/*
 * HiSilicon SPI Nor Flash Controller Driver
 *
 * Copyright (c) 2015-2016 HiSilicon Technologies Co., Ltd.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/dma-mapping.h>
#include <linux/iopoll.h>
#include <linux/module.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/spi-nor.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

/* Hardware register offsets and field definitions */
#define FMC_CFG				0x00
#define FMC_CFG_OP_MODE_MASK		BIT_MASK(0)
#define FMC_CFG_OP_MODE_BOOT		0
#define FMC_CFG_OP_MODE_NORMAL		1
#define FMC_CFG_FLASH_SEL(type)		(((type) & 0x3) << 1)
#define FMC_CFG_FLASH_SEL_MASK		0x6
#define FMC_ECC_TYPE(type)		(((type) & 0x7) << 5)
#define FMC_ECC_TYPE_MASK		GENMASK(7, 5)
#define SPI_NOR_ADDR_MODE_MASK		BIT_MASK(10)
#define SPI_NOR_ADDR_MODE_3BYTES	(0x0 << 10)
#define SPI_NOR_ADDR_MODE_4BYTES	(0x1 << 10)
#define FMC_GLOBAL_CFG			0x04
#define FMC_GLOBAL_CFG_WP_ENABLE	BIT(6)
#define FMC_SPI_TIMING_CFG		0x08
#define TIMING_CFG_TCSH(nr)		(((nr) & 0xf) << 8)
#define TIMING_CFG_TCSS(nr)		(((nr) & 0xf) << 4)
#define TIMING_CFG_TSHSL(nr)		((nr) & 0xf)
#define CS_HOLD_TIME			0x6
#define CS_SETUP_TIME			0x6
#define CS_DESELECT_TIME		0xf
#define FMC_INT				0x18
#define FMC_INT_OP_DONE			BIT(0)
#define FMC_INT_CLR			0x20
#define FMC_CMD				0x24
#define FMC_CMD_CMD1(cmd)		((cmd) & 0xff)
#define FMC_ADDRL			0x2c
#define FMC_OP_CFG			0x30
#define OP_CFG_FM_CS(cs)		((cs) << 11)
#define OP_CFG_MEM_IF_TYPE(type)	(((type) & 0x7) << 7)
#define OP_CFG_ADDR_NUM(addr)		(((addr) & 0x7) << 4)
#define OP_CFG_DUMMY_NUM(dummy)		((dummy) & 0xf)
#define FMC_DATA_NUM			0x38
#define FMC_DATA_NUM_CNT(cnt)		((cnt) & GENMASK(13, 0))
#define FMC_OP				0x3c
#define FMC_OP_DUMMY_EN			BIT(8)
#define FMC_OP_CMD1_EN			BIT(7)
#define FMC_OP_ADDR_EN			BIT(6)
#define FMC_OP_WRITE_DATA_EN		BIT(5)
#define FMC_OP_READ_DATA_EN		BIT(2)
#define FMC_OP_READ_STATUS_EN		BIT(1)
#define FMC_OP_REG_OP_START		BIT(0)
#define FMC_DMA_LEN			0x40
#define FMC_DMA_LEN_SET(len)		((len) & GENMASK(27, 0))
#define FMC_DMA_SADDR_D0		0x4c
#define HIFMC_DMA_MAX_LEN		(4096)
#define HIFMC_DMA_MASK			(HIFMC_DMA_MAX_LEN - 1)
#define FMC_OP_DMA			0x68
#define OP_CTRL_RD_OPCODE(code)		(((code) & 0xff) << 16)
#define OP_CTRL_WR_OPCODE(code)		(((code) & 0xff) << 8)
#define OP_CTRL_RW_OP(op)		((op) << 1)
#define OP_CTRL_DMA_OP_READY		BIT(0)
#define FMC_OP_READ			0x0
#define FMC_OP_WRITE			0x1
#define FMC_WAIT_TIMEOUT		1000000

enum hifmc_iftype {
	IF_TYPE_STD,
	IF_TYPE_DUAL,
	IF_TYPE_DIO,
	IF_TYPE_QUAD,
	IF_TYPE_QIO,
};

struct hifmc_priv {
	u32 chipselect;
	u32 clkrate;
	struct hifmc_host *host;
};

#define HIFMC_MAX_CHIP_NUM		2
struct hifmc_host {
	struct device *dev;
	struct mutex lock;

	void __iomem *regbase;
	void __iomem *iobase;
	struct clk *clk;
	void *buffer;
	dma_addr_t dma_buffer;

	struct spi_nor	*nor[HIFMC_MAX_CHIP_NUM];
	u32 num_chip;
};

static inline int wait_op_finish(struct hifmc_host *host)
{
	u32 reg;

	return readl_poll_timeout(host->regbase + FMC_INT, reg,
		(reg & FMC_INT_OP_DONE), 0, FMC_WAIT_TIMEOUT);
}

static int get_if_type(enum spi_nor_protocol proto)
{
	enum hifmc_iftype if_type;

	switch (proto) {
	case SNOR_PROTO_1_1_2:
		if_type = IF_TYPE_DUAL;
		break;
	case SNOR_PROTO_1_2_2:
		if_type = IF_TYPE_DIO;
		break;
	case SNOR_PROTO_1_1_4:
		if_type = IF_TYPE_QUAD;
		break;
	case SNOR_PROTO_1_4_4:
		if_type = IF_TYPE_QIO;
		break;
	case SNOR_PROTO_1_1_1:
	default:
		if_type = IF_TYPE_STD;
		break;
	}

	return if_type;
}

static void hisi_spi_nor_init(struct hifmc_host *host)
{
	u32 reg;

	reg = TIMING_CFG_TCSH(CS_HOLD_TIME)
		| TIMING_CFG_TCSS(CS_SETUP_TIME)
		| TIMING_CFG_TSHSL(CS_DESELECT_TIME);
	writel(reg, host->regbase + FMC_SPI_TIMING_CFG);
}

static int hisi_spi_nor_prep(struct spi_nor *nor, enum spi_nor_ops ops)
{
	struct hifmc_priv *priv = nor->priv;
	struct hifmc_host *host = priv->host;
	int ret;

	mutex_lock(&host->lock);

	ret = clk_set_rate(host->clk, priv->clkrate);
	if (ret)
		goto out;

	ret = clk_prepare_enable(host->clk);
	if (ret)
		goto out;

	return 0;

out:
	mutex_unlock(&host->lock);
	return ret;
}

static void hisi_spi_nor_unprep(struct spi_nor *nor, enum spi_nor_ops ops)
{
	struct hifmc_priv *priv = nor->priv;
	struct hifmc_host *host = priv->host;

	clk_disable_unprepare(host->clk);
	mutex_unlock(&host->lock);
}

static int hisi_spi_nor_op_reg(struct spi_nor *nor,
				u8 opcode, int len, u8 optype)
{
	struct hifmc_priv *priv = nor->priv;
	struct hifmc_host *host = priv->host;
	u32 reg;

	reg = FMC_CMD_CMD1(opcode);
	writel(reg, host->regbase + FMC_CMD);

	reg = FMC_DATA_NUM_CNT(len);
	writel(reg, host->regbase + FMC_DATA_NUM);

	reg = OP_CFG_FM_CS(priv->chipselect);
	writel(reg, host->regbase + FMC_OP_CFG);

	writel(0xff, host->regbase + FMC_INT_CLR);
	reg = FMC_OP_CMD1_EN | FMC_OP_REG_OP_START | optype;
	writel(reg, host->regbase + FMC_OP);

	return wait_op_finish(host);
}

static int hisi_spi_nor_read_reg(struct spi_nor *nor, u8 opcode, u8 *buf,
		int len)
{
	struct hifmc_priv *priv = nor->priv;
	struct hifmc_host *host = priv->host;
	int ret;

	ret = hisi_spi_nor_op_reg(nor, opcode, len, FMC_OP_READ_DATA_EN);
	if (ret)
		return ret;

	memcpy_fromio(buf, host->iobase, len);
	return 0;
}

static int hisi_spi_nor_write_reg(struct spi_nor *nor, u8 opcode,
				u8 *buf, int len)
{
	struct hifmc_priv *priv = nor->priv;
	struct hifmc_host *host = priv->host;

	if (len)
		memcpy_toio(host->iobase, buf, len);

	return hisi_spi_nor_op_reg(nor, opcode, len, FMC_OP_WRITE_DATA_EN);
}

static int hisi_spi_nor_dma_transfer(struct spi_nor *nor, loff_t start_off,
		dma_addr_t dma_buf, size_t len, u8 op_type)
{
	struct hifmc_priv *priv = nor->priv;
	struct hifmc_host *host = priv->host;
	u8 if_type = 0;
	u32 reg;

	reg = readl(host->regbase + FMC_CFG);
	reg &= ~(FMC_CFG_OP_MODE_MASK | SPI_NOR_ADDR_MODE_MASK);
	reg |= FMC_CFG_OP_MODE_NORMAL;
	reg |= (nor->addr_width == 4) ? SPI_NOR_ADDR_MODE_4BYTES
		: SPI_NOR_ADDR_MODE_3BYTES;
	writel(reg, host->regbase + FMC_CFG);

	writel(start_off, host->regbase + FMC_ADDRL);
	writel(dma_buf, host->regbase + FMC_DMA_SADDR_D0);
	writel(FMC_DMA_LEN_SET(len), host->regbase + FMC_DMA_LEN);

	reg = OP_CFG_FM_CS(priv->chipselect);
	if (op_type == FMC_OP_READ)
		if_type = get_if_type(nor->read_proto);
	else
		if_type = get_if_type(nor->write_proto);
	reg |= OP_CFG_MEM_IF_TYPE(if_type);
	if (op_type == FMC_OP_READ)
		reg |= OP_CFG_DUMMY_NUM(nor->read_dummy >> 3);
	writel(reg, host->regbase + FMC_OP_CFG);

	writel(0xff, host->regbase + FMC_INT_CLR);
	reg = OP_CTRL_RW_OP(op_type) | OP_CTRL_DMA_OP_READY;
	reg |= (op_type == FMC_OP_READ)
		? OP_CTRL_RD_OPCODE(nor->read_opcode)
		: OP_CTRL_WR_OPCODE(nor->program_opcode);
	writel(reg, host->regbase + FMC_OP_DMA);

	return wait_op_finish(host);
}

static ssize_t hisi_spi_nor_read(struct spi_nor *nor, loff_t from, size_t len,
		u_char *read_buf)
{
	struct hifmc_priv *priv = nor->priv;
	struct hifmc_host *host = priv->host;
	size_t offset;
	int ret;

	for (offset = 0; offset < len; offset += HIFMC_DMA_MAX_LEN) {
		size_t trans = min_t(size_t, HIFMC_DMA_MAX_LEN, len - offset);

		ret = hisi_spi_nor_dma_transfer(nor,
			from + offset, host->dma_buffer, trans, FMC_OP_READ);
		if (ret) {
			dev_warn(nor->dev, "DMA read timeout\n");
			return ret;
		}
		memcpy(read_buf + offset, host->buffer, trans);
	}

	return len;
}

static ssize_t hisi_spi_nor_write(struct spi_nor *nor, loff_t to,
			size_t len, const u_char *write_buf)
{
	struct hifmc_priv *priv = nor->priv;
	struct hifmc_host *host = priv->host;
	size_t offset;
	int ret;

	for (offset = 0; offset < len; offset += HIFMC_DMA_MAX_LEN) {
		size_t trans = min_t(size_t, HIFMC_DMA_MAX_LEN, len - offset);

		memcpy(host->buffer, write_buf + offset, trans);
		ret = hisi_spi_nor_dma_transfer(nor,
			to + offset, host->dma_buffer, trans, FMC_OP_WRITE);
		if (ret) {
			dev_warn(nor->dev, "DMA write timeout\n");
			return ret;
		}
	}

	return len;
}

/**
 * Get spi flash device information and register it as a mtd device.
 */
static int hisi_spi_nor_register(struct device_node *np,
				struct hifmc_host *host)
{
	const struct spi_nor_hwcaps hwcaps = {
		.mask = SNOR_HWCAPS_READ |
			SNOR_HWCAPS_READ_FAST |
			SNOR_HWCAPS_READ_1_1_2 |
			SNOR_HWCAPS_READ_1_1_4 |
			SNOR_HWCAPS_PP,
	};
	struct device *dev = host->dev;
	struct spi_nor *nor;
	struct hifmc_priv *priv;
	struct mtd_info *mtd;
	int ret;

	nor = devm_kzalloc(dev, sizeof(*nor), GFP_KERNEL);
	if (!nor)
		return -ENOMEM;

	nor->dev = dev;
	spi_nor_set_flash_node(nor, np);

	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	ret = of_property_read_u32(np, "reg", &priv->chipselect);
	if (ret) {
		dev_err(dev, "There's no reg property for %pOF\n",
			np);
		return ret;
	}

	ret = of_property_read_u32(np, "spi-max-frequency",
			&priv->clkrate);
	if (ret) {
		dev_err(dev, "There's no spi-max-frequency property for %pOF\n",
			np);
		return ret;
	}
	priv->host = host;
	nor->priv = priv;

	nor->prepare = hisi_spi_nor_prep;
	nor->unprepare = hisi_spi_nor_unprep;
	nor->read_reg = hisi_spi_nor_read_reg;
	nor->write_reg = hisi_spi_nor_write_reg;
	nor->read = hisi_spi_nor_read;
	nor->write = hisi_spi_nor_write;
	nor->erase = NULL;
	ret = spi_nor_scan(nor, NULL, &hwcaps);
	if (ret)
		return ret;

	mtd = &nor->mtd;
	mtd->name = np->name;
	ret = mtd_device_register(mtd, NULL, 0);
	if (ret)
		return ret;

	host->nor[host->num_chip] = nor;
	host->num_chip++;
	return 0;
}

static void hisi_spi_nor_unregister_all(struct hifmc_host *host)
{
	int i;

	for (i = 0; i < host->num_chip; i++)
		mtd_device_unregister(&host->nor[i]->mtd);
}

static int hisi_spi_nor_register_all(struct hifmc_host *host)
{
	struct device *dev = host->dev;
	struct device_node *np;
	int ret;

	for_each_available_child_of_node(dev->of_node, np) {
		ret = hisi_spi_nor_register(np, host);
		if (ret)
			goto fail;

		if (host->num_chip == HIFMC_MAX_CHIP_NUM) {
			dev_warn(dev, "Flash device number exceeds the maximum chipselect number\n");
			break;
		}
	}

	return 0;

fail:
	hisi_spi_nor_unregister_all(host);
	return ret;
}

static int hisi_spi_nor_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct resource *res;
	struct hifmc_host *host;
	int ret;

	host = devm_kzalloc(dev, sizeof(*host), GFP_KERNEL);
	if (!host)
		return -ENOMEM;

	platform_set_drvdata(pdev, host);
	host->dev = dev;

	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "control");
	host->regbase = devm_ioremap_resource(dev, res);
	if (IS_ERR(host->regbase))
		return PTR_ERR(host->regbase);

	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "memory");
	host->iobase = devm_ioremap_resource(dev, res);
	if (IS_ERR(host->iobase))
		return PTR_ERR(host->iobase);

	host->clk = devm_clk_get(dev, NULL);
	if (IS_ERR(host->clk))
		return PTR_ERR(host->clk);

	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
	if (ret) {
		dev_warn(dev, "Unable to set dma mask\n");
		return ret;
	}

	host->buffer = dmam_alloc_coherent(dev, HIFMC_DMA_MAX_LEN,
			&host->dma_buffer, GFP_KERNEL);
	if (!host->buffer)
		return -ENOMEM;

	ret = clk_prepare_enable(host->clk);
	if (ret)
		return ret;

	mutex_init(&host->lock);
	hisi_spi_nor_init(host);
	ret = hisi_spi_nor_register_all(host);
	if (ret)
		mutex_destroy(&host->lock);

	clk_disable_unprepare(host->clk);
	return ret;
}

static int hisi_spi_nor_remove(struct platform_device *pdev)
{
	struct hifmc_host *host = platform_get_drvdata(pdev);

	hisi_spi_nor_unregister_all(host);
	mutex_destroy(&host->lock);
	clk_disable_unprepare(host->clk);
	return 0;
}

static const struct of_device_id hisi_spi_nor_dt_ids[] = {
	{ .compatible = "hisilicon,fmc-spi-nor"},
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, hisi_spi_nor_dt_ids);

static struct platform_driver hisi_spi_nor_driver = {
	.driver = {
		.name	= "hisi-sfc",
		.of_match_table = hisi_spi_nor_dt_ids,
	},
	.probe	= hisi_spi_nor_probe,
	.remove	= hisi_spi_nor_remove,
};
module_platform_driver(hisi_spi_nor_driver);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("HiSilicon SPI Nor Flash Controller Driver");