// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2019 Nuvoton Technology corporation

#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/interrupt.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/peci.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/reset.h>

/* NPCM GCR module */
#define NPCM_INTCR3_OFFSET	0x9C
#define NPCM_INTCR3_PECIVSEL	BIT(19)

/* NPCM PECI Registers */
#define NPCM_PECI_CTL_STS	0x00
#define NPCM_PECI_RD_LENGTH	0x04
#define NPCM_PECI_ADDR		0x08
#define NPCM_PECI_CMD		0x0C
#define NPCM_PECI_CTL2		0x10
#define NPCM_PECI_WR_LENGTH	0x1C
#define NPCM_PECI_PDDR		0x2C
#define NPCM_PECI_DAT_INOUT(n)	(0x100 + ((n) * 4))

#define NPCM_PECI_MAX_REG	0x200

/* NPCM_PECI_CTL_STS - 0x00 : Control Register */
#define NPCM_PECI_CTRL_DONE_INT_EN	BIT(6)
#define NPCM_PECI_CTRL_ABRT_ERR		BIT(4)
#define NPCM_PECI_CTRL_CRC_ERR		BIT(3)
#define NPCM_PECI_CTRL_DONE		BIT(1)
#define NPCM_PECI_CTRL_START_BUSY	BIT(0)

/* NPCM_PECI_RD_LENGTH - 0x04 : Command Register */
#define NPCM_PECI_RD_LEN_MASK		GENMASK(6, 0)

/* NPCM_PECI_CMD - 0x10 : Command Register */
#define NPCM_PECI_CTL2_MASK		GENMASK(7, 6)

/* NPCM_PECI_WR_LENGTH - 0x1C : Command Register */
#define NPCM_PECI_WR_LEN_MASK		GENMASK(6, 0)

/* NPCM_PECI_PDDR - 0x2C : Command Register */
#define NPCM_PECI_PDDR_MASK		GENMASK(4, 0)

#define NPCM_PECI_INT_MASK		(NPCM_PECI_CTRL_ABRT_ERR | \
					 NPCM_PECI_CTRL_CRC_ERR  | \
					 NPCM_PECI_CTRL_DONE)

#define NPCM_PECI_IDLE_CHECK_TIMEOUT_USEC	(50 * USEC_PER_MSEC)
#define NPCM_PECI_IDLE_CHECK_INTERVAL_USEC	(10 * USEC_PER_MSEC)
#define NPCM_PECI_CMD_TIMEOUT_MS_DEFAULT	1000
#define NPCM_PECI_CMD_TIMEOUT_MS_MAX		60000
#define NPCM_PECI_HOST_NEG_BIT_RATE_DEFAULT	15
#define NPCM_PECI_PULL_DOWN_DEFAULT		0

struct npcm_peci {
	u32			cmd_timeout_ms;
	struct completion	xfer_complete;
	struct regmap		*regmap;
	u32			status;
	spinlock_t		lock; /* to sync completion status handling */
	struct peci_controller *controller;
	struct device		*dev;
	struct clk		*clk;
	int			irq;
};

static int npcm_peci_xfer(struct peci_controller *controller, u8 addr, struct peci_request *req)
{
	struct npcm_peci *priv = dev_get_drvdata(controller->dev.parent);
	unsigned long timeout = msecs_to_jiffies(priv->cmd_timeout_ms);
	unsigned int msg_rd;
	u32 cmd_sts;
	int i, ret;

	/* Check command sts and bus idle state */
	ret = regmap_read_poll_timeout(priv->regmap, NPCM_PECI_CTL_STS, cmd_sts,
				       !(cmd_sts & NPCM_PECI_CTRL_START_BUSY),
				       NPCM_PECI_IDLE_CHECK_INTERVAL_USEC,
				       NPCM_PECI_IDLE_CHECK_TIMEOUT_USEC);
	if (ret)
		return ret; /* -ETIMEDOUT */

	spin_lock_irq(&priv->lock);
	reinit_completion(&priv->xfer_complete);

	regmap_write(priv->regmap, NPCM_PECI_ADDR, addr);
	regmap_write(priv->regmap, NPCM_PECI_RD_LENGTH, NPCM_PECI_WR_LEN_MASK & req->rx.len);
	regmap_write(priv->regmap, NPCM_PECI_WR_LENGTH, NPCM_PECI_WR_LEN_MASK & req->tx.len);

	if (req->tx.len) {
		regmap_write(priv->regmap, NPCM_PECI_CMD, req->tx.buf[0]);

		for (i = 0; i < (req->tx.len - 1); i++)
			regmap_write(priv->regmap, NPCM_PECI_DAT_INOUT(i), req->tx.buf[i + 1]);
	}

#if IS_ENABLED(CONFIG_DYNAMIC_DEBUG)
	dev_dbg(priv->dev, "addr : %#02x, tx.len : %#02x, rx.len : %#02x\n",
		addr, req->tx.len, req->rx.len);
	print_hex_dump_bytes("TX : ", DUMP_PREFIX_NONE, req->tx.buf, req->tx.len);
#endif

	priv->status = 0;
	regmap_update_bits(priv->regmap, NPCM_PECI_CTL_STS, NPCM_PECI_CTRL_START_BUSY,
			   NPCM_PECI_CTRL_START_BUSY);

	spin_unlock_irq(&priv->lock);

	ret = wait_for_completion_interruptible_timeout(&priv->xfer_complete, timeout);
	if (ret < 0)
		return ret;

	if (ret == 0) {
		dev_dbg(priv->dev, "timeout waiting for a response\n");
		return -ETIMEDOUT;
	}

	spin_lock_irq(&priv->lock);

	if (priv->status != NPCM_PECI_CTRL_DONE) {
		spin_unlock_irq(&priv->lock);
		dev_dbg(priv->dev, "no valid response, status: %#02x\n", priv->status);
		return -EIO;
	}

	regmap_write(priv->regmap, NPCM_PECI_CMD, 0);

	for (i = 0; i < req->rx.len; i++) {
		regmap_read(priv->regmap, NPCM_PECI_DAT_INOUT(i), &msg_rd);
		req->rx.buf[i] = (u8)msg_rd;
	}

	spin_unlock_irq(&priv->lock);

#if IS_ENABLED(CONFIG_DYNAMIC_DEBUG)
	print_hex_dump_bytes("RX : ", DUMP_PREFIX_NONE, req->rx.buf, req->rx.len);
#endif
	return 0;
}

static irqreturn_t npcm_peci_irq_handler(int irq, void *arg)
{
	struct npcm_peci *priv = arg;
	u32 status_ack = 0;
	u32 status;

	spin_lock(&priv->lock);
	regmap_read(priv->regmap, NPCM_PECI_CTL_STS, &status);
	priv->status |= (status & NPCM_PECI_INT_MASK);

	if (status & NPCM_PECI_CTRL_CRC_ERR)
		status_ack |= NPCM_PECI_CTRL_CRC_ERR;

	if (status & NPCM_PECI_CTRL_ABRT_ERR)
		status_ack |= NPCM_PECI_CTRL_ABRT_ERR;

	/*
	 * All commands should be ended up with a NPCM_PECI_CTRL_DONE
	 * bit set even in an error case.
	 */
	if (status & NPCM_PECI_CTRL_DONE) {
		status_ack |= NPCM_PECI_CTRL_DONE;
		complete(&priv->xfer_complete);
	}

	regmap_write_bits(priv->regmap, NPCM_PECI_CTL_STS, NPCM_PECI_INT_MASK, status_ack);

	spin_unlock(&priv->lock);
	return IRQ_HANDLED;
}

static int npcm_peci_init_ctrl(struct npcm_peci *priv)
{
	u32 cmd_sts;
	int ret;

	priv->clk = devm_clk_get_enabled(priv->dev, NULL);
	if (IS_ERR(priv->clk)) {
		dev_err(priv->dev, "failed to get ref clock\n");
		return PTR_ERR(priv->clk);
	}

	ret = device_property_read_u32(priv->dev, "cmd-timeout-ms", &priv->cmd_timeout_ms);
	if (ret) {
		priv->cmd_timeout_ms = NPCM_PECI_CMD_TIMEOUT_MS_DEFAULT;
	} else if (priv->cmd_timeout_ms > NPCM_PECI_CMD_TIMEOUT_MS_MAX ||
		   priv->cmd_timeout_ms == 0) {
		dev_warn(priv->dev, "invalid cmd-timeout-ms: %u, falling back to: %u\n",
			 priv->cmd_timeout_ms, NPCM_PECI_CMD_TIMEOUT_MS_DEFAULT);

		priv->cmd_timeout_ms = NPCM_PECI_CMD_TIMEOUT_MS_DEFAULT;
	}

	regmap_update_bits(priv->regmap, NPCM_PECI_CTL2, NPCM_PECI_CTL2_MASK,
			   NPCM_PECI_PULL_DOWN_DEFAULT << 6);

	regmap_update_bits(priv->regmap, NPCM_PECI_PDDR, NPCM_PECI_PDDR_MASK,
			   NPCM_PECI_HOST_NEG_BIT_RATE_DEFAULT);

	ret = regmap_read_poll_timeout(priv->regmap, NPCM_PECI_CTL_STS, cmd_sts,
				       !(cmd_sts & NPCM_PECI_CTRL_START_BUSY),
				       NPCM_PECI_IDLE_CHECK_INTERVAL_USEC,
				       NPCM_PECI_IDLE_CHECK_TIMEOUT_USEC);
	if (ret)
		return ret; /* -ETIMEDOUT */

	/* PECI interrupt enable */
	regmap_update_bits(priv->regmap, NPCM_PECI_CTL_STS, NPCM_PECI_CTRL_DONE_INT_EN,
			   NPCM_PECI_CTRL_DONE_INT_EN);

	return 0;
}

static const struct regmap_config npcm_peci_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.max_register = NPCM_PECI_MAX_REG,
	.fast_io = true,
};

static const struct peci_controller_ops npcm_ops = {
	.xfer = npcm_peci_xfer,
};

static int npcm_peci_probe(struct platform_device *pdev)
{
	struct peci_controller *controller;
	struct npcm_peci *priv;
	void __iomem *base;
	int ret;

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

	priv->dev = &pdev->dev;
	dev_set_drvdata(&pdev->dev, priv);

	base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(base))
		return PTR_ERR(base);

	priv->regmap = devm_regmap_init_mmio(&pdev->dev, base, &npcm_peci_regmap_config);
	if (IS_ERR(priv->regmap))
		return PTR_ERR(priv->regmap);

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

	ret = devm_request_irq(&pdev->dev, priv->irq, npcm_peci_irq_handler,
			       0, "peci-npcm-irq", priv);
	if (ret)
		return ret;

	init_completion(&priv->xfer_complete);
	spin_lock_init(&priv->lock);

	ret = npcm_peci_init_ctrl(priv);
	if (ret)
		return ret;

	controller = devm_peci_controller_add(priv->dev, &npcm_ops);
	if (IS_ERR(controller))
		return dev_err_probe(priv->dev, PTR_ERR(controller),
				     "failed to add npcm peci controller\n");

	priv->controller = controller;

	return 0;
}

static const struct of_device_id npcm_peci_of_table[] = {
	{ .compatible = "nuvoton,npcm750-peci", },
	{ .compatible = "nuvoton,npcm845-peci", },
	{ }
};
MODULE_DEVICE_TABLE(of, npcm_peci_of_table);

static struct platform_driver npcm_peci_driver = {
	.probe  = npcm_peci_probe,
	.driver = {
		.name           = KBUILD_MODNAME,
		.of_match_table = npcm_peci_of_table,
	},
};
module_platform_driver(npcm_peci_driver);

MODULE_AUTHOR("Tomer Maimon <tomer.maimon@nuvoton.com>");
MODULE_DESCRIPTION("NPCM PECI driver");
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS("PECI");