Date:   Sun, 1 Jul 2018 13:38:49 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Peter Rosin <peda@...ntia.se>
Cc:     wsa@...-dreams.de, robh+dt@...nel.org, afaerber@...e.de,
        linus.walleij@...aro.org, linux-i2c@...r.kernel.org,
        liuwei@...ions-semi.com, mp-cs@...ions-semi.com,
        96boards@...obotics.com, devicetree@...r.kernel.org,
        andy.shevchenko@...il.com, daniel.thompson@...aro.org,
        amit.kucheria@...aro.org, linux-arm-kernel@...ts.infradead.org,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        hzhang@...obotics.com, bdong@...obotics.com,
        manivannanece23@...il.com, thomas.liau@...ions-semi.com,
        jeff.chen@...ions-semi.com
Subject: Re: [PATCH v3 5/6] i2c: Add Actions Semiconductor Owl family S900
 I2C driver

Hi Peter,

On Sun, Jul 01, 2018 at 06:57:54AM +0200, Peter Rosin wrote:
> On June 30, 2018 3:33:29 PM GMT+02:00, Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org> wrote:
> >Add Actions Semiconductor Owl family S900 I2C driver.
> >
> >Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> >---
> > drivers/i2c/busses/Kconfig   |   7 +
> > drivers/i2c/busses/Makefile  |   1 +
> > drivers/i2c/busses/i2c-owl.c | 477 +++++++++++++++++++++++++++++++++++
> > 3 files changed, 485 insertions(+)
> > create mode 100644 drivers/i2c/busses/i2c-owl.c
> >
> >diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> >index 4f8df2ec87b1..8c8025f87ce4 100644
> >--- a/drivers/i2c/busses/Kconfig
> >+++ b/drivers/i2c/busses/Kconfig
> >@@ -762,6 +762,13 @@ config I2C_OMAP
> > 	  Like OMAP1510/1610/1710/5912 and OMAP242x.
> > 	  For details see http://www.ti.com/omap.
> > 
> >+config I2C_OWL
> >+	tristate "Actions Semiconductor Owl I2C Controller"
> >+	depends on ARCH_ACTIONS || COMPILE_TEST
> >+	help
> >+	  Say Y here if you want to use the I2C bus controller on
> >+	  the Actions Semiconductor Owl SoC's.
> >+
> > config I2C_PASEMI
> > 	tristate "PA Semi SMBus interface"
> > 	depends on PPC_PASEMI && PCI
> >diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> >index 5a869144a0c5..b71618f77880 100644
> >--- a/drivers/i2c/busses/Makefile
> >+++ b/drivers/i2c/busses/Makefile
> >@@ -76,6 +76,7 @@ obj-$(CONFIG_I2C_MXS)		+= i2c-mxs.o
> > obj-$(CONFIG_I2C_NOMADIK)	+= i2c-nomadik.o
> > obj-$(CONFIG_I2C_OCORES)	+= i2c-ocores.o
> > obj-$(CONFIG_I2C_OMAP)		+= i2c-omap.o
> >+obj-$(CONFIG_I2C_OWL)		+= i2c-owl.o
> > obj-$(CONFIG_I2C_PASEMI)	+= i2c-pasemi.o
> > obj-$(CONFIG_I2C_PCA_PLATFORM)	+= i2c-pca-platform.o
> > obj-$(CONFIG_I2C_PMCMSP)	+= i2c-pmcmsp.o
> >diff --git a/drivers/i2c/busses/i2c-owl.c
> >b/drivers/i2c/busses/i2c-owl.c
> >new file mode 100644
> >index 000000000000..144a249bf994
> >--- /dev/null
> >+++ b/drivers/i2c/busses/i2c-owl.c
> >@@ -0,0 +1,477 @@
> >+// SPDX-License-Identifier: GPL-2.0+
> >+/*
> >+ * Actions Semiconductor Owl SoC's I2C driver
> >+ *
> >+ * Copyright (c) 2014 Actions Semi Inc.
> >+ * Author: David Liu <liuwei@...ions-semi.com>
> >+ *
> >+ * Copyright (c) 2018 Linaro Ltd.
> >+ * Author: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> >+ */
> >+
> >+#include <linux/clk.h>
> >+#include <linux/delay.h>
> >+#include <linux/i2c.h>
> >+#include <linux/interrupt.h>
> >+#include <linux/io.h>
> >+#include <linux/module.h>
> >+#include <linux/of_device.h>
> >+
> >+/* I2C registers */
> >+#define OWL_I2C_REG_CTL		0x0000
> >+#define OWL_I2C_REG_CLKDIV	0x0004
> >+#define OWL_I2C_REG_STAT	0x0008
> >+#define OWL_I2C_REG_ADDR	0x000C
> >+#define OWL_I2C_REG_TXDAT	0x0010
> >+#define OWL_I2C_REG_RXDAT	0x0014
> >+#define OWL_I2C_REG_CMD		0x0018
> >+#define OWL_I2C_REG_FIFOCTL	0x001C
> >+#define OWL_I2C_REG_FIFOSTAT	0x0020
> >+#define OWL_I2C_REG_DATCNT	0x0024
> >+#define OWL_I2C_REG_RCNT	0x0028
> >+
> >+/* I2Cx_CTL Bit Mask */
> >+#define OWL_I2C_CTL_RB		BIT(1)
> >+#define OWL_I2C_CTL_GBCC(x)	(((x) & 0x3) << 2)
> >+#define	OWL_I2C_CTL_GBCC_NONE	OWL_I2C_CTL_GBCC(0)
> >+#define	OWL_I2C_CTL_GBCC_START	OWL_I2C_CTL_GBCC(1)
> >+#define	OWL_I2C_CTL_GBCC_STOP	OWL_I2C_CTL_GBCC(2)
> >+#define	OWL_I2C_CTL_GBCC_RSTART	OWL_I2C_CTL_GBCC(3)
> >+#define OWL_I2C_CTL_IRQE	BIT(5)
> >+#define OWL_I2C_CTL_EN		BIT(7)
> >+#define OWL_I2C_CTL_AE		BIT(8)
> >+#define OWL_I2C_CTL_SHSM	BIT(10)
> >+
> >+#define OWL_I2C_DIV_FACTOR(x)	((x) & 0xff)
> >+
> >+/* I2Cx_STAT Bit Mask */
> >+#define OWL_I2C_STAT_RACK	BIT(0)
> >+#define OWL_I2C_STAT_BEB	BIT(1)
> >+#define OWL_I2C_STAT_IRQP	BIT(2)
> >+#define OWL_I2C_STAT_LAB	BIT(3)
> >+#define OWL_I2C_STAT_STPD	BIT(4)
> >+#define OWL_I2C_STAT_STAD	BIT(5)
> >+#define OWL_I2C_STAT_BBB	BIT(6)
> >+#define OWL_I2C_STAT_TCB	BIT(7)
> >+#define OWL_I2C_STAT_LBST	BIT(8)
> >+#define OWL_I2C_STAT_SAMB	BIT(9)
> >+#define OWL_I2C_STAT_SRGC	BIT(10)
> >+
> >+/* I2Cx_CMD Bit Mask */
> >+#define OWL_I2C_CMD_SBE		BIT(0)
> >+#define OWL_I2C_CMD_RBE		BIT(4)
> >+#define OWL_I2C_CMD_DE		BIT(8)
> >+#define OWL_I2C_CMD_NS		BIT(9)
> >+#define OWL_I2C_CMD_SE		BIT(10)
> >+#define OWL_I2C_CMD_MSS		BIT(11)
> >+#define OWL_I2C_CMD_WRS		BIT(12)
> >+#define OWL_I2C_CMD_SECL	BIT(15)
> >+
> >+#define OWL_I2C_CMD_AS(x)	(((x) & 0x7) << 1)
> >+#define OWL_I2C_CMD_SAS(x)	(((x) & 0x7) << 5)
> >+
> >+/* I2Cx_FIFOCTL Bit Mask */
> >+#define OWL_I2C_FIFOCTL_NIB	BIT(0)
> >+#define OWL_I2C_FIFOCTL_RFR	BIT(1)
> >+#define OWL_I2C_FIFOCTL_TFR	BIT(2)
> >+
> >+/* I2Cc_FIFOSTAT Bit Mask */
> >+#define OWL_I2C_FIFOSTAT_RNB	BIT(1)
> >+#define OWL_I2C_FIFOSTAT_RFE	BIT(2)
> >+#define OWL_I2C_FIFOSTAT_TFF	BIT(5)
> >+#define OWL_I2C_FIFOSTAT_TFD	GENMASK(23, 16)
> >+#define OWL_I2C_FIFOSTAT_RFD	GENMASK(15, 8)
> >+
> >+/* I2C bus timeout */
> >+#define OWL_I2C_TIMEOUT		msecs_to_jiffies(4 * 1000)
> >+
> >+#define OWL_I2C_MAX_RETRIES	50
> >+
> >+#define OWL_I2C_DEF_SPEED_HZ	100000
> >+#define OWL_I2C_MAX_SPEED_HZ	400000
> >+
> >+struct owl_i2c_dev {
> >+	struct i2c_adapter	adap;
> >+	struct i2c_msg		*msg;
> >+	struct completion	msg_complete;
> >+	struct clk		*clk;
> >+	void __iomem		*base;
> >+	unsigned long		clk_rate;
> >+	u32			bus_freq;
> >+	u32			msg_ptr;
> >+};
> >+
> >+static void owl_i2c_update_reg(void __iomem *reg, unsigned int val,
> >bool state)
> >+{
> >+	unsigned int regval;
> >+
> >+	regval = readl(reg);
> >+
> >+	if (state)
> >+		regval |= val;
> >+	else
> >+		regval &= ~val;
> >+
> >+	writel(regval, reg);
> >+}
> >+
> >+static int owl_i2c_reset(struct owl_i2c_dev *i2c_dev)
> >+{
> >+	unsigned int val, timeout = 0;
> >+
> >+	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
> >+				OWL_I2C_CTL_EN, false);
> >+	mdelay(1);
> >+	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
> >+				OWL_I2C_CTL_EN, true);
> >+
> >+	/* Reset FIFO */
> >+	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_FIFOCTL,
> >+				OWL_I2C_FIFOCTL_RFR | OWL_I2C_FIFOCTL_TFR,
> >+				true);
> >+
> >+	/* Wait 50ms for FIFO reset complete */
> >+	do {
> >+		val = readl(i2c_dev->base + OWL_I2C_REG_FIFOCTL);
> >+		if (!(val & (OWL_I2C_FIFOCTL_RFR | OWL_I2C_FIFOCTL_TFR)))
> >+			break;
> >+		mdelay(1);
> >+	} while (timeout++ < OWL_I2C_MAX_RETRIES);
> >+
> >+	if (timeout > OWL_I2C_MAX_RETRIES) {
> >+		dev_err(&i2c_dev->adap.dev, "FIFO reset timeout");
> >+		return -ETIMEDOUT;
> >+	}
> >+
> >+	/* Clear status registers */
> >+	writel(0, i2c_dev->base + OWL_I2C_REG_STAT);
> >+
> >+	return 0;
> >+}
> >+
> >+static int owl_i2c_set_freq(struct owl_i2c_dev *i2c_dev)
> >+{
> >+	unsigned int val;
> >+
> >+	val = (i2c_dev->clk_rate + i2c_dev->bus_freq * 16 - 1) /
> >+				(i2c_dev->bus_freq * 16);
> >+
> >+	/* Set clock divider factor */
> >+	writel(OWL_I2C_DIV_FACTOR(val), i2c_dev->base + OWL_I2C_REG_CLKDIV);
> >+
> >+	return 0;
> >+}
> >+
> >+static int owl_i2c_hw_init(struct owl_i2c_dev *i2c_dev)
> >+{
> >+	int ret;
> >+
> >+	/* Reset I2C controller */
> >+	ret = owl_i2c_reset(i2c_dev);
> >+	if (ret)
> >+		return ret;
> >+
> >+	/* Set bus frequency */
> >+	return owl_i2c_set_freq(i2c_dev);
> >+}
> >+
> >+static irqreturn_t owl_i2c_interrupt(int irq, void *_dev)
> >+{
> >+	struct owl_i2c_dev *i2c_dev = _dev;
> >+	struct i2c_msg *msg = i2c_dev->msg;
> >+	unsigned int stat, fifostat;
> >+
> >+	fifostat = readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT);
> >+	if (fifostat & OWL_I2C_FIFOSTAT_RNB) {
> >+		dev_dbg(&i2c_dev->adap.dev, "received NACK from device");
> >+		goto stop;
> >+	}
> >+
> >+	stat = readl(i2c_dev->base + OWL_I2C_REG_STAT);
> >+	if (stat & OWL_I2C_STAT_BEB) {
> >+		dev_dbg(&i2c_dev->adap.dev, "bus error");
> >+		goto stop;
> >+	}
> >+
> >+	/* Handle FIFO read */
> >+	if (msg->flags & I2C_M_RD) {
> >+		while ((readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT) &
> >+				OWL_I2C_FIFOSTAT_RFE) &&
> >+				(i2c_dev->msg_ptr < msg->len)) {
> >+			msg->buf[i2c_dev->msg_ptr++] = readl(i2c_dev->base +
> >+							OWL_I2C_REG_RXDAT);
> >+		}
> >+	} else {
> >+		/* Handle the remaining bytes which were not sent */
> >+		while (!(readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT) &
> >+				OWL_I2C_FIFOSTAT_TFF) &&
> >+				i2c_dev->msg_ptr < msg->len) {
> >+			writel(msg->buf[i2c_dev->msg_ptr++], i2c_dev->base +
> >+							OWL_I2C_REG_TXDAT);
> >+		}
> >+	}
> >+
> >+stop:
> >+	/* Clear pending interrupts */
> >+	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_STAT,
> >+				OWL_I2C_STAT_IRQP, true);
> >+
> 
> Here is a read-modify-write on ..._REG_STAT from interrupt context...
> 

Will use spinlock for the entire handler.

> >+	complete_all(&i2c_dev->msg_complete);
> >+
> >+	return IRQ_HANDLED;
> >+}
> >+
> >+static u32 owl_i2c_func(struct i2c_adapter *adap)
> >+{
> >+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> >+}
> >+
> >+static int owl_i2c_check_bus_busy(struct i2c_adapter *adap)
> >+{
> >+	struct owl_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
> >+	unsigned long timeout;
> >+	unsigned int val;
> >+
> >+	/* Check for Arbitration lost */
> >+	val = readl(i2c_dev->base + OWL_I2C_REG_STAT);
> >+	if (val & OWL_I2C_STAT_LAB) {
> >+		val &= ~OWL_I2C_STAT_LAB;
> >+		writel(val, i2c_dev->base + OWL_I2C_REG_STAT);
> 
> ...and here is one from process context.
> 
> Can they cross? If not, why? Either use some locking, or add a comment explaining why this is safe.
> 

As said above, this function will be protected by spinlock.

> >+		return -EAGAIN;
> >+	}
> >+
> >+	/* Check for Bus busy */
> >+	timeout = jiffies + OWL_I2C_TIMEOUT;
> >+	while (readl(i2c_dev->base + OWL_I2C_REG_STAT) & OWL_I2C_STAT_BBB) {
> >+		if (time_after(jiffies, timeout)) {
> >+			dev_err(&adap->dev, "Bus busy timeout");
> >+			return -ETIMEDOUT;
> >+		}
> >+	}
> >+
> >+	return 0;
> >+}
> >+
> >+static int owl_i2c_master_xfer(struct i2c_adapter *adap, struct
> >i2c_msg *msgs,
> >+				int num)
> >+{
> >+	struct owl_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
> >+	struct i2c_msg *msg;
> >+	unsigned long time_left;
> >+	unsigned int i2c_cmd;
> >+	unsigned int addr;
> >+	int ret, idx;
> >+
> >+	ret = owl_i2c_hw_init(i2c_dev);
> >+	if (ret)
> >+		return ret;
> >+
> >+	ret = owl_i2c_check_bus_busy(adap);
> >+	if (ret)
> >+		return ret;
> >+
> >+	reinit_completion(&i2c_dev->msg_complete);
> >+
> >+	/* Enable I2C controller interrupt */
> >+	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
> >+				OWL_I2C_CTL_IRQE, true);
> >+
> >+	/*
> >+	 * Select: FIFO enable, Master mode, Stop enable, Data count enable,
> >+	 * Send start bit
> >+	 */
> >+	i2c_cmd = (OWL_I2C_CMD_SECL | OWL_I2C_CMD_MSS | OWL_I2C_CMD_SE
> >+			| OWL_I2C_CMD_NS | OWL_I2C_CMD_DE | OWL_I2C_CMD_SBE);
> >+
> >+	/* Handle repeated start condition */
> >+	if (num > 1) {
> >+		/* Set internal address length and enable repeated start */
> >+		i2c_cmd |= (OWL_I2C_CMD_AS(msgs[0].len + 1)
> >+				| OWL_I2C_CMD_SAS(1) | OWL_I2C_CMD_RBE);
> >+
> >+		/* Write slave address */
> >+		addr = i2c_8bit_addr_from_msg(&msgs[0]);
> >+		writel(addr, i2c_dev->base + OWL_I2C_REG_TXDAT);
> >+
> >+		/* Write internal register address */
> >+		for (idx = 0; idx < msgs[0].len; idx++)
> >+			writel(msgs[0].buf[idx], i2c_dev->base +
> >+						OWL_I2C_REG_TXDAT);
> >+
> >+		msg = &msgs[1];
> >+	} else {
> >+		/* Set address length */
> >+		i2c_cmd |= OWL_I2C_CMD_AS(1);
> >+		msg = &msgs[0];
> >+	}
> >+
> >+	i2c_dev->msg = msg;
> >+	i2c_dev->msg_ptr = 0;
> >+
> >+	/* Set data count for the message */
> >+	writel(msg->len, i2c_dev->base + OWL_I2C_REG_DATCNT);
> >+
> >+	addr = i2c_8bit_addr_from_msg(msg);
> >+	writel(addr, i2c_dev->base + OWL_I2C_REG_TXDAT);
> >+
> >+	if (!(msg->flags & I2C_M_RD)) {
> >+		/* Write data to FIFO */
> >+		for (idx = 0; idx < msg->len; idx++) {
> >+			/* Check for FIFO full */
> >+			if (readl(i2c_dev->base + OWL_I2C_REG_FIFOSTAT)
> >+					& OWL_I2C_FIFOSTAT_TFF)
> >+				break;
> >+
> >+			writel(msg->buf[idx],
> >+					i2c_dev->base + OWL_I2C_REG_TXDAT);
> >+		}
> >+
> >+		i2c_dev->msg_ptr = idx;
> >+	}
> >+
> >+	/* Ignore the NACK if needed */
> >+	if (msg->flags & I2C_M_IGNORE_NAK)
> >+		owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_FIFOCTL,
> >+				OWL_I2C_FIFOCTL_NIB, true);
> >+	else
> >+		owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_FIFOCTL,
> >+				OWL_I2C_FIFOCTL_NIB, false);
> >+
> >+	/* Start the transfer */
> >+	writel(i2c_cmd, i2c_dev->base + OWL_I2C_REG_CMD);
> >+
> >+	time_left = wait_for_completion_timeout(&i2c_dev->msg_complete,
> >+						adap->timeout);
> >+	if (time_left == 0) {
> >+		dev_err(&adap->dev, "Transaction timed out");
> >+		/* Send stop condition and release the bus */
> >+		owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
> >+			OWL_I2C_CTL_GBCC_STOP | OWL_I2C_CTL_RB, true);
> >+		ret = -ETIMEDOUT;
> >+	}
> >+
> >+	/*
> >+	 * By default, 0 will be returned if interrupt occurred but no
> >+	 * read or write happened. Else if msg_ptr equals to message length,
> >+	 * message count will be returned.
> >+	 */
> 
> Zero is never a valid return value for this function. It has to be either num or a negative error. So, this comment is bad, which makes me assume the code is too. I didn't bother to check any further...
> 

hmm, okay. Can you please suggest an error value for this case? I mean
when the handler got triggered but no read/write happened.

Thanks,
Mani

> Cheers,
> Peter
> 
> >+	if (i2c_dev->msg_ptr == msg->len)
> >+		ret = num;
> >+
> >+	/* Disable I2C controller */
> >+	owl_i2c_update_reg(i2c_dev->base + OWL_I2C_REG_CTL,
> >+				OWL_I2C_CTL_EN, false);
> >+
> >+	return ret;
> >+}
> >+
> >+static const struct i2c_algorithm owl_i2c_algorithm = {
> >+	.master_xfer    = owl_i2c_master_xfer,
> >+	.functionality  = owl_i2c_func,
> >+};
> >+
> >+static const struct i2c_adapter_quirks owl_i2c_quirks = {
> >+	.flags		= I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST,
> >+	.max_read_len   = 240,
> >+	.max_write_len  = 240,
> >+	.max_comb_1st_msg_len = 6,
> >+	.max_comb_2nd_msg_len = 240,
> >+};
> >+
> >+static int owl_i2c_probe(struct platform_device *pdev)
> >+{
> >+	struct device *dev = &pdev->dev;
> >+	struct owl_i2c_dev *i2c_dev;
> >+	struct resource *res;
> >+	int ret, irq;
> >+
> >+	i2c_dev = devm_kzalloc(dev, sizeof(*i2c_dev), GFP_KERNEL);
> >+	if (!i2c_dev)
> >+		return -ENOMEM;
> >+
> >+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >+	i2c_dev->base = devm_ioremap_resource(dev, res);
> >+	if (IS_ERR(i2c_dev->base))
> >+		return PTR_ERR(i2c_dev->base);
> >+
> >+	irq = platform_get_irq(pdev, 0);
> >+	if (irq < 0) {
> >+		dev_err(dev, "failed to get IRQ number\n");
> >+		return irq;
> >+	}
> >+
> >+	if (of_property_read_u32(dev->of_node, "clock-frequency",
> >+					&i2c_dev->bus_freq))
> >+		i2c_dev->bus_freq = OWL_I2C_DEF_SPEED_HZ;
> >+
> >+	/* We support only frequencies of 100k and 400k for now */
> >+	if (i2c_dev->bus_freq != OWL_I2C_DEF_SPEED_HZ &&
> >+			i2c_dev->bus_freq > OWL_I2C_MAX_SPEED_HZ) {
> >+		dev_err(dev, "invalid clock-frequency %d\n", i2c_dev->bus_freq);
> >+		return -EINVAL;
> >+	}
> >+
> >+	i2c_dev->clk = devm_clk_get(dev, NULL);
> >+	if (IS_ERR(i2c_dev->clk)) {
> >+		dev_err(dev, "failed to get clock\n");
> >+		return PTR_ERR(i2c_dev->clk);
> >+	}
> >+
> >+	ret = clk_prepare_enable(i2c_dev->clk);
> >+	if (ret)
> >+		return ret;
> >+
> >+	i2c_dev->clk_rate = clk_get_rate(i2c_dev->clk);
> >+	if (!i2c_dev->clk_rate) {
> >+		dev_err(dev, "input clock rate should not be zero\n");
> >+		ret = -EINVAL;
> >+		goto disable_clk;
> >+	}
> >+
> >+	init_completion(&i2c_dev->msg_complete);
> >+	i2c_dev->adap.owner = THIS_MODULE;
> >+	i2c_dev->adap.algo = &owl_i2c_algorithm;
> >+	i2c_dev->adap.timeout = OWL_I2C_TIMEOUT;
> >+	i2c_dev->adap.quirks = &owl_i2c_quirks;
> >+	i2c_dev->adap.dev.parent = dev;
> >+	i2c_dev->adap.dev.of_node = dev->of_node;
> >+	snprintf(i2c_dev->adap.name, sizeof(i2c_dev->adap.name),
> >+			"%s", "OWL I2C adapter");
> >+	i2c_set_adapdata(&i2c_dev->adap, i2c_dev);
> >+
> >+	platform_set_drvdata(pdev, i2c_dev);
> >+
> >+	ret = devm_request_irq(dev, irq, owl_i2c_interrupt, 0, pdev->name,
> >+				i2c_dev);
> >+	if (ret) {
> >+		dev_err(dev, "failed to request irq %d\n", irq);
> >+		goto disable_clk;
> >+	}
> >+
> >+	return i2c_add_adapter(&i2c_dev->adap);
> >+
> >+disable_clk:
> >+	clk_disable_unprepare(i2c_dev->clk);
> >+
> >+	return ret;
> >+}
> >+
> >+static const struct of_device_id owl_i2c_of_match[] = {
> >+	{.compatible = "actions,s900-i2c"},
> >+	{ /* sentinel */ }
> >+};
> >+MODULE_DEVICE_TABLE(of, owl_i2c_of_match);
> >+
> >+static struct platform_driver owl_i2c_driver = {
> >+	.probe		= owl_i2c_probe,
> >+	.driver		= {
> >+		.name	= "owl-i2c",
> >+		.of_match_table = of_match_ptr(owl_i2c_of_match),
> >+	},
> >+};
> >+module_platform_driver(owl_i2c_driver);
> >+
> >+MODULE_AUTHOR("David Liu <liuwei@...ions-semi.com>");
> >+MODULE_AUTHOR("Manivannan Sadhasivam
> ><manivannan.sadhasivam@...aro.org>");
> >+MODULE_DESCRIPTION("Actions Semiconductor Owl SoC's I2C driver");
> >+MODULE_LICENSE("GPL");
> 

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