl,mpc5200-psc-spi", },
  	{ .compatible = "mpc5200-psc-spi", }, /* old */
  	{}
  };
  
  MODULE_DEVICE_TABLE(of, mpc52xx_psc_spi_of_match);
  
  static struct platform_driver mpc52xx_psc_spi_of_driver = {
  	.probe = mpc52xx_psc_spi_of_probe,
  	.remove = mpc52xx_psc_spi_of_remove,
  	.driver = {
  		.name = "mpc52xx-psc-spi",
  		.owner = THIS_MODULE,
  		.of_match_table = mpc52xx_psc_spi_of_match,
  	},
  };
  module_platform_driver(mpc52xx_psc_spi_of_driver);
  
  MODULE_AUTHOR("Dragos Carp");
  MODULE_DESCRIPTION("MPC52xx PSC SPI Driver");
  MODULE_LICENSE("GPL");