Hello Brendan,

please find some review notes below.

On 11/05/2016 03:58 AM, Brendan Higgins wrote:

Please try to keep the list ordered, it would be better, if you
add I2C_ASPEED before I2C_AT91.

Same comment as above, put it in front of i2c-at91.o

I don't think that the copyright dated by 2020 in advance is legal here.

Please change it to the expected ...-2016 value.

+ *  Copyright 2016 IBM Corporation
+ *  Copyright 2016 Google, Inc.
+ *
+ *  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/kernel.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/completion.h>
+#include <linux/slab.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/err.h>
+#include <linux/clk.h>

Please sort the headers alphabetically.

+
+/* I2C Register */
+#define ASPEED_I2C_FUN_CTRL_REG				0x00
+#define ASPEED_I2C_AC_TIMING_REG1			0x04
+#define ASPEED_I2C_AC_TIMING_REG2			0x08
+#define ASPEED_I2C_INTR_CTRL_REG			0x0c
+#define ASPEED_I2C_INTR_STS_REG				0x10
+#define ASPEED_I2C_CMD_REG				0x14
+#define ASPEED_I2C_DEV_ADDR_REG				0x18
+#define ASPEED_I2C_BYTE_BUF_REG				0x20
+#define ASPEED_I2C_OFFSET_START				0x40

Unused macro, please remove.

+#define ASPEED_I2C_OFFSET_INCREMENT			0x40

Unused macro, please remove.

+
+#define ASPEED_I2C_NUM_BUS 14
+
+/* Global Register Definition */
+/* 0x00 : I2C Interrupt Status Register  */
+/* 0x08 : I2C Interrupt Target Assignment  */
+
+/* Device Register Definition */
+/* 0x00 : I2CD Function Control Register  */
+#define ASPEED_I2CD_MULTI_MASTER_DIS			BIT(15)

Unused macro, please remove.

+#define ASPEED_I2CD_SDA_DRIVE_1T_EN			BIT(8)

Unused macro, please remove.

+#define ASPEED_I2CD_M_SDA_DRIVE_1T_EN			BIT(7)
+#define ASPEED_I2CD_M_HIGH_SPEED_EN			BIT(6)
+#define ASPEED_I2CD_SLAVE_EN				BIT(1)

Unused macro, please remove. You add slave support, may be you
need this control, but it is unused.

+#define ASPEED_I2CD_MASTER_EN				BIT(0)
+
+/* 0x08 : I2CD Clock and AC Timing Control Register #2 */
+#define ASPEED_NO_TIMEOUT_CTRL				0
+
+
+/* 0x0c : I2CD Interrupt Control Register &
+ * 0x10 : I2CD Interrupt Status Register
+ *
+ * These share bit definitions, so use the same values for the enable &
+ * status bits.
+ */
+#define ASPEED_I2CD_INTR_SDA_DL_TIMEOUT			BIT(14)
+#define ASPEED_I2CD_INTR_BUS_RECOVER_DONE		BIT(13)
+#define ASPEED_I2CD_INTR_SLAVE_MATCH			BIT(7)
+#define ASPEED_I2CD_INTR_SCL_TIMEOUT			BIT(6)
+#define ASPEED_I2CD_INTR_ABNORMAL			BIT(5)
+#define ASPEED_I2CD_INTR_NORMAL_STOP			BIT(4)
+#define ASPEED_I2CD_INTR_ARBIT_LOSS			BIT(3)
+#define ASPEED_I2CD_INTR_RX_DONE			BIT(2)
+#define ASPEED_I2CD_INTR_TX_NAK				BIT(1)
+#define ASPEED_I2CD_INTR_TX_ACK				BIT(0)
+
+/* 0x14 : I2CD Command/Status Register   */
+#define ASPEED_I2CD_SCL_LINE_STS			BIT(18)
+#define ASPEED_I2CD_SDA_LINE_STS			BIT(17)
+#define ASPEED_I2CD_BUS_BUSY_STS			BIT(16)
+#define ASPEED_I2CD_BUS_RECOVER_CMD			BIT(11)
+
+/* Command Bit */
+#define ASPEED_I2CD_M_STOP_CMD				BIT(5)
+#define ASPEED_I2CD_M_S_RX_CMD_LAST			BIT(4)
+#define ASPEED_I2CD_M_RX_CMD				BIT(3)
+#define ASPEED_I2CD_S_TX_CMD				BIT(2)
+#define ASPEED_I2CD_M_TX_CMD				BIT(1)
+#define ASPEED_I2CD_M_START_CMD				BIT(0)
+
+/* 0x18 : I2CD Slave Device Address Register   */
+#define ASPEED_I2CD_DEV_ADDR_MASK			GENMASK(6, 0)
+
+enum aspeed_i2c_slave_state {
+	ASPEED_I2C_SLAVE_START,
+	ASPEED_I2C_SLAVE_READ_REQUESTED,
+	ASPEED_I2C_SLAVE_READ_PROCESSED,
+	ASPEED_I2C_SLAVE_WRITE_REQUESTED,
+	ASPEED_I2C_SLAVE_WRITE_RECEIVED,
+	ASPEED_I2C_SLAVE_STOP,
+};
+
+struct aspeed_i2c_bus {
+	struct i2c_adapter		adap;
+	struct device			*dev;
+	void __iomem			*base;
+	spinlock_t			lock;
+	struct completion		cmd_complete;
+	int				irq;
+	/* Transaction state. */
+	struct i2c_msg			*msg;
+	int				msg_pos;
+	u32				cmd_err;
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+	struct i2c_client		*slave;
+	enum aspeed_i2c_slave_state	slave_state;
+#endif
+};
+
+struct aspeed_i2c_controller {
+	struct device		*dev;
+	void __iomem		*base;
+	int			irq;
+	struct irq_domain	*irq_domain;
+};
+
+static inline void aspeed_i2c_write(struct aspeed_i2c_bus *bus, u32 val,
+				    u32 reg)
+{
+	writel(val, bus->base + reg);
+}
+
+static inline u32 aspeed_i2c_read(struct aspeed_i2c_bus *bus, u32 reg)
+{
+	return readl(bus->base + reg);
+}
+
+static u8 aspeed_i2c_recover_bus(struct aspeed_i2c_bus *bus)

The function may return errors as negative numbers, please
change its return type to 'int'.

+{
+	u32 command;
+	unsigned long time_left;
+	unsigned long flags;
+	int ret = 0;

Please whenever possible use "reverse christmas tree" order while
declaring local variables, this applies to all functions, here it
should be

	unsigned long time_left, flags;
	int ret = 0;
	u32 command;

+
+	spin_lock_irqsave(&bus->lock, flags);
+	command = aspeed_i2c_read(bus, ASPEED_I2C_CMD_REG);
+	/* Bus is idle: no recovery needed. */
+	if ((command & ASPEED_I2CD_SDA_LINE_STS) &&
+	    (command & ASPEED_I2CD_SCL_LINE_STS))
+		goto out;
+
+	dev_dbg(bus->dev, "bus hung (state %x), attempting recovery\n",
+		command);
+
+	/* Bus held: put bus in stop state. */
+	if ((command & ASPEED_I2CD_SDA_LINE_STS) &&
+	    !(command & ASPEED_I2CD_SCL_LINE_STS)) {
+		aspeed_i2c_write(bus, ASPEED_I2CD_M_STOP_CMD,
+				 ASPEED_I2C_CMD_REG);
+		reinit_completion(&bus->cmd_complete);
+		spin_unlock_irqrestore(&bus->lock, flags);
+
+		time_left = wait_for_completion_interruptible_timeout(
+				&bus->cmd_complete, bus->adap.timeout * HZ);
+
+		spin_lock_irqsave(&bus->lock, flags);
+		if (time_left == 0)
+			ret = -ETIMEDOUT;
+		else if (bus->cmd_err)
+			ret = -EIO;

Since you use wait_for_completion_interruptible_timeout(), please
handle possible -ERESTARTSYS error if the execution is interrupted.

You have 5 quite similar wait_for_completion_interruptible_timeout()
functions in the driver, please add it to all of them, or you may
think how to wrap it properly into a new function.

+	/* Bus error. */
+	} else if (!(command & ASPEED_I2CD_SDA_LINE_STS)) {

You don't need to introduce "else if" here, at this point
!(command & ASPEED_I2CD_SDA_LINE_STS) expression is always true.

Please drop dev_dbg("bus hang") statement from above (or put it to
an if-branch from two ones described below) and for simplicity
rearrange the code:

	if (command & ASPEED_I2CD_SDA_LINE_STS) {
		/* Bus is idle: no recovery needed. */
		if (command & ASPEED_I2CD_SCL_LINE_STS)
			goto out;

		/* Bus held: put bus in stop state. */
		.....
	} else {
		/* Bus error. */
		.....
	}

+		aspeed_i2c_write(bus, ASPEED_I2CD_BUS_RECOVER_CMD,
+				 ASPEED_I2C_CMD_REG);
+		reinit_completion(&bus->cmd_complete);
+		spin_unlock_irqrestore(&bus->lock, flags);
+
+		time_left = wait_for_completion_interruptible_timeout(
+				&bus->cmd_complete, bus->adap.timeout * HZ);
+
+		spin_lock_irqsave(&bus->lock, flags);
+		if (time_left == 0)
+			ret = -ETIMEDOUT;
+		else if (bus->cmd_err)
+			ret = -EIO;
+		/* Recovery failed. */
+		else if (!(aspeed_i2c_read(bus, ASPEED_I2C_CMD_REG) &
+			   ASPEED_I2CD_SDA_LINE_STS))
+			ret = -EIO;
+	}
+
+out:
+	spin_unlock_irqrestore(&bus->lock, flags);

Please insert an empty line here to improve readability.

+	return ret;
+}
+
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+static bool aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus)
+{
+	bool irq_handled = true;
+	u32 command;
+	u32 irq_status;
+	u32 status_ack = 0;
+	u8 value;
+	struct i2c_client *slave = bus->slave;

See a comment above about order of declared local variables.

+
+	spin_lock(&bus->lock);
+	if (!slave) {
+		irq_handled = false;
+		goto out;
+	}

Add an empty line here.

+	command = aspeed_i2c_read(bus, ASPEED_I2C_CMD_REG);
+	irq_status = aspeed_i2c_read(bus, ASPEED_I2C_INTR_STS_REG);
+
+	/* Slave was requested, restart state machine. */
+	if (irq_status & ASPEED_I2CD_INTR_SLAVE_MATCH) {
+		status_ack |= ASPEED_I2CD_INTR_SLAVE_MATCH;
+		bus->slave_state = ASPEED_I2C_SLAVE_START;
+	}

Add an empty line here.

+	/* Slave is not currently active, irq was for someone else. */
+	if (bus->slave_state == ASPEED_I2C_SLAVE_STOP) {
+		irq_handled = false;
+		goto out;
+	}
+
+	dev_dbg(bus->dev, "slave irq status 0x%08x, cmd 0x%08x\n",
+		irq_status, command);
+
+	/* Slave was sent something. */
+	if (irq_status & ASPEED_I2CD_INTR_RX_DONE) {
+		value = aspeed_i2c_read(bus, ASPEED_I2C_BYTE_BUF_REG) >> 8;
+		/* Handle address frame. */
+		if (bus->slave_state == ASPEED_I2C_SLAVE_START) {
+			if (value & 0x1)
+				bus->slave_state =
+						ASPEED_I2C_SLAVE_READ_REQUESTED;
+			else
+				bus->slave_state =
+						ASPEED_I2C_SLAVE_WRITE_REQUESTED;
+		}
+		status_ack |= ASPEED_I2CD_INTR_RX_DONE;
+	}
+
+	/* Slave was asked to stop. */
+	if (irq_status & ASPEED_I2CD_INTR_NORMAL_STOP) {
+		status_ack |= ASPEED_I2CD_INTR_NORMAL_STOP;
+		bus->slave_state = ASPEED_I2C_SLAVE_STOP;
+	}

Add an empty line here.

+	if (irq_status & ASPEED_I2CD_INTR_TX_NAK) {
+		status_ack |= ASPEED_I2CD_INTR_TX_NAK;
+		bus->slave_state = ASPEED_I2C_SLAVE_STOP;
+	}
+
+	if (bus->slave_state == ASPEED_I2C_SLAVE_READ_REQUESTED) {
+		if (irq_status & ASPEED_I2CD_INTR_TX_ACK)
+			dev_err(bus->dev, "Unexpected ACK on read request.\n");
+		bus->slave_state = ASPEED_I2C_SLAVE_READ_PROCESSED;
+
+		i2c_slave_event(slave, I2C_SLAVE_READ_REQUESTED, &value);
+		aspeed_i2c_write(bus, value, ASPEED_I2C_BYTE_BUF_REG);
+		aspeed_i2c_write(bus, ASPEED_I2CD_S_TX_CMD, ASPEED_I2C_CMD_REG);
+	} else if (bus->slave_state == ASPEED_I2C_SLAVE_READ_PROCESSED) {
+		status_ack |= ASPEED_I2CD_INTR_TX_ACK;
+		if (!(irq_status & ASPEED_I2CD_INTR_TX_ACK))
+			dev_err(bus->dev,
+				"Expected ACK after processed read.\n");
+		i2c_slave_event(slave, I2C_SLAVE_READ_PROCESSED, &value);
+		aspeed_i2c_write(bus, value, ASPEED_I2C_BYTE_BUF_REG);
+		aspeed_i2c_write(bus, ASPEED_I2CD_S_TX_CMD, ASPEED_I2C_CMD_REG);
+	} else if (bus->slave_state == ASPEED_I2C_SLAVE_WRITE_REQUESTED) {
+		bus->slave_state = ASPEED_I2C_SLAVE_WRITE_RECEIVED;
+		i2c_slave_event(slave, I2C_SLAVE_WRITE_REQUESTED, &value);
+	} else if (bus->slave_state == ASPEED_I2C_SLAVE_WRITE_RECEIVED) {
+		i2c_slave_event(slave, I2C_SLAVE_WRITE_RECEIVED, &value);
+	} else if (bus->slave_state == ASPEED_I2C_SLAVE_STOP) {
+		i2c_slave_event(slave, I2C_SLAVE_STOP, &value);
+	}

Please change this if-else-if-else-if-... construction of state machine
changes into switch-case.

+
+	if (status_ack != irq_status)
+		dev_err(bus->dev,
+			"irq handled != irq. expected %x, but was %x\n",
+			irq_status, status_ack);
+	aspeed_i2c_write(bus, status_ack, ASPEED_I2C_INTR_STS_REG);
+
+out:
+	spin_unlock(&bus->lock);
+	return irq_handled;
+}
+#endif
+
+static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
+{
+	const u32 errs = ASPEED_I2CD_INTR_ARBIT_LOSS |
+		ASPEED_I2CD_INTR_ABNORMAL |
+		ASPEED_I2CD_INTR_SCL_TIMEOUT |
+		ASPEED_I2CD_INTR_SDA_DL_TIMEOUT |
+		ASPEED_I2CD_INTR_TX_NAK;

You don't need this local variable, it is used only once, please
declare a macro and put it somewhere close to ASPEED_I2CD_INTR_*
macro in the beginning of the file.

+	u32 irq_status;
+
+	spin_lock(&bus->lock);
+	irq_status = aspeed_i2c_read(bus, ASPEED_I2C_INTR_STS_REG);
+	bus->cmd_err = irq_status & errs;
+
+	dev_dbg(bus->dev, "master irq status 0x%08x\n", irq_status);
+
+	/* No message to transfer. */
+	if (bus->cmd_err ||
+	    (irq_status & ASPEED_I2CD_INTR_NORMAL_STOP) ||
+	    (irq_status & ASPEED_I2CD_INTR_BUS_RECOVER_DONE)) {
+		complete(&bus->cmd_complete);
+		goto out;
+	} else if (!bus->msg || bus->msg_pos >= bus->msg->len)
+		goto out;
+
+	if ((bus->msg->flags & I2C_M_RD) &&
+	    (irq_status & ASPEED_I2CD_INTR_RX_DONE)) {
+		bus->msg->buf[bus->msg_pos++] = aspeed_i2c_read(
+				bus, ASPEED_I2C_BYTE_BUF_REG) >> 8;
+		if (bus->msg_pos + 1 < bus->msg->len)
+			aspeed_i2c_write(bus, ASPEED_I2CD_M_RX_CMD,
+					 ASPEED_I2C_CMD_REG);
+		else if (bus->msg_pos < bus->msg->len)
+			aspeed_i2c_write(bus, ASPEED_I2CD_M_RX_CMD |
+				      ASPEED_I2CD_M_S_RX_CMD_LAST,
+				      ASPEED_I2C_CMD_REG);
+	} else if (!(bus->msg->flags & I2C_M_RD) &&
+		   (irq_status & ASPEED_I2CD_INTR_TX_ACK)) {
+		aspeed_i2c_write(bus, bus->msg->buf[bus->msg_pos++],
+			      ASPEED_I2C_BYTE_BUF_REG);
+		aspeed_i2c_write(bus, ASPEED_I2CD_M_TX_CMD, ASPEED_I2C_CMD_REG);
+	}
+
+	/* Transmission complete: notify caller. */
+	if (bus->msg_pos >= bus->msg->len)
+		complete(&bus->cmd_complete);
+out:
+	aspeed_i2c_write(bus, irq_status, ASPEED_I2C_INTR_STS_REG);
+	spin_unlock(&bus->lock);

Please insert an empty line here to improve readability.

+	return true;
+}
+
+static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id)
+{
+	struct aspeed_i2c_bus *bus = dev_id;
+
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+	if (aspeed_i2c_slave_irq(bus)) {
+		dev_dbg(bus->dev, "irq handled by slave.\n");
+		return IRQ_HANDLED;
+	}
+#endif

Please insert an empty line here to improve readability.

+	if (aspeed_i2c_master_irq(bus)) {
+		dev_dbg(bus->dev, "irq handled by master.\n");
+		return IRQ_HANDLED;
+	}

Please insert an empty line here to improve readability.

+	dev_err(bus->dev, "irq not handled properly!\n");
+	return IRQ_HANDLED;

If interrupt is not handled, return IRQ_NONE.

+}
+
+static int aspeed_i2c_master_single_xfer(struct i2c_adapter *adap,
+				      struct i2c_msg *msg)
+{
+	struct aspeed_i2c_bus *bus = adap->algo_data;
+	unsigned long flags;
+	u8 slave_addr;
+	u32 command = ASPEED_I2CD_M_START_CMD | ASPEED_I2CD_M_TX_CMD;
+	int ret = msg->len;
+	unsigned long time_left;
+
+	spin_lock_irqsave(&bus->lock, flags);
+	bus->msg = msg;
+	bus->msg_pos = 0;
+	slave_addr = msg->addr << 1;

Please insert an empty line here to improve readability.

+	if (msg->flags & I2C_M_RD) {
+		slave_addr |= 1;
+		command |= ASPEED_I2CD_M_RX_CMD;
+		if (msg->len == 1)
+			command |= ASPEED_I2CD_M_S_RX_CMD_LAST;
+	}

Please insert an empty line here to improve readability.

+	aspeed_i2c_write(bus, slave_addr, ASPEED_I2C_BYTE_BUF_REG);
+	aspeed_i2c_write(bus, command, ASPEED_I2C_CMD_REG);
+	reinit_completion(&bus->cmd_complete);
+	spin_unlock_irqrestore(&bus->lock, flags);
+
+	time_left = wait_for_completion_interruptible_timeout(
+			&bus->cmd_complete, bus->adap.timeout * HZ * msg->len);
+	if (time_left == 0)
+		return -ETIMEDOUT;
+
+	spin_lock_irqsave(&bus->lock, flags);
+	if (bus->cmd_err)
+		ret = -EIO;

Please insert an empty line here to improve readability.

+	bus->msg = NULL;
+	spin_unlock_irqrestore(&bus->lock, flags);
+
+	return ret;
+}
+
+static int aspeed_i2c_master_xfer(struct i2c_adapter *adap,
+				  struct i2c_msg *msgs, int num)
+{
+	struct aspeed_i2c_bus *bus = adap->algo_data;
+	int ret;
+	int i;
+	unsigned long flags;
+	unsigned long time_left;
+
+	/* If bus is busy, attempt recovery. We assume a single master
+	 * environment.
+	 */
+	if (aspeed_i2c_read(bus, ASPEED_I2C_CMD_REG) &
+	    ASPEED_I2CD_BUS_BUSY_STS) {
+		ret = aspeed_i2c_recover_bus(bus);
+		if (ret)
+			return ret;
+	}
+
+	for (i = 0; i < num; i++) {
+		ret = aspeed_i2c_master_single_xfer(adap, &msgs[i]);
+		if (ret < 0)
+			break;
+		/* TODO: Support other forms of I2C protocol mangling. */
+		if (msgs[i].flags & I2C_M_STOP) {
+			spin_lock_irqsave(&bus->lock, flags);
+			aspeed_i2c_write(bus, ASPEED_I2CD_M_STOP_CMD,
+				      ASPEED_I2C_CMD_REG);
+			reinit_completion(&bus->cmd_complete);
+			spin_unlock_irqrestore(&bus->lock, flags);
+
+			time_left = wait_for_completion_interruptible_timeout(
+					&bus->cmd_complete,
+					bus->adap.timeout * HZ);
+			if (time_left == 0)
+				return -ETIMEDOUT;
+		}
+	}
+
+	spin_lock_irqsave(&bus->lock, flags);
+	aspeed_i2c_write(bus, ASPEED_I2CD_M_STOP_CMD, ASPEED_I2C_CMD_REG);
+	reinit_completion(&bus->cmd_complete);
+	spin_unlock_irqrestore(&bus->lock, flags);
+
+	time_left = wait_for_completion_interruptible_timeout(
+			&bus->cmd_complete, bus->adap.timeout * HZ);
+	if (time_left == 0)
+		return -ETIMEDOUT;
+
+	/* If nothing went wrong, return number of messages transferred. */
+	if (ret < 0)
+		return ret;
+	else
+		return i;
+}
+
+static u32 aspeed_i2c_functionality(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA;
+}
+
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+static int aspeed_i2c_reg_slave(struct i2c_client *client)
+{
+	struct aspeed_i2c_bus *bus;
+	unsigned long flags;
+	u32 addr_reg_val;
+	u32 func_ctrl_reg_val;
+
+	bus = client->adapter->algo_data;
+	spin_lock_irqsave(&bus->lock, flags);
+	if (bus->slave) {
+		spin_unlock_irqrestore(&bus->lock, flags);
+		return -EINVAL;
+	}
+
+	/* Set slave addr. */
+	addr_reg_val = aspeed_i2c_read(bus, ASPEED_I2C_DEV_ADDR_REG);
+	addr_reg_val &= ~ASPEED_I2CD_DEV_ADDR_MASK;
+	addr_reg_val |= client->addr & ASPEED_I2CD_DEV_ADDR_MASK;
+	aspeed_i2c_write(bus, addr_reg_val, ASPEED_I2C_DEV_ADDR_REG);
+
+	/* Switch from master mode to slave mode. */
+	func_ctrl_reg_val = aspeed_i2c_read(bus, ASPEED_I2C_FUN_CTRL_REG);
+	func_ctrl_reg_val &= ~ASPEED_I2CD_MASTER_EN;
+	func_ctrl_reg_val |= ASPEED_I2CD_SLAVE_EN;
+	aspeed_i2c_write(bus, func_ctrl_reg_val, ASPEED_I2C_FUN_CTRL_REG);
+
+	bus->slave = client;
+	bus->slave_state = ASPEED_I2C_SLAVE_STOP;
+	spin_unlock_irqrestore(&bus->lock, flags);

Please insert an empty line here to improve readability.

+	return 0;
+}
+
+static int aspeed_i2c_unreg_slave(struct i2c_client *client)
+{
+	struct aspeed_i2c_bus *bus = client->adapter->algo_data;
+	unsigned long flags;
+	u32 func_ctrl_reg_val;
+
+	spin_lock_irqsave(&bus->lock, flags);
+	if (!bus->slave) {
+		spin_unlock_irqrestore(&bus->lock, flags);
+		return -EINVAL;
+	}
+
+	/* Switch from slave mode to master mode. */
+	func_ctrl_reg_val = aspeed_i2c_read(bus, ASPEED_I2C_FUN_CTRL_REG);
+	func_ctrl_reg_val &= ~ASPEED_I2CD_SLAVE_EN;
+	func_ctrl_reg_val |= ASPEED_I2CD_MASTER_EN;
+	aspeed_i2c_write(bus, func_ctrl_reg_val, ASPEED_I2C_FUN_CTRL_REG);
+
+	bus->slave = NULL;
+	spin_unlock_irqrestore(&bus->lock, flags);

Please insert an empty line here to improve readability.

+	return 0;
+}
+#endif
+
+static const struct i2c_algorithm aspeed_i2c_algo = {
+	.master_xfer	= aspeed_i2c_master_xfer,
+	.functionality	= aspeed_i2c_functionality,
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+	.reg_slave	= aspeed_i2c_reg_slave,
+	.unreg_slave	= aspeed_i2c_unreg_slave,
+#endif
+};
+
+static u32 aspeed_i2c_get_clk_reg_val(u32 divider_ratio)
+{
+	unsigned int inc = 0, div;
+	u32 scl_low, scl_high, data;
+
+	for (div = 0; divider_ratio >= 16; div++) {
+		inc |= (divider_ratio & 1);
+		divider_ratio >>= 1;
+	}

Please insert an empty line here to improve readability.

+	divider_ratio += inc;
+	scl_low = (divider_ratio >> 1) - 1;
+	scl_high = divider_ratio - scl_low - 2;
+	data = 0x77700300 | (scl_high << 16) | (scl_low << 12) | div;
+	return data;
+}
+
+static int aspeed_i2c_init_clk(struct aspeed_i2c_bus *bus,
+			    struct platform_device *pdev)
+{
+	struct clk *pclk;
+	u32 clk_freq;
+	u32 divider_ratio;
+	int ret;
+
+	pclk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(pclk)) {
+		dev_err(&pdev->dev, "clk_get failed\n");
+		return PTR_ERR(pclk);
+	}
+	ret = of_property_read_u32(pdev->dev.of_node,
+			"clock-frequency", &clk_freq);
+	if (ret < 0) {
+		dev_err(&pdev->dev,
+				"Could not read clock-frequency property\n");
+		clk_freq = 100000;
+	}
+	divider_ratio = clk_get_rate(pclk) / clk_freq;
+	/* We just need the clock rate, we don't actually use the clk object. */
+	devm_clk_put(&pdev->dev, pclk);

Does the controller have a clock supply? If yes, shall the clock be
enabled before issuing command to the controller?

+
+	/* Set AC Timing */
+	if (clk_freq / 1000 > 400) {
+		aspeed_i2c_write(bus, aspeed_i2c_read(bus,
+						      ASPEED_I2C_FUN_CTRL_REG) |
+				ASPEED_I2CD_M_HIGH_SPEED_EN |
+				ASPEED_I2CD_M_SDA_DRIVE_1T_EN |
+				ASPEED_I2CD_SDA_DRIVE_1T_EN,
+				ASPEED_I2C_FUN_CTRL_REG);
+
+		aspeed_i2c_write(bus, 0x3, ASPEED_I2C_AC_TIMING_REG2);
+		aspeed_i2c_write(bus, aspeed_i2c_get_clk_reg_val(divider_ratio),
+			      ASPEED_I2C_AC_TIMING_REG1);
+	} else {
+		aspeed_i2c_write(bus, aspeed_i2c_get_clk_reg_val(divider_ratio),
+			      ASPEED_I2C_AC_TIMING_REG1);
+		aspeed_i2c_write(bus, ASPEED_NO_TIMEOUT_CTRL,
+				 ASPEED_I2C_AC_TIMING_REG2);
+	}
+
+	return 0;
+}
+
+static void noop(struct irq_data *data) { }
+
+static struct irq_chip aspeed_i2c_irqchip = {
+	.name		= "ast-i2c",
+	.irq_unmask	= noop,
+	.irq_mask	= noop,

Thomas or Marc should review the irqchip code for correctness,
inform them.

+};
+
+static int aspeed_i2c_probe_bus(struct platform_device *pdev)
+{
+	struct aspeed_i2c_bus *bus;
+	struct aspeed_i2c_controller *controller =
+			dev_get_drvdata(pdev->dev.parent);

How do you ensure that "controller" device _driver_ is initialized
at this point? This is a critical race condition.

+	struct resource *res;
+	int ret, irq;
+	u32 hwirq;
+
+	bus = devm_kzalloc(&pdev->dev, sizeof(*bus), GFP_KERNEL);
+	if (!bus)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	bus->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(bus->base))
+		return PTR_ERR(bus->base);
+
+	bus->irq = platform_get_irq(pdev, 0);
+	if (bus->irq < 0)
+		return -ENXIO;

Remove check for error here, on error it will be returned by the
following devm_request_irq().

+	ret = of_property_read_u32(pdev->dev.of_node, "interrupts", &hwirq);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "no I2C 'interrupts' property\n");
+		return -ENXIO;

return -EINVAL;

+	}
+	irq = irq_create_mapping(controller->irq_domain, hwirq);
+	irq_set_chip_data(irq, controller);
+	irq_set_chip_and_handler(irq, &aspeed_i2c_irqchip, handle_simple_irq);
+	ret = devm_request_irq(&pdev->dev, bus->irq, aspeed_i2c_bus_irq,
+			0, dev_name(&pdev->dev), bus);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to request interrupt\n");
+		return -ENXIO;

return ret;

In general I'm very surprised to see irqchip declaration and
initialization as a part of an I2C bus driver.

What is it used for? If you keep it, most probably IRQCHIP maintainers
(Thomas, Marc) shall review and ack the code.

+	}
+
+	/* Initialize the I2C adapter */
+	spin_lock_init(&bus->lock);
+	init_completion(&bus->cmd_complete);
+	bus->adap.owner = THIS_MODULE;
+	bus->adap.retries = 0;
+	bus->adap.timeout = 5;

I don't think that this is a correct value, because here timeout unit
is in jiffies. Please update it here and everywhere in the driver,
where you use the value.

+	bus->adap.algo = &aspeed_i2c_algo;
+	bus->adap.algo_data = bus;
+	bus->adap.dev.parent = &pdev->dev;
+	bus->adap.dev.of_node = pdev->dev.of_node;
+	snprintf(bus->adap.name, sizeof(bus->adap.name), "Aspeed i2c");
+
+	bus->dev = &pdev->dev;
+
+	/* reset device: disable master & slave functions */
+	aspeed_i2c_write(bus, 0, ASPEED_I2C_FUN_CTRL_REG);
+
+	ret = aspeed_i2c_init_clk(bus, pdev);
+	if (ret < 0)
+		return ret;

I'm not sure here, probably you start leaking resources allocated by
irq_create_mapping().

+
+	/* Enable Master Mode */
+	aspeed_i2c_write(bus, aspeed_i2c_read(bus, ASPEED_I2C_FUN_CTRL_REG) |
+		      ASPEED_I2CD_MASTER_EN |
+		      ASPEED_I2CD_MULTI_MASTER_DIS, ASPEED_I2C_FUN_CTRL_REG);
+
+	/* Set interrupt generation of I2C controller */
+	aspeed_i2c_write(bus, ASPEED_I2CD_INTR_SDA_DL_TIMEOUT |
+			ASPEED_I2CD_INTR_BUS_RECOVER_DONE |
+			ASPEED_I2CD_INTR_SCL_TIMEOUT |
+			ASPEED_I2CD_INTR_ABNORMAL |
+			ASPEED_I2CD_INTR_NORMAL_STOP |
+			ASPEED_I2CD_INTR_ARBIT_LOSS |
+			ASPEED_I2CD_INTR_RX_DONE |
+			ASPEED_I2CD_INTR_TX_NAK |
+			ASPEED_I2CD_INTR_TX_ACK,

Please declare a macro which combines all enabled interrupt events, and
put it somewhere close to ASPEED_I2CD_INTR_* macro definitions.

+			ASPEED_I2C_INTR_CTRL_REG);
+
+	ret = i2c_add_adapter(&bus->adap);
+	if (ret < 0)
+		return -ENXIO;

Incorrect, you should propogate the error and "return ret;" here.

+
+	platform_set_drvdata(pdev, bus);
+
+	dev_info(bus->dev, "i2c bus %d registered, irq %d\n",
+			bus->adap.nr, bus->irq);
+
+	return 0;
+}
+
+static int aspeed_i2c_remove_bus(struct platform_device *pdev)
+{
+	struct aspeed_i2c_bus *bus = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&bus->adap);

Please insert an empty line here to improve readability.

+	return 0;
+}
+
+static const struct of_device_id aspeed_i2c_bus_of_table[] = {
+	{ .compatible = "aspeed,ast2400-i2c-bus", },
+	{ .compatible = "aspeed,ast2500-i2c-bus", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, aspeed_i2c_bus_of_table);
+
+static struct platform_driver aspeed_i2c_bus_driver = {
+	.probe		= aspeed_i2c_probe_bus,
+	.remove		= aspeed_i2c_remove_bus,
+	.driver		= {
+		.name		= "ast-i2c-bus",
+		.of_match_table	= aspeed_i2c_bus_of_table,
+	},
+};
+
+static void aspeed_i2c_controller_irq(struct irq_desc *desc)
+{
+	struct aspeed_i2c_controller *c = irq_desc_get_handler_data(desc);
+	unsigned long p, status;
+	unsigned int bus_irq;
+
+	status = readl(c->base);
+	for_each_set_bit(p, &status, ASPEED_I2C_NUM_BUS) {
+		bus_irq = irq_find_mapping(c->irq_domain, p);
+		generic_handle_irq(bus_irq);
+	}

This is a processing of a cascaded interrupt, you should wrap
the code into chained_irq_enter()/chained_irq_exit().

+}
+
+static int aspeed_i2c_probe_controller(struct platform_device *pdev)
+{
+	struct aspeed_i2c_controller *controller;
+	struct device_node *np;
+	struct resource *res;
+
+	controller = kzalloc(sizeof(*controller), GFP_KERNEL);
+	if (!controller)
+		return -ENOMEM;

You don't free the allocated memory on driver release, please convert
allocation to devm_kzalloc().

+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	controller->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(controller->base))
+		return PTR_ERR(controller->base);
+
+	controller->irq = platform_get_irq(pdev, 0);
+	if (controller->irq < 0)
+		return -ENXIO;
+
+	controller->irq_domain = irq_domain_add_linear(pdev->dev.of_node,
+			ASPEED_I2C_NUM_BUS, &irq_domain_simple_ops, NULL);
+	if (!controller->irq_domain)
+		return -ENXIO;

return -ENOMEM is the correct error here.

Please insert an empty line here to improve readability.

+	controller->irq_domain->name = "ast-i2c-domain";
+
+	irq_set_chained_handler_and_data(controller->irq,
+			aspeed_i2c_controller_irq, controller);
+
+	controller->dev = &pdev->dev;
+
+	platform_set_drvdata(pdev, controller);
+
+	dev_info(controller->dev, "i2c controller registered, irq %d\n",
+			controller->irq);
+
+	for_each_child_of_node(pdev->dev.of_node, np) {
+		of_platform_device_create(np, NULL, &pdev->dev);
+		of_node_put(np);

This is invalid use of of_node_put(np) inside for_each_child_of_node().

Just remove it to make the statement valid.

+	}
+
+	return 0;
+}
+
+static int aspeed_i2c_remove_controller(struct platform_device *pdev)
+{
+	struct aspeed_i2c_controller *controller = platform_get_drvdata(pdev);
+
+	irq_domain_remove(controller->irq_domain);

Please insert an empty line here to improve readability.

+	return 0;
+}
+
+static const struct of_device_id aspeed_i2c_controller_of_table[] = {
+	{ .compatible = "aspeed,ast2400-i2c-controller", },
+	{ .compatible = "aspeed,ast2500-i2c-controller", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, aspeed_i2c_controller_of_table);
+
+static struct platform_driver aspeed_i2c_controller_driver = {
+	.probe		= aspeed_i2c_probe_controller,
+	.remove		= aspeed_i2c_remove_controller,
+	.driver		= {
+		.name		= "ast-i2c-controller",
+		.of_match_table	= aspeed_i2c_controller_of_table,
+	},
+};
+
+static int __init aspeed_i2c_driver_init(void)
+{
+	int ret;
+
+	ret = platform_driver_register(&aspeed_i2c_controller_driver);
+	if (ret < 0)
+		return ret;

Please insert an empty line here to improve readability.

+	return platform_driver_register(&aspeed_i2c_bus_driver);

No, on error you must unregister &aspeed_i2c_controller_driver.

+}
+module_init(aspeed_i2c_driver_init);
+
+static void __exit aspeed_i2c_driver_exit(void)
+{
+	platform_driver_unregister(&aspeed_i2c_bus_driver);
+	platform_driver_unregister(&aspeed_i2c_controller_driver);
+}
+module_exit(aspeed_i2c_driver_exit);
+
+MODULE_AUTHOR("Brendan Higgins [off-list ref]");
+MODULE_DESCRIPTION("Aspeed I2C Bus Driver");
+MODULE_LICENSE("GPL");