/*
   *  CLPS711X SPI bus driver
   *
   *  Copyright (C) 2012-2014 Alexander Shiyan <shc_work@mail.ru>
   *
   * 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/io.h>
  #include <linux/clk.h>
  #include <linux/gpio.h>
  #include <linux/delay.h>
  #include <linux/module.h>
  #include <linux/interrupt.h>
  #include <linux/platform_device.h>
  #include <linux/regmap.h>
  #include <linux/mfd/syscon.h>
  #include <linux/mfd/syscon/clps711x.h>
  #include <linux/spi/spi.h>
  #include <linux/platform_data/spi-clps711x.h>
  
  #define DRIVER_NAME	"spi-clps711x"
  
  #define SYNCIO_FRMLEN(x)	((x) << 8)
  #define SYNCIO_TXFRMEN		(1 << 14)
  
  struct spi_clps711x_data {
  	void __iomem		*syncio;
  	struct regmap		*syscon;
  	struct clk		*spi_clk;
  
  	u8			*tx_buf;
  	u8			*rx_buf;
  	unsigned int		bpw;
  	int			len;
  };
  
  static int spi_clps711x_setup(struct spi_device *spi)
  {
  	/* We are expect that SPI-device is not selected */
  	gpio_direction_output(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
  
  	return 0;
  }
  
  static int spi_clps711x_prepare_message(struct spi_master *master,
  					struct spi_message *msg)
  {
  	struct spi_clps711x_data *hw = spi_master_get_devdata(master);
  	struct spi_device *spi = msg->spi;
  
  	/* Setup mode for transfer */
  	return regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCKNSEN,
  				  (spi->mode & SPI_CPHA) ?
  				  SYSCON3_ADCCKNSEN : 0);
  }
  
  static int spi_clps711x_transfer_one(struct spi_master *master,
  				     struct spi_device *spi,
  				     struct spi_transfer *xfer)
  {
  	struct spi_clps711x_data *hw = spi_master_get_devdata(master);
  	u8 data;
  
  	clk_set_rate(hw->spi_clk, xfer->speed_hz ? : spi->max_speed_hz);
  
  	hw->len = xfer->len;
  	hw->bpw = xfer->bits_per_word;
  	hw->tx_buf = (u8 *)xfer->tx_buf;
  	hw->rx_buf = (u8 *)xfer->rx_buf;
  
  	/* Initiate transfer */
  	data = hw->tx_buf ? *hw->tx_buf++ : 0;
  	writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN, hw->syncio);
  
  	return 1;
  }
  
  static irqreturn_t spi_clps711x_isr(int irq, void *dev_id)
  {
  	struct spi_master *master = dev_id;
  	struct spi_clps711x_data *hw = spi_master_get_devdata(master);
  	u8 data;
  
  	/* Handle RX */
  	data = readb(hw->syncio);
  	if (hw->rx_buf)
  		*hw->rx_buf++ = data;
  
  	/* Handle TX */
  	if (--hw->len > 0) {
  		data = hw->tx_buf ? *hw->tx_buf++ : 0;
  		writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN,
  		       hw->syncio);
  	} else
  		spi_finalize_current_transfer(master);
  
  	return IRQ_HANDLED;
  }
  
  static int spi_clps711x_probe(struct platform_device *pdev)
  {
  	struct spi_clps711x_data *hw;
  	struct spi_clps711x_pdata *pdata = dev_get_platdata(&pdev->dev);
  	struct spi_master *master;
  	struct resource *res;
  	int i, irq, ret;
  
  	if (!pdata) {
  		dev_err(&pdev->dev, "No platform data supplied
  ");
  		return -EINVAL;
  	}
  
  	if (pdata->num_chipselect < 1) {
  		dev_err(&pdev->dev, "At least one CS must be defined
  ");
  		return -EINVAL;
  	}
  
  	irq = platform_get_irq(pdev, 0);
  	if (irq < 0)
  		return irq;
  
  	master = spi_alloc_master(&pdev->dev, sizeof(*hw));
  	if (!master)
  		return -ENOMEM;
  
  	master->cs_gpios = devm_kzalloc(&pdev->dev, sizeof(int) *
  					pdata->num_chipselect, GFP_KERNEL);
  	if (!master->cs_gpios) {
  		ret = -ENOMEM;
  		goto err_out;
  	}
  
  	master->bus_num = pdev->id;
  	master->mode_bits = SPI_CPHA | SPI_CS_HIGH;
  	master->bits_per_word_mask =  SPI_BPW_RANGE_MASK(1, 8);
  	master->num_chipselect = pdata->num_chipselect;
  	master->setup = spi_clps711x_setup;
  	master->prepare_message = spi_clps711x_prepare_message;
  	master->transfer_one = spi_clps711x_transfer_one;
  
  	hw = spi_master_get_devdata(master);
  
  	for (i = 0; i < master->num_chipselect; i++) {
  		master->cs_gpios[i] = pdata->chipselect[i];
  		ret = devm_gpio_request(&pdev->dev, master->cs_gpios[i],
  					DRIVER_NAME);
  		if (ret) {
  			dev_err(&pdev->dev, "Can't get CS GPIO %i
  ", i);
  			goto err_out;
  		}
  	}
  
  	hw->spi_clk = devm_clk_get(&pdev->dev, NULL);
  	if (IS_ERR(hw->spi_clk)) {
  		ret = PTR_ERR(hw->spi_clk);
  		goto err_out;
  	}
  
  	hw->syscon = syscon_regmap_lookup_by_pdevname("syscon.3");
  	if (IS_ERR(hw->syscon)) {
  		ret = PTR_ERR(hw->syscon);
  		goto err_out;
  	}
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	hw->syncio = devm_ioremap_resource(&pdev->dev, res);
  	if (IS_ERR(hw->syncio)) {
  		ret = PTR_ERR(hw->syncio);
  		goto err_out;
  	}
  
  	/* Disable extended mode due hardware problems */
  	regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCON, 0);
  
  	/* Clear possible pending interrupt */
  	readl(hw->syncio);
  
  	ret = devm_request_irq(&pdev->dev, irq, spi_clps711x_isr, 0,
  			       dev_name(&pdev->dev), master);
  	if (ret)
  		goto err_out;
  
  	ret = devm_spi_register_master(&pdev->dev, master);
  	if (!ret) {
  		dev_info(&pdev->dev,
  			 "SPI bus driver initialized. Master clock %u Hz
  ",
  			 master->max_speed_hz);
  		return 0;
  	}
  
  	dev_err(&pdev->dev, "Failed to register master
  ");
  
  err_out:
  	spi_master_put(master);
  
  	return ret;
  }
  
  static struct platform_driver clps711x_spi_driver = {
  	.driver	= {
  		.name	= DRIVER_NAME,
  	},
  	.probe	= spi_clps711x_probe,
  };
  module_platform_driver(clps711x_spi_driver);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
  MODULE_DESCRIPTION("CLPS711X SPI bus driver");
  MODULE_ALIAS("platform:" DRIVER_NAME);