drm/bridge: dw-hdmi: add cec driver

Add a CEC driver for the dw-hdmi hardware.
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
[hans.verkuil: unsigned -> unsigned int]
[hans.verkuil: cec_transmit_done -> cec_transmit_attempt_done]
[hans.verkuil: add missing CEC_CAP_PASSTHROUGH]
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Tested-by: Hans Verkuil <hans.verkuil@cisco.com>
Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20170802184108.7913-4-hverkuil@xs4all.nl

drivers/gpu/drm/bridge/synopsys/Kconfig

@@ -24,6 +24,15 @@ config DRM_DW_HDMI_I2S_AUDIO
 	  Support the I2S Audio interface which is part of the Synopsys
 	  Designware HDMI block.
 
+config DRM_DW_HDMI_CEC
+	tristate "Synopsis Designware CEC interface"
+	depends on DRM_DW_HDMI
+	select CEC_CORE
+	select CEC_NOTIFIER
+	help
+	  Support the CE interface which is part of the Synopsys
+	  Designware HDMI block.
+
 config DRM_DW_MIPI_DSI
 	tristate
 	select DRM_KMS_HELPER

drivers/gpu/drm/bridge/synopsys/Makefile

@@ -3,5 +3,6 @@
 obj-$(CONFIG_DRM_DW_HDMI) += dw-hdmi.o
 obj-$(CONFIG_DRM_DW_HDMI_AHB_AUDIO) += dw-hdmi-ahb-audio.o
 obj-$(CONFIG_DRM_DW_HDMI_I2S_AUDIO) += dw-hdmi-i2s-audio.o
+obj-$(CONFIG_DRM_DW_HDMI_CEC) += dw-hdmi-cec.o
 
 obj-$(CONFIG_DRM_DW_MIPI_DSI) += dw-mipi-dsi.o

drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.c

+/*
+ * Designware HDMI CEC driver
+ *
+ * Copyright (C) 2015-2017 Russell King.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+#include <drm/drm_edid.h>
+
+#include <media/cec.h>
+#include <media/cec-notifier.h>
+
+#include "dw-hdmi-cec.h"
+
+enum {
+	HDMI_IH_CEC_STAT0	= 0x0106,
+	HDMI_IH_MUTE_CEC_STAT0	= 0x0186,
+
+	HDMI_CEC_CTRL		= 0x7d00,
+	CEC_CTRL_START		= BIT(0),
+	CEC_CTRL_FRAME_TYP	= 3 << 1,
+	CEC_CTRL_RETRY		= 0 << 1,
+	CEC_CTRL_NORMAL		= 1 << 1,
+	CEC_CTRL_IMMED		= 2 << 1,
+
+	HDMI_CEC_STAT		= 0x7d01,
+	CEC_STAT_DONE		= BIT(0),
+	CEC_STAT_EOM		= BIT(1),
+	CEC_STAT_NACK		= BIT(2),
+	CEC_STAT_ARBLOST	= BIT(3),
+	CEC_STAT_ERROR_INIT	= BIT(4),
+	CEC_STAT_ERROR_FOLL	= BIT(5),
+	CEC_STAT_WAKEUP		= BIT(6),
+
+	HDMI_CEC_MASK		= 0x7d02,
+	HDMI_CEC_POLARITY	= 0x7d03,
+	HDMI_CEC_INT		= 0x7d04,
+	HDMI_CEC_ADDR_L		= 0x7d05,
+	HDMI_CEC_ADDR_H		= 0x7d06,
+	HDMI_CEC_TX_CNT		= 0x7d07,
+	HDMI_CEC_RX_CNT		= 0x7d08,
+	HDMI_CEC_TX_DATA0	= 0x7d10,
+	HDMI_CEC_RX_DATA0	= 0x7d20,
+	HDMI_CEC_LOCK		= 0x7d30,
+	HDMI_CEC_WKUPCTRL	= 0x7d31,
+};
+
+struct dw_hdmi_cec {
+	struct dw_hdmi *hdmi;
+	const struct dw_hdmi_cec_ops *ops;
+	u32 addresses;
+	struct cec_adapter *adap;
+	struct cec_msg rx_msg;
+	unsigned int tx_status;
+	bool tx_done;
+	bool rx_done;
+	struct cec_notifier *notify;
+	int irq;
+};
+
+static void dw_hdmi_write(struct dw_hdmi_cec *cec, u8 val, int offset)
+{
+	cec->ops->write(cec->hdmi, val, offset);
+}
+
+static u8 dw_hdmi_read(struct dw_hdmi_cec *cec, int offset)
+{
+	return cec->ops->read(cec->hdmi, offset);
+}
+
+static int dw_hdmi_cec_log_addr(struct cec_adapter *adap, u8 logical_addr)
+{
+	struct dw_hdmi_cec *cec = cec_get_drvdata(adap);
+
+	if (logical_addr == CEC_LOG_ADDR_INVALID)
+		cec->addresses = 0;
+	else
+		cec->addresses |= BIT(logical_addr) | BIT(15);
+
+	dw_hdmi_write(cec, cec->addresses & 255, HDMI_CEC_ADDR_L);
+	dw_hdmi_write(cec, cec->addresses >> 8, HDMI_CEC_ADDR_H);
+
+	return 0;
+}
+
+static int dw_hdmi_cec_transmit(struct cec_adapter *adap, u8 attempts,
+				u32 signal_free_time, struct cec_msg *msg)
+{
+	struct dw_hdmi_cec *cec = cec_get_drvdata(adap);
+	unsigned int i, ctrl;
+
+	switch (signal_free_time) {
+	case CEC_SIGNAL_FREE_TIME_RETRY:
+		ctrl = CEC_CTRL_RETRY;
+		break;
+	case CEC_SIGNAL_FREE_TIME_NEW_INITIATOR:
+	default:
+		ctrl = CEC_CTRL_NORMAL;
+		break;
+	case CEC_SIGNAL_FREE_TIME_NEXT_XFER:
+		ctrl = CEC_CTRL_IMMED;
+		break;
+	}
+
+	for (i = 0; i < msg->len; i++)
+		dw_hdmi_write(cec, msg->msg[i], HDMI_CEC_TX_DATA0 + i);
+
+	dw_hdmi_write(cec, msg->len, HDMI_CEC_TX_CNT);
+	dw_hdmi_write(cec, ctrl | CEC_CTRL_START, HDMI_CEC_CTRL);
+
+	return 0;
+}
+
+static irqreturn_t dw_hdmi_cec_hardirq(int irq, void *data)
+{
+	struct cec_adapter *adap = data;
+	struct dw_hdmi_cec *cec = cec_get_drvdata(adap);
+	unsigned int stat = dw_hdmi_read(cec, HDMI_IH_CEC_STAT0);
+	irqreturn_t ret = IRQ_HANDLED;
+
+	if (stat == 0)
+		return IRQ_NONE;
+
+	dw_hdmi_write(cec, stat, HDMI_IH_CEC_STAT0);
+
+	if (stat & CEC_STAT_ERROR_INIT) {
+		cec->tx_status = CEC_TX_STATUS_ERROR;
+		cec->tx_done = true;
+		ret = IRQ_WAKE_THREAD;
+	} else if (stat & CEC_STAT_DONE) {
+		cec->tx_status = CEC_TX_STATUS_OK;
+		cec->tx_done = true;
+		ret = IRQ_WAKE_THREAD;
+	} else if (stat & CEC_STAT_NACK) {
+		cec->tx_status = CEC_TX_STATUS_NACK;
+		cec->tx_done = true;
+		ret = IRQ_WAKE_THREAD;
+	}
+
+	if (stat & CEC_STAT_EOM) {
+		unsigned int len, i;
+
+		len = dw_hdmi_read(cec, HDMI_CEC_RX_CNT);
+		if (len > sizeof(cec->rx_msg.msg))
+			len = sizeof(cec->rx_msg.msg);
+
+		for (i = 0; i < len; i++)
+			cec->rx_msg.msg[i] =
+				dw_hdmi_read(cec, HDMI_CEC_RX_DATA0 + i);
+
+		dw_hdmi_write(cec, 0, HDMI_CEC_LOCK);
+
+		cec->rx_msg.len = len;
+		smp_wmb();
+		cec->rx_done = true;
+
+		ret = IRQ_WAKE_THREAD;
+	}
+
+	return ret;
+}
+
+static irqreturn_t dw_hdmi_cec_thread(int irq, void *data)
+{
+	struct cec_adapter *adap = data;
+	struct dw_hdmi_cec *cec = cec_get_drvdata(adap);
+
+	if (cec->tx_done) {
+		cec->tx_done = false;
+		cec_transmit_attempt_done(adap, cec->tx_status);
+	}
+	if (cec->rx_done) {
+		cec->rx_done = false;
+		smp_rmb();
+		cec_received_msg(adap, &cec->rx_msg);
+	}
+	return IRQ_HANDLED;
+}
+
+static int dw_hdmi_cec_enable(struct cec_adapter *adap, bool enable)
+{
+	struct dw_hdmi_cec *cec = cec_get_drvdata(adap);
+
+	if (!enable) {
+		dw_hdmi_write(cec, ~0, HDMI_CEC_MASK);
+		dw_hdmi_write(cec, ~0, HDMI_IH_MUTE_CEC_STAT0);
+		dw_hdmi_write(cec, 0, HDMI_CEC_POLARITY);
+
+		cec->ops->disable(cec->hdmi);
+	} else {
+		unsigned int irqs;
+
+		dw_hdmi_write(cec, 0, HDMI_CEC_CTRL);
+		dw_hdmi_write(cec, ~0, HDMI_IH_CEC_STAT0);
+		dw_hdmi_write(cec, 0, HDMI_CEC_LOCK);
+
+		dw_hdmi_cec_log_addr(cec->adap, CEC_LOG_ADDR_INVALID);
+
+		cec->ops->enable(cec->hdmi);
+
+		irqs = CEC_STAT_ERROR_INIT | CEC_STAT_NACK | CEC_STAT_EOM |
+		       CEC_STAT_DONE;
+		dw_hdmi_write(cec, irqs, HDMI_CEC_POLARITY);
+		dw_hdmi_write(cec, ~irqs, HDMI_CEC_MASK);
+		dw_hdmi_write(cec, ~irqs, HDMI_IH_MUTE_CEC_STAT0);
+	}
+	return 0;
+}
+
+static const struct cec_adap_ops dw_hdmi_cec_ops = {
+	.adap_enable = dw_hdmi_cec_enable,
+	.adap_log_addr = dw_hdmi_cec_log_addr,
+	.adap_transmit = dw_hdmi_cec_transmit,
+};
+
+static void dw_hdmi_cec_del(void *data)
+{
+	struct dw_hdmi_cec *cec = data;
+
+	cec_delete_adapter(cec->adap);
+}
+
+static int dw_hdmi_cec_probe(struct platform_device *pdev)
+{
+	struct dw_hdmi_cec_data *data = dev_get_platdata(&pdev->dev);
+	struct dw_hdmi_cec *cec;
+	int ret;
+
+	if (!data)
+		return -ENXIO;
+
+	/*
+	 * Our device is just a convenience - we want to link to the real
+	 * hardware device here, so that userspace can see the association
+	 * between the HDMI hardware and its associated CEC chardev.
+	 */
+	cec = devm_kzalloc(&pdev->dev, sizeof(*cec), GFP_KERNEL);
+	if (!cec)
+		return -ENOMEM;
+
+	cec->irq = data->irq;
+	cec->ops = data->ops;
+	cec->hdmi = data->hdmi;
+
+	platform_set_drvdata(pdev, cec);
+
+	dw_hdmi_write(cec, 0, HDMI_CEC_TX_CNT);
+	dw_hdmi_write(cec, ~0, HDMI_CEC_MASK);
+	dw_hdmi_write(cec, ~0, HDMI_IH_MUTE_CEC_STAT0);
+	dw_hdmi_write(cec, 0, HDMI_CEC_POLARITY);
+
+	cec->adap = cec_allocate_adapter(&dw_hdmi_cec_ops, cec, "dw_hdmi",
+					 CEC_CAP_LOG_ADDRS | CEC_CAP_TRANSMIT |
+					 CEC_CAP_RC | CEC_CAP_PASSTHROUGH,
+					 CEC_MAX_LOG_ADDRS);
+	if (IS_ERR(cec->adap))
+		return PTR_ERR(cec->adap);
+
+	/* override the module pointer */
+	cec->adap->owner = THIS_MODULE;
+
+	ret = devm_add_action(&pdev->dev, dw_hdmi_cec_del, cec);
+	if (ret) {
+		cec_delete_adapter(cec->adap);
+		return ret;
+	}
+
+	ret = devm_request_threaded_irq(&pdev->dev, cec->irq,
+					dw_hdmi_cec_hardirq,
+					dw_hdmi_cec_thread, IRQF_SHARED,
+					"dw-hdmi-cec", cec->adap);
+	if (ret < 0)
+		return ret;
+
+	cec->notify = cec_notifier_get(pdev->dev.parent);
+	if (!cec->notify)
+		return -ENOMEM;
+
+	ret = cec_register_adapter(cec->adap, pdev->dev.parent);
+	if (ret < 0) {
+		cec_notifier_put(cec->notify);
+		return ret;
+	}
+
+	/*
+	 * CEC documentation says we must not call cec_delete_adapter
+	 * after a successful call to cec_register_adapter().
+	 */
+	devm_remove_action(&pdev->dev, dw_hdmi_cec_del, cec);
+
+	cec_register_cec_notifier(cec->adap, cec->notify);
+
+	return 0;
+}
+
+static int dw_hdmi_cec_remove(struct platform_device *pdev)
+{
+	struct dw_hdmi_cec *cec = platform_get_drvdata(pdev);
+
+	cec_unregister_adapter(cec->adap);
+	cec_notifier_put(cec->notify);
+
+	return 0;
+}
+
+static struct platform_driver dw_hdmi_cec_driver = {
+	.probe	= dw_hdmi_cec_probe,
+	.remove	= dw_hdmi_cec_remove,
+	.driver = {
+		.name = "dw-hdmi-cec",
+	},
+};
+module_platform_driver(dw_hdmi_cec_driver);
+
+MODULE_AUTHOR("Russell King <rmk+kernel@armlinux.org.uk>");
+MODULE_DESCRIPTION("Synopsys Designware HDMI CEC driver for i.MX");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS(PLATFORM_MODULE_PREFIX "dw-hdmi-cec");

drivers/gpu/drm/bridge/synopsys/dw-hdmi-cec.h

+#ifndef DW_HDMI_CEC_H
+#define DW_HDMI_CEC_H
+
+struct dw_hdmi;
+
+struct dw_hdmi_cec_ops {
+	void (*write)(struct dw_hdmi *hdmi, u8 val, int offset);
+	u8 (*read)(struct dw_hdmi *hdmi, int offset);
+	void (*enable)(struct dw_hdmi *hdmi);
+	void (*disable)(struct dw_hdmi *hdmi);
+};
+
+struct dw_hdmi_cec_data {
+	struct dw_hdmi *hdmi;
+	const struct dw_hdmi_cec_ops *ops;
+	int irq;
+};
+
+#endif

drivers/gpu/drm/bridge/synopsys/dw-hdmi.c

@@ -35,6 +35,7 @@
 
 #include "dw-hdmi.h"
 #include "dw-hdmi-audio.h"
+#include "dw-hdmi-cec.h"
 
 #include <media/cec-notifier.h>
 
@@ -133,6 +134,7 @@ struct dw_hdmi {
 	unsigned int version;
 
 	struct platform_device *audio;
+	struct platform_device *cec;
 	struct device *dev;
 	struct clk *isfr_clk;
 	struct clk *iahb_clk;
@@ -1794,7 +1796,6 @@ static void initialize_hdmi_ih_mutes(struct dw_hdmi *hdmi)
 	hdmi_writeb(hdmi, 0xff, HDMI_AUD_HBR_MASK);
 	hdmi_writeb(hdmi, 0xff, HDMI_GP_MASK);
 	hdmi_writeb(hdmi, 0xff, HDMI_A_APIINTMSK);
-	hdmi_writeb(hdmi, 0xff, HDMI_CEC_MASK);
 	hdmi_writeb(hdmi, 0xff, HDMI_I2CM_INT);
 	hdmi_writeb(hdmi, 0xff, HDMI_I2CM_CTLINT);
 
@@ -2236,6 +2237,29 @@ static int dw_hdmi_detect_phy(struct dw_hdmi *hdmi)
 	return -ENODEV;
 }
 
+static void dw_hdmi_cec_enable(struct dw_hdmi *hdmi)
+{
+	mutex_lock(&hdmi->mutex);
+	hdmi->mc_clkdis &= ~HDMI_MC_CLKDIS_CECCLK_DISABLE;
+	hdmi_writeb(hdmi, hdmi->mc_clkdis, HDMI_MC_CLKDIS);
+	mutex_unlock(&hdmi->mutex);
+}
+
+static void dw_hdmi_cec_disable(struct dw_hdmi *hdmi)
+{
+	mutex_lock(&hdmi->mutex);
+	hdmi->mc_clkdis |= HDMI_MC_CLKDIS_CECCLK_DISABLE;
+	hdmi_writeb(hdmi, hdmi->mc_clkdis, HDMI_MC_CLKDIS);
+	mutex_unlock(&hdmi->mutex);
+}
+
+static const struct dw_hdmi_cec_ops dw_hdmi_cec_ops = {
+	.write = hdmi_writeb,
+	.read = hdmi_readb,
+	.enable = dw_hdmi_cec_enable,
+	.disable = dw_hdmi_cec_disable,
+};
+
 static const struct regmap_config hdmi_regmap_8bit_config = {
 	.reg_bits	= 32,
 	.val_bits	= 8,
@@ -2258,6 +2282,7 @@ __dw_hdmi_probe(struct platform_device *pdev,
 	struct device_node *np = dev->of_node;
 	struct platform_device_info pdevinfo;
 	struct device_node *ddc_node;
+	struct dw_hdmi_cec_data cec;
 	struct dw_hdmi *hdmi;
 	struct resource *iores = NULL;
 	int irq;
@@ -2462,6 +2487,19 @@ __dw_hdmi_probe(struct platform_device *pdev,
 		hdmi->audio = platform_device_register_full(&pdevinfo);
 	}
 
+	if (config0 & HDMI_CONFIG0_CEC) {
+		cec.hdmi = hdmi;
+		cec.ops = &dw_hdmi_cec_ops;
+		cec.irq = irq;
+
+		pdevinfo.name = "dw-hdmi-cec";
+		pdevinfo.data = &cec;
+		pdevinfo.size_data = sizeof(cec);
+		pdevinfo.dma_mask = 0;
+
+		hdmi->cec = platform_device_register_full(&pdevinfo);
+	}
+
 	/* Reset HDMI DDC I2C master controller and mute I2CM interrupts */
 	if (hdmi->i2c)
 		dw_hdmi_i2c_init(hdmi);
@@ -2492,6 +2530,8 @@ static void __dw_hdmi_remove(struct dw_hdmi *hdmi)
 {
 	if (hdmi->audio && !IS_ERR(hdmi->audio))
 		platform_device_unregister(hdmi->audio);
+	if (!IS_ERR(hdmi->cec))
+		platform_device_unregister(hdmi->cec);
 
 	/* Disable all interrupts */
 	hdmi_writeb(hdmi, ~0, HDMI_IH_MUTE_PHY_STAT0);

drivers/gpu/drm/bridge/synopsys/dw-hdmi.h

@@ -555,6 +555,7 @@ enum {
 
 /* CONFIG0_ID field values */
 	HDMI_CONFIG0_I2S = 0x10,
+	HDMI_CONFIG0_CEC = 0x02,
 
 /* CONFIG1_ID field values */
 	HDMI_CONFIG1_AHB = 0x01,