drm/vc4: add HDMI CEC support

This patch adds support to VC4 for CEC.  It is under a separate
Kconfig option to keep everyone using VC4 from needing to pull in the
CEC core.

Thanks to Eric Anholt for providing me with the CEC register information.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20170716104804.48308-4-hverkuil@xs4all.nl

Author: Hans Verkuil

drivers/gpu/drm/vc4/Kconfig

@@ -19,3 +19,11 @@ config DRM_VC4
 	  This driver requires that "avoid_warnings=2" be present in
 	  the config.txt for the firmware, to keep it from smashing
 	  our display setup.
+
+config DRM_VC4_HDMI_CEC
+       bool "Broadcom VC4 HDMI CEC Support"
+       depends on DRM_VC4
+       select CEC_CORE
+       help
+	  Choose this option if you have a Broadcom VC4 GPU
+	  and want to use CEC.

drivers/gpu/drm/vc4/vc4_hdmi.c

@@ -57,9 +57,14 @@
 #include <sound/pcm_drm_eld.h>
 #include <sound/pcm_params.h>
 #include <sound/soc.h>
+#include "media/cec.h"
 #include "vc4_drv.h"
 #include "vc4_regs.h"
 
+#define HSM_CLOCK_FREQ 163682864
+#define CEC_CLOCK_FREQ 40000
+#define CEC_CLOCK_DIV  (HSM_CLOCK_FREQ / CEC_CLOCK_FREQ)
+
 /* HDMI audio information */
 struct vc4_hdmi_audio {
 	struct snd_soc_card card;
@@ -85,6 +90,11 @@ struct vc4_hdmi {
 	int hpd_gpio;
 	bool hpd_active_low;
 
+	struct cec_adapter *cec_adap;
+	struct cec_msg cec_rx_msg;
+	bool cec_tx_ok;
+	bool cec_irq_was_rx;
+
 	struct clk *pixel_clock;
 	struct clk *hsm_clock;
 };
@@ -149,6 +159,23 @@ static const struct {
 	HDMI_REG(VC4_HDMI_VERTB1),
 	HDMI_REG(VC4_HDMI_TX_PHY_RESET_CTL),
 	HDMI_REG(VC4_HDMI_TX_PHY_CTL0),
+
+	HDMI_REG(VC4_HDMI_CEC_CNTRL_1),
+	HDMI_REG(VC4_HDMI_CEC_CNTRL_2),
+	HDMI_REG(VC4_HDMI_CEC_CNTRL_3),
+	HDMI_REG(VC4_HDMI_CEC_CNTRL_4),
+	HDMI_REG(VC4_HDMI_CEC_CNTRL_5),
+	HDMI_REG(VC4_HDMI_CPU_STATUS),
+	HDMI_REG(VC4_HDMI_CPU_MASK_STATUS),
+
+	HDMI_REG(VC4_HDMI_CEC_RX_DATA_1),
+	HDMI_REG(VC4_HDMI_CEC_RX_DATA_2),
+	HDMI_REG(VC4_HDMI_CEC_RX_DATA_3),
+	HDMI_REG(VC4_HDMI_CEC_RX_DATA_4),
+	HDMI_REG(VC4_HDMI_CEC_TX_DATA_1),
+	HDMI_REG(VC4_HDMI_CEC_TX_DATA_2),
+	HDMI_REG(VC4_HDMI_CEC_TX_DATA_3),
+	HDMI_REG(VC4_HDMI_CEC_TX_DATA_4),
 };
 
 static const struct {
@@ -216,17 +243,17 @@ vc4_hdmi_connector_detect(struct drm_connector *connector, bool force)
 		if (gpio_get_value_cansleep(vc4->hdmi->hpd_gpio) ^
 		    vc4->hdmi->hpd_active_low)
 			return connector_status_connected;
-		else
-			return connector_status_disconnected;
+		cec_phys_addr_invalidate(vc4->hdmi->cec_adap);
+		return connector_status_disconnected;
 	}
 
 	if (drm_probe_ddc(vc4->hdmi->ddc))
 		return connector_status_connected;
 
 	if (HDMI_READ(VC4_HDMI_HOTPLUG) & VC4_HDMI_HOTPLUG_CONNECTED)
 		return connector_status_connected;
-	else
-		return connector_status_disconnected;
+	cec_phys_addr_invalidate(vc4->hdmi->cec_adap);
+	return connector_status_disconnected;
 }
 
 static void vc4_hdmi_connector_destroy(struct drm_connector *connector)
@@ -247,6 +274,7 @@ static int vc4_hdmi_connector_get_modes(struct drm_connector *connector)
 	struct edid *edid;
 
 	edid = drm_get_edid(connector, vc4->hdmi->ddc);
+	cec_s_phys_addr_from_edid(vc4->hdmi->cec_adap, edid);
 	if (!edid)
 		return -ENODEV;
 
@@ -1121,6 +1149,159 @@ static void vc4_hdmi_audio_cleanup(struct vc4_hdmi *hdmi)
 		snd_soc_unregister_codec(dev);
 }
 
+#ifdef CONFIG_DRM_VC4_HDMI_CEC
+static irqreturn_t vc4_cec_irq_handler_thread(int irq, void *priv)
+{
+	struct vc4_dev *vc4 = priv;
+	struct vc4_hdmi *hdmi = vc4->hdmi;
+
+	if (hdmi->cec_irq_was_rx) {
+		if (hdmi->cec_rx_msg.len)
+			cec_received_msg(hdmi->cec_adap, &hdmi->cec_rx_msg);
+	} else if (hdmi->cec_tx_ok) {
+		cec_transmit_done(hdmi->cec_adap, CEC_TX_STATUS_OK,
+				  0, 0, 0, 0);
+	} else {
+		/*
+		 * This CEC implementation makes 1 retry, so if we
+		 * get a NACK, then that means it made 2 attempts.
+		 */
+		cec_transmit_done(hdmi->cec_adap, CEC_TX_STATUS_NACK,
+				  0, 2, 0, 0);
+	}
+	return IRQ_HANDLED;
+}
+
+static void vc4_cec_read_msg(struct vc4_dev *vc4, u32 cntrl1)
+{
+	struct cec_msg *msg = &vc4->hdmi->cec_rx_msg;
+	unsigned int i;
+
+	msg->len = 1 + ((cntrl1 & VC4_HDMI_CEC_REC_WRD_CNT_MASK) >>
+					VC4_HDMI_CEC_REC_WRD_CNT_SHIFT);
+	for (i = 0; i < msg->len; i += 4) {
+		u32 val = HDMI_READ(VC4_HDMI_CEC_RX_DATA_1 + i);
+
+		msg->msg[i] = val & 0xff;
+		msg->msg[i + 1] = (val >> 8) & 0xff;
+		msg->msg[i + 2] = (val >> 16) & 0xff;
+		msg->msg[i + 3] = (val >> 24) & 0xff;
+	}
+}
+
+static irqreturn_t vc4_cec_irq_handler(int irq, void *priv)
+{
+	struct vc4_dev *vc4 = priv;
+	struct vc4_hdmi *hdmi = vc4->hdmi;
+	u32 stat = HDMI_READ(VC4_HDMI_CPU_STATUS);
+	u32 cntrl1, cntrl5;
+
+	if (!(stat & VC4_HDMI_CPU_CEC))
+		return IRQ_NONE;
+	hdmi->cec_rx_msg.len = 0;
+	cntrl1 = HDMI_READ(VC4_HDMI_CEC_CNTRL_1);
+	cntrl5 = HDMI_READ(VC4_HDMI_CEC_CNTRL_5);
+	hdmi->cec_irq_was_rx = cntrl5 & VC4_HDMI_CEC_RX_CEC_INT;
+	if (hdmi->cec_irq_was_rx) {
+		vc4_cec_read_msg(vc4, cntrl1);
+		cntrl1 |= VC4_HDMI_CEC_CLEAR_RECEIVE_OFF;
+		HDMI_WRITE(VC4_HDMI_CEC_CNTRL_1, cntrl1);
+		cntrl1 &= ~VC4_HDMI_CEC_CLEAR_RECEIVE_OFF;
+	} else {
+		hdmi->cec_tx_ok = cntrl1 & VC4_HDMI_CEC_TX_STATUS_GOOD;
+		cntrl1 &= ~VC4_HDMI_CEC_START_XMIT_BEGIN;
+	}
+	HDMI_WRITE(VC4_HDMI_CEC_CNTRL_1, cntrl1);
+	HDMI_WRITE(VC4_HDMI_CPU_CLEAR, VC4_HDMI_CPU_CEC);
+
+	return IRQ_WAKE_THREAD;
+}
+
+static int vc4_hdmi_cec_adap_enable(struct cec_adapter *adap, bool enable)
+{
+	struct vc4_dev *vc4 = cec_get_drvdata(adap);
+	/* clock period in microseconds */
+	const u32 usecs = 1000000 / CEC_CLOCK_FREQ;
+	u32 val = HDMI_READ(VC4_HDMI_CEC_CNTRL_5);
+
+	val &= ~(VC4_HDMI_CEC_TX_SW_RESET | VC4_HDMI_CEC_RX_SW_RESET |
+		 VC4_HDMI_CEC_CNT_TO_4700_US_MASK |
+		 VC4_HDMI_CEC_CNT_TO_4500_US_MASK);
+	val |= ((4700 / usecs) << VC4_HDMI_CEC_CNT_TO_4700_US_SHIFT) |
+	       ((4500 / usecs) << VC4_HDMI_CEC_CNT_TO_4500_US_SHIFT);
+
+	if (enable) {
+		HDMI_WRITE(VC4_HDMI_CEC_CNTRL_5, val |
+			   VC4_HDMI_CEC_TX_SW_RESET | VC4_HDMI_CEC_RX_SW_RESET);
+		HDMI_WRITE(VC4_HDMI_CEC_CNTRL_5, val);
+		HDMI_WRITE(VC4_HDMI_CEC_CNTRL_2,
+			 ((1500 / usecs) << VC4_HDMI_CEC_CNT_TO_1500_US_SHIFT) |
+			 ((1300 / usecs) << VC4_HDMI_CEC_CNT_TO_1300_US_SHIFT) |
+			 ((800 / usecs) << VC4_HDMI_CEC_CNT_TO_800_US_SHIFT) |
+			 ((600 / usecs) << VC4_HDMI_CEC_CNT_TO_600_US_SHIFT) |
+			 ((400 / usecs) << VC4_HDMI_CEC_CNT_TO_400_US_SHIFT));
+		HDMI_WRITE(VC4_HDMI_CEC_CNTRL_3,
+			 ((2750 / usecs) << VC4_HDMI_CEC_CNT_TO_2750_US_SHIFT) |
+			 ((2400 / usecs) << VC4_HDMI_CEC_CNT_TO_2400_US_SHIFT) |
+			 ((2050 / usecs) << VC4_HDMI_CEC_CNT_TO_2050_US_SHIFT) |
+			 ((1700 / usecs) << VC4_HDMI_CEC_CNT_TO_1700_US_SHIFT));
+		HDMI_WRITE(VC4_HDMI_CEC_CNTRL_4,
+			 ((4300 / usecs) << VC4_HDMI_CEC_CNT_TO_4300_US_SHIFT) |
+			 ((3900 / usecs) << VC4_HDMI_CEC_CNT_TO_3900_US_SHIFT) |
+			 ((3600 / usecs) << VC4_HDMI_CEC_CNT_TO_3600_US_SHIFT) |
+			 ((3500 / usecs) << VC4_HDMI_CEC_CNT_TO_3500_US_SHIFT));
+
+		HDMI_WRITE(VC4_HDMI_CPU_MASK_CLEAR, VC4_HDMI_CPU_CEC);
+	} else {
+		HDMI_WRITE(VC4_HDMI_CPU_MASK_SET, VC4_HDMI_CPU_CEC);
+		HDMI_WRITE(VC4_HDMI_CEC_CNTRL_5, val |
+			   VC4_HDMI_CEC_TX_SW_RESET | VC4_HDMI_CEC_RX_SW_RESET);
+	}
+	return 0;
+}
+
+static int vc4_hdmi_cec_adap_log_addr(struct cec_adapter *adap, u8 log_addr)
+{
+	struct vc4_dev *vc4 = cec_get_drvdata(adap);
+
+	HDMI_WRITE(VC4_HDMI_CEC_CNTRL_1,
+		   (HDMI_READ(VC4_HDMI_CEC_CNTRL_1) & ~VC4_HDMI_CEC_ADDR_MASK) |
+		   (log_addr & 0xf) << VC4_HDMI_CEC_ADDR_SHIFT);
+	return 0;
+}
+
+static int vc4_hdmi_cec_adap_transmit(struct cec_adapter *adap, u8 attempts,
+				      u32 signal_free_time, struct cec_msg *msg)
+{
+	struct vc4_dev *vc4 = cec_get_drvdata(adap);
+	u32 val;
+	unsigned int i;
+
+	for (i = 0; i < msg->len; i += 4)
+		HDMI_WRITE(VC4_HDMI_CEC_TX_DATA_1 + i,
+			   (msg->msg[i]) |
+			   (msg->msg[i + 1] << 8) |
+			   (msg->msg[i + 2] << 16) |
+			   (msg->msg[i + 3] << 24));
+
+	val = HDMI_READ(VC4_HDMI_CEC_CNTRL_1);
+	val &= ~VC4_HDMI_CEC_START_XMIT_BEGIN;
+	HDMI_WRITE(VC4_HDMI_CEC_CNTRL_1, val);
+	val &= ~VC4_HDMI_CEC_MESSAGE_LENGTH_MASK;
+	val |= (msg->len - 1) << VC4_HDMI_CEC_MESSAGE_LENGTH_SHIFT;
+	val |= VC4_HDMI_CEC_START_XMIT_BEGIN;
+
+	HDMI_WRITE(VC4_HDMI_CEC_CNTRL_1, val);
+	return 0;
+}
+
+static const struct cec_adap_ops vc4_hdmi_cec_adap_ops = {
+	.adap_enable = vc4_hdmi_cec_adap_enable,
+	.adap_log_addr = vc4_hdmi_cec_adap_log_addr,
+	.adap_transmit = vc4_hdmi_cec_adap_transmit,
+};
+#endif
+
 static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
 {
 	struct platform_device *pdev = to_platform_device(dev);
@@ -1180,7 +1361,7 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
 	 * needs to be a bit higher than the pixel clock rate
 	 * (generally 148.5Mhz).
 	 */
-	ret = clk_set_rate(hdmi->hsm_clock, 163682864);
+	ret = clk_set_rate(hdmi->hsm_clock, HSM_CLOCK_FREQ);
 	if (ret) {
 		DRM_ERROR("Failed to set HSM clock rate: %d\n", ret);
 		goto err_put_i2c;
@@ -1231,13 +1412,50 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
 		ret = PTR_ERR(hdmi->connector);
 		goto err_destroy_encoder;
 	}
+#ifdef CONFIG_DRM_VC4_HDMI_CEC
+	hdmi->cec_adap = cec_allocate_adapter(&vc4_hdmi_cec_adap_ops,
+					      vc4, "vc4",
+					      CEC_CAP_TRANSMIT |
+					      CEC_CAP_LOG_ADDRS |
+					      CEC_CAP_PASSTHROUGH |
+					      CEC_CAP_RC, 1);
+	ret = PTR_ERR_OR_ZERO(hdmi->cec_adap);
+	if (ret < 0)
+		goto err_destroy_conn;
+	HDMI_WRITE(VC4_HDMI_CPU_MASK_SET, 0xffffffff);
+	value = HDMI_READ(VC4_HDMI_CEC_CNTRL_1);
+	value &= ~VC4_HDMI_CEC_DIV_CLK_CNT_MASK;
+	/*
+	 * Set the logical address to Unregistered and set the clock
+	 * divider: the hsm_clock rate and this divider setting will
+	 * give a 40 kHz CEC clock.
+	 */
+	value |= VC4_HDMI_CEC_ADDR_MASK |
+		 (4091 << VC4_HDMI_CEC_DIV_CLK_CNT_SHIFT);
+	HDMI_WRITE(VC4_HDMI_CEC_CNTRL_1, value);
+	ret = devm_request_threaded_irq(dev, platform_get_irq(pdev, 0),
+					vc4_cec_irq_handler,
+					vc4_cec_irq_handler_thread, 0,
+					"vc4 hdmi cec", vc4);
+	if (ret)
+		goto err_delete_cec_adap;
+	ret = cec_register_adapter(hdmi->cec_adap, dev);
+	if (ret < 0)
+		goto err_delete_cec_adap;
+#endif
 
 	ret = vc4_hdmi_audio_init(hdmi);
 	if (ret)
 		goto err_destroy_encoder;
 
 	return 0;
 
+#ifdef CONFIG_DRM_VC4_HDMI_CEC
+err_delete_cec_adap:
+	cec_delete_adapter(hdmi->cec_adap);
+err_destroy_conn:
+	vc4_hdmi_connector_destroy(hdmi->connector);
+#endif
 err_destroy_encoder:
 	vc4_hdmi_encoder_destroy(hdmi->encoder);
 err_unprepare_hsm:
@@ -1257,7 +1475,7 @@ static void vc4_hdmi_unbind(struct device *dev, struct device *master,
 	struct vc4_hdmi *hdmi = vc4->hdmi;
 
 	vc4_hdmi_audio_cleanup(hdmi);
-
+	cec_unregister_adapter(hdmi->cec_adap);
 	vc4_hdmi_connector_destroy(hdmi->connector);
 	vc4_hdmi_encoder_destroy(hdmi->encoder);