// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   *  CLPS711X SPI bus driver
   *

   *  Copyright (C) 2012-2016 Alexander Shiyan <shc_work@mail.ru>

   */
  
  #include <linux/io.h>
  #include <linux/clk.h>

  #include <linux/gpio/consumer.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>

  #define DRIVER_NAME		"clps711x-spi"

  #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_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_master *master;

  	int irq, ret;

  	irq = platform_get_irq(pdev, 0);
  	if (irq < 0)
  		return irq;

  	master = spi_alloc_master(&pdev->dev, sizeof(*hw));
  	if (!master)

  		return -ENOMEM;

  	master->use_gpio_descriptors = true;

  	master->bus_num = -1;

  	master->mode_bits = SPI_CPHA | SPI_CS_HIGH;

  	master->bits_per_word_mask =  SPI_BPW_RANGE_MASK(1, 8);

  	master->dev.of_node = pdev->dev.of_node;

  	master->prepare_message = spi_clps711x_prepare_message;
  	master->transfer_one = spi_clps711x_transfer_one;

  
  	hw = spi_master_get_devdata(master);

  	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_compatible("cirrus,ep7209-syscon3");

  	if (IS_ERR(hw->syscon)) {
  		ret = PTR_ERR(hw->syscon);
  		goto err_out;
  	}

  	hw->syncio = devm_platform_ioremap_resource(pdev, 0);

  	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)

  		return 0;

  err_out:

  	spi_master_put(master);

  
  	return ret;
  }

  static const struct of_device_id clps711x_spi_dt_ids[] = {
  	{ .compatible = "cirrus,ep7209-spi", },
  	{ }
  };
  MODULE_DEVICE_TABLE(of, clps711x_spi_dt_ids);

  static struct platform_driver clps711x_spi_driver = {
  	.driver	= {
  		.name	= DRIVER_NAME,

  		.of_match_table = clps711x_spi_dt_ids,

  	},
  	.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);