// 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/mfd/syscon.h>
#include <linux/reset.h>

/* NPCM7xx GCR module */
#define NPCM7XX_INTCR3_OFFSET		0x9C
#define NPCM7XX_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	50000
#define NPCM_PECI_IDLE_CHECK_INTERVAL_USEC	10000
#define NPCM_PECI_CMD_TIMEOUT_MS_DEFAULT	1000
#define NPCM_PECI_CMD_TIMEOUT_MS_MAX		60000
#define NPCM_PECI_HOST_NEG_BIT_RATE_MAX		31
#define NPCM_PECI_HOST_NEG_BIT_RATE_MIN		7
#define NPCM_PECI_HOST_NEG_BIT_RATE_DEFAULT	15
#define NPCM_PECI_PULL_DOWN_DEFAULT		0
#define NPCM_PECI_PULL_DOWN_MAX			2

struct npcm_peci {
	u32			cmd_timeout_ms;
	u32			host_bit_rate;
	struct completion	xfer_complete;
	struct regmap		*gcr_regmap;
	struct peci_adapter	*adapter;
	struct regmap		*regmap;
	u32			status;
	spinlock_t		lock; /* to sync completion status handling */
	struct device		*dev;
	struct clk		*clk;
	int			irq;
};

static int npcm_peci_xfer_native(struct npcm_peci *priv,
				 struct peci_xfer_msg *msg)
{
	long err, timeout = msecs_to_jiffies(priv->cmd_timeout_ms);
	unsigned long flags;
	unsigned int msg_rd;
	u32 cmd_sts;
	int i, rc;

	/* Check command sts and bus idle state */
	rc = 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 (rc)
		return rc; /* -ETIMEDOUT */

	spin_lock_irqsave(&priv->lock, flags);
	reinit_completion(&priv->xfer_complete);

	regmap_write(priv->regmap, NPCM_PECI_ADDR, msg->addr);
	regmap_write(priv->regmap, NPCM_PECI_RD_LENGTH,
		     NPCM_PECI_WR_LEN_MASK & msg->rx_len);
	regmap_write(priv->regmap, NPCM_PECI_WR_LENGTH,
		     NPCM_PECI_WR_LEN_MASK & msg->tx_len);

	if (msg->tx_len) {
		regmap_write(priv->regmap, NPCM_PECI_CMD, msg->tx_buf[0]);

		for (i = 0; i < (msg->tx_len - 1); i++)
			regmap_write(priv->regmap, NPCM_PECI_DAT_INOUT(i),
				     msg->tx_buf[i + 1]);
	}

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

	spin_unlock_irqrestore(&priv->lock, flags);

	err = wait_for_completion_interruptible_timeout(&priv->xfer_complete,
							timeout);

	spin_lock_irqsave(&priv->lock, flags);

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

	if (err <= 0 || priv->status  != NPCM_PECI_CTRL_DONE) {
		if (err < 0) { /* -ERESTARTSYS */
			rc = (int)err;
			goto err_irqrestore;
		} else if (err == 0) {
			dev_dbg(priv->dev, "Timeout waiting for a response!\n");
			rc = -ETIMEDOUT;
			goto err_irqrestore;
		}

		dev_dbg(priv->dev, "No valid response!\n");
		rc = -EIO;
		goto err_irqrestore;
	}

	for (i = 0; i < msg->rx_len; i++) {
		regmap_read(priv->regmap, NPCM_PECI_DAT_INOUT(i), &msg_rd);
		msg->rx_buf[i] = (u8)msg_rd;
	}

err_irqrestore:
	spin_unlock_irqrestore(&priv->lock, flags);
	return rc;
}

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) {
		dev_dbg(priv->dev, "PECI_INT_W_FCS_BAD\n");
		status_ack |= NPCM_PECI_CTRL_CRC_ERR;
	}

	if (status & NPCM_PECI_CTRL_ABRT_ERR) {
		dev_dbg(priv->dev, "NPCM_PECI_CTRL_ABRT_ERR\n");
		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) {
		dev_dbg(priv->dev, "NPCM_PECI_CTRL_DONE\n");
		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, host_neg_bit_rate = 0, pull_down = 0;
	int ret;
	bool volt;

	priv->clk = devm_clk_get(priv->dev, NULL);
	if (IS_ERR(priv->clk)) {
		dev_err(priv->dev, "Failed to get clk source.\n");
		return PTR_ERR(priv->clk);
	}

	ret = clk_prepare_enable(priv->clk);
	if (ret) {
		dev_err(priv->dev, "Failed to enable clock.\n");
		return ret;
	}

	ret = of_property_read_u32(priv->dev->of_node, "cmd-timeout-ms",
				   &priv->cmd_timeout_ms);
	if (ret || priv->cmd_timeout_ms > NPCM_PECI_CMD_TIMEOUT_MS_MAX ||
	    priv->cmd_timeout_ms == 0) {
		if (ret)
			dev_warn(priv->dev,
				 "cmd-timeout-ms not found, use default : %u\n",
				 NPCM_PECI_CMD_TIMEOUT_MS_DEFAULT);
		else
			dev_warn(priv->dev,
				 "Invalid cmd-timeout-ms : %u. Use default : %u\n",
				 priv->cmd_timeout_ms,
				 NPCM_PECI_CMD_TIMEOUT_MS_DEFAULT);

		priv->cmd_timeout_ms = NPCM_PECI_CMD_TIMEOUT_MS_DEFAULT;
	}

	if (of_device_is_compatible(priv->dev->of_node,
				    "nuvoton,npcm750-peci")) {
		priv->gcr_regmap = syscon_regmap_lookup_by_compatible
			("nuvoton,npcm750-gcr");
		if (!IS_ERR(priv->gcr_regmap)) {
			volt = of_property_read_bool(priv->dev->of_node,
						     "high-volt-range");
			if (volt)
				regmap_update_bits(priv->gcr_regmap,
						   NPCM7XX_INTCR3_OFFSET,
						   NPCM7XX_INTCR3_PECIVSEL,
						   NPCM7XX_INTCR3_PECIVSEL);
			else
				regmap_update_bits(priv->gcr_regmap,
						   NPCM7XX_INTCR3_OFFSET,
						   NPCM7XX_INTCR3_PECIVSEL, 0);
		}
	}

	ret = of_property_read_u32(priv->dev->of_node, "pull-down",
				   &pull_down);
	if (ret || pull_down > NPCM_PECI_PULL_DOWN_MAX) {
		if (ret)
			dev_warn(priv->dev,
				 "pull-down not found, use default : %u\n",
				 NPCM_PECI_PULL_DOWN_DEFAULT);
		else
			dev_warn(priv->dev,
				 "Invalid pull-down : %u. Use default : %u\n",
				 pull_down,
				 NPCM_PECI_PULL_DOWN_DEFAULT);
		pull_down = NPCM_PECI_PULL_DOWN_DEFAULT;
	}

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

	ret = of_property_read_u32(priv->dev->of_node, "host-neg-bit-rate",
				   &host_neg_bit_rate);
	if (ret || host_neg_bit_rate > NPCM_PECI_HOST_NEG_BIT_RATE_MAX ||
	    host_neg_bit_rate < NPCM_PECI_HOST_NEG_BIT_RATE_MIN) {
		if (ret)
			dev_warn(priv->dev,
				 "host-neg-bit-rate not found, use default : %u\n",
				 NPCM_PECI_HOST_NEG_BIT_RATE_DEFAULT);
		else
			dev_warn(priv->dev,
				 "Invalid host-neg-bit-rate : %u. Use default : %u\n",
				 host_neg_bit_rate,
				 NPCM_PECI_HOST_NEG_BIT_RATE_DEFAULT);
		host_neg_bit_rate = NPCM_PECI_HOST_NEG_BIT_RATE_DEFAULT;
	}

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

	priv->host_bit_rate = clk_get_rate(priv->clk) /
		(4 * (host_neg_bit_rate + 1));

	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 int npcm_peci_xfer(struct peci_adapter *adapter,
			  struct peci_xfer_msg *msg)
{
	struct npcm_peci *priv = peci_get_adapdata(adapter);

	return npcm_peci_xfer_native(priv, msg);
}

static int npcm_peci_probe(struct platform_device *pdev)
{
	struct peci_adapter *adapter;
	struct npcm_peci *priv;
	struct resource *res;
	void __iomem *base;
	int ret;

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

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

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(base)) {
		ret = PTR_ERR(base);
		goto err_put_adapter_dev;
	}

	priv->regmap = devm_regmap_init_mmio(&pdev->dev, base,
					     &npcm_peci_regmap_config);
	if (IS_ERR(priv->regmap)) {
		ret = PTR_ERR(priv->regmap);
		goto err_put_adapter_dev;
	}

	priv->irq = platform_get_irq(pdev, 0);
	if (!priv->irq) {
		ret = -ENODEV;
		goto err_put_adapter_dev;
	}

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

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

	priv->adapter->owner = THIS_MODULE;
	priv->adapter->dev.of_node = of_node_get(dev_of_node(priv->dev));
	strlcpy(priv->adapter->name, pdev->name, sizeof(priv->adapter->name));
	priv->adapter->xfer = npcm_peci_xfer;

	ret = npcm_peci_init_ctrl(priv);
	if (ret)
		goto err_put_adapter_dev;

	ret = peci_add_adapter(priv->adapter);
	if (ret)
		goto err_put_adapter_dev;

	dev_info(&pdev->dev, "peci bus %d registered, host negotiation bit rate %dHz",
		 priv->adapter->nr, priv->host_bit_rate);

	return 0;

err_put_adapter_dev:
	put_device(&adapter->dev);
	return ret;
}

static int npcm_peci_remove(struct platform_device *pdev)
{
	struct npcm_peci *priv = dev_get_drvdata(&pdev->dev);

	clk_disable_unprepare(priv->clk);
	peci_del_adapter(priv->adapter);
	of_node_put(priv->adapter->dev.of_node);

	return 0;
}

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

static struct platform_driver npcm_peci_driver = {
	.probe  = npcm_peci_probe,
	.remove = npcm_peci_remove,
	.driver = {
		.name           = "peci-npcm",
		.of_match_table = of_match_ptr(npcm_peci_of_table),
	},
};
module_platform_driver(npcm_peci_driver);

MODULE_AUTHOR("Tomer Maimon <tomer.maimon@nuvoton.com>");
MODULE_DESCRIPTION("NPCM Platform Environment Control Interface (PECI) driver");
MODULE_LICENSE("GPL v2");