Date:   Fri, 17 Mar 2017 11:42:50 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     M'boumba Cedric Madianga <cedric.madianga@...il.com>,
        wsa@...-dreams.de, robh+dt@...nel.org, mcoquelin.stm32@...il.com,
        alexandre.torgue@...com, linus.walleij@...aro.org,
        pierre-yves.mordret@...com, linux@...linux.org.uk,
        linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5] i2c: i2c-stm32f7: add driver

On 03/17/2017 10:58 AM, M'boumba Cedric Madianga wrote:
> This patch adds initial support for the STM32F7 I2C controller.
> 
> Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@...il.com>
> ---
>  drivers/i2c/busses/Kconfig       |  10 +
>  drivers/i2c/busses/Makefile      |   1 +
>  drivers/i2c/busses/i2c-stm32f7.c | 562 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 573 insertions(+)
>  create mode 100644 drivers/i2c/busses/i2c-stm32f7.c
> 
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index 8adc0f1..ab0caec 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -897,6 +897,16 @@ config I2C_STM32F4
>  	  This driver can also be built as module. If so, the module
>  	  will be called i2c-stm32f4.
>  
> +config I2C_STM32F7
> +	tristate "STMicroelectronics STM32F7 I2C support"
> +	depends on ARCH_STM32 || COMPILE_TEST
> +	help
> +	  Enable this option to add support for STM32 I2C controller embedded
> +	  in STM32F7 SoCs.
> +
> +	  This driver can also be built as module. If so, the module
> +	  will be called i2c-stm32f7.
> +
>  config I2C_STU300
>  	tristate "ST Microelectronics DDC I2C interface"
>  	depends on MACH_U300
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index 30b6085..5449ece 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -86,6 +86,7 @@ obj-$(CONFIG_I2C_SIMTEC)	+= i2c-simtec.o
>  obj-$(CONFIG_I2C_SIRF)		+= i2c-sirf.o
>  obj-$(CONFIG_I2C_ST)		+= i2c-st.o
>  obj-$(CONFIG_I2C_STM32F4)	+= i2c-stm32f4.o
> +obj-$(CONFIG_I2C_STM32F7)	+= i2c-stm32f7.o
>  obj-$(CONFIG_I2C_STU300)	+= i2c-stu300.o
>  obj-$(CONFIG_I2C_SUN6I_P2WI)	+= i2c-sun6i-p2wi.o
>  obj-$(CONFIG_I2C_TEGRA)		+= i2c-tegra.o
> diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
> new file mode 100644
> index 0000000..844a98b
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-stm32f7.c
> @@ -0,0 +1,562 @@
> +/*
> + * Driver for STMicroelectronics STM32F7 I2C controller
> + *
> + * This I2C controller is described in the STM32F75xxx and STM32F74xxx Soc
> + * reference manual.
> + * Please see below a link to the documentation:
> + * http://www.st.com/resource/en/reference_manual/dm00124865.pdf
> + *
> + * Copyright (C) M'boumba Cedric Madianga 2017
> + * Author: M'boumba Cedric Madianga <cedric.madianga@...il.com>
> + *
> + * This driver is based on i2c-stm32f4.c
> + *
> + * License terms:  GNU General Public License (GPL), version 2
> + */
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/platform_device.h>
> +#include <linux/reset.h>
> +
> +#include "i2c-stm32.h"
> +
> +/* STM32F7 I2C registers */
> +#define STM32F7_I2C_CR1				0x00
> +#define STM32F7_I2C_CR2				0x04
> +#define STM32F7_I2C_TIMINGR			0x10
> +#define STM32F7_I2C_ISR				0x18
> +#define STM32F7_I2C_ICR				0x1C
> +#define STM32F7_I2C_RXDR			0x24
> +#define STM32F7_I2C_TXDR			0x28
> +
> +/* STM32F7 I2C control 1 */
> +#define STM32F7_I2C_CR1_ERRIE			BIT(7)
> +#define STM32F7_I2C_CR1_TCIE			BIT(6)
> +#define STM32F7_I2C_CR1_STOPIE			BIT(5)
> +#define STM32F7_I2C_CR1_NACKIE			BIT(4)
> +#define STM32F7_I2C_CR1_ADDRIE			BIT(3)
> +#define STM32F7_I2C_CR1_RXIE			BIT(2)
> +#define STM32F7_I2C_CR1_TXIE			BIT(1)
> +#define STM32F7_I2C_CR1_PE			BIT(0)
> +#define STM32F7_I2C_ALL_IRQ_MASK		(STM32F7_I2C_CR1_ERRIE \
> +						| STM32F7_I2C_CR1_TCIE \
> +						| STM32F7_I2C_CR1_STOPIE \
> +						| STM32F7_I2C_CR1_NACKIE \
> +						| STM32F7_I2C_CR1_RXIE \
> +						| STM32F7_I2C_CR1_TXIE)
> +
> +/* STM32F7 I2C control 2 */
> +#define STM32F7_I2C_CR2_RELOAD			BIT(24)
> +#define STM32F7_I2C_CR2_NBYTES_MASK		GENMASK(23, 16)
> +#define STM32F7_I2C_CR2_NBYTES(n)		(((n) & 0xff) << 16)
> +#define STM32F7_I2C_CR2_NACK			BIT(15)
> +#define STM32F7_I2C_CR2_STOP			BIT(14)
> +#define STM32F7_I2C_CR2_START			BIT(13)
> +#define STM32F7_I2C_CR2_RD_WRN			BIT(10)
> +#define STM32F7_I2C_CR2_SADD7_MASK		GENMASK(7, 1)
> +#define STM32F7_I2C_CR2_SADD7(n)		(((n) & 0x7f) << 1)
> +
> +/* STM32F7 I2C Interrupt Status */
> +#define STM32F7_I2C_ISR_BUSY			BIT(15)
> +#define STM32F7_I2C_ISR_ARLO			BIT(9)
> +#define STM32F7_I2C_ISR_BERR			BIT(8)
> +#define STM32F7_I2C_ISR_TCR			BIT(7)
> +#define STM32F7_I2C_ISR_TC			BIT(6)
> +#define STM32F7_I2C_ISR_STOPF			BIT(5)
> +#define STM32F7_I2C_ISR_NACKF			BIT(4)
> +#define STM32F7_I2C_ISR_RXNE			BIT(2)
> +#define STM32F7_I2C_ISR_TXIS			BIT(1)
> +
> +/* STM32F7 I2C Interrupt Clear */
> +#define STM32F7_I2C_ICR_ARLOCF			BIT(9)
> +#define STM32F7_I2C_ICR_BERRCF			BIT(8)
> +#define STM32F7_I2C_ICR_STOPCF			BIT(5)
> +#define STM32F7_I2C_ICR_NACKCF			BIT(4)
> +
> +#define STM32F7_I2C_MAX_LEN			0xff
> +
> +/**
> + * struct stm32f7_i2c_msg - client specific data
> + * @addr: 8-bit slave addr, including r/w bit
> + * @count: number of bytes to be transferred
> + * @buf: data buffer
> + * @result: result of the transfer
> + * @stop: last I2C msg to be sent, i.e. STOP to be generated
> + */
> +struct stm32f7_i2c_msg {
> +	u8 addr;
> +	u32 count;
> +	u8 *buf;
> +	int result;
> +	bool stop;
> +};
> +
> +/**
> + * struct stm32f7_i2c_dev - private data of the controller
> + * @adap: I2C adapter for this controller
> + * @dev: device for this controller
> + * @base: virtual memory area
> + * @complete: completion of I2C message
> + * @clk: hw i2c clock
> + * @speed: I2C clock frequency of the controller. Standard, Fast or Fast+
> + * @msg: Pointer to data to be written
> + * @msg_num: number of I2C messages to be executed
> + * @msg_id: message identifiant
> + * @f7_msg: customized i2c msg for driver usage
> + */
> +struct stm32f7_i2c_dev {
> +	struct i2c_adapter adap;
> +	struct device *dev;
> +	void __iomem *base;
> +	struct completion complete;
> +	struct clk *clk;
> +	int speed;
> +	struct i2c_msg *msg;
> +	unsigned int msg_num;
> +	unsigned int msg_id;
> +	struct stm32f7_i2c_msg f7_msg;
> +};
> +
> +static inline void stm32f7_i2c_set_bits(void __iomem *reg, u32 mask)
> +{
> +	writel_relaxed(readl_relaxed(reg) | mask, reg);
> +}
> +
> +static inline void stm32f7_i2c_clr_bits(void __iomem *reg, u32 mask)
> +{
> +	writel_relaxed(readl_relaxed(reg) & ~mask, reg);
> +}
> +
> +static int stm32f7_i2c_hw_config(struct stm32f7_i2c_dev *i2c_dev)
> +{
> +	struct device_node *of_node = i2c_dev->dev->of_node;
> +	u32 timing;
> +	int ret;
> +
> +	ret = of_property_read_u32(of_node, "st,i2c-timing", &timing);
> +	if (ret) {
> +		dev_err(i2c_dev->dev, "Error: missing i2c timing property\n");
> +		return ret;
> +	}
> +
> +	/* Timing settings */
> +	writel_relaxed(timing, i2c_dev->base + STM32F7_I2C_TIMINGR);

Hi,

Using a register value in DT is quite ugly since the requirement to calculate the timings
is quite easy, and well documented.

I wrote it for Zephyr, you can find it here :
https://github.com/zephyrproject-rtos/zephyr/blob/master/drivers/i2c/i2c_stm32lx.c#L31

Another point, maybe you should find a better name for the driver, since this I2C IP is share
with the STM32Lx also and is not tied to STM32F7.

Thanks,
Neil

> +
> +	/* Enable I2C */
> +	writel_relaxed(STM32F7_I2C_CR1_PE, i2c_dev->base + STM32F7_I2C_CR1);
> +
> +	return 0;
> +}
> +
> +static void stm32f7_i2c_write_tx_data(struct stm32f7_i2c_dev *i2c_dev)
> +{
> +	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
> +	void __iomem *base = i2c_dev->base;
> +
> +	if (f7_msg->count) {
> +		writeb_relaxed(*f7_msg->buf++, base + STM32F7_I2C_TXDR);
> +		f7_msg->count--;
> +	}
> +}
> +
> +static void stm32f7_i2c_read_rx_data(struct stm32f7_i2c_dev *i2c_dev)
> +{
> +	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
> +	void __iomem *base = i2c_dev->base;
> +
> +	if (f7_msg->count) {
> +		*f7_msg->buf++ = readb_relaxed(base + STM32F7_I2C_RXDR);
> +		f7_msg->count--;
> +	}
> +}
> +
> +static void stm32f7_i2c_reload(struct stm32f7_i2c_dev *i2c_dev)
> +{
> +	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
> +	u32 cr2;
> +
> +	cr2 = readl_relaxed(i2c_dev->base + STM32F7_I2C_CR2);
> +
> +	cr2 &= ~STM32F7_I2C_CR2_NBYTES_MASK;
> +	if (f7_msg->count > STM32F7_I2C_MAX_LEN) {
> +		cr2 |= STM32F7_I2C_CR2_NBYTES(STM32F7_I2C_MAX_LEN);
> +	} else {
> +		cr2 &= ~STM32F7_I2C_CR2_RELOAD;
> +		cr2 |= STM32F7_I2C_CR2_NBYTES(f7_msg->count);
> +	}
> +
> +	writel_relaxed(cr2, i2c_dev->base + STM32F7_I2C_CR2);
> +}
> +
> +static int stm32f7_i2c_wait_free_bus(struct stm32f7_i2c_dev *i2c_dev)
> +{
> +	u32 status;
> +	int ret;
> +
> +	ret = readl_relaxed_poll_timeout(i2c_dev->base + STM32F7_I2C_ISR,
> +					 status,
> +					 !(status & STM32F7_I2C_ISR_BUSY),
> +					 10, 1000);
> +	if (ret) {
> +		dev_dbg(i2c_dev->dev, "bus busy\n");
> +		ret = -EBUSY;
> +	}
> +
> +	return ret;
> +}
> +
> +static void stm32f7_i2c_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
> +				 struct i2c_msg *msg)
> +{
> +	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
> +	void __iomem *base = i2c_dev->base;
> +	u32 cr1, cr2;
> +
> +	f7_msg->addr = msg->addr;
> +	f7_msg->buf = msg->buf;
> +	f7_msg->count = msg->len;
> +	f7_msg->result = 0;
> +	f7_msg->stop = (i2c_dev->msg_id >= i2c_dev->msg_num - 1);
> +
> +	reinit_completion(&i2c_dev->complete);
> +
> +	cr1 = readl_relaxed(base + STM32F7_I2C_CR1);
> +	cr2 = readl_relaxed(base + STM32F7_I2C_CR2);
> +
> +	/* Set transfer direction */
> +	cr2 &= ~STM32F7_I2C_CR2_RD_WRN;
> +	if (msg->flags & I2C_M_RD)
> +		cr2 |= STM32F7_I2C_CR2_RD_WRN;
> +
> +	/* Set slave address */
> +	cr2 &= ~STM32F7_I2C_CR2_SADD7_MASK;
> +	cr2 |= STM32F7_I2C_CR2_SADD7(f7_msg->addr);
> +
> +	/* Set nb bytes to transfer and reload if needed */
> +	cr2 &= ~(STM32F7_I2C_CR2_NBYTES_MASK | STM32F7_I2C_CR2_RELOAD);
> +	if (f7_msg->count > STM32F7_I2C_MAX_LEN) {
> +		cr2 |= STM32F7_I2C_CR2_NBYTES(STM32F7_I2C_MAX_LEN);
> +		cr2 |= STM32F7_I2C_CR2_RELOAD;
> +	} else {
> +		cr2 |= STM32F7_I2C_CR2_NBYTES(f7_msg->count);
> +	}
> +
> +	/* Enable NACK, STOP, error and transfer complete interrupts */
> +	cr1 |= STM32F7_I2C_CR1_ERRIE | STM32F7_I2C_CR1_TCIE |
> +		STM32F7_I2C_CR1_STOPIE | STM32F7_I2C_CR1_NACKIE;
> +
> +	/* Clear TX/RX interrupt */
> +	cr1 &= ~(STM32F7_I2C_CR1_RXIE | STM32F7_I2C_CR1_TXIE);
> +
> +	/* Enable RX/TX interrupt according to msg direction */
> +	if (msg->flags & I2C_M_RD)
> +		cr1 |= STM32F7_I2C_CR1_RXIE;
> +	else
> +		cr1 |= STM32F7_I2C_CR1_TXIE;
> +
> +	/* Configure Start/Repeated Start */
> +	cr2 |= STM32F7_I2C_CR2_START;
> +
> +	/* Write configurations registers */
> +	writel_relaxed(cr1, base + STM32F7_I2C_CR1);
> +	writel_relaxed(cr2, base + STM32F7_I2C_CR2);
> +}
> +
> +static void stm32f7_i2c_disable_irq(struct stm32f7_i2c_dev *i2c_dev, u32 mask)
> +{
> +	stm32f7_i2c_clr_bits(i2c_dev->base + STM32F7_I2C_CR1, mask);
> +}
> +
> +static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
> +{
> +	struct stm32f7_i2c_dev *i2c_dev = data;
> +	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
> +	void __iomem *base = i2c_dev->base;
> +	u32 status, mask;
> +
> +	status = readl_relaxed(i2c_dev->base + STM32F7_I2C_ISR);
> +
> +	/* Tx empty */
> +	if (status & STM32F7_I2C_ISR_TXIS)
> +		stm32f7_i2c_write_tx_data(i2c_dev);
> +
> +	/* RX not empty */
> +	if (status & STM32F7_I2C_ISR_RXNE)
> +		stm32f7_i2c_read_rx_data(i2c_dev);
> +
> +	/* NACK received */
> +	if (status & STM32F7_I2C_ISR_NACKF) {
> +		dev_dbg(i2c_dev->dev, "<%s>: Receive NACK\n", __func__);
> +		writel_relaxed(STM32F7_I2C_ICR_NACKCF, base + STM32F7_I2C_ICR);
> +		f7_msg->result = -EBADE;
> +	}
> +
> +	/* STOP detection flag */
> +	if (status & STM32F7_I2C_ISR_STOPF) {
> +		/* Disable interrupts */
> +		stm32f7_i2c_disable_irq(i2c_dev, STM32F7_I2C_ALL_IRQ_MASK);
> +
> +		/* Clear STOP flag */
> +		writel_relaxed(STM32F7_I2C_ICR_STOPCF, base + STM32F7_I2C_ICR);
> +
> +		complete(&i2c_dev->complete);
> +	}
> +
> +	/* Transfer complete */
> +	if (status & STM32F7_I2C_ISR_TC) {
> +		if (f7_msg->stop) {
> +			mask = STM32F7_I2C_CR2_STOP;
> +			stm32f7_i2c_set_bits(base + STM32F7_I2C_CR2, mask);
> +		} else {
> +			i2c_dev->msg_id++;
> +			i2c_dev->msg++;
> +			stm32f7_i2c_xfer_msg(i2c_dev, i2c_dev->msg);
> +		}
> +	}
> +
> +	/*
> +	 * Transfer Complete Reload: 255 data bytes have been transferred
> +	 * We have to prepare the I2C controller to transfer the remaining
> +	 * data
> +	 */
> +	if (status & STM32F7_I2C_ISR_TCR)
> +		stm32f7_i2c_reload(i2c_dev);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
> +{
> +	struct stm32f7_i2c_dev *i2c_dev = data;
> +	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
> +	void __iomem *base = i2c_dev->base;
> +	struct device *dev = i2c_dev->dev;
> +	u32 status;
> +
> +	status = readl_relaxed(i2c_dev->base + STM32F7_I2C_ISR);
> +
> +	/* Bus error */
> +	if (status & STM32F7_I2C_ISR_BERR) {
> +		dev_err(dev, "<%s>: Bus error\n", __func__);
> +		writel_relaxed(STM32F7_I2C_ICR_BERRCF, base + STM32F7_I2C_ICR);
> +		f7_msg->result = -EIO;
> +	}
> +
> +	/* Arbitration loss */
> +	if (status & STM32F7_I2C_ISR_ARLO) {
> +		dev_err(dev, "<%s>: Arbitration loss\n", __func__);
> +		writel_relaxed(STM32F7_I2C_ICR_ARLOCF, base + STM32F7_I2C_ICR);
> +		f7_msg->result = -EAGAIN;
> +	}
> +
> +	stm32f7_i2c_disable_irq(i2c_dev, STM32F7_I2C_ALL_IRQ_MASK);
> +
> +	complete(&i2c_dev->complete);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int stm32f7_i2c_xfer(struct i2c_adapter *i2c_adap,
> +			    struct i2c_msg msgs[], int num)
> +{
> +	struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap);
> +	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
> +	unsigned long timeout;
> +	int ret;
> +
> +	i2c_dev->msg = msgs;
> +	i2c_dev->msg_num = num;
> +	i2c_dev->msg_id = 0;
> +
> +	ret = clk_enable(i2c_dev->clk);
> +	if (ret) {
> +		dev_err(i2c_dev->dev, "Failed to enable clock\n");
> +		return ret;
> +	}
> +
> +	ret = stm32f7_i2c_wait_free_bus(i2c_dev);
> +	if (ret)
> +		goto clk_free;
> +
> +	stm32f7_i2c_xfer_msg(i2c_dev, msgs);
> +
> +	timeout = wait_for_completion_timeout(&i2c_dev->complete,
> +					      i2c_dev->adap.timeout);
> +	ret = f7_msg->result;
> +
> +	if (!timeout) {
> +		dev_dbg(i2c_dev->dev, "Access to slave 0x%x timed out\n",
> +			i2c_dev->msg->addr);
> +		ret = -ETIMEDOUT;
> +	}
> +
> +clk_free:
> +	clk_disable(i2c_dev->clk);
> +
> +	return (ret < 0) ? ret : num;
> +}
> +
> +static u32 stm32f7_i2c_func(struct i2c_adapter *adap)
> +{
> +	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> +}
> +
> +static struct i2c_algorithm stm32f7_i2c_algo = {
> +	.master_xfer = stm32f7_i2c_xfer,
> +	.functionality = stm32f7_i2c_func,
> +};
> +
> +static int stm32f7_i2c_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct stm32f7_i2c_dev *i2c_dev;
> +	struct resource *res;
> +	u32 irq_event, irq_error, clk_rate;
> +	struct i2c_adapter *adap;
> +	struct reset_control *rst;
> +	int ret;
> +
> +	i2c_dev = devm_kzalloc(&pdev->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(&pdev->dev, res);
> +	if (IS_ERR(i2c_dev->base))
> +		return PTR_ERR(i2c_dev->base);
> +
> +	irq_event = irq_of_parse_and_map(np, 0);
> +	if (!irq_event) {
> +		dev_err(&pdev->dev, "IRQ event missing or invalid\n");
> +		return -EINVAL;
> +	}
> +
> +	irq_error = irq_of_parse_and_map(np, 1);
> +	if (!irq_error) {
> +		dev_err(&pdev->dev, "IRQ error missing or invalid\n");
> +		return -EINVAL;
> +	}
> +
> +	i2c_dev->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(i2c_dev->clk)) {
> +		dev_err(&pdev->dev, "Error: Missing controller clock\n");
> +		return PTR_ERR(i2c_dev->clk);
> +	}
> +	ret = clk_prepare_enable(i2c_dev->clk);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to prepare_enable clock\n");
> +		return ret;
> +	}
> +
> +	rst = devm_reset_control_get(&pdev->dev, NULL);
> +	if (IS_ERR(rst)) {
> +		dev_err(&pdev->dev, "Error: Missing controller reset\n");
> +		ret = PTR_ERR(rst);
> +		goto clk_free;
> +	}
> +	reset_control_assert(rst);
> +	udelay(2);
> +	reset_control_deassert(rst);
> +
> +	i2c_dev->speed = STM32_I2C_SPEED_STANDARD;
> +	ret = of_property_read_u32(np, "clock-frequency", &clk_rate);
> +	if ((!ret) && (clk_rate == 400000))
> +		i2c_dev->speed = STM32_I2C_SPEED_FAST;
> +	else if ((!ret) && (clk_rate == 1000000))
> +		i2c_dev->speed = STM32_I2C_SPEED_FAST_PLUS;
> +
> +	i2c_dev->dev = &pdev->dev;
> +
> +	ret = devm_request_irq(&pdev->dev, irq_event, stm32f7_i2c_isr_event, 0,
> +			       pdev->name, i2c_dev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to request irq event %i\n",
> +			irq_event);
> +		goto clk_free;
> +	}
> +
> +	ret = devm_request_irq(&pdev->dev, irq_error, stm32f7_i2c_isr_error, 0,
> +			       pdev->name, i2c_dev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to request irq error %i\n",
> +			irq_error);
> +		goto clk_free;
> +	}
> +
> +	ret = stm32f7_i2c_hw_config(i2c_dev);
> +	if (ret)
> +		goto clk_free;
> +
> +	adap = &i2c_dev->adap;
> +	i2c_set_adapdata(adap, i2c_dev);
> +	snprintf(adap->name, sizeof(adap->name), "STM32F7 I2C(%pa)",
> +		 &res->start);
> +	adap->owner = THIS_MODULE;
> +	adap->timeout = 2 * HZ;
> +	adap->retries = 0;
> +	adap->algo = &stm32f7_i2c_algo;
> +	adap->dev.parent = &pdev->dev;
> +	adap->dev.of_node = pdev->dev.of_node;
> +
> +	init_completion(&i2c_dev->complete);
> +
> +	ret = i2c_add_adapter(adap);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to add adapter\n");
> +		goto clk_free;
> +	}
> +
> +	platform_set_drvdata(pdev, i2c_dev);
> +
> +	clk_disable(i2c_dev->clk);
> +
> +	dev_info(i2c_dev->dev, "STM32F7 I2C-%d driver registered\n", adap->nr);
> +
> +	return 0;
> +
> +clk_free:
> +	clk_disable_unprepare(i2c_dev->clk);
> +
> +	return ret;
> +}
> +
> +static int stm32f7_i2c_remove(struct platform_device *pdev)
> +{
> +	struct stm32f7_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
> +
> +	i2c_del_adapter(&i2c_dev->adap);
> +
> +	clk_unprepare(i2c_dev->clk);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id stm32f7_i2c_match[] = {
> +	{ .compatible = "st,stm32f7-i2c", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, stm32f7_i2c_match);
> +
> +static struct platform_driver stm32f7_i2c_driver = {
> +	.driver = {
> +		.name = "stm32f7-i2c",
> +		.of_match_table = stm32f7_i2c_match,
> +	},
> +	.probe = stm32f7_i2c_probe,
> +	.remove = stm32f7_i2c_remove,
> +};
> +
> +module_platform_driver(stm32f7_i2c_driver);
> +
> +MODULE_AUTHOR("M'boumba Cedric Madianga <cedric.madianga@...il.com>");
> +MODULE_DESCRIPTION("STMicroelectronics STM32F7 I2C driver");
> +MODULE_LICENSE("GPL v2");
> 

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