media: platform: Add Amlogic Meson AO CEC Controller driver

The Amlogic SoC embeds a standalone CEC controller, this patch adds a driver
for such controller.
The controller does not need HPD to be active, and could support up to max
5 logical addresses, but only 1 is handled since the Suspend firmware can
make use of this unique logical address to wake up the device.

The Suspend firmware configuration will be added in an other patchset.
Signed-off-by: NNeil Armstrong <narmstrong@baylibre.com>
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
[hans.verkuil@cisco.com:s/if (ret)/if (res)/ to fix obvious typo]
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/platform/Kconfig

@@ -537,6 +537,17 @@ menuconfig CEC_PLATFORM_DRIVERS
 
 if CEC_PLATFORM_DRIVERS
 
+config VIDEO_MESON_AO_CEC
+	tristate "Amlogic Meson AO CEC driver"
+	depends on ARCH_MESON || COMPILE_TEST
+	select CEC_CORE
+	select CEC_NOTIFIER
+	---help---
+	  This is a driver for Amlogic Meson SoCs AO CEC interface. It uses the
+	  generic CEC framework interface.
+	  CEC bus is present in the HDMI connector and enables communication
+	  between compatible devices.
+
 config VIDEO_SAMSUNG_S5P_CEC
        tristate "Samsung S5P CEC driver"
        depends on PLAT_S5P || ARCH_EXYNOS || COMPILE_TEST

drivers/media/platform/Makefile

@@ -86,3 +86,5 @@ obj-$(CONFIG_VIDEO_MEDIATEK_MDP)	+= mtk-mdp/
 obj-$(CONFIG_VIDEO_MEDIATEK_JPEG)	+= mtk-jpeg/
 
 obj-$(CONFIG_VIDEO_QCOM_VENUS)		+= qcom/venus/
+
+obj-y					+= meson/

drivers/media/platform/meson/Makefile

+obj-$(CONFIG_VIDEO_MESON_AO_CEC)	+= ao-cec.o

drivers/media/platform/meson/ao-cec.c

+/*
+ * Driver for Amlogic Meson AO CEC Controller
+ *
+ * Copyright (C) 2015 Amlogic, Inc. All rights reserved
+ * Copyright (C) 2017 BayLibre, SAS
+ * Author: Neil Armstrong <narmstrong@baylibre.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+#include <linux/interrupt.h>
+#include <linux/reset.h>
+#include <media/cec.h>
+#include <media/cec-notifier.h>
+
+/* CEC Registers */
+
+/*
+ * [2:1] cntl_clk
+ *  - 0 = Disable clk (Power-off mode)
+ *  - 1 = Enable gated clock (Normal mode)
+ *  - 2 = Enable free-run clk (Debug mode)
+ */
+#define CEC_GEN_CNTL_REG		0x00
+
+#define CEC_GEN_CNTL_RESET		BIT(0)
+#define CEC_GEN_CNTL_CLK_DISABLE	0
+#define CEC_GEN_CNTL_CLK_ENABLE		1
+#define CEC_GEN_CNTL_CLK_ENABLE_DBG	2
+#define CEC_GEN_CNTL_CLK_CTRL_MASK	GENMASK(2, 1)
+
+/*
+ * [7:0] cec_reg_addr
+ * [15:8] cec_reg_wrdata
+ * [16] cec_reg_wr
+ *  - 0 = Read
+ *  - 1 = Write
+ * [23] bus free
+ * [31:24] cec_reg_rddata
+ */
+#define CEC_RW_REG			0x04
+
+#define CEC_RW_ADDR			GENMASK(7, 0)
+#define CEC_RW_WR_DATA			GENMASK(15, 8)
+#define CEC_RW_WRITE_EN			BIT(16)
+#define CEC_RW_BUS_BUSY			BIT(23)
+#define CEC_RW_RD_DATA			GENMASK(31, 24)
+
+/*
+ * [1] tx intr
+ * [2] rx intr
+ */
+#define CEC_INTR_MASKN_REG		0x08
+#define CEC_INTR_CLR_REG		0x0c
+#define CEC_INTR_STAT_REG		0x10
+
+#define CEC_INTR_TX			BIT(1)
+#define CEC_INTR_RX			BIT(2)
+
+/* CEC Commands */
+
+#define CEC_TX_MSG_0_HEADER		0x00
+#define CEC_TX_MSG_1_OPCODE		0x01
+#define CEC_TX_MSG_2_OP1		0x02
+#define CEC_TX_MSG_3_OP2		0x03
+#define CEC_TX_MSG_4_OP3		0x04
+#define CEC_TX_MSG_5_OP4		0x05
+#define CEC_TX_MSG_6_OP5		0x06
+#define CEC_TX_MSG_7_OP6		0x07
+#define CEC_TX_MSG_8_OP7		0x08
+#define CEC_TX_MSG_9_OP8		0x09
+#define CEC_TX_MSG_A_OP9		0x0A
+#define CEC_TX_MSG_B_OP10		0x0B
+#define CEC_TX_MSG_C_OP11		0x0C
+#define CEC_TX_MSG_D_OP12		0x0D
+#define CEC_TX_MSG_E_OP13		0x0E
+#define CEC_TX_MSG_F_OP14		0x0F
+#define CEC_TX_MSG_LENGTH		0x10
+#define CEC_TX_MSG_CMD			0x11
+#define CEC_TX_WRITE_BUF		0x12
+#define CEC_TX_CLEAR_BUF		0x13
+#define CEC_RX_MSG_CMD			0x14
+#define CEC_RX_CLEAR_BUF		0x15
+#define CEC_LOGICAL_ADDR0		0x16
+#define CEC_LOGICAL_ADDR1		0x17
+#define CEC_LOGICAL_ADDR2		0x18
+#define CEC_LOGICAL_ADDR3		0x19
+#define CEC_LOGICAL_ADDR4		0x1A
+#define CEC_CLOCK_DIV_H			0x1B
+#define CEC_CLOCK_DIV_L			0x1C
+#define CEC_QUIESCENT_25MS_BIT7_0	0x20
+#define CEC_QUIESCENT_25MS_BIT11_8	0x21
+#define CEC_STARTBITMINL2H_3MS5_BIT7_0	0x22
+#define CEC_STARTBITMINL2H_3MS5_BIT8	0x23
+#define CEC_STARTBITMAXL2H_3MS9_BIT7_0	0x24
+#define CEC_STARTBITMAXL2H_3MS9_BIT8	0x25
+#define CEC_STARTBITMINH_0MS6_BIT7_0	0x26
+#define CEC_STARTBITMINH_0MS6_BIT8	0x27
+#define CEC_STARTBITMAXH_1MS0_BIT7_0	0x28
+#define CEC_STARTBITMAXH_1MS0_BIT8	0x29
+#define CEC_STARTBITMINTOT_4MS3_BIT7_0	0x2A
+#define CEC_STARTBITMINTOT_4MS3_BIT9_8	0x2B
+#define CEC_STARTBITMAXTOT_4MS7_BIT7_0	0x2C
+#define CEC_STARTBITMAXTOT_4MS7_BIT9_8	0x2D
+#define CEC_LOGIC1MINL2H_0MS4_BIT7_0	0x2E
+#define CEC_LOGIC1MINL2H_0MS4_BIT8	0x2F
+#define CEC_LOGIC1MAXL2H_0MS8_BIT7_0	0x30
+#define CEC_LOGIC1MAXL2H_0MS8_BIT8	0x31
+#define CEC_LOGIC0MINL2H_1MS3_BIT7_0	0x32
+#define CEC_LOGIC0MINL2H_1MS3_BIT8	0x33
+#define CEC_LOGIC0MAXL2H_1MS7_BIT7_0	0x34
+#define CEC_LOGIC0MAXL2H_1MS7_BIT8	0x35
+#define CEC_LOGICMINTOTAL_2MS05_BIT7_0	0x36
+#define CEC_LOGICMINTOTAL_2MS05_BIT9_8	0x37
+#define CEC_LOGICMAXHIGH_2MS8_BIT7_0	0x38
+#define CEC_LOGICMAXHIGH_2MS8_BIT8	0x39
+#define CEC_LOGICERRLOW_3MS4_BIT7_0	0x3A
+#define CEC_LOGICERRLOW_3MS4_BIT8	0x3B
+#define CEC_NOMSMPPOINT_1MS05		0x3C
+#define CEC_DELCNTR_LOGICERR		0x3E
+#define CEC_TXTIME_17MS_BIT7_0		0x40
+#define CEC_TXTIME_17MS_BIT10_8		0x41
+#define CEC_TXTIME_2BIT_BIT7_0		0x42
+#define CEC_TXTIME_2BIT_BIT10_8		0x43
+#define CEC_TXTIME_4BIT_BIT7_0		0x44
+#define CEC_TXTIME_4BIT_BIT10_8		0x45
+#define CEC_STARTBITNOML2H_3MS7_BIT7_0	0x46
+#define CEC_STARTBITNOML2H_3MS7_BIT8	0x47
+#define CEC_STARTBITNOMH_0MS8_BIT7_0	0x48
+#define CEC_STARTBITNOMH_0MS8_BIT8	0x49
+#define CEC_LOGIC1NOML2H_0MS6_BIT7_0	0x4A
+#define CEC_LOGIC1NOML2H_0MS6_BIT8	0x4B
+#define CEC_LOGIC0NOML2H_1MS5_BIT7_0	0x4C
+#define CEC_LOGIC0NOML2H_1MS5_BIT8	0x4D
+#define CEC_LOGIC1NOMH_1MS8_BIT7_0	0x4E
+#define CEC_LOGIC1NOMH_1MS8_BIT8	0x4F
+#define CEC_LOGIC0NOMH_0MS9_BIT7_0	0x50
+#define CEC_LOGIC0NOMH_0MS9_BIT8	0x51
+#define CEC_LOGICERRLOW_3MS6_BIT7_0	0x52
+#define CEC_LOGICERRLOW_3MS6_BIT8	0x53
+#define CEC_CHKCONTENTION_0MS1		0x54
+#define CEC_PREPARENXTBIT_0MS05_BIT7_0	0x56
+#define CEC_PREPARENXTBIT_0MS05_BIT8	0x57
+#define CEC_NOMSMPACKPOINT_0MS45	0x58
+#define CEC_ACK0NOML2H_1MS5_BIT7_0	0x5A
+#define CEC_ACK0NOML2H_1MS5_BIT8	0x5B
+#define CEC_BUGFIX_DISABLE_0		0x60
+#define CEC_BUGFIX_DISABLE_1		0x61
+#define CEC_RX_MSG_0_HEADER		0x80
+#define CEC_RX_MSG_1_OPCODE		0x81
+#define CEC_RX_MSG_2_OP1		0x82
+#define CEC_RX_MSG_3_OP2		0x83
+#define CEC_RX_MSG_4_OP3		0x84
+#define CEC_RX_MSG_5_OP4		0x85
+#define CEC_RX_MSG_6_OP5		0x86
+#define CEC_RX_MSG_7_OP6		0x87
+#define CEC_RX_MSG_8_OP7		0x88
+#define CEC_RX_MSG_9_OP8		0x89
+#define CEC_RX_MSG_A_OP9		0x8A
+#define CEC_RX_MSG_B_OP10		0x8B
+#define CEC_RX_MSG_C_OP11		0x8C
+#define CEC_RX_MSG_D_OP12		0x8D
+#define CEC_RX_MSG_E_OP13		0x8E
+#define CEC_RX_MSG_F_OP14		0x8F
+#define CEC_RX_MSG_LENGTH		0x90
+#define CEC_RX_MSG_STATUS		0x91
+#define CEC_RX_NUM_MSG			0x92
+#define CEC_TX_MSG_STATUS		0x93
+#define CEC_TX_NUM_MSG			0x94
+
+
+/* CEC_TX_MSG_CMD definition */
+#define TX_NO_OP	0  /* No transaction */
+#define TX_REQ_CURRENT	1  /* Transmit earliest message in buffer */
+#define TX_ABORT	2  /* Abort transmitting earliest message */
+#define TX_REQ_NEXT	3  /* Overwrite earliest msg, transmit next */
+
+/* tx_msg_status definition */
+#define TX_IDLE		0  /* No transaction */
+#define TX_BUSY		1  /* Transmitter is busy */
+#define TX_DONE		2  /* Message successfully transmitted */
+#define TX_ERROR	3  /* Message transmitted with error */
+
+/* rx_msg_cmd */
+#define RX_NO_OP	0  /* No transaction */
+#define RX_ACK_CURRENT	1  /* Read earliest message in buffer */
+#define RX_DISABLE	2  /* Disable receiving latest message */
+#define RX_ACK_NEXT	3  /* Clear earliest msg, read next */
+
+/* rx_msg_status */
+#define RX_IDLE		0  /* No transaction */
+#define RX_BUSY		1  /* Receiver is busy */
+#define RX_DONE		2  /* Message has been received successfully */
+#define RX_ERROR	3  /* Message has been received with error */
+
+/* RX_CLEAR_BUF options */
+#define CLEAR_START	1
+#define CLEAR_STOP	0
+
+/* CEC_LOGICAL_ADDRx options */
+#define LOGICAL_ADDR_MASK	0xf
+#define LOGICAL_ADDR_VALID	BIT(4)
+#define LOGICAL_ADDR_DISABLE	0
+
+#define CEC_CLK_RATE		32768
+
+struct meson_ao_cec_device {
+	struct platform_device		*pdev;
+	void __iomem			*base;
+	struct clk			*core;
+	spinlock_t			cec_reg_lock;
+	struct cec_notifier		*notify;
+	struct cec_adapter		*adap;
+	struct cec_msg			rx_msg;
+};
+
+#define writel_bits_relaxed(mask, val, addr) \
+	writel_relaxed((readl_relaxed(addr) & ~(mask)) | (val), addr)
+
+static inline int meson_ao_cec_wait_busy(struct meson_ao_cec_device *ao_cec)
+{
+	ktime_t timeout = ktime_add_us(ktime_get(), 5000);
+
+	while (readl_relaxed(ao_cec->base + CEC_RW_REG) & CEC_RW_BUS_BUSY) {
+		if (ktime_compare(ktime_get(), timeout) > 0)
+			return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+static void meson_ao_cec_read(struct meson_ao_cec_device *ao_cec,
+			     unsigned long address, u8 *data,
+			     int *res)
+{
+	unsigned long flags;
+	u32 reg = FIELD_PREP(CEC_RW_ADDR, address);
+	int ret = 0;
+
+	if (res && *res)
+		return;
+
+	spin_lock_irqsave(&ao_cec->cec_reg_lock, flags);
+
+	ret = meson_ao_cec_wait_busy(ao_cec);
+	if (ret)
+		goto read_out;
+
+	writel_relaxed(reg, ao_cec->base + CEC_RW_REG);
+
+	ret = meson_ao_cec_wait_busy(ao_cec);
+	if (ret)
+		goto read_out;
+
+	*data = FIELD_GET(CEC_RW_RD_DATA,
+			  readl_relaxed(ao_cec->base + CEC_RW_REG));
+
+read_out:
+	spin_unlock_irqrestore(&ao_cec->cec_reg_lock, flags);
+
+	if (res)
+		*res = ret;
+}
+
+static void meson_ao_cec_write(struct meson_ao_cec_device *ao_cec,
+			       unsigned long address, u8 data,
+			       int *res)
+{
+	unsigned long flags;
+	u32 reg = FIELD_PREP(CEC_RW_ADDR, address) |
+		  FIELD_PREP(CEC_RW_WR_DATA, data) |
+		  CEC_RW_WRITE_EN;
+	int ret = 0;
+
+	if (res && *res)
+		return;
+
+	spin_lock_irqsave(&ao_cec->cec_reg_lock, flags);
+
+	ret = meson_ao_cec_wait_busy(ao_cec);
+	if (ret)
+		goto write_out;
+
+	writel_relaxed(reg, ao_cec->base + CEC_RW_REG);
+
+write_out:
+	spin_unlock_irqrestore(&ao_cec->cec_reg_lock, flags);
+
+	if (res)
+		*res = ret;
+}
+
+static inline void meson_ao_cec_irq_setup(struct meson_ao_cec_device *ao_cec,
+				      bool enable)
+{
+	u32 cfg = CEC_INTR_TX | CEC_INTR_RX;
+
+	writel_bits_relaxed(cfg, enable ? cfg : 0,
+			    ao_cec->base + CEC_INTR_MASKN_REG);
+}
+
+static inline int meson_ao_cec_clear(struct meson_ao_cec_device *ao_cec)
+{
+	int ret = 0;
+
+	meson_ao_cec_write(ao_cec, CEC_RX_MSG_CMD, RX_DISABLE, &ret);
+	meson_ao_cec_write(ao_cec, CEC_TX_MSG_CMD, TX_ABORT, &ret);
+	meson_ao_cec_write(ao_cec, CEC_RX_CLEAR_BUF, 1, &ret);
+	meson_ao_cec_write(ao_cec, CEC_TX_CLEAR_BUF, 1, &ret);
+	if (ret)
+		return ret;
+
+	udelay(100);
+
+	meson_ao_cec_write(ao_cec, CEC_RX_CLEAR_BUF, 0, &ret);
+	meson_ao_cec_write(ao_cec, CEC_TX_CLEAR_BUF, 0, &ret);
+	if (ret)
+		return ret;
+
+	udelay(100);
+
+	meson_ao_cec_write(ao_cec, CEC_RX_MSG_CMD, RX_NO_OP, &ret);
+	meson_ao_cec_write(ao_cec, CEC_TX_MSG_CMD, TX_NO_OP, &ret);
+
+	return ret;
+}
+
+static int meson_ao_cec_arbit_bit_time_set(struct meson_ao_cec_device *ao_cec,
+					   unsigned int bit_set,
+					   unsigned int time_set)
+{
+	int ret = 0;
+
+	switch (bit_set) {
+	case CEC_SIGNAL_FREE_TIME_RETRY:
+		meson_ao_cec_write(ao_cec, CEC_TXTIME_4BIT_BIT7_0,
+				   time_set & 0xff, &ret);
+		meson_ao_cec_write(ao_cec, CEC_TXTIME_4BIT_BIT10_8,
+				   (time_set >> 8) & 0x7, &ret);
+		break;
+
+	case CEC_SIGNAL_FREE_TIME_NEW_INITIATOR:
+		meson_ao_cec_write(ao_cec, CEC_TXTIME_2BIT_BIT7_0,
+				   time_set & 0xff, &ret);
+		meson_ao_cec_write(ao_cec, CEC_TXTIME_2BIT_BIT10_8,
+				   (time_set >> 8) & 0x7, &ret);
+		break;
+
+	case CEC_SIGNAL_FREE_TIME_NEXT_XFER:
+		meson_ao_cec_write(ao_cec, CEC_TXTIME_17MS_BIT7_0,
+				   time_set & 0xff, &ret);
+		meson_ao_cec_write(ao_cec, CEC_TXTIME_17MS_BIT10_8,
+				   (time_set >> 8) & 0x7, &ret);
+		break;
+	}
+
+	return ret;
+}
+
+static irqreturn_t meson_ao_cec_irq(int irq, void *data)
+{
+	struct meson_ao_cec_device *ao_cec = data;
+	u32 stat = readl_relaxed(ao_cec->base + CEC_INTR_STAT_REG);
+
+	if (stat)
+		return IRQ_WAKE_THREAD;
+
+	return IRQ_NONE;
+}
+
+static void meson_ao_cec_irq_tx(struct meson_ao_cec_device *ao_cec)
+{
+	unsigned long tx_status = 0;
+	u8 stat;
+	int ret = 0;
+
+	meson_ao_cec_read(ao_cec, CEC_TX_MSG_STATUS, &stat, &ret);
+	if (ret)
+		goto tx_reg_err;
+
+	switch (stat) {
+	case TX_DONE:
+		tx_status = CEC_TX_STATUS_OK;
+		break;
+
+	case TX_BUSY:
+		tx_status = CEC_TX_STATUS_ARB_LOST;
+		break;
+
+	case TX_IDLE:
+		tx_status = CEC_TX_STATUS_LOW_DRIVE;
+		break;
+
+	case TX_ERROR:
+	default:
+		tx_status = CEC_TX_STATUS_NACK;
+		break;
+	}
+
+	/* Clear Interruption */
+	writel_relaxed(CEC_INTR_TX, ao_cec->base + CEC_INTR_CLR_REG);
+
+	/* Stop TX */
+	meson_ao_cec_write(ao_cec, CEC_TX_MSG_CMD, TX_NO_OP, &ret);
+	if (ret)
+		goto tx_reg_err;
+
+	cec_transmit_attempt_done(ao_cec->adap, tx_status);
+	return;
+
+tx_reg_err:
+	cec_transmit_attempt_done(ao_cec->adap, CEC_TX_STATUS_ERROR);
+}
+
+static void meson_ao_cec_irq_rx(struct meson_ao_cec_device *ao_cec)
+{
+	int i, ret = 0;
+	u8 reg;
+
+	meson_ao_cec_read(ao_cec, CEC_RX_MSG_STATUS, &reg, &ret);
+	if (reg != RX_DONE)
+		goto rx_out;
+
+	meson_ao_cec_read(ao_cec, CEC_RX_NUM_MSG, &reg, &ret);
+	if (reg != 1)
+		goto rx_out;
+
+	meson_ao_cec_read(ao_cec, CEC_RX_MSG_LENGTH, &reg, &ret);
+
+	ao_cec->rx_msg.len = reg + 1;
+	if (ao_cec->rx_msg.len > CEC_MAX_MSG_SIZE)
+		ao_cec->rx_msg.len = CEC_MAX_MSG_SIZE;
+
+	for (i = 0; i < ao_cec->rx_msg.len; i++) {
+		u8 byte;
+
+		meson_ao_cec_read(ao_cec, CEC_RX_MSG_0_HEADER + i, &byte, &ret);
+
+		ao_cec->rx_msg.msg[i] = byte;
+	}
+
+	if (ret)
+		goto rx_out;
+
+	cec_received_msg(ao_cec->adap, &ao_cec->rx_msg);
+
+rx_out:
+	/* Clear Interruption */
+	writel_relaxed(CEC_INTR_RX, ao_cec->base + CEC_INTR_CLR_REG);
+
+	/* Ack RX message */
+	meson_ao_cec_write(ao_cec, CEC_RX_MSG_CMD, RX_ACK_CURRENT, &ret);
+	meson_ao_cec_write(ao_cec, CEC_RX_MSG_CMD, RX_NO_OP, &ret);
+
+	/* Clear RX buffer */
+	meson_ao_cec_write(ao_cec, CEC_RX_CLEAR_BUF, CLEAR_START, &ret);
+	meson_ao_cec_write(ao_cec, CEC_RX_CLEAR_BUF, CLEAR_STOP, &ret);
+}
+
+static irqreturn_t meson_ao_cec_irq_thread(int irq, void *data)
+{
+	struct meson_ao_cec_device *ao_cec = data;
+	u32 stat = readl_relaxed(ao_cec->base + CEC_INTR_STAT_REG);
+
+	if (stat & CEC_INTR_TX)
+		meson_ao_cec_irq_tx(ao_cec);
+
+	meson_ao_cec_irq_rx(ao_cec);
+
+	return IRQ_HANDLED;
+}
+
+static int meson_ao_cec_set_log_addr(struct cec_adapter *adap, u8 logical_addr)
+{
+	struct meson_ao_cec_device *ao_cec = adap->priv;
+	int ret = 0;
+
+	meson_ao_cec_write(ao_cec, CEC_LOGICAL_ADDR0,
+			   LOGICAL_ADDR_DISABLE, &ret);
+	if (ret)
+		return ret;
+
+	ret = meson_ao_cec_clear(ao_cec);
+	if (ret)
+		return ret;
+
+	if (logical_addr == CEC_LOG_ADDR_INVALID)
+		return 0;
+
+	meson_ao_cec_write(ao_cec, CEC_LOGICAL_ADDR0,
+			   logical_addr & LOGICAL_ADDR_MASK, &ret);
+	if (ret)
+		return ret;
+
+	udelay(100);
+
+	meson_ao_cec_write(ao_cec, CEC_LOGICAL_ADDR0,
+			   (logical_addr & LOGICAL_ADDR_MASK) |
+			   LOGICAL_ADDR_VALID, &ret);
+
+	return ret;
+}
+
+static int meson_ao_cec_transmit(struct cec_adapter *adap, u8 attempts,
+				 u32 signal_free_time, struct cec_msg *msg)
+{
+	struct meson_ao_cec_device *ao_cec = adap->priv;
+	int i, ret = 0;
+	u8 reg;
+
+	meson_ao_cec_read(ao_cec, CEC_TX_MSG_STATUS, &reg, &ret);
+	if (ret)
+		return ret;
+
+	if (reg == TX_BUSY) {
+		dev_err(&ao_cec->pdev->dev, "%s: busy TX: aborting\n",
+			__func__);
+		meson_ao_cec_write(ao_cec, CEC_TX_MSG_CMD, TX_ABORT, &ret);
+	}
+
+	for (i = 0; i < msg->len; i++) {
+		meson_ao_cec_write(ao_cec, CEC_TX_MSG_0_HEADER + i,
+				   msg->msg[i], &ret);
+	}
+
+	meson_ao_cec_write(ao_cec, CEC_TX_MSG_LENGTH, msg->len - 1, &ret);
+	meson_ao_cec_write(ao_cec, CEC_TX_MSG_CMD, TX_REQ_CURRENT, &ret);
+
+	return ret;
+}
+
+static int meson_ao_cec_adap_enable(struct cec_adapter *adap, bool enable)
+{
+	struct meson_ao_cec_device *ao_cec = adap->priv;
+	int ret;
+
+	meson_ao_cec_irq_setup(ao_cec, false);
+
+	writel_bits_relaxed(CEC_GEN_CNTL_RESET, CEC_GEN_CNTL_RESET,
+			    ao_cec->base + CEC_GEN_CNTL_REG);
+
+	if (!enable)
+		return 0;
+
+	/* Enable gated clock (Normal mode). */
+	writel_bits_relaxed(CEC_GEN_CNTL_CLK_CTRL_MASK,
+			    FIELD_PREP(CEC_GEN_CNTL_CLK_CTRL_MASK,
+				       CEC_GEN_CNTL_CLK_ENABLE),
+			    ao_cec->base + CEC_GEN_CNTL_REG);
+
+	udelay(100);
+
+	/* Release Reset */
+	writel_bits_relaxed(CEC_GEN_CNTL_RESET, 0,
+			    ao_cec->base + CEC_GEN_CNTL_REG);
+
+	/* Clear buffers */
+	ret = meson_ao_cec_clear(ao_cec);
+	if (ret)
+		return ret;
+
+	/* CEC arbitration 3/5/7 bit time set. */
+	ret = meson_ao_cec_arbit_bit_time_set(ao_cec,
+					CEC_SIGNAL_FREE_TIME_RETRY,
+					0x118);
+	if (ret)
+		return ret;
+	ret = meson_ao_cec_arbit_bit_time_set(ao_cec,
+					CEC_SIGNAL_FREE_TIME_NEW_INITIATOR,
+					0x000);
+	if (ret)
+		return ret;
+	ret = meson_ao_cec_arbit_bit_time_set(ao_cec,
+					CEC_SIGNAL_FREE_TIME_NEXT_XFER,
+					0x2aa);
+	if (ret)
+		return ret;
+
+	meson_ao_cec_irq_setup(ao_cec, true);
+
+	return 0;
+}
+
+static const struct cec_adap_ops meson_ao_cec_ops = {
+	.adap_enable = meson_ao_cec_adap_enable,
+	.adap_log_addr = meson_ao_cec_set_log_addr,
+	.adap_transmit = meson_ao_cec_transmit,
+};
+
+static int meson_ao_cec_probe(struct platform_device *pdev)
+{
+	struct meson_ao_cec_device *ao_cec;
+	struct platform_device *hdmi_dev;
+	struct device_node *np;
+	struct resource *res;
+	int ret, irq;
+
+	np = of_parse_phandle(pdev->dev.of_node, "hdmi-phandle", 0);
+	if (!np) {
+		dev_err(&pdev->dev, "Failed to find hdmi node\n");
+		return -ENODEV;
+	}
+
+	hdmi_dev = of_find_device_by_node(np);
+	if (hdmi_dev == NULL)
+		return -EPROBE_DEFER;
+
+	ao_cec = devm_kzalloc(&pdev->dev, sizeof(*ao_cec), GFP_KERNEL);
+	if (!ao_cec)
+		return -ENOMEM;
+
+	spin_lock_init(&ao_cec->cec_reg_lock);
+
+	ao_cec->notify = cec_notifier_get(&hdmi_dev->dev);
+	if (!ao_cec->notify)
+		return -ENOMEM;
+
+	ao_cec->adap = cec_allocate_adapter(&meson_ao_cec_ops, ao_cec,
+					    "meson_ao_cec",
+					    CEC_CAP_LOG_ADDRS |
+					    CEC_CAP_TRANSMIT |
+					    CEC_CAP_RC |
+					    CEC_CAP_PASSTHROUGH,
+					    1); /* Use 1 for now */
+	if (IS_ERR(ao_cec->adap)) {
+		ret = PTR_ERR(ao_cec->adap);
+		goto out_probe_notify;
+	}
+
+	ao_cec->adap->owner = THIS_MODULE;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	ao_cec->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(ao_cec->base)) {
+		ret = PTR_ERR(ao_cec->base);
+		goto out_probe_adapter;
+	}
+
+	irq = platform_get_irq(pdev, 0);
+	ret = devm_request_threaded_irq(&pdev->dev, irq,
+					meson_ao_cec_irq,
+					meson_ao_cec_irq_thread,
+					0, NULL, ao_cec);
+	if (ret) {
+		dev_err(&pdev->dev, "irq request failed\n");
+		goto out_probe_adapter;
+	}
+
+	ao_cec->core = devm_clk_get(&pdev->dev, "core");
+	if (IS_ERR(ao_cec->core)) {
+		dev_err(&pdev->dev, "core clock request failed\n");
+		ret = PTR_ERR(ao_cec->core);
+		goto out_probe_adapter;
+	}
+
+	ret = clk_prepare_enable(ao_cec->core);
+	if (ret) {
+		dev_err(&pdev->dev, "core clock enable failed\n");
+		goto out_probe_adapter;
+	}
+
+	ret = clk_set_rate(ao_cec->core, CEC_CLK_RATE);
+	if (ret) {
+		dev_err(&pdev->dev, "core clock set rate failed\n");
+		goto out_probe_clk;
+	}
+
+	device_reset_optional(&pdev->dev);
+
+	ao_cec->pdev = pdev;
+	platform_set_drvdata(pdev, ao_cec);
+
+	ret = cec_register_adapter(ao_cec->adap, &pdev->dev);
+	if (ret < 0) {
+		cec_notifier_put(ao_cec->notify);
+		goto out_probe_clk;
+	}
+
+	/* Setup Hardware */
+	writel_relaxed(CEC_GEN_CNTL_RESET,
+		       ao_cec->base + CEC_GEN_CNTL_REG);
+
+	cec_register_cec_notifier(ao_cec->adap, ao_cec->notify);
+
+	return 0;
+
+out_probe_clk:
+	clk_disable_unprepare(ao_cec->core);
+
+out_probe_adapter:
+	cec_delete_adapter(ao_cec->adap);
+
+out_probe_notify:
+	cec_notifier_put(ao_cec->notify);
+
+	dev_err(&pdev->dev, "CEC controller registration failed\n");
+
+	return ret;
+}
+
+static int meson_ao_cec_remove(struct platform_device *pdev)
+{
+	struct meson_ao_cec_device *ao_cec = platform_get_drvdata(pdev);
+
+	clk_disable_unprepare(ao_cec->core);
+
+	cec_unregister_adapter(ao_cec->adap);
+
+	cec_notifier_put(ao_cec->notify);
+
+	return 0;
+}
+
+static const struct of_device_id meson_ao_cec_of_match[] = {
+	{ .compatible = "amlogic,meson-gx-ao-cec", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, meson_ao_cec_of_match);
+
+static struct platform_driver meson_ao_cec_driver = {
+	.probe   = meson_ao_cec_probe,
+	.remove  = meson_ao_cec_remove,
+	.driver  = {
+		.name = "meson-ao-cec",
+		.of_match_table = of_match_ptr(meson_ao_cec_of_match),
+	},
+};
+
+module_platform_driver(meson_ao_cec_driver);
+
+MODULE_DESCRIPTION("Meson AO CEC Controller driver");
+MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
+MODULE_LICENSE("GPL");