// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2020 Synopsys, Inc. and/or its affiliates.
 * Synopsys DesignWare xData driver
 *
 * Author: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
 */

#include <linux/miscdevice.h>
#include <linux/bitfield.h>
#include <linux/pci-epf.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/bitops.h>
#include <linux/mutex.h>
#include <linux/delay.h>
#include <linux/pci.h>

#define DW_XDATA_DRIVER_NAME		"dw-xdata-pcie"

#define DW_XDATA_EP_MEM_OFFSET		0x8000000

static DEFINE_IDA(xdata_ida);

#define STATUS_DONE			BIT(0)

#define CONTROL_DOORBELL		BIT(0)
#define CONTROL_IS_WRITE		BIT(1)
#define CONTROL_LENGTH(a)		FIELD_PREP(GENMASK(13, 2), a)
#define CONTROL_PATTERN_INC		BIT(16)
#define CONTROL_NO_ADDR_INC		BIT(18)

#define XPERF_CONTROL_ENABLE		BIT(5)

#define BURST_REPEAT			BIT(31)
#define BURST_VALUE			0x1001

#define PATTERN_VALUE			0x0

struct dw_xdata_regs {
	u32 addr_lsb;					/* 0x000 */
	u32 addr_msb;					/* 0x004 */
	u32 burst_cnt;					/* 0x008 */
	u32 control;					/* 0x00c */
	u32 pattern;					/* 0x010 */
	u32 status;					/* 0x014 */
	u32 RAM_addr;					/* 0x018 */
	u32 RAM_port;					/* 0x01c */
	u32 _reserved0[14];				/* 0x020..0x054 */
	u32 perf_control;				/* 0x058 */
	u32 _reserved1[41];				/* 0x05c..0x0fc */
	u32 wr_cnt_lsb;					/* 0x100 */
	u32 wr_cnt_msb;					/* 0x104 */
	u32 rd_cnt_lsb;					/* 0x108 */
	u32 rd_cnt_msb;					/* 0x10c */
} __packed;

struct dw_xdata_region {
	phys_addr_t paddr;				/* physical address */
	void __iomem *vaddr;				/* virtual address */
};

struct dw_xdata {
	struct dw_xdata_region rg_region;		/* registers */
	size_t max_wr_len;				/* max wr xfer len */
	size_t max_rd_len;				/* max rd xfer len */
	struct mutex mutex;
	struct pci_dev *pdev;
	struct miscdevice misc_dev;
};

static inline struct dw_xdata_regs __iomem *__dw_regs(struct dw_xdata *dw)
{
	return dw->rg_region.vaddr;
}

static void dw_xdata_stop(struct dw_xdata *dw)
{
	u32 burst;

	mutex_lock(&dw->mutex);

	burst = readl(&(__dw_regs(dw)->burst_cnt));

	if (burst & BURST_REPEAT) {
		burst &= ~(u32)BURST_REPEAT;
		writel(burst, &(__dw_regs(dw)->burst_cnt));
	}

	mutex_unlock(&dw->mutex);
}

static void dw_xdata_start(struct dw_xdata *dw, bool write)
{
	struct device *dev = &dw->pdev->dev;
	u32 control, status;

	/* Stop first if xfer in progress */
	dw_xdata_stop(dw);

	mutex_lock(&dw->mutex);

	/* Clear status register */
	writel(0x0, &(__dw_regs(dw)->status));

	/* Burst count register set for continuous until stopped */
	writel(BURST_REPEAT | BURST_VALUE, &(__dw_regs(dw)->burst_cnt));

	/* Pattern register */
	writel(PATTERN_VALUE, &(__dw_regs(dw)->pattern));

	/* Control register */
	control = CONTROL_DOORBELL | CONTROL_PATTERN_INC | CONTROL_NO_ADDR_INC;
	if (write) {
		control |= CONTROL_IS_WRITE;
		control |= CONTROL_LENGTH(dw->max_wr_len);
	} else {
		control |= CONTROL_LENGTH(dw->max_rd_len);
	}
	writel(control, &(__dw_regs(dw)->control));

	/*
	 * The xData HW block needs about 100 ms to initiate the traffic
	 * generation according this HW block datasheet.
	 */
	usleep_range(100, 150);

	status = readl(&(__dw_regs(dw)->status));

	mutex_unlock(&dw->mutex);

	if (!(status & STATUS_DONE))
		dev_dbg(dev, "xData: started %s direction\n",
			write ? "write" : "read");
}

static void dw_xdata_perf_meas(struct dw_xdata *dw, u64 *data, bool write)
{
	if (write) {
		*data = readl(&(__dw_regs(dw)->wr_cnt_msb));
		*data <<= 32;
		*data |= readl(&(__dw_regs(dw)->wr_cnt_lsb));
	} else {
		*data = readl(&(__dw_regs(dw)->rd_cnt_msb));
		*data <<= 32;
		*data |= readl(&(__dw_regs(dw)->rd_cnt_lsb));
	}
}

static u64 dw_xdata_perf_diff(u64 *m1, u64 *m2, u64 time)
{
	u64 rate = (*m1 - *m2);

	rate *= (1000 * 1000 * 1000);
	rate >>= 20;
	rate = DIV_ROUND_CLOSEST_ULL(rate, time);

	return rate;
}

static void dw_xdata_perf(struct dw_xdata *dw, u64 *rate, bool write)
{
	struct device *dev = &dw->pdev->dev;
	u64 data[2], time[2], diff;

	mutex_lock(&dw->mutex);

	/* First acquisition of current count frames */
	writel(0x0, &(__dw_regs(dw)->perf_control));
	dw_xdata_perf_meas(dw, &data[0], write);
	time[0] = jiffies;
	writel((u32)XPERF_CONTROL_ENABLE, &(__dw_regs(dw)->perf_control));

	/*
	 * Wait 100ms between the 1st count frame acquisition and the 2nd
	 * count frame acquisition, in order to calculate the speed later
	 */
	mdelay(100);

	/* Second acquisition of current count frames */
	writel(0x0, &(__dw_regs(dw)->perf_control));
	dw_xdata_perf_meas(dw, &data[1], write);
	time[1] = jiffies;
	writel((u32)XPERF_CONTROL_ENABLE, &(__dw_regs(dw)->perf_control));

	/*
	 * Speed calculation
	 *
	 * rate = (2nd count frames - 1st count frames) / (time elapsed)
	 */
	diff = jiffies_to_nsecs(time[1] - time[0]);
	*rate = dw_xdata_perf_diff(&data[1], &data[0], diff);

	mutex_unlock(&dw->mutex);

	dev_dbg(dev, "xData: time=%llu us, %s=%llu MB/s\n",
		diff, write ? "write" : "read", *rate);
}

static struct dw_xdata *misc_dev_to_dw(struct miscdevice *misc_dev)
{
	return container_of(misc_dev, struct dw_xdata, misc_dev);
}

static ssize_t write_show(struct device *dev, struct device_attribute *attr,
			  char *buf)
{
	struct miscdevice *misc_dev = dev_get_drvdata(dev);
	struct dw_xdata *dw = misc_dev_to_dw(misc_dev);
	u64 rate;

	dw_xdata_perf(dw, &rate, true);

	return sysfs_emit(buf, "%llu\n", rate);
}

static ssize_t write_store(struct device *dev, struct device_attribute *attr,
			   const char *buf, size_t size)
{
	struct miscdevice *misc_dev = dev_get_drvdata(dev);
	struct dw_xdata *dw = misc_dev_to_dw(misc_dev);
	bool enabled;
	int ret;

	ret = kstrtobool(buf, &enabled);
	if (ret < 0)
		return ret;

	if (enabled) {
		dev_dbg(dev, "xData: requested write transfer\n");
		dw_xdata_start(dw, true);
	} else {
		dev_dbg(dev, "xData: requested stop transfer\n");
		dw_xdata_stop(dw);
	}

	return size;
}

static DEVICE_ATTR_RW(write);

static ssize_t read_show(struct device *dev, struct device_attribute *attr,
			 char *buf)
{
	struct miscdevice *misc_dev = dev_get_drvdata(dev);
	struct dw_xdata *dw = misc_dev_to_dw(misc_dev);
	u64 rate;

	dw_xdata_perf(dw, &rate, false);

	return sysfs_emit(buf, "%llu\n", rate);
}

static ssize_t read_store(struct device *dev, struct device_attribute *attr,
			  const char *buf, size_t size)
{
	struct miscdevice *misc_dev = dev_get_drvdata(dev);
	struct dw_xdata *dw = misc_dev_to_dw(misc_dev);
	bool enabled;
	int ret;

	ret = kstrtobool(buf, &enabled);
	if (ret < 0)
		return ret;

	if (enabled) {
		dev_dbg(dev, "xData: requested read transfer\n");
		dw_xdata_start(dw, false);
	} else {
		dev_dbg(dev, "xData: requested stop transfer\n");
		dw_xdata_stop(dw);
	}

	return size;
}

static DEVICE_ATTR_RW(read);

static struct attribute *xdata_attrs[] = {
	&dev_attr_write.attr,
	&dev_attr_read.attr,
	NULL,
};

ATTRIBUTE_GROUPS(xdata);

static int dw_xdata_pcie_probe(struct pci_dev *pdev,
			       const struct pci_device_id *pid)
{
	struct device *dev = &pdev->dev;
	struct dw_xdata *dw;
	char name[24];
	u64 addr;
	int err;
	int id;

	/* Enable PCI device */
	err = pcim_enable_device(pdev);
	if (err) {
		dev_err(dev, "enabling device failed\n");
		return err;
	}

	/* Mapping PCI BAR regions */
	err = pcim_iomap_regions(pdev, BIT(BAR_0), pci_name(pdev));
	if (err) {
		dev_err(dev, "xData BAR I/O remapping failed\n");
		return err;
	}

	pci_set_master(pdev);

	/* Allocate memory */
	dw = devm_kzalloc(dev, sizeof(*dw), GFP_KERNEL);
	if (!dw)
		return -ENOMEM;

	/* Data structure initialization */
	mutex_init(&dw->mutex);

	dw->rg_region.vaddr = pcim_iomap_table(pdev)[BAR_0];
	if (!dw->rg_region.vaddr)
		return -ENOMEM;

	dw->rg_region.paddr = pdev->resource[BAR_0].start;

	dw->max_wr_len = pcie_get_mps(pdev);
	dw->max_wr_len >>= 2;

	dw->max_rd_len = pcie_get_readrq(pdev);
	dw->max_rd_len >>= 2;

	dw->pdev = pdev;

	id = ida_alloc(&xdata_ida, GFP_KERNEL);
	if (id < 0) {
		dev_err(dev, "xData: unable to get id\n");
		return id;
	}

	snprintf(name, sizeof(name), DW_XDATA_DRIVER_NAME ".%d", id);
	dw->misc_dev.name = kstrdup(name, GFP_KERNEL);
	if (!dw->misc_dev.name) {
		err = -ENOMEM;
		goto err_ida_remove;
	}

	dw->misc_dev.minor = MISC_DYNAMIC_MINOR;
	dw->misc_dev.parent = dev;
	dw->misc_dev.groups = xdata_groups;

	writel(0x0, &(__dw_regs(dw)->RAM_addr));
	writel(0x0, &(__dw_regs(dw)->RAM_port));

	addr = dw->rg_region.paddr + DW_XDATA_EP_MEM_OFFSET;
	writel(lower_32_bits(addr), &(__dw_regs(dw)->addr_lsb));
	writel(upper_32_bits(addr), &(__dw_regs(dw)->addr_msb));
	dev_dbg(dev, "xData: target address = 0x%.16llx\n", addr);

	dev_dbg(dev, "xData: wr_len = %zu, rd_len = %zu\n",
		dw->max_wr_len * 4, dw->max_rd_len * 4);

	/* Saving data structure reference */
	pci_set_drvdata(pdev, dw);

	/* Register misc device */
	err = misc_register(&dw->misc_dev);
	if (err) {
		dev_err(dev, "xData: failed to register device\n");
		goto err_kfree_name;
	}

	return 0;

err_kfree_name:
	kfree(dw->misc_dev.name);

err_ida_remove:
	ida_free(&xdata_ida, id);

	return err;
}

static void dw_xdata_pcie_remove(struct pci_dev *pdev)
{
	struct dw_xdata *dw = pci_get_drvdata(pdev);
	int id;

	if (sscanf(dw->misc_dev.name, DW_XDATA_DRIVER_NAME ".%d", &id) != 1)
		return;

	if (id < 0)
		return;

	dw_xdata_stop(dw);
	misc_deregister(&dw->misc_dev);
	kfree(dw->misc_dev.name);
	ida_free(&xdata_ida, id);
}

static const struct pci_device_id dw_xdata_pcie_id_table[] = {
	{ PCI_DEVICE_DATA(SYNOPSYS, EDDA, NULL) },
	{ }
};
MODULE_DEVICE_TABLE(pci, dw_xdata_pcie_id_table);

static struct pci_driver dw_xdata_pcie_driver = {
	.name		= DW_XDATA_DRIVER_NAME,
	.id_table	= dw_xdata_pcie_id_table,
	.probe		= dw_xdata_pcie_probe,
	.remove		= dw_xdata_pcie_remove,
};

module_pci_driver(dw_xdata_pcie_driver);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Synopsys DesignWare xData PCIe driver");
MODULE_AUTHOR("Gustavo Pimentel <gustavo.pimentel@synopsys.com>");