On Thu, May 25, 2017 at 05:06:25PM +0200, Hans Verkuil wrote:
> From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
>
> This adds support for the DisplayPort CEC-Tunneling-over-AUX
> feature that is part of the DisplayPort 1.3 standard.
>
> Unfortunately, not all DisplayPort/USB-C to HDMI adapters with a
> chip that has this capability actually hook up the CEC pin, so
> even though a CEC device is created, it may not actually work.
>
> Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
> ---
> drivers/gpu/drm/Kconfig | 3 +
> drivers/gpu/drm/Makefile | 1 +
> drivers/gpu/drm/drm_dp_cec.c | 196 +++++++++++++++++++++++++++++++++++++++++++
> include/drm/drm_dp_helper.h | 24 ++++++
> 4 files changed, 224 insertions(+)
> create mode 100644 drivers/gpu/drm/drm_dp_cec.c
>
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 78d7fc0ebb57..dd771ce8a3d0 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -120,6 +120,9 @@ config DRM_LOAD_EDID_FIRMWARE
> default case is N. Details and instructions how to build your own
> EDID data are given in Documentation/EDID/HOWTO.txt.
>
> +config DRM_DP_CEC
> + bool
We generally don't bother with a Kconfig for every little bit in drm, not
worth the trouble (yes I know there's some exceptions, but somehow they're
all from soc people). Just smash this into the KMS_HELPER one and live is
much easier for drivers. Also allows you to drop the dummy inline
functions.
The other nitpick: Pls kernel-doc the functions exported to drivers, and
then pull them into Documentation/gpu/drm-kms-helpers.rst, next to the
existing DP helper section.
Thanks, Daniel
> +
> config DRM_TTM
> tristate
> depends on DRM && MMU
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index 59f0f9b696eb..22f1a17dfc8a 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -34,6 +34,7 @@ drm_kms_helper-y := drm_crtc_helper.o drm_dp_helper.o drm_probe_helper.o \
> drm_simple_kms_helper.o drm_modeset_helper.o \
> drm_scdc_helper.o
>
> +drm_kms_helper-$(CONFIG_DRM_DP_CEC) += drm_dp_cec.o
> drm_kms_helper-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
> drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o
> drm_kms_helper-$(CONFIG_DRM_KMS_CMA_HELPER) += drm_fb_cma_helper.o
> diff --git a/drivers/gpu/drm/drm_dp_cec.c b/drivers/gpu/drm/drm_dp_cec.c
> new file mode 100644
> index 000000000000..44c544ba53cb
> --- /dev/null
> +++ b/drivers/gpu/drm/drm_dp_cec.c
> @@ -0,0 +1,196 @@
> +/*
> + * DisplayPort CEC-Tunneling-over-AUX support
> + *
> + * Copyright 2017 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
> + *
> + * This program is free software; you may redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; version 2 of the License.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
> + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
> + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
> + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
> + * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
> + * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
> + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
> + * SOFTWARE.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <drm/drm_dp_helper.h>
> +#include <media/cec.h>
> +
> +static int drm_dp_cec_adap_enable(struct cec_adapter *adap, bool enable)
> +{
> + struct drm_dp_aux *aux = cec_get_drvdata(adap);
> + ssize_t err = 0;
> +
> + if (enable)
> + err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL,
> + DP_CEC_TUNNELING_ENABLE);
> + else
> + err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, 0);
> + 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);
> + u8 mask[2] = { 0x00, 0x80 };
> + ssize_t err;
> +
> + if (addr != CEC_LOG_ADDR_INVALID) {
> + u16 la_mask = adap->log_addrs.log_addr_mask;
> +
> + la_mask |= 0x8000 | (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 = 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;
> +
> + if (retries > 5)
> + retries = 5;
> + 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 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,
> +};
> +
> +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;
> +}
> +
> +int drm_dp_cec_irq(struct drm_dp_aux *aux)
> +{
> + struct cec_adapter *adap = aux->cec_adap;
> + u8 flags;
> + ssize_t err;
> +
> + if (!aux->cec_adap)
> + return 0;
> +
> + err = drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, &flags);
> + if (err < 0)
> + return err;
> +
> + if (flags & DP_CEC_RX_MESSAGE_INFO_VALID)
> + drm_dp_cec_received(aux);
> +
> + if (flags & DP_CEC_TX_MESSAGE_SENT)
> + cec_transmit_done(adap, CEC_TX_STATUS_OK, 0, 0, 0, 0);
> + else if (flags & DP_CEC_TX_LINE_ERROR)
> + cec_transmit_done(adap, CEC_TX_STATUS_ERROR |
> + CEC_TX_STATUS_MAX_RETRIES, 0, 0, 0, 1);
> + else if (flags &
> + (DP_CEC_TX_ADDRESS_NACK_ERROR | DP_CEC_TX_DATA_NACK_ERROR))
> + cec_transmit_done(adap, CEC_TX_STATUS_NACK |
> + CEC_TX_STATUS_MAX_RETRIES, 0, 1, 0, 0);
> + drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, flags);
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_dp_cec_irq);
> +
> +int drm_dp_cec_configure_adapter(struct drm_dp_aux *aux, const char *name,
> + struct device *parent)
> +{
> + u32 cec_caps = CEC_CAP_LOG_ADDRS | CEC_CAP_TRANSMIT |
> + CEC_CAP_PASSTHROUGH | CEC_CAP_RC | CEC_CAP_NEEDS_HPD;
> + unsigned int num_las = 1;
> + int err;
> + u8 cap;
> +
> + if (drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_CAPABILITY, &cap) != 1 ||
> + !(cap & DP_CEC_TUNNELING_CAPABLE)) {
> + cec_unregister_adapter(aux->cec_adap);
> + aux->cec_adap = NULL;
> + return -ENODEV;
> + }
> +
> + 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 (!IS_ERR_OR_NULL(aux->cec_adap)) {
> + if (aux->cec_adap->capabilities == cec_caps &&
> + aux->cec_adap->available_log_addrs == num_las)
> + return 0;
> + cec_unregister_adapter(aux->cec_adap);
> + }
> +
> + aux->cec_adap = cec_allocate_adapter(&drm_dp_cec_adap_ops,
> + aux, name, cec_caps, num_las);
> + if (IS_ERR(aux->cec_adap)) {
> + err = PTR_ERR(aux->cec_adap);
> + aux->cec_adap = NULL;
> + return err;
> + }
> + err = cec_register_adapter(aux->cec_adap, parent);
> + if (err) {
> + cec_delete_adapter(aux->cec_adap);
> + aux->cec_adap = NULL;
> + }
> + return err;
> +}
> +EXPORT_SYMBOL(drm_dp_cec_configure_adapter);
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 3f4ad709534e..1e373df48108 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -843,6 +843,8 @@ struct drm_dp_aux_msg {
> size_t size;
> };
>
> +struct cec_adapter;
> +
> /**
> * struct drm_dp_aux - DisplayPort AUX channel
> * @name: user-visible name of this AUX channel and the I2C-over-AUX adapter
> @@ -901,6 +903,10 @@ struct drm_dp_aux {
> * @i2c_defer_count: Counts I2C DEFERs, used for DP validation.
> */
> unsigned i2c_defer_count;
> + /**
> + * @cec_adap: the CEC adapter for CEC-Tunneling-over-AUX support.
> + */
> + struct cec_adapter *cec_adap;
> };
>
> ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
> @@ -972,4 +978,22 @@ void drm_dp_aux_unregister(struct drm_dp_aux *aux);
> int drm_dp_start_crc(struct drm_dp_aux *aux, struct drm_crtc *crtc);
> int drm_dp_stop_crc(struct drm_dp_aux *aux);
>
> +#ifdef CONFIG_DRM_DP_CEC
> +int drm_dp_cec_irq(struct drm_dp_aux *aux);
> +int drm_dp_cec_configure_adapter(struct drm_dp_aux *aux, const char *name,
> + struct device *parent);
> +#else
> +static inline int drm_dp_cec_irq(struct drm_dp_aux *aux)
> +{
> + return 0;
> +}
> +
> +static inline int drm_dp_cec_configure_adapter(struct drm_dp_aux *aux,
> + const char *name,
> + struct device *parent)
> +{
> + return -ENODEV;
> +}
> +#endif
> +
> #endif /* _DRM_DP_HELPER_H_ */
> --
> 2.11.0
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
