Date:   Thu, 15 Jun 2017 19:30:08 +0800
From:   Baolin Wang <baolin.wang@...eadtrum.com>
To:     <wsa@...-dreams.de>, <mark.rutland@....com>, <robh+dt@...nel.org>
CC:     <linux-i2c@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <broonie@...nel.org>,
        <baolin.wang@...aro.org>, <baolin.wang@...eadtrum.com>
Subject: [PATCH 2/2] i2c: Add Spreadtrum I2C controller driver

This patch adds the I2C controller driver for Spreadtrum platform.

Signed-off-by: Baolin Wang <baolin.wang@...eadtrum.com>
---
 drivers/i2c/busses/Kconfig    |   10 +
 drivers/i2c/busses/Makefile   |    1 +
 drivers/i2c/busses/i2c-sprd.c |  691 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 702 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-sprd.c

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 8adc0f1..dfbc301 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -877,6 +877,16 @@ config I2C_SIRF
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-sirf.
 
+config I2C_SPRD
+	tristate "Spreadtrum I2C interface"
+	depends on ARCH_SPRD
+	help
+	  If you say yes to this option, support will be included for the
+	  Spreadtrum I2C interface.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-sprd.
+
 config I2C_ST
 	tristate "STMicroelectronics SSC I2C support"
 	depends on ARCH_STI
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 30b6085..dd46c21 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -84,6 +84,7 @@ obj-$(CONFIG_I2C_SH7760)	+= i2c-sh7760.o
 obj-$(CONFIG_I2C_SH_MOBILE)	+= i2c-sh_mobile.o
 obj-$(CONFIG_I2C_SIMTEC)	+= i2c-simtec.o
 obj-$(CONFIG_I2C_SIRF)		+= i2c-sirf.o
+obj-$(CONFIG_I2C_SPRD)		+= i2c-sprd.o
 obj-$(CONFIG_I2C_ST)		+= i2c-st.o
 obj-$(CONFIG_I2C_STM32F4)	+= i2c-stm32f4.o
 obj-$(CONFIG_I2C_STU300)	+= i2c-stu300.o
diff --git a/drivers/i2c/busses/i2c-sprd.c b/drivers/i2c/busses/i2c-sprd.c
new file mode 100644
index 0000000..16d3e2c
--- /dev/null
+++ b/drivers/i2c/busses/i2c-sprd.c
@@ -0,0 +1,691 @@
+/*
+ * Copyright (C) 2017 Spreadtrum Communications Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/slab.h>
+
+#define I2C_CTL			0x0
+#define I2C_ADDR_CFG		0x4
+#define I2C_COUNT		0x8
+#define I2C_RX			0xC
+#define I2C_TX			0x10
+#define I2C_STATUS		0x14
+#define I2C_HSMODE_CFG		0x18
+#define I2C_VERSION		0x1C
+#define ADDR_DVD0		0x20
+#define ADDR_DVD1		0x24
+#define ADDR_STA0_DVD		0x28
+#define ADDR_RST		0x2C
+
+/* I2C_CTL */
+#define STP_EN			BIT(20)
+#define FIFO_AF_LVL		16
+#define FIFO_AE_LVL		12
+#define I2C_DMA_EN		BIT(11)
+#define FULL_INTEN		BIT(10)
+#define EMPTY_INTEN		BIT(9)
+#define I2C_DVD_OPT		BIT(8)
+#define I2C_OUT_OPT		BIT(7)
+#define I2C_TRIM_OPT		BIT(6)
+#define I2C_HS_MODE		BIT(4)
+#define I2C_MODE		BIT(3)
+#define I2C_EN			BIT(2)
+#define I2C_INT_EN		BIT(1)
+#define I2C_START		BIT(0)
+
+/* I2C_STATUS */
+#define SDA_IN			BIT(21)
+#define SCL_IN			BIT(20)
+#define FIFO_FULL		BIT(4)
+#define FIFO_EMPTY		BIT(3)
+#define I2C_INT			BIT(2)
+#define I2C_RX_ACK		BIT(1)
+#define I2C_BUSY		BIT(0)
+
+/* ADDR_RST */
+#define I2C_RST			BIT(0)
+
+#define I2C_FIFO_DEEP		12
+#define I2C_FIFO_FULL_THLD	15
+#define I2C_FIFO_EMPTY_THLD	4
+#define I2C_DATA_STEP		8
+#define SPRD_I2C_TIMEOUT	(msecs_to_jiffies(1000))
+
+/* timeout (ms) for pm runtime autosuspend */
+#define SPRD_I2C_PM_TIMEOUT	1000
+
+/* SPRD i2c data structure */
+struct sprd_i2c {
+	struct i2c_adapter adap;
+	struct device *dev;
+	void __iomem *base;
+	struct i2c_msg *msg;
+	struct clk *clk;
+	unsigned int src_clk;
+	unsigned int bus_freq;
+	struct completion complete;
+	u8 *buf;
+	u16 count;
+	int irq;
+	int err;
+};
+
+static void sprd_i2c_dump_reg(struct sprd_i2c *i2c_dev)
+{
+	dev_err(&i2c_dev->adap.dev, ": ======dump i2c-%d reg=======\n",
+		i2c_dev->adap.nr);
+	dev_err(&i2c_dev->adap.dev, ": I2C_CTRL:0x%x\n",
+		readl(i2c_dev->base + I2C_CTL));
+	dev_err(&i2c_dev->adap.dev, ": I2C_ADDR_CFG:0x%x\n",
+		readl(i2c_dev->base + I2C_ADDR_CFG));
+	dev_err(&i2c_dev->adap.dev, ": I2C_COUNT:0x%x\n",
+		readl(i2c_dev->base + I2C_COUNT));
+	dev_err(&i2c_dev->adap.dev, ": I2C_RX:0x%x\n",
+		readl(i2c_dev->base + I2C_RX));
+	dev_err(&i2c_dev->adap.dev, ": I2C_STATUS:0x%x\n",
+		readl(i2c_dev->base + I2C_STATUS));
+	dev_err(&i2c_dev->adap.dev, ": ADDR_DVD0:0x%x\n",
+		readl(i2c_dev->base + ADDR_DVD0));
+	dev_err(&i2c_dev->adap.dev, ": ADDR_DVD1:0x%x\n",
+		readl(i2c_dev->base + ADDR_DVD1));
+	dev_err(&i2c_dev->adap.dev, ": ADDR_STA0_DVD:0x%x\n",
+		readl(i2c_dev->base + ADDR_STA0_DVD));
+	dev_err(&i2c_dev->adap.dev, ": ADDR_RST:0x%x\n",
+		readl(i2c_dev->base + ADDR_RST));
+}
+
+static void sprd_i2c_set_count(struct sprd_i2c *i2c_dev, u32 count)
+{
+	writel(count, i2c_dev->base + I2C_COUNT);
+}
+
+static void sprd_i2c_send_stop(struct sprd_i2c *i2c_dev, int stop)
+{
+	unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
+
+	if (stop)
+		writel(tmp & (~STP_EN), i2c_dev->base + I2C_CTL);
+	else
+		writel(tmp | STP_EN, i2c_dev->base + I2C_CTL);
+}
+
+static void sprd_i2c_clear_start(struct sprd_i2c *i2c_dev)
+{
+	unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
+
+	writel(tmp & (~I2C_START), i2c_dev->base + I2C_CTL);
+}
+
+static void sprd_i2c_clear_ack(struct sprd_i2c *i2c_dev)
+{
+	unsigned int tmp = readl(i2c_dev->base + I2C_STATUS);
+
+	writel(tmp & (~I2C_RX_ACK), i2c_dev->base + I2C_STATUS);
+}
+
+static void sprd_i2c_clear_irq(struct sprd_i2c *i2c_dev)
+{
+	unsigned int tmp = readl(i2c_dev->base + I2C_STATUS);
+
+	writel(tmp & (~I2C_INT), i2c_dev->base + I2C_STATUS);
+}
+
+static void sprd_i2c_reset_fifo(struct sprd_i2c *i2c_dev)
+{
+	writel(I2C_RST, i2c_dev->base + ADDR_RST);
+}
+
+static void sprd_i2c_set_devaddr(struct sprd_i2c *i2c_dev, struct i2c_msg *m)
+{
+	writel(m->addr << 1, i2c_dev->base + I2C_ADDR_CFG);
+}
+
+static void sprd_i2c_write_bytes(struct sprd_i2c *i2c_dev, u8 *buf, u32 len)
+{
+	u32 i = 0;
+
+	for (i = 0; i < len; i++) {
+		writel(buf[i], i2c_dev->base + I2C_TX);
+		dev_dbg(&i2c_dev->adap.dev, "write bytes[%d] = %x\n", i, buf[i]);
+	}
+}
+
+static void sprd_i2c_read_bytes(struct sprd_i2c *i2c_dev, u8 *buf, u16 len)
+{
+	u32 i = 0;
+
+	for (i = 0; i < len; i++) {
+		buf[i] = readl(i2c_dev->base + I2C_RX);
+		dev_dbg(&i2c_dev->adap.dev, "read bytes[%d] = %x\n", i, buf[i]);
+	}
+}
+
+static void sprd_i2c_set_full_thld(struct sprd_i2c *i2c_dev, u32 full_thld)
+{
+	unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
+
+	tmp &= ~(0xf << FIFO_AF_LVL);
+	tmp |= (full_thld << FIFO_AF_LVL);
+	writel(tmp, i2c_dev->base + I2C_CTL);
+};
+
+static void sprd_i2c_set_empty_thld(struct sprd_i2c *i2c_dev, u32 empty_thld)
+{
+	unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
+
+	tmp &= ~(0xf << FIFO_AE_LVL);
+	tmp |= (empty_thld << FIFO_AE_LVL);
+	writel(tmp, i2c_dev->base + I2C_CTL);
+};
+
+static void sprd_i2c_set_fifo_full_int(struct sprd_i2c *i2c_dev, int enable)
+{
+	unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
+
+	if (enable)
+		tmp |= FULL_INTEN;
+	else
+		tmp &= ~FULL_INTEN;
+
+	writel(tmp, i2c_dev->base + I2C_CTL);
+};
+
+static void sprd_i2c_set_fifo_empty_int(struct sprd_i2c *i2c_dev, int enable)
+{
+	unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
+
+	if (enable)
+		tmp |= EMPTY_INTEN;
+	else
+		tmp &= ~EMPTY_INTEN;
+
+	writel(tmp, i2c_dev->base + I2C_CTL);
+};
+
+static void sprd_i2c_opt_start(struct sprd_i2c *i2c_dev)
+{
+	unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
+
+	writel(tmp | I2C_START, i2c_dev->base + I2C_CTL);
+}
+
+static void sprd_i2c_opt_mode(struct sprd_i2c *i2c_dev, int rw)
+{
+	unsigned int cmd = readl(i2c_dev->base + I2C_CTL) & (~I2C_MODE);
+
+	writel((cmd | rw << 3), i2c_dev->base + I2C_CTL);
+}
+
+static void sprd_i2c_data_transfer(struct sprd_i2c *i2c_dev)
+{
+	u32 i2c_count = i2c_dev->count;
+	u32 need_tran = i2c_count <= I2C_FIFO_DEEP ? i2c_count : I2C_FIFO_DEEP;
+	struct i2c_msg *msg = i2c_dev->msg;
+
+	if ((msg->flags & I2C_M_RD)) {
+		sprd_i2c_read_bytes(i2c_dev, i2c_dev->buf, I2C_FIFO_FULL_THLD);
+		i2c_dev->count -= I2C_FIFO_FULL_THLD;
+		i2c_dev->buf += I2C_FIFO_FULL_THLD;
+
+		/*
+		 * If the read data count is larger than rx fifo full threshold,
+		 * we should enable the rx fifo full interrupt to read data
+		 * again.
+		 */
+		if (i2c_dev->count >= I2C_FIFO_FULL_THLD)
+			sprd_i2c_set_fifo_full_int(i2c_dev, 1);
+	} else {
+		sprd_i2c_write_bytes(i2c_dev, i2c_dev->buf, need_tran);
+		i2c_dev->buf += need_tran;
+		i2c_dev->count -= need_tran;
+
+		/*
+		 * If the write data count is arger than tx fifo depth which
+		 * means we can not write all data in one time, then we should
+		 * enable the tx fifo empty interrupt to write again.
+		 */
+		if (i2c_count > I2C_FIFO_DEEP)
+			sprd_i2c_set_fifo_empty_int(i2c_dev, 1);
+	}
+}
+
+static int sprd_i2c_handle_msg(struct i2c_adapter *i2c_adap,
+			       struct i2c_msg *msg, int is_last_msg)
+{
+	struct sprd_i2c *i2c_dev = i2c_adap->algo_data;
+
+	i2c_dev->msg = msg;
+	i2c_dev->buf = msg->buf;
+	i2c_dev->count = msg->len;
+
+	reinit_completion(&i2c_dev->complete);
+	/* Reset rx/tx fifos */
+	sprd_i2c_reset_fifo(i2c_dev);
+	/* Set device address */
+	sprd_i2c_set_devaddr(i2c_dev, msg);
+	/* Set I2C read or write bytes count */
+	sprd_i2c_set_count(i2c_dev, msg->len);
+
+	if ((msg->flags & I2C_M_RD)) {
+		/* Set read operation */
+		sprd_i2c_opt_mode(i2c_dev, 1);
+		/* Last byte transmission should excute stop operation */
+		sprd_i2c_send_stop(i2c_dev, 1);
+	} else {
+		/* Set write operation */
+		sprd_i2c_opt_mode(i2c_dev, 0);
+
+		/* Last byte transmission should excute stop operation */
+		if (is_last_msg)
+			sprd_i2c_send_stop(i2c_dev, 1);
+		else
+			sprd_i2c_send_stop(i2c_dev, 0);
+	}
+
+	/*
+	 * We should enable rx fifo full interrupt to get data when receiving
+	 * full data.
+	 */
+	if ((msg->flags & I2C_M_RD))
+		sprd_i2c_set_fifo_full_int(i2c_dev, 1);
+	else
+		sprd_i2c_data_transfer(i2c_dev);
+
+	/* Start to transmit */
+	sprd_i2c_opt_start(i2c_dev);
+
+	wait_for_completion(&i2c_dev->complete);
+
+	return i2c_dev->err;
+}
+
+static int sprd_i2c_master_xfer(struct i2c_adapter *i2c_adap,
+				struct i2c_msg *msgs, int num)
+{
+	struct sprd_i2c *i2c_dev = i2c_adap->algo_data;
+	int im, ret;
+
+	ret = pm_runtime_get_sync(i2c_dev->dev);
+	if (ret < 0)
+		return ret;
+
+	for (im = 0; im != num; im++)
+		ret = sprd_i2c_handle_msg(i2c_adap, &msgs[im], im == num - 1);
+
+	pm_runtime_mark_last_busy(i2c_dev->dev);
+	pm_runtime_put_autosuspend(i2c_dev->dev);
+
+	return (ret >= 0) ? im : ret;
+}
+
+static u32 sprd_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm sprd_i2c_algo = {
+	.master_xfer = sprd_i2c_master_xfer,
+	.functionality = sprd_i2c_func,
+};
+
+static void sprd_i2c_set_clk(struct sprd_i2c *i2c_dev, unsigned int freq)
+{
+	u32 apb_clk = i2c_dev->src_clk;
+	u32 i2c_dvd = apb_clk / (4 * freq) - 1;
+	u32 high = ((i2c_dvd << 1) * 2) / 5;
+	u32 low = ((i2c_dvd << 1) * 3) / 5;
+	u32 div0 = (high & 0xffff) << 16 | (low & 0xffff);
+	u32 div1 =  (high & 0xffff0000) | ((low & 0xffff0000) >> 16);
+
+	writel(div0, i2c_dev->base + ADDR_DVD0);
+	writel(div1, i2c_dev->base + ADDR_DVD1);
+
+	if (freq == 400000)
+		writel((6 * apb_clk) / 10000000, i2c_dev->base + ADDR_STA0_DVD);
+	else if (freq == 100000)
+		writel((4 * apb_clk) / 1000000, i2c_dev->base + ADDR_STA0_DVD);
+}
+
+static void __maybe_unused sprd_i2c_enable(struct sprd_i2c *i2c_dev)
+{
+	unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
+
+	tmp &= ~(I2C_EN | I2C_TRIM_OPT | (0xF << FIFO_AF_LVL) |
+		 (0xF << FIFO_AE_LVL));
+	tmp |= I2C_INT_EN | I2C_DVD_OPT;
+	writel(tmp, i2c_dev->base + I2C_CTL);
+
+	/* Set rx fifo full data threshold */
+	sprd_i2c_set_full_thld(i2c_dev, I2C_FIFO_FULL_THLD);
+	/* Set tx fifo empty data threshold */
+	sprd_i2c_set_empty_thld(i2c_dev, I2C_FIFO_EMPTY_THLD);
+
+	sprd_i2c_set_clk(i2c_dev, i2c_dev->bus_freq);
+	/* Reset rx/tx fifo */
+	sprd_i2c_reset_fifo(i2c_dev);
+	sprd_i2c_clear_irq(i2c_dev);
+
+	/* Enable I2C module */
+	tmp = readl(i2c_dev->base + I2C_CTL);
+	writel(tmp | I2C_EN, i2c_dev->base + I2C_CTL);
+}
+
+static irqreturn_t sprd_i2c_isr_thread(int irq, void *dev_id)
+{
+	struct sprd_i2c *i2c_dev = dev_id;
+	struct i2c_msg *msg = i2c_dev->msg;
+	int ack = readl(i2c_dev->base + I2C_STATUS) & I2C_RX_ACK;
+	u32 i2c_count = readl(i2c_dev->base + I2C_COUNT);
+	u32 i2c_tran;
+
+	if (msg->flags & I2C_M_RD)
+		i2c_tran = i2c_dev->count >= I2C_FIFO_FULL_THLD;
+	else
+		i2c_tran = i2c_count;
+
+	/*
+	 * If we got one ACK from slave when writing data, and we did not
+	 * finish this transmission (i2c_tran is not zero), then we should
+	 * continue to write data.
+	 *
+	 * For reading data, ack is always 0, if i2c_tran is not 0 which
+	 * means we still need to contine to read data from slave.
+	 */
+	if (i2c_tran && !ack) {
+		sprd_i2c_data_transfer(i2c_dev);
+		return IRQ_HANDLED;
+	}
+
+	i2c_dev->err = 0;
+
+	/*
+	 * If we did not get one ACK from slave when writing data, we should
+	 * dump all registers to check I2C status.
+	 */
+	if (ack) {
+		i2c_dev->err = -EIO;
+		sprd_i2c_dump_reg(i2c_dev);
+	} else if (msg->flags & I2C_M_RD && i2c_dev->count) {
+		sprd_i2c_read_bytes(i2c_dev, i2c_dev->buf, i2c_dev->count);
+	}
+
+	/* Transmission is done and clear ack and start operation */
+	sprd_i2c_clear_ack(i2c_dev);
+	sprd_i2c_clear_start(i2c_dev);
+	complete(&i2c_dev->complete);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t sprd_i2c_isr(int irq, void *dev_id)
+{
+	struct sprd_i2c *i2c_dev = dev_id;
+	struct i2c_msg *msg = i2c_dev->msg;
+	u32 i2c_count = readl(i2c_dev->base + I2C_COUNT);
+	int ack = readl(i2c_dev->base + I2C_STATUS) & I2C_RX_ACK;
+	u32 i2c_tran;
+
+	if (msg->flags & I2C_M_RD)
+		i2c_tran = i2c_dev->count >= I2C_FIFO_FULL_THLD;
+	else
+		i2c_tran = i2c_count;
+
+	/*
+	 * If ack == 0 means we got one ACK, if ack != 0 means we did not
+	 * get one ACK from slave when writing data, then we should finish
+	 * this transmission since we got some errors.
+	 *
+	 * When writing data, if i2c_tran == 0 which means we have writen
+	 * done all data, then we can finish this transmission.
+	 *
+	 * When reading data, if conut < rx fifo full threshold, which
+	 * means we can read all data in one time, then we can finish this
+	 * transmission too.
+	 */
+	if (!i2c_tran || ack) {
+		sprd_i2c_clear_start(i2c_dev);
+		sprd_i2c_clear_irq(i2c_dev);
+	}
+
+	/* Clear rx/tx fifo interrupts */
+	sprd_i2c_set_fifo_empty_int(i2c_dev, 0);
+	sprd_i2c_set_fifo_full_int(i2c_dev, 0);
+
+	return IRQ_WAKE_THREAD;
+}
+
+static int sprd_i2c_clk_init(struct sprd_i2c *i2c_dev)
+{
+	struct clk *clk_i2c, *clk_parent;
+	struct device_node *np = i2c_dev->adap.dev.of_node;
+
+	clk_i2c = of_clk_get_by_name(np, "i2c");
+	if (IS_ERR(clk_i2c)) {
+		dev_warn(&i2c_dev->adap.dev, "i2c%d can't get the i2c clock\n",
+			 i2c_dev->adap.nr);
+		clk_i2c = NULL;
+	}
+
+	clk_parent = of_clk_get_by_name(np, "source");
+	if (IS_ERR(clk_parent)) {
+		dev_warn(&i2c_dev->adap.dev,
+			 "i2c%d can't get the source clock\n",
+			 i2c_dev->adap.nr);
+		clk_parent = NULL;
+	}
+
+	if (clk_set_parent(clk_i2c, clk_parent))
+		i2c_dev->src_clk = clk_get_rate(clk_i2c);
+	else
+		i2c_dev->src_clk = 26000000;
+
+	dev_dbg(&i2c_dev->adap.dev, "i2c%d set source clock is %d\n",
+		i2c_dev->adap.nr, i2c_dev->src_clk);
+
+	i2c_dev->clk = of_clk_get_by_name(np, "enable");
+	if (IS_ERR(i2c_dev->clk)) {
+		dev_warn(&i2c_dev->adap.dev,
+			 "i2c%d can't get the enable clock\n",
+			 i2c_dev->adap.nr);
+		i2c_dev->clk = NULL;
+	}
+
+	return 0;
+}
+
+static int sprd_i2c_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct sprd_i2c *i2c_dev;
+	struct resource *res;
+	u32 prop;
+	int ret;
+
+	pdev->id = of_alias_get_id(dev->of_node, "i2c");
+
+	i2c_dev = devm_kzalloc(dev, sizeof(struct sprd_i2c), GFP_KERNEL);
+	if (!i2c_dev)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	i2c_dev->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(i2c_dev->base))
+		return PTR_ERR(i2c_dev->base);
+
+	i2c_dev->irq = platform_get_irq(pdev, 0);
+	if (i2c_dev->irq < 0) {
+		dev_err(&pdev->dev, "failed to get irq resource\n");
+		return -ENXIO;
+	}
+
+	i2c_set_adapdata(&i2c_dev->adap, i2c_dev);
+	init_completion(&i2c_dev->complete);
+	snprintf(i2c_dev->adap.name, sizeof(i2c_dev->adap.name),
+		 "%s", "sprd-i2c");
+
+	i2c_dev->bus_freq = 100000;
+	i2c_dev->adap.owner = THIS_MODULE;
+	i2c_dev->dev = dev;
+	i2c_dev->adap.retries = 3;
+	i2c_dev->adap.algo = &sprd_i2c_algo;
+	i2c_dev->adap.algo_data = i2c_dev;
+	i2c_dev->adap.dev.parent = dev;
+	i2c_dev->adap.nr = pdev->id;
+	i2c_dev->adap.dev.of_node = dev->of_node;
+
+	if (!of_property_read_u32(dev->of_node, "clock-frequency", &prop))
+		i2c_dev->bus_freq = prop;
+
+	sprd_i2c_clk_init(i2c_dev);
+	platform_set_drvdata(pdev, i2c_dev);
+
+	pm_runtime_set_autosuspend_delay(i2c_dev->dev, SPRD_I2C_PM_TIMEOUT);
+	pm_runtime_use_autosuspend(i2c_dev->dev);
+	pm_runtime_set_active(i2c_dev->dev);
+	pm_runtime_enable(i2c_dev->dev);
+
+	ret = pm_runtime_get_sync(i2c_dev->dev);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "i2c%d pm runtime resume failed!\n",
+			pdev->id);
+		return ret;
+	}
+
+	ret = devm_request_threaded_irq(dev, i2c_dev->irq,
+		sprd_i2c_isr, sprd_i2c_isr_thread,
+		IRQF_NO_SUSPEND | IRQF_ONESHOT,
+		pdev->name, i2c_dev);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to request irq %d\n", i2c_dev->irq);
+		goto error;
+	}
+
+	ret = i2c_add_numbered_adapter(&i2c_dev->adap);
+	if (ret) {
+		dev_err(&pdev->dev, "add adapter failed\n");
+		goto error;
+	}
+
+	pm_runtime_mark_last_busy(i2c_dev->dev);
+	pm_runtime_put_autosuspend(i2c_dev->dev);
+	return 0;
+
+error:
+	pm_runtime_put_noidle(i2c_dev->dev);
+	pm_runtime_disable(i2c_dev->dev);
+	return ret;
+}
+
+static int sprd_i2c_remove(struct platform_device *pdev)
+{
+	struct sprd_i2c *i2c_dev = platform_get_drvdata(pdev);
+	int ret;
+
+	ret = pm_runtime_get_sync(i2c_dev->dev);
+	if (ret < 0)
+		return ret;
+
+	i2c_del_adapter(&i2c_dev->adap);
+
+	if (!IS_ERR_OR_NULL(i2c_dev->clk))
+		clk_unprepare(i2c_dev->clk);
+
+	pm_runtime_put_noidle(i2c_dev->dev);
+	pm_runtime_disable(i2c_dev->dev);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int sprd_i2c_suspend_noirq(struct device *pdev)
+{
+	return pm_runtime_force_suspend(pdev);
+}
+
+static int sprd_i2c_resume_noirq(struct device *pdev)
+{
+	return pm_runtime_force_resume(pdev);
+}
+#endif  /* CONFIG_PM_SLEEP */
+
+#ifdef CONFIG_PM
+static int sprd_i2c_runtime_suspend(struct device *pdev)
+{
+	struct sprd_i2c *i2c_dev = dev_get_drvdata(pdev);
+
+	clk_disable_unprepare(i2c_dev->clk);
+
+	return 0;
+}
+
+static int sprd_i2c_runtime_resume(struct device *pdev)
+{
+	struct sprd_i2c *i2c_dev = dev_get_drvdata(pdev);
+
+	clk_prepare_enable(i2c_dev->clk);
+	sprd_i2c_enable(i2c_dev);
+
+	return 0;
+}
+#endif  /* CONFIG_PM */
+
+static const struct dev_pm_ops sprd_i2c_pm_ops = {
+	SET_RUNTIME_PM_OPS(sprd_i2c_runtime_suspend,
+			   sprd_i2c_runtime_resume, NULL)
+
+	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(sprd_i2c_suspend_noirq,
+				      sprd_i2c_resume_noirq)
+};
+
+static const struct of_device_id sprd_i2c_of_match[] = {
+	{ .compatible = "sprd,r8p0-i2c", },
+};
+MODULE_DEVICE_TABLE(of, sprd_i2c_of_match);
+
+static struct platform_driver sprd_i2c_driver = {
+	.probe = sprd_i2c_probe,
+	.remove = sprd_i2c_remove,
+	.driver = {
+		   .name = "sprd-i2c",
+		   .of_match_table = of_match_ptr(sprd_i2c_of_match),
+		   .pm = &sprd_i2c_pm_ops,
+	},
+};
+
+static int __init sprd_i2c_init(void)
+{
+	return platform_driver_register(&sprd_i2c_driver);
+}
+arch_initcall_sync(sprd_i2c_init);
+
+static void __exit sprd_i2c_exit(void)
+{
+	platform_driver_unregister(&sprd_i2c_driver);
+}
+module_exit(sprd_i2c_exit);
+
+MODULE_DESCRIPTION("Spreadtrum I2C bus adapter driver");
+MODULE_AUTHOR("Lanqing Liu <lanqing.liu@...eadtrum.com>");
+MODULE_LICENSE("GPL");
-- 
1.7.9.5

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