[PATCH v7 1/3] dt: bindings: add documentation for zx2967 family i2c controller

[PATCH v7 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>
Acked-by: Rob Herring <robh@kernel.org>
---
 .../devicetree/bindings/i2c/i2c-zx2967.txt         | 24 ++++++++++++++++++++++
 1 file changed, 24 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..a528374
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-zx2967.txt
@@ -0,0 +1,24 @@
+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>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&i2c_global_pin>;
+	};
-- 
2.7.4

[PATCH v7 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>
Acked-by: Rob Herring <robh@kernel.org>
---
 .../devicetree/bindings/i2c/i2c-zx2967.txt         | 24 ++++++++++++++++++++++
 1 file changed, 24 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..a528374
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-zx2967.txt
@@ -0,0 +1,24 @@
+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 at 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>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&i2c_global_pin>;
+	};
-- 
2.7.4

[PATCH v7 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 e63063b..313fab5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1987,9 +1987,11 @@ 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/soc/zte/
 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/soc/zte/
 F:	include/dt-bindings/soc/zx*.h
 
-- 
2.7.4

[PATCH v7 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-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
---
 MAINTAINERS | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index e63063b..313fab5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1987,9 +1987,11 @@ L:	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.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/soc/zte/
 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/soc/zte/
 F:	include/dt-bindings/soc/zx*.h
 
-- 
2.7.4

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[PATCH v7 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 e63063b..313fab5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1987,9 +1987,11 @@ L:	linux-arm-kernel at 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/soc/zte/
 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/soc/zte/
 F:	include/dt-bindings/soc/zx*.h
 
-- 
2.7.4

[PATCH v7 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>
Reviewed-by: Shawn Guo <shawnguo@kernel.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
---
 drivers/i2c/busses/Kconfig      |   9 +
 drivers/i2c/busses/Makefile     |   1 +
 drivers/i2c/busses/i2c-zx2967.c | 667 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 677 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-zx2967.c

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index e4a603e..d983e36 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -1246,4 +1246,13 @@ 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
+	tristate "ZTE zx2967 I2C support"
+	depends on ARCH_ZX
+	default y
+	help
+	  Selecting this option will add ZX2967 I2C driver.
+	  This driver can also be built as a module. If so, the module will be
+	  called i2c-zx2967.
+
 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..f136aee
--- /dev/null
+++ b/drivers/i2c/busses/i2c-zx2967.c
@@ -0,0 +1,667 @@
+/*
+ * 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/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#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			BIT(0)
+#define I2C_ADDR_MODE_TEN		BIT(1)
+#define I2C_IRQ_MSK_ENABLE		BIT(3)
+#define I2C_RW_READ			BIT(4)
+#define I2C_CMB_RW_EN			BIT(5)
+#define I2C_START			BIT(6)
+
+#define I2C_ADDR_LOW_MASK		GENMASK(6, 0)
+#define I2C_ADDR_LOW_SHIFT		0
+#define I2C_ADDR_HI_MASK		GENMASK(2, 0)
+#define I2C_ADDR_HI_SHIFT		7
+
+#define I2C_WFIFO_RESET			BIT(7)
+#define I2C_RFIFO_RESET			BIT(7)
+
+#define I2C_IRQ_ACK_CLEAR		BIT(7)
+#define I2C_INT_MASK			GENMASK(6, 0)
+
+#define I2C_TRANS_DONE			BIT(0)
+#define I2C_ERROR_DEVICE		BIT(1)
+#define I2C_ERROR_DATA			BIT(2)
+#define I2C_ERROR_MASK			GENMASK(2, 1)
+
+#define I2C_SR_BUSY			BIT(6)
+
+#define I2C_SR_EDEVICE			BIT(1)
+#define I2C_SR_EDATA			BIT(2)
+
+#define I2C_FIFO_MAX			16
+
+#define I2C_TIMEOUT			msecs_to_jiffies(1000)
+
+#define DEV(i2c)			(&i2c->adap.dev)
+
+struct zx2967_i2c_info {
+	struct i2c_adapter	adap;
+	struct clk		*clk;
+	struct completion	complete;
+	u32			clk_freq;
+	void __iomem		*reg_base;
+	size_t			residue;
+	int			irq;
+	int			msg_rd;
+	u8			*cur_trans;
+	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 void zx2967_i2c_flush_fifos(struct zx2967_i2c_info *zx_i2c)
+{
+	u32 offset;
+	u32 val;
+
+	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);
+}
+
+static int zx2967_i2c_empty_rx_fifo(struct zx2967_i2c_info *zx_i2c, u32 size)
+{
+	u8 val[I2C_FIFO_MAX] = {0};
+	int i;
+
+	if (size > I2C_FIFO_MAX) {
+		dev_err(DEV(zx_i2c), "fifo size %d over the max value %d\n",
+			size, I2C_FIFO_MAX);
+		return -EINVAL;
+	}
+
+	zx2967_i2c_readsb(zx_i2c, val, REG_DATA, size);
+	for (i = 0; i < size; i++) {
+		*zx_i2c->cur_trans++ = val[i];
+		zx_i2c->residue--;
+	}
+
+	barrier();
+
+	return 0;
+}
+
+static int zx2967_i2c_fill_tx_fifo(struct zx2967_i2c_info *zx_i2c)
+{
+	size_t residue = zx_i2c->residue;
+	u8 *buf = zx_i2c->cur_trans;
+
+	if (residue == 0) {
+		dev_err(DEV(zx_i2c), "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->cur_trans = NULL;
+	} else {
+		zx2967_i2c_writesb(zx_i2c, buf, REG_DATA, I2C_FIFO_MAX);
+		zx_i2c->residue -= I2C_FIFO_MAX;
+		zx_i2c->cur_trans += 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);
+
+	zx2967_i2c_flush_fifos(zx_i2c);
+
+	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;
+
+	status = zx2967_i2c_readl(zx_i2c, REG_STAT) & I2C_INT_MASK;
+	zx2967_i2c_isr_clr(zx_i2c);
+
+	if (status & I2C_ERROR_MASK)
+		return IRQ_HANDLED;
+
+	if (status & I2C_TRANS_DONE)
+		complete(&zx_i2c->complete);
+
+	return IRQ_HANDLED;
+}
+
+static void zx2967_set_addr(struct zx2967_i2c_info *zx_i2c, u16 addr)
+{
+	u16 val;
+
+	val = (addr >> I2C_ADDR_LOW_SHIFT) & I2C_ADDR_LOW_MASK;
+	zx2967_i2c_writel(zx_i2c, val, REG_DEVADDR_L);
+
+	val = (addr >> I2C_ADDR_HI_SHIFT) & I2C_ADDR_HI_MASK;
+	zx2967_i2c_writel(zx_i2c, val, REG_DEVADDR_H);
+	if (val)
+		val = zx2967_i2c_readl(zx_i2c, REG_CMD) | I2C_ADDR_MODE_TEN;
+	else
+		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_read_bytes(struct zx2967_i2c_info *zx_i2c, u32 bytes)
+{
+	unsigned long time_left;
+
+	reinit_completion(&zx_i2c->complete);
+	zx2967_i2c_writel(zx_i2c, bytes - 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(DEV(zx_i2c), "read i2c transfer timed out\n");
+		disable_irq(zx_i2c->irq);
+		zx2967_i2c_reset_hardware(zx_i2c);
+		return -EIO;
+	}
+
+	return zx2967_i2c_empty_rx_fifo(zx_i2c, bytes);
+}
+
+static int zx2967_i2c_xfer_read(struct zx2967_i2c_info *zx_i2c)
+{
+	int ret;
+	int i;
+
+	for (i = 0; i < zx_i2c->access_cnt; i++) {
+		ret = zx2967_i2c_xfer_read_bytes(zx_i2c, I2C_FIFO_MAX);
+		if (ret)
+			return ret;
+	}
+
+	if (zx_i2c->residue > 0) {
+		ret = zx2967_i2c_xfer_read_bytes(zx_i2c, zx_i2c->residue);
+		if (ret)
+			return ret;
+	}
+
+	zx_i2c->residue = 0;
+	zx_i2c->access_cnt = 0;
+	return 0;
+}
+
+static int
+zx2967_i2c_xfer_write_bytes(struct zx2967_i2c_info *zx_i2c, u32 bytes)
+{
+	unsigned long time_left;
+	int ret;
+
+	reinit_completion(&zx_i2c->complete);
+
+	ret = zx2967_i2c_fill_tx_fifo(zx_i2c);
+	if (ret)
+		return ret;
+
+	zx2967_i2c_start_ctrl(zx_i2c);
+
+	time_left = wait_for_completion_timeout(&zx_i2c->complete,
+				I2C_TIMEOUT);
+	if (time_left == 0) {
+		dev_err(DEV(zx_i2c), "write i2c transfer timed out\n");
+		disable_irq(zx_i2c->irq);
+		zx2967_i2c_reset_hardware(zx_i2c);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int zx2967_i2c_xfer_write(struct zx2967_i2c_info *zx_i2c)
+{
+	int ret;
+	int i;
+
+	for (i = 0; i < zx_i2c->access_cnt; i++) {
+		ret = zx2967_i2c_xfer_write_bytes(zx_i2c, I2C_FIFO_MAX);
+		if (ret)
+			return ret;
+	}
+
+	if (zx_i2c->residue > 0) {
+		ret = zx2967_i2c_xfer_write_bytes(zx_i2c, zx_i2c->residue);
+		if (ret)
+			return ret;
+	}
+
+	zx_i2c->residue = 0;
+	zx_i2c->access_cnt = 0;
+	return 0;
+}
+
+static int zx2967_i2c_xfer_msg(struct zx2967_i2c_info *zx_i2c,
+			       struct i2c_msg *msg)
+{
+	if (msg->len == 0)
+		return -EINVAL;
+
+	zx2967_i2c_flush_fifos(zx_i2c);
+
+	zx_i2c->cur_trans = 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)
+		return zx2967_i2c_xfer_read(zx_i2c);
+
+	return zx2967_i2c_xfer_write(zx_i2c);
+}
+
+static int zx2967_i2c_xfer(struct i2c_adapter *adap,
+			   struct i2c_msg *msgs, int num)
+{
+	struct zx2967_i2c_info *zx_i2c = i2c_get_adapdata(adap);
+	int ret;
+	int i;
+
+	if (zx_i2c->is_suspended)
+		return -EBUSY;
+
+	zx2967_set_addr(zx_i2c, msgs->addr);
+
+	for (i = 0; i < num; i++) {
+		ret = zx2967_i2c_xfer_msg(zx_i2c, &msgs[i]);
+		if (ret)
+			return ret;
+	}
+
+	return num;
+}
+
+static void
+zx2967_smbus_xfer_prepare(struct zx2967_i2c_info *zx_i2c, u16 addr,
+			  char read_write, u8 command, int size,
+			  union i2c_smbus_data *data)
+{
+	u32 val;
+
+	val = zx2967_i2c_readl(zx_i2c, REG_RDCONF);
+	val |= I2C_RFIFO_RESET;
+	zx2967_i2c_writel(zx_i2c, val, REG_RDCONF);
+	zx2967_set_addr(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_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);
+		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;
+	}
+}
+
+static int zx2967_smbus_xfer_read(struct zx2967_i2c_info *zx_i2c, int size,
+				  union i2c_smbus_data *data)
+{
+	unsigned long time_left;
+	u8 buf[2];
+	u32 val;
+
+	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(DEV(zx_i2c), "i2c read transfer timed out\n");
+		disable_irq(zx_i2c->irq);
+		zx2967_i2c_reset_hardware(zx_i2c);
+		return -EIO;
+	}
+
+	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(DEV(zx_i2c), "Unsupported transaction %d\n", size);
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int zx2967_smbus_xfer_write(struct zx2967_i2c_info *zx_i2c)
+{
+	unsigned long time_left;
+	u32 val;
+
+	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(DEV(zx_i2c), "i2c write transfer timed out\n");
+		disable_irq(zx_i2c->irq);
+		zx2967_i2c_reset_hardware(zx_i2c);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+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);
+
+	if (size == I2C_SMBUS_QUICK)
+		read_write = I2C_SMBUS_WRITE;
+
+	switch (size) {
+	case I2C_SMBUS_QUICK:
+	case I2C_SMBUS_BYTE:
+	case I2C_SMBUS_BYTE_DATA:
+	case I2C_SMBUS_WORD_DATA:
+		zx2967_smbus_xfer_prepare(zx_i2c, addr, read_write,
+					  command, size, data);
+		break;
+	default:
+		dev_warn(&adap->dev, "Unsupported transaction %d\n", size);
+		return -EOPNOTSUPP;
+	}
+
+	if (read_write == I2C_SMBUS_READ)
+		return zx2967_smbus_xfer_read(zx_i2c, size, data);
+
+	return zx2967_smbus_xfer_write(zx_i2c);
+}
+
+#define ZX2967_I2C_FUNCS (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)
+
+static u32 zx2967_i2c_func(struct i2c_adapter *adap)
+{
+	return ZX2967_I2C_FUNCS;
+}
+
+static int __maybe_unused zx2967_i2c_suspend(struct device *dev)
+{
+	struct zx2967_i2c_info *zx_i2c = dev_get_drvdata(dev);
+
+	zx_i2c->is_suspended = true;
+	clk_disable_unprepare(zx_i2c->clk);
+
+	return 0;
+}
+
+static int __maybe_unused 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 SIMPLE_DEV_PM_OPS(zx2967_i2c_dev_pm_ops,
+			 zx2967_i2c_suspend, zx2967_i2c_resume);
+
+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 zx2967_i2c_info *zx_i2c;
+	void __iomem *reg_base;
+	struct resource *res;
+	struct clk *clk;
+	int ret;
+
+	zx_i2c = devm_kzalloc(&pdev->dev, sizeof(*zx_i2c), GFP_KERNEL);
+	if (!zx_i2c)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	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;
+	}
+
+	ret = device_property_read_u32(&pdev->dev, "clock-frequency",
+				       &zx_i2c->clk_freq);
+	if (ret) {
+		dev_err(&pdev->dev, "missing clock-frequency");
+		return ret;
+	}
+
+	ret = platform_get_irq(pdev, 0);
+	if (ret < 0)
+		return ret;
+
+	zx_i2c->irq = ret;
+	zx_i2c->reg_base = reg_base;
+	zx_i2c->clk = clk;
+
+	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 err_clk_unprepare;
+	}
+
+	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 err_clk_unprepare;
+	}
+
+	i2c_set_adapdata(&zx_i2c->adap, zx_i2c);
+	strlcpy(zx_i2c->adap.name, "zx2967 i2c adapter",
+		sizeof(zx_i2c->adap.name));
+	zx_i2c->adap.algo = &zx2967_i2c_algo;
+	zx_i2c->adap.nr = pdev->id;
+	zx_i2c->adap.dev.parent = &pdev->dev;
+	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 err_clk_unprepare;
+	}
+
+	return 0;
+err_clk_unprepare:
+	clk_disable_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_disable_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

[PATCH v7 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-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Reviewed-by: Shawn Guo <shawnguo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 drivers/i2c/busses/Kconfig      |   9 +
 drivers/i2c/busses/Makefile     |   1 +
 drivers/i2c/busses/i2c-zx2967.c | 667 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 677 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-zx2967.c

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index e4a603e..d983e36 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -1246,4 +1246,13 @@ 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
+	tristate "ZTE zx2967 I2C support"
+	depends on ARCH_ZX
+	default y
+	help
+	  Selecting this option will add ZX2967 I2C driver.
+	  This driver can also be built as a module. If so, the module will be
+	  called i2c-zx2967.
+
 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..f136aee
--- /dev/null
+++ b/drivers/i2c/busses/i2c-zx2967.c
@@ -0,0 +1,667 @@
+/*
+ * ZTE's zx2967 family i2c bus controller driver
+ *
+ * Copyright (C) 2017 ZTE Ltd.
+ *
+ * Author: Baoyou Xie <baoyou.xie-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ */
+
+#include <linux/clk.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#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			BIT(0)
+#define I2C_ADDR_MODE_TEN		BIT(1)
+#define I2C_IRQ_MSK_ENABLE		BIT(3)
+#define I2C_RW_READ			BIT(4)
+#define I2C_CMB_RW_EN			BIT(5)
+#define I2C_START			BIT(6)
+
+#define I2C_ADDR_LOW_MASK		GENMASK(6, 0)
+#define I2C_ADDR_LOW_SHIFT		0
+#define I2C_ADDR_HI_MASK		GENMASK(2, 0)
+#define I2C_ADDR_HI_SHIFT		7
+
+#define I2C_WFIFO_RESET			BIT(7)
+#define I2C_RFIFO_RESET			BIT(7)
+
+#define I2C_IRQ_ACK_CLEAR		BIT(7)
+#define I2C_INT_MASK			GENMASK(6, 0)
+
+#define I2C_TRANS_DONE			BIT(0)
+#define I2C_ERROR_DEVICE		BIT(1)
+#define I2C_ERROR_DATA			BIT(2)
+#define I2C_ERROR_MASK			GENMASK(2, 1)
+
+#define I2C_SR_BUSY			BIT(6)
+
+#define I2C_SR_EDEVICE			BIT(1)
+#define I2C_SR_EDATA			BIT(2)
+
+#define I2C_FIFO_MAX			16
+
+#define I2C_TIMEOUT			msecs_to_jiffies(1000)
+
+#define DEV(i2c)			(&i2c->adap.dev)
+
+struct zx2967_i2c_info {
+	struct i2c_adapter	adap;
+	struct clk		*clk;
+	struct completion	complete;
+	u32			clk_freq;
+	void __iomem		*reg_base;
+	size_t			residue;
+	int			irq;
+	int			msg_rd;
+	u8			*cur_trans;
+	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 void zx2967_i2c_flush_fifos(struct zx2967_i2c_info *zx_i2c)
+{
+	u32 offset;
+	u32 val;
+
+	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);
+}
+
+static int zx2967_i2c_empty_rx_fifo(struct zx2967_i2c_info *zx_i2c, u32 size)
+{
+	u8 val[I2C_FIFO_MAX] = {0};
+	int i;
+
+	if (size > I2C_FIFO_MAX) {
+		dev_err(DEV(zx_i2c), "fifo size %d over the max value %d\n",
+			size, I2C_FIFO_MAX);
+		return -EINVAL;
+	}
+
+	zx2967_i2c_readsb(zx_i2c, val, REG_DATA, size);
+	for (i = 0; i < size; i++) {
+		*zx_i2c->cur_trans++ = val[i];
+		zx_i2c->residue--;
+	}
+
+	barrier();
+
+	return 0;
+}
+
+static int zx2967_i2c_fill_tx_fifo(struct zx2967_i2c_info *zx_i2c)
+{
+	size_t residue = zx_i2c->residue;
+	u8 *buf = zx_i2c->cur_trans;
+
+	if (residue == 0) {
+		dev_err(DEV(zx_i2c), "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->cur_trans = NULL;
+	} else {
+		zx2967_i2c_writesb(zx_i2c, buf, REG_DATA, I2C_FIFO_MAX);
+		zx_i2c->residue -= I2C_FIFO_MAX;
+		zx_i2c->cur_trans += 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);
+
+	zx2967_i2c_flush_fifos(zx_i2c);
+
+	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;
+
+	status = zx2967_i2c_readl(zx_i2c, REG_STAT) & I2C_INT_MASK;
+	zx2967_i2c_isr_clr(zx_i2c);
+
+	if (status & I2C_ERROR_MASK)
+		return IRQ_HANDLED;
+
+	if (status & I2C_TRANS_DONE)
+		complete(&zx_i2c->complete);
+
+	return IRQ_HANDLED;
+}
+
+static void zx2967_set_addr(struct zx2967_i2c_info *zx_i2c, u16 addr)
+{
+	u16 val;
+
+	val = (addr >> I2C_ADDR_LOW_SHIFT) & I2C_ADDR_LOW_MASK;
+	zx2967_i2c_writel(zx_i2c, val, REG_DEVADDR_L);
+
+	val = (addr >> I2C_ADDR_HI_SHIFT) & I2C_ADDR_HI_MASK;
+	zx2967_i2c_writel(zx_i2c, val, REG_DEVADDR_H);
+	if (val)
+		val = zx2967_i2c_readl(zx_i2c, REG_CMD) | I2C_ADDR_MODE_TEN;
+	else
+		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_read_bytes(struct zx2967_i2c_info *zx_i2c, u32 bytes)
+{
+	unsigned long time_left;
+
+	reinit_completion(&zx_i2c->complete);
+	zx2967_i2c_writel(zx_i2c, bytes - 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(DEV(zx_i2c), "read i2c transfer timed out\n");
+		disable_irq(zx_i2c->irq);
+		zx2967_i2c_reset_hardware(zx_i2c);
+		return -EIO;
+	}
+
+	return zx2967_i2c_empty_rx_fifo(zx_i2c, bytes);
+}
+
+static int zx2967_i2c_xfer_read(struct zx2967_i2c_info *zx_i2c)
+{
+	int ret;
+	int i;
+
+	for (i = 0; i < zx_i2c->access_cnt; i++) {
+		ret = zx2967_i2c_xfer_read_bytes(zx_i2c, I2C_FIFO_MAX);
+		if (ret)
+			return ret;
+	}
+
+	if (zx_i2c->residue > 0) {
+		ret = zx2967_i2c_xfer_read_bytes(zx_i2c, zx_i2c->residue);
+		if (ret)
+			return ret;
+	}
+
+	zx_i2c->residue = 0;
+	zx_i2c->access_cnt = 0;
+	return 0;
+}
+
+static int
+zx2967_i2c_xfer_write_bytes(struct zx2967_i2c_info *zx_i2c, u32 bytes)
+{
+	unsigned long time_left;
+	int ret;
+
+	reinit_completion(&zx_i2c->complete);
+
+	ret = zx2967_i2c_fill_tx_fifo(zx_i2c);
+	if (ret)
+		return ret;
+
+	zx2967_i2c_start_ctrl(zx_i2c);
+
+	time_left = wait_for_completion_timeout(&zx_i2c->complete,
+				I2C_TIMEOUT);
+	if (time_left == 0) {
+		dev_err(DEV(zx_i2c), "write i2c transfer timed out\n");
+		disable_irq(zx_i2c->irq);
+		zx2967_i2c_reset_hardware(zx_i2c);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int zx2967_i2c_xfer_write(struct zx2967_i2c_info *zx_i2c)
+{
+	int ret;
+	int i;
+
+	for (i = 0; i < zx_i2c->access_cnt; i++) {
+		ret = zx2967_i2c_xfer_write_bytes(zx_i2c, I2C_FIFO_MAX);
+		if (ret)
+			return ret;
+	}
+
+	if (zx_i2c->residue > 0) {
+		ret = zx2967_i2c_xfer_write_bytes(zx_i2c, zx_i2c->residue);
+		if (ret)
+			return ret;
+	}
+
+	zx_i2c->residue = 0;
+	zx_i2c->access_cnt = 0;
+	return 0;
+}
+
+static int zx2967_i2c_xfer_msg(struct zx2967_i2c_info *zx_i2c,
+			       struct i2c_msg *msg)
+{
+	if (msg->len == 0)
+		return -EINVAL;
+
+	zx2967_i2c_flush_fifos(zx_i2c);
+
+	zx_i2c->cur_trans = 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)
+		return zx2967_i2c_xfer_read(zx_i2c);
+
+	return zx2967_i2c_xfer_write(zx_i2c);
+}
+
+static int zx2967_i2c_xfer(struct i2c_adapter *adap,
+			   struct i2c_msg *msgs, int num)
+{
+	struct zx2967_i2c_info *zx_i2c = i2c_get_adapdata(adap);
+	int ret;
+	int i;
+
+	if (zx_i2c->is_suspended)
+		return -EBUSY;
+
+	zx2967_set_addr(zx_i2c, msgs->addr);
+
+	for (i = 0; i < num; i++) {
+		ret = zx2967_i2c_xfer_msg(zx_i2c, &msgs[i]);
+		if (ret)
+			return ret;
+	}
+
+	return num;
+}
+
+static void
+zx2967_smbus_xfer_prepare(struct zx2967_i2c_info *zx_i2c, u16 addr,
+			  char read_write, u8 command, int size,
+			  union i2c_smbus_data *data)
+{
+	u32 val;
+
+	val = zx2967_i2c_readl(zx_i2c, REG_RDCONF);
+	val |= I2C_RFIFO_RESET;
+	zx2967_i2c_writel(zx_i2c, val, REG_RDCONF);
+	zx2967_set_addr(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_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);
+		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;
+	}
+}
+
+static int zx2967_smbus_xfer_read(struct zx2967_i2c_info *zx_i2c, int size,
+				  union i2c_smbus_data *data)
+{
+	unsigned long time_left;
+	u8 buf[2];
+	u32 val;
+
+	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(DEV(zx_i2c), "i2c read transfer timed out\n");
+		disable_irq(zx_i2c->irq);
+		zx2967_i2c_reset_hardware(zx_i2c);
+		return -EIO;
+	}
+
+	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(DEV(zx_i2c), "Unsupported transaction %d\n", size);
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int zx2967_smbus_xfer_write(struct zx2967_i2c_info *zx_i2c)
+{
+	unsigned long time_left;
+	u32 val;
+
+	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(DEV(zx_i2c), "i2c write transfer timed out\n");
+		disable_irq(zx_i2c->irq);
+		zx2967_i2c_reset_hardware(zx_i2c);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+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);
+
+	if (size == I2C_SMBUS_QUICK)
+		read_write = I2C_SMBUS_WRITE;
+
+	switch (size) {
+	case I2C_SMBUS_QUICK:
+	case I2C_SMBUS_BYTE:
+	case I2C_SMBUS_BYTE_DATA:
+	case I2C_SMBUS_WORD_DATA:
+		zx2967_smbus_xfer_prepare(zx_i2c, addr, read_write,
+					  command, size, data);
+		break;
+	default:
+		dev_warn(&adap->dev, "Unsupported transaction %d\n", size);
+		return -EOPNOTSUPP;
+	}
+
+	if (read_write == I2C_SMBUS_READ)
+		return zx2967_smbus_xfer_read(zx_i2c, size, data);
+
+	return zx2967_smbus_xfer_write(zx_i2c);
+}
+
+#define ZX2967_I2C_FUNCS (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)
+
+static u32 zx2967_i2c_func(struct i2c_adapter *adap)
+{
+	return ZX2967_I2C_FUNCS;
+}
+
+static int __maybe_unused zx2967_i2c_suspend(struct device *dev)
+{
+	struct zx2967_i2c_info *zx_i2c = dev_get_drvdata(dev);
+
+	zx_i2c->is_suspended = true;
+	clk_disable_unprepare(zx_i2c->clk);
+
+	return 0;
+}
+
+static int __maybe_unused 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 SIMPLE_DEV_PM_OPS(zx2967_i2c_dev_pm_ops,
+			 zx2967_i2c_suspend, zx2967_i2c_resume);
+
+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 zx2967_i2c_info *zx_i2c;
+	void __iomem *reg_base;
+	struct resource *res;
+	struct clk *clk;
+	int ret;
+
+	zx_i2c = devm_kzalloc(&pdev->dev, sizeof(*zx_i2c), GFP_KERNEL);
+	if (!zx_i2c)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	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;
+	}
+
+	ret = device_property_read_u32(&pdev->dev, "clock-frequency",
+				       &zx_i2c->clk_freq);
+	if (ret) {
+		dev_err(&pdev->dev, "missing clock-frequency");
+		return ret;
+	}
+
+	ret = platform_get_irq(pdev, 0);
+	if (ret < 0)
+		return ret;
+
+	zx_i2c->irq = ret;
+	zx_i2c->reg_base = reg_base;
+	zx_i2c->clk = clk;
+
+	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 err_clk_unprepare;
+	}
+
+	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 err_clk_unprepare;
+	}
+
+	i2c_set_adapdata(&zx_i2c->adap, zx_i2c);
+	strlcpy(zx_i2c->adap.name, "zx2967 i2c adapter",
+		sizeof(zx_i2c->adap.name));
+	zx_i2c->adap.algo = &zx2967_i2c_algo;
+	zx_i2c->adap.nr = pdev->id;
+	zx_i2c->adap.dev.parent = &pdev->dev;
+	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 err_clk_unprepare;
+	}
+
+	return 0;
+err_clk_unprepare:
+	clk_disable_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_disable_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-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>");
+MODULE_DESCRIPTION("ZTE zx2967 I2C Bus Controller driver");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4

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[PATCH v7 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>
Reviewed-by: Shawn Guo <shawnguo@kernel.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
---
 drivers/i2c/busses/Kconfig      |   9 +
 drivers/i2c/busses/Makefile     |   1 +
 drivers/i2c/busses/i2c-zx2967.c | 667 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 677 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-zx2967.c

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index e4a603e..d983e36 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -1246,4 +1246,13 @@ 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
+	tristate "ZTE zx2967 I2C support"
+	depends on ARCH_ZX
+	default y
+	help
+	  Selecting this option will add ZX2967 I2C driver.
+	  This driver can also be built as a module. If so, the module will be
+	  called i2c-zx2967.
+
 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..f136aee
--- /dev/null
+++ b/drivers/i2c/busses/i2c-zx2967.c
@@ -0,0 +1,667 @@
+/*
+ * 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/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#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			BIT(0)
+#define I2C_ADDR_MODE_TEN		BIT(1)
+#define I2C_IRQ_MSK_ENABLE		BIT(3)
+#define I2C_RW_READ			BIT(4)
+#define I2C_CMB_RW_EN			BIT(5)
+#define I2C_START			BIT(6)
+
+#define I2C_ADDR_LOW_MASK		GENMASK(6, 0)
+#define I2C_ADDR_LOW_SHIFT		0
+#define I2C_ADDR_HI_MASK		GENMASK(2, 0)
+#define I2C_ADDR_HI_SHIFT		7
+
+#define I2C_WFIFO_RESET			BIT(7)
+#define I2C_RFIFO_RESET			BIT(7)
+
+#define I2C_IRQ_ACK_CLEAR		BIT(7)
+#define I2C_INT_MASK			GENMASK(6, 0)
+
+#define I2C_TRANS_DONE			BIT(0)
+#define I2C_ERROR_DEVICE		BIT(1)
+#define I2C_ERROR_DATA			BIT(2)
+#define I2C_ERROR_MASK			GENMASK(2, 1)
+
+#define I2C_SR_BUSY			BIT(6)
+
+#define I2C_SR_EDEVICE			BIT(1)
+#define I2C_SR_EDATA			BIT(2)
+
+#define I2C_FIFO_MAX			16
+
+#define I2C_TIMEOUT			msecs_to_jiffies(1000)
+
+#define DEV(i2c)			(&i2c->adap.dev)
+
+struct zx2967_i2c_info {
+	struct i2c_adapter	adap;
+	struct clk		*clk;
+	struct completion	complete;
+	u32			clk_freq;
+	void __iomem		*reg_base;
+	size_t			residue;
+	int			irq;
+	int			msg_rd;
+	u8			*cur_trans;
+	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 void zx2967_i2c_flush_fifos(struct zx2967_i2c_info *zx_i2c)
+{
+	u32 offset;
+	u32 val;
+
+	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);
+}
+
+static int zx2967_i2c_empty_rx_fifo(struct zx2967_i2c_info *zx_i2c, u32 size)
+{
+	u8 val[I2C_FIFO_MAX] = {0};
+	int i;
+
+	if (size > I2C_FIFO_MAX) {
+		dev_err(DEV(zx_i2c), "fifo size %d over the max value %d\n",
+			size, I2C_FIFO_MAX);
+		return -EINVAL;
+	}
+
+	zx2967_i2c_readsb(zx_i2c, val, REG_DATA, size);
+	for (i = 0; i < size; i++) {
+		*zx_i2c->cur_trans++ = val[i];
+		zx_i2c->residue--;
+	}
+
+	barrier();
+
+	return 0;
+}
+
+static int zx2967_i2c_fill_tx_fifo(struct zx2967_i2c_info *zx_i2c)
+{
+	size_t residue = zx_i2c->residue;
+	u8 *buf = zx_i2c->cur_trans;
+
+	if (residue == 0) {
+		dev_err(DEV(zx_i2c), "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->cur_trans = NULL;
+	} else {
+		zx2967_i2c_writesb(zx_i2c, buf, REG_DATA, I2C_FIFO_MAX);
+		zx_i2c->residue -= I2C_FIFO_MAX;
+		zx_i2c->cur_trans += 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);
+
+	zx2967_i2c_flush_fifos(zx_i2c);
+
+	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;
+
+	status = zx2967_i2c_readl(zx_i2c, REG_STAT) & I2C_INT_MASK;
+	zx2967_i2c_isr_clr(zx_i2c);
+
+	if (status & I2C_ERROR_MASK)
+		return IRQ_HANDLED;
+
+	if (status & I2C_TRANS_DONE)
+		complete(&zx_i2c->complete);
+
+	return IRQ_HANDLED;
+}
+
+static void zx2967_set_addr(struct zx2967_i2c_info *zx_i2c, u16 addr)
+{
+	u16 val;
+
+	val = (addr >> I2C_ADDR_LOW_SHIFT) & I2C_ADDR_LOW_MASK;
+	zx2967_i2c_writel(zx_i2c, val, REG_DEVADDR_L);
+
+	val = (addr >> I2C_ADDR_HI_SHIFT) & I2C_ADDR_HI_MASK;
+	zx2967_i2c_writel(zx_i2c, val, REG_DEVADDR_H);
+	if (val)
+		val = zx2967_i2c_readl(zx_i2c, REG_CMD) | I2C_ADDR_MODE_TEN;
+	else
+		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_read_bytes(struct zx2967_i2c_info *zx_i2c, u32 bytes)
+{
+	unsigned long time_left;
+
+	reinit_completion(&zx_i2c->complete);
+	zx2967_i2c_writel(zx_i2c, bytes - 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(DEV(zx_i2c), "read i2c transfer timed out\n");
+		disable_irq(zx_i2c->irq);
+		zx2967_i2c_reset_hardware(zx_i2c);
+		return -EIO;
+	}
+
+	return zx2967_i2c_empty_rx_fifo(zx_i2c, bytes);
+}
+
+static int zx2967_i2c_xfer_read(struct zx2967_i2c_info *zx_i2c)
+{
+	int ret;
+	int i;
+
+	for (i = 0; i < zx_i2c->access_cnt; i++) {
+		ret = zx2967_i2c_xfer_read_bytes(zx_i2c, I2C_FIFO_MAX);
+		if (ret)
+			return ret;
+	}
+
+	if (zx_i2c->residue > 0) {
+		ret = zx2967_i2c_xfer_read_bytes(zx_i2c, zx_i2c->residue);
+		if (ret)
+			return ret;
+	}
+
+	zx_i2c->residue = 0;
+	zx_i2c->access_cnt = 0;
+	return 0;
+}
+
+static int
+zx2967_i2c_xfer_write_bytes(struct zx2967_i2c_info *zx_i2c, u32 bytes)
+{
+	unsigned long time_left;
+	int ret;
+
+	reinit_completion(&zx_i2c->complete);
+
+	ret = zx2967_i2c_fill_tx_fifo(zx_i2c);
+	if (ret)
+		return ret;
+
+	zx2967_i2c_start_ctrl(zx_i2c);
+
+	time_left = wait_for_completion_timeout(&zx_i2c->complete,
+				I2C_TIMEOUT);
+	if (time_left == 0) {
+		dev_err(DEV(zx_i2c), "write i2c transfer timed out\n");
+		disable_irq(zx_i2c->irq);
+		zx2967_i2c_reset_hardware(zx_i2c);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int zx2967_i2c_xfer_write(struct zx2967_i2c_info *zx_i2c)
+{
+	int ret;
+	int i;
+
+	for (i = 0; i < zx_i2c->access_cnt; i++) {
+		ret = zx2967_i2c_xfer_write_bytes(zx_i2c, I2C_FIFO_MAX);
+		if (ret)
+			return ret;
+	}
+
+	if (zx_i2c->residue > 0) {
+		ret = zx2967_i2c_xfer_write_bytes(zx_i2c, zx_i2c->residue);
+		if (ret)
+			return ret;
+	}
+
+	zx_i2c->residue = 0;
+	zx_i2c->access_cnt = 0;
+	return 0;
+}
+
+static int zx2967_i2c_xfer_msg(struct zx2967_i2c_info *zx_i2c,
+			       struct i2c_msg *msg)
+{
+	if (msg->len == 0)
+		return -EINVAL;
+
+	zx2967_i2c_flush_fifos(zx_i2c);
+
+	zx_i2c->cur_trans = 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)
+		return zx2967_i2c_xfer_read(zx_i2c);
+
+	return zx2967_i2c_xfer_write(zx_i2c);
+}
+
+static int zx2967_i2c_xfer(struct i2c_adapter *adap,
+			   struct i2c_msg *msgs, int num)
+{
+	struct zx2967_i2c_info *zx_i2c = i2c_get_adapdata(adap);
+	int ret;
+	int i;
+
+	if (zx_i2c->is_suspended)
+		return -EBUSY;
+
+	zx2967_set_addr(zx_i2c, msgs->addr);
+
+	for (i = 0; i < num; i++) {
+		ret = zx2967_i2c_xfer_msg(zx_i2c, &msgs[i]);
+		if (ret)
+			return ret;
+	}
+
+	return num;
+}
+
+static void
+zx2967_smbus_xfer_prepare(struct zx2967_i2c_info *zx_i2c, u16 addr,
+			  char read_write, u8 command, int size,
+			  union i2c_smbus_data *data)
+{
+	u32 val;
+
+	val = zx2967_i2c_readl(zx_i2c, REG_RDCONF);
+	val |= I2C_RFIFO_RESET;
+	zx2967_i2c_writel(zx_i2c, val, REG_RDCONF);
+	zx2967_set_addr(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_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);
+		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;
+	}
+}
+
+static int zx2967_smbus_xfer_read(struct zx2967_i2c_info *zx_i2c, int size,
+				  union i2c_smbus_data *data)
+{
+	unsigned long time_left;
+	u8 buf[2];
+	u32 val;
+
+	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(DEV(zx_i2c), "i2c read transfer timed out\n");
+		disable_irq(zx_i2c->irq);
+		zx2967_i2c_reset_hardware(zx_i2c);
+		return -EIO;
+	}
+
+	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(DEV(zx_i2c), "Unsupported transaction %d\n", size);
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int zx2967_smbus_xfer_write(struct zx2967_i2c_info *zx_i2c)
+{
+	unsigned long time_left;
+	u32 val;
+
+	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(DEV(zx_i2c), "i2c write transfer timed out\n");
+		disable_irq(zx_i2c->irq);
+		zx2967_i2c_reset_hardware(zx_i2c);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+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);
+
+	if (size == I2C_SMBUS_QUICK)
+		read_write = I2C_SMBUS_WRITE;
+
+	switch (size) {
+	case I2C_SMBUS_QUICK:
+	case I2C_SMBUS_BYTE:
+	case I2C_SMBUS_BYTE_DATA:
+	case I2C_SMBUS_WORD_DATA:
+		zx2967_smbus_xfer_prepare(zx_i2c, addr, read_write,
+					  command, size, data);
+		break;
+	default:
+		dev_warn(&adap->dev, "Unsupported transaction %d\n", size);
+		return -EOPNOTSUPP;
+	}
+
+	if (read_write == I2C_SMBUS_READ)
+		return zx2967_smbus_xfer_read(zx_i2c, size, data);
+
+	return zx2967_smbus_xfer_write(zx_i2c);
+}
+
+#define ZX2967_I2C_FUNCS (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)
+
+static u32 zx2967_i2c_func(struct i2c_adapter *adap)
+{
+	return ZX2967_I2C_FUNCS;
+}
+
+static int __maybe_unused zx2967_i2c_suspend(struct device *dev)
+{
+	struct zx2967_i2c_info *zx_i2c = dev_get_drvdata(dev);
+
+	zx_i2c->is_suspended = true;
+	clk_disable_unprepare(zx_i2c->clk);
+
+	return 0;
+}
+
+static int __maybe_unused 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 SIMPLE_DEV_PM_OPS(zx2967_i2c_dev_pm_ops,
+			 zx2967_i2c_suspend, zx2967_i2c_resume);
+
+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 zx2967_i2c_info *zx_i2c;
+	void __iomem *reg_base;
+	struct resource *res;
+	struct clk *clk;
+	int ret;
+
+	zx_i2c = devm_kzalloc(&pdev->dev, sizeof(*zx_i2c), GFP_KERNEL);
+	if (!zx_i2c)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	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;
+	}
+
+	ret = device_property_read_u32(&pdev->dev, "clock-frequency",
+				       &zx_i2c->clk_freq);
+	if (ret) {
+		dev_err(&pdev->dev, "missing clock-frequency");
+		return ret;
+	}
+
+	ret = platform_get_irq(pdev, 0);
+	if (ret < 0)
+		return ret;
+
+	zx_i2c->irq = ret;
+	zx_i2c->reg_base = reg_base;
+	zx_i2c->clk = clk;
+
+	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 err_clk_unprepare;
+	}
+
+	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 err_clk_unprepare;
+	}
+
+	i2c_set_adapdata(&zx_i2c->adap, zx_i2c);
+	strlcpy(zx_i2c->adap.name, "zx2967 i2c adapter",
+		sizeof(zx_i2c->adap.name));
+	zx_i2c->adap.algo = &zx2967_i2c_algo;
+	zx_i2c->adap.nr = pdev->id;
+	zx_i2c->adap.dev.parent = &pdev->dev;
+	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 err_clk_unprepare;
+	}
+
+	return 0;
+err_clk_unprepare:
+	clk_disable_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_disable_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 v7 3/3] i2c: zx2967: add i2c controller driver for ZTE's zx2967 family

[Jun Nie]

2017-02-16 14:00 GMT+08:00 Baoyou Xie <baoyou.xie@linaro.org>:
> This patch adds i2c controller driver for ZTE's zx2967 family.
>
> Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
> Reviewed-by: Shawn Guo <shawnguo@kernel.org>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

Reviewed-by: Jun Nie <jun.nie@linaro.org>

Re: [PATCH v7 3/3] i2c: zx2967: add i2c controller driver for ZTE's zx2967 family

[Jun Nie]

2017-02-16 14:00 GMT+08:00 Baoyou Xie <baoyou.xie-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>:
> This patch adds i2c controller driver for ZTE's zx2967 family.
>
> Signed-off-by: Baoyou Xie <baoyou.xie-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> Reviewed-by: Shawn Guo <shawnguo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> Reviewed-by: Andy Shevchenko <andy.shevchenko-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

Reviewed-by: Jun Nie <jun.nie-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
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[PATCH v7 3/3] i2c: zx2967: add i2c controller driver for ZTE's zx2967 family

[Jun Nie]

2017-02-16 14:00 GMT+08:00 Baoyou Xie <baoyou.xie@linaro.org>:
> This patch adds i2c controller driver for ZTE's zx2967 family.
>
> Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
> Reviewed-by: Shawn Guo <shawnguo@kernel.org>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

Reviewed-by: Jun Nie <jun.nie@linaro.org>

Re: [PATCH v7 3/3] i2c: zx2967: add i2c controller driver for ZTE's zx2967 family

[Wolfram Sang]

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> +static int
> +zx2967_i2c_xfer_read_bytes(struct zx2967_i2c_info *zx_i2c, u32 bytes)
> +{
> +	unsigned long time_left;
> +
> +	reinit_completion(&zx_i2c->complete);
> +	zx2967_i2c_writel(zx_i2c, bytes - 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(DEV(zx_i2c), "read i2c transfer timed out\n");
> +		disable_irq(zx_i2c->irq);
> +		zx2967_i2c_reset_hardware(zx_i2c);
> +		return -EIO;
> +	}
> +
> +	return zx2967_i2c_empty_rx_fifo(zx_i2c, bytes);
> +}

Timeouts do happen on an I2C bus (e.g. when an EEPROM is in an erase
cycle). Or try 'i2cdetect -r'. At least, the dev_err should go. But I
also wonder if you really need to reset the hardware?

> +static int zx2967_i2c_xfer_read(struct zx2967_i2c_info *zx_i2c)
> +{
> +	int ret;
> +	int i;
> +
> +	for (i = 0; i < zx_i2c->access_cnt; i++) {
> +		ret = zx2967_i2c_xfer_read_bytes(zx_i2c, I2C_FIFO_MAX);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	if (zx_i2c->residue > 0) {
> +		ret = zx2967_i2c_xfer_read_bytes(zx_i2c, zx_i2c->residue);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	zx_i2c->residue = 0;
> +	zx_i2c->access_cnt = 0;
> +	return 0;
> +}
> +

This function...

> +static int zx2967_i2c_xfer_write(struct zx2967_i2c_info *zx_i2c)
> +{
> +	int ret;
> +	int i;
> +
> +	for (i = 0; i < zx_i2c->access_cnt; i++) {
> +		ret = zx2967_i2c_xfer_write_bytes(zx_i2c, I2C_FIFO_MAX);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	if (zx_i2c->residue > 0) {
> +		ret = zx2967_i2c_xfer_write_bytes(zx_i2c, zx_i2c->residue);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	zx_i2c->residue = 0;
> +	zx_i2c->access_cnt = 0;
> +	return 0;
> +}

... and this are one example where the read- and write-counterparts are
very similar. I wonder if we would do better having just one function
and handle the difference with some if(). Example here: If you'd unify
zx2967_i2c_xfer_write_bytes() and zx2967_i2c_xfer_read_bytes() into one
generic function then zx2967_i2c_xfer_write() and zx2967_i2c_xfer_read
automatically become identical AFAICS. Thoughts?

   Wolfram


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Re: [PATCH v7 3/3] i2c: zx2967: add i2c controller driver for ZTE's zx2967 family

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 2145 bytes --]


> +static int
> +zx2967_i2c_xfer_read_bytes(struct zx2967_i2c_info *zx_i2c, u32 bytes)
> +{
> +	unsigned long time_left;
> +
> +	reinit_completion(&zx_i2c->complete);
> +	zx2967_i2c_writel(zx_i2c, bytes - 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(DEV(zx_i2c), "read i2c transfer timed out\n");
> +		disable_irq(zx_i2c->irq);
> +		zx2967_i2c_reset_hardware(zx_i2c);
> +		return -EIO;
> +	}
> +
> +	return zx2967_i2c_empty_rx_fifo(zx_i2c, bytes);
> +}

Timeouts do happen on an I2C bus (e.g. when an EEPROM is in an erase
cycle). Or try 'i2cdetect -r'. At least, the dev_err should go. But I
also wonder if you really need to reset the hardware?

> +static int zx2967_i2c_xfer_read(struct zx2967_i2c_info *zx_i2c)
> +{
> +	int ret;
> +	int i;
> +
> +	for (i = 0; i < zx_i2c->access_cnt; i++) {
> +		ret = zx2967_i2c_xfer_read_bytes(zx_i2c, I2C_FIFO_MAX);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	if (zx_i2c->residue > 0) {
> +		ret = zx2967_i2c_xfer_read_bytes(zx_i2c, zx_i2c->residue);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	zx_i2c->residue = 0;
> +	zx_i2c->access_cnt = 0;
> +	return 0;
> +}
> +

This function...

> +static int zx2967_i2c_xfer_write(struct zx2967_i2c_info *zx_i2c)
> +{
> +	int ret;
> +	int i;
> +
> +	for (i = 0; i < zx_i2c->access_cnt; i++) {
> +		ret = zx2967_i2c_xfer_write_bytes(zx_i2c, I2C_FIFO_MAX);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	if (zx_i2c->residue > 0) {
> +		ret = zx2967_i2c_xfer_write_bytes(zx_i2c, zx_i2c->residue);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	zx_i2c->residue = 0;
> +	zx_i2c->access_cnt = 0;
> +	return 0;
> +}

... and this are one example where the read- and write-counterparts are
very similar. I wonder if we would do better having just one function
and handle the difference with some if(). Example here: If you'd unify
zx2967_i2c_xfer_write_bytes() and zx2967_i2c_xfer_read_bytes() into one
generic function then zx2967_i2c_xfer_write() and zx2967_i2c_xfer_read
automatically become identical AFAICS. Thoughts?

   Wolfram


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[PATCH v7 3/3] i2c: zx2967: add i2c controller driver for ZTE's zx2967 family

[Wolfram Sang]

> +static int
> +zx2967_i2c_xfer_read_bytes(struct zx2967_i2c_info *zx_i2c, u32 bytes)
> +{
> +	unsigned long time_left;
> +
> +	reinit_completion(&zx_i2c->complete);
> +	zx2967_i2c_writel(zx_i2c, bytes - 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(DEV(zx_i2c), "read i2c transfer timed out\n");
> +		disable_irq(zx_i2c->irq);
> +		zx2967_i2c_reset_hardware(zx_i2c);
> +		return -EIO;
> +	}
> +
> +	return zx2967_i2c_empty_rx_fifo(zx_i2c, bytes);
> +}

Timeouts do happen on an I2C bus (e.g. when an EEPROM is in an erase
cycle). Or try 'i2cdetect -r'. At least, the dev_err should go. But I
also wonder if you really need to reset the hardware?

> +static int zx2967_i2c_xfer_read(struct zx2967_i2c_info *zx_i2c)
> +{
> +	int ret;
> +	int i;
> +
> +	for (i = 0; i < zx_i2c->access_cnt; i++) {
> +		ret = zx2967_i2c_xfer_read_bytes(zx_i2c, I2C_FIFO_MAX);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	if (zx_i2c->residue > 0) {
> +		ret = zx2967_i2c_xfer_read_bytes(zx_i2c, zx_i2c->residue);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	zx_i2c->residue = 0;
> +	zx_i2c->access_cnt = 0;
> +	return 0;
> +}
> +

This function...

> +static int zx2967_i2c_xfer_write(struct zx2967_i2c_info *zx_i2c)
> +{
> +	int ret;
> +	int i;
> +
> +	for (i = 0; i < zx_i2c->access_cnt; i++) {
> +		ret = zx2967_i2c_xfer_write_bytes(zx_i2c, I2C_FIFO_MAX);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	if (zx_i2c->residue > 0) {
> +		ret = zx2967_i2c_xfer_write_bytes(zx_i2c, zx_i2c->residue);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	zx_i2c->residue = 0;
> +	zx_i2c->access_cnt = 0;
> +	return 0;
> +}

... and this are one example where the read- and write-counterparts are
very similar. I wonder if we would do better having just one function
and handle the difference with some if(). Example here: If you'd unify
zx2967_i2c_xfer_write_bytes() and zx2967_i2c_xfer_read_bytes() into one
generic function then zx2967_i2c_xfer_write() and zx2967_i2c_xfer_read
automatically become identical AFAICS. Thoughts?

   Wolfram

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