drm/i2c: tda9950: add CEC driver

Add a CEC driver for the TDA9950, which is a stand-alone I2C CEC device,
but is also integrated into HDMI transceivers such as the TDA9989 and
TDA19989.

The TDA9950 contains a command processor which handles retransmissions
and the low level bus protocol. The driver just has to read and write
the messages, and handle error conditions.

Reviewed-by: Hans Verkuil <[e-mail]>
Signed-off-by: Russell King <[e-mail]>

drivers/gpu/drm/i2c/Kconfig

···
 	help
 	  Support for NXP Semiconductors TDA998X HDMI encoders.
 
+config DRM_I2C_NXP_TDA9950
+	tristate "NXP Semiconductors TDA9950/TDA998X HDMI CEC"
+	select CEC_NOTIFIER
+	select CEC_CORE
+
 endmenu

drivers/gpu/drm/i2c/Makefile

···
 
 tda998x-y := tda998x_drv.o
 obj-$(CONFIG_DRM_I2C_NXP_TDA998X) += tda998x.o
+obj-$(CONFIG_DRM_I2C_NXP_TDA9950) += tda9950.o

drivers/gpu/drm/i2c/tda9950.c

···
+/*
+ *  TDA9950 Consumer Electronics Control driver
+ *
+ * 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.
+ *
+ * The NXP TDA9950 implements the HDMI Consumer Electronics Control
+ * interface.  The host interface is similar to a mailbox: the data
+ * registers starting at REG_CDR0 are written to send a command to the
+ * internal CPU, and replies are read from these registers.
+ *
+ * As the data registers represent a mailbox, they must be accessed
+ * as a single I2C transaction.  See the TDA9950 data sheet for details.
+ */
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/platform_data/tda9950.h>
+#include <linux/slab.h>
+#include <drm/drm_edid.h>
+#include <media/cec.h>
+#include <media/cec-notifier.h>
+
+enum {
+	REG_CSR = 0x00,
+	CSR_BUSY = BIT(7),
+	CSR_INT  = BIT(6),
+	CSR_ERR  = BIT(5),
+
+	REG_CER = 0x01,
+
+	REG_CVR = 0x02,
+
+	REG_CCR = 0x03,
+	CCR_RESET = BIT(7),
+	CCR_ON    = BIT(6),
+
+	REG_ACKH = 0x04,
+	REG_ACKL = 0x05,
+
+	REG_CCONR = 0x06,
+	CCONR_ENABLE_ERROR = BIT(4),
+	CCONR_RETRY_MASK = 7,
+
+	REG_CDR0 = 0x07,
+
+	CDR1_REQ = 0x00,
+	CDR1_CNF = 0x01,
+	CDR1_IND = 0x81,
+	CDR1_ERR = 0x82,
+	CDR1_IER = 0x83,
+
+	CDR2_CNF_SUCCESS    = 0x00,
+	CDR2_CNF_OFF_STATE  = 0x80,
+	CDR2_CNF_BAD_REQ    = 0x81,
+	CDR2_CNF_CEC_ACCESS = 0x82,
+	CDR2_CNF_ARB_ERROR  = 0x83,
+	CDR2_CNF_BAD_TIMING = 0x84,
+	CDR2_CNF_NACK_ADDR  = 0x85,
+	CDR2_CNF_NACK_DATA  = 0x86,
+};
+
+struct tda9950_priv {
+	struct i2c_client *client;
+	struct device *hdmi;
+	struct cec_adapter *adap;
+	struct tda9950_glue *glue;
+	u16 addresses;
+	struct cec_msg rx_msg;
+	struct cec_notifier *notify;
+	bool open;
+};
+
+static int tda9950_write_range(struct i2c_client *client, u8 addr, u8 *p, int cnt)
+{
+	struct i2c_msg msg;
+	u8 buf[cnt + 1];
+	int ret;
+
+	buf[0] = addr;
+	memcpy(buf + 1, p, cnt);
+
+	msg.addr = client->addr;
+	msg.flags = 0;
+	msg.len = cnt + 1;
+	msg.buf = buf;
+
+	dev_dbg(&client->dev, "wr 0x%02x: %*ph\n", addr, cnt, p);
+
+	ret = i2c_transfer(client->adapter, &msg, 1);
+	if (ret < 0)
+		dev_err(&client->dev, "Error %d writing to cec:0x%x\n", ret, addr);
+	return ret < 0 ? ret : 0;
+}
+
+static void tda9950_write(struct i2c_client *client, u8 addr, u8 val)
+{
+	tda9950_write_range(client, addr, &val, 1);
+}
+
+static int tda9950_read_range(struct i2c_client *client, u8 addr, u8 *p, int cnt)
+{
+	struct i2c_msg msg[2];
+	int ret;
+
+	msg[0].addr = client->addr;
+	msg[0].flags = 0;
+	msg[0].len = 1;
+	msg[0].buf = &addr;
+	msg[1].addr = client->addr;
+	msg[1].flags = I2C_M_RD;
+	msg[1].len = cnt;
+	msg[1].buf = p;
+
+	ret = i2c_transfer(client->adapter, msg, 2);
+	if (ret < 0)
+		dev_err(&client->dev, "Error %d reading from cec:0x%x\n", ret, addr);
+
+	dev_dbg(&client->dev, "rd 0x%02x: %*ph\n", addr, cnt, p);
+
+	return ret;
+}
+
+static u8 tda9950_read(struct i2c_client *client, u8 addr)
+{
+	int ret;
+	u8 val;
+
+	ret = tda9950_read_range(client, addr, &val, 1);
+	if (ret < 0)
+		val = 0;
+
+	return val;
+}
+
+static irqreturn_t tda9950_irq(int irq, void *data)
+{
+	struct tda9950_priv *priv = data;
+	unsigned int tx_status;
+	u8 csr, cconr, buf[19];
+	u8 arb_lost_cnt, nack_cnt, err_cnt;
+
+	if (!priv->open)
+		return IRQ_NONE;
+
+	csr = tda9950_read(priv->client, REG_CSR);
+	if (!(csr & CSR_INT))
+		return IRQ_NONE;
+
+	cconr = tda9950_read(priv->client, REG_CCONR) & CCONR_RETRY_MASK;
+
+	tda9950_read_range(priv->client, REG_CDR0, buf, sizeof(buf));
+
+	/*
+	 * This should never happen: the data sheet says that there will
+	 * always be a valid message if the interrupt line is asserted.
+	 */
+	if (buf[0] == 0) {
+		dev_warn(&priv->client->dev, "interrupt pending, but no message?\n");
+		return IRQ_NONE;
+	}
+
+	switch (buf[1]) {
+	case CDR1_CNF: /* transmit result */
+		arb_lost_cnt = nack_cnt = err_cnt = 0;
+		switch (buf[2]) {
+		case CDR2_CNF_SUCCESS:
+			tx_status = CEC_TX_STATUS_OK;
+			break;
+
+		case CDR2_CNF_ARB_ERROR:
+			tx_status = CEC_TX_STATUS_ARB_LOST;
+			arb_lost_cnt = cconr;
+			break;
+
+		case CDR2_CNF_NACK_ADDR:
+			tx_status = CEC_TX_STATUS_NACK;
+			nack_cnt = cconr;
+			break;
+
+		default: /* some other error, refer to TDA9950 docs */
+			dev_err(&priv->client->dev, "CNF reply error 0x%02x\n",
+				buf[2]);
+			tx_status = CEC_TX_STATUS_ERROR;
+			err_cnt = cconr;
+			break;
+		}
+		/* TDA9950 executes all retries for us */
+		tx_status |= CEC_TX_STATUS_MAX_RETRIES;
+		cec_transmit_done(priv->adap, tx_status, arb_lost_cnt,
+				  nack_cnt, 0, err_cnt);
+		break;
+
+	case CDR1_IND:
+		priv->rx_msg.len = buf[0] - 2;
+		if (priv->rx_msg.len > CEC_MAX_MSG_SIZE)
+			priv->rx_msg.len = CEC_MAX_MSG_SIZE;
+
+		memcpy(priv->rx_msg.msg, buf + 2, priv->rx_msg.len);
+		cec_received_msg(priv->adap, &priv->rx_msg);
+		break;
+
+	default: /* unknown */
+		dev_err(&priv->client->dev, "unknown service id 0x%02x\n",
+			buf[1]);
+		break;
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int tda9950_cec_transmit(struct cec_adapter *adap, u8 attempts,
+				u32 signal_free_time, struct cec_msg *msg)
+{
+	struct tda9950_priv *priv = adap->priv;
+	u8 buf[CEC_MAX_MSG_SIZE + 2];
+
+	buf[0] = 2 + msg->len;
+	buf[1] = CDR1_REQ;
+	memcpy(buf + 2, msg->msg, msg->len);
+
+	if (attempts > 5)
+		attempts = 5;
+
+	tda9950_write(priv->client, REG_CCONR, attempts);
+
+	return tda9950_write_range(priv->client, REG_CDR0, buf, 2 + msg->len);
+}
+
+static int tda9950_cec_adap_log_addr(struct cec_adapter *adap, u8 addr)
+{
+	struct tda9950_priv *priv = adap->priv;
+	u16 addresses;
+	u8 buf[2];
+
+	if (addr == CEC_LOG_ADDR_INVALID)
+		addresses = priv->addresses = 0;
+	else
+		addresses = priv->addresses |= BIT(addr);
+
+	/* TDA9950 doesn't want address 15 set */
+	addresses &= 0x7fff;
+	buf[0] = addresses >> 8;
+	buf[1] = addresses;
+
+	return tda9950_write_range(priv->client, REG_ACKH, buf, 2);
+}
+
+/*
+ * When operating as part of the TDA998x, we need additional handling
+ * to initialise and shut down the TDA9950 part of the device.  These
+ * two hooks are provided to allow the TDA998x code to perform those
+ * activities.
+ */
+static int tda9950_glue_open(struct tda9950_priv *priv)
+{
+	int ret = 0;
+
+	if (priv->glue && priv->glue->open)
+		ret = priv->glue->open(priv->glue->data);
+
+	priv->open = true;
+
+	return ret;
+}
+
+static void tda9950_glue_release(struct tda9950_priv *priv)
+{
+	priv->open = false;
+
+	if (priv->glue && priv->glue->release)
+		priv->glue->release(priv->glue->data);
+}
+
+static int tda9950_open(struct tda9950_priv *priv)
+{
+	struct i2c_client *client = priv->client;
+	int ret;
+
+	ret = tda9950_glue_open(priv);
+	if (ret)
+		return ret;
+
+	/* Reset the TDA9950, and wait 250ms for it to recover */
+	tda9950_write(client, REG_CCR, CCR_RESET);
+	msleep(250);
+
+	tda9950_cec_adap_log_addr(priv->adap, CEC_LOG_ADDR_INVALID);
+
+	/* Start the command processor */
+	tda9950_write(client, REG_CCR, CCR_ON);
+
+	return 0;
+}
+
+static void tda9950_release(struct tda9950_priv *priv)
+{
+	struct i2c_client *client = priv->client;
+	int timeout = 50;
+	u8 csr;
+
+	/* Stop the command processor */
+	tda9950_write(client, REG_CCR, 0);
+
+	/* Wait up to .5s for it to signal non-busy */
+	do {
+		csr = tda9950_read(client, REG_CSR);
+		if (!(csr & CSR_BUSY) || --timeout)
+			break;
+		msleep(10);
+	} while (1);
+
+	/* Warn the user that their IRQ may die if it's shared. */
+	if (csr & CSR_BUSY)
+		dev_warn(&client->dev, "command processor failed to stop, irq%d may die (csr=0x%02x)\n",
+			 client->irq, csr);
+
+	tda9950_glue_release(priv);
+}
+
+static int tda9950_cec_adap_enable(struct cec_adapter *adap, bool enable)
+{
+	struct tda9950_priv *priv = adap->priv;
+
+	if (!enable) {
+		tda9950_release(priv);
+		return 0;
+	} else {
+		return tda9950_open(priv);
+	}
+}
+
+static const struct cec_adap_ops tda9950_cec_ops = {
+	.adap_enable = tda9950_cec_adap_enable,
+	.adap_log_addr = tda9950_cec_adap_log_addr,
+	.adap_transmit = tda9950_cec_transmit,
+};
+
+/*
+ * When operating as part of the TDA998x, we need to claim additional
+ * resources.  These two hooks permit the management of those resources.
+ */
+static void tda9950_devm_glue_exit(void *data)
+{
+	struct tda9950_glue *glue = data;
+
+	if (glue && glue->exit)
+		glue->exit(glue->data);
+}
+
+static int tda9950_devm_glue_init(struct device *dev, struct tda9950_glue *glue)
+{
+	int ret;
+
+	if (glue && glue->init) {
+		ret = glue->init(glue->data);
+		if (ret)
+			return ret;
+	}
+
+	ret = devm_add_action(dev, tda9950_devm_glue_exit, glue);
+	if (ret)
+		tda9950_devm_glue_exit(glue);
+
+	return ret;
+}
+
+static void tda9950_cec_del(void *data)
+{
+	struct tda9950_priv *priv = data;
+
+	cec_delete_adapter(priv->adap);
+}
+
+static int tda9950_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct tda9950_glue *glue = client->dev.platform_data;
+	struct device *dev = &client->dev;
+	struct tda9950_priv *priv;
+	unsigned long irqflags;
+	int ret;
+	u8 cvr;
+
+	/*
+	 * We must have I2C functionality: our multi-byte accesses
+	 * must be performed as a single contiguous transaction.
+	 */
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
+		dev_err(&client->dev,
+			"adapter does not support I2C functionality\n");
+		return -ENXIO;
+	}
+
+	/* We must have an interrupt to be functional. */
+	if (client->irq <= 0) {
+		dev_err(&client->dev, "driver requires an interrupt\n");
+		return -ENXIO;
+	}
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->client = client;
+	priv->glue = glue;
+
+	i2c_set_clientdata(client, priv);
+
+	/*
+	 * If we're part of a TDA998x, we want the class devices to be
+	 * associated with the HDMI Tx so we have a tight relationship
+	 * between the HDMI interface and the CEC interface.
+	 */
+	priv->hdmi = dev;
+	if (glue && glue->parent)
+		priv->hdmi = glue->parent;
+
+	priv->adap = cec_allocate_adapter(&tda9950_cec_ops, priv, "tda9950",
+					  CEC_CAP_DEFAULTS,
+					  CEC_MAX_LOG_ADDRS);
+	if (IS_ERR(priv->adap))
+		return PTR_ERR(priv->adap);
+
+	ret = devm_add_action(dev, tda9950_cec_del, priv);
+	if (ret) {
+		cec_delete_adapter(priv->adap);
+		return ret;
+	}
+
+	ret = tda9950_devm_glue_init(dev, glue);
+	if (ret)
+		return ret;
+
+	ret = tda9950_glue_open(priv);
+	if (ret)
+		return ret;
+
+	cvr = tda9950_read(client, REG_CVR);
+
+	dev_info(&client->dev,
+		 "TDA9950 CEC interface, hardware version %u.%u\n",
+		 cvr >> 4, cvr & 15);
+
+	tda9950_glue_release(priv);
+
+	irqflags = IRQF_TRIGGER_FALLING;
+	if (glue)
+		irqflags = glue->irq_flags;
+
+	ret = devm_request_threaded_irq(dev, client->irq, NULL, tda9950_irq,
+					irqflags | IRQF_SHARED | IRQF_ONESHOT,
+					dev_name(&client->dev), priv);
+	if (ret < 0)
+		return ret;
+
+	priv->notify = cec_notifier_get(priv->hdmi);
+	if (!priv->notify)
+		return -ENOMEM;
+
+	ret = cec_register_adapter(priv->adap, priv->hdmi);
+	if (ret < 0) {
+		cec_notifier_put(priv->notify);
+		return ret;
+	}
+
+	/*
+	 * CEC documentation says we must not call cec_delete_adapter
+	 * after a successful call to cec_register_adapter().
+	 */
+	devm_remove_action(dev, tda9950_cec_del, priv);
+
+	cec_register_cec_notifier(priv->adap, priv->notify);
+
+	return 0;
+}
+
+static int tda9950_remove(struct i2c_client *client)
+{
+	struct tda9950_priv *priv = i2c_get_clientdata(client);
+
+	cec_unregister_adapter(priv->adap);
+	cec_notifier_put(priv->notify);
+
+	return 0;
+}
+
+static struct i2c_device_id tda9950_ids[] = {
+	{ "tda9950", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, tda9950_ids);
+
+static struct i2c_driver tda9950_driver = {
+	.probe = tda9950_probe,
+	.remove = tda9950_remove,
+	.driver = {
+		.name = "tda9950",
+	},
+	.id_table = tda9950_ids,
+};
+
+module_i2c_driver(tda9950_driver);
+
+MODULE_AUTHOR("Russell King <[e-mail]>");
+MODULE_DESCRIPTION("TDA9950/TDA998x Consumer Electronics Control Driver");
+MODULE_LICENSE("GPL v2");

include/linux/platform_data/tda9950.h

···
+#ifndef LINUX_PLATFORM_DATA_TDA9950_H
+#define LINUX_PLATFORM_DATA_TDA9950_H
+
+struct device;
+
+struct tda9950_glue {
+	struct device *parent;
+	unsigned long irq_flags;
+	void *data;
+	int (*init)(void *);
+	void (*exit)(void *);
+	int (*open)(void *);
+	void (*release)(void *);
+};
+
+#endif