[RESEND PATCH v1 0/6] Add different features for I2C

[RESEND PATCH v1 0/6] Add different features for I2C

[Pierre-Yves MORDRET]

Append new I2C STM32F7 feature set. This includes 10 bit support, slave
support, SMBBus protocols support, DMA Support and eventually an I2C recovery
mechanism

---
  Version history:
    v1:
        * Initial
---
Pierre-Yves MORDRET (6):
  i2c: i2c-stm32f7: Add 10-bit address support
  i2c: i2c-stm32f7: Add slave support
  i2c: i2c-stm32f7: Add initial SMBus protocols support
  i2c: i2c-stm32: Add generic DMA API
  i2c: i2c-stm32f7: Add DMA support
  i2c: i2c-stm32f7: Implement I2C recovery mechanism

 drivers/i2c/busses/Kconfig       |    1 +
 drivers/i2c/busses/Makefile      |    3 +-
 drivers/i2c/busses/i2c-stm32.c   |  153 ++++++
 drivers/i2c/busses/i2c-stm32.h   |   37 ++
 drivers/i2c/busses/i2c-stm32f7.c | 1047 +++++++++++++++++++++++++++++++++++++-
 5 files changed, 1214 insertions(+), 27 deletions(-)
 create mode 100644 drivers/i2c/busses/i2c-stm32.c

-- 
2.7.4

[RESEND PATCH v1 1/6] i2c: i2c-stm32f7: Add 10-bit address support

[Pierre-Yves MORDRET]

This patch adds support for 10-bit device address for STM32F7 I2C

Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
---
  Version history:
     v1:
        * Initial
---
---
 drivers/i2c/busses/i2c-stm32f7.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index 16c7d77..31bfa00 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -65,7 +65,12 @@
 #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_HEAD10R			BIT(12)
+#define STM32F7_I2C_CR2_ADD10			BIT(11)
 #define STM32F7_I2C_CR2_RD_WRN			BIT(10)
+#define STM32F7_I2C_CR2_SADD10_MASK		GENMASK(9, 0)
+#define STM32F7_I2C_CR2_SADD10(n)		(((n) & \
+						STM32F7_I2C_CR2_SADD10_MASK))
 #define STM32F7_I2C_CR2_SADD7_MASK		GENMASK(7, 1)
 #define STM32F7_I2C_CR2_SADD7(n)		(((n) & 0x7f) << 1)
 
@@ -176,14 +181,14 @@ struct stm32f7_i2c_timings {
 
 /**
  * struct stm32f7_i2c_msg - client specific data
- * @addr: 8-bit slave addr, including r/w bit
+ * @addr: 8-bit or 10-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;
+	u16 addr;
 	u32 count;
 	u8 *buf;
 	int result;
@@ -629,8 +634,15 @@ static void stm32f7_i2c_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
 		cr2 |= STM32F7_I2C_CR2_RD_WRN;
 
 	/* Set slave address */
-	cr2 &= ~STM32F7_I2C_CR2_SADD7_MASK;
-	cr2 |= STM32F7_I2C_CR2_SADD7(f7_msg->addr);
+	cr2 &= ~(STM32F7_I2C_CR2_HEAD10R | STM32F7_I2C_CR2_ADD10);
+	if (msg->flags & I2C_M_TEN) {
+		cr2 &= ~STM32F7_I2C_CR2_SADD10_MASK;
+		cr2 |= STM32F7_I2C_CR2_SADD10(f7_msg->addr);
+		cr2 |= STM32F7_I2C_CR2_ADD10;
+	} else {
+		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);
@@ -798,7 +810,7 @@ static int stm32f7_i2c_xfer(struct i2c_adapter *i2c_adap,
 
 static u32 stm32f7_i2c_func(struct i2c_adapter *adap)
 {
-	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR;
 }
 
 static struct i2c_algorithm stm32f7_i2c_algo = {
-- 
2.7.4

[RESEND PATCH v1 2/6] i2c: i2c-stm32f7: Add slave support

[Pierre-Yves MORDRET]

This patch adds slave support for I2C controller embedded in STM32F7 SoC

Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
---
  Version history:
     v1:
        * Initial
---
---
 drivers/i2c/busses/Kconfig       |   1 +
 drivers/i2c/busses/i2c-stm32f7.c | 434 ++++++++++++++++++++++++++++++++++++++-
 2 files changed, 429 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index a9805c7..08f1490 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -962,6 +962,7 @@ config I2C_STM32F4
 config I2C_STM32F7
 	tristate "STMicroelectronics STM32F7 I2C support"
 	depends on ARCH_STM32 || COMPILE_TEST
+	select I2C_SLAVE
 	help
 	  Enable this option to add support for STM32 I2C controller embedded
 	  in STM32F7 SoCs.
diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index 31bfa00..aff1750 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -35,6 +35,8 @@
 /* STM32F7 I2C registers */
 #define STM32F7_I2C_CR1				0x00
 #define STM32F7_I2C_CR2				0x04
+#define STM32F7_I2C_OAR1			0x08
+#define STM32F7_I2C_OAR2			0x0C
 #define STM32F7_I2C_TIMINGR			0x10
 #define STM32F7_I2C_ISR				0x18
 #define STM32F7_I2C_ICR				0x1C
@@ -42,6 +44,7 @@
 #define STM32F7_I2C_TXDR			0x28
 
 /* STM32F7 I2C control 1 */
+#define STM32F7_I2C_CR1_SBC			BIT(16)
 #define STM32F7_I2C_CR1_ANFOFF			BIT(12)
 #define STM32F7_I2C_CR1_ERRIE			BIT(7)
 #define STM32F7_I2C_CR1_TCIE			BIT(6)
@@ -57,6 +60,11 @@
 						| STM32F7_I2C_CR1_NACKIE \
 						| STM32F7_I2C_CR1_RXIE \
 						| STM32F7_I2C_CR1_TXIE)
+#define STM32F7_I2C_XFER_IRQ_MASK		(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)
@@ -74,7 +82,34 @@
 #define STM32F7_I2C_CR2_SADD7_MASK		GENMASK(7, 1)
 #define STM32F7_I2C_CR2_SADD7(n)		(((n) & 0x7f) << 1)
 
+/* STM32F7 I2C Own Address 1 */
+#define STM32F7_I2C_OAR1_OA1EN			BIT(15)
+#define STM32F7_I2C_OAR1_OA1MODE		BIT(10)
+#define STM32F7_I2C_OAR1_OA1_10_MASK		GENMASK(9, 0)
+#define STM32F7_I2C_OAR1_OA1_10(n)		(((n) & \
+						STM32F7_I2C_OAR1_OA1_10_MASK))
+#define STM32F7_I2C_OAR1_OA1_7_MASK		GENMASK(7, 1)
+#define STM32F7_I2C_OAR1_OA1_7(n)		(((n) & 0x7f) << 1)
+#define STM32F7_I2C_OAR1_MASK			(STM32F7_I2C_OAR1_OA1_7_MASK \
+						| STM32F7_I2C_OAR1_OA1_10_MASK \
+						| STM32F7_I2C_OAR1_OA1EN \
+						| STM32F7_I2C_OAR1_OA1MODE)
+
+/* STM32F7 I2C Own Address 2 */
+#define STM32F7_I2C_OAR2_OA2EN			BIT(15)
+#define STM32F7_I2C_OAR2_OA2MSK_MASK		GENMASK(10, 8)
+#define STM32F7_I2C_OAR2_OA2MSK(n)		(((n) & 0x7) << 8)
+#define STM32F7_I2C_OAR2_OA2_7_MASK		GENMASK(7, 1)
+#define STM32F7_I2C_OAR2_OA2_7(n)		(((n) & 0x7f) << 1)
+#define STM32F7_I2C_OAR2_MASK			(STM32F7_I2C_OAR2_OA2MSK_MASK \
+						| STM32F7_I2C_OAR2_OA2_7_MASK \
+						| STM32F7_I2C_OAR2_OA2EN)
+
 /* STM32F7 I2C Interrupt Status */
+#define STM32F7_I2C_ISR_ADDCODE_MASK		GENMASK(23, 17)
+#define STM32F7_I2C_ISR_ADDCODE_GET(n) \
+				(((n) & STM32F7_I2C_ISR_ADDCODE_MASK) >> 17)
+#define STM32F7_I2C_ISR_DIR			BIT(16)
 #define STM32F7_I2C_ISR_BUSY			BIT(15)
 #define STM32F7_I2C_ISR_ARLO			BIT(9)
 #define STM32F7_I2C_ISR_BERR			BIT(8)
@@ -82,14 +117,17 @@
 #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_ADDR			BIT(3)
 #define STM32F7_I2C_ISR_RXNE			BIT(2)
 #define STM32F7_I2C_ISR_TXIS			BIT(1)
+#define STM32F7_I2C_ISR_TXE			BIT(0)
 
 /* 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_ICR_ADDRCF			BIT(3)
 
 /* STM32F7 I2C Timing */
 #define STM32F7_I2C_TIMINGR_PRESC(n)		(((n) & 0xf) << 28)
@@ -99,6 +137,7 @@
 #define STM32F7_I2C_TIMINGR_SCLL(n)		((n) & 0xff)
 
 #define STM32F7_I2C_MAX_LEN			0xff
+#define STM32F7_I2C_MAX_SLAVE			0x2
 
 #define STM32F7_I2C_DNF_DEFAULT			0
 #define STM32F7_I2C_DNF_MAX			16
@@ -209,6 +248,11 @@ struct stm32f7_i2c_msg {
  * @f7_msg: customized i2c msg for driver usage
  * @setup: I2C timing input setup
  * @timing: I2C computed timings
+ * @slave: list of slave devices registered on the I2C bus
+ * @slave_running: slave device currently used
+ * @slave_dir: transfer direction for the current slave device
+ * @master_mode: boolean to know in which mode the I2C is running (master or
+ * slave)
  */
 struct stm32f7_i2c_dev {
 	struct i2c_adapter adap;
@@ -223,6 +267,10 @@ struct stm32f7_i2c_dev {
 	struct stm32f7_i2c_msg f7_msg;
 	struct stm32f7_i2c_setup setup;
 	struct stm32f7_i2c_timings timing;
+	struct i2c_client *slave[STM32F7_I2C_MAX_SLAVE];
+	struct i2c_client *slave_running;
+	u32 slave_dir;
+	bool master_mode;
 };
 
 /**
@@ -288,6 +336,11 @@ static inline void stm32f7_i2c_clr_bits(void __iomem *reg, u32 mask)
 	writel_relaxed(readl_relaxed(reg) & ~mask, reg);
 }
 
+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 int stm32f7_i2c_compute_timing(struct stm32f7_i2c_dev *i2c_dev,
 				      struct stm32f7_i2c_setup *setup,
 				      struct stm32f7_i2c_timings *output)
@@ -572,6 +625,9 @@ static void stm32f7_i2c_read_rx_data(struct stm32f7_i2c_dev *i2c_dev)
 	if (f7_msg->count) {
 		*f7_msg->buf++ = readb_relaxed(base + STM32F7_I2C_RXDR);
 		f7_msg->count--;
+	} else {
+		/* Flush RX buffer has no data is expected */
+		readb_relaxed(base + STM32F7_I2C_RXDR);
 	}
 }
 
@@ -669,14 +725,250 @@ static void stm32f7_i2c_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
 	/* Configure Start/Repeated Start */
 	cr2 |= STM32F7_I2C_CR2_START;
 
+	i2c_dev->master_mode = true;
+
 	/* 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)
+static bool stm32f7_i2c_is_addr_match(struct i2c_client *slave, u32 addcode)
 {
-	stm32f7_i2c_clr_bits(i2c_dev->base + STM32F7_I2C_CR1, mask);
+	u32 addr;
+
+	if (!slave)
+		return false;
+
+	if (slave->flags & I2C_CLIENT_TEN) {
+		/*
+		 * For 10-bit addr, addcode = 11110XY with
+		 * X = Bit 9 of slave address
+		 * Y = Bit 8 of slave address
+		 */
+		addr = slave->addr >> 8;
+		addr |= 0x78;
+		if (addr == addcode)
+			return true;
+	} else {
+		addr = slave->addr & 0x7f;
+		if (addr == addcode)
+			return true;
+	}
+
+	return false;
+}
+
+static void stm32f7_i2c_slave_start(struct stm32f7_i2c_dev *i2c_dev)
+{
+	struct i2c_client *slave = i2c_dev->slave_running;
+	void __iomem *base = i2c_dev->base;
+	u32 mask;
+	u8 value = 0;
+
+	if (i2c_dev->slave_dir) {
+		/* Notify i2c slave that new read transfer is starting */
+		i2c_slave_event(slave, I2C_SLAVE_READ_REQUESTED, &value);
+
+		/*
+		 * Disable slave TX config in case of I2C combined message
+		 * (I2C Write followed by I2C Read)
+		 */
+		mask = STM32F7_I2C_CR2_RELOAD;
+		stm32f7_i2c_clr_bits(base + STM32F7_I2C_CR2, mask);
+		mask = STM32F7_I2C_CR1_SBC | STM32F7_I2C_CR1_RXIE |
+		       STM32F7_I2C_CR1_TCIE;
+		stm32f7_i2c_clr_bits(base + STM32F7_I2C_CR1, mask);
+
+		/* Enable TX empty, STOP, NACK interrupts */
+		mask =  STM32F7_I2C_CR1_STOPIE | STM32F7_I2C_CR1_NACKIE |
+			STM32F7_I2C_CR1_TXIE;
+		stm32f7_i2c_set_bits(base + STM32F7_I2C_CR1, mask);
+
+	} else {
+		/* Notify i2c slave that new write transfer is starting */
+		i2c_slave_event(slave, I2C_SLAVE_WRITE_REQUESTED, &value);
+
+		/* Set reload mode to be able to ACK/NACK each received byte */
+		mask = STM32F7_I2C_CR2_RELOAD;
+		stm32f7_i2c_set_bits(base + STM32F7_I2C_CR2, mask);
+
+		/*
+		 * Set STOP, NACK, RX empty and transfer complete interrupts.*
+		 * Set Slave Byte Control to be able to ACK/NACK each data
+		 * byte received
+		 */
+		mask =  STM32F7_I2C_CR1_STOPIE | STM32F7_I2C_CR1_NACKIE |
+			STM32F7_I2C_CR1_SBC | STM32F7_I2C_CR1_RXIE |
+			STM32F7_I2C_CR1_TCIE;
+		stm32f7_i2c_set_bits(base + STM32F7_I2C_CR1, mask);
+	}
+}
+
+static void stm32f7_i2c_slave_addr(struct stm32f7_i2c_dev *i2c_dev)
+{
+	void __iomem *base = i2c_dev->base;
+	u32 isr, addcode, dir, mask;
+	int i;
+
+	isr = readl_relaxed(i2c_dev->base + STM32F7_I2C_ISR);
+	addcode = STM32F7_I2C_ISR_ADDCODE_GET(isr);
+	dir = isr & STM32F7_I2C_ISR_DIR;
+
+	for (i = 0; i < STM32F7_I2C_MAX_SLAVE; i++) {
+		if (stm32f7_i2c_is_addr_match(i2c_dev->slave[i], addcode)) {
+			i2c_dev->slave_running = i2c_dev->slave[i];
+			i2c_dev->slave_dir = dir;
+
+			/* Start I2C slave processing */
+			stm32f7_i2c_slave_start(i2c_dev);
+
+			/* Clear ADDR flag */
+			mask = STM32F7_I2C_ICR_ADDRCF;
+			writel_relaxed(mask, base + STM32F7_I2C_ICR);
+			break;
+		}
+	}
+}
+
+static int stm32f7_i2c_get_slave_id(struct stm32f7_i2c_dev *i2c_dev,
+				    struct i2c_client *slave, int *id)
+{
+	int i;
+
+	for (i = 0; i < STM32F7_I2C_MAX_SLAVE; i++) {
+		if (i2c_dev->slave[i] == slave) {
+			*id = i;
+			return 0;
+		}
+	}
+
+	dev_err(i2c_dev->dev, "Slave 0x%x not registered\n", slave->addr);
+
+	return -ENODEV;
+}
+
+static int stm32f7_i2c_get_free_slave_id(struct stm32f7_i2c_dev *i2c_dev,
+					 struct i2c_client *slave, int *id)
+{
+	struct device *dev = i2c_dev->dev;
+	int i;
+
+	/*
+	 * slave[0] supports 7-bit and 10-bit slave address
+	 * slave[1] supports 7-bit slave address only
+	 */
+	for (i = 0; i < STM32F7_I2C_MAX_SLAVE; i++) {
+		if (i == 1 && (slave->flags & I2C_CLIENT_PEC))
+			continue;
+		if (!i2c_dev->slave[i]) {
+			*id = i;
+			return 0;
+		}
+	}
+
+	dev_err(dev, "Slave 0x%x could not be registered\n", slave->addr);
+
+	return -EINVAL;
+}
+
+static bool stm32f7_i2c_is_slave_registered(struct stm32f7_i2c_dev *i2c_dev)
+{
+	int i;
+
+	for (i = 0; i < STM32F7_I2C_MAX_SLAVE; i++) {
+		if (i2c_dev->slave[i])
+			return true;
+	}
+
+	return false;
+}
+
+static bool stm32f7_i2c_is_slave_busy(struct stm32f7_i2c_dev *i2c_dev)
+{
+	int i, busy;
+
+	busy = 0;
+	for (i = 0; i < STM32F7_I2C_MAX_SLAVE; i++) {
+		if (i2c_dev->slave[i])
+			busy++;
+	}
+
+	return i == busy;
+}
+
+static irqreturn_t stm32f7_i2c_slave_isr_event(struct stm32f7_i2c_dev *i2c_dev)
+{
+	void __iomem *base = i2c_dev->base;
+	u32 cr2, status, mask;
+	u8 val;
+	int ret;
+
+	status = readl_relaxed(i2c_dev->base + STM32F7_I2C_ISR);
+
+	/* Slave transmitter mode */
+	if (status & STM32F7_I2C_ISR_TXIS) {
+		i2c_slave_event(i2c_dev->slave_running,
+				I2C_SLAVE_READ_PROCESSED,
+				&val);
+
+		/* Write data byte */
+		writel_relaxed(val, base + STM32F7_I2C_TXDR);
+	}
+
+	/* Transfer Complete Reload for Slave receiver mode */
+	if (status & STM32F7_I2C_ISR_TCR || status & STM32F7_I2C_ISR_RXNE) {
+		/*
+		 * Read data byte then set NBYTES to receive next byte or NACK
+		 * the current received byte
+		 */
+		val = readb_relaxed(i2c_dev->base + STM32F7_I2C_RXDR);
+		ret = i2c_slave_event(i2c_dev->slave_running,
+				      I2C_SLAVE_WRITE_RECEIVED,
+				      &val);
+		if (!ret) {
+			cr2 = readl_relaxed(i2c_dev->base + STM32F7_I2C_CR2);
+			cr2 |= STM32F7_I2C_CR2_NBYTES(1);
+			writel_relaxed(cr2, i2c_dev->base + STM32F7_I2C_CR2);
+		} else {
+			mask = STM32F7_I2C_CR2_NACK;
+			stm32f7_i2c_set_bits(base + STM32F7_I2C_CR2, mask);
+		}
+	}
+
+	/* 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);
+	}
+
+	/* STOP received */
+	if (status & STM32F7_I2C_ISR_STOPF) {
+		/* Disable interrupts */
+		stm32f7_i2c_disable_irq(i2c_dev, STM32F7_I2C_XFER_IRQ_MASK);
+
+		if (i2c_dev->slave_dir) {
+			/*
+			 * Flush TX buffer in order to not used the byte in
+			 * TXDR for the next transfer
+			 */
+			mask = STM32F7_I2C_ISR_TXE;
+			stm32f7_i2c_set_bits(base + STM32F7_I2C_ISR, mask);
+		}
+
+		/* Clear STOP flag */
+		writel_relaxed(STM32F7_I2C_ICR_STOPCF, base + STM32F7_I2C_ICR);
+
+		/* Notify i2c slave that a STOP flag has been detected */
+		i2c_slave_event(i2c_dev->slave_running, I2C_SLAVE_STOP, &val);
+
+		i2c_dev->slave_running = NULL;
+	}
+
+	/* Address match received */
+	if (status & STM32F7_I2C_ISR_ADDR)
+		stm32f7_i2c_slave_addr(i2c_dev);
+
+	return IRQ_HANDLED;
 }
 
 static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
@@ -685,6 +977,13 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
 	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
 	void __iomem *base = i2c_dev->base;
 	u32 status, mask;
+	int ret;
+
+	/* Check if the interrupt if for a slave device */
+	if (!i2c_dev->master_mode) {
+		ret = stm32f7_i2c_slave_isr_event(i2c_dev);
+		return ret;
+	}
 
 	status = readl_relaxed(i2c_dev->base + STM32F7_I2C_ISR);
 
@@ -706,11 +1005,16 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
 	/* STOP detection flag */
 	if (status & STM32F7_I2C_ISR_STOPF) {
 		/* Disable interrupts */
-		stm32f7_i2c_disable_irq(i2c_dev, STM32F7_I2C_ALL_IRQ_MASK);
+		if (stm32f7_i2c_is_slave_registered(i2c_dev))
+			mask = STM32F7_I2C_XFER_IRQ_MASK;
+		else
+			mask = STM32F7_I2C_ALL_IRQ_MASK;
+		stm32f7_i2c_disable_irq(i2c_dev, mask);
 
 		/* Clear STOP flag */
 		writel_relaxed(STM32F7_I2C_ICR_STOPCF, base + STM32F7_I2C_ICR);
 
+		i2c_dev->master_mode = false;
 		complete(&i2c_dev->complete);
 	}
 
@@ -743,7 +1047,7 @@ static irqreturn_t stm32f7_i2c_isr_error(int irq, void *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;
+	u32 mask, status;
 
 	status = readl_relaxed(i2c_dev->base + STM32F7_I2C_ISR);
 
@@ -761,8 +1065,14 @@ static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
 		f7_msg->result = -EAGAIN;
 	}
 
-	stm32f7_i2c_disable_irq(i2c_dev, STM32F7_I2C_ALL_IRQ_MASK);
+	/* Disable interrupts */
+	if (stm32f7_i2c_is_slave_registered(i2c_dev))
+		mask = STM32F7_I2C_XFER_IRQ_MASK;
+	else
+		mask = STM32F7_I2C_ALL_IRQ_MASK;
+	stm32f7_i2c_disable_irq(i2c_dev, mask);
 
+	i2c_dev->master_mode = false;
 	complete(&i2c_dev->complete);
 
 	return IRQ_HANDLED;
@@ -808,14 +1118,126 @@ static int stm32f7_i2c_xfer(struct i2c_adapter *i2c_adap,
 	return (ret < 0) ? ret : num;
 }
 
+static int stm32f7_i2c_reg_slave(struct i2c_client *slave)
+{
+	struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(slave->adapter);
+	void __iomem *base = i2c_dev->base;
+	struct device *dev = i2c_dev->dev;
+	u32 oar1, oar2, mask;
+	int id, ret;
+
+	if (slave->flags & I2C_CLIENT_PEC) {
+		dev_err(dev, "SMBus PEC not supported in slave mode\n");
+		return -EINVAL;
+	}
+
+	if (stm32f7_i2c_is_slave_busy(i2c_dev)) {
+		dev_err(dev, "Too much slave registered\n");
+		return -EBUSY;
+	}
+
+	ret = stm32f7_i2c_get_free_slave_id(i2c_dev, slave, &id);
+	if (ret)
+		return ret;
+
+	if (!(stm32f7_i2c_is_slave_registered(i2c_dev))) {
+		ret = clk_enable(i2c_dev->clk);
+		if (ret) {
+			dev_err(dev, "Failed to enable clock\n");
+			return ret;
+		}
+	}
+
+	if (id == 0) {
+		/* Configure Own Address 1 */
+		oar1 = readl_relaxed(i2c_dev->base + STM32F7_I2C_OAR1);
+		oar1 &= ~STM32F7_I2C_OAR1_MASK;
+		if (slave->flags & I2C_CLIENT_TEN) {
+			oar1 |= STM32F7_I2C_OAR1_OA1_10(slave->addr);
+			oar1 |= STM32F7_I2C_OAR1_OA1MODE;
+		} else {
+			oar1 |= STM32F7_I2C_OAR1_OA1_7(slave->addr);
+		}
+		oar1 |= STM32F7_I2C_OAR1_OA1EN;
+		i2c_dev->slave[id] = slave;
+		writel_relaxed(oar1, i2c_dev->base + STM32F7_I2C_OAR1);
+	} else if (id == 1) {
+		/* Configure Own Address 2 */
+		oar2 = readl_relaxed(i2c_dev->base + STM32F7_I2C_OAR2);
+		oar2 &= ~STM32F7_I2C_OAR2_MASK;
+		if (slave->flags & I2C_CLIENT_TEN) {
+			ret = -EOPNOTSUPP;
+			goto exit;
+		}
+
+		oar2 |= STM32F7_I2C_OAR2_OA2_7(slave->addr);
+		oar2 |= STM32F7_I2C_OAR2_OA2EN;
+		i2c_dev->slave[id] = slave;
+		writel_relaxed(oar2, i2c_dev->base + STM32F7_I2C_OAR2);
+	} else {
+		ret = -ENODEV;
+		goto exit;
+	}
+
+	/* Enable ACK */
+	stm32f7_i2c_clr_bits(base + STM32F7_I2C_CR2, STM32F7_I2C_CR2_NACK);
+
+	/* Enable Address match interrupt, error interrupt and enable I2C  */
+	mask = STM32F7_I2C_CR1_ADDRIE | STM32F7_I2C_CR1_ERRIE |
+		STM32F7_I2C_CR1_PE;
+	stm32f7_i2c_set_bits(base + STM32F7_I2C_CR1, mask);
+
+	return 0;
+
+exit:
+	if (!(stm32f7_i2c_is_slave_registered(i2c_dev)))
+		clk_disable(i2c_dev->clk);
+
+	return ret;
+}
+
+static int stm32f7_i2c_unreg_slave(struct i2c_client *slave)
+{
+	struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(slave->adapter);
+	void __iomem *base = i2c_dev->base;
+	u32 mask;
+	int id, ret;
+
+	ret = stm32f7_i2c_get_slave_id(i2c_dev, slave, &id);
+	if (ret)
+		return ret;
+
+	WARN_ON(!i2c_dev->slave[id]);
+
+	if (id == 0) {
+		mask = STM32F7_I2C_OAR1_OA1EN;
+		stm32f7_i2c_clr_bits(base + STM32F7_I2C_OAR1, mask);
+	} else {
+		mask = STM32F7_I2C_OAR2_OA2EN;
+		stm32f7_i2c_clr_bits(base + STM32F7_I2C_OAR2, mask);
+	}
+
+	i2c_dev->slave[id] = NULL;
+
+	if (!(stm32f7_i2c_is_slave_registered(i2c_dev))) {
+		stm32f7_i2c_disable_irq(i2c_dev, STM32F7_I2C_ALL_IRQ_MASK);
+		clk_disable(i2c_dev->clk);
+	}
+
+	return 0;
+}
+
 static u32 stm32f7_i2c_func(struct i2c_adapter *adap)
 {
-	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR;
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR |
+		I2C_FUNC_SLAVE;
 }
 
 static struct i2c_algorithm stm32f7_i2c_algo = {
 	.master_xfer = stm32f7_i2c_xfer,
 	.functionality = stm32f7_i2c_func,
+	.reg_slave = stm32f7_i2c_reg_slave,
+	.unreg_slave = stm32f7_i2c_unreg_slave,
 };
 
 static int stm32f7_i2c_probe(struct platform_device *pdev)
-- 
2.7.4

[RESEND PATCH v1 3/6] i2c: i2c-stm32f7: Add initial SMBus protocols support

[Pierre-Yves MORDRET]

This patch adds SMBus support for I2C controller embedded in STM32F7 Soc.
All SMBus protocols are implemented except SMBus-specific protocols.

Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
---
  Version history:
    v1:
       * Initial
---
---
 drivers/i2c/busses/i2c-stm32f7.c | 377 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 368 insertions(+), 9 deletions(-)

diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index aff1750..f228196 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -37,6 +37,7 @@
 #define STM32F7_I2C_CR2				0x04
 #define STM32F7_I2C_OAR1			0x08
 #define STM32F7_I2C_OAR2			0x0C
+#define STM32F7_I2C_PECR			0x20
 #define STM32F7_I2C_TIMINGR			0x10
 #define STM32F7_I2C_ISR				0x18
 #define STM32F7_I2C_ICR				0x1C
@@ -44,6 +45,7 @@
 #define STM32F7_I2C_TXDR			0x28
 
 /* STM32F7 I2C control 1 */
+#define STM32F7_I2C_CR1_PECEN			BIT(23)
 #define STM32F7_I2C_CR1_SBC			BIT(16)
 #define STM32F7_I2C_CR1_ANFOFF			BIT(12)
 #define STM32F7_I2C_CR1_ERRIE			BIT(7)
@@ -67,6 +69,7 @@
 						| STM32F7_I2C_CR1_TXIE)
 
 /* STM32F7 I2C control 2 */
+#define STM32F7_I2C_CR2_PECBYTE			BIT(26)
 #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)
@@ -111,6 +114,7 @@
 				(((n) & STM32F7_I2C_ISR_ADDCODE_MASK) >> 17)
 #define STM32F7_I2C_ISR_DIR			BIT(16)
 #define STM32F7_I2C_ISR_BUSY			BIT(15)
+#define STM32F7_I2C_ISR_PECERR			BIT(11)
 #define STM32F7_I2C_ISR_ARLO			BIT(9)
 #define STM32F7_I2C_ISR_BERR			BIT(8)
 #define STM32F7_I2C_ISR_TCR			BIT(7)
@@ -123,6 +127,7 @@
 #define STM32F7_I2C_ISR_TXE			BIT(0)
 
 /* STM32F7 I2C Interrupt Clear */
+#define STM32F7_I2C_ICR_PECCF			BIT(11)
 #define STM32F7_I2C_ICR_ARLOCF			BIT(9)
 #define STM32F7_I2C_ICR_BERRCF			BIT(8)
 #define STM32F7_I2C_ICR_STOPCF			BIT(5)
@@ -225,6 +230,14 @@ struct stm32f7_i2c_timings {
  * @buf: data buffer
  * @result: result of the transfer
  * @stop: last I2C msg to be sent, i.e. STOP to be generated
+ * @smbus: boolean to know if the I2C IP is used in SMBus mode
+ * @size: type of SMBus protocol
+ * @read_write: direction of SMBus protocol
+ * SMBus block read and SMBus block write - block read process call protocols
+ * @smbus_buff: buffer to be used for SMBus protocol transfer. It will
+ * contain a maximum of 32 bytes of data + byte command + byte count + PEC
+ * This buffer has to be 32-bit aligned to be compliant with memory address
+ * register in DMA mode.
  */
 struct stm32f7_i2c_msg {
 	u16 addr;
@@ -232,6 +245,10 @@ struct stm32f7_i2c_msg {
 	u8 *buf;
 	int result;
 	bool stop;
+	bool smbus;
+	int size;
+	char read_write;
+	u8 smbus_buf[I2C_SMBUS_BLOCK_MAX + 3] __aligned(4);
 };
 
 /**
@@ -649,6 +666,29 @@ static void stm32f7_i2c_reload(struct stm32f7_i2c_dev *i2c_dev)
 	writel_relaxed(cr2, i2c_dev->base + STM32F7_I2C_CR2);
 }
 
+static void stm32f7_i2c_smbus_reload(struct stm32f7_i2c_dev *i2c_dev)
+{
+	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+	u32 cr2;
+	u8 *val;
+
+	/*
+	 * For I2C_SMBUS_BLOCK_DATA && I2C_SMBUS_BLOCK_PROC_CALL, the first
+	 * data received inform us how many data will follow.
+	 */
+	stm32f7_i2c_read_rx_data(i2c_dev);
+
+	/*
+	 * Update NBYTES with the value read to continue the transfer
+	 */
+	val = f7_msg->buf - sizeof(u8);
+	f7_msg->count = *val;
+	cr2 = readl_relaxed(i2c_dev->base + STM32F7_I2C_CR2);
+	cr2 &= ~(STM32F7_I2C_CR2_NBYTES_MASK | 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;
@@ -732,6 +772,237 @@ static void stm32f7_i2c_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
 	writel_relaxed(cr2, base + STM32F7_I2C_CR2);
 }
 
+static int stm32f7_i2c_smbus_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
+				      unsigned short flags, u8 command,
+				      union i2c_smbus_data *data)
+{
+	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+	struct device *dev = i2c_dev->dev;
+	void __iomem *base = i2c_dev->base;
+	u32 cr1, cr2;
+	int i;
+
+	f7_msg->result = 0;
+	reinit_completion(&i2c_dev->complete);
+
+	cr2 = readl_relaxed(base + STM32F7_I2C_CR2);
+	cr1 = readl_relaxed(base + STM32F7_I2C_CR1);
+
+	/* Set transfer direction */
+	cr2 &= ~STM32F7_I2C_CR2_RD_WRN;
+	if (f7_msg->read_write)
+		cr2 |= STM32F7_I2C_CR2_RD_WRN;
+
+	/* Set slave address */
+	cr2 &= ~(STM32F7_I2C_CR2_ADD10 | STM32F7_I2C_CR2_SADD7_MASK);
+	cr2 |= STM32F7_I2C_CR2_SADD7(f7_msg->addr);
+
+	f7_msg->smbus_buf[0] = command;
+	switch (f7_msg->size) {
+	case I2C_SMBUS_QUICK:
+		f7_msg->stop = true;
+		f7_msg->count = 0;
+		break;
+	case I2C_SMBUS_BYTE:
+		f7_msg->stop = true;
+		f7_msg->count = 1;
+		break;
+	case I2C_SMBUS_BYTE_DATA:
+		if (f7_msg->read_write) {
+			f7_msg->stop = false;
+			f7_msg->count = 1;
+			cr2 &= ~STM32F7_I2C_CR2_RD_WRN;
+		} else {
+			f7_msg->stop = true;
+			f7_msg->count = 2;
+			f7_msg->smbus_buf[1] = data->byte;
+		}
+		break;
+	case I2C_SMBUS_WORD_DATA:
+		if (f7_msg->read_write) {
+			f7_msg->stop = false;
+			f7_msg->count = 1;
+			cr2 &= ~STM32F7_I2C_CR2_RD_WRN;
+		} else {
+			f7_msg->stop = true;
+			f7_msg->count = 3;
+			f7_msg->smbus_buf[1] = data->word & 0xff;
+			f7_msg->smbus_buf[2] = data->word >> 8;
+		}
+		break;
+	case I2C_SMBUS_BLOCK_DATA:
+		if (f7_msg->read_write) {
+			f7_msg->stop = false;
+			f7_msg->count = 1;
+			cr2 &= ~STM32F7_I2C_CR2_RD_WRN;
+		} else {
+			f7_msg->stop = true;
+			if (data->block[0] > I2C_SMBUS_BLOCK_MAX ||
+			    !data->block[0]) {
+				dev_err(dev, "Invalid block write size %d\n",
+					data->block[0]);
+				return -EINVAL;
+			}
+			f7_msg->count = data->block[0] + 2;
+			for (i = 1; i < f7_msg->count; i++)
+				f7_msg->smbus_buf[i] = data->block[i - 1];
+		}
+		break;
+	case I2C_SMBUS_PROC_CALL:
+		f7_msg->stop = false;
+		f7_msg->count = 3;
+		f7_msg->smbus_buf[1] = data->word & 0xff;
+		f7_msg->smbus_buf[2] = data->word >> 8;
+		cr2 &= ~STM32F7_I2C_CR2_RD_WRN;
+		f7_msg->read_write = I2C_SMBUS_READ;
+		break;
+	case I2C_SMBUS_BLOCK_PROC_CALL:
+		f7_msg->stop = false;
+		if (data->block[0] > I2C_SMBUS_BLOCK_MAX - 1) {
+			dev_err(dev, "Invalid block write size %d\n",
+				data->block[0]);
+			return -EINVAL;
+		}
+		f7_msg->count = data->block[0] + 2;
+		for (i = 1; i < f7_msg->count; i++)
+			f7_msg->smbus_buf[i] = data->block[i - 1];
+		cr2 &= ~STM32F7_I2C_CR2_RD_WRN;
+		f7_msg->read_write = I2C_SMBUS_READ;
+		break;
+	default:
+		dev_err(dev, "Unsupported smbus protocol %d\n", f7_msg->size);
+		return -EOPNOTSUPP;
+	};
+
+	f7_msg->buf = f7_msg->smbus_buf;
+
+	/* Configure PEC */
+	if ((flags & I2C_CLIENT_PEC) && f7_msg->size != I2C_SMBUS_QUICK) {
+		cr1 |= STM32F7_I2C_CR1_PECEN;
+		cr2 |= STM32F7_I2C_CR2_PECBYTE;
+		if (!f7_msg->read_write)
+			f7_msg->count++;
+	} else {
+		cr1 &= ~STM32F7_I2C_CR1_PECEN;
+		cr2 &= ~STM32F7_I2C_CR2_PECBYTE;
+	}
+
+	/* Set number of bytes to be transferred */
+	cr2 &= ~(STM32F7_I2C_CR2_NBYTES_MASK | STM32F7_I2C_CR2_RELOAD);
+	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 (cr2 & STM32F7_I2C_CR2_RD_WRN)
+		cr1 |= STM32F7_I2C_CR1_RXIE;
+	else
+		cr1 |= STM32F7_I2C_CR1_TXIE;
+
+	/* Set Start bit */
+	cr2 |= STM32F7_I2C_CR2_START;
+
+	i2c_dev->master_mode = true;
+
+	/* Write configurations registers */
+	writel_relaxed(cr1, base + STM32F7_I2C_CR1);
+	writel_relaxed(cr2, base + STM32F7_I2C_CR2);
+
+	return 0;
+}
+
+static void stm32f7_i2c_smbus_rep_start(struct stm32f7_i2c_dev *i2c_dev)
+{
+	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+	void __iomem *base = i2c_dev->base;
+	u32 cr1, cr2;
+
+	cr2 = readl_relaxed(base + STM32F7_I2C_CR2);
+	cr1 = readl_relaxed(base + STM32F7_I2C_CR1);
+
+	/* Set transfer direction */
+	cr2 |= STM32F7_I2C_CR2_RD_WRN;
+
+	switch (f7_msg->size) {
+	case I2C_SMBUS_BYTE_DATA:
+		f7_msg->count = 1;
+		break;
+	case I2C_SMBUS_WORD_DATA:
+	case I2C_SMBUS_PROC_CALL:
+		f7_msg->count = 2;
+		break;
+	case I2C_SMBUS_BLOCK_DATA:
+	case I2C_SMBUS_BLOCK_PROC_CALL:
+		f7_msg->count = 1;
+		cr2 |= STM32F7_I2C_CR2_RELOAD;
+		break;
+	};
+
+	f7_msg->buf = f7_msg->smbus_buf;
+	f7_msg->stop = true;
+
+	/* Add one byte for PEC if needed */
+	if (cr1 & STM32F7_I2C_CR1_PECEN)
+		f7_msg->count++;
+
+	/* Set number of bytes to be transferred */
+	cr2 &= ~(STM32F7_I2C_CR2_NBYTES_MASK);
+	cr2 |= STM32F7_I2C_CR2_NBYTES(f7_msg->count);
+
+	/*
+	 * Configure RX/TX interrupt:
+	 */
+	cr1 &= ~(STM32F7_I2C_CR1_RXIE | STM32F7_I2C_CR1_TXIE);
+	cr1 |= STM32F7_I2C_CR1_RXIE;
+
+	/* Configure 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 int stm32f7_i2c_smbus_check_pec(struct stm32f7_i2c_dev *i2c_dev)
+{
+	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+	u8 count, internal_pec, received_pec;
+
+	internal_pec = readl_relaxed(i2c_dev->base + STM32F7_I2C_PECR);
+
+	switch (f7_msg->size) {
+	case I2C_SMBUS_BYTE:
+	case I2C_SMBUS_BYTE_DATA:
+		received_pec = f7_msg->smbus_buf[1];
+		break;
+	case I2C_SMBUS_WORD_DATA:
+	case I2C_SMBUS_PROC_CALL:
+		received_pec = f7_msg->smbus_buf[2];
+		break;
+	case I2C_SMBUS_BLOCK_DATA:
+	case I2C_SMBUS_BLOCK_PROC_CALL:
+		count = f7_msg->smbus_buf[0];
+		received_pec = f7_msg->smbus_buf[count];
+		break;
+	default:
+		dev_err(i2c_dev->dev, "Unsupported smbus protocol for PEC\n");
+		return -EINVAL;
+	};
+
+	if (internal_pec != received_pec) {
+		dev_err(i2c_dev->dev, "Bad PEC 0x%02x vs. 0x%02x\n",
+			internal_pec, received_pec);
+		return -EBADMSG;
+	}
+
+	return 0;
+}
+
 static bool stm32f7_i2c_is_addr_match(struct i2c_client *slave, u32 addcode)
 {
 	u32 addr;
@@ -1023,6 +1294,8 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
 		if (f7_msg->stop) {
 			mask = STM32F7_I2C_CR2_STOP;
 			stm32f7_i2c_set_bits(base + STM32F7_I2C_CR2, mask);
+		} else if (f7_msg->smbus) {
+			stm32f7_i2c_smbus_rep_start(i2c_dev);
 		} else {
 			i2c_dev->msg_id++;
 			i2c_dev->msg++;
@@ -1030,13 +1303,12 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
 		}
 	}
 
-	/*
-	 * 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);
+	if (status & STM32F7_I2C_ISR_TCR) {
+		if (f7_msg->smbus)
+			stm32f7_i2c_smbus_reload(i2c_dev);
+		else
+			stm32f7_i2c_reload(i2c_dev);
+	}
 
 	return IRQ_HANDLED;
 }
@@ -1065,6 +1337,12 @@ static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
 		f7_msg->result = -EAGAIN;
 	}
 
+	if (status & STM32F7_I2C_ISR_PECERR) {
+		dev_err(dev, "<%s>: PEC error in reception\n", __func__);
+		writel_relaxed(STM32F7_I2C_ICR_PECCF, base + STM32F7_I2C_ICR);
+		f7_msg->result = -EINVAL;
+	}
+
 	/* Disable interrupts */
 	if (stm32f7_i2c_is_slave_registered(i2c_dev))
 		mask = STM32F7_I2C_XFER_IRQ_MASK;
@@ -1089,6 +1367,7 @@ static int stm32f7_i2c_xfer(struct i2c_adapter *i2c_adap,
 	i2c_dev->msg = msgs;
 	i2c_dev->msg_num = num;
 	i2c_dev->msg_id = 0;
+	f7_msg->smbus = false;
 
 	ret = clk_enable(i2c_dev->clk);
 	if (ret) {
@@ -1118,6 +1397,82 @@ static int stm32f7_i2c_xfer(struct i2c_adapter *i2c_adap,
 	return (ret < 0) ? ret : num;
 }
 
+static int stm32f7_i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
+				  unsigned short flags, char read_write,
+				  u8 command, int size,
+				  union i2c_smbus_data *data)
+{
+	struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(adapter);
+	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+	struct device *dev = i2c_dev->dev;
+	unsigned long timeout;
+	int i, ret;
+
+	f7_msg->addr = addr;
+	f7_msg->size = size;
+	f7_msg->read_write = read_write;
+	f7_msg->smbus = true;
+
+	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;
+
+	ret = stm32f7_i2c_smbus_xfer_msg(i2c_dev, flags, command, data);
+	if (ret)
+		goto clk_free;
+
+	timeout = wait_for_completion_timeout(&i2c_dev->complete,
+					      i2c_dev->adap.timeout);
+	ret = f7_msg->result;
+	if (ret)
+		goto clk_free;
+
+	if (!timeout) {
+		dev_dbg(dev, "Access to slave 0x%x timed out\n", f7_msg->addr);
+		ret = -ETIMEDOUT;
+		goto clk_free;
+	}
+
+	/* Check PEC */
+	if ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK && read_write) {
+		ret = stm32f7_i2c_smbus_check_pec(i2c_dev);
+		if (ret)
+			goto clk_free;
+	}
+
+	if (read_write && size != I2C_SMBUS_QUICK) {
+		switch (size) {
+		case I2C_SMBUS_BYTE:
+		case I2C_SMBUS_BYTE_DATA:
+			data->byte = f7_msg->smbus_buf[0];
+		break;
+		case I2C_SMBUS_WORD_DATA:
+		case I2C_SMBUS_PROC_CALL:
+			data->word = f7_msg->smbus_buf[0] |
+				(f7_msg->smbus_buf[1] << 8);
+		break;
+		case I2C_SMBUS_BLOCK_DATA:
+		case I2C_SMBUS_BLOCK_PROC_CALL:
+		for (i = 0; i <= f7_msg->smbus_buf[0]; i++)
+			data->block[i] = f7_msg->smbus_buf[i];
+		break;
+		default:
+			dev_err(dev, "Unsupported smbus transaction\n");
+			ret = -EINVAL;
+		}
+	}
+
+clk_free:
+	clk_disable(i2c_dev->clk);
+	return ret;
+}
+
 static int stm32f7_i2c_reg_slave(struct i2c_client *slave)
 {
 	struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(slave->adapter);
@@ -1229,12 +1584,16 @@ static int stm32f7_i2c_unreg_slave(struct i2c_client *slave)
 
 static u32 stm32f7_i2c_func(struct i2c_adapter *adap)
 {
-	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR |
-		I2C_FUNC_SLAVE;
+	return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SLAVE |
+		I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
+		I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
+		I2C_FUNC_SMBUS_BLOCK_DATA | I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
+		I2C_FUNC_SMBUS_PROC_CALL | I2C_FUNC_SMBUS_PEC;
 }
 
 static struct i2c_algorithm stm32f7_i2c_algo = {
 	.master_xfer = stm32f7_i2c_xfer,
+	.smbus_xfer = stm32f7_i2c_smbus_xfer,
 	.functionality = stm32f7_i2c_func,
 	.reg_slave = stm32f7_i2c_reg_slave,
 	.unreg_slave = stm32f7_i2c_unreg_slave,
-- 
2.7.4

[RESEND PATCH v1 4/6] i2c: i2c-stm32: Add generic DMA API

[Pierre-Yves MORDRET]

This patch adds a generic DMA API to implement DMA support for i2c-stm32fx
drivers

Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
---
  Version history:
    v1:
       * Initial
---
---
 drivers/i2c/busses/i2c-stm32.c | 153 +++++++++++++++++++++++++++++++++++++++++
 drivers/i2c/busses/i2c-stm32.h |  37 ++++++++++
 2 files changed, 190 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-stm32.c

diff --git a/drivers/i2c/busses/i2c-stm32.c b/drivers/i2c/busses/i2c-stm32.c
new file mode 100644
index 0000000..d75fbcb
--- /dev/null
+++ b/drivers/i2c/busses/i2c-stm32.c
@@ -0,0 +1,153 @@
+/*
+ * i2c-stm32.c
+ *
+ * Copyright (C) M'boumba Cedric Madianga 2017
+ * Author: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
+ *
+ * License terms:  GNU General Public License (GPL), version 2
+ */
+
+#include "i2c-stm32.h"
+
+/* Functions for DMA support */
+struct stm32_i2c_dma *stm32_i2c_dma_request(struct device *dev,
+					    dma_addr_t phy_addr,
+					    u32 txdr_offset,
+					    u32 rxdr_offset)
+{
+	struct stm32_i2c_dma *dma;
+	struct dma_slave_config dma_sconfig;
+	int ret;
+
+	dma = devm_kzalloc(dev, sizeof(*dma), GFP_KERNEL);
+	if (!dma)
+		return NULL;
+
+	/* Request and configure I2C TX dma channel */
+	dma->chan_tx = dma_request_slave_channel(dev, "tx");
+	if (!dma->chan_tx) {
+		dev_dbg(dev, "can't request DMA tx channel\n");
+		ret = -EINVAL;
+		goto fail_al;
+	}
+
+	memset(&dma_sconfig, 0, sizeof(dma_sconfig));
+	dma_sconfig.dst_addr = phy_addr + txdr_offset;
+	dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+	dma_sconfig.dst_maxburst = 1;
+	dma_sconfig.direction = DMA_MEM_TO_DEV;
+	ret = dmaengine_slave_config(dma->chan_tx, &dma_sconfig);
+	if (ret < 0) {
+		dev_err(dev, "can't configure tx channel\n");
+		goto fail_tx;
+	}
+
+	/* Request and configure I2C RX dma channel */
+	dma->chan_rx = dma_request_slave_channel(dev, "rx");
+	if (!dma->chan_rx) {
+		dev_err(dev, "can't request DMA rx channel\n");
+		ret = -EINVAL;
+		goto fail_tx;
+	}
+
+	memset(&dma_sconfig, 0, sizeof(dma_sconfig));
+	dma_sconfig.src_addr = phy_addr + rxdr_offset;
+	dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+	dma_sconfig.src_maxburst = 1;
+	dma_sconfig.direction = DMA_DEV_TO_MEM;
+	ret = dmaengine_slave_config(dma->chan_rx, &dma_sconfig);
+	if (ret < 0) {
+		dev_err(dev, "can't configure rx channel\n");
+		goto fail_rx;
+	}
+
+	init_completion(&dma->dma_complete);
+
+	dev_info(dev, "using %s (tx) and %s (rx) for DMA transfers\n",
+		 dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx));
+
+	return dma;
+
+fail_rx:
+	dma_release_channel(dma->chan_rx);
+fail_tx:
+	dma_release_channel(dma->chan_tx);
+fail_al:
+	devm_kfree(dev, dma);
+	dev_info(dev, "can't use DMA\n");
+
+	return NULL;
+}
+
+void stm32_i2c_dma_free(struct stm32_i2c_dma *dma)
+{
+	dma->dma_buf = 0;
+	dma->dma_len = 0;
+
+	dma_release_channel(dma->chan_tx);
+	dma->chan_tx = NULL;
+
+	dma_release_channel(dma->chan_rx);
+	dma->chan_rx = NULL;
+
+	dma->chan_using = NULL;
+}
+
+int stm32_i2c_prep_dma_xfer(struct device *dev, struct stm32_i2c_dma *dma,
+			    bool rd_wr, u32 len, u8 *buf,
+			    dma_async_tx_callback callback,
+			    void *dma_async_param)
+{
+	struct dma_async_tx_descriptor *txdesc;
+	struct device *chan_dev;
+	int ret;
+
+	if (rd_wr) {
+		dma->chan_using = dma->chan_rx;
+		dma->dma_transfer_dir = DMA_DEV_TO_MEM;
+		dma->dma_data_dir = DMA_FROM_DEVICE;
+	} else {
+		dma->chan_using = dma->chan_tx;
+		dma->dma_transfer_dir = DMA_MEM_TO_DEV;
+		dma->dma_data_dir = DMA_TO_DEVICE;
+	}
+
+	dma->dma_len = len;
+	chan_dev = dma->chan_using->device->dev;
+
+	dma->dma_buf = dma_map_single(chan_dev, buf, dma->dma_len,
+				      dma->dma_data_dir);
+	if (dma_mapping_error(chan_dev, dma->dma_buf)) {
+		dev_err(dev, "DMA mapping failed\n");
+		return -EINVAL;
+	}
+
+	txdesc = dmaengine_prep_slave_single(dma->chan_using, dma->dma_buf,
+					     dma->dma_len,
+					     dma->dma_transfer_dir,
+					     DMA_PREP_INTERRUPT);
+	if (!txdesc) {
+		dev_err(dev, "Not able to get desc for DMA xfer\n");
+		ret = -EINVAL;
+		goto err;
+	}
+
+	reinit_completion(&dma->dma_complete);
+
+	txdesc->callback = callback;
+	txdesc->callback_param = dma_async_param;
+	ret = dma_submit_error(dmaengine_submit(txdesc));
+	if (ret < 0) {
+		dev_err(dev, "DMA submit failed\n");
+		goto err;
+	}
+
+	dma_async_issue_pending(dma->chan_using);
+
+	return 0;
+
+err:
+	dma_unmap_single(chan_dev, dma->dma_buf, dma->dma_len,
+			 dma->dma_data_dir);
+	return ret;
+}
diff --git a/drivers/i2c/busses/i2c-stm32.h b/drivers/i2c/busses/i2c-stm32.h
index d4f9cef..868755f 100644
--- a/drivers/i2c/busses/i2c-stm32.h
+++ b/drivers/i2c/busses/i2c-stm32.h
@@ -11,6 +11,10 @@
 #ifndef _I2C_STM32_H
 #define _I2C_STM32_H
 
+#include <linux/dma-direction.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+
 enum stm32_i2c_speed {
 	STM32_I2C_SPEED_STANDARD, /* 100 kHz */
 	STM32_I2C_SPEED_FAST, /* 400 kHz */
@@ -18,4 +22,37 @@ enum stm32_i2c_speed {
 	STM32_I2C_SPEED_END,
 };
 
+/**
+ * struct stm32_i2c_dma - DMA specific data
+ * @chan_tx: dma channel for TX transfer
+ * @chan_rx: dma channel for RX transfer
+ * @chan_using: dma channel used for the current transfer (TX or RX)
+ * @dma_buf: dma buffer
+ * @dma_len: dma buffer len
+ * @dma_transfer_dir: dma transfer direction indicator
+ * @dma_data_dir: dma transfer mode indicator
+ * @dma_complete: dma transfer completion
+ */
+struct stm32_i2c_dma {
+	struct dma_chan *chan_tx;
+	struct dma_chan *chan_rx;
+	struct dma_chan *chan_using;
+	dma_addr_t dma_buf;
+	unsigned int dma_len;
+	enum dma_transfer_direction dma_transfer_dir;
+	enum dma_data_direction dma_data_dir;
+	struct completion dma_complete;
+};
+
+struct stm32_i2c_dma *stm32_i2c_dma_request(struct device *dev,
+					    dma_addr_t phy_addr,
+					    u32 txdr_offset, u32 rxdr_offset);
+
+void stm32_i2c_dma_free(struct stm32_i2c_dma *dma);
+
+int stm32_i2c_prep_dma_xfer(struct device *dev, struct stm32_i2c_dma *dma,
+			    bool rd_wr, u32 len, u8 *buf,
+			    dma_async_tx_callback callback,
+			    void *dma_async_param);
+
 #endif /* _I2C_STM32_H */
-- 
2.7.4

[RESEND PATCH v1 5/6] i2c: i2c-stm32f7: Add DMA support

[Pierre-Yves MORDRET]

This patch adds DMA support for i2c-stm32f7 driver

Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
---
  Version history:
    v1:
       * Initial
---
---
 drivers/i2c/busses/Makefile      |   3 +-
 drivers/i2c/busses/i2c-stm32f7.c | 216 +++++++++++++++++++++++++++++++++++----
 2 files changed, 198 insertions(+), 21 deletions(-)

diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 2ce8576..8dbfaf0 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -95,7 +95,8 @@ 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-$(CONFIG_I2C_STM32F7)	+= i2c-stm32f7.o
+i2c-stm32f7-drv-objs := i2c-stm32f7.o i2c-stm32.o
+obj-$(CONFIG_I2C_STM32F7)	+= i2c-stm32f7-drv.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
index f228196..593efa5 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -47,6 +47,8 @@
 /* STM32F7 I2C control 1 */
 #define STM32F7_I2C_CR1_PECEN			BIT(23)
 #define STM32F7_I2C_CR1_SBC			BIT(16)
+#define STM32F7_I2C_CR1_RXDMAEN			BIT(15)
+#define STM32F7_I2C_CR1_TXDMAEN			BIT(14)
 #define STM32F7_I2C_CR1_ANFOFF			BIT(12)
 #define STM32F7_I2C_CR1_ERRIE			BIT(7)
 #define STM32F7_I2C_CR1_TCIE			BIT(6)
@@ -142,6 +144,7 @@
 #define STM32F7_I2C_TIMINGR_SCLL(n)		((n) & 0xff)
 
 #define STM32F7_I2C_MAX_LEN			0xff
+#define STM32F7_I2C_DMA_LEN_MIN			0x1
 #define STM32F7_I2C_MAX_SLAVE			0x2
 
 #define STM32F7_I2C_DNF_DEFAULT			0
@@ -270,6 +273,8 @@ struct stm32f7_i2c_msg {
  * @slave_dir: transfer direction for the current slave device
  * @master_mode: boolean to know in which mode the I2C is running (master or
  * slave)
+ * @dma: dma data
+ * @use_dma: boolean to know if dma is used in the current transfer
  */
 struct stm32f7_i2c_dev {
 	struct i2c_adapter adap;
@@ -288,6 +293,8 @@ struct stm32f7_i2c_dev {
 	struct i2c_client *slave_running;
 	u32 slave_dir;
 	bool master_mode;
+	struct stm32_i2c_dma *dma;
+	bool use_dma;
 };
 
 /**
@@ -599,6 +606,25 @@ static int stm32f7_i2c_setup_timing(struct stm32f7_i2c_dev *i2c_dev,
 	return 0;
 }
 
+static void stm32f7_i2c_disable_dma_req(struct stm32f7_i2c_dev *i2c_dev)
+{
+	void __iomem *base = i2c_dev->base;
+	u32 mask = STM32F7_I2C_CR1_RXDMAEN | STM32F7_I2C_CR1_TXDMAEN;
+
+	stm32f7_i2c_clr_bits(base + STM32F7_I2C_CR1, mask);
+}
+
+static void stm32f7_i2c_dma_callback(void *arg)
+{
+	struct stm32f7_i2c_dev *i2c_dev = (struct stm32f7_i2c_dev *)arg;
+	struct stm32_i2c_dma *dma = i2c_dev->dma;
+	struct device *dev = dma->chan_using->device->dev;
+
+	stm32f7_i2c_disable_dma_req(i2c_dev);
+	dma_unmap_single(dev, dma->dma_buf, dma->dma_len, dma->dma_data_dir);
+	complete(&dma->dma_complete);
+}
+
 static void stm32f7_i2c_hw_config(struct stm32f7_i2c_dev *i2c_dev)
 {
 	struct stm32f7_i2c_timings *t = &i2c_dev->timing;
@@ -653,6 +679,9 @@ static void stm32f7_i2c_reload(struct stm32f7_i2c_dev *i2c_dev)
 	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
 	u32 cr2;
 
+	if (i2c_dev->use_dma)
+		f7_msg->count -= STM32F7_I2C_MAX_LEN;
+
 	cr2 = readl_relaxed(i2c_dev->base + STM32F7_I2C_CR2);
 
 	cr2 &= ~STM32F7_I2C_CR2_NBYTES_MASK;
@@ -712,6 +741,7 @@ static void stm32f7_i2c_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
 	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
 	void __iomem *base = i2c_dev->base;
 	u32 cr1, cr2;
+	int ret;
 
 	f7_msg->addr = msg->addr;
 	f7_msg->buf = msg->buf;
@@ -753,14 +783,35 @@ static void stm32f7_i2c_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
 	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);
+	/* Clear DMA req and TX/RX interrupt */
+	cr1 &= ~(STM32F7_I2C_CR1_RXIE | STM32F7_I2C_CR1_TXIE |
+			STM32F7_I2C_CR1_RXDMAEN | STM32F7_I2C_CR1_TXDMAEN);
+
+	/* Configure DMA or enable RX/TX interrupt */
+	i2c_dev->use_dma = false;
+	if (i2c_dev->dma && f7_msg->count >= STM32F7_I2C_DMA_LEN_MIN) {
+		ret = stm32_i2c_prep_dma_xfer(i2c_dev->dev, i2c_dev->dma,
+					      msg->flags & I2C_M_RD,
+					      f7_msg->count, f7_msg->buf,
+					      stm32f7_i2c_dma_callback,
+					      i2c_dev);
+		if (!ret)
+			i2c_dev->use_dma = true;
+		else
+			dev_warn(i2c_dev->dev, "can't use DMA\n");
+	}
 
-	/* 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;
+	if (!i2c_dev->use_dma) {
+		if (msg->flags & I2C_M_RD)
+			cr1 |= STM32F7_I2C_CR1_RXIE;
+		else
+			cr1 |= STM32F7_I2C_CR1_TXIE;
+	} else {
+		if (msg->flags & I2C_M_RD)
+			cr1 |= STM32F7_I2C_CR1_RXDMAEN;
+		else
+			cr1 |= STM32F7_I2C_CR1_TXDMAEN;
+	}
 
 	/* Configure Start/Repeated Start */
 	cr2 |= STM32F7_I2C_CR2_START;
@@ -780,7 +831,7 @@ static int stm32f7_i2c_smbus_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
 	struct device *dev = i2c_dev->dev;
 	void __iomem *base = i2c_dev->base;
 	u32 cr1, cr2;
-	int i;
+	int i, ret;
 
 	f7_msg->result = 0;
 	reinit_completion(&i2c_dev->complete);
@@ -895,14 +946,35 @@ static int stm32f7_i2c_smbus_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
 	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);
+	/* Clear DMA req and TX/RX interrupt */
+	cr1 &= ~(STM32F7_I2C_CR1_RXIE | STM32F7_I2C_CR1_TXIE |
+			STM32F7_I2C_CR1_RXDMAEN | STM32F7_I2C_CR1_TXDMAEN);
+
+	/* Configure DMA or enable RX/TX interrupt */
+	i2c_dev->use_dma = false;
+	if (i2c_dev->dma && f7_msg->count >= STM32F7_I2C_DMA_LEN_MIN) {
+		ret = stm32_i2c_prep_dma_xfer(i2c_dev->dev, i2c_dev->dma,
+					      cr2 & STM32F7_I2C_CR2_RD_WRN,
+					      f7_msg->count, f7_msg->buf,
+					      stm32f7_i2c_dma_callback,
+					      i2c_dev);
+		if (!ret)
+			i2c_dev->use_dma = true;
+		else
+			dev_warn(i2c_dev->dev, "can't use DMA\n");
+	}
 
-	/* Enable RX/TX interrupt according to msg direction */
-	if (cr2 & STM32F7_I2C_CR2_RD_WRN)
-		cr1 |= STM32F7_I2C_CR1_RXIE;
-	else
-		cr1 |= STM32F7_I2C_CR1_TXIE;
+	if (!i2c_dev->use_dma) {
+		if (cr2 & STM32F7_I2C_CR2_RD_WRN)
+			cr1 |= STM32F7_I2C_CR1_RXIE;
+		else
+			cr1 |= STM32F7_I2C_CR1_TXIE;
+	} else {
+		if (cr2 & STM32F7_I2C_CR2_RD_WRN)
+			cr1 |= STM32F7_I2C_CR1_RXDMAEN;
+		else
+			cr1 |= STM32F7_I2C_CR1_TXDMAEN;
+	}
 
 	/* Set Start bit */
 	cr2 |= STM32F7_I2C_CR2_START;
@@ -921,6 +993,7 @@ static void stm32f7_i2c_smbus_rep_start(struct stm32f7_i2c_dev *i2c_dev)
 	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
 	void __iomem *base = i2c_dev->base;
 	u32 cr1, cr2;
+	int ret;
 
 	cr2 = readl_relaxed(base + STM32F7_I2C_CR2);
 	cr1 = readl_relaxed(base + STM32F7_I2C_CR1);
@@ -960,6 +1033,35 @@ static void stm32f7_i2c_smbus_rep_start(struct stm32f7_i2c_dev *i2c_dev)
 	cr1 &= ~(STM32F7_I2C_CR1_RXIE | STM32F7_I2C_CR1_TXIE);
 	cr1 |= STM32F7_I2C_CR1_RXIE;
 
+	/*
+	 * Configure DMA or enable RX/TX interrupt:
+	 * For I2C_SMBUS_BLOCK_DATA and I2C_SMBUS_BLOCK_PROC_CALL we don't use
+	 * dma as we don't know in advance how many data will be received
+	 */
+	cr1 &= ~(STM32F7_I2C_CR1_RXIE | STM32F7_I2C_CR1_TXIE |
+		 STM32F7_I2C_CR1_RXDMAEN | STM32F7_I2C_CR1_TXDMAEN);
+
+	i2c_dev->use_dma = false;
+	if (i2c_dev->dma && f7_msg->count >= STM32F7_I2C_DMA_LEN_MIN &&
+	    f7_msg->size != I2C_SMBUS_BLOCK_DATA &&
+	    f7_msg->size != I2C_SMBUS_BLOCK_PROC_CALL) {
+		ret = stm32_i2c_prep_dma_xfer(i2c_dev->dev, i2c_dev->dma,
+					      cr2 & STM32F7_I2C_CR2_RD_WRN,
+					      f7_msg->count, f7_msg->buf,
+					      stm32f7_i2c_dma_callback,
+					      i2c_dev);
+
+		if (!ret)
+			i2c_dev->use_dma = true;
+		else
+			dev_warn(i2c_dev->dev, "can't use DMA\n");
+	}
+
+	if (!i2c_dev->use_dma)
+		cr1 |= STM32F7_I2C_CR1_RXIE;
+	else
+		cr1 |= STM32F7_I2C_CR1_RXDMAEN;
+
 	/* Configure Repeated Start */
 	cr2 |= STM32F7_I2C_CR2_START;
 
@@ -1248,7 +1350,7 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
 	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
 	void __iomem *base = i2c_dev->base;
 	u32 status, mask;
-	int ret;
+	int ret = IRQ_HANDLED;
 
 	/* Check if the interrupt if for a slave device */
 	if (!i2c_dev->master_mode) {
@@ -1285,8 +1387,12 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
 		/* Clear STOP flag */
 		writel_relaxed(STM32F7_I2C_ICR_STOPCF, base + STM32F7_I2C_ICR);
 
-		i2c_dev->master_mode = false;
-		complete(&i2c_dev->complete);
+		if (i2c_dev->use_dma) {
+			ret = IRQ_WAKE_THREAD;
+		} else {
+			i2c_dev->master_mode = false;
+			complete(&i2c_dev->complete);
+		}
 	}
 
 	/* Transfer complete */
@@ -1294,6 +1400,8 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
 		if (f7_msg->stop) {
 			mask = STM32F7_I2C_CR2_STOP;
 			stm32f7_i2c_set_bits(base + STM32F7_I2C_CR2, mask);
+		} else if (i2c_dev->use_dma) {
+			ret = IRQ_WAKE_THREAD;
 		} else if (f7_msg->smbus) {
 			stm32f7_i2c_smbus_rep_start(i2c_dev);
 		} else {
@@ -1310,6 +1418,46 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
 			stm32f7_i2c_reload(i2c_dev);
 	}
 
+	return ret;
+}
+
+static irqreturn_t stm32f7_i2c_isr_event_thread(int irq, void *data)
+{
+	struct stm32f7_i2c_dev *i2c_dev = data;
+	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+	struct stm32_i2c_dma *dma = i2c_dev->dma;
+	u32 status;
+	int ret;
+
+	/*
+	 * Wait for dma transfer completion before sending next message or
+	 * notity the end of xfer to the client
+	 */
+	ret = wait_for_completion_timeout(&i2c_dev->dma->dma_complete, HZ);
+	if (!ret) {
+		dev_dbg(i2c_dev->dev, "<%s>: Timed out\n", __func__);
+		stm32f7_i2c_disable_dma_req(i2c_dev);
+		dmaengine_terminate_all(dma->chan_using);
+		f7_msg->result = -ETIMEDOUT;
+	}
+
+	status = readl_relaxed(i2c_dev->base + STM32F7_I2C_ISR);
+
+	dev_dbg(i2c_dev->dev, "master evt irq (status=0x%08x, cr1=0x%08x)\n",
+		status, readl_relaxed(i2c_dev->base + STM32F7_I2C_CR1));
+	if (status & STM32F7_I2C_ISR_TC) {
+		if (f7_msg->smbus) {
+			stm32f7_i2c_smbus_rep_start(i2c_dev);
+		} else {
+			i2c_dev->msg_id++;
+			i2c_dev->msg++;
+			stm32f7_i2c_xfer_msg(i2c_dev, i2c_dev->msg);
+		}
+	} else {
+		i2c_dev->master_mode = false;
+		complete(&i2c_dev->complete);
+	}
+
 	return IRQ_HANDLED;
 }
 
@@ -1319,6 +1467,7 @@ static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
 	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
 	void __iomem *base = i2c_dev->base;
 	struct device *dev = i2c_dev->dev;
+	struct stm32_i2c_dma *dma = i2c_dev->dma;
 	u32 mask, status;
 
 	status = readl_relaxed(i2c_dev->base + STM32F7_I2C_ISR);
@@ -1350,6 +1499,12 @@ static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
 		mask = STM32F7_I2C_ALL_IRQ_MASK;
 	stm32f7_i2c_disable_irq(i2c_dev, mask);
 
+	/* Disable dma */
+	if (i2c_dev->use_dma) {
+		stm32f7_i2c_disable_dma_req(i2c_dev);
+		dmaengine_terminate_all(dma->chan_using);
+	}
+
 	i2c_dev->master_mode = false;
 	complete(&i2c_dev->complete);
 
@@ -1361,6 +1516,7 @@ static int stm32f7_i2c_xfer(struct i2c_adapter *i2c_adap,
 {
 	struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap);
 	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+	struct stm32_i2c_dma *dma = i2c_dev->dma;
 	unsigned long time_left;
 	int ret;
 
@@ -1388,6 +1544,8 @@ static int stm32f7_i2c_xfer(struct i2c_adapter *i2c_adap,
 	if (!time_left) {
 		dev_dbg(i2c_dev->dev, "Access to slave 0x%x timed out\n",
 			i2c_dev->msg->addr);
+		if (i2c_dev->use_dma)
+			dmaengine_terminate_all(dma->chan_using);
 		ret = -ETIMEDOUT;
 	}
 
@@ -1404,6 +1562,7 @@ static int stm32f7_i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
 {
 	struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(adapter);
 	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+	struct stm32_i2c_dma *dma = i2c_dev->dma;
 	struct device *dev = i2c_dev->dev;
 	unsigned long timeout;
 	int i, ret;
@@ -1435,6 +1594,8 @@ static int stm32f7_i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
 
 	if (!timeout) {
 		dev_dbg(dev, "Access to slave 0x%x timed out\n", f7_msg->addr);
+		if (i2c_dev->use_dma)
+			dmaengine_terminate_all(dma->chan_using);
 		ret = -ETIMEDOUT;
 		goto clk_free;
 	}
@@ -1608,6 +1769,7 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
 	u32 irq_error, irq_event, clk_rate, rise_time, fall_time;
 	struct i2c_adapter *adap;
 	struct reset_control *rst;
+	dma_addr_t phy_addr;
 	int ret;
 
 	i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
@@ -1618,6 +1780,7 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
 	i2c_dev->base = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(i2c_dev->base))
 		return PTR_ERR(i2c_dev->base);
+	phy_addr = (dma_addr_t)res->start;
 
 	irq_event = irq_of_parse_and_map(np, 0);
 	if (!irq_event) {
@@ -1664,8 +1827,11 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
 
 	i2c_dev->dev = &pdev->dev;
 
-	ret = devm_request_irq(&pdev->dev, irq_event, stm32f7_i2c_isr_event, 0,
-			       pdev->name, i2c_dev);
+	ret = devm_request_threaded_irq(&pdev->dev, irq_event,
+					stm32f7_i2c_isr_event,
+					stm32f7_i2c_isr_event_thread,
+					IRQF_ONESHOT,
+					pdev->name, i2c_dev);
 	if (ret) {
 		dev_err(&pdev->dev, "Failed to request irq event %i\n",
 			irq_event);
@@ -1716,6 +1882,11 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
 
 	init_completion(&i2c_dev->complete);
 
+	/* Init DMA config if supported */
+	i2c_dev->dma = stm32_i2c_dma_request(i2c_dev->dev, phy_addr,
+					     STM32F7_I2C_TXDR,
+					     STM32F7_I2C_RXDR);
+
 	ret = i2c_add_adapter(adap);
 	if (ret)
 		goto clk_free;
@@ -1738,6 +1909,11 @@ static int stm32f7_i2c_remove(struct platform_device *pdev)
 {
 	struct stm32f7_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
 
+	if (i2c_dev->dma) {
+		stm32_i2c_dma_free(i2c_dev->dma);
+		i2c_dev->dma = NULL;
+	}
+
 	i2c_del_adapter(&i2c_dev->adap);
 
 	clk_unprepare(i2c_dev->clk);
-- 
2.7.4

[RESEND PATCH v1 6/6] i2c: i2c-stm32f7: Implement I2C recovery mechanism

[Pierre-Yves MORDRET]

Feature prevents I2C lock-ups. Mechanism resets I2C state machine
and releases SCL/SDA signals but preserves I2C registers.

Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
---
  Version history:
    v1:
       * Initial
---
---
 drivers/i2c/busses/i2c-stm32f7.c | 32 +++++++++++++++++++++++++++++---
 1 file changed, 29 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index 593efa5..428bf96 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -718,6 +718,20 @@ static void stm32f7_i2c_smbus_reload(struct stm32f7_i2c_dev *i2c_dev)
 	writel_relaxed(cr2, i2c_dev->base + STM32F7_I2C_CR2);
 }
 
+static int stm32f7_i2c_recover_bus(struct i2c_adapter *i2c_adap)
+{
+	struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap);
+
+	dev_info(i2c_dev->dev, "Trying to recover bus\n");
+
+	stm32f7_i2c_clr_bits(i2c_dev->base + STM32F7_I2C_CR1,
+			     STM32F7_I2C_CR1_PE);
+
+	stm32f7_i2c_hw_config(i2c_dev);
+
+	return 0;
+}
+
 static int stm32f7_i2c_wait_free_bus(struct stm32f7_i2c_dev *i2c_dev)
 {
 	u32 status;
@@ -727,12 +741,18 @@ static int stm32f7_i2c_wait_free_bus(struct stm32f7_i2c_dev *i2c_dev)
 					 status,
 					 !(status & STM32F7_I2C_ISR_BUSY),
 					 10, 1000);
+	if (!ret)
+		return 0;
+
+	dev_info(i2c_dev->dev, "bus busy\n");
+
+	ret = i2c_recover_bus(&i2c_dev->adap);
 	if (ret) {
-		dev_dbg(i2c_dev->dev, "bus busy\n");
-		ret = -EBUSY;
+		dev_err(i2c_dev->dev, "Failed to recover the bus (%d)\n", ret);
+		return ret;
 	}
 
-	return ret;
+	return -EBUSY;
 }
 
 static void stm32f7_i2c_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
@@ -1476,6 +1496,7 @@ static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
 	if (status & STM32F7_I2C_ISR_BERR) {
 		dev_err(dev, "<%s>: Bus error\n", __func__);
 		writel_relaxed(STM32F7_I2C_ICR_BERRCF, base + STM32F7_I2C_ICR);
+		i2c_recover_bus(&i2c_dev->adap);
 		f7_msg->result = -EIO;
 	}
 
@@ -1760,6 +1781,10 @@ static struct i2c_algorithm stm32f7_i2c_algo = {
 	.unreg_slave = stm32f7_i2c_unreg_slave,
 };
 
+static struct i2c_bus_recovery_info stm32f7_i2c_recovery_info = {
+	.recover_bus = stm32f7_i2c_recover_bus,
+};
+
 static int stm32f7_i2c_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
@@ -1879,6 +1904,7 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
 	adap->algo = &stm32f7_i2c_algo;
 	adap->dev.parent = &pdev->dev;
 	adap->dev.of_node = pdev->dev.of_node;
+	adap->bus_recovery_info = &stm32f7_i2c_recovery_info;
 
 	init_completion(&i2c_dev->complete);
 
-- 
2.7.4

[RESEND PATCH v1 0/6] Add different features for I2C

[Pierre-Yves MORDRET]

Append new I2C STM32F7 feature set. This includes 10 bit support, slave
support, SMBBus protocols support, DMA Support and eventually an I2C recovery
mechanism.
resend after rebasing on last kernel.

---
  Version history:
    v1:
        * Initial
---
Pierre-Yves MORDRET (6):
  i2c: i2c-stm32f7: Add 10-bit address support
  i2c: i2c-stm32f7: Add slave support
  i2c: i2c-stm32f7: Add initial SMBus protocols support
  i2c: i2c-stm32: Add generic DMA API
  i2c: i2c-stm32f7: Add DMA support
  i2c: i2c-stm32f7: Implement I2C recovery mechanism

 drivers/i2c/busses/Kconfig       |    1 +
 drivers/i2c/busses/Makefile      |    3 +-
 drivers/i2c/busses/i2c-stm32.c   |  153 ++++++
 drivers/i2c/busses/i2c-stm32.h   |   37 ++
 drivers/i2c/busses/i2c-stm32f7.c | 1047 +++++++++++++++++++++++++++++++++++++-
 5 files changed, 1214 insertions(+), 27 deletions(-)
 create mode 100644 drivers/i2c/busses/i2c-stm32.c

-- 
2.7.4