i2c: i2c-stm32f7: add driver

This patch adds initial support for the STM32F7 I2C controller.
Signed-off-by: NM'boumba Cedric Madianga <cedric.madianga@gmail.com>
Signed-off-by: NPierre-Yves MORDRET <pierre-yves.mordret@st.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/Kconfig

@@ -945,6 +945,16 @@ 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

drivers/i2c/busses/Makefile

@@ -94,6 +94,7 @@ obj-$(CONFIG_I2C_SIRF)		+= i2c-sirf.o
 obj-$(CONFIG_I2C_SPRD)		+= i2c-sprd.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

drivers/i2c/busses/i2c-stm32f7.c

+/*
+ * 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@gmail.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/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+#include <linux/slab.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_ANFOFF			BIT(12)
+#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)
+
+/* STM32F7 I2C Timing */
+#define STM32F7_I2C_TIMINGR_PRESC(n)		(((n) & 0xf) << 28)
+#define STM32F7_I2C_TIMINGR_SCLDEL(n)		(((n) & 0xf) << 20)
+#define STM32F7_I2C_TIMINGR_SDADEL(n)		(((n) & 0xf) << 16)
+#define STM32F7_I2C_TIMINGR_SCLH(n)		(((n) & 0xff) << 8)
+#define STM32F7_I2C_TIMINGR_SCLL(n)		((n) & 0xff)
+
+#define STM32F7_I2C_MAX_LEN			0xff
+
+#define STM32F7_I2C_DNF_DEFAULT			0
+#define STM32F7_I2C_DNF_MAX			16
+
+#define STM32F7_I2C_ANALOG_FILTER_ENABLE	1
+#define STM32F7_I2C_ANALOG_FILTER_DELAY_MIN	50	/* ns */
+#define STM32F7_I2C_ANALOG_FILTER_DELAY_MAX	260	/* ns */
+
+#define STM32F7_I2C_RISE_TIME_DEFAULT		25	/* ns */
+#define STM32F7_I2C_FALL_TIME_DEFAULT		10	/* ns */
+
+#define STM32F7_PRESC_MAX			BIT(4)
+#define STM32F7_SCLDEL_MAX			BIT(4)
+#define STM32F7_SDADEL_MAX			BIT(4)
+#define STM32F7_SCLH_MAX			BIT(8)
+#define STM32F7_SCLL_MAX			BIT(8)
+
+/**
+ * struct stm32f7_i2c_spec - private i2c specification timing
+ * @rate: I2C bus speed (Hz)
+ * @rate_min: 80% of I2C bus speed (Hz)
+ * @rate_max: 100% of I2C bus speed (Hz)
+ * @fall_max: Max fall time of both SDA and SCL signals (ns)
+ * @rise_max: Max rise time of both SDA and SCL signals (ns)
+ * @hddat_min: Min data hold time (ns)
+ * @vddat_max: Max data valid time (ns)
+ * @sudat_min: Min data setup time (ns)
+ * @l_min: Min low period of the SCL clock (ns)
+ * @h_min: Min high period of the SCL clock (ns)
+ */
+struct stm32f7_i2c_spec {
+	u32 rate;
+	u32 rate_min;
+	u32 rate_max;
+	u32 fall_max;
+	u32 rise_max;
+	u32 hddat_min;
+	u32 vddat_max;
+	u32 sudat_min;
+	u32 l_min;
+	u32 h_min;
+};
+
+/**
+ * struct stm32f7_i2c_setup - private I2C timing setup parameters
+ * @speed: I2C speed mode (standard, Fast Plus)
+ * @speed_freq: I2C speed frequency  (Hz)
+ * @clock_src: I2C clock source frequency (Hz)
+ * @rise_time: Rise time (ns)
+ * @fall_time: Fall time (ns)
+ * @dnf: Digital filter coefficient (0-16)
+ * @analog_filter: Analog filter delay (On/Off)
+ */
+struct stm32f7_i2c_setup {
+	enum stm32_i2c_speed speed;
+	u32 speed_freq;
+	u32 clock_src;
+	u32 rise_time;
+	u32 fall_time;
+	u8 dnf;
+	bool analog_filter;
+};
+
+/**
+ * struct stm32f7_i2c_timings - private I2C output parameters
+ * @prec: Prescaler value
+ * @scldel: Data setup time
+ * @sdadel: Data hold time
+ * @sclh: SCL high period (master mode)
+ * @sclh: SCL low period (master mode)
+ */
+struct stm32f7_i2c_timings {
+	struct list_head node;
+	u8 presc;
+	u8 scldel;
+	u8 sdadel;
+	u8 sclh;
+	u8 scll;
+};
+
+/**
+ * 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
+ * @setup: I2C timing input setup
+ * @timing: I2C computed timings
+ */
+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;
+	struct stm32f7_i2c_setup *setup;
+	struct stm32f7_i2c_timings timing;
+};
+
+/**
+ * All these values are coming from I2C Specification, Version 6.0, 4th of
+ * April 2014.
+ *
+ * Table10. Characteristics of the SDA and SCL bus lines for Standard, Fast,
+ * and Fast-mode Plus I2C-bus devices
+ */
+static struct stm32f7_i2c_spec i2c_specs[] = {
+	[STM32_I2C_SPEED_STANDARD] = {
+		.rate = 100000,
+		.rate_min = 80000,
+		.rate_max = 100000,
+		.fall_max = 300,
+		.rise_max = 1000,
+		.hddat_min = 0,
+		.vddat_max = 3450,
+		.sudat_min = 250,
+		.l_min = 4700,
+		.h_min = 4000,
+	},
+	[STM32_I2C_SPEED_FAST] = {
+		.rate = 400000,
+		.rate_min = 320000,
+		.rate_max = 400000,
+		.fall_max = 300,
+		.rise_max = 300,
+		.hddat_min = 0,
+		.vddat_max = 900,
+		.sudat_min = 100,
+		.l_min = 1300,
+		.h_min = 600,
+	},
+	[STM32_I2C_SPEED_FAST_PLUS] = {
+		.rate = 1000000,
+		.rate_min = 800000,
+		.rate_max = 1000000,
+		.fall_max = 100,
+		.rise_max = 120,
+		.hddat_min = 0,
+		.vddat_max = 450,
+		.sudat_min = 50,
+		.l_min = 500,
+		.h_min = 260,
+	},
+};
+
+struct stm32f7_i2c_setup stm32f7_setup = {
+	.rise_time = STM32F7_I2C_RISE_TIME_DEFAULT,
+	.fall_time = STM32F7_I2C_FALL_TIME_DEFAULT,
+	.dnf = STM32F7_I2C_DNF_DEFAULT,
+	.analog_filter = STM32F7_I2C_ANALOG_FILTER_ENABLE,
+};
+
+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_compute_timing(struct stm32f7_i2c_dev *i2c_dev,
+				      struct stm32f7_i2c_setup *setup,
+				      struct stm32f7_i2c_timings *output)
+{
+	u32 p_prev = STM32F7_PRESC_MAX;
+	u32 i2cclk = DIV_ROUND_CLOSEST(NSEC_PER_SEC,
+				       setup->clock_src);
+	u32 i2cbus = DIV_ROUND_CLOSEST(NSEC_PER_SEC,
+				       setup->speed_freq);
+	u32 clk_error_prev = i2cbus;
+	u32 tsync;
+	u32 af_delay_min, af_delay_max;
+	u32 dnf_delay;
+	u32 clk_min, clk_max;
+	int sdadel_min, sdadel_max;
+	int scldel_min;
+	struct stm32f7_i2c_timings *v, *_v, *s;
+	struct list_head solutions;
+	u16 p, l, a, h;
+	int ret = 0;
+
+	if (setup->speed >= STM32_I2C_SPEED_END) {
+		dev_err(i2c_dev->dev, "speed out of bound {%d/%d}\n",
+			setup->speed, STM32_I2C_SPEED_END - 1);
+		return -EINVAL;
+	}
+
+	if ((setup->rise_time > i2c_specs[setup->speed].rise_max) ||
+	    (setup->fall_time > i2c_specs[setup->speed].fall_max)) {
+		dev_err(i2c_dev->dev,
+			"timings out of bound Rise{%d>%d}/Fall{%d>%d}\n",
+			setup->rise_time, i2c_specs[setup->speed].rise_max,
+			setup->fall_time, i2c_specs[setup->speed].fall_max);
+		return -EINVAL;
+	}
+
+	if (setup->dnf > STM32F7_I2C_DNF_MAX) {
+		dev_err(i2c_dev->dev,
+			"DNF out of bound %d/%d\n",
+			setup->dnf, STM32F7_I2C_DNF_MAX);
+		return -EINVAL;
+	}
+
+	if (setup->speed_freq > i2c_specs[setup->speed].rate) {
+		dev_err(i2c_dev->dev, "ERROR: Freq {%d/%d}\n",
+			setup->speed_freq, i2c_specs[setup->speed].rate);
+		return -EINVAL;
+	}
+
+	/*  Analog and Digital Filters */
+	af_delay_min =
+		(setup->analog_filter ?
+		 STM32F7_I2C_ANALOG_FILTER_DELAY_MIN : 0);
+	af_delay_max =
+		(setup->analog_filter ?
+		 STM32F7_I2C_ANALOG_FILTER_DELAY_MAX : 0);
+	dnf_delay = setup->dnf * i2cclk;
+
+	sdadel_min = setup->fall_time - i2c_specs[setup->speed].hddat_min -
+		af_delay_min - (setup->dnf + 3) * i2cclk;
+
+	sdadel_max = i2c_specs[setup->speed].vddat_max - setup->rise_time -
+		af_delay_max - (setup->dnf + 4) * i2cclk;
+
+	scldel_min = setup->rise_time + i2c_specs[setup->speed].sudat_min;
+
+	if (sdadel_min < 0)
+		sdadel_min = 0;
+	if (sdadel_max < 0)
+		sdadel_max = 0;
+
+	dev_dbg(i2c_dev->dev, "SDADEL(min/max): %i/%i, SCLDEL(Min): %i\n",
+		sdadel_min, sdadel_max, scldel_min);
+
+	INIT_LIST_HEAD(&solutions);
+	/* Compute possible values for PRESC, SCLDEL and SDADEL */
+	for (p = 0; p < STM32F7_PRESC_MAX; p++) {
+		for (l = 0; l < STM32F7_SCLDEL_MAX; l++) {
+			u32 scldel = (l + 1) * (p + 1) * i2cclk;
+
+			if (scldel < scldel_min)
+				continue;
+
+			for (a = 0; a < STM32F7_SDADEL_MAX; a++) {
+				u32 sdadel = (a * (p + 1) + 1) * i2cclk;
+
+				if (((sdadel >= sdadel_min) &&
+				     (sdadel <= sdadel_max)) &&
+				    (p != p_prev)) {
+					v = kmalloc(sizeof(*v), GFP_KERNEL);
+					if (!v) {
+						ret = -ENOMEM;
+						goto exit;
+					}
+
+					v->presc = p;
+					v->scldel = l;
+					v->sdadel = a;
+					p_prev = p;
+
+					list_add_tail(&v->node,
+						      &solutions);
+				}
+			}
+		}
+	}
+
+	if (list_empty(&solutions)) {
+		dev_err(i2c_dev->dev, "no Prescaler solution\n");
+		ret = -EPERM;
+		goto exit;
+	}
+
+	tsync = af_delay_min + dnf_delay + (2 * i2cclk);
+	s = NULL;
+	clk_max = NSEC_PER_SEC / i2c_specs[setup->speed].rate_min;
+	clk_min = NSEC_PER_SEC / i2c_specs[setup->speed].rate_max;
+
+	/*
+	 * Among Prescaler possibilities discovered above figures out SCL Low
+	 * and High Period. Provided:
+	 * - SCL Low Period has to be higher than SCL Clock Low Period
+	 *   defined by I2C Specification. I2C Clock has to be lower than
+	 *   (SCL Low Period - Analog/Digital filters) / 4.
+	 * - SCL High Period has to be lower than SCL Clock High Period
+	 *   defined by I2C Specification
+	 * - I2C Clock has to be lower than SCL High Period
+	 */
+	list_for_each_entry(v, &solutions, node) {
+		u32 prescaler = (v->presc + 1) * i2cclk;
+
+		for (l = 0; l < STM32F7_SCLL_MAX; l++) {
+			u32 tscl_l = (l + 1) * prescaler + tsync;
+
+			if ((tscl_l < i2c_specs[setup->speed].l_min) ||
+			    (i2cclk >=
+			     ((tscl_l - af_delay_min - dnf_delay) / 4))) {
+				continue;
+			}
+
+			for (h = 0; h < STM32F7_SCLH_MAX; h++) {
+				u32 tscl_h = (h + 1) * prescaler + tsync;
+				u32 tscl = tscl_l + tscl_h +
+					setup->rise_time + setup->fall_time;
+
+				if ((tscl >= clk_min) && (tscl <= clk_max) &&
+				    (tscl_h >= i2c_specs[setup->speed].h_min) &&
+				    (i2cclk < tscl_h)) {
+					int clk_error = tscl - i2cbus;
+
+					if (clk_error < 0)
+						clk_error = -clk_error;
+
+					if (clk_error < clk_error_prev) {
+						clk_error_prev = clk_error;
+						v->scll = l;
+						v->sclh = h;
+						s = v;
+					}
+				}
+			}
+		}
+	}
+
+	if (!s) {
+		dev_err(i2c_dev->dev, "no solution at all\n");
+		ret = -EPERM;
+		goto exit;
+	}
+
+	output->presc = s->presc;
+	output->scldel = s->scldel;
+	output->sdadel = s->sdadel;
+	output->scll = s->scll;
+	output->sclh = s->sclh;
+
+	dev_dbg(i2c_dev->dev,
+		"Presc: %i, scldel: %i, sdadel: %i, scll: %i, sclh: %i\n",
+		output->presc,
+		output->scldel, output->sdadel,
+		output->scll, output->sclh);
+
+exit:
+	/* Release list and memory */
+	list_for_each_entry_safe(v, _v, &solutions, node) {
+		list_del(&v->node);
+		kfree(v);
+	}
+
+	return ret;
+}
+
+static int stm32f7_i2c_setup_timing(struct stm32f7_i2c_dev *i2c_dev,
+				    struct stm32f7_i2c_setup *setup)
+{
+	int ret = 0;
+
+	setup->speed = i2c_dev->speed;
+	setup->speed_freq = i2c_specs[setup->speed].rate;
+	setup->clock_src = clk_get_rate(i2c_dev->clk);
+
+	if (!setup->clock_src) {
+		dev_err(i2c_dev->dev, "clock rate is 0\n");
+		return -EINVAL;
+	}
+
+	do {
+		ret = stm32f7_i2c_compute_timing(i2c_dev, setup,
+						 &i2c_dev->timing);
+		if (ret) {
+			dev_err(i2c_dev->dev,
+				"failed to compute I2C timings.\n");
+			if (i2c_dev->speed > STM32_I2C_SPEED_STANDARD) {
+				i2c_dev->speed--;
+				setup->speed = i2c_dev->speed;
+				setup->speed_freq =
+					i2c_specs[setup->speed].rate;
+				dev_warn(i2c_dev->dev,
+					 "downgrade I2C Speed Freq to (%i)\n",
+					 i2c_specs[setup->speed].rate);
+			} else {
+				break;
+			}
+		}
+	} while (ret);
+
+	if (ret) {
+		dev_err(i2c_dev->dev, "Impossible to compute I2C timings.\n");
+		return ret;
+	}
+
+	dev_dbg(i2c_dev->dev, "I2C Speed(%i), Freq(%i), Clk Source(%i)\n",
+		setup->speed, setup->speed_freq, setup->clock_src);
+	dev_dbg(i2c_dev->dev, "I2C Rise(%i) and Fall(%i) Time\n",
+		setup->rise_time, setup->fall_time);
+	dev_dbg(i2c_dev->dev, "I2C Analog Filter(%s), DNF(%i)\n",
+		(setup->analog_filter ? "On" : "Off"), setup->dnf);
+
+	return 0;
+}
+
+static void stm32f7_i2c_hw_config(struct stm32f7_i2c_dev *i2c_dev)
+{
+	struct stm32f7_i2c_timings *t = &i2c_dev->timing;
+	u32 timing = 0;
+
+	/* Timing settings */
+	timing |= STM32F7_I2C_TIMINGR_PRESC(t->presc);
+	timing |= STM32F7_I2C_TIMINGR_SCLDEL(t->scldel);
+	timing |= STM32F7_I2C_TIMINGR_SDADEL(t->sdadel);
+	timing |= STM32F7_I2C_TIMINGR_SCLH(t->sclh);
+	timing |= STM32F7_I2C_TIMINGR_SCLL(t->scll);
+	writel_relaxed(timing, i2c_dev->base + STM32F7_I2C_TIMINGR);
+
+	/* Enable I2C */
+	if (i2c_dev->setup->analog_filter)
+		stm32f7_i2c_clr_bits(i2c_dev->base + STM32F7_I2C_CR1,
+				     STM32F7_I2C_CR1_ANFOFF);
+	else
+		stm32f7_i2c_set_bits(i2c_dev->base + STM32F7_I2C_CR1,
+				     STM32F7_I2C_CR1_ANFOFF);
+	stm32f7_i2c_set_bits(i2c_dev->base + STM32F7_I2C_CR1,
+			     STM32F7_I2C_CR1_PE);
+}
+
+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 = -ENXIO;
+	}
+
+	/* 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_dbg(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 time_left;
+	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);
+
+	time_left = wait_for_completion_timeout(&i2c_dev->complete,
+						i2c_dev->adap.timeout);
+	ret = f7_msg->result;
+
+	if (!time_left) {
+		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;
+	const struct stm32f7_i2c_setup *setup;
+	struct resource *res;
+	u32 irq_error, irq_event, clk_rate, rise_time, fall_time;
+	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;
+	}
+
+	i2c_dev->speed = STM32_I2C_SPEED_STANDARD;
+	ret = device_property_read_u32(&pdev->dev, "clock-frequency",
+				       &clk_rate);
+	if (!ret && clk_rate >= 1000000)
+		i2c_dev->speed = STM32_I2C_SPEED_FAST_PLUS;
+	else if (!ret && clk_rate >= 400000)
+		i2c_dev->speed = STM32_I2C_SPEED_FAST;
+	else if (!ret && clk_rate >= 100000)
+		i2c_dev->speed = STM32_I2C_SPEED_STANDARD;
+
+	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->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;
+	}
+
+	setup = of_device_get_match_data(&pdev->dev);
+	i2c_dev->setup->rise_time = setup->rise_time;
+	i2c_dev->setup->fall_time = setup->fall_time;
+	i2c_dev->setup->dnf = setup->dnf;
+	i2c_dev->setup->analog_filter = setup->analog_filter;
+
+	ret = device_property_read_u32(i2c_dev->dev, "i2c-scl-rising-time-ns",
+				       &rise_time);
+	if (!ret)
+		i2c_dev->setup->rise_time = rise_time;
+
+	ret = device_property_read_u32(i2c_dev->dev, "i2c-scl-falling-time-ns",
+				       &fall_time);
+	if (!ret)
+		i2c_dev->setup->fall_time = fall_time;
+
+	ret = stm32f7_i2c_setup_timing(i2c_dev, i2c_dev->setup);
+	if (ret)
+		goto clk_free;
+
+	stm32f7_i2c_hw_config(i2c_dev);
+
+	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 = 3;
+	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)
+		goto clk_free;
+
+	platform_set_drvdata(pdev, i2c_dev);
+
+	clk_disable(i2c_dev->clk);
+
+	dev_info(i2c_dev->dev, "STM32F7 I2C-%d bus adapter\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", .data = &stm32f7_setup},
+	{},
+};
+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@gmail.com>");
+MODULE_DESCRIPTION("STMicroelectronics STM32F7 I2C driver");
+MODULE_LICENSE("GPL v2");