linux/drivers/gpu/drm/tidss/tidss_oldi.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2025 - Texas Instruments Incorporated
 *
 * Aradhya Bhatia <a-bhatia1@ti.com>
 */

#include <linux/clk.h>
#include <linux/of.h>
#include <linux/of_graph.h>
#include <linux/mfd/syscon.h>
#include <linux/media-bus-format.h>
#include <linux/regmap.h>

#include <drm/drm_atomic_helper.h>
#include <drm/drm_bridge.h>
#include <drm/drm_of.h>

#include "tidss_dispc.h"
#include "tidss_dispc_regs.h"
#include "tidss_oldi.h"

struct tidss_oldi {
	struct tidss_device	*tidss;
	struct device		*dev;

	struct drm_bridge	bridge;
	struct drm_bridge	*next_bridge;

	enum tidss_oldi_link_type link_type;
	const struct oldi_bus_format *bus_format;
	u32 oldi_instance;
	int companion_instance;	/* -1 when OLDI TX operates in Single-Link */
	u32 parent_vp;

	struct clk *serial;
	struct regmap *io_ctrl;
};

struct oldi_bus_format {
	u32 bus_fmt;
	u32 data_width;
	enum oldi_mode_reg_val oldi_mode_reg_val;
	u32 input_bus_fmt;
};

static const struct oldi_bus_format oldi_bus_formats[] = {
	{ MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,	18, SPWG_18,	MEDIA_BUS_FMT_RGB666_1X18 },
	{ MEDIA_BUS_FMT_RGB888_1X7X4_SPWG,	24, SPWG_24,	MEDIA_BUS_FMT_RGB888_1X24 },
	{ MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA,	24, JEIDA_24,	MEDIA_BUS_FMT_RGB888_1X24 },
};

#define OLDI_IDLE_CLK_HZ	25000000 /*25 MHz */

static inline struct tidss_oldi *
drm_bridge_to_tidss_oldi(struct drm_bridge *bridge)
{
	return container_of(bridge, struct tidss_oldi, bridge);
}

static int tidss_oldi_bridge_attach(struct drm_bridge *bridge,
				    struct drm_encoder *encoder,
				    enum drm_bridge_attach_flags flags)
{
	struct tidss_oldi *oldi = drm_bridge_to_tidss_oldi(bridge);

	if (!oldi->next_bridge) {
		dev_err(oldi->dev,
			"%s: OLDI%u Failure attach next bridge\n",
			__func__, oldi->oldi_instance);
		return -ENODEV;
	}

	if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)) {
		dev_err(oldi->dev,
			"%s: OLDI%u DRM_BRIDGE_ATTACH_NO_CONNECTOR is mandatory.\n",
			__func__, oldi->oldi_instance);
		return -EINVAL;
	}

	return drm_bridge_attach(encoder, oldi->next_bridge, bridge, flags);
}

static int
tidss_oldi_set_serial_clk(struct tidss_oldi *oldi, unsigned long rate)
{
	unsigned long new_rate;
	int ret;

	ret = clk_set_rate(oldi->serial, rate);
	if (ret) {
		dev_err(oldi->dev,
			"OLDI%u: failed to set serial clk rate to %lu Hz\n",
			 oldi->oldi_instance, rate);
		return ret;
	}

	new_rate = clk_get_rate(oldi->serial);

	if (dispc_pclk_diff(rate, new_rate) > 5)
		dev_warn(oldi->dev,
			 "OLDI%u Clock rate %lu differs over 5%% from requested %lu\n",
			 oldi->oldi_instance, new_rate, rate);

	dev_dbg(oldi->dev, "OLDI%u: new rate %lu Hz (requested %lu Hz)\n",
		oldi->oldi_instance, clk_get_rate(oldi->serial), rate);

	return 0;
}

static void tidss_oldi_tx_power(struct tidss_oldi *oldi, bool enable)
{
	u32 mask;

	/*
	 * The power control bits are Active Low, and remain powered off by
	 * default. That is, the bits are set to 1. To power on the OLDI TXes,
	 * the bits must be cleared to 0. Since there are cases where not all
	 * OLDI TXes are being used, the power logic selectively powers them
	 * on.
	 * Setting the variable 'val' to particular bit masks, makes sure that
	 * the undesired OLDI TXes remain powered off.
	 */

	if (enable) {
		switch (oldi->link_type) {
		case OLDI_MODE_SINGLE_LINK:
			/* Power-on only the required OLDI TX's IO*/
			mask = OLDI_PWRDOWN_TX(oldi->oldi_instance) | OLDI_PWRDN_BG;
			break;
		case OLDI_MODE_CLONE_SINGLE_LINK:
		case OLDI_MODE_DUAL_LINK:
			/* Power-on both the OLDI TXes' IOs */
			mask = OLDI_PWRDOWN_TX(oldi->oldi_instance) |
			       OLDI_PWRDOWN_TX(oldi->companion_instance) |
			       OLDI_PWRDN_BG;
			break;
		default:
			/*
			 * This code execution should never reach here as any
			 * OLDI with an unsupported OLDI mode would never get
			 * registered in the first place.
			 * However, power-off the OLDI in concern just in case.
			 */
			mask = OLDI_PWRDOWN_TX(oldi->oldi_instance);
			enable = false;
			break;
		}
	} else {
		switch (oldi->link_type) {
		case OLDI_MODE_CLONE_SINGLE_LINK:
		case OLDI_MODE_DUAL_LINK:
			mask = OLDI_PWRDOWN_TX(oldi->oldi_instance) |
			       OLDI_PWRDOWN_TX(oldi->companion_instance) |
			       OLDI_PWRDN_BG;
			break;
		case OLDI_MODE_SINGLE_LINK:
		default:
			mask = OLDI_PWRDOWN_TX(oldi->oldi_instance);
			break;
		}
	}

	regmap_update_bits(oldi->io_ctrl, OLDI_PD_CTRL, mask, enable ? 0 : mask);
}

static int tidss_oldi_config(struct tidss_oldi *oldi)
{
	const struct oldi_bus_format *bus_fmt = NULL;
	u32 oldi_cfg = 0;
	int ret;

	bus_fmt = oldi->bus_format;

	/*
	 * MASTERSLAVE and SRC bits of OLDI Config are always set to 0.
	 */

	if (bus_fmt->data_width == 24)
		oldi_cfg |= OLDI_MSB;
	else if (bus_fmt->data_width != 18)
		dev_warn(oldi->dev,
			 "OLDI%u: DSS port width %d not supported\n",
			 oldi->oldi_instance, bus_fmt->data_width);

	oldi_cfg |= OLDI_DEPOL;

	oldi_cfg = (oldi_cfg & (~OLDI_MAP)) | (bus_fmt->oldi_mode_reg_val << 1);

	oldi_cfg |= OLDI_SOFTRST;

	oldi_cfg |= OLDI_ENABLE;

	switch (oldi->link_type) {
	case OLDI_MODE_SINGLE_LINK:
		/* All configuration is done for this mode.  */
		break;

	case OLDI_MODE_CLONE_SINGLE_LINK:
		oldi_cfg |= OLDI_CLONE_MODE;
		break;

	case OLDI_MODE_DUAL_LINK:
		/* data-mapping field also indicates dual-link mode */
		oldi_cfg |= BIT(3);
		oldi_cfg |= OLDI_DUALMODESYNC;
		break;

	default:
		dev_err(oldi->dev, "OLDI%u: Unsupported mode.\n",
			oldi->oldi_instance);
		return -EINVAL;
	}

	ret = tidss_configure_oldi(oldi->tidss, oldi->parent_vp, oldi_cfg);
	if (ret == -ETIMEDOUT)
		dev_warn(oldi->dev, "OLDI%u: timeout waiting for OLDI reset done.\n",
			 oldi->oldi_instance);

	return ret;
}

static void tidss_oldi_atomic_pre_enable(struct drm_bridge *bridge,
					 struct drm_atomic_state *state)
{
	struct tidss_oldi *oldi = drm_bridge_to_tidss_oldi(bridge);
	struct drm_connector *connector;
	struct drm_connector_state *conn_state;
	struct drm_crtc_state *crtc_state;
	struct drm_display_mode *mode;

	if (oldi->link_type == OLDI_MODE_SECONDARY_CLONE_SINGLE_LINK)
		return;

	connector = drm_atomic_get_new_connector_for_encoder(state,
							     bridge->encoder);
	if (WARN_ON(!connector))
		return;

	conn_state = drm_atomic_get_new_connector_state(state, connector);
	if (WARN_ON(!conn_state))
		return;

	crtc_state = drm_atomic_get_new_crtc_state(state, conn_state->crtc);
	if (WARN_ON(!crtc_state))
		return;

	mode = &crtc_state->adjusted_mode;

	/* Configure the OLDI params*/
	tidss_oldi_config(oldi);

	/* Set the OLDI serial clock (7 times the pixel clock) */
	tidss_oldi_set_serial_clk(oldi, mode->clock * 7 * 1000);

	/* Enable OLDI IO power */
	tidss_oldi_tx_power(oldi, true);
}

static void tidss_oldi_atomic_post_disable(struct drm_bridge *bridge,
					   struct drm_atomic_state *state)
{
	struct tidss_oldi *oldi = drm_bridge_to_tidss_oldi(bridge);

	if (oldi->link_type == OLDI_MODE_SECONDARY_CLONE_SINGLE_LINK)
		return;

	/* Disable OLDI IO power */
	tidss_oldi_tx_power(oldi, false);

	/* Set the OLDI serial clock to IDLE Frequency */
	tidss_oldi_set_serial_clk(oldi, OLDI_IDLE_CLK_HZ);

	/* Clear OLDI Config */
	tidss_disable_oldi(oldi->tidss, oldi->parent_vp);
}

#define MAX_INPUT_SEL_FORMATS	1

static u32 *tidss_oldi_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
						 struct drm_bridge_state *bridge_state,
						 struct drm_crtc_state *crtc_state,
						 struct drm_connector_state *conn_state,
						 u32 output_fmt,
						 unsigned int *num_input_fmts)
{
	struct tidss_oldi *oldi = drm_bridge_to_tidss_oldi(bridge);
	u32 *input_fmts;
	int i;

	*num_input_fmts = 0;

	for (i = 0; i < ARRAY_SIZE(oldi_bus_formats); i++)
		if (oldi_bus_formats[i].bus_fmt == output_fmt)
			break;

	if (i == ARRAY_SIZE(oldi_bus_formats))
		return NULL;

	input_fmts = kcalloc(MAX_INPUT_SEL_FORMATS, sizeof(*input_fmts),
			     GFP_KERNEL);
	if (!input_fmts)
		return NULL;

	*num_input_fmts = 1;
	input_fmts[0] = oldi_bus_formats[i].input_bus_fmt;
	oldi->bus_format = &oldi_bus_formats[i];

	return input_fmts;
}

static const struct drm_bridge_funcs tidss_oldi_bridge_funcs = {
	.attach	= tidss_oldi_bridge_attach,
	.atomic_pre_enable = tidss_oldi_atomic_pre_enable,
	.atomic_post_disable = tidss_oldi_atomic_post_disable,
	.atomic_get_input_bus_fmts = tidss_oldi_atomic_get_input_bus_fmts,
	.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
	.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
	.atomic_reset = drm_atomic_helper_bridge_reset,
};

static int get_oldi_mode(struct device_node *oldi_tx, int *companion_instance)
{
	struct device_node *companion;
	struct device_node *port0, *port1;
	u32 companion_reg;
	bool secondary_oldi = false;
	int pixel_order;

	/*
	 * Find if the OLDI is paired with another OLDI for combined OLDI
	 * operation (dual-link or clone).
	 */
	companion = of_parse_phandle(oldi_tx, "ti,companion-oldi", 0);
	if (!companion)
		/*
		 * The OLDI TX does not have a companion, nor is it a
		 * secondary OLDI. It will operate independently.
		 */
		return OLDI_MODE_SINGLE_LINK;

	if (of_property_read_u32(companion, "reg", &companion_reg))
		return OLDI_MODE_UNSUPPORTED;

	if (companion_reg > (TIDSS_MAX_OLDI_TXES - 1))
		/* Invalid companion OLDI reg value. */
		return OLDI_MODE_UNSUPPORTED;

	*companion_instance = (int)companion_reg;

	if (of_property_read_bool(oldi_tx, "ti,secondary-oldi"))
		secondary_oldi = true;

	/*
	 * We need to work out if the sink is expecting us to function in
	 * dual-link mode. We do this by looking at the DT port nodes, the
	 * OLDI TX ports are connected to. If they are marked as expecting
	 * even pixels and odd pixels, then we need to enable dual-link.
	 */
	port0 = of_graph_get_port_by_id(oldi_tx, 1);
	port1 = of_graph_get_port_by_id(companion, 1);
	pixel_order = drm_of_lvds_get_dual_link_pixel_order(port0, port1);
	of_node_put(port0);
	of_node_put(port1);
	of_node_put(companion);

	switch (pixel_order) {
	case -EINVAL:
		/*
		 * The dual-link properties were not found in at least
		 * one of the sink nodes. Since 2 OLDI ports are present
		 * in the DT, it can be safely assumed that the required
		 * configuration is Clone Mode.
		 */
		return (secondary_oldi ? OLDI_MODE_SECONDARY_CLONE_SINGLE_LINK :
					 OLDI_MODE_CLONE_SINGLE_LINK);

	case DRM_LVDS_DUAL_LINK_ODD_EVEN_PIXELS:
		/*
		 * Primary OLDI can only support "ODD" pixels. So, from its
		 * perspective, the pixel order has to be ODD-EVEN.
		 */
		return (secondary_oldi ? OLDI_MODE_UNSUPPORTED :
					 OLDI_MODE_DUAL_LINK);

	case DRM_LVDS_DUAL_LINK_EVEN_ODD_PIXELS:
		/*
		 * Secondary OLDI can only support "EVEN" pixels. So, from its
		 * perspective, the pixel order has to be EVEN-ODD.
		 */
		return (secondary_oldi ? OLDI_MODE_SECONDARY_DUAL_LINK :
					 OLDI_MODE_UNSUPPORTED);

	default:
		return OLDI_MODE_UNSUPPORTED;
	}
}

static int get_parent_dss_vp(struct device_node *oldi_tx, u32 *parent_vp)
{
	struct device_node *ep, *dss_port;
	int ret;

	ep = of_graph_get_endpoint_by_regs(oldi_tx, OLDI_INPUT_PORT, -1);
	if (ep) {
		dss_port = of_graph_get_remote_port(ep);
		if (!dss_port) {
			ret = -ENODEV;
			goto err_return_ep_port;
		}

		ret = of_property_read_u32(dss_port, "reg", parent_vp);

		of_node_put(dss_port);
err_return_ep_port:
		of_node_put(ep);
		return ret;
	}

	return -ENODEV;
}

static const struct drm_bridge_timings default_tidss_oldi_timings = {
	.input_bus_flags = DRM_BUS_FLAG_SYNC_SAMPLE_NEGEDGE
			 | DRM_BUS_FLAG_DE_HIGH,
};

void tidss_oldi_deinit(struct tidss_device *tidss)
{
	for (int i = 0; i < tidss->num_oldis; i++) {
		if (tidss->oldis[i]) {
			drm_bridge_remove(&tidss->oldis[i]->bridge);
			tidss->oldis[i] = NULL;
		}
	}
}

int tidss_oldi_init(struct tidss_device *tidss)
{
	struct tidss_oldi *oldi;
	struct device_node *child;
	struct drm_bridge *bridge;
	u32 parent_vp, oldi_instance;
	int companion_instance = -1;
	enum tidss_oldi_link_type link_type = OLDI_MODE_UNSUPPORTED;
	struct device_node *oldi_parent;
	int ret = 0;

	tidss->num_oldis = 0;

	oldi_parent = of_get_child_by_name(tidss->dev->of_node, "oldi-transmitters");
	if (!oldi_parent)
		/* Return gracefully */
		return 0;

	for_each_available_child_of_node(oldi_parent, child) {
		ret = get_parent_dss_vp(child, &parent_vp);
		if (ret) {
			if (ret == -ENODEV) {
				/*
				 * ENODEV means that this particular OLDI node
				 * is not connected with the DSS, which is not
				 * a harmful case. There could be another OLDI
				 * which may still be connected.
				 * Continue to search for that.
				 */
				continue;
			}
			goto err_put_node;
		}

		ret = of_property_read_u32(child, "reg", &oldi_instance);
		if (ret)
			goto err_put_node;

		/*
		 * Now that it's confirmed that OLDI is connected with DSS,
		 * let's continue getting the OLDI sinks ahead and other OLDI
		 * properties.
		 */
		bridge = devm_drm_of_get_bridge(tidss->dev, child,
						OLDI_OUTPUT_PORT, 0);
		if (IS_ERR(bridge)) {
			/*
			 * Either there was no OLDI sink in the devicetree, or
			 * the OLDI sink has not been added yet. In any case,
			 * return.
			 * We don't want to have an OLDI node connected to DSS
			 * but not to any sink.
			 */
			ret = dev_err_probe(tidss->dev, PTR_ERR(bridge),
					    "no panel/bridge for OLDI%u.\n",
					    oldi_instance);
			goto err_put_node;
		}

		link_type = get_oldi_mode(child, &companion_instance);
		if (link_type == OLDI_MODE_UNSUPPORTED) {
			ret = dev_err_probe(tidss->dev, -EINVAL,
					    "OLDI%u: Unsupported OLDI connection.\n",
					    oldi_instance);
			goto err_put_node;
		} else if ((link_type == OLDI_MODE_SECONDARY_CLONE_SINGLE_LINK) ||
			   (link_type == OLDI_MODE_CLONE_SINGLE_LINK)) {
			/*
			 * The OLDI driver cannot support OLDI clone mode
			 * properly at present.
			 * The clone mode requires 2 working encoder-bridge
			 * pipelines, generating from the same crtc. The DRM
			 * framework does not support this at present. If
			 * there were to be, say, 2 OLDI sink bridges each
			 * connected to an OLDI TXes, they couldn't both be
			 * supported simultaneously.
			 * This driver still has some code pertaining to OLDI
			 * clone mode configuration in DSS hardware for future,
			 * when there is a better infrastructure in the DRM
			 * framework to support 2 encoder-bridge pipelines
			 * simultaneously.
			 * Till that time, this driver shall error out if it
			 * detects a clone mode configuration.
			 */
			ret = dev_err_probe(tidss->dev, -EOPNOTSUPP,
					    "The OLDI driver does not support Clone Mode at present.\n");
			goto err_put_node;
		} else if (link_type == OLDI_MODE_SECONDARY_DUAL_LINK) {
			/*
			 * This is the secondary OLDI node, which serves as a
			 * companion to the primary OLDI, when it is configured
			 * for the dual-link mode. Since the primary OLDI will
			 * be a part of bridge chain, no need to put this one
			 * too. Continue onto the next OLDI node.
			 */
			continue;
		}

		oldi = devm_drm_bridge_alloc(tidss->dev, struct tidss_oldi, bridge,
					     &tidss_oldi_bridge_funcs);
		if (IS_ERR(oldi)) {
			ret = PTR_ERR(oldi);
			goto err_put_node;
		}

		oldi->parent_vp = parent_vp;
		oldi->oldi_instance = oldi_instance;
		oldi->companion_instance = companion_instance;
		oldi->link_type = link_type;
		oldi->dev = tidss->dev;
		oldi->next_bridge = bridge;

		/*
		 * Only the primary OLDI needs to reference the io-ctrl system
		 * registers, and the serial clock.
		 * We don't require a check for secondary OLDI in dual-link mode
		 * because the driver will not create a drm_bridge instance.
		 * But the driver will need to create a drm_bridge instance,
		 * for secondary OLDI in clone mode (once it is supported).
		 */
		if (link_type != OLDI_MODE_SECONDARY_CLONE_SINGLE_LINK) {
			oldi->io_ctrl = syscon_regmap_lookup_by_phandle(child,
									"ti,oldi-io-ctrl");
			if (IS_ERR(oldi->io_ctrl)) {
				ret = dev_err_probe(oldi->dev, PTR_ERR(oldi->io_ctrl),
						    "OLDI%u: syscon_regmap_lookup_by_phandle failed.\n",
						    oldi_instance);
				goto err_put_node;
			}

			oldi->serial = of_clk_get_by_name(child, "serial");
			if (IS_ERR(oldi->serial)) {
				ret = dev_err_probe(oldi->dev, PTR_ERR(oldi->serial),
						    "OLDI%u: Failed to get serial clock.\n",
						    oldi_instance);
				goto err_put_node;
			}
		}

		/* Register the bridge. */
		oldi->bridge.of_node = child;
		oldi->bridge.driver_private = oldi;
		oldi->bridge.timings = &default_tidss_oldi_timings;

		tidss->oldis[tidss->num_oldis++] = oldi;
		oldi->tidss = tidss;

		drm_bridge_add(&oldi->bridge);
	}

	of_node_put(child);
	of_node_put(oldi_parent);

	return 0;

err_put_node:
	of_node_put(child);
	of_node_put(oldi_parent);
	return ret;
}