[PATCH v1 1/3] dt: bindings: add documentation for zx2967 family i2c controller

[PATCH v1 1/3] dt: bindings: add documentation for zx2967 family i2c controller

[Baoyou Xie]

This patch adds dt-binding documentation for zx2967 family
i2c controller.

Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
---
 .../devicetree/bindings/i2c/i2c-zx2967.txt         | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/i2c-zx2967.txt

diff --git a/Documentation/devicetree/bindings/i2c/i2c-zx2967.txt b/Documentation/devicetree/bindings/i2c/i2c-zx2967.txt
new file mode 100644
index 0000000..cb806d1
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-zx2967.txt
@@ -0,0 +1,22 @@
+ZTE zx2967 I2C controller
+
+Required properties:
+ - compatible: must be "zte,zx296718-i2c"
+ - reg: physical address and length of the device registers
+ - interrupts: a single interrupt specifier
+ - clocks: clock for the device
+ - #address-cells: should be <1>
+ - #size-cells: should be <0>
+ - clock-frequency: the desired I2C bus clock frequency.
+
+Examples:
+
+	i2c@112000 {
+		compatible = "zte,zx296718-i2c";
+		reg = <0x00112000 0x1000>;
+		interrupts = <GIC_SPI 112 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&osc24m>;
+		#address-cells = <1>
+		#size-cells = <0>;
+		clock-frequency = <1600000>;
+	};
-- 
2.7.4

[PATCH v1 2/3] MAINTAINERS: add zx2967 i2c controller driver to ARM ZTE architecture

[Baoyou Xie]

Add the zx2967 i2c controller driver as maintained by ARM ZTE
architecture maintainers, as they're parts of the core IP.

Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
---
 MAINTAINERS | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 275c434..757c098 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1987,12 +1987,14 @@ L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 S:	Maintained
 F:	arch/arm/mach-zx/
 F:	drivers/clk/zte/
+F:	drivers/i2c/busses/i2c-zx2967.c
 F:	drivers/reset/reset-zx2967.c
 F:	drivers/soc/zte/
 F:	drivers/thermal/zx*
 F:	drivers/watchdog/zx2967_wdt.c
 F:	Documentation/devicetree/bindings/arm/zte.txt
 F:	Documentation/devicetree/bindings/clock/zx296702-clk.txt
+F:	Documentation/devicetree/bindings/i2c/i2c-zx2967.txt
 F:	Documentation/devicetree/bindings/reset/zte,zx2967-reset.txt
 F:	Documentation/devicetree/bindings/soc/zte/
 F:	Documentation/devicetree/bindings/thermal/zx*
-- 
2.7.4

[PATCH v1 3/3] i2c: zx2967: add i2c controller driver for ZTE's zx2967 family

[Baoyou Xie]

This patch adds i2c controller driver for ZTE's zx2967 family.

Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
---
 drivers/i2c/busses/Kconfig      |   8 +
 drivers/i2c/busses/Makefile     |   1 +
 drivers/i2c/busses/i2c-zx2967.c | 645 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 654 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-zx2967.c

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index e4a603e..946d2b0 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -1246,4 +1246,12 @@ config I2C_OPAL
 	  This driver can also be built as a module. If so, the module will be
 	  called as i2c-opal.
 
+config I2C_ZX2967
+	bool "ZTE zx2967 I2C support"
+	depends on ARCH_ZX
+	default y
+	help
+	  Selecting this option will add ZX I2C driver.
+	  If unsure, say y.
+
 endmenu
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index beb4809..16b2901 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -101,6 +101,7 @@ obj-$(CONFIG_I2C_XILINX)	+= i2c-xiic.o
 obj-$(CONFIG_I2C_XLR)		+= i2c-xlr.o
 obj-$(CONFIG_I2C_XLP9XX)	+= i2c-xlp9xx.o
 obj-$(CONFIG_I2C_RCAR)		+= i2c-rcar.o
+obj-$(CONFIG_I2C_ZX2967)	+= i2c-zx2967.o
 
 # External I2C/SMBus adapter drivers
 obj-$(CONFIG_I2C_DIOLAN_U2C)	+= i2c-diolan-u2c.o
diff --git a/drivers/i2c/busses/i2c-zx2967.c b/drivers/i2c/busses/i2c-zx2967.c
new file mode 100644
index 0000000..6c2145b
--- /dev/null
+++ b/drivers/i2c/busses/i2c-zx2967.c
@@ -0,0 +1,645 @@
+/*
+ * ZTE's zx2967 family i2c bus controller driver
+ *
+ * Copyright (C) 2017 ZTE Ltd.
+ *
+ * Author: Baoyou Xie <baoyou.xie@linaro.org>
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/platform_device.h>
+
+#define BW1				(u32)1
+
+#define REG_CMD				0x04
+#define REG_DEVADDR_H			0x0C
+#define REG_DEVADDR_L			0x10
+#define REG_CLK_DIV_FS			0x14
+#define REG_CLK_DIV_HS			0x18
+#define REG_WRCONF			0x1C
+#define REG_RDCONF			0x20
+#define REG_DATA			0x24
+#define REG_STAT			0x28
+
+#define I2C_STOP			0
+#define I2C_MASTER			(1 << 0)
+#define I2C_ADDR_MODE_TEN		(1 << 1)
+#define I2C_IRQ_MSK_ENABLE		(1 << 3)
+#define I2C_RW_READ			(1 << 4)
+#define I2C_CMB_RW_EN			(1 << 5)
+#define I2C_START			(1 << 6)
+#define I2C_ADDR_MODE_TEN		(1 << 1)
+
+#define I2C_WFIFO_RESET			(1 << 7)
+#define I2C_RFIFO_RESET			(1 << 7)
+
+#define I2C_IRQ_ACK_CLEAR		(1 << 7)
+#define I2C_INT_MASK			0x3f
+
+#define I2C_TRANS_DONE			(1 << 0)
+#define I2C_ERROR_DEVICE		(1 << 1)
+#define I2C_ERROR_DATA			(1 << 2)
+#define I2C_ERROR_MASK			(I2C_ERROR_DATA | I2C_ERROR_DEVICE)
+
+#define I2C_SR_BUSY			(1 << 6)
+
+#define I2C_SR_EDEVICE			(1 << 1)
+#define I2C_SR_EDATA			(1 << 2)
+
+#define I2C_FIFO_MAX			16
+
+#define I2C_TIMEOUT			msecs_to_jiffies(1000)
+
+struct zx2967_i2c_info {
+	spinlock_t		lock;
+	struct device		*dev;
+	struct i2c_adapter	adap;
+	struct clk		*clk;
+	struct completion	complete;
+	u32			clk_freq;
+	struct pinctrl		*pin_scl;
+	struct pinctrl		*pin_sda;
+	void __iomem		*reg_base;
+	size_t			residue;
+	int			id;
+	int			irq;
+	int			msg_rd;
+	u8			*buf;
+	u8			access_cnt;
+	bool			is_suspended;
+};
+
+static void zx2967_i2c_writel(struct zx2967_i2c_info *zx_i2c,
+			      u32 val, unsigned long reg)
+{
+	writel_relaxed(val, zx_i2c->reg_base + reg);
+}
+
+static u32 zx2967_i2c_readl(struct zx2967_i2c_info *zx_i2c, unsigned long reg)
+{
+	return readl_relaxed(zx_i2c->reg_base + reg);
+}
+
+static void zx2967_i2c_writesb(struct zx2967_i2c_info *zx_i2c,
+			       void *data, unsigned long reg, int len)
+{
+	writesb(zx_i2c->reg_base + reg, data, len);
+}
+
+static void zx2967_i2c_readsb(struct zx2967_i2c_info *zx_i2c,
+			      void *data, unsigned long reg, int len)
+{
+	readsb(zx_i2c->reg_base + reg, data, len);
+}
+
+static void zx2967_i2c_start_ctrl(struct zx2967_i2c_info *zx_i2c)
+{
+	u32 status;
+	u32 ctl;
+
+	status = zx2967_i2c_readl(zx_i2c, REG_STAT);
+	status |= I2C_IRQ_ACK_CLEAR;
+	zx2967_i2c_writel(zx_i2c, status, REG_STAT);
+
+	ctl = zx2967_i2c_readl(zx_i2c, REG_CMD);
+	if (zx_i2c->msg_rd)
+		ctl |= I2C_RW_READ;
+	else
+		ctl &= ~I2C_RW_READ;
+	ctl &= ~I2C_CMB_RW_EN;
+	ctl |= I2C_START;
+	zx2967_i2c_writel(zx_i2c, ctl, REG_CMD);
+}
+
+static int zx2967_i2c_flush_fifos(struct zx2967_i2c_info *zx_i2c)
+{
+	u32 val = 0;
+	u32 offset = 0;
+
+	if (zx_i2c->msg_rd) {
+		offset = REG_RDCONF;
+		val = I2C_RFIFO_RESET;
+	} else {
+		offset = REG_WRCONF;
+		val = I2C_WFIFO_RESET;
+	}
+
+	val |= zx2967_i2c_readl(zx_i2c, offset);
+	zx2967_i2c_writel(zx_i2c, val, offset);
+
+	return 0;
+}
+
+static int zx2967_i2c_empty_rx_fifo(struct zx2967_i2c_info *zx_i2c, u32 size)
+{
+	u8  val[I2C_FIFO_MAX] = {0};
+	int i = 0;
+
+	if (size == 0) {
+		dev_err(zx_i2c->dev, "size is invalid\n");
+		return -EINVAL;
+	}
+
+	zx2967_i2c_readsb(zx_i2c, val, REG_DATA, size);
+	for (i = 0; i < size; i++) {
+		*(zx_i2c->buf++) = val[i];
+		zx_i2c->residue--;
+		if (zx_i2c->residue <= 0)
+			break;
+	}
+
+	barrier();
+
+	return 0;
+}
+
+static int zx2967_i2c_fill_tx_fifo(struct zx2967_i2c_info *zx_i2c)
+{
+	u8 *buf = zx_i2c->buf;
+	size_t residue = zx_i2c->residue;
+
+	if (residue == 0) {
+		dev_err(zx_i2c->dev, "residue is %d\n", (int)residue);
+		return -EINVAL;
+	}
+
+	if (residue <= I2C_FIFO_MAX) {
+		zx2967_i2c_writesb(zx_i2c, buf, REG_DATA, residue);
+
+		/* Again update before writing to FIFO to make sure isr sees. */
+		zx_i2c->residue = 0;
+		zx_i2c->buf = NULL;
+	} else {
+		zx2967_i2c_writesb(zx_i2c, buf, REG_DATA, I2C_FIFO_MAX);
+		zx_i2c->residue -= I2C_FIFO_MAX;
+		zx_i2c->buf += I2C_FIFO_MAX;
+	}
+
+	barrier();
+
+	return 0;
+}
+
+static int zx2967_i2c_reset_hardware(struct zx2967_i2c_info *zx_i2c)
+{
+	u32 val;
+	u32 clk_div;
+	u32 status;
+
+	val = I2C_MASTER | I2C_IRQ_MSK_ENABLE;
+	zx2967_i2c_writel(zx_i2c, val, REG_CMD);
+
+	clk_div = clk_get_rate(zx_i2c->clk) / zx_i2c->clk_freq - 1;
+	zx2967_i2c_writel(zx_i2c, clk_div, REG_CLK_DIV_FS);
+	zx2967_i2c_writel(zx_i2c, clk_div, REG_CLK_DIV_HS);
+
+	zx2967_i2c_writel(zx_i2c, I2C_FIFO_MAX - 1, REG_WRCONF);
+	zx2967_i2c_writel(zx_i2c, I2C_FIFO_MAX - 1, REG_RDCONF);
+	zx2967_i2c_writel(zx_i2c, 1, REG_RDCONF);
+
+	if (zx2967_i2c_flush_fifos(zx_i2c))
+		return -ETIMEDOUT;
+
+	status = zx2967_i2c_readl(zx_i2c, REG_STAT);
+	if (status & (I2C_SR_BUSY))
+		return -EBUSY;
+	if (status & (I2C_SR_EDEVICE | I2C_SR_EDATA))
+		return -EIO;
+
+	enable_irq(zx_i2c->irq);
+
+	return 0;
+}
+
+static void zx2967_i2c_isr_clr(struct zx2967_i2c_info *zx_i2c)
+{
+	u32 status;
+
+	status = zx2967_i2c_readl(zx_i2c, REG_STAT);
+	status |= I2C_IRQ_ACK_CLEAR;
+	zx2967_i2c_writel(zx_i2c, status, REG_STAT);
+}
+
+static irqreturn_t zx2967_i2c_isr(int irq, void *dev_id)
+{
+	u32 status;
+	struct zx2967_i2c_info *zx_i2c = (struct zx2967_i2c_info *)dev_id;
+	unsigned long flags;
+
+	spin_lock_irqsave(&zx_i2c->lock, flags);
+
+	status = zx2967_i2c_readl(zx_i2c, REG_STAT) & I2C_INT_MASK;
+	zx2967_i2c_isr_clr(zx_i2c);
+
+	if (status & I2C_ERROR_MASK) {
+		spin_unlock_irqrestore(&zx_i2c->lock, flags);
+		return IRQ_HANDLED;
+	}
+
+	if (status & I2C_TRANS_DONE)
+		complete(&zx_i2c->complete);
+
+	spin_unlock_irqrestore(&zx_i2c->lock, flags);
+
+	return IRQ_HANDLED;
+}
+
+static void  zx2967_enable_tenbit(struct zx2967_i2c_info *zx_i2c, __u16 addr)
+{
+	u16 val = ((addr >> 7) & 0x7);
+
+	if (val > 0) {
+		zx2967_i2c_writel(zx_i2c, val, REG_DEVADDR_H);
+		val = (zx2967_i2c_readl(zx_i2c, REG_CMD)) | I2C_ADDR_MODE_TEN;
+		zx2967_i2c_writel(zx_i2c, val, REG_CMD);
+	}
+}
+
+static int zx2967_i2c_xfer_msg(struct zx2967_i2c_info *zx_i2c,
+			       struct i2c_msg *msg)
+{
+	unsigned long time_left = 0;
+	unsigned int i = 0;
+
+	if (msg->len == 0)
+		return -EINVAL;
+
+	zx2967_i2c_flush_fifos(zx_i2c);
+
+	zx_i2c->buf = msg->buf;
+	zx_i2c->residue = msg->len;
+	zx_i2c->access_cnt = msg->len / I2C_FIFO_MAX;
+	zx_i2c->msg_rd = (msg->flags & I2C_M_RD);
+
+	if (zx_i2c->msg_rd) {
+		for (i = 0; i < zx_i2c->access_cnt; i++) {
+			reinit_completion(&zx_i2c->complete);
+			zx2967_i2c_writel(zx_i2c, I2C_FIFO_MAX - 1,
+					  REG_RDCONF);
+			zx2967_i2c_start_ctrl(zx_i2c);
+
+			time_left = wait_for_completion_timeout(
+					&zx_i2c->complete, I2C_TIMEOUT);
+			if (time_left == 0) {
+				dev_err(zx_i2c->dev,
+					"read i2c transfer timed out\n");
+				disable_irq(zx_i2c->irq);
+				zx2967_i2c_reset_hardware(zx_i2c);
+				return -EIO;
+			}
+
+			zx2967_i2c_empty_rx_fifo(zx_i2c, I2C_FIFO_MAX);
+		}
+
+		if (zx_i2c->residue < I2C_FIFO_MAX) {
+			reinit_completion(&zx_i2c->complete);
+			zx2967_i2c_writel(zx_i2c, zx_i2c->residue - 1,
+					  REG_RDCONF);
+			zx2967_i2c_start_ctrl(zx_i2c);
+			time_left = wait_for_completion_timeout(
+					&zx_i2c->complete, I2C_TIMEOUT);
+			if (time_left == 0) {
+				dev_err(zx_i2c->dev,
+					"read i2c transfer timed out\n");
+				disable_irq(zx_i2c->irq);
+				zx2967_i2c_reset_hardware(zx_i2c);
+				return -EIO;
+			}
+
+			zx2967_i2c_empty_rx_fifo(zx_i2c, zx_i2c->residue);
+		}
+
+		zx_i2c->residue = 0;
+		zx_i2c->access_cnt = 0;
+	} else {
+		reinit_completion(&zx_i2c->complete);
+		zx2967_i2c_fill_tx_fifo(zx_i2c);
+		zx2967_i2c_start_ctrl(zx_i2c);
+
+		for (i = 0; i < zx_i2c->access_cnt; i++) {
+			time_left = wait_for_completion_timeout(
+					&zx_i2c->complete, I2C_TIMEOUT);
+			if (time_left == 0) {
+				dev_err(zx_i2c->dev,
+					"write i2c transfer timed out\n");
+				disable_irq(zx_i2c->irq);
+				zx2967_i2c_reset_hardware(zx_i2c);
+				return -EIO;
+			}
+
+			if (zx_i2c->residue != 0) {
+				reinit_completion(&zx_i2c->complete);
+				zx2967_i2c_fill_tx_fifo(zx_i2c);
+				zx2967_i2c_start_ctrl(zx_i2c);
+			}
+		}
+	}
+
+	return 0;
+}
+
+static int zx2967_i2c_xfer(struct i2c_adapter *adap,
+			   struct i2c_msg *msgs, int num)
+{
+	int i;
+	int ret = 0;
+	struct zx2967_i2c_info *zx_i2c = i2c_get_adapdata(adap);
+
+	if (zx_i2c->is_suspended)
+		return -EBUSY;
+
+	zx2967_i2c_writel(zx_i2c, (msgs->addr & 0x7f), REG_DEVADDR_L);
+	zx2967_i2c_writel(zx_i2c, (msgs->addr >> 7) & 0x7, REG_DEVADDR_H);
+	if (zx2967_i2c_readl(zx_i2c, REG_DEVADDR_H) > 0)
+		zx2967_enable_tenbit(zx_i2c, msgs->addr);
+
+	for (i = 0; i < num; i++) {
+		ret = zx2967_i2c_xfer_msg(zx_i2c, &msgs[i]);
+		if (num > 1)
+			usleep_range(1000, 2000);
+		if (ret)
+			break;
+	}
+
+	return ret ?: i;
+}
+
+static int zx2967_smbus_xfer(struct i2c_adapter *adap, u16 addr,
+			     unsigned short flags, char read_write,
+			     u8 command, int size, union i2c_smbus_data *data)
+{
+	struct zx2967_i2c_info *zx_i2c = i2c_get_adapdata(adap);
+	u32 val;
+	u8 buf[2];
+	unsigned long time_left;
+
+	val = zx2967_i2c_readl(zx_i2c, REG_RDCONF);
+	val |= I2C_RFIFO_RESET;
+	zx2967_i2c_writel(zx_i2c, val, REG_RDCONF);
+	zx2967_i2c_writel(zx_i2c, (addr & 0x7f), REG_DEVADDR_L);
+
+	zx2967_enable_tenbit(zx_i2c, addr);
+	val = zx2967_i2c_readl(zx_i2c, REG_CMD);
+	val &= ~I2C_RW_READ;
+	zx2967_i2c_writel(zx_i2c, val, REG_CMD);
+
+	switch (size) {
+	case I2C_SMBUS_QUICK:
+		read_write = I2C_SMBUS_WRITE;
+		break;
+	case I2C_SMBUS_BYTE:
+		zx2967_i2c_writel(zx_i2c, command, REG_DATA);
+		break;
+	case I2C_SMBUS_BYTE_DATA:
+		zx2967_i2c_writel(zx_i2c, command, REG_DATA);
+
+		if (read_write == I2C_SMBUS_WRITE)
+			zx2967_i2c_writel(zx_i2c, data->byte, REG_DATA);
+
+		break;
+	case I2C_SMBUS_WORD_DATA:
+		zx2967_i2c_writel(zx_i2c, command, REG_DATA);
+		zx2967_i2c_writel(zx_i2c, (data->word & 0xff), REG_DATA);
+
+		if (read_write == I2C_SMBUS_WRITE) {
+			zx2967_i2c_writel(zx_i2c, (data->word >> 8), REG_DATA);
+			zx2967_i2c_writel(zx_i2c,
+				(data->word & 0xff), REG_DATA);
+		}
+		break;
+
+	default:
+		dev_warn(&adap->dev, "Unsupported transaction %d\n", size);
+		return -EOPNOTSUPP;
+	}
+
+	if (read_write == I2C_SMBUS_WRITE) {
+		reinit_completion(&zx_i2c->complete);
+		val = zx2967_i2c_readl(zx_i2c, REG_CMD);
+		val |= I2C_START;
+		zx2967_i2c_writel(zx_i2c, val, REG_CMD);
+
+		time_left = wait_for_completion_timeout(
+				&zx_i2c->complete, I2C_TIMEOUT);
+		if (time_left == 0) {
+			dev_err(zx_i2c->dev, "i2c write transfer timed out\n");
+			disable_irq(zx_i2c->irq);
+			zx2967_i2c_reset_hardware(zx_i2c);
+			return -EIO;
+		}
+
+		return 0;
+	}
+
+	reinit_completion(&zx_i2c->complete);
+
+	val = zx2967_i2c_readl(zx_i2c, REG_CMD);
+	val |= I2C_CMB_RW_EN;
+	zx2967_i2c_writel(zx_i2c, val, REG_CMD);
+
+	val = zx2967_i2c_readl(zx_i2c, REG_CMD);
+	val |= I2C_START;
+	zx2967_i2c_writel(zx_i2c, val, REG_CMD);
+
+	time_left = wait_for_completion_timeout(&zx_i2c->complete,
+				I2C_TIMEOUT);
+	if (time_left == 0) {
+		dev_err(zx_i2c->dev, "i2c read transfer timed out\n");
+		disable_irq(zx_i2c->irq);
+		zx2967_i2c_reset_hardware(zx_i2c);
+		return -EIO;
+	}
+
+	usleep_range(1000, 2000);
+	switch (size) {
+	case I2C_SMBUS_BYTE:
+	case I2C_SMBUS_BYTE_DATA:
+		val = zx2967_i2c_readl(zx_i2c, REG_DATA);
+		data->byte = val;
+		break;
+	case I2C_SMBUS_WORD_DATA:
+	case I2C_SMBUS_PROC_CALL:
+		buf[0] = zx2967_i2c_readl(zx_i2c, REG_DATA);
+		buf[1] = zx2967_i2c_readl(zx_i2c, REG_DATA);
+		data->word = (buf[0] << 8) | buf[1];
+		break;
+	default:
+		dev_warn(&adap->dev, "Unsupported transaction %d\n", size);
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static u32 zx2967_i2c_func(struct i2c_adapter *adap)
+{
+	return 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_PROC_CALL |
+	       I2C_FUNC_I2C | I2C_FUNC_SMBUS_I2C_BLOCK;
+}
+
+#ifdef	CONFIG_PM
+static int zx2967_i2c_suspend(struct device *dev)
+{
+	struct zx2967_i2c_info *zx_i2c = dev_get_drvdata(dev);
+
+	zx_i2c->is_suspended = true;
+	if (__clk_get_enable_count(zx_i2c->clk) == 1)
+		clk_disable_unprepare(zx_i2c->clk);
+
+	return 0;
+}
+
+static int zx2967_i2c_resume(struct device *dev)
+{
+	struct zx2967_i2c_info *zx_i2c = dev_get_drvdata(dev);
+
+	zx_i2c->is_suspended = false;
+	clk_prepare_enable(zx_i2c->clk);
+
+	return 0;
+}
+static const struct dev_pm_ops zx2967_i2c_dev_pm_ops = {
+	.suspend	= zx2967_i2c_suspend,
+	.resume		= zx2967_i2c_resume,
+};
+#define ZX2967_I2C_DEV_PM_OPS (&zx2967_i2c_dev_pm_ops)
+#else
+#define	ZX2967_I2C_DEV_PM_OPS	NULL
+#endif
+
+static const struct i2c_algorithm zx2967_i2c_algo = {
+	.master_xfer = zx2967_i2c_xfer,
+	.smbus_xfer = zx2967_smbus_xfer,
+	.functionality = zx2967_i2c_func,
+};
+
+static const struct of_device_id zx2967_i2c_of_match[] = {
+	{ .compatible = "zte,zx296718-i2c", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, zx2967_i2c_of_match);
+
+static int zx2967_i2c_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct zx2967_i2c_info *zx_i2c = NULL;
+	struct clk *clk;
+	void __iomem *reg_base;
+	int ret = 0;
+
+	zx_i2c = devm_kzalloc(&pdev->dev, sizeof(*zx_i2c), GFP_KERNEL);
+	if (!zx_i2c)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "missing io resource\n");
+		return -EINVAL;
+	}
+
+	reg_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(reg_base))
+		return PTR_ERR(reg_base);
+
+	clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "missing controller clock");
+		return PTR_ERR(clk);
+	}
+
+	ret = clk_prepare_enable(clk);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to enable i2c_clk\n");
+		return ret;
+	}
+
+	of_property_read_u32(pdev->dev.of_node,
+			"clock-frequency", &zx_i2c->clk_freq);
+	zx_i2c->reg_base = reg_base;
+	zx_i2c->clk = clk;
+	zx_i2c->irq = platform_get_irq(pdev, 0);
+	zx_i2c->id = pdev->id;
+	zx_i2c->dev = &pdev->dev;
+
+	zx_i2c->pin_scl = devm_pinctrl_get_select(&pdev->dev, "scl");
+	if (IS_ERR(zx_i2c->pin_scl))
+		dev_info(&pdev->dev, "scl pin is not specified in dts\n");
+
+	zx_i2c->pin_sda = devm_pinctrl_get_select(&pdev->dev, "sda");
+	if (IS_ERR(zx_i2c->pin_sda))
+		dev_info(&pdev->dev, "sda pin is not specified in dts\n");
+
+	spin_lock_init(&zx_i2c->lock);
+	init_completion(&zx_i2c->complete);
+	platform_set_drvdata(pdev, zx_i2c);
+
+	ret = zx2967_i2c_reset_hardware(zx_i2c);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to initialize i2c controller\n");
+		goto unprepare_clk;
+	}
+
+	ret = devm_request_irq(&pdev->dev, zx_i2c->irq,
+			zx2967_i2c_isr, 0, dev_name(&pdev->dev), zx_i2c);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to request irq %i\n", zx_i2c->irq);
+		goto unprepare_clk;
+	}
+
+	i2c_set_adapdata(&zx_i2c->adap, zx_i2c);
+	zx_i2c->adap.owner = THIS_MODULE;
+	zx_i2c->adap.class = I2C_CLASS_DEPRECATED;
+	strlcpy(zx_i2c->adap.name, "zx2967 i2c adapter",
+		sizeof(zx_i2c->adap.name));
+	zx_i2c->adap.algo = &zx2967_i2c_algo;
+	zx_i2c->adap.dev.parent = &pdev->dev;
+	zx_i2c->adap.nr = pdev->id;
+	zx_i2c->adap.dev.of_node = pdev->dev.of_node;
+
+	ret = i2c_add_numbered_adapter(&zx_i2c->adap);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to add zx2967 i2c adapter\n");
+		goto unprepare_clk;
+	}
+
+	return 0;
+
+unprepare_clk:
+	clk_unprepare(zx_i2c->clk);
+	return ret;
+}
+
+static int zx2967_i2c_remove(struct platform_device *pdev)
+{
+	struct zx2967_i2c_info *zx_i2c = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&zx_i2c->adap);
+	clk_unprepare(zx_i2c->clk);
+
+	return 0;
+}
+
+static struct platform_driver zx2967_i2c_driver = {
+	.probe	= zx2967_i2c_probe,
+	.remove	= zx2967_i2c_remove,
+	.driver	= {
+		.name  = "zx2967_i2c",
+		.of_match_table = zx2967_i2c_of_match,
+		.pm		= ZX2967_I2C_DEV_PM_OPS,
+	},
+};
+module_platform_driver(zx2967_i2c_driver);
+
+MODULE_AUTHOR("Baoyou Xie <baoyou.xie@linaro.org>");
+MODULE_DESCRIPTION("ZTE zx2967 I2C Bus Controller driver");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4

Re: [PATCH v1 3/3] i2c: zx2967: add i2c controller driver for ZTE's zx2967 family

[Andy Shevchenko]

On Fri, Jan 20, 2017 at 10:43 AM, Baoyou Xie <baoyou.xie@linaro.org> wrote:
> This patch adds i2c controller driver for ZTE's zx2967 family.
>

> +config I2C_ZX2967
> +       bool "ZTE zx2967 I2C support"

No module?

> +       depends on ARCH_ZX
> +       default y

Would architecture selects it instead?

> +       help
> +         Selecting this option will add ZX I2C driver.
> +         If unsure, say y.

Two sentences about the same in spite 'default y'.

> +#define BW1                            (u32)1

Do you really need casting?

> +#define I2C_STOP                       0
> +#define I2C_MASTER                     (1 << 0)

BIT(0) ?
And so further.

> +#define I2C_INT_MASK                   0x3f

GENMASK(6, 0) ?


> +#define I2C_ERROR_MASK                 (I2C_ERROR_DATA | I2C_ERROR_DEVICE)

Ditto.
GENMASK() with explicit numbers.

> +static int zx2967_i2c_flush_fifos(struct zx2967_i2c_info *zx_i2c)
> +{
> +       u32 val = 0;
> +       u32 offset = 0;

Useless assignments.

> +
> +       if (zx_i2c->msg_rd) {
> +               offset = REG_RDCONF;
> +               val = I2C_RFIFO_RESET;
> +       } else {
> +               offset = REG_WRCONF;
> +               val = I2C_WFIFO_RESET;
> +       }

> +static int zx2967_i2c_empty_rx_fifo(struct zx2967_i2c_info *zx_i2c, u32 size)
> +{

> +       u8  val[I2C_FIFO_MAX] = {0};
> +       int i = 0;

Ditto.

> +
> +       if (size == 0) {

Would it be the case?

> +               dev_err(zx_i2c->dev, "size is invalid\n");
> +               return -EINVAL;
> +       }

And what happens even in that case if you just remove this check?

> +
> +       zx2967_i2c_readsb(zx_i2c, val, REG_DATA, size);
> +       for (i = 0; i < size; i++) {
> +               *(zx_i2c->buf++) = val[i];
> +               zx_i2c->residue--;
> +               if (zx_i2c->residue <= 0)
> +                       break;

> +static int zx2967_i2c_fill_tx_fifo(struct zx2967_i2c_info *zx_i2c)
> +{
> +       u8 *buf = zx_i2c->buf;
> +       size_t residue = zx_i2c->residue;
> +
> +       if (residue == 0) {
> +               dev_err(zx_i2c->dev, "residue is %d\n", (int)residue);
> +               return -EINVAL;
> +       }

Ditto.


> +static void  zx2967_enable_tenbit(struct zx2967_i2c_info *zx_i2c, __u16 addr)
> +{
> +       u16 val = ((addr >> 7) & 0x7);

Redundant parens.

> +       if (val > 0) {

if (!val)
 return;

> +static int zx2967_i2c_xfer_msg(struct zx2967_i2c_info *zx_i2c,
> +                              struct i2c_msg *msg
> +{
> +       unsigned long time_left = 0;

> +       unsigned int i = 0;

Redundant assignment.

> +
> +       if (msg->len == 0)

if (!msg...)

> +               return -EINVAL;

> +static int zx2967_i2c_xfer(struct i2c_adapter *adap,
> +                          struct i2c_msg *msgs, int num)
> +{
> +       int i;

> +       int ret = 0;

Redundant. See below.

> +       struct zx2967_i2c_info *zx_i2c = i2c_get_adapdata(adap);

Reverse tree, please.

> +
> +       if (zx_i2c->is_suspended)
> +               return -EBUSY;
> +
> +       zx2967_i2c_writel(zx_i2c, (msgs->addr & 0x7f), REG_DEVADDR_L);
> +       zx2967_i2c_writel(zx_i2c, (msgs->addr >> 7) & 0x7, REG_DEVADDR_H);
> +       if (zx2967_i2c_readl(zx_i2c, REG_DEVADDR_H) > 0)
> +               zx2967_enable_tenbit(zx_i2c, msgs->addr);
> +
> +       for (i = 0; i < num; i++) {

int ret;

> +               ret = zx2967_i2c_xfer_msg(zx_i2c, &msgs[i]);
> +               if (num > 1)
> +                       usleep_range(1000, 2000);
> +               if (ret)

> +                       break;

return ret;

> +       }
> +

> +       return ret ?: i;

return i;

And looking now, how i can't be num here?

> +}

> +{
> +       struct zx2967_i2c_info *zx_i2c = i2c_get_adapdata(adap);

> +       u32 val;
> +       u8 buf[2];
> +       unsigned long time_left;

Reverse tree.

> +       usleep_range(1000, 2000);
> +       switch (size) {
> +       case I2C_SMBUS_BYTE:
> +       case I2C_SMBUS_BYTE_DATA:
> +               val = zx2967_i2c_readl(zx_i2c, REG_DATA);
> +               data->byte = val;
> +               break;
> +       case I2C_SMBUS_WORD_DATA:
> +       case I2C_SMBUS_PROC_CALL:
> +               buf[0] = zx2967_i2c_readl(zx_i2c, REG_DATA);
> +               buf[1] = zx2967_i2c_readl(zx_i2c, REG_DATA);
> +               data->word = (buf[0] << 8) | buf[1];
> +               break;
> +       default:
> +               dev_warn(&adap->dev, "Unsupported transaction %d\n", size);
> +               return -EOPNOTSUPP;
> +       }
> +
> +       return 0;
> +}

I would revisit those several loooong functions for splitting/refactoring.

> +
> +static u32 zx2967_i2c_func(struct i2c_adapter *adap)
> +{
> +       return 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_PROC_CALL |
> +              I2C_FUNC_I2C | I2C_FUNC_SMBUS_I2C_BLOCK;
> +}

It's just
#define XXX YY1 | YY2 | ...

> +#ifdef CONFIG_PM
> +static int zx2967_i2c_suspend(struct device *dev)

Switch to __maybe_unuse.

> +static int zx2967_i2c_probe(struct platform_device *pdev)
> +{

> +       struct resource *res;
> +       struct zx2967_i2c_info *zx_i2c = NULL;

Redundant assignment.

> +       struct clk *clk;
> +       void __iomem *reg_base;

Reverse tree for all above until top of this function.

> +       int ret = 0;

Redundant assignment.

> +
> +       zx_i2c = devm_kzalloc(&pdev->dev, sizeof(*zx_i2c), GFP_KERNEL);
> +       if (!zx_i2c)
> +               return -ENOMEM;
> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

> +       if (!res) {
> +               dev_err(&pdev->dev, "missing io resource\n");
> +               return -EINVAL;
> +       }
> +

Completely redundant lines of code.

> +       reg_base = devm_ioremap_resource(&pdev->dev, res);
> +       if (IS_ERR(reg_base))
> +               return PTR_ERR(reg_base);
> +
> +       clk = devm_clk_get(&pdev->dev, NULL);
> +       if (IS_ERR(clk)) {
> +               dev_err(&pdev->dev, "missing controller clock");
> +               return PTR_ERR(clk);
> +       }
> +
> +       ret = clk_prepare_enable(clk);
> +       if (ret) {
> +               dev_err(&pdev->dev, "failed to enable i2c_clk\n");
> +               return ret;
> +       }
> +

> +       of_property_read_u32(pdev->dev.of_node,
> +                       "clock-frequency", &zx_i2c->clk_freq);

devce_property_read_uXX();

> +       zx_i2c->reg_base = reg_base;
> +       zx_i2c->clk = clk;

> +       zx_i2c->irq = platform_get_irq(pdev, 0);

Is this optional?
Otherwise has to be checked.

> +       zx_i2c->id = pdev->id;
> +       zx_i2c->dev = &pdev->dev;
> +
> +       zx_i2c->pin_scl = devm_pinctrl_get_select(&pdev->dev, "scl");
> +       if (IS_ERR(zx_i2c->pin_scl))
> +               dev_info(&pdev->dev, "scl pin is not specified in dts\n");
> +
> +       zx_i2c->pin_sda = devm_pinctrl_get_select(&pdev->dev, "sda");
> +       if (IS_ERR(zx_i2c->pin_sda))
> +               dev_info(&pdev->dev, "sda pin is not specified in dts\n");
> +
> +       spin_lock_init(&zx_i2c->lock);
> +       init_completion(&zx_i2c->complete);
> +       platform_set_drvdata(pdev, zx_i2c);
> +
> +       ret = zx2967_i2c_reset_hardware(zx_i2c);
> +       if (ret) {
> +               dev_err(&pdev->dev, "failed to initialize i2c controller\n");
> +               goto unprepare_clk;
> +       }
> +
> +       ret = devm_request_irq(&pdev->dev, zx_i2c->irq,
> +                       zx2967_i2c_isr, 0, dev_name(&pdev->dev), zx_i2c);
> +       if (ret) {
> +               dev_err(&pdev->dev, "failed to request irq %i\n", zx_i2c->irq);
> +               goto unprepare_clk;
> +       }
> +
> +       i2c_set_adapdata(&zx_i2c->adap, zx_i2c);

> +       zx_i2c->adap.owner = THIS_MODULE;

Do you need this?

> +       zx_i2c->adap.class = I2C_CLASS_DEPRECATED;
> +       strlcpy(zx_i2c->adap.name, "zx2967 i2c adapter",
> +               sizeof(zx_i2c->adap.name));
> +       zx_i2c->adap.algo = &zx2967_i2c_algo;
> +       zx_i2c->adap.dev.parent = &pdev->dev;
> +       zx_i2c->adap.nr = pdev->id;
> +       zx_i2c->adap.dev.of_node = pdev->dev.of_node;
> +
> +       ret = i2c_add_numbered_adapter(&zx_i2c->adap);
> +       if (ret) {
> +               dev_err(&pdev->dev, "failed to add zx2967 i2c adapter\n");
> +               goto unprepare_clk;
> +       }
> +
> +       return 0;
> +
> +unprepare_clk:

err_clk_unprepare:

> +       clk_unprepare(zx_i2c->clk);

Perhaps clk_disable_unprepare();

> +       return ret;
> +}
> +
> +static int zx2967_i2c_remove(struct platform_device *pdev)
> +{
> +       struct zx2967_i2c_info *zx_i2c = platform_get_drvdata(pdev);
> +
> +       i2c_del_adapter(&zx_i2c->adap);

> +       clk_unprepare(zx_i2c->clk);

Ditto.

> +
> +       return 0;
> +}

> +MODULE_AUTHOR("Baoyou Xie <baoyou.xie@linaro.org>");
> +MODULE_DESCRIPTION("ZTE zx2967 I2C Bus Controller driver");
> +MODULE_LICENSE("GPL v2");

When bool in Kconfig this all redundant.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v1 3/3] i2c: zx2967: add i2c controller driver for ZTE's zx2967 family

[Shawn Guo]

On Fri, Jan 20, 2017 at 04:43:47PM +0800, Baoyou Xie wrote:
> +static int zx2967_i2c_probe(struct platform_device *pdev)
> +{
> +	struct resource *res;
> +	struct zx2967_i2c_info *zx_i2c = NULL;
> +	struct clk *clk;
> +	void __iomem *reg_base;
> +	int ret = 0;
> +
> +	zx_i2c = devm_kzalloc(&pdev->dev, sizeof(*zx_i2c), GFP_KERNEL);
> +	if (!zx_i2c)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res) {
> +		dev_err(&pdev->dev, "missing io resource\n");
> +		return -EINVAL;
> +	}
> +
> +	reg_base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(reg_base))
> +		return PTR_ERR(reg_base);
> +
> +	clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(clk)) {
> +		dev_err(&pdev->dev, "missing controller clock");
> +		return PTR_ERR(clk);
> +	}
> +
> +	ret = clk_prepare_enable(clk);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to enable i2c_clk\n");
> +		return ret;
> +	}
> +
> +	of_property_read_u32(pdev->dev.of_node,
> +			"clock-frequency", &zx_i2c->clk_freq);
> +	zx_i2c->reg_base = reg_base;
> +	zx_i2c->clk = clk;
> +	zx_i2c->irq = platform_get_irq(pdev, 0);
> +	zx_i2c->id = pdev->id;
> +	zx_i2c->dev = &pdev->dev;
> +
> +	zx_i2c->pin_scl = devm_pinctrl_get_select(&pdev->dev, "scl");
> +	if (IS_ERR(zx_i2c->pin_scl))
> +		dev_info(&pdev->dev, "scl pin is not specified in dts\n");
> +
> +	zx_i2c->pin_sda = devm_pinctrl_get_select(&pdev->dev, "sda");
> +	if (IS_ERR(zx_i2c->pin_sda))
> +		dev_info(&pdev->dev, "sda pin is not specified in dts\n");

I don't understand why this is necessary.  For most cases, we only need
to specify needed pins in property 'pinctrl-0' and 'default' in
'pinctrl-names', and pinctrl/driver core will just set up the pins for
the device.

Shawn