// SPDX-License-Identifier: GPL-2.0-only OR MIT
/* Copyright 2021 Alyssa Rosenzweig <alyssa@rosenzweig.io> */

#include <linux/align.h>
#include <linux/bitfield.h>
#include <linux/bitmap.h>
#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/iommu.h>
#include <linux/kref.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/ratelimit.h>
#include <linux/slab.h>
#include <linux/soc/apple/rtkit.h>

#include <drm/drm_fb_dma_helper.h>
#include <drm/drm_fourcc.h>
#include <drm/drm_framebuffer.h>
#include <drm/drm_gem_dma_helper.h>
#include <drm/drm_probe_helper.h>
#include <drm/drm_vblank.h>

#include "dcp.h"
#include "dcp-internal.h"
#include "iomfb.h"
#include "iomfb_internal.h"
#include "parser.h"
#include "trace.h"

static int dcp_tx_offset(enum dcp_context_id id)
{
	switch (id) {
	case DCP_CONTEXT_CB:
	case DCP_CONTEXT_CMD:
		return 0x00000;
	case DCP_CONTEXT_OOBCB:
	case DCP_CONTEXT_OOBCMD:
		return 0x08000;
	default:
		return -EINVAL;
	}
}

static int dcp_channel_offset(enum dcp_context_id id)
{
	switch (id) {
	case DCP_CONTEXT_ASYNC:
		return 0x40000;
	case DCP_CONTEXT_OOBASYNC:
		return 0x48000;
	case DCP_CONTEXT_CB:
		return 0x60000;
	case DCP_CONTEXT_OOBCB:
		return 0x68000;
	default:
		return dcp_tx_offset(id);
	}
}

static inline u64 dcpep_set_shmem(u64 dart_va)
{
	return FIELD_PREP(IOMFB_MESSAGE_TYPE, IOMFB_MESSAGE_TYPE_SET_SHMEM) |
	       FIELD_PREP(IOMFB_SHMEM_FLAG, IOMFB_SHMEM_FLAG_VALUE) |
	       FIELD_PREP(IOMFB_SHMEM_DVA, dart_va);
}

static inline u64 dcpep_msg(enum dcp_context_id id, u32 length, u16 offset)
{
	return FIELD_PREP(IOMFB_MESSAGE_TYPE, IOMFB_MESSAGE_TYPE_MSG) |
		FIELD_PREP(IOMFB_MSG_CONTEXT, id) |
		FIELD_PREP(IOMFB_MSG_OFFSET, offset) |
		FIELD_PREP(IOMFB_MSG_LENGTH, length);
}

static inline u64 dcpep_ack(enum dcp_context_id id)
{
	return dcpep_msg(id, 0, 0) | IOMFB_MSG_ACK;
}

/*
 * A channel is busy if we have sent a message that has yet to be
 * acked. The driver must not sent a message to a busy channel.
 */
static bool dcp_channel_busy(struct dcp_channel *ch)
{
	return (ch->depth != 0);
}

/*
 * Get the context ID passed to the DCP for a command we push. The rule is
 * simple: callback contexts are used when replying to the DCP, command
 * contexts are used otherwise. That corresponds to a non/zero call stack
 * depth. This rule frees the caller from tracking the call context manually.
 */
static enum dcp_context_id dcp_call_context(struct apple_dcp *dcp, bool oob)
{
	u8 depth = oob ? dcp->ch_oobcmd.depth : dcp->ch_cmd.depth;

	if (depth)
		return oob ? DCP_CONTEXT_OOBCB : DCP_CONTEXT_CB;
	else
		return oob ? DCP_CONTEXT_OOBCMD : DCP_CONTEXT_CMD;
}

/* Get a channel for a context */
static struct dcp_channel *dcp_get_channel(struct apple_dcp *dcp,
					   enum dcp_context_id context)
{
	switch (context) {
	case DCP_CONTEXT_CB:
		return &dcp->ch_cb;
	case DCP_CONTEXT_CMD:
		return &dcp->ch_cmd;
	case DCP_CONTEXT_OOBCB:
		return &dcp->ch_oobcb;
	case DCP_CONTEXT_OOBCMD:
		return &dcp->ch_oobcmd;
	case DCP_CONTEXT_ASYNC:
		return &dcp->ch_async;
	case DCP_CONTEXT_OOBASYNC:
		return &dcp->ch_oobasync;
	default:
		return NULL;
	}
}

/* Get the start of a packet: after the end of the previous packet */
static u16 dcp_packet_start(struct dcp_channel *ch, u8 depth)
{
	if (depth > 0)
		return ch->end[depth - 1];
	else
		return 0;
}

/* Pushes and pops the depth of the call stack with safety checks */
static u8 dcp_push_depth(u8 *depth)
{
	u8 ret = (*depth)++;

	WARN_ON(ret >= DCP_MAX_CALL_DEPTH);
	return ret;
}

static u8 dcp_pop_depth(u8 *depth)
{
	WARN_ON((*depth) == 0);

	return --(*depth);
}

/* Call a DCP function given by a tag */
void dcp_push(struct apple_dcp *dcp, bool oob, const struct dcp_method_entry *call,
		     u32 in_len, u32 out_len, void *data, dcp_callback_t cb,
		     void *cookie)
{
	enum dcp_context_id context = dcp_call_context(dcp, oob);
	struct dcp_channel *ch = dcp_get_channel(dcp, context);

	struct dcp_packet_header header = {
		.in_len = in_len,
		.out_len = out_len,

		/* Tag is reversed due to endianness of the fourcc */
		.tag[0] = call->tag[3],
		.tag[1] = call->tag[2],
		.tag[2] = call->tag[1],
		.tag[3] = call->tag[0],
	};

	u8 depth = dcp_push_depth(&ch->depth);
	u16 offset = dcp_packet_start(ch, depth);

	void *out = dcp->shmem + dcp_tx_offset(context) + offset;
	void *out_data = out + sizeof(header);
	size_t data_len = sizeof(header) + in_len + out_len;

	memcpy(out, &header, sizeof(header));

	if (in_len > 0)
		memcpy(out_data, data, in_len);

	trace_iomfb_push(dcp, call, context, offset, depth);

	ch->callbacks[depth] = cb;
	ch->cookies[depth] = cookie;
	ch->output[depth] = out + sizeof(header) + in_len;
	ch->end[depth] = offset + ALIGN(data_len, DCP_PACKET_ALIGNMENT);

	dcp_send_message(dcp, IOMFB_ENDPOINT,
			 dcpep_msg(context, data_len, offset));
}

/* Parse a callback tag "D123" into the ID 123. Returns -EINVAL on failure. */
int dcp_parse_tag(char tag[4])
{
	u32 d[3];
	int i;

	if (tag[3] != 'D')
		return -EINVAL;

	for (i = 0; i < 3; ++i) {
		d[i] = (u32)(tag[i] - '0');

		if (d[i] > 9)
			return -EINVAL;
	}

	return d[0] + (d[1] * 10) + (d[2] * 100);
}

/* Ack a callback from the DCP */
void dcp_ack(struct apple_dcp *dcp, enum dcp_context_id context)
{
	struct dcp_channel *ch = dcp_get_channel(dcp, context);

	dcp_pop_depth(&ch->depth);
	dcp_send_message(dcp, IOMFB_ENDPOINT,
			 dcpep_ack(context));
}

/*
 * Helper to send a DRM hotplug event. The DCP is accessed from a single
 * (RTKit) thread. To handle hotplug callbacks, we need to call
 * drm_kms_helper_hotplug_event, which does an atomic commit (via DCP) and
 * waits for vblank (a DCP callback). That means we deadlock if we call from
 * the RTKit thread! Instead, move the call to another thread via a workqueue.
 */
void dcp_hotplug(struct work_struct *work)
{
	struct apple_connector *connector;
	struct apple_dcp *dcp;

	connector = container_of(work, struct apple_connector, hotplug_wq);

	dcp = platform_get_drvdata(connector->dcp);
	dev_info(dcp->dev, "%s() connected:%d valid_mode:%d nr_modes:%u\n", __func__,
		 connector->connected, dcp->valid_mode, dcp->nr_modes);

	/*
	 * DCP defers link training until we set a display mode. But we set
	 * display modes from atomic_flush, so userspace needs to trigger a
	 * flush, or the CRTC gets no signal.
	 */
	if (connector->base.state && !dcp->valid_mode && connector->connected)
		drm_connector_set_link_status_property(&connector->base,
						       DRM_MODE_LINK_STATUS_BAD);

	drm_kms_helper_connector_hotplug_event(&connector->base);
}
EXPORT_SYMBOL_GPL(dcp_hotplug);

static void dcpep_handle_cb(struct apple_dcp *dcp, enum dcp_context_id context,
			    void *data, u32 length, u16 offset)
{
	struct device *dev = dcp->dev;
	struct dcp_packet_header *hdr = data;
	void *in, *out;
	int tag = dcp_parse_tag(hdr->tag);
	struct dcp_channel *ch = dcp_get_channel(dcp, context);
	u8 depth;

	if (tag < 0 || tag >= IOMFB_MAX_CB || !dcp->cb_handlers || !dcp->cb_handlers[tag]) {
		dev_warn(dev, "received unknown callback %c%c%c%c\n",
			 hdr->tag[3], hdr->tag[2], hdr->tag[1], hdr->tag[0]);
		return;
	}

	in = data + sizeof(*hdr);
	out = in + hdr->in_len;

	// TODO: verify that in_len and out_len match our prototypes
	// for now just clear the out data to have at least consistent results
	if (hdr->out_len)
		memset(out, 0, hdr->out_len);

	depth = dcp_push_depth(&ch->depth);
	ch->output[depth] = out;
	ch->end[depth] = offset + ALIGN(length, DCP_PACKET_ALIGNMENT);

	if (dcp->cb_handlers[tag](dcp, tag, out, in))
		dcp_ack(dcp, context);
}

static void dcpep_handle_ack(struct apple_dcp *dcp, enum dcp_context_id context,
			     void *data, u32 length)
{
	struct dcp_packet_header *header = data;
	struct dcp_channel *ch = dcp_get_channel(dcp, context);
	void *cookie;
	dcp_callback_t cb;

	if (!ch) {
		dev_warn(dcp->dev, "ignoring ack on context %X\n", context);
		return;
	}

	dcp_pop_depth(&ch->depth);

	cb = ch->callbacks[ch->depth];
	cookie = ch->cookies[ch->depth];

	ch->callbacks[ch->depth] = NULL;
	ch->cookies[ch->depth] = NULL;

	if (cb)
		cb(dcp, data + sizeof(*header) + header->in_len, cookie);
}

static void dcpep_got_msg(struct apple_dcp *dcp, u64 message)
{
	enum dcp_context_id ctx_id;
	u16 offset;
	u32 length;
	int channel_offset;
	void *data;

	ctx_id = FIELD_GET(IOMFB_MSG_CONTEXT, message);
	offset = FIELD_GET(IOMFB_MSG_OFFSET, message);
	length = FIELD_GET(IOMFB_MSG_LENGTH, message);

	channel_offset = dcp_channel_offset(ctx_id);

	if (channel_offset < 0) {
		dev_warn(dcp->dev, "invalid context received %u\n", ctx_id);
		return;
	}

	data = dcp->shmem + channel_offset + offset;

	if (FIELD_GET(IOMFB_MSG_ACK, message))
		dcpep_handle_ack(dcp, ctx_id, data, length);
	else
		dcpep_handle_cb(dcp, ctx_id, data, length, offset);
}

/*
 * DRM specifies rectangles as start and end coordinates.  DCP specifies
 * rectangles as a start coordinate and a width/height. Convert a DRM rectangle
 * to a DCP rectangle.
 */
struct dcp_rect drm_to_dcp_rect(struct drm_rect *rect)
{
	return (struct dcp_rect){ .x = rect->x1,
				  .y = rect->y1,
				  .w = drm_rect_width(rect),
				  .h = drm_rect_height(rect) };
}

u32 drm_format_to_dcp(u32 drm)
{
	switch (drm) {
	case DRM_FORMAT_XRGB8888:
	case DRM_FORMAT_ARGB8888:
		return fourcc_code('A', 'R', 'G', 'B');

	case DRM_FORMAT_XBGR8888:
	case DRM_FORMAT_ABGR8888:
		return fourcc_code('A', 'B', 'G', 'R');

	case DRM_FORMAT_XRGB2101010:
		return fourcc_code('r', '0', '3', 'w');
	}

	pr_warn("DRM format %X not supported in DCP\n", drm);
	return 0;
}

int dcp_get_modes(struct drm_connector *connector)
{
	struct apple_connector *apple_connector = to_apple_connector(connector);
	struct platform_device *pdev = apple_connector->dcp;
	struct apple_dcp *dcp = platform_get_drvdata(pdev);

	struct drm_device *dev = connector->dev;
	struct drm_display_mode *mode;
	int i;

	for (i = 0; i < dcp->nr_modes; ++i) {
		mode = drm_mode_duplicate(dev, &dcp->modes[i].mode);

		if (!mode) {
			dev_err(dev->dev, "Failed to duplicate display mode\n");
			return 0;
		}

		drm_mode_probed_add(connector, mode);
	}

	return dcp->nr_modes;
}
EXPORT_SYMBOL_GPL(dcp_get_modes);

/* The user may own drm_display_mode, so we need to search for our copy */
struct dcp_display_mode *lookup_mode(struct apple_dcp *dcp,
					    const struct drm_display_mode *mode)
{
	int i;

	for (i = 0; i < dcp->nr_modes; ++i) {
		if (drm_mode_match(mode, &dcp->modes[i].mode,
				   DRM_MODE_MATCH_TIMINGS |
					   DRM_MODE_MATCH_CLOCK))
			return &dcp->modes[i];
	}

	return NULL;
}

int dcp_mode_valid(struct drm_connector *connector,
		   struct drm_display_mode *mode)
{
	struct apple_connector *apple_connector = to_apple_connector(connector);
	struct platform_device *pdev = apple_connector->dcp;
	struct apple_dcp *dcp = platform_get_drvdata(pdev);

	return lookup_mode(dcp, mode) ? MODE_OK : MODE_BAD;
}
EXPORT_SYMBOL_GPL(dcp_mode_valid);

int dcp_crtc_atomic_modeset(struct drm_crtc *crtc,
			    struct drm_atomic_state *state)
{
	struct apple_crtc *apple_crtc = to_apple_crtc(crtc);
	struct apple_dcp *dcp = platform_get_drvdata(apple_crtc->dcp);
	struct drm_crtc_state *crtc_state;
	int ret = -EIO;
	bool modeset;

	crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
	if (!crtc_state)
		return 0;

	modeset = drm_atomic_crtc_needs_modeset(crtc_state) || !dcp->valid_mode;

	if (!modeset)
		return 0;

	/* ignore no mode, poweroff is handled elsewhere */
	if (crtc_state->mode.hdisplay == 0 && crtc_state->mode.vdisplay == 0)
		return 0;

	switch (dcp->fw_compat) {
	case DCP_FIRMWARE_V_12_3:
		ret = iomfb_modeset_v12_3(dcp, crtc_state);
		break;
	case DCP_FIRMWARE_V_13_5:
		ret = iomfb_modeset_v13_3(dcp, crtc_state);
		break;
	default:
		WARN_ONCE(true, "Unexpected firmware version: %u\n",
			  dcp->fw_compat);
		break;
	}

	return ret;
}
EXPORT_SYMBOL_GPL(dcp_crtc_atomic_modeset);

bool dcp_crtc_mode_fixup(struct drm_crtc *crtc,
			 const struct drm_display_mode *mode,
			 struct drm_display_mode *adjusted_mode)
{
	struct apple_crtc *apple_crtc = to_apple_crtc(crtc);
	struct platform_device *pdev = apple_crtc->dcp;
	struct apple_dcp *dcp = platform_get_drvdata(pdev);

	/* TODO: support synthesized modes through scaling */
	return lookup_mode(dcp, mode) != NULL;
}
EXPORT_SYMBOL(dcp_crtc_mode_fixup);


void dcp_flush(struct drm_crtc *crtc, struct drm_atomic_state *state)
{
	struct platform_device *pdev = to_apple_crtc(crtc)->dcp;
	struct apple_dcp *dcp = platform_get_drvdata(pdev);

	if (dcp_channel_busy(&dcp->ch_cmd))
	{
		dev_err(dcp->dev, "unexpected busy command channel\n");
		/* HACK: issue a delayed vblank event to avoid timeouts in
		 * drm_atomic_helper_wait_for_vblanks().
		 */
		schedule_work(&dcp->vblank_wq);
		return;
	}

	switch (dcp->fw_compat) {
	case DCP_FIRMWARE_V_12_3:
		iomfb_flush_v12_3(dcp, crtc, state);
		break;
	case DCP_FIRMWARE_V_13_5:
		iomfb_flush_v13_3(dcp, crtc, state);
		break;
	default:
		WARN_ONCE(true, "Unexpected firmware version: %u\n", dcp->fw_compat);
		break;
	}
}
EXPORT_SYMBOL_GPL(dcp_flush);

static void iomfb_start(struct apple_dcp *dcp)
{
	switch (dcp->fw_compat) {
	case DCP_FIRMWARE_V_12_3:
		iomfb_start_v12_3(dcp);
		break;
	case DCP_FIRMWARE_V_13_5:
		iomfb_start_v13_3(dcp);
		break;
	default:
		WARN_ONCE(true, "Unexpected firmware version: %u\n", dcp->fw_compat);
		break;
	}
}

bool dcp_is_initialized(struct platform_device *pdev)
{
	struct apple_dcp *dcp = platform_get_drvdata(pdev);

	return dcp->active;
}
EXPORT_SYMBOL_GPL(dcp_is_initialized);

void iomfb_recv_msg(struct apple_dcp *dcp, u64 message)
{
	enum dcpep_type type = FIELD_GET(IOMFB_MESSAGE_TYPE, message);

	if (type == IOMFB_MESSAGE_TYPE_INITIALIZED)
		iomfb_start(dcp);
	else if (type == IOMFB_MESSAGE_TYPE_MSG)
		dcpep_got_msg(dcp, message);
	else
		dev_warn(dcp->dev, "Ignoring unknown message %llx\n", message);
}

int iomfb_start_rtkit(struct apple_dcp *dcp)
{
	dma_addr_t shmem_iova;
	apple_rtkit_start_ep(dcp->rtk, IOMFB_ENDPOINT);

	dcp->shmem = dma_alloc_coherent(dcp->dev, DCP_SHMEM_SIZE, &shmem_iova,
					GFP_KERNEL);

	dcp_send_message(dcp, IOMFB_ENDPOINT, dcpep_set_shmem(shmem_iova));

	return 0;
}

void iomfb_shutdown(struct apple_dcp *dcp)
{
	/* We're going down */
	dcp->active = false;
	dcp->valid_mode = false;

	switch (dcp->fw_compat) {
	case DCP_FIRMWARE_V_12_3:
		iomfb_shutdown_v12_3(dcp);
		break;
	case DCP_FIRMWARE_V_13_5:
		iomfb_shutdown_v13_3(dcp);
		break;
	default:
		WARN_ONCE(true, "Unexpected firmware version: %u\n", dcp->fw_compat);
		break;
	}
}