/*
   * 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/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/module.h>
  #include <linux/pm_runtime.h>
  #include <linux/of.h>
  #include <linux/of_device.h>
  #include <linux/clk.h>
  #include <linux/sizes.h>
  #include <asm/unaligned.h>
  
  #define DRIVER_NAME			"orion_spi"
  
  /* Runtime PM autosuspend timeout: PM is fairly light on this driver */
  #define SPI_AUTOSUSPEND_TIMEOUT		200
  
  /* Some SoCs using this driver support up to 8 chip selects.
   * It is up to the implementer to only use the chip selects
   * that are available.
   */
  #define ORION_NUM_CHIPSELECTS		8
  
  #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_TIMING_PARAMS_REG	0x18
  
  #define ORION_SPI_TMISO_SAMPLE_MASK	(0x3 << 6)
  #define ORION_SPI_TMISO_SAMPLE_1	(1 << 6)
  #define ORION_SPI_TMISO_SAMPLE_2	(2 << 6)
  
  #define ORION_SPI_MODE_CPOL		(1 << 11)
  #define ORION_SPI_MODE_CPHA		(1 << 12)
  #define ORION_SPI_IF_8_16_BIT_MODE	(1 << 5)
  #define ORION_SPI_CLK_PRESCALE_MASK	0x1F
  #define ARMADA_SPI_CLK_PRESCALE_MASK	0xDF
  #define ORION_SPI_MODE_MASK		(ORION_SPI_MODE_CPOL | \
  					 ORION_SPI_MODE_CPHA)
  #define ORION_SPI_CS_MASK	0x1C
  #define ORION_SPI_CS_SHIFT	2
  #define ORION_SPI_CS(cs)	((cs << ORION_SPI_CS_SHIFT) & \
  					ORION_SPI_CS_MASK)
  
  enum orion_spi_type {
  	ORION_SPI,
  	ARMADA_SPI,
  };
  
  struct orion_spi_dev {
  	enum orion_spi_type	typ;
  	/*
  	 * min_divisor and max_hz should be exclusive, the only we can
  	 * have both is for managing the armada-370-spi case with old
  	 * device tree
  	 */
  	unsigned long		max_hz;
  	unsigned int		min_divisor;
  	unsigned int		max_divisor;
  	u32			prescale_mask;
  	bool			is_errata_50mhz_ac;
  };
  
  struct orion_spi {
  	struct spi_master	*master;
  	void __iomem		*base;
  	struct clk              *clk;
  	const struct orion_spi_dev *devdata;
  };
  
  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_baudrate_set(struct spi_device *spi, unsigned int speed)
  {
  	u32 tclk_hz;
  	u32 rate;
  	u32 prescale;
  	u32 reg;
  	struct orion_spi *orion_spi;
  	const struct orion_spi_dev *devdata;
  
  	orion_spi = spi_master_get_devdata(spi->master);
  	devdata = orion_spi->devdata;
  
  	tclk_hz = clk_get_rate(orion_spi->clk);
  
  	if (devdata->typ == ARMADA_SPI) {
  		unsigned int clk, spr, sppr, sppr2, err;
  		unsigned int best_spr, best_sppr, best_err;
  
  		best_err = speed;
  		best_spr = 0;
  		best_sppr = 0;
  
  		/* Iterate over the valid range looking for best fit */
  		for (sppr = 0; sppr < 8; sppr++) {
  			sppr2 = 0x1 << sppr;
  
  			spr = tclk_hz / sppr2;
  			spr = DIV_ROUND_UP(spr, speed);
  			if ((spr == 0) || (spr > 15))
  				continue;
  
  			clk = tclk_hz / (spr * sppr2);
  			err = speed - clk;
  
  			if (err < best_err) {
  				best_spr = spr;
  				best_sppr = sppr;
  				best_err = err;
  			}
  		}
  
  		if ((best_sppr == 0) && (best_spr == 0))
  			return -EINVAL;
  
  		prescale = ((best_sppr & 0x6) << 5) |
  			((best_sppr & 0x1) << 4) | best_spr;
  	} else {
  		/*
  		 * 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 & ~devdata->prescale_mask) | prescale);
  	writel(reg, spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
  
  	return 0;
  }
  
  static void
  orion_spi_mode_set(struct spi_device *spi)
  {
  	u32 reg;
  	struct orion_spi *orion_spi;
  
  	orion_spi = spi_master_get_devdata(spi->master);
  
  	reg = readl(spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
  	reg &= ~ORION_SPI_MODE_MASK;
  	if (spi->mode & SPI_CPOL)
  		reg |= ORION_SPI_MODE_CPOL;
  	if (spi->mode & SPI_CPHA)
  		reg |= ORION_SPI_MODE_CPHA;
  	writel(reg, spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
  }
  
  static void
  orion_spi_50mhz_ac_timing_erratum(struct spi_device *spi, unsigned int speed)
  {
  	u32 reg;
  	struct orion_spi *orion_spi;
  
  	orion_spi = spi_master_get_devdata(spi->master);
  
  	/*
  	 * Erratum description: (Erratum NO. FE-9144572) The device
  	 * SPI interface supports frequencies of up to 50 MHz.
  	 * However, due to this erratum, when the device core clock is
  	 * 250 MHz and the SPI interfaces is configured for 50MHz SPI
  	 * clock and CPOL=CPHA=1 there might occur data corruption on
  	 * reads from the SPI device.
  	 * Erratum Workaround:
  	 * Work in one of the following configurations:
  	 * 1. Set CPOL=CPHA=0 in "SPI Interface Configuration
  	 * Register".
  	 * 2. Set TMISO_SAMPLE value to 0x2 in "SPI Timing Parameters 1
  	 * Register" before setting the interface.
  	 */
  	reg = readl(spi_reg(orion_spi, ORION_SPI_TIMING_PARAMS_REG));
  	reg &= ~ORION_SPI_TMISO_SAMPLE_MASK;
  
  	if (clk_get_rate(orion_spi->clk) == 250000000 &&
  			speed == 50000000 && spi->mode & SPI_CPOL &&
  			spi->mode & SPI_CPHA)
  		reg |= ORION_SPI_TMISO_SAMPLE_2;
  	else
  		reg |= ORION_SPI_TMISO_SAMPLE_1; /* This is the default value */
  
  	writel(reg, spi_reg(orion_spi, ORION_SPI_TIMING_PARAMS_REG));
  }
  
  /*
   * 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;
  
  	orion_spi_mode_set(spi);
  
  	if (orion_spi->devdata->is_errata_50mhz_ac)
  		orion_spi_50mhz_ac_timing_erratum(spi, speed);
  
  	rc = orion_spi_baudrate_set(spi, speed);
  	if (rc)
  		return rc;
  
  	if (bits_per_word == 16)
  		orion_spi_setbits(orion_spi, ORION_SPI_IF_CONFIG_REG,
  				  ORION_SPI_IF_8_16_BIT_MODE);
  	else
  		orion_spi_clrbits(orion_spi, ORION_SPI_IF_CONFIG_REG,
  				  ORION_SPI_IF_8_16_BIT_MODE);
  
  	return 0;
  }
  
  static void orion_spi_set_cs(struct spi_device *spi, bool enable)
  {
  	struct orion_spi *orion_spi;
  
  	orion_spi = spi_master_get_devdata(spi->master);
  
  	orion_spi_clrbits(orion_spi, ORION_SPI_IF_CTRL_REG, ORION_SPI_CS_MASK);
  	orion_spi_setbits(orion_spi, ORION_SPI_IF_CTRL_REG,
  				ORION_SPI_CS(spi->chip_select));
  
  	/* Chip select logic is inverted from spi_set_cs */
  	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;
  
  		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)
  {
  	unsigned int count;
  	int word_len;
  
  	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 int orion_spi_transfer_one(struct spi_master *master,
  					struct spi_device *spi,
  					struct spi_transfer *t)
  {
  	int status = 0;
  
  	status = orion_spi_setup_transfer(spi, t);
  	if (status < 0)
  		return status;
  
  	if (t->len)
  		orion_spi_write_read(spi, t);
  
  	return status;
  }
  
  static int orion_spi_setup(struct spi_device *spi)
  {
  	return orion_spi_setup_transfer(spi, NULL);
  }
  
  static int orion_spi_reset(struct orion_spi *orion_spi)
  {
  	/* Verify that the CS is deasserted */
  	orion_spi_clrbits(orion_spi, ORION_SPI_IF_CTRL_REG, 0x1);
  	return 0;
  }
  
  static const struct orion_spi_dev orion_spi_dev_data = {
  	.typ = ORION_SPI,
  	.min_divisor = 4,
  	.max_divisor = 30,
  	.prescale_mask = ORION_SPI_CLK_PRESCALE_MASK,
  };
  
  static const struct orion_spi_dev armada_370_spi_dev_data = {
  	.typ = ARMADA_SPI,
  	.min_divisor = 4,
  	.max_divisor = 1920,
  	.max_hz = 50000000,
  	.prescale_mask = ARMADA_SPI_CLK_PRESCALE_MASK,
  };
  
  static const struct orion_spi_dev armada_xp_spi_dev_data = {
  	.typ = ARMADA_SPI,
  	.max_hz = 50000000,
  	.max_divisor = 1920,
  	.prescale_mask = ARMADA_SPI_CLK_PRESCALE_MASK,
  };
  
  static const struct orion_spi_dev armada_375_spi_dev_data = {
  	.typ = ARMADA_SPI,
  	.min_divisor = 15,
  	.max_divisor = 1920,
  	.prescale_mask = ARMADA_SPI_CLK_PRESCALE_MASK,
  };
  
  static const struct orion_spi_dev armada_380_spi_dev_data = {
  	.typ = ARMADA_SPI,
  	.max_hz = 50000000,
  	.max_divisor = 1920,
  	.prescale_mask = ARMADA_SPI_CLK_PRESCALE_MASK,
  	.is_errata_50mhz_ac = true,
  };
  
  static const struct of_device_id orion_spi_of_match_table[] = {
  	{
  		.compatible = "marvell,orion-spi",
  		.data = &orion_spi_dev_data,
  	},
  	{
  		.compatible = "marvell,armada-370-spi",
  		.data = &armada_370_spi_dev_data,
  	},
  	{
  		.compatible = "marvell,armada-375-spi",
  		.data = &armada_375_spi_dev_data,
  	},
  	{
  		.compatible = "marvell,armada-380-spi",
  		.data = &armada_380_spi_dev_data,
  	},
  	{
  		.compatible = "marvell,armada-390-spi",
  		.data = &armada_xp_spi_dev_data,
  	},
  	{
  		.compatible = "marvell,armada-xp-spi",
  		.data = &armada_xp_spi_dev_data,
  	},
  
  	{}
  };
  MODULE_DEVICE_TABLE(of, orion_spi_of_match_table);
  
  static int orion_spi_probe(struct platform_device *pdev)
  {
  	const struct of_device_id *of_id;
  	const struct orion_spi_dev *devdata;
  	struct spi_master *master;
  	struct orion_spi *spi;
  	struct resource *r;
  	unsigned long tclk_hz;
  	int status = 0;
  
  	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;
  	if (pdev->dev.of_node) {
  		u32 cell_index;
  
  		if (!of_property_read_u32(pdev->dev.of_node, "cell-index",
  					  &cell_index))
  			master->bus_num = cell_index;
  	}
  
  	/* we support only mode 0, and no options */
  	master->mode_bits = SPI_CPHA | SPI_CPOL;
  	master->set_cs = orion_spi_set_cs;
  	master->transfer_one = orion_spi_transfer_one;
  	master->num_chipselect = ORION_NUM_CHIPSELECTS;
  	master->setup = orion_spi_setup;
  	master->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16);
  	master->auto_runtime_pm = true;
  
  	platform_set_drvdata(pdev, master);
  
  	spi = spi_master_get_devdata(master);
  	spi->master = master;
  
  	of_id = of_match_device(orion_spi_of_match_table, &pdev->dev);
  	devdata = (of_id) ? of_id->data : &orion_spi_dev_data;
  	spi->devdata = devdata;
  
  	spi->clk = devm_clk_get(&pdev->dev, NULL);
  	if (IS_ERR(spi->clk)) {
  		status = PTR_ERR(spi->clk);
  		goto out;
  	}
  
  	status = clk_prepare_enable(spi->clk);
  	if (status)
  		goto out;
  
  	tclk_hz = clk_get_rate(spi->clk);
  
  	/*
  	 * With old device tree, armada-370-spi could be used with
  	 * Armada XP, however for this SoC the maximum frequency is
  	 * 50MHz instead of tclk/4. On Armada 370, tclk cannot be
  	 * higher than 200MHz. So, in order to be able to handle both
  	 * SoCs, we can take the minimum of 50MHz and tclk/4.
  	 */
  	if (of_device_is_compatible(pdev->dev.of_node,
  					"marvell,armada-370-spi"))
  		master->max_speed_hz = min(devdata->max_hz,
  				DIV_ROUND_UP(tclk_hz, devdata->min_divisor));
  	else if (devdata->min_divisor)
  		master->max_speed_hz =
  			DIV_ROUND_UP(tclk_hz, devdata->min_divisor);
  	else
  		master->max_speed_hz = devdata->max_hz;
  	master->min_speed_hz = DIV_ROUND_UP(tclk_hz, devdata->max_divisor);
  
  	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	spi->base = devm_ioremap_resource(&pdev->dev, r);
  	if (IS_ERR(spi->base)) {
  		status = PTR_ERR(spi->base);
  		goto out_rel_clk;
  	}
  
  	pm_runtime_set_active(&pdev->dev);
  	pm_runtime_use_autosuspend(&pdev->dev);
  	pm_runtime_set_autosuspend_delay(&pdev->dev, SPI_AUTOSUSPEND_TIMEOUT);
  	pm_runtime_enable(&pdev->dev);
  
  	status = orion_spi_reset(spi);
  	if (status < 0)
  		goto out_rel_pm;
  
  	pm_runtime_mark_last_busy(&pdev->dev);
  	pm_runtime_put_autosuspend(&pdev->dev);
  
  	master->dev.of_node = pdev->dev.of_node;
  	status = spi_register_master(master);
  	if (status < 0)
  		goto out_rel_pm;
  
  	return status;
  
  out_rel_pm:
  	pm_runtime_disable(&pdev->dev);
  out_rel_clk:
  	clk_disable_unprepare(spi->clk);
  out:
  	spi_master_put(master);
  	return status;
  }
  
  
  static int orion_spi_remove(struct platform_device *pdev)
  {
  	struct spi_master *master = platform_get_drvdata(pdev);
  	struct orion_spi *spi = spi_master_get_devdata(master);
  
  	pm_runtime_get_sync(&pdev->dev);
  	clk_disable_unprepare(spi->clk);
  
  	spi_unregister_master(master);
  	pm_runtime_disable(&pdev->dev);
  
  	return 0;
  }
  
  MODULE_ALIAS("platform:" DRIVER_NAME);
  
  #ifdef CONFIG_PM
  static int orion_spi_runtime_suspend(struct device *dev)
  {
  	struct spi_master *master = dev_get_drvdata(dev);
  	struct orion_spi *spi = spi_master_get_devdata(master);
  
  	clk_disable_unprepare(spi->clk);
  	return 0;
  }
  
  static int orion_spi_runtime_resume(struct device *dev)
  {
  	struct spi_master *master = dev_get_drvdata(dev);
  	struct orion_spi *spi = spi_master_get_devdata(master);
  
  	return clk_prepare_enable(spi->clk);
  }
  #endif
  
  static const struct dev_pm_ops orion_spi_pm_ops = {
  	SET_RUNTIME_PM_OPS(orion_spi_runtime_suspend,
  			   orion_spi_runtime_resume,
  			   NULL)
  };
  
  static struct platform_driver orion_spi_driver = {
  	.driver = {
  		.name	= DRIVER_NAME,
  		.pm	= &orion_spi_pm_ops,
  		.of_match_table = of_match_ptr(orion_spi_of_match_table),
  	},
  	.probe		= orion_spi_probe,
  	.remove		= orion_spi_remove,
  };
  
  module_platform_driver(orion_spi_driver);
  
  MODULE_DESCRIPTION("Orion SPI driver");
  MODULE_AUTHOR("Shadi Ammouri <shadi@marvell.com>");
  MODULE_LICENSE("GPL");