// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2020 Facebook */

#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/ptp_clock_kernel.h>

static const struct pci_device_id ptp_ocp_pcidev_id[] = {
	{ PCI_DEVICE(0x1d9b, 0x0400) },
	{ 0 }
};
MODULE_DEVICE_TABLE(pci, ptp_ocp_pcidev_id);

#define OCP_REGISTER_OFFSET	0x01000000

struct ocp_reg {
	u32	ctrl;
	u32	status;
	u32	select;
	u32	version;
	u32	time_ns;
	u32	time_sec;
	u32	__pad0[2];
	u32	adjust_ns;
	u32	adjust_sec;
	u32	__pad1[2];
	u32	offset_ns;
	u32	offset_window_ns;
};

#define OCP_CTRL_ENABLE		BIT(0)
#define OCP_CTRL_ADJUST_TIME	BIT(1)
#define OCP_CTRL_ADJUST_OFFSET	BIT(2)
#define OCP_CTRL_READ_TIME_REQ	BIT(30)
#define OCP_CTRL_READ_TIME_DONE	BIT(31)

#define OCP_STATUS_IN_SYNC	BIT(0)

#define OCP_SELECT_CLK_NONE	0
#define OCP_SELECT_CLK_REG	6

struct tod_reg {
	u32	ctrl;
	u32	status;
	u32	uart_polarity;
	u32	version;
	u32	correction_sec;
	u32	__pad0[3];
	u32	uart_baud;
	u32	__pad1[3];
	u32	utc_status;
	u32	leap;
};

#define TOD_REGISTER_OFFSET	0x01050000

#define TOD_CTRL_PROTOCOL	BIT(28)
#define TOD_CTRL_DISABLE_FMT_A	BIT(17)
#define TOD_CTRL_DISABLE_FMT_B	BIT(16)
#define TOD_CTRL_ENABLE		BIT(0)
#define TOD_CTRL_GNSS_MASK	((1U << 4) - 1)
#define TOD_CTRL_GNSS_SHIFT	24

#define TOD_STATUS_UTC_MASK	0xff
#define TOD_STATUS_UTC_VALID	BIT(8)
#define TOD_STATUS_LEAP_VALID	BIT(16)

struct ptp_ocp {
	struct pci_dev		*pdev;
	spinlock_t		lock;
	void __iomem		*base;
	struct ocp_reg __iomem	*reg;
	struct tod_reg __iomem	*tod;
	struct ptp_clock	*ptp;
	struct ptp_clock_info	ptp_info;
};

static int
__ptp_ocp_gettime_locked(struct ptp_ocp *bp, struct timespec64 *ts,
			 struct ptp_system_timestamp *sts)
{
	u32 ctrl, time_sec, time_ns;
	int i;

	ctrl = ioread32(&bp->reg->ctrl);
	ctrl |= OCP_CTRL_READ_TIME_REQ;

	ptp_read_system_prets(sts);
	iowrite32(ctrl, &bp->reg->ctrl);

	for (i = 0; i < 100; i++) {
		ctrl = ioread32(&bp->reg->ctrl);
		if (ctrl & OCP_CTRL_READ_TIME_DONE)
			break;
	}
	ptp_read_system_postts(sts);

	time_ns = ioread32(&bp->reg->time_ns);
	time_sec = ioread32(&bp->reg->time_sec);

	ts->tv_sec = time_sec;
	ts->tv_nsec = time_ns;

	return ctrl & OCP_CTRL_READ_TIME_DONE ? 0 : -ETIMEDOUT;
}

static int
ptp_ocp_gettimex(struct ptp_clock_info *ptp_info, struct timespec64 *ts,
		 struct ptp_system_timestamp *sts)
{
	struct ptp_ocp *bp = container_of(ptp_info, struct ptp_ocp, ptp_info);
	unsigned long flags;
	int err;

	spin_lock_irqsave(&bp->lock, flags);
	err = __ptp_ocp_gettime_locked(bp, ts, sts);
	spin_unlock_irqrestore(&bp->lock, flags);

	return err;
}

static void
__ptp_ocp_settime_locked(struct ptp_ocp *bp, const struct timespec64 *ts)
{
	u32 ctrl, time_sec, time_ns;
	u32 select;

	time_ns = ts->tv_nsec;
	time_sec = ts->tv_sec;

	select = ioread32(&bp->reg->select);
	iowrite32(OCP_SELECT_CLK_REG, &bp->reg->select);

	iowrite32(time_ns, &bp->reg->adjust_ns);
	iowrite32(time_sec, &bp->reg->adjust_sec);

	ctrl = ioread32(&bp->reg->ctrl);
	ctrl |= OCP_CTRL_ADJUST_TIME;
	iowrite32(ctrl, &bp->reg->ctrl);

	/* restore clock selection */
	iowrite32(select >> 16, &bp->reg->select);
}

static int
ptp_ocp_settime(struct ptp_clock_info *ptp_info, const struct timespec64 *ts)
{
	struct ptp_ocp *bp = container_of(ptp_info, struct ptp_ocp, ptp_info);
	unsigned long flags;

	if (ioread32(&bp->reg->status) & OCP_STATUS_IN_SYNC)
		return 0;

	spin_lock_irqsave(&bp->lock, flags);
	__ptp_ocp_settime_locked(bp, ts);
	spin_unlock_irqrestore(&bp->lock, flags);

	return 0;
}

static int
ptp_ocp_adjtime(struct ptp_clock_info *ptp_info, s64 delta_ns)
{
	struct ptp_ocp *bp = container_of(ptp_info, struct ptp_ocp, ptp_info);
	struct timespec64 ts;
	unsigned long flags;
	int err;

	if (ioread32(&bp->reg->status) & OCP_STATUS_IN_SYNC)
		return 0;

	spin_lock_irqsave(&bp->lock, flags);
	err = __ptp_ocp_gettime_locked(bp, &ts, NULL);
	if (likely(!err)) {
		timespec64_add_ns(&ts, delta_ns);
		__ptp_ocp_settime_locked(bp, &ts);
	}
	spin_unlock_irqrestore(&bp->lock, flags);

	return err;
}

static int
ptp_ocp_null_adjfine(struct ptp_clock_info *ptp_info, long scaled_ppm)
{
	if (scaled_ppm == 0)
		return 0;

	return -EOPNOTSUPP;
}

static const struct ptp_clock_info ptp_ocp_clock_info = {
	.owner		= THIS_MODULE,
	.name		= KBUILD_MODNAME,
	.max_adj	= 100000000,
	.gettimex64	= ptp_ocp_gettimex,
	.settime64	= ptp_ocp_settime,
	.adjtime	= ptp_ocp_adjtime,
	.adjfine	= ptp_ocp_null_adjfine,
};

static int
ptp_ocp_check_clock(struct ptp_ocp *bp)
{
	struct timespec64 ts;
	bool sync;
	u32 ctrl;

	/* make sure clock is enabled */
	ctrl = ioread32(&bp->reg->ctrl);
	ctrl |= OCP_CTRL_ENABLE;
	iowrite32(ctrl, &bp->reg->ctrl);

	if ((ioread32(&bp->reg->ctrl) & OCP_CTRL_ENABLE) == 0) {
		dev_err(&bp->pdev->dev, "clock not enabled\n");
		return -ENODEV;
	}

	sync = ioread32(&bp->reg->status) & OCP_STATUS_IN_SYNC;
	if (!sync) {
		ktime_get_real_ts64(&ts);
		ptp_ocp_settime(&bp->ptp_info, &ts);
	}
	if (!ptp_ocp_gettimex(&bp->ptp_info, &ts, NULL))
		dev_info(&bp->pdev->dev, "Time: %lld.%ld, %s\n",
			 ts.tv_sec, ts.tv_nsec,
			 sync ? "in-sync" : "UNSYNCED");

	return 0;
}

static void
ptp_ocp_tod_info(struct ptp_ocp *bp)
{
	static const char * const proto_name[] = {
		"NMEA", "NMEA_ZDA", "NMEA_RMC", "NMEA_none",
		"UBX", "UBX_UTC", "UBX_LS", "UBX_none"
	};
	static const char * const gnss_name[] = {
		"ALL", "COMBINED", "GPS", "GLONASS", "GALILEO", "BEIDOU",
	};
	u32 version, ctrl, reg;
	int idx;

	version = ioread32(&bp->tod->version);
	dev_info(&bp->pdev->dev, "TOD Version %d.%d.%d\n",
		 version >> 24, (version >> 16) & 0xff, version & 0xffff);

	ctrl = ioread32(&bp->tod->ctrl);
	ctrl |= TOD_CTRL_PROTOCOL | TOD_CTRL_ENABLE;
	ctrl &= ~(TOD_CTRL_DISABLE_FMT_A | TOD_CTRL_DISABLE_FMT_B);
	iowrite32(ctrl, &bp->tod->ctrl);

	ctrl = ioread32(&bp->tod->ctrl);
	idx = ctrl & TOD_CTRL_PROTOCOL ? 4 : 0;
	idx += (ctrl >> 16) & 3;
	dev_info(&bp->pdev->dev, "control: %x\n", ctrl);
	dev_info(&bp->pdev->dev, "TOD Protocol %s %s\n", proto_name[idx],
		 ctrl & TOD_CTRL_ENABLE ? "enabled" : "");

	idx = (ctrl >> TOD_CTRL_GNSS_SHIFT) & TOD_CTRL_GNSS_MASK;
	if (idx < ARRAY_SIZE(gnss_name))
		dev_info(&bp->pdev->dev, "GNSS %s\n", gnss_name[idx]);

	reg = ioread32(&bp->tod->status);
	dev_info(&bp->pdev->dev, "status: %x\n", reg);

	reg = ioread32(&bp->tod->correction_sec);
	dev_info(&bp->pdev->dev, "correction: %d\n", reg);

	reg = ioread32(&bp->tod->utc_status);
	dev_info(&bp->pdev->dev, "utc_status: %x\n", reg);
	dev_info(&bp->pdev->dev, "utc_offset: %d  valid:%d  leap_valid:%d\n",
		 reg & TOD_STATUS_UTC_MASK, reg & TOD_STATUS_UTC_VALID ? 1 : 0,
		 reg & TOD_STATUS_LEAP_VALID ? 1 : 0);
}

static void
ptp_ocp_info(struct ptp_ocp *bp)
{
	static const char * const clock_name[] = {
		"NO", "TOD", "IRIG", "PPS", "PTP", "RTC", "REGS", "EXT"
	};
	u32 version, select;

	version = ioread32(&bp->reg->version);
	select = ioread32(&bp->reg->select);
	dev_info(&bp->pdev->dev, "Version %d.%d.%d, clock %s, device ptp%d\n",
		 version >> 24, (version >> 16) & 0xff, version & 0xffff,
		 clock_name[select & 7],
		 ptp_clock_index(bp->ptp));

	ptp_ocp_tod_info(bp);
}

static int
ptp_ocp_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
	struct ptp_ocp *bp;
	int err;

	bp = kzalloc(sizeof(*bp), GFP_KERNEL);
	if (!bp)
		return -ENOMEM;
	bp->pdev = pdev;
	pci_set_drvdata(pdev, bp);

	err = pci_enable_device(pdev);
	if (err) {
		dev_err(&pdev->dev, "pci_enable_device\n");
		goto out_free;
	}

	err = pci_request_regions(pdev, KBUILD_MODNAME);
	if (err) {
		dev_err(&pdev->dev, "pci_request_region\n");
		goto out_disable;
	}

	bp->base = pci_ioremap_bar(pdev, 0);
	if (!bp->base) {
		dev_err(&pdev->dev, "io_remap bar0\n");
		err = -ENOMEM;
		goto out;
	}
	bp->reg = bp->base + OCP_REGISTER_OFFSET;
	bp->tod = bp->base + TOD_REGISTER_OFFSET;
	bp->ptp_info = ptp_ocp_clock_info;
	spin_lock_init(&bp->lock);

	err = ptp_ocp_check_clock(bp);
	if (err)
		goto out;

	bp->ptp = ptp_clock_register(&bp->ptp_info, &pdev->dev);
	if (IS_ERR(bp->ptp)) {
		dev_err(&pdev->dev, "ptp_clock_register\n");
		err = PTR_ERR(bp->ptp);
		goto out;
	}

	ptp_ocp_info(bp);

	return 0;

out:
	pci_release_regions(pdev);
out_disable:
	pci_disable_device(pdev);
out_free:
	kfree(bp);

	return err;
}

static void
ptp_ocp_remove(struct pci_dev *pdev)
{
	struct ptp_ocp *bp = pci_get_drvdata(pdev);

	ptp_clock_unregister(bp->ptp);
	pci_iounmap(pdev, bp->base);
	pci_release_regions(pdev);
	pci_disable_device(pdev);
	pci_set_drvdata(pdev, NULL);
	kfree(bp);
}

static struct pci_driver ptp_ocp_driver = {
	.name		= KBUILD_MODNAME,
	.id_table	= ptp_ocp_pcidev_id,
	.probe		= ptp_ocp_probe,
	.remove		= ptp_ocp_remove,
};

static int __init
ptp_ocp_init(void)
{
	int err;

	err = pci_register_driver(&ptp_ocp_driver);
	return err;
}

static void __exit
ptp_ocp_fini(void)
{
	pci_unregister_driver(&ptp_ocp_driver);
}

module_init(ptp_ocp_init);
module_exit(ptp_ocp_fini);

MODULE_DESCRIPTION("OpenCompute TimeCard driver");
MODULE_LICENSE("GPL v2");