// SPDX-License-Identifier: (GPL-2.0 OR MIT)
/*
 * Siemens System Memory Buffer driver.
 * Copyright(c) 2022, HiSilicon Limited.
 */

#include <linux/atomic.h>
#include <linux/acpi.h>
#include <linux/circ_buf.h>
#include <linux/err.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/platform_device.h>

#include "coresight-etm-perf.h"
#include "coresight-priv.h"
#include "ultrasoc-smb.h"

DEFINE_CORESIGHT_DEVLIST(sink_devs, "ultra_smb");

#define ULTRASOC_SMB_DSM_UUID	"82ae1283-7f6a-4cbe-aa06-53e8fb24db18"

static bool smb_buffer_not_empty(struct smb_drv_data *drvdata)
{
	u32 buf_status = readl(drvdata->base + SMB_LB_INT_STS_REG);

	return FIELD_GET(SMB_LB_INT_STS_NOT_EMPTY_MSK, buf_status);
}

static void smb_update_data_size(struct smb_drv_data *drvdata)
{
	struct smb_data_buffer *sdb = &drvdata->sdb;
	u32 buf_wrptr;

	buf_wrptr = readl(drvdata->base + SMB_LB_WR_ADDR_REG) -
			  sdb->buf_hw_base;

	/* Buffer is full */
	if (buf_wrptr == sdb->buf_rdptr && smb_buffer_not_empty(drvdata)) {
		sdb->data_size = sdb->buf_size;
		return;
	}

	/* The buffer mode is circular buffer mode */
	sdb->data_size = CIRC_CNT(buf_wrptr, sdb->buf_rdptr,
				  sdb->buf_size);
}

/*
 * The read pointer adds @nbytes bytes (may round up to the beginning)
 * after the data is read or discarded, while needing to update the
 * available data size.
 */
static void smb_update_read_ptr(struct smb_drv_data *drvdata, u32 nbytes)
{
	struct smb_data_buffer *sdb = &drvdata->sdb;

	sdb->buf_rdptr += nbytes;
	sdb->buf_rdptr %= sdb->buf_size;
	writel(sdb->buf_hw_base + sdb->buf_rdptr,
	       drvdata->base + SMB_LB_RD_ADDR_REG);

	sdb->data_size -= nbytes;
}

static void smb_reset_buffer(struct smb_drv_data *drvdata)
{
	struct smb_data_buffer *sdb = &drvdata->sdb;
	u32 write_ptr;

	/*
	 * We must flush and discard any data left in hardware path
	 * to avoid corrupting the next session.
	 * Note: The write pointer will never exceed the read pointer.
	 */
	writel(SMB_LB_PURGE_PURGED, drvdata->base + SMB_LB_PURGE_REG);

	/* Reset SMB logical buffer status flags */
	writel(SMB_LB_INT_STS_RESET, drvdata->base + SMB_LB_INT_STS_REG);

	write_ptr = readl(drvdata->base + SMB_LB_WR_ADDR_REG);

	/* Do nothing, not data left in hardware path */
	if (!write_ptr || write_ptr == sdb->buf_rdptr + sdb->buf_hw_base)
		return;

	/*
	 * The SMB_LB_WR_ADDR_REG register is read-only,
	 * Synchronize the read pointer to write pointer.
	 */
	writel(write_ptr, drvdata->base + SMB_LB_RD_ADDR_REG);
	sdb->buf_rdptr = write_ptr - sdb->buf_hw_base;
}

static int smb_open(struct inode *inode, struct file *file)
{
	struct smb_drv_data *drvdata = container_of(file->private_data,
					struct smb_drv_data, miscdev);

	guard(spinlock)(&drvdata->spinlock);

	if (drvdata->reading)
		return -EBUSY;

	if (drvdata->csdev->refcnt)
		return -EBUSY;

	smb_update_data_size(drvdata);
	drvdata->reading = true;

	return 0;
}

static ssize_t smb_read(struct file *file, char __user *data, size_t len,
			loff_t *ppos)
{
	struct smb_drv_data *drvdata = container_of(file->private_data,
					struct smb_drv_data, miscdev);
	struct smb_data_buffer *sdb = &drvdata->sdb;
	struct device *dev = &drvdata->csdev->dev;
	ssize_t to_copy = 0;

	if (!len)
		return 0;

	if (!sdb->data_size)
		return 0;

	to_copy = min(sdb->data_size, len);

	/* Copy parts of trace data when read pointer wrap around SMB buffer */
	if (sdb->buf_rdptr + to_copy > sdb->buf_size)
		to_copy = sdb->buf_size - sdb->buf_rdptr;

	if (copy_to_user(data, sdb->buf_base + sdb->buf_rdptr, to_copy)) {
		dev_dbg(dev, "Failed to copy data to user\n");
		return -EFAULT;
	}

	*ppos += to_copy;
	smb_update_read_ptr(drvdata, to_copy);
	if (!sdb->data_size)
		smb_reset_buffer(drvdata);

	dev_dbg(dev, "%zu bytes copied\n", to_copy);
	return to_copy;
}

static int smb_release(struct inode *inode, struct file *file)
{
	struct smb_drv_data *drvdata = container_of(file->private_data,
					struct smb_drv_data, miscdev);

	guard(spinlock)(&drvdata->spinlock);
	drvdata->reading = false;

	return 0;
}

static const struct file_operations smb_fops = {
	.owner		= THIS_MODULE,
	.open		= smb_open,
	.read		= smb_read,
	.release	= smb_release,
	.llseek		= no_llseek,
};

static ssize_t buf_size_show(struct device *dev, struct device_attribute *attr,
			     char *buf)
{
	struct smb_drv_data *drvdata = dev_get_drvdata(dev->parent);

	return sysfs_emit(buf, "0x%lx\n", drvdata->sdb.buf_size);
}
static DEVICE_ATTR_RO(buf_size);

static struct attribute *smb_sink_attrs[] = {
	coresight_simple_reg32(read_pos, SMB_LB_RD_ADDR_REG),
	coresight_simple_reg32(write_pos, SMB_LB_WR_ADDR_REG),
	coresight_simple_reg32(buf_status, SMB_LB_INT_STS_REG),
	&dev_attr_buf_size.attr,
	NULL
};

static const struct attribute_group smb_sink_group = {
	.attrs = smb_sink_attrs,
	.name = "mgmt",
};

static const struct attribute_group *smb_sink_groups[] = {
	&smb_sink_group,
	NULL
};

static void smb_enable_hw(struct smb_drv_data *drvdata)
{
	writel(SMB_GLB_EN_HW_ENABLE, drvdata->base + SMB_GLB_EN_REG);
}

static void smb_disable_hw(struct smb_drv_data *drvdata)
{
	writel(0x0, drvdata->base + SMB_GLB_EN_REG);
}

static void smb_enable_sysfs(struct coresight_device *csdev)
{
	struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);

	if (coresight_get_mode(csdev) != CS_MODE_DISABLED)
		return;

	smb_enable_hw(drvdata);
	coresight_set_mode(csdev, CS_MODE_SYSFS);
}

static int smb_enable_perf(struct coresight_device *csdev, void *data)
{
	struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);
	struct perf_output_handle *handle = data;
	struct cs_buffers *buf = etm_perf_sink_config(handle);
	pid_t pid;

	if (!buf)
		return -EINVAL;

	/* Get a handle on the pid of the target process */
	pid = buf->pid;

	/* Device is already in used by other session */
	if (drvdata->pid != -1 && drvdata->pid != pid)
		return -EBUSY;

	if (drvdata->pid == -1) {
		smb_enable_hw(drvdata);
		drvdata->pid = pid;
		coresight_set_mode(csdev, CS_MODE_PERF);
	}

	return 0;
}

static int smb_enable(struct coresight_device *csdev, enum cs_mode mode,
		      void *data)
{
	struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);
	int ret = 0;

	guard(spinlock)(&drvdata->spinlock);

	/* Do nothing, the trace data is reading by other interface now */
	if (drvdata->reading)
		return -EBUSY;

	/* Do nothing, the SMB is already enabled as other mode */
	if (coresight_get_mode(csdev) != CS_MODE_DISABLED &&
	    coresight_get_mode(csdev) != mode)
		return -EBUSY;

	switch (mode) {
	case CS_MODE_SYSFS:
		smb_enable_sysfs(csdev);
		break;
	case CS_MODE_PERF:
		ret = smb_enable_perf(csdev, data);
		break;
	default:
		ret = -EINVAL;
	}

	if (ret)
		return ret;

	csdev->refcnt++;
	dev_dbg(&csdev->dev, "Ultrasoc SMB enabled\n");

	return ret;
}

static int smb_disable(struct coresight_device *csdev)
{
	struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);

	guard(spinlock)(&drvdata->spinlock);

	if (drvdata->reading)
		return -EBUSY;

	csdev->refcnt--;
	if (csdev->refcnt)
		return -EBUSY;

	/* Complain if we (somehow) got out of sync */
	WARN_ON_ONCE(coresight_get_mode(csdev) == CS_MODE_DISABLED);

	smb_disable_hw(drvdata);

	/* Dissociate from the target process. */
	drvdata->pid = -1;
	coresight_set_mode(csdev, CS_MODE_DISABLED);
	dev_dbg(&csdev->dev, "Ultrasoc SMB disabled\n");

	return 0;
}

static void *smb_alloc_buffer(struct coresight_device *csdev,
			      struct perf_event *event, void **pages,
			      int nr_pages, bool overwrite)
{
	struct cs_buffers *buf;
	int node;

	node = (event->cpu == -1) ? NUMA_NO_NODE : cpu_to_node(event->cpu);
	buf = kzalloc_node(sizeof(struct cs_buffers), GFP_KERNEL, node);
	if (!buf)
		return NULL;

	buf->snapshot = overwrite;
	buf->nr_pages = nr_pages;
	buf->data_pages = pages;
	buf->pid = task_pid_nr(event->owner);

	return buf;
}

static void smb_free_buffer(void *config)
{
	struct cs_buffers *buf = config;

	kfree(buf);
}

static void smb_sync_perf_buffer(struct smb_drv_data *drvdata,
				 struct cs_buffers *buf,
				 unsigned long head)
{
	struct smb_data_buffer *sdb = &drvdata->sdb;
	char **dst_pages = (char **)buf->data_pages;
	unsigned long to_copy;
	long pg_idx, pg_offset;

	pg_idx = head >> PAGE_SHIFT;
	pg_offset = head & (PAGE_SIZE - 1);

	while (sdb->data_size) {
		unsigned long pg_space = PAGE_SIZE - pg_offset;

		to_copy = min(sdb->data_size, pg_space);

		/* Copy parts of trace data when read pointer wrap around */
		if (sdb->buf_rdptr + to_copy > sdb->buf_size)
			to_copy = sdb->buf_size - sdb->buf_rdptr;

		memcpy(dst_pages[pg_idx] + pg_offset,
			      sdb->buf_base + sdb->buf_rdptr, to_copy);

		pg_offset += to_copy;
		if (pg_offset >= PAGE_SIZE) {
			pg_offset = 0;
			pg_idx++;
			pg_idx %= buf->nr_pages;
		}
		smb_update_read_ptr(drvdata, to_copy);
	}

	smb_reset_buffer(drvdata);
}

static unsigned long smb_update_buffer(struct coresight_device *csdev,
				       struct perf_output_handle *handle,
				       void *sink_config)
{
	struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);
	struct smb_data_buffer *sdb = &drvdata->sdb;
	struct cs_buffers *buf = sink_config;
	unsigned long data_size;
	bool lost = false;

	if (!buf)
		return 0;

	guard(spinlock)(&drvdata->spinlock);

	/* Don't do anything if another tracer is using this sink. */
	if (csdev->refcnt != 1)
		return 0;

	smb_disable_hw(drvdata);
	smb_update_data_size(drvdata);

	/*
	 * The SMB buffer may be bigger than the space available in the
	 * perf ring buffer (handle->size). If so advance the offset so
	 * that we get the latest trace data.
	 */
	if (sdb->data_size > handle->size) {
		smb_update_read_ptr(drvdata, sdb->data_size - handle->size);
		lost = true;
	}

	data_size = sdb->data_size;
	smb_sync_perf_buffer(drvdata, buf, handle->head);
	if (!buf->snapshot && lost)
		perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);

	return data_size;
}

static const struct coresight_ops_sink smb_cs_ops = {
	.enable		= smb_enable,
	.disable	= smb_disable,
	.alloc_buffer	= smb_alloc_buffer,
	.free_buffer	= smb_free_buffer,
	.update_buffer	= smb_update_buffer,
};

static const struct coresight_ops cs_ops = {
	.sink_ops	= &smb_cs_ops,
};

static int smb_init_data_buffer(struct platform_device *pdev,
				struct smb_data_buffer *sdb)
{
	struct resource *res;
	void *base;

	res = platform_get_resource(pdev, IORESOURCE_MEM, SMB_BUF_ADDR_RES);
	if (!res) {
		dev_err(&pdev->dev, "SMB device failed to get resource\n");
		return -EINVAL;
	}

	sdb->buf_rdptr = 0;
	sdb->buf_hw_base = FIELD_GET(SMB_BUF_ADDR_LO_MSK, res->start);
	sdb->buf_size = resource_size(res);
	if (sdb->buf_size == 0)
		return -EINVAL;

	/*
	 * This is a chunk of memory, use classic mapping with better
	 * performance.
	 */
	base = devm_memremap(&pdev->dev, sdb->buf_hw_base, sdb->buf_size,
				MEMREMAP_WB);
	if (IS_ERR(base))
		return PTR_ERR(base);

	sdb->buf_base = base;

	return 0;
}

static void smb_init_hw(struct smb_drv_data *drvdata)
{
	smb_disable_hw(drvdata);

	writel(SMB_LB_CFG_LO_DEFAULT, drvdata->base + SMB_LB_CFG_LO_REG);
	writel(SMB_LB_CFG_HI_DEFAULT, drvdata->base + SMB_LB_CFG_HI_REG);
	writel(SMB_GLB_CFG_DEFAULT, drvdata->base + SMB_GLB_CFG_REG);
	writel(SMB_GLB_INT_CFG, drvdata->base + SMB_GLB_INT_REG);
	writel(SMB_LB_INT_CTRL_CFG, drvdata->base + SMB_LB_INT_CTRL_REG);
}

static int smb_register_sink(struct platform_device *pdev,
			     struct smb_drv_data *drvdata)
{
	struct coresight_platform_data *pdata = NULL;
	struct coresight_desc desc = { 0 };
	int ret;

	pdata = coresight_get_platform_data(&pdev->dev);
	if (IS_ERR(pdata))
		return PTR_ERR(pdata);

	desc.type = CORESIGHT_DEV_TYPE_SINK;
	desc.subtype.sink_subtype = CORESIGHT_DEV_SUBTYPE_SINK_BUFFER;
	desc.ops = &cs_ops;
	desc.pdata = pdata;
	desc.dev = &pdev->dev;
	desc.groups = smb_sink_groups;
	desc.name = coresight_alloc_device_name(&sink_devs, &pdev->dev);
	if (!desc.name) {
		dev_err(&pdev->dev, "Failed to alloc coresight device name");
		return -ENOMEM;
	}
	desc.access = CSDEV_ACCESS_IOMEM(drvdata->base);

	drvdata->csdev = coresight_register(&desc);
	if (IS_ERR(drvdata->csdev))
		return PTR_ERR(drvdata->csdev);

	drvdata->miscdev.name = desc.name;
	drvdata->miscdev.minor = MISC_DYNAMIC_MINOR;
	drvdata->miscdev.fops = &smb_fops;
	ret = misc_register(&drvdata->miscdev);
	if (ret) {
		coresight_unregister(drvdata->csdev);
		dev_err(&pdev->dev, "Failed to register misc, ret=%d\n", ret);
	}

	return ret;
}

static void smb_unregister_sink(struct smb_drv_data *drvdata)
{
	misc_deregister(&drvdata->miscdev);
	coresight_unregister(drvdata->csdev);
}

static int smb_config_inport(struct device *dev, bool enable)
{
	u64 func = enable ? 1 : 0;
	union acpi_object *obj;
	guid_t guid;
	u64 rev = 0;

	/*
	 * Using DSM calls to enable/disable ultrasoc hardwares on
	 * tracing path, to prevent ultrasoc packet format being exposed.
	 */
	if (guid_parse(ULTRASOC_SMB_DSM_UUID, &guid)) {
		dev_err(dev, "Get GUID failed\n");
		return -EINVAL;
	}

	obj = acpi_evaluate_dsm(ACPI_HANDLE(dev), &guid, rev, func, NULL);
	if (!obj) {
		dev_err(dev, "ACPI handle failed\n");
		return -ENODEV;
	}

	ACPI_FREE(obj);

	return 0;
}

static int smb_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct smb_drv_data *drvdata;
	int ret;

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

	drvdata->base = devm_platform_ioremap_resource(pdev, SMB_REG_ADDR_RES);
	if (IS_ERR(drvdata->base)) {
		dev_err(dev, "Failed to ioremap resource\n");
		return PTR_ERR(drvdata->base);
	}

	smb_init_hw(drvdata);

	ret = smb_init_data_buffer(pdev, &drvdata->sdb);
	if (ret) {
		dev_err(dev, "Failed to init buffer, ret = %d\n", ret);
		return ret;
	}

	ret = smb_config_inport(dev, true);
	if (ret)
		return ret;

	smb_reset_buffer(drvdata);
	platform_set_drvdata(pdev, drvdata);
	spin_lock_init(&drvdata->spinlock);
	drvdata->pid = -1;

	ret = smb_register_sink(pdev, drvdata);
	if (ret) {
		smb_config_inport(&pdev->dev, false);
		dev_err(dev, "Failed to register SMB sink\n");
		return ret;
	}

	return 0;
}

static void smb_remove(struct platform_device *pdev)
{
	struct smb_drv_data *drvdata = platform_get_drvdata(pdev);

	smb_unregister_sink(drvdata);

	smb_config_inport(&pdev->dev, false);
}

#ifdef CONFIG_ACPI
static const struct acpi_device_id ultrasoc_smb_acpi_match[] = {
	{"HISI03A1", 0, 0, 0},
	{}
};
MODULE_DEVICE_TABLE(acpi, ultrasoc_smb_acpi_match);
#endif

static struct platform_driver smb_driver = {
	.driver = {
		.name = "ultrasoc-smb",
		.acpi_match_table = ACPI_PTR(ultrasoc_smb_acpi_match),
		.suppress_bind_attrs = true,
	},
	.probe = smb_probe,
	.remove_new = smb_remove,
};
module_platform_driver(smb_driver);

MODULE_DESCRIPTION("UltraSoc SMB CoreSight driver");
MODULE_LICENSE("Dual MIT/GPL");
MODULE_AUTHOR("Jonathan Zhou <jonathan.zhouwen@huawei.com>");
MODULE_AUTHOR("Qi Liu <liuqi115@huawei.com>");