1 files changed, 449 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-emev2.c b/drivers/i2c/busses/i2c-emev2.c
new file mode 100644
index 0000000000..5574094104
--- /dev/null
+++ b/drivers/i2c/busses/i2c-emev2.c
@@ -0,0 +1,449 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * I2C driver for the Renesas EMEV2 SoC
+ *
+ * Copyright (C) 2015 Wolfram Sang <wsa@sang-engineering.com>
+ * Copyright 2013 Codethink Ltd.
+ * Copyright 2010-2015 Renesas Electronics Corporation
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/sched.h>
+
+/* I2C Registers */
+#define I2C_OFS_IICACT0		0x00	/* start */
+#define I2C_OFS_IIC0		0x04	/* shift */
+#define I2C_OFS_IICC0		0x08	/* control */
+#define I2C_OFS_SVA0		0x0c	/* slave address */
+#define I2C_OFS_IICCL0		0x10	/* clock select */
+#define I2C_OFS_IICX0		0x14	/* extension */
+#define I2C_OFS_IICS0		0x18	/* status */
+#define I2C_OFS_IICSE0		0x1c	/* status For emulation */
+#define I2C_OFS_IICF0		0x20	/* IIC flag */
+
+/* I2C IICACT0 Masks */
+#define I2C_BIT_IICE0		0x0001
+
+/* I2C IICC0 Masks */
+#define I2C_BIT_LREL0		0x0040
+#define I2C_BIT_WREL0		0x0020
+#define I2C_BIT_SPIE0		0x0010
+#define I2C_BIT_WTIM0		0x0008
+#define I2C_BIT_ACKE0		0x0004
+#define I2C_BIT_STT0		0x0002
+#define I2C_BIT_SPT0		0x0001
+
+/* I2C IICCL0 Masks */
+#define I2C_BIT_SMC0		0x0008
+#define I2C_BIT_DFC0		0x0004
+
+/* I2C IICSE0 Masks */
+#define I2C_BIT_MSTS0		0x0080
+#define I2C_BIT_ALD0		0x0040
+#define I2C_BIT_EXC0		0x0020
+#define I2C_BIT_COI0		0x0010
+#define I2C_BIT_TRC0		0x0008
+#define I2C_BIT_ACKD0		0x0004
+#define I2C_BIT_STD0		0x0002
+#define I2C_BIT_SPD0		0x0001
+
+/* I2C IICF0 Masks */
+#define I2C_BIT_STCF		0x0080
+#define I2C_BIT_IICBSY		0x0040
+#define I2C_BIT_STCEN		0x0002
+#define I2C_BIT_IICRSV		0x0001
+
+struct em_i2c_device {
+	void __iomem *base;
+	struct i2c_adapter adap;
+	struct completion msg_done;
+	struct clk *sclk;
+	struct i2c_client *slave;
+	int irq;
+};
+
+static inline void em_clear_set_bit(struct em_i2c_device *priv, u8 clear, u8 set, u8 reg)
+{
+	writeb((readb(priv->base + reg) & ~clear) | set, priv->base + reg);
+}
+
+static int em_i2c_wait_for_event(struct em_i2c_device *priv)
+{
+	unsigned long time_left;
+	int status;
+
+	reinit_completion(&priv->msg_done);
+
+	time_left = wait_for_completion_timeout(&priv->msg_done, priv->adap.timeout);
+
+	if (!time_left)
+		return -ETIMEDOUT;
+
+	status = readb(priv->base + I2C_OFS_IICSE0);
+	return status & I2C_BIT_ALD0 ? -EAGAIN : status;
+}
+
+static void em_i2c_stop(struct em_i2c_device *priv)
+{
+	/* Send Stop condition */
+	em_clear_set_bit(priv, 0, I2C_BIT_SPT0 | I2C_BIT_SPIE0, I2C_OFS_IICC0);
+
+	/* Wait for stop condition */
+	em_i2c_wait_for_event(priv);
+}
+
+static void em_i2c_reset(struct i2c_adapter *adap)
+{
+	struct em_i2c_device *priv = i2c_get_adapdata(adap);
+	int retr;
+
+	/* If I2C active */
+	if (readb(priv->base + I2C_OFS_IICACT0) & I2C_BIT_IICE0) {
+		/* Disable I2C operation */
+		writeb(0, priv->base + I2C_OFS_IICACT0);
+
+		retr = 1000;
+		while (readb(priv->base + I2C_OFS_IICACT0) == 1 && retr)
+			retr--;
+		WARN_ON(retr == 0);
+	}
+
+	/* Transfer mode set */
+	writeb(I2C_BIT_DFC0, priv->base + I2C_OFS_IICCL0);
+
+	/* Can Issue start without detecting a stop, Reservation disabled. */
+	writeb(I2C_BIT_STCEN | I2C_BIT_IICRSV, priv->base + I2C_OFS_IICF0);
+
+	/* I2C enable, 9 bit interrupt mode */
+	writeb(I2C_BIT_WTIM0, priv->base + I2C_OFS_IICC0);
+
+	/* Enable I2C operation */
+	writeb(I2C_BIT_IICE0, priv->base + I2C_OFS_IICACT0);
+
+	retr = 1000;
+	while (readb(priv->base + I2C_OFS_IICACT0) == 0 && retr)
+		retr--;
+	WARN_ON(retr == 0);
+}
+
+static int __em_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msg,
+				int stop)
+{
+	struct em_i2c_device *priv = i2c_get_adapdata(adap);
+	int count, status, read = !!(msg->flags & I2C_M_RD);
+
+	/* Send start condition */
+	em_clear_set_bit(priv, 0, I2C_BIT_ACKE0 | I2C_BIT_WTIM0, I2C_OFS_IICC0);
+	em_clear_set_bit(priv, 0, I2C_BIT_STT0, I2C_OFS_IICC0);
+
+	/* Send slave address and R/W type */
+	writeb(i2c_8bit_addr_from_msg(msg), priv->base + I2C_OFS_IIC0);
+
+	/* Wait for transaction */
+	status = em_i2c_wait_for_event(priv);
+	if (status < 0)
+		goto out_reset;
+
+	/* Received NACK (result of setting slave address and R/W) */
+	if (!(status & I2C_BIT_ACKD0)) {
+		em_i2c_stop(priv);
+		goto out;
+	}
+
+	/* Extra setup for read transactions */
+	if (read) {
+		/* 8 bit interrupt mode */
+		em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_ACKE0, I2C_OFS_IICC0);
+		em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_WREL0, I2C_OFS_IICC0);
+
+		/* Wait for transaction */
+		status = em_i2c_wait_for_event(priv);
+		if (status < 0)
+			goto out_reset;
+	}
+
+	/* Send / receive data */
+	for (count = 0; count < msg->len; count++) {
+		if (read) { /* Read transaction */
+			msg->buf[count] = readb(priv->base + I2C_OFS_IIC0);
+			em_clear_set_bit(priv, 0, I2C_BIT_WREL0, I2C_OFS_IICC0);
+
+		} else { /* Write transaction */
+			/* Received NACK */
+			if (!(status & I2C_BIT_ACKD0)) {
+				em_i2c_stop(priv);
+				goto out;
+			}
+
+			/* Write data */
+			writeb(msg->buf[count], priv->base + I2C_OFS_IIC0);
+		}
+
+		/* Wait for R/W transaction */
+		status = em_i2c_wait_for_event(priv);
+		if (status < 0)
+			goto out_reset;
+	}
+
+	if (stop)
+		em_i2c_stop(priv);
+
+	return count;
+
+out_reset:
+	em_i2c_reset(adap);
+out:
+	return status < 0 ? status : -ENXIO;
+}
+
+static int em_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+	int num)
+{
+	struct em_i2c_device *priv = i2c_get_adapdata(adap);
+	int ret, i;
+
+	if (readb(priv->base + I2C_OFS_IICF0) & I2C_BIT_IICBSY)
+		return -EAGAIN;
+
+	for (i = 0; i < num; i++) {
+		ret = __em_i2c_xfer(adap, &msgs[i], (i == (num - 1)));
+		if (ret < 0)
+			return ret;
+	}
+
+	/* I2C transfer completed */
+	return num;
+}
+
+static bool em_i2c_slave_irq(struct em_i2c_device *priv)
+{
+	u8 status, value;
+	enum i2c_slave_event event;
+	int ret;
+
+	if (!priv->slave)
+		return false;
+
+	status = readb(priv->base + I2C_OFS_IICSE0);
+
+	/* Extension code, do not participate */
+	if (status & I2C_BIT_EXC0) {
+		em_clear_set_bit(priv, 0, I2C_BIT_LREL0, I2C_OFS_IICC0);
+		return true;
+	}
+
+	/* Stop detected, we don't know if it's for slave or master */
+	if (status & I2C_BIT_SPD0) {
+		/* Notify slave device */
+		i2c_slave_event(priv->slave, I2C_SLAVE_STOP, &value);
+		/* Pretend we did not handle the interrupt */
+		return false;
+	}
+
+	/* Only handle interrupts addressed to us */
+	if (!(status & I2C_BIT_COI0))
+		return false;
+
+	/* Enable stop interrupts */
+	em_clear_set_bit(priv, 0, I2C_BIT_SPIE0, I2C_OFS_IICC0);
+
+	/* Transmission or Reception */
+	if (status & I2C_BIT_TRC0) {
+		if (status & I2C_BIT_ACKD0) {
+			/* 9 bit interrupt mode */
+			em_clear_set_bit(priv, 0, I2C_BIT_WTIM0, I2C_OFS_IICC0);
+
+			/* Send data */
+			event = status & I2C_BIT_STD0 ?
+				I2C_SLAVE_READ_REQUESTED :
+				I2C_SLAVE_READ_PROCESSED;
+			i2c_slave_event(priv->slave, event, &value);
+			writeb(value, priv->base + I2C_OFS_IIC0);
+		} else {
+			/* NACK, stop transmitting */
+			em_clear_set_bit(priv, 0, I2C_BIT_LREL0, I2C_OFS_IICC0);
+		}
+	} else {
+		/* 8 bit interrupt mode */
+		em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_ACKE0,
+				I2C_OFS_IICC0);
+		em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_WREL0,
+				I2C_OFS_IICC0);
+
+		if (status & I2C_BIT_STD0) {
+			i2c_slave_event(priv->slave, I2C_SLAVE_WRITE_REQUESTED,
+					&value);
+		} else {
+			/* Recv data */
+			value = readb(priv->base + I2C_OFS_IIC0);
+			ret = i2c_slave_event(priv->slave,
+					I2C_SLAVE_WRITE_RECEIVED, &value);
+			if (ret < 0)
+				em_clear_set_bit(priv, I2C_BIT_ACKE0, 0,
+						I2C_OFS_IICC0);
+		}
+	}
+
+	return true;
+}
+
+static irqreturn_t em_i2c_irq_handler(int this_irq, void *dev_id)
+{
+	struct em_i2c_device *priv = dev_id;
+
+	if (em_i2c_slave_irq(priv))
+		return IRQ_HANDLED;
+
+	complete(&priv->msg_done);
+
+	return IRQ_HANDLED;
+}
+
+static u32 em_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SLAVE;
+}
+
+static int em_i2c_reg_slave(struct i2c_client *slave)
+{
+	struct em_i2c_device *priv = i2c_get_adapdata(slave->adapter);
+
+	if (priv->slave)
+		return -EBUSY;
+
+	if (slave->flags & I2C_CLIENT_TEN)
+		return -EAFNOSUPPORT;
+
+	priv->slave = slave;
+
+	/* Set slave address */
+	writeb(slave->addr << 1, priv->base + I2C_OFS_SVA0);
+
+	return 0;
+}
+
+static int em_i2c_unreg_slave(struct i2c_client *slave)
+{
+	struct em_i2c_device *priv = i2c_get_adapdata(slave->adapter);
+
+	WARN_ON(!priv->slave);
+
+	writeb(0, priv->base + I2C_OFS_SVA0);
+
+	/*
+	 * Wait for interrupt to finish. New slave irqs cannot happen because we
+	 * cleared the slave address and, thus, only extension codes will be
+	 * detected which do not use the slave ptr.
+	 */
+	synchronize_irq(priv->irq);
+	priv->slave = NULL;
+
+	return 0;
+}
+
+static const struct i2c_algorithm em_i2c_algo = {
+	.master_xfer = em_i2c_xfer,
+	.functionality = em_i2c_func,
+	.reg_slave      = em_i2c_reg_slave,
+	.unreg_slave    = em_i2c_unreg_slave,
+};
+
+static int em_i2c_probe(struct platform_device *pdev)
+{
+	struct em_i2c_device *priv;
+	int ret;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
+
+	strscpy(priv->adap.name, "EMEV2 I2C", sizeof(priv->adap.name));
+
+	priv->sclk = devm_clk_get(&pdev->dev, "sclk");
+	if (IS_ERR(priv->sclk))
+		return PTR_ERR(priv->sclk);
+
+	ret = clk_prepare_enable(priv->sclk);
+	if (ret)
+		return ret;
+
+	priv->adap.timeout = msecs_to_jiffies(100);
+	priv->adap.retries = 5;
+	priv->adap.dev.parent = &pdev->dev;
+	priv->adap.algo = &em_i2c_algo;
+	priv->adap.owner = THIS_MODULE;
+	priv->adap.dev.of_node = pdev->dev.of_node;
+
+	init_completion(&priv->msg_done);
+
+	platform_set_drvdata(pdev, priv);
+	i2c_set_adapdata(&priv->adap, priv);
+
+	em_i2c_reset(&priv->adap);
+
+	ret = platform_get_irq(pdev, 0);
+	if (ret < 0)
+		goto err_clk;
+	priv->irq = ret;
+	ret = devm_request_irq(&pdev->dev, priv->irq, em_i2c_irq_handler, 0,
+				"em_i2c", priv);
+	if (ret)
+		goto err_clk;
+
+	ret = i2c_add_adapter(&priv->adap);
+
+	if (ret)
+		goto err_clk;
+
+	dev_info(&pdev->dev, "Added i2c controller %d, irq %d\n", priv->adap.nr,
+		 priv->irq);
+
+	return 0;
+
+err_clk:
+	clk_disable_unprepare(priv->sclk);
+	return ret;
+}
+
+static void em_i2c_remove(struct platform_device *dev)
+{
+	struct em_i2c_device *priv = platform_get_drvdata(dev);
+
+	i2c_del_adapter(&priv->adap);
+	clk_disable_unprepare(priv->sclk);
+}
+
+static const struct of_device_id em_i2c_ids[] = {
+	{ .compatible = "renesas,iic-emev2", },
+	{ }
+};
+
+static struct platform_driver em_i2c_driver = {
+	.probe = em_i2c_probe,
+	.remove_new = em_i2c_remove,
+	.driver = {
+		.name = "em-i2c",
+		.of_match_table = em_i2c_ids,
+	}
+};
+module_platform_driver(em_i2c_driver);
+
+MODULE_DESCRIPTION("EMEV2 I2C bus driver");
+MODULE_AUTHOR("Ian Molton");
+MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_DEVICE_TABLE(of, em_i2c_ids);