/*
   * NXP SC18IS602/603 SPI driver
   *
   * Copyright (C) Guenter Roeck <linux@roeck-us.net>
   *
   * 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.
   *
   * This program is distributed in the hope that 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/kernel.h>
  #include <linux/err.h>
  #include <linux/module.h>
  #include <linux/spi/spi.h>
  #include <linux/i2c.h>
  #include <linux/delay.h>
  #include <linux/pm_runtime.h>

  #include <linux/of_device.h>

  #include <linux/of.h>
  #include <linux/platform_data/sc18is602.h>

  #include <linux/gpio/consumer.h>

  
  enum chips { sc18is602, sc18is602b, sc18is603 };
  
  #define SC18IS602_BUFSIZ		200
  #define SC18IS602_CLOCK			7372000
  
  #define SC18IS602_MODE_CPHA		BIT(2)
  #define SC18IS602_MODE_CPOL		BIT(3)
  #define SC18IS602_MODE_LSB_FIRST	BIT(5)
  #define SC18IS602_MODE_CLOCK_DIV_4	0x0
  #define SC18IS602_MODE_CLOCK_DIV_16	0x1
  #define SC18IS602_MODE_CLOCK_DIV_64	0x2
  #define SC18IS602_MODE_CLOCK_DIV_128	0x3
  
  struct sc18is602 {
  	struct spi_master	*master;
  	struct device		*dev;
  	u8			ctrl;
  	u32			freq;
  	u32			speed;
  
  	/* I2C data */
  	struct i2c_client	*client;
  	enum chips		id;
  	u8			buffer[SC18IS602_BUFSIZ + 1];
  	int			tlen;	/* Data queued for tx in buffer */
  	int			rindex;	/* Receive data index in buffer */

  
  	struct gpio_desc	*reset;

  };
  
  static int sc18is602_wait_ready(struct sc18is602 *hw, int len)
  {
  	int i, err;
  	int usecs = 1000000 * len / hw->speed + 1;
  	u8 dummy[1];
  
  	for (i = 0; i < 10; i++) {
  		err = i2c_master_recv(hw->client, dummy, 1);
  		if (err >= 0)
  			return 0;
  		usleep_range(usecs, usecs * 2);
  	}
  	return -ETIMEDOUT;
  }
  
  static int sc18is602_txrx(struct sc18is602 *hw, struct spi_message *msg,
  			  struct spi_transfer *t, bool do_transfer)
  {
  	unsigned int len = t->len;
  	int ret;
  
  	if (hw->tlen == 0) {
  		/* First byte (I2C command) is chip select */
  		hw->buffer[0] = 1 << msg->spi->chip_select;
  		hw->tlen = 1;
  		hw->rindex = 0;
  	}
  	/*
  	 * We can not immediately send data to the chip, since each I2C message
  	 * resembles a full SPI message (from CS active to CS inactive).
  	 * Enqueue messages up to the first read or until do_transfer is true.
  	 */
  	if (t->tx_buf) {
  		memcpy(&hw->buffer[hw->tlen], t->tx_buf, len);
  		hw->tlen += len;
  		if (t->rx_buf)
  			do_transfer = true;
  		else
  			hw->rindex = hw->tlen - 1;
  	} else if (t->rx_buf) {
  		/*
  		 * For receive-only transfers we still need to perform a dummy
  		 * write to receive data from the SPI chip.
  		 * Read data starts at the end of transmit data (minus 1 to
  		 * account for CS).
  		 */
  		hw->rindex = hw->tlen - 1;
  		memset(&hw->buffer[hw->tlen], 0, len);
  		hw->tlen += len;
  		do_transfer = true;
  	}
  
  	if (do_transfer && hw->tlen > 1) {
  		ret = sc18is602_wait_ready(hw, SC18IS602_BUFSIZ);
  		if (ret < 0)
  			return ret;
  		ret = i2c_master_send(hw->client, hw->buffer, hw->tlen);
  		if (ret < 0)
  			return ret;
  		if (ret != hw->tlen)
  			return -EIO;
  
  		if (t->rx_buf) {
  			int rlen = hw->rindex + len;
  
  			ret = sc18is602_wait_ready(hw, hw->tlen);
  			if (ret < 0)
  				return ret;
  			ret = i2c_master_recv(hw->client, hw->buffer, rlen);
  			if (ret < 0)
  				return ret;
  			if (ret != rlen)
  				return -EIO;
  			memcpy(t->rx_buf, &hw->buffer[hw->rindex], len);
  		}
  		hw->tlen = 0;
  	}
  	return len;
  }
  
  static int sc18is602_setup_transfer(struct sc18is602 *hw, u32 hz, u8 mode)
  {
  	u8 ctrl = 0;
  	int ret;
  
  	if (mode & SPI_CPHA)
  		ctrl |= SC18IS602_MODE_CPHA;
  	if (mode & SPI_CPOL)
  		ctrl |= SC18IS602_MODE_CPOL;
  	if (mode & SPI_LSB_FIRST)
  		ctrl |= SC18IS602_MODE_LSB_FIRST;
  
  	/* Find the closest clock speed */
  	if (hz >= hw->freq / 4) {
  		ctrl |= SC18IS602_MODE_CLOCK_DIV_4;
  		hw->speed = hw->freq / 4;
  	} else if (hz >= hw->freq / 16) {
  		ctrl |= SC18IS602_MODE_CLOCK_DIV_16;
  		hw->speed = hw->freq / 16;
  	} else if (hz >= hw->freq / 64) {
  		ctrl |= SC18IS602_MODE_CLOCK_DIV_64;
  		hw->speed = hw->freq / 64;
  	} else {
  		ctrl |= SC18IS602_MODE_CLOCK_DIV_128;
  		hw->speed = hw->freq / 128;
  	}
  
  	/*
  	 * Don't do anything if the control value did not change. The initial
  	 * value of 0xff for hw->ctrl ensures that the correct mode will be set
  	 * with the first call to this function.
  	 */
  	if (ctrl == hw->ctrl)
  		return 0;
  
  	ret = i2c_smbus_write_byte_data(hw->client, 0xf0, ctrl);
  	if (ret < 0)
  		return ret;
  
  	hw->ctrl = ctrl;
  
  	return 0;
  }
  
  static int sc18is602_check_transfer(struct spi_device *spi,
  				    struct spi_transfer *t, int tlen)
  {

  	if (t && t->len + tlen > SC18IS602_BUFSIZ)
  		return -EINVAL;

  	return 0;
  }
  
  static int sc18is602_transfer_one(struct spi_master *master,
  				  struct spi_message *m)
  {
  	struct sc18is602 *hw = spi_master_get_devdata(master);
  	struct spi_device *spi = m->spi;
  	struct spi_transfer *t;
  	int status = 0;

  	hw->tlen = 0;
  	list_for_each_entry(t, &m->transfers, transfer_list) {

  		bool do_transfer;
  
  		status = sc18is602_check_transfer(spi, t, hw->tlen);
  		if (status < 0)
  			break;

  		status = sc18is602_setup_transfer(hw, t->speed_hz, spi->mode);

  		if (status < 0)
  			break;
  
  		do_transfer = t->cs_change || list_is_last(&t->transfer_list,
  							   &m->transfers);
  
  		if (t->len) {
  			status = sc18is602_txrx(hw, m, t, do_transfer);
  			if (status < 0)
  				break;
  			m->actual_length += status;
  		}
  		status = 0;
  
  		if (t->delay_usecs)
  			udelay(t->delay_usecs);
  	}

  	m->status = status;
  	spi_finalize_current_message(master);
  
  	return status;
  }

  static int sc18is602_setup(struct spi_device *spi)
  {
  	struct sc18is602 *hw = spi_master_get_devdata(spi->master);
  
  	/* SC18IS602 does not support CS2 */
  	if (hw->id == sc18is602 && spi->chip_select == 2)
  		return -ENXIO;
  
  	return 0;
  }

  static int sc18is602_probe(struct i2c_client *client,
  			   const struct i2c_device_id *id)
  {
  	struct device *dev = &client->dev;
  	struct device_node *np = dev->of_node;
  	struct sc18is602_platform_data *pdata = dev_get_platdata(dev);
  	struct sc18is602 *hw;
  	struct spi_master *master;
  	int error;
  
  	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
  				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA))

  		return -EINVAL;

  
  	master = spi_alloc_master(dev, sizeof(struct sc18is602));
  	if (!master)
  		return -ENOMEM;
  
  	hw = spi_master_get_devdata(master);
  	i2c_set_clientdata(client, hw);

  	/* assert reset and then release */
  	hw->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
  	if (IS_ERR(hw->reset))
  		return PTR_ERR(hw->reset);

  	gpiod_set_value_cansleep(hw->reset, 0);

  	hw->master = master;
  	hw->client = client;
  	hw->dev = dev;
  	hw->ctrl = 0xff;

  	if (client->dev.of_node)
  		hw->id = (enum chips)of_device_get_match_data(&client->dev);
  	else
  		hw->id = id->driver_data;

  
  	switch (hw->id) {
  	case sc18is602:
  	case sc18is602b:
  		master->num_chipselect = 4;
  		hw->freq = SC18IS602_CLOCK;
  		break;
  	case sc18is603:
  		master->num_chipselect = 2;
  		if (pdata) {
  			hw->freq = pdata->clock_frequency;
  		} else {
  			const __be32 *val;
  			int len;
  
  			val = of_get_property(np, "clock-frequency", &len);
  			if (val && len >= sizeof(__be32))
  				hw->freq = be32_to_cpup(val);
  		}
  		if (!hw->freq)
  			hw->freq = SC18IS602_CLOCK;
  		break;
  	}

  	master->bus_num = np ? -1 : client->adapter->nr;

  	master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST;

  	master->bits_per_word_mask = SPI_BPW_MASK(8);

  	master->setup = sc18is602_setup;

  	master->transfer_one_message = sc18is602_transfer_one;
  	master->dev.of_node = np;

  	master->min_speed_hz = hw->freq / 128;
  	master->max_speed_hz = hw->freq / 4;

  	error = devm_spi_register_master(dev, master);

  	if (error)
  		goto error_reg;
  
  	return 0;
  
  error_reg:
  	spi_master_put(master);
  	return error;
  }

  static const struct i2c_device_id sc18is602_id[] = {
  	{ "sc18is602", sc18is602 },
  	{ "sc18is602b", sc18is602b },
  	{ "sc18is603", sc18is603 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, sc18is602_id);

  static const struct of_device_id sc18is602_of_match[] = {
  	{
  		.compatible = "nxp,sc18is602",
  		.data = (void *)sc18is602
  	},
  	{
  		.compatible = "nxp,sc18is602b",
  		.data = (void *)sc18is602b
  	},
  	{
  		.compatible = "nxp,sc18is603",
  		.data = (void *)sc18is603
  	},
  	{ },
  };
  MODULE_DEVICE_TABLE(of, sc18is602_of_match);

  static struct i2c_driver sc18is602_driver = {
  	.driver = {
  		.name = "sc18is602",

  		.of_match_table = of_match_ptr(sc18is602_of_match),

  	},
  	.probe = sc18is602_probe,

  	.id_table = sc18is602_id,
  };
  
  module_i2c_driver(sc18is602_driver);
  
  MODULE_DESCRIPTION("SC18IC602/603 SPI Master Driver");
  MODULE_AUTHOR("Guenter Roeck");
  MODULE_LICENSE("GPL");