[Patch V4 1/2] i2c: imx: add low power i2c bus driver

[Patch V4 1/2] i2c: imx: add low power i2c bus driver

[Gao Pan]

This patch adds lpi2c bus driver to support new i.MX products
which use lpi2c instead of the old imx i2c.

The lpi2c can continue operating in stop mode when an appropriate
clock is available. It is also designed for low CPU overhead with
DMA offloading of FIFO register accesses.

Signed-off-by: Gao Pan <pandy.gao@nxp.com>
Reviewed-by: Fugang Duan <B38611@freescale.com>
---
V2:
 -stop i2c transfer under the wrong condition
 -add timeout check in while() domain

V3:
 -fix typo inside commit message and the driver.

V4:
As Vladimir Zapolskiy's review, the version do below changes:
 -split devicetree binding with driver
 -prepare clk in probe()
 -replace "1<<n" BIT(n)
 -remove unnecessary variables
 -fix typo
 -use module_platform_driver()
 -use i2c_add_adapter()

 drivers/i2c/busses/Kconfig         |  10 +
 drivers/i2c/busses/Makefile        |   1 +
 drivers/i2c/busses/i2c-imx-lpi2c.c | 640 +++++++++++++++++++++++++++++++++++++
 3 files changed, 651 insertions(+)

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index d252276..7cff9ec 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -597,6 +597,16 @@ config I2C_IMX
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-imx.
 
+config I2C_IMX_LPI2C
+	tristate "IMX Low Power I2C interface"
+	depends on ARCH_MXC || COMPILE_TEST
+	help
+          Say Y here if you want to use the Low Power IIC bus controller
+          on the Freescale i.MX processors.
+
+          This driver can also be built as a module. If so, the module
+          will be called i2c-imx-lpi2c.
+
 config I2C_IOP3XX
 	tristate "Intel IOPx3xx and IXP4xx on-chip I2C interface"
 	depends on ARCH_IOP32X || ARCH_IOP33X || ARCH_IXP4XX || ARCH_IOP13XX
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 29764cc..05195cd 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -56,6 +56,7 @@ obj-$(CONFIG_I2C_HIX5HD2)	+= i2c-hix5hd2.o
 obj-$(CONFIG_I2C_IBM_IIC)	+= i2c-ibm_iic.o
 obj-$(CONFIG_I2C_IMG)		+= i2c-img-scb.o
 obj-$(CONFIG_I2C_IMX)		+= i2c-imx.o
+obj-$(CONFIG_I2C_IMX_LPI2C)	+= i2c-imx-lpi2c.o
 obj-$(CONFIG_I2C_IOP3XX)	+= i2c-iop3xx.o
 obj-$(CONFIG_I2C_JZ4780)	+= i2c-jz4780.o
 obj-$(CONFIG_I2C_KEMPLD)	+= i2c-kempld.o
diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c b/drivers/i2c/busses/i2c-imx-lpi2c.c
new file mode 100644
index 0000000..c434fd0
--- /dev/null
+++ b/drivers/i2c/busses/i2c-imx-lpi2c.c
@@ -0,0 +1,640 @@
+/*
+ * This is i.MX low power i2c controller driver.
+ *
+ * Copyright 2016 Freescale Semiconductor, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+#define DRIVER_NAME "imx-lpi2c"
+
+#define LPI2C_PARAM	0x04	/* i2c RX/TX FIFO size */
+#define LPI2C_MCR	0x10	/* i2c contrl register */
+#define LPI2C_MSR	0x14	/* i2c status register */
+#define LPI2C_MIER	0x18	/* i2c interrupt enable */
+#define LPI2C_MCFGR0	0x20	/* i2c master configuration */
+#define LPI2C_MCFGR1	0x24	/* i2c master configuration */
+#define LPI2C_MCFGR2	0x28	/* i2c master configuration */
+#define LPI2C_MCFGR3	0x2C	/* i2c master configuration */
+#define LPI2C_MCCR0	0x48	/* i2c master clk configuration */
+#define LPI2C_MCCR1	0x50	/* i2c master clk configuration */
+#define LPI2C_MFCR	0x58	/* i2c master FIFO control */
+#define LPI2C_MFSR	0x5C	/* i2c master FIFO status */
+#define LPI2C_MTDR	0x60	/* i2c master TX data register */
+#define LPI2C_MRDR	0x70	/* i2c master RX data register */
+
+/* i2c command */
+#define TRAN_DATA	0X00
+#define RECV_DATA	0X01
+#define GEN_STOP	0X02
+#define RECV_DISCARD	0X03
+#define GEN_START	0X04
+#define START_NACK	0X05
+#define START_HIGH	0X06
+#define START_HIGH_NACK	0X07
+
+#define MCR_MEN		BIT(0)
+#define MCR_RST		BIT(1)
+#define MCR_DOZEN	BIT(2)
+#define MCR_DBGEN	BIT(3)
+#define MCR_RTF		BIT(8)
+#define MCR_RRF		BIT(9)
+#define MSR_TDF		BIT(0)
+#define MSR_RDF		BIT(1)
+#define MSR_SDF		BIT(9)
+#define MSR_NDF		BIT(10)
+#define MSR_ALF		BIT(11)
+#define MSR_MBF		BIT(24)
+#define MSR_BBF		BIT(25)
+#define MIER_TDIE	BIT(0)
+#define MIER_RDIE	BIT(1)
+#define MIER_SDIE	BIT(9)
+#define MIER_NDIE	BIT(10)
+#define MCFGR1_AUTOSTOP	BIT(8)
+#define MCFGR1_IGNACK	BIT(9)
+#define MRDR_RXEMPTY	BIT(14)
+
+#define I2C_CLK_RATIO	2
+#define CHUNK_DATA	256
+
+#define LPI2C_RX_FIFOSIZE	4
+#define LPI2C_TX_FIFOSIZE	4
+
+#define LPI2C_DEFAULT_RATE	100000
+#define STARDARD_MAX_BITRATE	400000
+#define FAST_MAX_BITRATE	1000000
+#define FAST_PLUS_MAX_BITRATE	3400000
+#define HIGHSPEED_MAX_BITRATE	5000000
+
+enum lpi2c_imx_mode {
+	STANDARD,	/* 100+Kbps */
+	FAST,		/* 400+Kbps */
+	FAST_PLUS,	/* 1.0+Mbps */
+	HS,		/* 3.4+Mbps */
+	ULTRA_FAST,	/* 5.0+Mbps */
+};
+
+enum lpi2c_imx_pincfg {
+	TWO_PIN_OD,
+	TWO_PIN_OO,
+	TWO_PIN_PP,
+	FOUR_PIN_PP,
+};
+
+struct lpi2c_imx_struct {
+	struct i2c_adapter	adapter;
+	struct clk		*clk;
+	void __iomem		*base;
+	__u8			*rx_buf;
+	__u8			*tx_buf;
+	struct completion	complete;
+	unsigned int		msglen;
+	unsigned int		delivered;
+	unsigned int		block_data;
+	unsigned int		bitrate;
+	enum lpi2c_imx_mode	mode;
+};
+
+static void lpi2c_imx_intctrl(struct lpi2c_imx_struct *lpi2c_imx,
+				unsigned int enable)
+{
+	writel(enable, lpi2c_imx->base + LPI2C_MIER);
+}
+
+static int lpi2c_imx_bus_busy(struct lpi2c_imx_struct *lpi2c_imx)
+{
+	unsigned long orig_jiffies = jiffies;
+	unsigned int temp;
+
+	while (1) {
+		temp = readl(lpi2c_imx->base + LPI2C_MSR);
+
+		/* check for arbitration lost, clear if set */
+		if (temp & MSR_ALF) {
+			writel(temp, lpi2c_imx->base + LPI2C_MSR);
+			return -EAGAIN;
+		}
+
+		if (temp & (MSR_BBF | MSR_MBF))
+			break;
+
+		if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
+			dev_dbg(&lpi2c_imx->adapter.dev, "bus not work\n");
+			return -ETIMEDOUT;
+		}
+		schedule();
+	}
+
+	return 0;
+}
+
+static void lpi2c_imx_set_mode(struct lpi2c_imx_struct *lpi2c_imx)
+{
+	unsigned int bitrate = lpi2c_imx->bitrate;
+	enum lpi2c_imx_mode mode;
+
+	if (bitrate < STARDARD_MAX_BITRATE)
+		mode = STANDARD;
+	else if (bitrate < FAST_MAX_BITRATE)
+		mode = FAST;
+	else if (bitrate < FAST_PLUS_MAX_BITRATE)
+		mode = FAST_PLUS;
+	else if (bitrate < HIGHSPEED_MAX_BITRATE)
+		mode = HS;
+	else
+		mode = ULTRA_FAST;
+
+	lpi2c_imx->mode = mode;
+}
+
+static int lpi2c_imx_start(struct lpi2c_imx_struct *lpi2c_imx,
+						struct i2c_msg *msgs)
+{
+	unsigned int temp;
+	u8 read;
+
+	temp = readl(lpi2c_imx->base + LPI2C_MCR);
+	temp |= MCR_RRF | MCR_RTF;
+	writel(temp, lpi2c_imx->base + LPI2C_MCR);
+	writel(0x7f00, lpi2c_imx->base + LPI2C_MSR);
+
+	read = msgs->flags & I2C_M_RD;
+	temp = (msgs->addr << 1 | read) | (GEN_START << 8);
+	writel(temp, lpi2c_imx->base + LPI2C_MTDR);
+
+	return lpi2c_imx_bus_busy(lpi2c_imx);
+}
+
+static void lpi2c_imx_stop(struct lpi2c_imx_struct *lpi2c_imx)
+{
+	unsigned long orig_jiffies = jiffies;
+	unsigned int temp;
+
+	writel(GEN_STOP << 8, lpi2c_imx->base + LPI2C_MTDR);
+
+	do {
+		temp = readl(lpi2c_imx->base + LPI2C_MSR);
+		if (temp & MSR_SDF)
+			break;
+
+		if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
+			dev_dbg(&lpi2c_imx->adapter.dev, "stop timeout\n");
+			break;
+		}
+		schedule();
+
+	} while (1);
+}
+
+/* CLKLO = I2C_CLK_RATIO * CLKHI, SETHOLD = CLKHI, DATAVD = CLKHI/2 */
+static int lpi2c_imx_config(struct lpi2c_imx_struct *lpi2c_imx)
+{
+	u8 prescale, filt, sethold, clkhi, clklo, datavd;
+	unsigned int clk_rate, clk_cycle;
+	enum lpi2c_imx_pincfg pincfg;
+	unsigned int temp;
+
+	lpi2c_imx_set_mode(lpi2c_imx);
+
+	clk_rate = clk_get_rate(lpi2c_imx->clk);
+	if (lpi2c_imx->mode == HS || lpi2c_imx->mode == ULTRA_FAST)
+		filt = 0;
+	else
+		filt = 2;
+
+	for (prescale = 0; prescale <= 7; prescale++) {
+		clk_cycle = clk_rate / ((1 << prescale) * lpi2c_imx->bitrate)
+			    - 3 - (filt >> 1);
+		clkhi = (clk_cycle + I2C_CLK_RATIO) / (I2C_CLK_RATIO + 1);
+		clklo = clk_cycle - clkhi;
+		if (clklo < 64)
+			break;
+	}
+
+	if (prescale > 7)
+		return -EINVAL;
+
+	/* set MCFGR1: PINCFG, PRESCALE, IGNACK */
+	if (lpi2c_imx->mode == ULTRA_FAST)
+		pincfg = TWO_PIN_OO;
+	else
+		pincfg = TWO_PIN_OD;
+	temp = prescale | pincfg << 24;
+
+	if (lpi2c_imx->mode == ULTRA_FAST)
+		temp |= MCFGR1_IGNACK;
+
+	writel(temp, lpi2c_imx->base + LPI2C_MCFGR1);
+
+	/* set MCFGR2: FILTSDA, FILTSCL */
+	temp = (filt << 16) | (filt << 24);
+	writel(temp, lpi2c_imx->base + LPI2C_MCFGR2);
+
+	/* set MCCR: DATAVD, SETHOLD, CLKHI, CLKLO */
+	sethold = clkhi;
+	datavd = clkhi >> 1;
+	temp = datavd << 24 | sethold << 16 | clkhi << 8 | clklo;
+
+	if (lpi2c_imx->mode == HS)
+		writel(temp, lpi2c_imx->base + LPI2C_MCCR1);
+	else
+		writel(temp, lpi2c_imx->base + LPI2C_MCCR0);
+
+	return 0;
+}
+
+static int lpi2c_imx_master_enable(struct lpi2c_imx_struct *lpi2c_imx)
+{
+	unsigned int temp;
+	int ret;
+
+	ret = clk_enable(lpi2c_imx->clk);
+	if (ret)
+		return ret;
+
+	temp = MCR_RST;
+	writel(temp, lpi2c_imx->base + LPI2C_MCR);
+	writel(0, lpi2c_imx->base + LPI2C_MCR);
+
+	ret = lpi2c_imx_config(lpi2c_imx);
+	if (ret)
+		return ret;
+
+	temp = readl(lpi2c_imx->base + LPI2C_MCR);
+	temp |= MCR_MEN;
+	writel(temp, lpi2c_imx->base + LPI2C_MCR);
+
+	return 0;
+}
+
+static int lpi2c_imx_master_disable(struct lpi2c_imx_struct *lpi2c_imx)
+{
+	unsigned int temp = 0;
+
+	temp = readl(lpi2c_imx->base + LPI2C_MCR);
+	temp &= ~MCR_MEN;
+	writel(temp, lpi2c_imx->base + LPI2C_MCR);
+
+	clk_disable(lpi2c_imx->clk);
+
+	return 0;
+}
+
+static int lpi2c_imx_msg_complete(struct lpi2c_imx_struct *lpi2c_imx)
+{
+	unsigned int timeout;
+
+	timeout = wait_for_completion_timeout(&lpi2c_imx->complete, HZ);
+
+	return timeout ? 0 : -ETIMEDOUT;
+}
+
+static int lpi2c_imx_txfifo_empty(struct lpi2c_imx_struct *lpi2c_imx)
+{
+	unsigned long orig_jiffies = jiffies;
+	u32 txcnt;
+
+	do {
+		txcnt = readl(lpi2c_imx->base + LPI2C_MFSR) & 0xff;
+
+		if (readl(lpi2c_imx->base + LPI2C_MSR) & MSR_NDF) {
+			dev_dbg(&lpi2c_imx->adapter.dev, "NDF detected\n");
+			return -EIO;
+		}
+
+		if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
+			dev_dbg(&lpi2c_imx->adapter.dev, "txfifo empty timeout\n");
+			return -ETIMEDOUT;
+		}
+		schedule();
+
+	} while (txcnt);
+
+	return 0;
+}
+
+static void lpi2c_imx_set_tx_watermark(struct lpi2c_imx_struct *lpi2c_imx)
+{
+	writel(LPI2C_TX_FIFOSIZE >> 1, lpi2c_imx->base + LPI2C_MFCR);
+}
+
+static void lpi2c_imx_set_rx_watermark(struct lpi2c_imx_struct *lpi2c_imx)
+{
+	unsigned int temp, remaining;
+
+	remaining = lpi2c_imx->msglen - lpi2c_imx->delivered;
+
+	if (remaining > (LPI2C_RX_FIFOSIZE >> 1))
+		temp = LPI2C_RX_FIFOSIZE >> 1;
+	else
+		temp = 0;
+
+	writel(temp << 16, lpi2c_imx->base + LPI2C_MFCR);
+}
+
+static void lpi2c_imx_write_txfifo(struct lpi2c_imx_struct *lpi2c_imx)
+{
+	unsigned int data, txcnt;
+
+	txcnt = readl(lpi2c_imx->base + LPI2C_MFSR) & 0xff;
+
+	while (txcnt < LPI2C_TX_FIFOSIZE) {
+		if (lpi2c_imx->delivered == lpi2c_imx->msglen)
+			break;
+
+		data = lpi2c_imx->tx_buf[lpi2c_imx->delivered++];
+		writel(data, lpi2c_imx->base + LPI2C_MTDR);
+		txcnt++;
+	}
+
+	if (lpi2c_imx->delivered < lpi2c_imx->msglen)
+		lpi2c_imx_intctrl(lpi2c_imx, MIER_TDIE | MIER_NDIE);
+	else
+		complete(&lpi2c_imx->complete);
+}
+
+static void lpi2c_imx_read_rxfifo(struct lpi2c_imx_struct *lpi2c_imx)
+{
+	unsigned int blocklen, remaining;
+	unsigned int temp, data;
+
+	do {
+		data = readl(lpi2c_imx->base + LPI2C_MRDR);
+		if (data & MRDR_RXEMPTY)
+			break;
+
+		lpi2c_imx->rx_buf[lpi2c_imx->delivered++] = data & 0xff;
+	} while (1);
+
+	/*
+	 * First byte is the length of remaining packet in the SMBus block
+	 * data read. Add it to msgs->len.
+	 */
+	if (lpi2c_imx->block_data) {
+		blocklen = lpi2c_imx->rx_buf[0];
+		lpi2c_imx->msglen += blocklen;
+	}
+
+	remaining = lpi2c_imx->msglen - lpi2c_imx->delivered;
+
+	if (!remaining) {
+		complete(&lpi2c_imx->complete);
+		return;
+	}
+
+	/* not finished, still waiting for rx data */
+	lpi2c_imx_set_rx_watermark(lpi2c_imx);
+
+	/* multiple receive commands */
+	if (lpi2c_imx->block_data) {
+		lpi2c_imx->block_data = 0;
+		temp = remaining;
+		temp |= (RECV_DATA << 8);
+		writel(temp, lpi2c_imx->base + LPI2C_MTDR);
+	} else if (!(lpi2c_imx->delivered & 0xff)) {
+		temp = remaining > CHUNK_DATA ? CHUNK_DATA - 1 : (remaining - 1);
+		temp |= (RECV_DATA << 8);
+		writel(temp, lpi2c_imx->base + LPI2C_MTDR);
+	}
+
+	lpi2c_imx_intctrl(lpi2c_imx, MIER_RDIE);
+}
+
+static void lpi2c_imx_write(struct lpi2c_imx_struct *lpi2c_imx,
+							struct i2c_msg *msgs)
+{
+	lpi2c_imx->tx_buf = msgs->buf;
+	lpi2c_imx_set_tx_watermark(lpi2c_imx);
+	lpi2c_imx_write_txfifo(lpi2c_imx);
+}
+
+static void lpi2c_imx_read(struct lpi2c_imx_struct *lpi2c_imx,
+							struct i2c_msg *msgs)
+{
+	unsigned int temp;
+
+	lpi2c_imx->rx_buf = msgs->buf;
+	lpi2c_imx->block_data = msgs->flags & I2C_M_RECV_LEN;
+
+	lpi2c_imx_set_rx_watermark(lpi2c_imx);
+	temp = msgs->len > CHUNK_DATA ? CHUNK_DATA - 1 : msgs->len - 1;
+	temp |= (RECV_DATA << 8);
+	writel(temp, lpi2c_imx->base + LPI2C_MTDR);
+
+	lpi2c_imx_intctrl(lpi2c_imx, MIER_RDIE | MIER_NDIE);
+}
+
+static int lpi2c_imx_xfer(struct i2c_adapter *adapter,
+						struct i2c_msg *msgs, int num)
+{
+	struct lpi2c_imx_struct *lpi2c_imx = i2c_get_adapdata(adapter);
+	unsigned int temp;
+	int i, result;
+
+	result = lpi2c_imx_master_enable(lpi2c_imx);
+	if (result)
+		return result;
+
+	for (i = 0; i < num; i++) {
+		result = lpi2c_imx_start(lpi2c_imx, &msgs[i]);
+		if (result)
+			goto disable;
+
+		/* quick smbus */
+		if (num == 1 && msgs[0].len == 0)
+			goto stop;
+
+		lpi2c_imx->delivered = 0;
+		lpi2c_imx->msglen = msgs[i].len;
+		init_completion(&lpi2c_imx->complete);
+
+		if (msgs[i].flags & I2C_M_RD)
+			lpi2c_imx_read(lpi2c_imx, &msgs[i]);
+		else
+			lpi2c_imx_write(lpi2c_imx, &msgs[i]);
+
+		result = lpi2c_imx_msg_complete(lpi2c_imx);
+		if (result)
+			goto stop;
+
+		if (!(msgs[i].flags & I2C_M_RD)) {
+			result = lpi2c_imx_txfifo_empty(lpi2c_imx);
+			if (result)
+				goto stop;
+		}
+	}
+
+stop:
+	lpi2c_imx_stop(lpi2c_imx);
+
+	temp = readl(lpi2c_imx->base + LPI2C_MSR);
+	if ((temp & MSR_NDF) && !result)
+		result = -EIO;
+
+disable:
+	lpi2c_imx_master_disable(lpi2c_imx);
+
+	dev_dbg(&lpi2c_imx->adapter.dev, "<%s> exit with: %s: %d\n", __func__,
+		(result < 0) ? "error" : "success msg",
+		(result < 0) ? result : num);
+
+	return (result < 0) ? result : num;
+}
+
+static irqreturn_t lpi2c_imx_isr(int irq, void *dev_id)
+{
+	struct lpi2c_imx_struct *lpi2c_imx = dev_id;
+	unsigned int temp;
+
+	lpi2c_imx_intctrl(lpi2c_imx, 0);
+	temp = readl(lpi2c_imx->base + LPI2C_MSR);
+
+	if (temp & MSR_RDF) {
+		lpi2c_imx_read_rxfifo(lpi2c_imx);
+		return IRQ_HANDLED;
+	}
+
+	if (temp & MSR_TDF) {
+		lpi2c_imx_write_txfifo(lpi2c_imx);
+		return IRQ_HANDLED;
+	}
+
+	complete(&lpi2c_imx->complete);
+
+	return IRQ_HANDLED;
+}
+
+static u32 lpi2c_imx_func(struct i2c_adapter *adapter)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
+	I2C_FUNC_SMBUS_READ_BLOCK_DATA;
+}
+
+static struct i2c_algorithm lpi2c_imx_algo = {
+	.master_xfer	= lpi2c_imx_xfer,
+	.functionality	= lpi2c_imx_func,
+};
+
+static const struct of_device_id lpi2c_imx_of_match[] = {
+	{ .compatible = "fsl,imx8dv-lpi2c" },
+	{ .compatible = "fsl,imx7ulp-lpi2c" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, lpi2c_imx_of_match)
+
+static int lpi2c_imx_probe(struct platform_device *pdev)
+{
+	struct lpi2c_imx_struct *lpi2c_imx;
+	struct resource *res;
+	int irq, ret;
+
+	lpi2c_imx = devm_kzalloc(&pdev->dev,
+				sizeof(*lpi2c_imx), GFP_KERNEL);
+	if (!lpi2c_imx)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	lpi2c_imx->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(lpi2c_imx->base))
+		return PTR_ERR(lpi2c_imx->base);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "can't get irq number\n");
+		return irq;
+	}
+
+	lpi2c_imx->adapter.owner	= THIS_MODULE;
+	lpi2c_imx->adapter.algo		= &lpi2c_imx_algo;
+	lpi2c_imx->adapter.dev.parent	= &pdev->dev;
+	lpi2c_imx->adapter.dev.of_node	= pdev->dev.of_node;
+	strlcpy(lpi2c_imx->adapter.name, pdev->name,
+				sizeof(lpi2c_imx->adapter.name));
+
+	lpi2c_imx->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(lpi2c_imx->clk)) {
+		dev_err(&pdev->dev, "can't get I2C peripheral clock\n");
+		return PTR_ERR(lpi2c_imx->clk);
+	}
+
+	ret = clk_prepare(lpi2c_imx->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "clk prepare failed %d\n", ret);
+		return ret;
+	}
+
+	ret = of_property_read_u32(pdev->dev.of_node,
+				   "clock-frequency", &lpi2c_imx->bitrate);
+	if (ret)
+		lpi2c_imx->bitrate = LPI2C_DEFAULT_RATE;
+
+	ret = devm_request_irq(&pdev->dev, irq, lpi2c_imx_isr, 0,
+				pdev->name, lpi2c_imx);
+	if (ret) {
+		dev_err(&pdev->dev, "can't claim irq %d\n", irq);
+		return ret;
+	}
+
+	i2c_set_adapdata(&lpi2c_imx->adapter, lpi2c_imx);
+	platform_set_drvdata(pdev, lpi2c_imx);
+
+	ret = i2c_add_adapter(&lpi2c_imx->adapter);
+	if (ret) {
+		dev_err(&pdev->dev, "registration failed\n");
+		return ret;
+	}
+
+	dev_info(&lpi2c_imx->adapter.dev, "LPI2C adapter registered\n");
+
+	return 0;
+}
+
+static int lpi2c_imx_remove(struct platform_device *pdev)
+{
+	struct lpi2c_imx_struct *lpi2c_imx = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&lpi2c_imx->adapter);
+
+	return 0;
+}
+
+static struct platform_driver lpi2c_imx_driver = {
+	.probe = lpi2c_imx_probe,
+	.remove = lpi2c_imx_remove,
+	.driver = {
+		.name = DRIVER_NAME,
+		.of_match_table = lpi2c_imx_of_match,
+	},
+};
+
+module_platform_driver(lpi2c_imx_driver);
+
+MODULE_AUTHOR("Gao Pan <pandy.gao@nxp.com>");
+MODULE_DESCRIPTION("I2C adapter driver for LPI2C bus");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1

[Patch V4 2/2] i2c: imx: add devicetree binding for lpi2c

[Gao Pan]

Add a binding document for lpi2c driver

Signed-off-by: Gao Pan <pandy.gao@nxp.com>
---
 .../devicetree/bindings/i2c/i2c-imx-lpi2c.txt        | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-imx-lpi2c.txt b/Documentation/devicetree/bindings/i2c/i2c-imx-lpi2c.txt
new file mode 100644
index 0000000..edaf04f
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-imx-lpi2c.txt
@@ -0,0 +1,20 @@
+* Freescale Low Power Inter IC (LPI2C) for i.MX
+
+Required properties:
+- compatible :
+  - "fsl,imx8dv-lpi2c" for LPI2C compatible with the one integrated on i.MX8DV soc
+  - "fsl,imx7ulp-lpi2c" for LPI2C compatible with the one integrated on i.MX7ULP soc
+- reg : address and length of the lpi2c master registers
+- interrupt-parent : core interrupt controller
+- interrupts : lpi2c interrupt
+- clocks : lpi2c clock specifier
+
+Examples:
+
+lpi2c7: lpi2c7@40A50000 {
+	compatible = "fsl,imx8dv-lpi2c";
+	reg = <0x40A50000 0x10000>;
+	interrupt-parent = <&intc>;
+	interrupts = <GIC_SPI 37 IRQ_TYPE_LEVEL_HIGH>;
+	clocks = <&clks IMX7ULP_CLK_LPI2C7>;
+};
-- 
1.9.1

Re: [Patch V4 2/2] i2c: imx: add devicetree binding for lpi2c

[Vladimir Zapolskiy]

On 11/14/2016 11:23 AM, Gao Pan wrote:
> Add a binding document for lpi2c driver
>
> Signed-off-by: Gao Pan <pandy.gao@nxp.com>
> ---
>  .../devicetree/bindings/i2c/i2c-imx-lpi2c.txt        | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-imx-lpi2c.txt b/Documentation/devicetree/bindings/i2c/i2c-imx-lpi2c.txt
> new file mode 100644
> index 0000000..edaf04f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i2c/i2c-imx-lpi2c.txt
> @@ -0,0 +1,20 @@
> +* Freescale Low Power Inter IC (LPI2C) for i.MX
> +
> +Required properties:
> +- compatible :
> +  - "fsl,imx8dv-lpi2c" for LPI2C compatible with the one integrated on i.MX8DV soc
> +  - "fsl,imx7ulp-lpi2c" for LPI2C compatible with the one integrated on i.MX7ULP soc
> +- reg : address and length of the lpi2c master registers
> +- interrupt-parent : core interrupt controller
> +- interrupts : lpi2c interrupt
> +- clocks : lpi2c clock specifier

I don't know if description of standard properties is really needed,
probably Rob can advise.

My point is that pretty "interrupts-extended" is never mentioned, and
all three interrupt* properties are well described in interrupts.txt,
and in general there is no point to mention all those interrupts,
clocks, clock-names and friends properties again and again.

But here better to get a clarification from Rob.

> +
> +Examples:
> +
> +lpi2c7: lpi2c7@40A50000 {
> +	compatible = "fsl,imx8dv-lpi2c";
> +	reg = <0x40A50000 0x10000>;
> +	interrupt-parent = <&intc>;
> +	interrupts = <GIC_SPI 37 IRQ_TYPE_LEVEL_HIGH>;
> +	clocks = <&clks IMX7ULP_CLK_LPI2C7>;
> +};
>

Please rearrange the changes, devicetree binding change should be 1/2,
the driver change should be 2/2.

--
With best wishes,
Vladimir

Re: [Patch V4 1/2] i2c: imx: add low power i2c bus driver

[Vladimir Zapolskiy]

On 11/14/2016 11:23 AM, Gao Pan wrote:
> This patch adds lpi2c bus driver to support new i.MX products
> which use lpi2c instead of the old imx i2c.
>
> The lpi2c can continue operating in stop mode when an appropriate
> clock is available. It is also designed for low CPU overhead with
> DMA offloading of FIFO register accesses.
>
> Signed-off-by: Gao Pan <pandy.gao@nxp.com>
> Reviewed-by: Fugang Duan <B38611@freescale.com>
> ---

[snip]

> +
> +static int lpi2c_imx_master_enable(struct lpi2c_imx_struct *lpi2c_imx)
> +{
> +	unsigned int temp;
> +	int ret;
> +
> +	ret = clk_enable(lpi2c_imx->clk);
> +	if (ret)
> +		return ret;
> +
> +	temp = MCR_RST;
> +	writel(temp, lpi2c_imx->base + LPI2C_MCR);
> +	writel(0, lpi2c_imx->base + LPI2C_MCR);
> +
> +	ret = lpi2c_imx_config(lpi2c_imx);
> +	if (ret)
> +		return ret;

Missing clk_disable() on error path.

> +
> +	temp = readl(lpi2c_imx->base + LPI2C_MCR);
> +	temp |= MCR_MEN;
> +	writel(temp, lpi2c_imx->base + LPI2C_MCR);
> +
> +	return 0;
> +}
> +
> +static int lpi2c_imx_master_disable(struct lpi2c_imx_struct *lpi2c_imx)
> +{
> +	unsigned int temp = 0;

No need of assignment, just do a declaration "u32 temp;".

> +
> +	temp = readl(lpi2c_imx->base + LPI2C_MCR);
> +	temp &= ~MCR_MEN;
> +	writel(temp, lpi2c_imx->base + LPI2C_MCR);
> +
> +	clk_disable(lpi2c_imx->clk);
> +
> +	return 0;
> +}
> +
> +static int lpi2c_imx_msg_complete(struct lpi2c_imx_struct *lpi2c_imx)
> +{
> +	unsigned int timeout;

unsigned long timeout;

> +
> +	timeout = wait_for_completion_timeout(&lpi2c_imx->complete, HZ);
> +
> +	return timeout ? 0 : -ETIMEDOUT;
> +}
> +

[snip]

> +static void lpi2c_imx_read_rxfifo(struct lpi2c_imx_struct *lpi2c_imx)
> +{
> +	unsigned int blocklen, remaining;
> +	unsigned int temp, data;
> +
> +	do {
> +		data = readl(lpi2c_imx->base + LPI2C_MRDR);
> +		if (data & MRDR_RXEMPTY)
> +			break;
> +
> +		lpi2c_imx->rx_buf[lpi2c_imx->delivered++] = data & 0xff;
> +	} while (1);
> +
> +	/*
> +	 * First byte is the length of remaining packet in the SMBus block
> +	 * data read. Add it to msgs->len.
> +	 */
> +	if (lpi2c_imx->block_data) {
> +		blocklen = lpi2c_imx->rx_buf[0];
> +		lpi2c_imx->msglen += blocklen;
> +	}
> +
> +	remaining = lpi2c_imx->msglen - lpi2c_imx->delivered;
> +
> +	if (!remaining) {
> +		complete(&lpi2c_imx->complete);
> +		return;
> +	}
> +
> +	/* not finished, still waiting for rx data */
> +	lpi2c_imx_set_rx_watermark(lpi2c_imx);
> +
> +	/* multiple receive commands */
> +	if (lpi2c_imx->block_data) {
> +		lpi2c_imx->block_data = 0;
> +		temp = remaining;
> +		temp |= (RECV_DATA << 8);
> +		writel(temp, lpi2c_imx->base + LPI2C_MTDR);
> +	} else if (!(lpi2c_imx->delivered & 0xff)) {
> +		temp = remaining > CHUNK_DATA ? CHUNK_DATA - 1 : (remaining - 1);

checkpatch complains:

WARNING: line over 80 characters
#473: FILE: drivers/i2c/busses/i2c-imx-lpi2c.c:421:
+     temp = remaining > CHUNK_DATA ? CHUNK_DATA - 1 : (remaining - 1);

May be rewrite it as

	temp = (remaining > CHUNK_DATA ? CHUNK_DATA : remaining) - 1;

?

> +		temp |= (RECV_DATA << 8);
> +		writel(temp, lpi2c_imx->base + LPI2C_MTDR);
> +	}
> +
> +	lpi2c_imx_intctrl(lpi2c_imx, MIER_RDIE);
> +}
> +

[snip]

> +
> +static u32 lpi2c_imx_func(struct i2c_adapter *adapter)
> +{
> +	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
> +	I2C_FUNC_SMBUS_READ_BLOCK_DATA;

Please indent deeper the second line.

> +}
> +
> +static struct i2c_algorithm lpi2c_imx_algo = {
> +	.master_xfer	= lpi2c_imx_xfer,
> +	.functionality	= lpi2c_imx_func,
> +};
> +
> +static const struct of_device_id lpi2c_imx_of_match[] = {
> +	{ .compatible = "fsl,imx8dv-lpi2c" },
> +	{ .compatible = "fsl,imx7ulp-lpi2c" },

Please sort the compatibles alphanumerically.

> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, lpi2c_imx_of_match)

Missing closing ";"                        ^^^^^^

> +
> +static int lpi2c_imx_probe(struct platform_device *pdev)
> +{
> +	struct lpi2c_imx_struct *lpi2c_imx;
> +	struct resource *res;
> +	int irq, ret;
> +
> +	lpi2c_imx = devm_kzalloc(&pdev->dev,
> +				sizeof(*lpi2c_imx), GFP_KERNEL);

Please place it on a single line, it fits into 80 character limit.

> +	if (!lpi2c_imx)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	lpi2c_imx->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(lpi2c_imx->base))
> +		return PTR_ERR(lpi2c_imx->base);
> +
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0) {
> +		dev_err(&pdev->dev, "can't get irq number\n");
> +		return irq;
> +	}
> +
> +	lpi2c_imx->adapter.owner	= THIS_MODULE;
> +	lpi2c_imx->adapter.algo		= &lpi2c_imx_algo;
> +	lpi2c_imx->adapter.dev.parent	= &pdev->dev;
> +	lpi2c_imx->adapter.dev.of_node	= pdev->dev.of_node;
> +	strlcpy(lpi2c_imx->adapter.name, pdev->name,
> +				sizeof(lpi2c_imx->adapter.name));

checkpatch --strict complains:

CHECK: Alignment should match open parenthesis
#630: FILE: drivers/i2c/busses/i2c-imx-lpi2c.c:578:
+       strlcpy(lpi2c_imx->adapter.name, pdev->name,
+                               sizeof(lpi2c_imx->adapter.name));

> +
> +	lpi2c_imx->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(lpi2c_imx->clk)) {
> +		dev_err(&pdev->dev, "can't get I2C peripheral clock\n");
> +		return PTR_ERR(lpi2c_imx->clk);
> +	}
> +
> +	ret = clk_prepare(lpi2c_imx->clk);
> +	if (ret) {
> +		dev_err(&pdev->dev, "clk prepare failed %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = of_property_read_u32(pdev->dev.of_node,
> +				   "clock-frequency", &lpi2c_imx->bitrate);
> +	if (ret)
> +		lpi2c_imx->bitrate = LPI2C_DEFAULT_RATE;
> +
> +	ret = devm_request_irq(&pdev->dev, irq, lpi2c_imx_isr, 0,
> +				pdev->name, lpi2c_imx);
> +	if (ret) {
> +		dev_err(&pdev->dev, "can't claim irq %d\n", irq);
> +		return ret;

On error path you leak clk_prepare()'d lpi2c_imx->clk clock.

I would recommend to prepare the clock after successful
adapter registration.

> +	}
> +
> +	i2c_set_adapdata(&lpi2c_imx->adapter, lpi2c_imx);
> +	platform_set_drvdata(pdev, lpi2c_imx);
> +
> +	ret = i2c_add_adapter(&lpi2c_imx->adapter);
> +	if (ret) {
> +		dev_err(&pdev->dev, "registration failed\n");

Please remove this notification line, it is reported by I2C core.

> +		return ret;
> +	}
> +
> +	dev_info(&lpi2c_imx->adapter.dev, "LPI2C adapter registered\n");
> +
> +	return 0;
> +}
> +
> +static int lpi2c_imx_remove(struct platform_device *pdev)
> +{
> +	struct lpi2c_imx_struct *lpi2c_imx = platform_get_drvdata(pdev);
> +

Missing clk_unprepare(lpi2c_imx->clk clock);

> +	i2c_del_adapter(&lpi2c_imx->adapter);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver lpi2c_imx_driver = {
> +	.probe = lpi2c_imx_probe,
> +	.remove = lpi2c_imx_remove,
> +	.driver = {
> +		.name = DRIVER_NAME,
> +		.of_match_table = lpi2c_imx_of_match,
> +	},
> +};
> +
> +module_platform_driver(lpi2c_imx_driver);
> +
> +MODULE_AUTHOR("Gao Pan <pandy.gao@nxp.com>");
> +MODULE_DESCRIPTION("I2C adapter driver for LPI2C bus");
> +MODULE_LICENSE("GPL v2");
>

--
With best wishes,
Vladimir

RE: [Patch V4 1/2] i2c: imx: add low power i2c bus driver

[Pandy Gao]

 From: Vladimir Zapolskiy <mailto:vz@mleia.com> Sent: Thursday, November 17, 2016 8:59 AM
> To: Pandy Gao <pandy.gao@nxp.com>; wsa@the-dreams.de; u.kleine-
> koenig@pengutronix.de; cmo@melexis.com; robh@kernel.org
> Cc: linux-i2c@vger.kernel.org; Frank Li <frank.li@nxp.com>; Andy Duan
> <fugang.duan@nxp.com>
> Subject: Re: [Patch V4 1/2] i2c: imx: add low power i2c bus driver
> 
> On 11/14/2016 11:23 AM, Gao Pan wrote:
> > This patch adds lpi2c bus driver to support new i.MX products which
> > use lpi2c instead of the old imx i2c.
> >
> > The lpi2c can continue operating in stop mode when an appropriate
> > clock is available. It is also designed for low CPU overhead with DMA
> > offloading of FIFO register accesses.
> >
> > Signed-off-by: Gao Pan <pandy.gao@nxp.com>
> > Reviewed-by: Fugang Duan <B38611@freescale.com>
> > ---
> 
> [snip]
> 
> > +
> > +static int lpi2c_imx_master_enable(struct lpi2c_imx_struct
> > +*lpi2c_imx) {
> > +	unsigned int temp;
> > +	int ret;
> > +
> > +	ret = clk_enable(lpi2c_imx->clk);
> > +	if (ret)
> > +		return ret;
> > +
> > +	temp = MCR_RST;
> > +	writel(temp, lpi2c_imx->base + LPI2C_MCR);
> > +	writel(0, lpi2c_imx->base + LPI2C_MCR);
> > +
> > +	ret = lpi2c_imx_config(lpi2c_imx);
> > +	if (ret)
> > +		return ret;
> 
> Missing clk_disable() on error path.
 
Thanks, will change it in next  version. 

> > +
> > +	temp = readl(lpi2c_imx->base + LPI2C_MCR);
> > +	temp |= MCR_MEN;
> > +	writel(temp, lpi2c_imx->base + LPI2C_MCR);
> > +
> > +	return 0;
> > +}
> > +
> > +static int lpi2c_imx_master_disable(struct lpi2c_imx_struct
> > +*lpi2c_imx) {
> > +	unsigned int temp = 0;
> 
> No need of assignment, just do a declaration "u32 temp;".
 
Thanks.
 
> > +
> > +	temp = readl(lpi2c_imx->base + LPI2C_MCR);
> > +	temp &= ~MCR_MEN;
> > +	writel(temp, lpi2c_imx->base + LPI2C_MCR);
> > +
> > +	clk_disable(lpi2c_imx->clk);
> > +
> > +	return 0;
> > +}
> > +
> > +static int lpi2c_imx_msg_complete(struct lpi2c_imx_struct *lpi2c_imx)
> > +{
> > +	unsigned int timeout;
> 
> unsigned long timeout;

Thanks. 

> > +
> > +	timeout = wait_for_completion_timeout(&lpi2c_imx->complete, HZ);
> > +
> > +	return timeout ? 0 : -ETIMEDOUT;
> > +}
> > +
> 
> [snip]
> 
> > +static void lpi2c_imx_read_rxfifo(struct lpi2c_imx_struct *lpi2c_imx)
> > +{
> > +	unsigned int blocklen, remaining;
> > +	unsigned int temp, data;
> > +
> > +	do {
> > +		data = readl(lpi2c_imx->base + LPI2C_MRDR);
> > +		if (data & MRDR_RXEMPTY)
> > +			break;
> > +
> > +		lpi2c_imx->rx_buf[lpi2c_imx->delivered++] = data & 0xff;
> > +	} while (1);
> > +
> > +	/*
> > +	 * First byte is the length of remaining packet in the SMBus block
> > +	 * data read. Add it to msgs->len.
> > +	 */
> > +	if (lpi2c_imx->block_data) {
> > +		blocklen = lpi2c_imx->rx_buf[0];
> > +		lpi2c_imx->msglen += blocklen;
> > +	}
> > +
> > +	remaining = lpi2c_imx->msglen - lpi2c_imx->delivered;
> > +
> > +	if (!remaining) {
> > +		complete(&lpi2c_imx->complete);
> > +		return;
> > +	}
> > +
> > +	/* not finished, still waiting for rx data */
> > +	lpi2c_imx_set_rx_watermark(lpi2c_imx);
> > +
> > +	/* multiple receive commands */
> > +	if (lpi2c_imx->block_data) {
> > +		lpi2c_imx->block_data = 0;
> > +		temp = remaining;
> > +		temp |= (RECV_DATA << 8);
> > +		writel(temp, lpi2c_imx->base + LPI2C_MTDR);
> > +	} else if (!(lpi2c_imx->delivered & 0xff)) {
> > +		temp = remaining > CHUNK_DATA ? CHUNK_DATA - 1 :
> (remaining - 1);
> 
> checkpatch complains:
> 
> WARNING: line over 80 characters
> #473: FILE: drivers/i2c/busses/i2c-imx-lpi2c.c:421:
> +     temp = remaining > CHUNK_DATA ? CHUNK_DATA - 1 : (remaining - 1);
> 
> May be rewrite it as
> 
> 	temp = (remaining > CHUNK_DATA ? CHUNK_DATA : remaining) - 1;

Thanks, will change  it in next  version. 
 
> > +		temp |= (RECV_DATA << 8);
> > +		writel(temp, lpi2c_imx->base + LPI2C_MTDR);
> > +	}
> > +
> > +	lpi2c_imx_intctrl(lpi2c_imx, MIER_RDIE); }
> > +
> 
> [snip]
> 
> > +
> > +static u32 lpi2c_imx_func(struct i2c_adapter *adapter) {
> > +	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
> > +	I2C_FUNC_SMBUS_READ_BLOCK_DATA;
> 
> Please indent deeper the second line.

Thanks. 

> > +}
> > +
> > +static struct i2c_algorithm lpi2c_imx_algo = {
> > +	.master_xfer	= lpi2c_imx_xfer,
> > +	.functionality	= lpi2c_imx_func,
> > +};
> > +
> > +static const struct of_device_id lpi2c_imx_of_match[] = {
> > +	{ .compatible = "fsl,imx8dv-lpi2c" },
> > +	{ .compatible = "fsl,imx7ulp-lpi2c" },
> 
> Please sort the compatibles alphanumerically.

Thanks, will change it in next version. 

> > +	{ },
> > +};
> > +MODULE_DEVICE_TABLE(of, lpi2c_imx_of_match)
> 
> Missing closing ";"                        ^^^^^^

Thanks. 

> > +
> > +static int lpi2c_imx_probe(struct platform_device *pdev) {
> > +	struct lpi2c_imx_struct *lpi2c_imx;
> > +	struct resource *res;
> > +	int irq, ret;
> > +
> > +	lpi2c_imx = devm_kzalloc(&pdev->dev,
> > +				sizeof(*lpi2c_imx), GFP_KERNEL);
> 
> Please place it on a single line, it fits into 80 character limit.

Thanks, will change it in next version. 

> > +	if (!lpi2c_imx)
> > +		return -ENOMEM;
> > +
> > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	lpi2c_imx->base = devm_ioremap_resource(&pdev->dev, res);
> > +	if (IS_ERR(lpi2c_imx->base))
> > +		return PTR_ERR(lpi2c_imx->base);
> > +
> > +	irq = platform_get_irq(pdev, 0);
> > +	if (irq < 0) {
> > +		dev_err(&pdev->dev, "can't get irq number\n");
> > +		return irq;
> > +	}
> > +
> > +	lpi2c_imx->adapter.owner	= THIS_MODULE;
> > +	lpi2c_imx->adapter.algo		= &lpi2c_imx_algo;
> > +	lpi2c_imx->adapter.dev.parent	= &pdev->dev;
> > +	lpi2c_imx->adapter.dev.of_node	= pdev->dev.of_node;
> > +	strlcpy(lpi2c_imx->adapter.name, pdev->name,
> > +				sizeof(lpi2c_imx->adapter.name));
> 
> checkpatch --strict complains:
> 
> CHECK: Alignment should match open parenthesis
> #630: FILE: drivers/i2c/busses/i2c-imx-lpi2c.c:578:
> +       strlcpy(lpi2c_imx->adapter.name, pdev->name,
> +                               sizeof(lpi2c_imx->adapter.name));

Thanks, will change it in next version. 

> > +
> > +	lpi2c_imx->clk = devm_clk_get(&pdev->dev, NULL);
> > +	if (IS_ERR(lpi2c_imx->clk)) {
> > +		dev_err(&pdev->dev, "can't get I2C peripheral clock\n");
> > +		return PTR_ERR(lpi2c_imx->clk);
> > +	}
> > +
> > +	ret = clk_prepare(lpi2c_imx->clk);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "clk prepare failed %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = of_property_read_u32(pdev->dev.of_node,
> > +				   "clock-frequency", &lpi2c_imx->bitrate);
> > +	if (ret)
> > +		lpi2c_imx->bitrate = LPI2C_DEFAULT_RATE;
> > +
> > +	ret = devm_request_irq(&pdev->dev, irq, lpi2c_imx_isr, 0,
> > +				pdev->name, lpi2c_imx);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "can't claim irq %d\n", irq);
> > +		return ret;
> 
> On error path you leak clk_prepare()'d lpi2c_imx->clk clock.
> 
> I would recommend to prepare the clock after successful adapter registration.

Thanks!  But  it's better that clk is prepared  before adapter registration.  Because during adapter registration,  i2c slave will probe. 
As a result,  i2c xfer will be called. In such situation, clk_enable() is called while clk has not been prepared.

> > +	}
> > +
> > +	i2c_set_adapdata(&lpi2c_imx->adapter, lpi2c_imx);
> > +	platform_set_drvdata(pdev, lpi2c_imx);
> > +
> > +	ret = i2c_add_adapter(&lpi2c_imx->adapter);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "registration failed\n");
> 
> Please remove this notification line, it is reported by I2C core.

Thanks, will remove it in next version. 

> > +		return ret;
> > +	}
> > +
> > +	dev_info(&lpi2c_imx->adapter.dev, "LPI2C adapter registered\n");
> > +
> > +	return 0;
> > +}
> > +
> > +static int lpi2c_imx_remove(struct platform_device *pdev) {
> > +	struct lpi2c_imx_struct *lpi2c_imx = platform_get_drvdata(pdev);
> > +
> 
> Missing clk_unprepare(lpi2c_imx->clk clock);

Yes,  you are right. Thanks. 

> > +	i2c_del_adapter(&lpi2c_imx->adapter);
> > +
> > +	return 0;
> > +}
> > +
> > +static struct platform_driver lpi2c_imx_driver = {
> > +	.probe = lpi2c_imx_probe,
> > +	.remove = lpi2c_imx_remove,
> > +	.driver = {
> > +		.name = DRIVER_NAME,
> > +		.of_match_table = lpi2c_imx_of_match,
> > +	},
> > +};
> > +
> > +module_platform_driver(lpi2c_imx_driver);
> > +
> > +MODULE_AUTHOR("Gao Pan <pandy.gao@nxp.com>");
> MODULE_DESCRIPTION("I2C
> > +adapter driver for LPI2C bus"); MODULE_LICENSE("GPL v2");


Thanks again for your valuable comments!

Best  Regard
Gao Pan

RE: [Patch V4 2/2] i2c: imx: add devicetree binding for lpi2c

[Pandy Gao]

 From: Vladimir Zapolskiy <mailto:vz@mleia.com>  Sent: Thursday, November 17, 2016 8:32 AM
> To: Pandy Gao <pandy.gao@nxp.com>; wsa@the-dreams.de; u.kleine-
> koenig@pengutronix.de; cmo@melexis.com; robh@kernel.org
> Cc: linux-i2c@vger.kernel.org; Frank Li <frank.li@nxp.com>; Andy Duan
> <fugang.duan@nxp.com>
> Subject: Re: [Patch V4 2/2] i2c: imx: add devicetree binding for lpi2c
> 
> On 11/14/2016 11:23 AM, Gao Pan wrote:
> > Add a binding document for lpi2c driver
> >
> > Signed-off-by: Gao Pan <pandy.gao@nxp.com>
> > ---
> >  .../devicetree/bindings/i2c/i2c-imx-lpi2c.txt        | 20
> ++++++++++++++++++++
> >  1 file changed, 20 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-imx-lpi2c.txt
> > b/Documentation/devicetree/bindings/i2c/i2c-imx-lpi2c.txt
> > new file mode 100644
> > index 0000000..edaf04f
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-imx-lpi2c.txt
> > @@ -0,0 +1,20 @@
> > +* Freescale Low Power Inter IC (LPI2C) for i.MX
> > +
> > +Required properties:
> > +- compatible :
> > +  - "fsl,imx8dv-lpi2c" for LPI2C compatible with the one integrated
> > +on i.MX8DV soc
> > +  - "fsl,imx7ulp-lpi2c" for LPI2C compatible with the one integrated
> > +on i.MX7ULP soc
> > +- reg : address and length of the lpi2c master registers
> > +- interrupt-parent : core interrupt controller
> > +- interrupts : lpi2c interrupt
> > +- clocks : lpi2c clock specifier
> 
> I don't know if description of standard properties is really needed, probably
> Rob can advise.
> 
> My point is that pretty "interrupts-extended" is never mentioned, and all three
> interrupt* properties are well described in interrupts.txt, and in general there is
> no point to mention all those interrupts, clocks, clock-names and friends
> properties again and again.
> 
> But here better to get a clarification from Rob.

Thanks. 

> > +
> > +Examples:
> > +
> > +lpi2c7: lpi2c7@40A50000 {
> > +	compatible = "fsl,imx8dv-lpi2c";
> > +	reg = <0x40A50000 0x10000>;
> > +	interrupt-parent = <&intc>;
> > +	interrupts = <GIC_SPI 37 IRQ_TYPE_LEVEL_HIGH>;
> > +	clocks = <&clks IMX7ULP_CLK_LPI2C7>; };
> >
> 
> Please rearrange the changes, devicetree binding change should be 1/2, the
> driver change should be 2/2.

Thanks, will change it in next version.

Best Regards
Gao Pan