/*
 * Driver for Atmel QSPI Controller
 *
 * Copyright (C) 2015 Atmel Corporation
 * Copyright (C) 2018 Cryptera A/S
 *
 * Author: Cyrille Pitchen <cyrille.pitchen@atmel.com>
 * Author: Piotr Bugalski <bugalski.piotr@gmail.com>
 *
 * 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.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * This driver is based on drivers/mtd/spi-nor/fsl-quadspi.c from Freescale.
 */

#include <linux/kernel.h>
#include <linux/clk.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/of.h>

#include <linux/io.h>
#include <linux/spi/spi-mem.h>

/* QSPI register offsets */
#define QSPI_CR      0x0000  /* Control Register */
#define QSPI_MR      0x0004  /* Mode Register */
#define QSPI_RD      0x0008  /* Receive Data Register */
#define QSPI_TD      0x000c  /* Transmit Data Register */
#define QSPI_SR      0x0010  /* Status Register */
#define QSPI_IER     0x0014  /* Interrupt Enable Register */
#define QSPI_IDR     0x0018  /* Interrupt Disable Register */
#define QSPI_IMR     0x001c  /* Interrupt Mask Register */
#define QSPI_SCR     0x0020  /* Serial Clock Register */

#define QSPI_IAR     0x0030  /* Instruction Address Register */
#define QSPI_ICR     0x0034  /* Instruction Code Register */
#define QSPI_IFR     0x0038  /* Instruction Frame Register */

#define QSPI_SMR     0x0040  /* Scrambling Mode Register */
#define QSPI_SKR     0x0044  /* Scrambling Key Register */

#define QSPI_WPMR    0x00E4  /* Write Protection Mode Register */
#define QSPI_WPSR    0x00E8  /* Write Protection Status Register */

#define QSPI_VERSION 0x00FC  /* Version Register */


/* Bitfields in QSPI_CR (Control Register) */
#define QSPI_CR_QSPIEN                  BIT(0)
#define QSPI_CR_QSPIDIS                 BIT(1)
#define QSPI_CR_SWRST                   BIT(7)
#define QSPI_CR_LASTXFER                BIT(24)

/* Bitfields in QSPI_MR (Mode Register) */
#define QSPI_MR_SMM                     BIT(0)
#define QSPI_MR_LLB                     BIT(1)
#define QSPI_MR_WDRBT                   BIT(2)
#define QSPI_MR_SMRM                    BIT(3)
#define QSPI_MR_CSMODE_MASK             GENMASK(5, 4)
#define QSPI_MR_CSMODE_NOT_RELOADED     (0 << 4)
#define QSPI_MR_CSMODE_LASTXFER         (1 << 4)
#define QSPI_MR_CSMODE_SYSTEMATICALLY   (2 << 4)
#define QSPI_MR_NBBITS_MASK             GENMASK(11, 8)
#define QSPI_MR_NBBITS(n)               ((((n) - 8) << 8) & QSPI_MR_NBBITS_MASK)
#define QSPI_MR_DLYBCT_MASK             GENMASK(23, 16)
#define QSPI_MR_DLYBCT(n)               (((n) << 16) & QSPI_MR_DLYBCT_MASK)
#define QSPI_MR_DLYCS_MASK              GENMASK(31, 24)
#define QSPI_MR_DLYCS(n)                (((n) << 24) & QSPI_MR_DLYCS_MASK)

/* Bitfields in QSPI_SR/QSPI_IER/QSPI_IDR/QSPI_IMR  */
#define QSPI_SR_RDRF                    BIT(0)
#define QSPI_SR_TDRE                    BIT(1)
#define QSPI_SR_TXEMPTY                 BIT(2)
#define QSPI_SR_OVRES                   BIT(3)
#define QSPI_SR_CSR                     BIT(8)
#define QSPI_SR_CSS                     BIT(9)
#define QSPI_SR_INSTRE                  BIT(10)
#define QSPI_SR_QSPIENS                 BIT(24)

#define QSPI_SR_CMD_COMPLETED	(QSPI_SR_INSTRE | QSPI_SR_CSR)

/* Bitfields in QSPI_SCR (Serial Clock Register) */
#define QSPI_SCR_CPOL                   BIT(0)
#define QSPI_SCR_CPHA                   BIT(1)
#define QSPI_SCR_SCBR_MASK              GENMASK(15, 8)
#define QSPI_SCR_SCBR(n)                (((n) << 8) & QSPI_SCR_SCBR_MASK)
#define QSPI_SCR_DLYBS_MASK             GENMASK(23, 16)
#define QSPI_SCR_DLYBS(n)               (((n) << 16) & QSPI_SCR_DLYBS_MASK)

/* Bitfields in QSPI_ICR (Instruction Code Register) */
#define QSPI_ICR_INST_MASK              GENMASK(7, 0)
#define QSPI_ICR_INST(inst)             (((inst) << 0) & QSPI_ICR_INST_MASK)
#define QSPI_ICR_OPT_MASK               GENMASK(23, 16)
#define QSPI_ICR_OPT(opt)               (((opt) << 16) & QSPI_ICR_OPT_MASK)

/* Bitfields in QSPI_IFR (Instruction Frame Register) */
#define QSPI_IFR_WIDTH_MASK             GENMASK(2, 0)
#define QSPI_IFR_WIDTH_SINGLE_BIT_SPI   (0 << 0)
#define QSPI_IFR_WIDTH_DUAL_OUTPUT      (1 << 0)
#define QSPI_IFR_WIDTH_QUAD_OUTPUT      (2 << 0)
#define QSPI_IFR_WIDTH_DUAL_IO          (3 << 0)
#define QSPI_IFR_WIDTH_QUAD_IO          (4 << 0)
#define QSPI_IFR_WIDTH_DUAL_CMD         (5 << 0)
#define QSPI_IFR_WIDTH_QUAD_CMD         (6 << 0)
#define QSPI_IFR_INSTEN                 BIT(4)
#define QSPI_IFR_ADDREN                 BIT(5)
#define QSPI_IFR_OPTEN                  BIT(6)
#define QSPI_IFR_DATAEN                 BIT(7)
#define QSPI_IFR_OPTL_MASK              GENMASK(9, 8)
#define QSPI_IFR_OPTL_1BIT              (0 << 8)
#define QSPI_IFR_OPTL_2BIT              (1 << 8)
#define QSPI_IFR_OPTL_4BIT              (2 << 8)
#define QSPI_IFR_OPTL_8BIT              (3 << 8)
#define QSPI_IFR_ADDRL                  BIT(10)
#define QSPI_IFR_TFRTYP_MASK            GENMASK(13, 12)
#define QSPI_IFR_TFRTYP_TRSFR_READ      (0 << 12)
#define QSPI_IFR_TFRTYP_TRSFR_READ_MEM  (1 << 12)
#define QSPI_IFR_TFRTYP_TRSFR_WRITE     (2 << 12)
#define QSPI_IFR_TFRTYP_TRSFR_WRITE_MEM (3 << 13)
#define QSPI_IFR_CRM                    BIT(14)
#define QSPI_IFR_NBDUM_MASK             GENMASK(20, 16)
#define QSPI_IFR_NBDUM(n)               (((n) << 16) & QSPI_IFR_NBDUM_MASK)

/* Bitfields in QSPI_SMR (Scrambling Mode Register) */
#define QSPI_SMR_SCREN                  BIT(0)
#define QSPI_SMR_RVDIS                  BIT(1)

/* Bitfields in QSPI_WPMR (Write Protection Mode Register) */
#define QSPI_WPMR_WPEN                  BIT(0)
#define QSPI_WPMR_WPKEY_MASK            GENMASK(31, 8)
#define QSPI_WPMR_WPKEY(wpkey)          (((wpkey) << 8) & QSPI_WPMR_WPKEY_MASK)

/* Bitfields in QSPI_WPSR (Write Protection Status Register) */
#define QSPI_WPSR_WPVS                  BIT(0)
#define QSPI_WPSR_WPVSRC_MASK           GENMASK(15, 8)
#define QSPI_WPSR_WPVSRC(src)           (((src) << 8) & QSPI_WPSR_WPVSRC)


struct atmel_qspi {
	void __iomem		*regs;
	void __iomem		*mem;
	struct clk		*clk;
	struct platform_device	*pdev;
	u32			pending;
	struct completion	cmd_completion;
};

struct qspi_mode {
	u8 cmd_buswidth;
	u8 addr_buswidth;
	u8 data_buswidth;
	u32 config;
};

static const struct qspi_mode sama5d2_qspi_modes[] = {
	{ 1, 1, 1, QSPI_IFR_WIDTH_SINGLE_BIT_SPI },
	{ 1, 1, 2, QSPI_IFR_WIDTH_DUAL_OUTPUT },
	{ 1, 1, 4, QSPI_IFR_WIDTH_QUAD_OUTPUT },
	{ 1, 2, 2, QSPI_IFR_WIDTH_DUAL_IO },
	{ 1, 4, 4, QSPI_IFR_WIDTH_QUAD_IO },
	{ 2, 2, 2, QSPI_IFR_WIDTH_DUAL_CMD },
	{ 4, 4, 4, QSPI_IFR_WIDTH_QUAD_CMD },
};

/* Register access functions */
static inline u32 qspi_readl(struct atmel_qspi *aq, u32 reg)
{
	return readl_relaxed(aq->regs + reg);
}

static inline void qspi_writel(struct atmel_qspi *aq, u32 reg, u32 value)
{
	writel_relaxed(value, aq->regs + reg);
}

static inline bool is_compatible(const struct spi_mem_op *op,
				 const struct qspi_mode *mode)
{
	if (op->cmd.buswidth != mode->cmd_buswidth)
		return false;

	if (op->addr.nbytes && op->addr.buswidth != mode->addr_buswidth)
		return false;

	if (op->data.nbytes && op->data.buswidth != mode->data_buswidth)
		return false;

	return true;
}

static int find_mode(const struct spi_mem_op *op)
{
	u32 i;

	for (i = 0; i < ARRAY_SIZE(sama5d2_qspi_modes); i++)
		if (is_compatible(op, &sama5d2_qspi_modes[i]))
			return i;

	return -1;
}

static bool atmel_qspi_supports_op(struct spi_mem *mem,
				   const struct spi_mem_op *op)
{
	if (find_mode(op) < 0)
		return false;

	/* special case not supported by hardware */
	if (op->addr.nbytes == 2 && op->cmd.buswidth != op->addr.buswidth &&
		op->dummy.nbytes == 0)
		return false;

	return true;
}

static int atmel_qspi_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
{
	struct atmel_qspi *aq = spi_controller_get_devdata(mem->spi->master);
	int mode;
	u32 dummy_cycles = 0;
	u32 iar, icr, ifr, sr;
	int err = 0;

	iar = 0;
	icr = QSPI_ICR_INST(op->cmd.opcode);
	ifr = QSPI_IFR_INSTEN;

	qspi_writel(aq, QSPI_MR, QSPI_MR_SMM);

	mode = find_mode(op);
	if (mode < 0)
		return -ENOTSUPP;

	ifr |= sama5d2_qspi_modes[mode].config;

	if (op->dummy.buswidth && op->dummy.nbytes)
		dummy_cycles = op->dummy.nbytes * 8 / op->dummy.buswidth;

	if (op->addr.buswidth) {
		switch (op->addr.nbytes) {
		case 0:
			break;
		case 1:
			ifr |= QSPI_IFR_OPTEN | QSPI_IFR_OPTL_8BIT;
			icr |= QSPI_ICR_OPT(op->addr.val & 0xff);
			break;
		case 2:
			if (dummy_cycles < 8 / op->addr.buswidth) {
				ifr &= ~QSPI_IFR_INSTEN;
				ifr |= QSPI_IFR_ADDREN;
				iar = (op->cmd.opcode << 16) |
					(op->addr.val & 0xffff);
			} else {
				ifr |= QSPI_IFR_ADDREN;
				iar = (op->addr.val << 8) & 0xffffff;
				dummy_cycles -= 8 / op->addr.buswidth;
			}
			break;
		case 3:
			ifr |= QSPI_IFR_ADDREN;
			iar = op->addr.val & 0xffffff;
			break;
		case 4:
			ifr |= QSPI_IFR_ADDREN | QSPI_IFR_ADDRL;
			iar = op->addr.val & 0x7ffffff;
			break;
		default:
			return -ENOTSUPP;
		}
	}

	/* Set number of dummy cycles */
	if (dummy_cycles)
		ifr |= QSPI_IFR_NBDUM(dummy_cycles);

	/* Set data enable */
	if (op->data.nbytes)
		ifr |= QSPI_IFR_DATAEN;

	if (op->data.dir == SPI_MEM_DATA_IN && op->data.nbytes)
		ifr |= QSPI_IFR_TFRTYP_TRSFR_READ;
	else
		ifr |= QSPI_IFR_TFRTYP_TRSFR_WRITE;

	/* Clear pending interrupts */
	(void)qspi_readl(aq, QSPI_SR);

	/* Set QSPI Instruction Frame registers */
	qspi_writel(aq, QSPI_IAR, iar);
	qspi_writel(aq, QSPI_ICR, icr);
	qspi_writel(aq, QSPI_IFR, ifr);

	/* Skip to the final steps if there is no data */
	if (op->data.nbytes) {
		/* Dummy read of QSPI_IFR to synchronize APB and AHB accesses */
		(void)qspi_readl(aq, QSPI_IFR);

		/* Send/Receive data */
		if (op->data.dir == SPI_MEM_DATA_IN)
			_memcpy_fromio(op->data.buf.in,
				aq->mem + iar, op->data.nbytes);
		else
			_memcpy_toio(aq->mem + iar,
				op->data.buf.out, op->data.nbytes);

		/* Release the chip-select */
		qspi_writel(aq, QSPI_CR, QSPI_CR_LASTXFER);
	}

	/* Poll INSTRuction End status */
	sr = qspi_readl(aq, QSPI_SR);
	if ((sr & QSPI_SR_CMD_COMPLETED) == QSPI_SR_CMD_COMPLETED)
		return err;

	/* Wait for INSTRuction End interrupt */
	reinit_completion(&aq->cmd_completion);
	aq->pending = sr & QSPI_SR_CMD_COMPLETED;
	qspi_writel(aq, QSPI_IER, QSPI_SR_CMD_COMPLETED);
	if (!wait_for_completion_timeout(&aq->cmd_completion,
					 msecs_to_jiffies(1000)))
		err = -ETIMEDOUT;
	qspi_writel(aq, QSPI_IDR, QSPI_SR_CMD_COMPLETED);

	return err;
}

const char *atmel_qspi_get_name(struct spi_mem *spimem)
{
	return dev_name(spimem->spi->dev.parent);
}

static const struct spi_controller_mem_ops atmel_qspi_mem_ops = {
	.supports_op = atmel_qspi_supports_op,
	.exec_op = atmel_qspi_exec_op,
	.get_name = atmel_qspi_get_name
};

static int atmel_qspi_setup(struct spi_device *spi)
{
	struct spi_controller *ctrl = spi->master;
	struct atmel_qspi *aq = spi_controller_get_devdata(ctrl);
	unsigned long src_rate;
	u32 scr, scbr;

	if (ctrl->busy)
		return -EBUSY;

	if (!spi->max_speed_hz)
		return -EINVAL;

	src_rate = clk_get_rate(aq->clk);
	if (!src_rate)
		return -EINVAL;

	/* Compute the QSPI baudrate */
	scbr = DIV_ROUND_UP(src_rate, spi->max_speed_hz);
	if (scbr > 0)
		scbr--;

	scr = QSPI_SCR_SCBR(scbr);
	qspi_writel(aq, QSPI_SCR, scr);

	return 0;
}

static int atmel_qspi_init(struct atmel_qspi *aq)
{
	/* Reset the QSPI controller */
	qspi_writel(aq, QSPI_CR, QSPI_CR_SWRST);

	/* Enable the QSPI controller */
	qspi_writel(aq, QSPI_CR, QSPI_CR_QSPIEN);

	return 0;
}

static irqreturn_t atmel_qspi_interrupt(int irq, void *dev_id)
{
	struct atmel_qspi *aq = (struct atmel_qspi *)dev_id;
	u32 status, mask, pending;

	status = qspi_readl(aq, QSPI_SR);
	mask = qspi_readl(aq, QSPI_IMR);
	pending = status & mask;

	if (!pending)
		return IRQ_NONE;

	aq->pending |= pending;
	if ((aq->pending & QSPI_SR_CMD_COMPLETED) == QSPI_SR_CMD_COMPLETED)
		complete(&aq->cmd_completion);

	return IRQ_HANDLED;
}

static int atmel_qspi_probe(struct platform_device *pdev)
{
	struct spi_controller *ctrl;
	struct atmel_qspi *aq;
	struct resource *res;
	int irq, err = 0;

	ctrl = spi_alloc_master(&pdev->dev, sizeof(*aq));
	if (!ctrl)
		return -ENOMEM;

	ctrl->mode_bits = SPI_RX_DUAL | SPI_RX_QUAD | SPI_TX_DUAL | SPI_TX_QUAD;
	ctrl->setup = atmel_qspi_setup;
	ctrl->bus_num = -1;
	ctrl->mem_ops = &atmel_qspi_mem_ops;
	ctrl->num_chipselect = 1;
	ctrl->dev.of_node = pdev->dev.of_node;
	platform_set_drvdata(pdev, ctrl);

	aq = spi_controller_get_devdata(ctrl);

	init_completion(&aq->cmd_completion);
	aq->pdev = pdev;

	/* Map the registers */
	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "qspi_base");
	aq->regs = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(aq->regs)) {
		dev_err(&pdev->dev, "missing registers\n");
		err = PTR_ERR(aq->regs);
		goto exit;
	}

	/* Map the AHB memory */
	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "qspi_mmap");
	aq->mem = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(aq->mem)) {
		dev_err(&pdev->dev, "missing AHB memory\n");
		err = PTR_ERR(aq->mem);
		goto exit;
	}

	/* Get the peripheral clock */
	aq->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(aq->clk)) {
		dev_err(&pdev->dev, "missing peripheral clock\n");
		err = PTR_ERR(aq->clk);
		goto exit;
	}

	/* Enable the peripheral clock */
	err = clk_prepare_enable(aq->clk);
	if (err) {
		dev_err(&pdev->dev, "failed to enable the peripheral clock\n");
		goto exit;
	}

	/* Request the IRQ */
	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
		dev_err(&pdev->dev, "missing IRQ\n");
		err = irq;
		goto disable_clk;
	}
	err = devm_request_irq(&pdev->dev, irq, atmel_qspi_interrupt,
			       0, dev_name(&pdev->dev), aq);
	if (err)
		goto disable_clk;

	err = atmel_qspi_init(aq);
	if (err)
		goto disable_clk;

	err = spi_register_controller(ctrl);
	if (err)
		goto disable_clk;

	return 0;

disable_clk:
	clk_disable_unprepare(aq->clk);
exit:
	spi_controller_put(ctrl);

	return err;
}

static int atmel_qspi_remove(struct platform_device *pdev)
{
	struct spi_controller *ctrl = platform_get_drvdata(pdev);
	struct atmel_qspi *aq = spi_controller_get_devdata(ctrl);

	spi_unregister_controller(ctrl);
	qspi_writel(aq, QSPI_CR, QSPI_CR_QSPIDIS);
	clk_disable_unprepare(aq->clk);
	return 0;
}

static int __maybe_unused atmel_qspi_suspend(struct device *dev)
{
	struct atmel_qspi *aq = dev_get_drvdata(dev);

	clk_disable_unprepare(aq->clk);

	return 0;
}

static int __maybe_unused atmel_qspi_resume(struct device *dev)
{
	struct atmel_qspi *aq = dev_get_drvdata(dev);

	clk_prepare_enable(aq->clk);

	return atmel_qspi_init(aq);
}

static SIMPLE_DEV_PM_OPS(atmel_qspi_pm_ops, atmel_qspi_suspend,
			 atmel_qspi_resume);

static const struct of_device_id atmel_qspi_dt_ids[] = {
	{ .compatible = "atmel,sama5d2-qspi" },
	{ /* sentinel */ }
};

MODULE_DEVICE_TABLE(of, atmel_qspi_dt_ids);

static struct platform_driver atmel_qspi_driver = {
	.driver = {
		.name	= "atmel_qspi",
		.of_match_table	= atmel_qspi_dt_ids,
		.pm	= &atmel_qspi_pm_ops,
	},
	.probe		= atmel_qspi_probe,
	.remove		= atmel_qspi_remove,
};
module_platform_driver(atmel_qspi_driver);

MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@atmel.com>");
MODULE_AUTHOR("Piotr Bugalski <bugalski.piotr@gmail.com");
MODULE_DESCRIPTION("Atmel QSPI Controller driver");
MODULE_LICENSE("GPL v2");