Orange Pi5 kernel

// SPDX-License-Identifier: GPL-2.0
/*
 * DisplayPort CEC-Tunneling-over-AUX support
 *
 * Copyright 2018 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
 */
 
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
 
#include <media/cec.h>
 
#include <drm/drm_connector.h>
#include <drm/drm_device.h>
#include <drm/drm_dp_helper.h>
 
/*
 * Unfortunately it turns out that we have a chicken-and-egg situation
 * here. Quite a few active (mini-)DP-to-HDMI or USB-C-to-HDMI adapters
 * have a converter chip that supports CEC-Tunneling-over-AUX (usually the
 * Parade PS176), but they do not wire up the CEC pin, thus making CEC
 * useless. Note that MegaChips 2900-based adapters appear to have good
 * support for CEC tunneling. Those adapters that I have tested using
 * this chipset all have the CEC line connected.
 *
 * Sadly there is no way for this driver to know this. What happens is
 * that a /dev/cecX device is created that is isolated and unable to see
 * any of the other CEC devices. Quite literally the CEC wire is cut
 * (or in this case, never connected in the first place).
 *
 * The reason so few adapters support this is that this tunneling protocol
 * was never supported by any OS. So there was no easy way of testing it,
 * and no incentive to correctly wire up the CEC pin.
 *
 * Hopefully by creating this driver it will be easier for vendors to
 * finally fix their adapters and test the CEC functionality.
 *
 * I keep a list of known working adapters here:
 *
 * https://hverkuil.home.xs4all.nl/cec-status.txt
 *
 * Please mail me (hverkuil@xs4all.nl) if you find an adapter that works
 * and is not yet listed there.
 *
 * Note that the current implementation does not support CEC over an MST hub.
 * As far as I can see there is no mechanism defined in the DisplayPort
 * standard to transport CEC interrupts over an MST device. It might be
 * possible to do this through polling, but I have not been able to get that
 * to work.
 */
 
/**
 * DOC: dp cec helpers
 *
 * These functions take care of supporting the CEC-Tunneling-over-AUX
 * feature of DisplayPort-to-HDMI adapters.
 */
 
/*
 * When the EDID is unset because the HPD went low, then the CEC DPCD registers
 * typically can no longer be read (true for a DP-to-HDMI adapter since it is
 * powered by the HPD). However, some displays toggle the HPD off and on for a
 * short period for one reason or another, and that would cause the CEC adapter
 * to be removed and added again, even though nothing else changed.
 *
 * This module parameter sets a delay in seconds before the CEC adapter is
 * actually unregistered. Only if the HPD does not return within that time will
 * the CEC adapter be unregistered.
 *
 * If it is set to a value >= NEVER_UNREG_DELAY, then the CEC adapter will never
 * be unregistered for as long as the connector remains registered.
 *
 * If it is set to 0, then the CEC adapter will be unregistered immediately as
 * soon as the HPD disappears.
 *
 * The default is one second to prevent short HPD glitches from unregistering
 * the CEC adapter.
 *
 * Note that for integrated HDMI branch devices that support CEC the DPCD
 * registers remain available even if the HPD goes low since it is not powered
 * by the HPD. In that case the CEC adapter will never be unregistered during
 * the life time of the connector. At least, this is the theory since I do not
 * have hardware with an integrated HDMI branch device that supports CEC.
 */
#define NEVER_UNREG_DELAY 1000
static unsigned int drm_dp_cec_unregister_delay = 1;
module_param(drm_dp_cec_unregister_delay, uint, 0600);
MODULE_PARM_DESC(drm_dp_cec_unregister_delay,
<------><------> "CEC unregister delay in seconds, 0: no delay, >= 1000: never unregister");
 
static int drm_dp_cec_adap_enable(struct cec_adapter *adap, bool enable)
{
<------>struct drm_dp_aux *aux = cec_get_drvdata(adap);
<------>u32 val = enable ? DP_CEC_TUNNELING_ENABLE : 0;
<------>ssize_t err = 0;
 
<------>err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, val);
<------>return (enable && err < 0) ? err : 0;
}
 
static int drm_dp_cec_adap_log_addr(struct cec_adapter *adap, u8 addr)
{
<------>struct drm_dp_aux *aux = cec_get_drvdata(adap);
<------>/* Bit 15 (logical address 15) should always be set */
<------>u16 la_mask = 1 << CEC_LOG_ADDR_BROADCAST;
<------>u8 mask[2];
<------>ssize_t err;
 
<------>if (addr != CEC_LOG_ADDR_INVALID)
<------><------>la_mask |= adap->log_addrs.log_addr_mask | (1 << addr);
<------>mask[0] = la_mask & 0xff;
<------>mask[1] = la_mask >> 8;
<------>err = drm_dp_dpcd_write(aux, DP_CEC_LOGICAL_ADDRESS_MASK, mask, 2);
<------>return (addr != CEC_LOG_ADDR_INVALID && err < 0) ? err : 0;
}
 
static int drm_dp_cec_adap_transmit(struct cec_adapter *adap, u8 attempts,
<------><------><------><------>    u32 signal_free_time, struct cec_msg *msg)
{
<------>struct drm_dp_aux *aux = cec_get_drvdata(adap);
<------>unsigned int retries = min(5, attempts - 1);
<------>ssize_t err;
 
<------>err = drm_dp_dpcd_write(aux, DP_CEC_TX_MESSAGE_BUFFER,
<------><------><------><------>msg->msg, msg->len);
<------>if (err < 0)
<------><------>return err;
 
<------>err = drm_dp_dpcd_writeb(aux, DP_CEC_TX_MESSAGE_INFO,
<------><------><------><------> (msg->len - 1) | (retries << 4) |
<------><------><------><------> DP_CEC_TX_MESSAGE_SEND);
<------>return err < 0 ? err : 0;
}
 
static int drm_dp_cec_adap_monitor_all_enable(struct cec_adapter *adap,
<------><------><------><------><------>      bool enable)
{
<------>struct drm_dp_aux *aux = cec_get_drvdata(adap);
<------>ssize_t err;
<------>u8 val;
 
<------>if (!(adap->capabilities & CEC_CAP_MONITOR_ALL))
<------><------>return 0;
 
<------>err = drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_CONTROL, &val);
<------>if (err >= 0) {
<------><------>if (enable)
<------><------><------>val |= DP_CEC_SNOOPING_ENABLE;
<------><------>else
<------><------><------>val &= ~DP_CEC_SNOOPING_ENABLE;
<------><------>err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, val);
<------>}
<------>return (enable && err < 0) ? err : 0;
}
 
static void drm_dp_cec_adap_status(struct cec_adapter *adap,
<------><------><------><------>   struct seq_file *file)
{
<------>struct drm_dp_aux *aux = cec_get_drvdata(adap);
<------>struct drm_dp_desc desc;
<------>struct drm_dp_dpcd_ident *id = &desc.ident;
 
<------>if (drm_dp_read_desc(aux, &desc, true))
<------><------>return;
<------>seq_printf(file, "OUI: %*phD\n",
<------><------>   (int)sizeof(id->oui), id->oui);
<------>seq_printf(file, "ID: %*pE\n",
<------><------>   (int)strnlen(id->device_id, sizeof(id->device_id)),
<------><------>   id->device_id);
<------>seq_printf(file, "HW Rev: %d.%d\n", id->hw_rev >> 4, id->hw_rev & 0xf);
<------>/*
<------> * Show this both in decimal and hex: at least one vendor
<------> * always reports this in hex.
<------> */
<------>seq_printf(file, "FW/SW Rev: %d.%d (0x%02x.0x%02x)\n",
<------><------>   id->sw_major_rev, id->sw_minor_rev,
<------><------>   id->sw_major_rev, id->sw_minor_rev);
}
 
static const struct cec_adap_ops drm_dp_cec_adap_ops = {
<------>.adap_enable = drm_dp_cec_adap_enable,
<------>.adap_log_addr = drm_dp_cec_adap_log_addr,
<------>.adap_transmit = drm_dp_cec_adap_transmit,
<------>.adap_monitor_all_enable = drm_dp_cec_adap_monitor_all_enable,
<------>.adap_status = drm_dp_cec_adap_status,
};
 
static int drm_dp_cec_received(struct drm_dp_aux *aux)
{
<------>struct cec_adapter *adap = aux->cec.adap;
<------>struct cec_msg msg;
<------>u8 rx_msg_info;
<------>ssize_t err;
 
<------>err = drm_dp_dpcd_readb(aux, DP_CEC_RX_MESSAGE_INFO, &rx_msg_info);
<------>if (err < 0)
<------><------>return err;
 
<------>if (!(rx_msg_info & DP_CEC_RX_MESSAGE_ENDED))
<------><------>return 0;
 
<------>msg.len = (rx_msg_info & DP_CEC_RX_MESSAGE_LEN_MASK) + 1;
<------>err = drm_dp_dpcd_read(aux, DP_CEC_RX_MESSAGE_BUFFER, msg.msg, msg.len);
<------>if (err < 0)
<------><------>return err;
 
<------>cec_received_msg(adap, &msg);
<------>return 0;
}
 
static void drm_dp_cec_handle_irq(struct drm_dp_aux *aux)
{
<------>struct cec_adapter *adap = aux->cec.adap;
<------>u8 flags;
 
<------>if (drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, &flags) < 0)
<------><------>return;
 
<------>if (flags & DP_CEC_RX_MESSAGE_INFO_VALID)
<------><------>drm_dp_cec_received(aux);
 
<------>if (flags & DP_CEC_TX_MESSAGE_SENT)
<------><------>cec_transmit_attempt_done(adap, CEC_TX_STATUS_OK);
<------>else if (flags & DP_CEC_TX_LINE_ERROR)
<------><------>cec_transmit_attempt_done(adap, CEC_TX_STATUS_ERROR |
<------><------><------><------><------><------>CEC_TX_STATUS_MAX_RETRIES);
<------>else if (flags &
<------><------> (DP_CEC_TX_ADDRESS_NACK_ERROR | DP_CEC_TX_DATA_NACK_ERROR))
<------><------>cec_transmit_attempt_done(adap, CEC_TX_STATUS_NACK |
<------><------><------><------><------><------>CEC_TX_STATUS_MAX_RETRIES);
<------>drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, flags);
}
 
/**
 * drm_dp_cec_irq() - handle CEC interrupt, if any
 * @aux: DisplayPort AUX channel
 *
 * Should be called when handling an IRQ_HPD request. If CEC-tunneling-over-AUX
 * is present, then it will check for a CEC_IRQ and handle it accordingly.
 */
void drm_dp_cec_irq(struct drm_dp_aux *aux)
{
<------>u8 cec_irq;
<------>int ret;
 
<------>/* No transfer function was set, so not a DP connector */
<------>if (!aux->transfer)
<------><------>return;
 
<------>mutex_lock(&aux->cec.lock);
<------>if (!aux->cec.adap)
<------><------>goto unlock;
 
<------>ret = drm_dp_dpcd_readb(aux, DP_DEVICE_SERVICE_IRQ_VECTOR_ESI1,
<------><------><------><------>&cec_irq);
<------>if (ret < 0 || !(cec_irq & DP_CEC_IRQ))
<------><------>goto unlock;
 
<------>drm_dp_cec_handle_irq(aux);
<------>drm_dp_dpcd_writeb(aux, DP_DEVICE_SERVICE_IRQ_VECTOR_ESI1, DP_CEC_IRQ);
unlock:
<------>mutex_unlock(&aux->cec.lock);
}
EXPORT_SYMBOL(drm_dp_cec_irq);
 
static bool drm_dp_cec_cap(struct drm_dp_aux *aux, u8 *cec_cap)
{
<------>u8 cap = 0;
 
<------>if (drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_CAPABILITY, &cap) != 1 ||
<------>    !(cap & DP_CEC_TUNNELING_CAPABLE))
<------><------>return false;
<------>if (cec_cap)
<------><------>*cec_cap = cap;
<------>return true;
}
 
/*
 * Called if the HPD was low for more than drm_dp_cec_unregister_delay
 * seconds. This unregisters the CEC adapter.
 */
static void drm_dp_cec_unregister_work(struct work_struct *work)
{
<------>struct drm_dp_aux *aux = container_of(work, struct drm_dp_aux,
<------><------><------><------><------>      cec.unregister_work.work);
 
<------>mutex_lock(&aux->cec.lock);
<------>cec_unregister_adapter(aux->cec.adap);
<------>aux->cec.adap = NULL;
<------>mutex_unlock(&aux->cec.lock);
}
 
/*
 * A new EDID is set. If there is no CEC adapter, then create one. If
 * there was a CEC adapter, then check if the CEC adapter properties
 * were unchanged and just update the CEC physical address. Otherwise
 * unregister the old CEC adapter and create a new one.
 */
void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid)
{
<------>struct drm_connector *connector = aux->cec.connector;
<------>u32 cec_caps = CEC_CAP_DEFAULTS | CEC_CAP_NEEDS_HPD |
<------><------>       CEC_CAP_CONNECTOR_INFO;
<------>struct cec_connector_info conn_info;
<------>unsigned int num_las = 1;
<------>u8 cap;
 
<------>/* No transfer function was set, so not a DP connector */
<------>if (!aux->transfer)
<------><------>return;
 
#ifndef CONFIG_MEDIA_CEC_RC
<------>/*
<------> * CEC_CAP_RC is part of CEC_CAP_DEFAULTS, but it is stripped by
<------> * cec_allocate_adapter() if CONFIG_MEDIA_CEC_RC is undefined.
<------> *
<------> * Do this here as well to ensure the tests against cec_caps are
<------> * correct.
<------> */
<------>cec_caps &= ~CEC_CAP_RC;
#endif
<------>cancel_delayed_work_sync(&aux->cec.unregister_work);
 
<------>mutex_lock(&aux->cec.lock);
<------>if (!drm_dp_cec_cap(aux, &cap)) {
<------><------>/* CEC is not supported, unregister any existing adapter */
<------><------>cec_unregister_adapter(aux->cec.adap);
<------><------>aux->cec.adap = NULL;
<------><------>goto unlock;
<------>}
 
<------>if (cap & DP_CEC_SNOOPING_CAPABLE)
<------><------>cec_caps |= CEC_CAP_MONITOR_ALL;
<------>if (cap & DP_CEC_MULTIPLE_LA_CAPABLE)
<------><------>num_las = CEC_MAX_LOG_ADDRS;
 
<------>if (aux->cec.adap) {
<------><------>if (aux->cec.adap->capabilities == cec_caps &&
<------><------>    aux->cec.adap->available_log_addrs == num_las) {
<------><------><------>/* Unchanged, so just set the phys addr */
<------><------><------>cec_s_phys_addr_from_edid(aux->cec.adap, edid);
<------><------><------>goto unlock;
<------><------>}
<------><------>/*
<------><------> * The capabilities changed, so unregister the old
<------><------> * adapter first.
<------><------> */
<------><------>cec_unregister_adapter(aux->cec.adap);
<------>}
 
<------>/* Create a new adapter */
<------>aux->cec.adap = cec_allocate_adapter(&drm_dp_cec_adap_ops,
<------><------><------><------><------>     aux, connector->name, cec_caps,
<------><------><------><------><------>     num_las);
<------>if (IS_ERR(aux->cec.adap)) {
<------><------>aux->cec.adap = NULL;
<------><------>goto unlock;
<------>}
 
<------>cec_fill_conn_info_from_drm(&conn_info, connector);
<------>cec_s_conn_info(aux->cec.adap, &conn_info);
 
<------>if (cec_register_adapter(aux->cec.adap, connector->dev->dev)) {
<------><------>cec_delete_adapter(aux->cec.adap);
<------><------>aux->cec.adap = NULL;
<------>} else {
<------><------>/*
<------><------> * Update the phys addr for the new CEC adapter. When called
<------><------> * from drm_dp_cec_register_connector() edid == NULL, so in
<------><------> * that case the phys addr is just invalidated.
<------><------> */
<------><------>cec_s_phys_addr_from_edid(aux->cec.adap, edid);
<------>}
unlock:
<------>mutex_unlock(&aux->cec.lock);
}
EXPORT_SYMBOL(drm_dp_cec_set_edid);
 
/*
 * The EDID disappeared (likely because of the HPD going down).
 */
void drm_dp_cec_unset_edid(struct drm_dp_aux *aux)
{
<------>/* No transfer function was set, so not a DP connector */
<------>if (!aux->transfer)
<------><------>return;
 
<------>cancel_delayed_work_sync(&aux->cec.unregister_work);
 
<------>mutex_lock(&aux->cec.lock);
<------>if (!aux->cec.adap)
<------><------>goto unlock;
 
<------>cec_phys_addr_invalidate(aux->cec.adap);
<------>/*
<------> * We're done if we want to keep the CEC device
<------> * (drm_dp_cec_unregister_delay is >= NEVER_UNREG_DELAY) or if the
<------> * DPCD still indicates the CEC capability (expected for an integrated
<------> * HDMI branch device).
<------> */
<------>if (drm_dp_cec_unregister_delay < NEVER_UNREG_DELAY &&
<------>    !drm_dp_cec_cap(aux, NULL)) {
<------><------>/*
<------><------> * Unregister the CEC adapter after drm_dp_cec_unregister_delay
<------><------> * seconds. This to debounce short HPD off-and-on cycles from
<------><------> * displays.
<------><------> */
<------><------>schedule_delayed_work(&aux->cec.unregister_work,
<------><------><------><------>      drm_dp_cec_unregister_delay * HZ);
<------>}
unlock:
<------>mutex_unlock(&aux->cec.lock);
}
EXPORT_SYMBOL(drm_dp_cec_unset_edid);
 
/**
 * drm_dp_cec_register_connector() - register a new connector
 * @aux: DisplayPort AUX channel
 * @connector: drm connector
 *
 * A new connector was registered with associated CEC adapter name and
 * CEC adapter parent device. After registering the name and parent
 * drm_dp_cec_set_edid() is called to check if the connector supports
 * CEC and to register a CEC adapter if that is the case.
 */
void drm_dp_cec_register_connector(struct drm_dp_aux *aux,
<------><------><------><------>   struct drm_connector *connector)
{
<------>WARN_ON(aux->cec.adap);
<------>if (WARN_ON(!aux->transfer))
<------><------>return;
<------>aux->cec.connector = connector;
<------>INIT_DELAYED_WORK(&aux->cec.unregister_work,
<------><------><------>  drm_dp_cec_unregister_work);
}
EXPORT_SYMBOL(drm_dp_cec_register_connector);
 
/**
 * drm_dp_cec_unregister_connector() - unregister the CEC adapter, if any
 * @aux: DisplayPort AUX channel
 */
void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux)
{
<------>if (!aux->cec.adap)
<------><------>return;
<------>cancel_delayed_work_sync(&aux->cec.unregister_work);
<------>cec_unregister_adapter(aux->cec.adap);
<------>aux->cec.adap = NULL;
}
EXPORT_SYMBOL(drm_dp_cec_unregister_connector);