/**
 * Host side test driver to test endpoint functionality
 *
 * Copyright (C) 2017 Texas Instruments
 * Author: Kishon Vijay Abraham I <kishon@ti.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 of
 * the License as published by the Free Software Foundation.
 *
 * 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/crc32.h>
#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/pci.h>
#include <linux/pci_ids.h>

#include <linux/pci_regs.h>

#include <uapi/linux/pcitest.h>

#define DRV_MODULE_NAME			"pci-endpoint-test"

#define PCI_ENDPOINT_TEST_MAGIC		0x0

#define PCI_ENDPOINT_TEST_COMMAND	0x4
#define COMMAND_RAISE_LEGACY_IRQ	BIT(0)
#define COMMAND_RAISE_MSI_IRQ		BIT(1)
#define MSI_NUMBER_SHIFT		2
/* 6 bits for MSI number */
#define COMMAND_READ                    BIT(8)
#define COMMAND_WRITE                   BIT(9)
#define COMMAND_COPY                    BIT(10)

#define PCI_ENDPOINT_TEST_STATUS	0x8
#define STATUS_READ_SUCCESS             BIT(0)
#define STATUS_READ_FAIL                BIT(1)
#define STATUS_WRITE_SUCCESS            BIT(2)
#define STATUS_WRITE_FAIL               BIT(3)
#define STATUS_COPY_SUCCESS             BIT(4)
#define STATUS_COPY_FAIL                BIT(5)
#define STATUS_IRQ_RAISED               BIT(6)
#define STATUS_SRC_ADDR_INVALID         BIT(7)
#define STATUS_DST_ADDR_INVALID         BIT(8)

#define PCI_ENDPOINT_TEST_LOWER_SRC_ADDR	0xc
#define PCI_ENDPOINT_TEST_UPPER_SRC_ADDR	0x10

#define PCI_ENDPOINT_TEST_LOWER_DST_ADDR	0x14
#define PCI_ENDPOINT_TEST_UPPER_DST_ADDR	0x18

#define PCI_ENDPOINT_TEST_SIZE		0x1c
#define PCI_ENDPOINT_TEST_CHECKSUM	0x20

static DEFINE_IDA(pci_endpoint_test_ida);

#define to_endpoint_test(priv) container_of((priv), struct pci_endpoint_test, \
					    miscdev)

static bool no_msi;
module_param(no_msi, bool, 0444);
MODULE_PARM_DESC(no_msi, "Disable MSI interrupt in pci_endpoint_test");

enum pci_barno {
	BAR_0,
	BAR_1,
	BAR_2,
	BAR_3,
	BAR_4,
	BAR_5,
};

struct pci_endpoint_test {
	struct pci_dev	*pdev;
	void __iomem	*base;
	void __iomem	*bar[6];
	struct completion irq_raised;
	int		last_irq;
	int		num_irqs;
	/* mutex to protect the ioctls */
	struct mutex	mutex;
	struct miscdevice miscdev;
	enum pci_barno test_reg_bar;
	size_t alignment;
};

struct pci_endpoint_test_data {
	enum pci_barno test_reg_bar;
	size_t alignment;
	bool no_msi;
};

static inline u32 pci_endpoint_test_readl(struct pci_endpoint_test *test,
					  u32 offset)
{
	return readl(test->base + offset);
}

static inline void pci_endpoint_test_writel(struct pci_endpoint_test *test,
					    u32 offset, u32 value)
{
	writel(value, test->base + offset);
}

static inline u32 pci_endpoint_test_bar_readl(struct pci_endpoint_test *test,
					      int bar, int offset)
{
	return readl(test->bar[bar] + offset);
}

static inline void pci_endpoint_test_bar_writel(struct pci_endpoint_test *test,
						int bar, u32 offset, u32 value)
{
	writel(value, test->bar[bar] + offset);
}

static irqreturn_t pci_endpoint_test_irqhandler(int irq, void *dev_id)
{
	struct pci_endpoint_test *test = dev_id;
	u32 reg;

	reg = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_STATUS);
	if (reg & STATUS_IRQ_RAISED) {
		test->last_irq = irq;
		complete(&test->irq_raised);
		reg &= ~STATUS_IRQ_RAISED;
	}
	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_STATUS,
				 reg);

	return IRQ_HANDLED;
}

static bool pci_endpoint_test_bar(struct pci_endpoint_test *test,
				  enum pci_barno barno)
{
	int j;
	u32 val;
	int size;
	struct pci_dev *pdev = test->pdev;

	if (!test->bar[barno])
		return false;

	size = pci_resource_len(pdev, barno);

	if (barno == test->test_reg_bar)
		size = 0x4;

	for (j = 0; j < size; j += 4)
		pci_endpoint_test_bar_writel(test, barno, j, 0xA0A0A0A0);

	for (j = 0; j < size; j += 4) {
		val = pci_endpoint_test_bar_readl(test, barno, j);
		if (val != 0xA0A0A0A0)
			return false;
	}

	return true;
}

static bool pci_endpoint_test_legacy_irq(struct pci_endpoint_test *test)
{
	u32 val;

	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_COMMAND,
				 COMMAND_RAISE_LEGACY_IRQ);
	val = wait_for_completion_timeout(&test->irq_raised,
					  msecs_to_jiffies(1000));
	if (!val)
		return false;

	return true;
}

static bool pci_endpoint_test_msi_irq(struct pci_endpoint_test *test,
				      u8 msi_num)
{
	u32 val;
	struct pci_dev *pdev = test->pdev;

	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_COMMAND,
				 msi_num << MSI_NUMBER_SHIFT |
				 COMMAND_RAISE_MSI_IRQ);
	val = wait_for_completion_timeout(&test->irq_raised,
					  msecs_to_jiffies(1000));
	if (!val)
		return false;

	if (test->last_irq - pdev->irq == msi_num - 1)
		return true;

	return false;
}

static bool pci_endpoint_test_copy(struct pci_endpoint_test *test, size_t size)
{
	bool ret = false;
	void *src_addr;
	void *dst_addr;
	dma_addr_t src_phys_addr;
	dma_addr_t dst_phys_addr;
	struct pci_dev *pdev = test->pdev;
	struct device *dev = &pdev->dev;
	void *orig_src_addr;
	dma_addr_t orig_src_phys_addr;
	void *orig_dst_addr;
	dma_addr_t orig_dst_phys_addr;
	size_t offset;
	size_t alignment = test->alignment;
	u32 src_crc32;
	u32 dst_crc32;

	if (size > SIZE_MAX - alignment)
		goto err;

	orig_src_addr = dma_alloc_coherent(dev, size + alignment,
					   &orig_src_phys_addr, GFP_KERNEL);
	if (!orig_src_addr) {
		dev_err(dev, "failed to allocate source buffer\n");
		ret = false;
		goto err;
	}

	if (alignment && !IS_ALIGNED(orig_src_phys_addr, alignment)) {
		src_phys_addr = PTR_ALIGN(orig_src_phys_addr, alignment);
		offset = src_phys_addr - orig_src_phys_addr;
		src_addr = orig_src_addr + offset;
	} else {
		src_phys_addr = orig_src_phys_addr;
		src_addr = orig_src_addr;
	}

	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_LOWER_SRC_ADDR,
				 lower_32_bits(src_phys_addr));

	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_UPPER_SRC_ADDR,
				 upper_32_bits(src_phys_addr));

	get_random_bytes(src_addr, size);
	src_crc32 = crc32_le(~0, src_addr, size);

	orig_dst_addr = dma_alloc_coherent(dev, size + alignment,
					   &orig_dst_phys_addr, GFP_KERNEL);
	if (!orig_dst_addr) {
		dev_err(dev, "failed to allocate destination address\n");
		ret = false;
		goto err_orig_src_addr;
	}

	if (alignment && !IS_ALIGNED(orig_dst_phys_addr, alignment)) {
		dst_phys_addr = PTR_ALIGN(orig_dst_phys_addr, alignment);
		offset = dst_phys_addr - orig_dst_phys_addr;
		dst_addr = orig_dst_addr + offset;
	} else {
		dst_phys_addr = orig_dst_phys_addr;
		dst_addr = orig_dst_addr;
	}

	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_LOWER_DST_ADDR,
				 lower_32_bits(dst_phys_addr));
	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_UPPER_DST_ADDR,
				 upper_32_bits(dst_phys_addr));

	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_SIZE,
				 size);

	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_COMMAND,
				 1 << MSI_NUMBER_SHIFT | COMMAND_COPY);

	wait_for_completion(&test->irq_raised);

	dst_crc32 = crc32_le(~0, dst_addr, size);
	if (dst_crc32 == src_crc32)
		ret = true;

	dma_free_coherent(dev, size + alignment, orig_dst_addr,
			  orig_dst_phys_addr);

err_orig_src_addr:
	dma_free_coherent(dev, size + alignment, orig_src_addr,
			  orig_src_phys_addr);

err:
	return ret;
}

static bool pci_endpoint_test_write(struct pci_endpoint_test *test, size_t size)
{
	bool ret = false;
	u32 reg;
	void *addr;
	dma_addr_t phys_addr;
	struct pci_dev *pdev = test->pdev;
	struct device *dev = &pdev->dev;
	void *orig_addr;
	dma_addr_t orig_phys_addr;
	size_t offset;
	size_t alignment = test->alignment;
	u32 crc32;

	if (size > SIZE_MAX - alignment)
		goto err;

	orig_addr = dma_alloc_coherent(dev, size + alignment, &orig_phys_addr,
				       GFP_KERNEL);
	if (!orig_addr) {
		dev_err(dev, "failed to allocate address\n");
		ret = false;
		goto err;
	}

	if (alignment && !IS_ALIGNED(orig_phys_addr, alignment)) {
		phys_addr =  PTR_ALIGN(orig_phys_addr, alignment);
		offset = phys_addr - orig_phys_addr;
		addr = orig_addr + offset;
	} else {
		phys_addr = orig_phys_addr;
		addr = orig_addr;
	}

	get_random_bytes(addr, size);

	crc32 = crc32_le(~0, addr, size);
	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_CHECKSUM,
				 crc32);

	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_LOWER_SRC_ADDR,
				 lower_32_bits(phys_addr));
	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_UPPER_SRC_ADDR,
				 upper_32_bits(phys_addr));

	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_SIZE, size);

	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_COMMAND,
				 1 << MSI_NUMBER_SHIFT | COMMAND_READ);

	wait_for_completion(&test->irq_raised);

	reg = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_STATUS);
	if (reg & STATUS_READ_SUCCESS)
		ret = true;

	dma_free_coherent(dev, size + alignment, orig_addr, orig_phys_addr);

err:
	return ret;
}

static bool pci_endpoint_test_read(struct pci_endpoint_test *test, size_t size)
{
	bool ret = false;
	void *addr;
	dma_addr_t phys_addr;
	struct pci_dev *pdev = test->pdev;
	struct device *dev = &pdev->dev;
	void *orig_addr;
	dma_addr_t orig_phys_addr;
	size_t offset;
	size_t alignment = test->alignment;
	u32 crc32;

	if (size > SIZE_MAX - alignment)
		goto err;

	orig_addr = dma_alloc_coherent(dev, size + alignment, &orig_phys_addr,
				       GFP_KERNEL);
	if (!orig_addr) {
		dev_err(dev, "failed to allocate destination address\n");
		ret = false;
		goto err;
	}

	if (alignment && !IS_ALIGNED(orig_phys_addr, alignment)) {
		phys_addr = PTR_ALIGN(orig_phys_addr, alignment);
		offset = phys_addr - orig_phys_addr;
		addr = orig_addr + offset;
	} else {
		phys_addr = orig_phys_addr;
		addr = orig_addr;
	}

	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_LOWER_DST_ADDR,
				 lower_32_bits(phys_addr));
	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_UPPER_DST_ADDR,
				 upper_32_bits(phys_addr));

	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_SIZE, size);

	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_COMMAND,
				 1 << MSI_NUMBER_SHIFT | COMMAND_WRITE);

	wait_for_completion(&test->irq_raised);

	crc32 = crc32_le(~0, addr, size);
	if (crc32 == pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_CHECKSUM))
		ret = true;

	dma_free_coherent(dev, size + alignment, orig_addr, orig_phys_addr);
err:
	return ret;
}

static long pci_endpoint_test_ioctl(struct file *file, unsigned int cmd,
				    unsigned long arg)
{
	int ret = -EINVAL;
	enum pci_barno bar;
	struct pci_endpoint_test *test = to_endpoint_test(file->private_data);

	mutex_lock(&test->mutex);
	switch (cmd) {
	case PCITEST_BAR:
		bar = arg;
		if (bar < 0 || bar > 5)
			goto ret;
		ret = pci_endpoint_test_bar(test, bar);
		break;
	case PCITEST_LEGACY_IRQ:
		ret = pci_endpoint_test_legacy_irq(test);
		break;
	case PCITEST_MSI:
		ret = pci_endpoint_test_msi_irq(test, arg);
		break;
	case PCITEST_WRITE:
		ret = pci_endpoint_test_write(test, arg);
		break;
	case PCITEST_READ:
		ret = pci_endpoint_test_read(test, arg);
		break;
	case PCITEST_COPY:
		ret = pci_endpoint_test_copy(test, arg);
		break;
	}

ret:
	mutex_unlock(&test->mutex);
	return ret;
}

static const struct file_operations pci_endpoint_test_fops = {
	.owner = THIS_MODULE,
	.unlocked_ioctl = pci_endpoint_test_ioctl,
};

static int pci_endpoint_test_probe(struct pci_dev *pdev,
				   const struct pci_device_id *ent)
{
	int i;
	int err;
	int irq = 0;
	int id;
	char name[24];
	enum pci_barno bar;
	void __iomem *base;
	struct device *dev = &pdev->dev;
	struct pci_endpoint_test *test;
	struct pci_endpoint_test_data *data;
	enum pci_barno test_reg_bar = BAR_0;
	struct miscdevice *misc_device;

	if (pci_is_bridge(pdev))
		return -ENODEV;

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

	test->test_reg_bar = 0;
	test->alignment = 0;
	test->pdev = pdev;

	data = (struct pci_endpoint_test_data *)ent->driver_data;
	if (data) {
		test_reg_bar = data->test_reg_bar;
		test->test_reg_bar = test_reg_bar;
		test->alignment = data->alignment;
		no_msi = data->no_msi;
	}

	init_completion(&test->irq_raised);
	mutex_init(&test->mutex);

	err = pci_enable_device(pdev);
	if (err) {
		dev_err(dev, "Cannot enable PCI device\n");
		return err;
	}

	err = pci_request_regions(pdev, DRV_MODULE_NAME);
	if (err) {
		dev_err(dev, "Cannot obtain PCI resources\n");
		goto err_disable_pdev;
	}

	pci_set_master(pdev);

	if (!no_msi) {
		irq = pci_alloc_irq_vectors(pdev, 1, 32, PCI_IRQ_MSI);
		if (irq < 0)
			dev_err(dev, "failed to get MSI interrupts\n");
		test->num_irqs = irq;
	}

	err = devm_request_irq(dev, pdev->irq, pci_endpoint_test_irqhandler,
			       IRQF_SHARED, DRV_MODULE_NAME, test);
	if (err) {
		dev_err(dev, "failed to request IRQ %d\n", pdev->irq);
		goto err_disable_msi;
	}

	for (i = 1; i < irq; i++) {
		err = devm_request_irq(dev, pdev->irq + i,
				       pci_endpoint_test_irqhandler,
				       IRQF_SHARED, DRV_MODULE_NAME, test);
		if (err)
			dev_err(dev, "failed to request IRQ %d for MSI %d\n",
				pdev->irq + i, i + 1);
	}

	for (bar = BAR_0; bar <= BAR_5; bar++) {
		base = pci_ioremap_bar(pdev, bar);
		if (!base) {
			dev_err(dev, "failed to read BAR%d\n", bar);
			WARN_ON(bar == test_reg_bar);
		}
		test->bar[bar] = base;
	}

	test->base = test->bar[test_reg_bar];
	if (!test->base) {
		err = -ENOMEM;
		dev_err(dev, "Cannot perform PCI test without BAR%d\n",
			test_reg_bar);
		goto err_iounmap;
	}

	pci_set_drvdata(pdev, test);

	id = ida_simple_get(&pci_endpoint_test_ida, 0, 0, GFP_KERNEL);
	if (id < 0) {
		err = id;
		dev_err(dev, "unable to get id\n");
		goto err_iounmap;
	}

	snprintf(name, sizeof(name), DRV_MODULE_NAME ".%d", id);
	misc_device = &test->miscdev;
	misc_device->minor = MISC_DYNAMIC_MINOR;
	misc_device->name = name;
	misc_device->fops = &pci_endpoint_test_fops,

	err = misc_register(misc_device);
	if (err) {
		dev_err(dev, "failed to register device\n");
		goto err_ida_remove;
	}

	return 0;

err_ida_remove:
	ida_simple_remove(&pci_endpoint_test_ida, id);

err_iounmap:
	for (bar = BAR_0; bar <= BAR_5; bar++) {
		if (test->bar[bar])
			pci_iounmap(pdev, test->bar[bar]);
	}

	for (i = 0; i < irq; i++)
		devm_free_irq(dev, pdev->irq + i, test);

err_disable_msi:
	pci_disable_msi(pdev);
	pci_release_regions(pdev);

err_disable_pdev:
	pci_disable_device(pdev);

	return err;
}

static void pci_endpoint_test_remove(struct pci_dev *pdev)
{
	int id;
	int i;
	enum pci_barno bar;
	struct pci_endpoint_test *test = pci_get_drvdata(pdev);
	struct miscdevice *misc_device = &test->miscdev;

	if (sscanf(misc_device->name, DRV_MODULE_NAME ".%d", &id) != 1)
		return;
	if (id < 0)
		return;

	misc_deregister(&test->miscdev);
	ida_simple_remove(&pci_endpoint_test_ida, id);
	for (bar = BAR_0; bar <= BAR_5; bar++) {
		if (test->bar[bar])
			pci_iounmap(pdev, test->bar[bar]);
	}
	for (i = 0; i < test->num_irqs; i++)
		devm_free_irq(&pdev->dev, pdev->irq + i, test);
	pci_disable_msi(pdev);
	pci_release_regions(pdev);
	pci_disable_device(pdev);
}

static const struct pci_device_id pci_endpoint_test_tbl[] = {
	{ PCI_DEVICE(PCI_VENDOR_ID_TI, PCI_DEVICE_ID_TI_DRA74x) },
	{ PCI_DEVICE(PCI_VENDOR_ID_TI, PCI_DEVICE_ID_TI_DRA72x) },
	{ }
};
MODULE_DEVICE_TABLE(pci, pci_endpoint_test_tbl);

static struct pci_driver pci_endpoint_test_driver = {
	.name		= DRV_MODULE_NAME,
	.id_table	= pci_endpoint_test_tbl,
	.probe		= pci_endpoint_test_probe,
	.remove		= pci_endpoint_test_remove,
};
module_pci_driver(pci_endpoint_test_driver);

MODULE_DESCRIPTION("PCI ENDPOINT TEST HOST DRIVER");
MODULE_AUTHOR("Kishon Vijay Abraham I <kishon@ti.com>");
MODULE_LICENSE("GPL v2");