Message-ID: <1956748.HoDAyYWJMb@typ>
Date:	Mon, 19 May 2014 02:37:57 +0200
From:	Max Schwarz <max.schwarz@...ine.de>
To:	Wolfram Sang <wsa@...-dreams.de>
Cc:	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>, linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	Heiko Stübner <heiko@...ech.de>
Subject: [PATCH v3] i2c: add driver for Rockchip RK3xxx SoC I2C adapter

Driver for the native I2C adapter found in Rockchip RK3xxx SoCs.

Configuration is only possible through devicetree. The driver is
interrupt driven and supports the I2C_M_IGNORE_NAK mangling bit.

Signed-off-by: Max Schwarz <max.schwarz@...ine.de>
---

The driver cannot be used without a proper clock driver
supporting rate calculation, such as Heiko Stübner's RK3xxx clock
driver series [1].

Changes since v2:
  - support for the new GRF syscon mapping by Heiko Stübner
  - probe error handling improvements by Heiko Stübner
  - fixed wrong remove() order found by Heiko Stübner
  - removed unnecessary clk_enable() during probe
  - removed switch back to old interface during remove

Changes since v1:
  - dt property names "rockchip,*" suggested by Heiko Stübner
  - fixed overly specific RK3188 comment (Heiko Stübner)

The dts files needed for testing on Radxa Rock are in my tree at

https://github.com/xqms/linux.git topic/i2c-rk3x-clean-v3

[1]: http://www.spinics.net/lists/arm-kernel/msg329102.html

 Documentation/devicetree/bindings/i2c/i2c-rk3x.txt |  38 ++
 drivers/i2c/busses/Kconfig                         |  10 +
 drivers/i2c/busses/Makefile                        |   1 +
 drivers/i2c/busses/i2c-rk3x.c                      | 740 +++++++++++++++++++++
 4 files changed, 789 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/i2c-rk3x.txt
 create mode 100644 drivers/i2c/busses/i2c-rk3x.c

diff --git a/Documentation/devicetree/bindings/i2c/i2c-rk3x.txt b/Documentation/devicetree/bindings/i2c/i2c-rk3x.txt
new file mode 100644
index 0000000..99598f0
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-rk3x.txt
@@ -0,0 +1,38 @@
+* Rockchip RK3xxx I2C controller
+
+This driver interfaces with the native I2C controller present in Rockchip
+RK3xxx SoCs.
+
+Required properties :
+
+ - reg : Offset and length of the register set for the device
+ - compatible : should be "rockchip,rk3066-i2c", "rockchip,rk3188-i2c" or
+		"rockchip,rk3288-i2c".
+ - interrupts : interrupt number
+ - clocks : parent clock
+
+Required on RK3066, RK3188 :
+
+ - rockchip,grf : the phandle of the syscon node for the general register
+		  file (GRF)
+ - rockchip,bus-index : index of the bus in the GRF
+
+Optional properties :
+
+ - clock-frequency : SCL frequency to use (in Hz). If omitted, 100kHz is used.
+
+Example:
+
+i2c0: i2c@...2d000 {
+	compatible = "rockchip,rk3188-i2c";
+	reg = <0x2002d000 0x1000>;
+	interrupts = <GIC_SPI 40 IRQ_TYPE_LEVEL_HIGH>;
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	rockchip,grf = <&grf>;
+	rockchip,bus-index = <0>;
+
+	clock-names = "i2c";
+	clocks = <&cru PCLK_I2C0>;
+};
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index c94db1c..f973632 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -663,6 +663,16 @@ config I2C_PXA_SLAVE
 	  is necessary for systems where the PXA may be a target on the
 	  I2C bus.
 
+config I2C_RK3X
+	tristate "Rockchip RK3xxx I2C adapter"
+	depends on OF
+	help
+	  Say Y here to include support for the I2C adapter in Rockchip RK3xxx
+	  SoCs.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called i2c-rk3x.
+
 config I2C_QUP
 	tristate "Qualcomm QUP based I2C controller"
 	depends on ARCH_QCOM
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 18d18ff..39b6851 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -65,6 +65,7 @@ obj-$(CONFIG_I2C_PNX)		+= i2c-pnx.o
 obj-$(CONFIG_I2C_PUV3)		+= i2c-puv3.o
 obj-$(CONFIG_I2C_PXA)		+= i2c-pxa.o
 obj-$(CONFIG_I2C_PXA_PCI)	+= i2c-pxa-pci.o
+obj-$(CONFIG_I2C_RK3X)		+= i2c-rk3x.o
 obj-$(CONFIG_I2C_QUP)		+= i2c-qup.o
 obj-$(CONFIG_I2C_RIIC)		+= i2c-riic.o
 obj-$(CONFIG_I2C_S3C2410)	+= i2c-s3c2410.o
diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c
new file mode 100644
index 0000000..4f506f6
--- /dev/null
+++ b/drivers/i2c/busses/i2c-rk3x.c
@@ -0,0 +1,740 @@
+/*
+ * Driver for I2C adapter in Rockchip RK3xxx SoC
+ *
+ * Max Schwarz <max.schwarz@...ine.de>
+ * based on the patches by Rockchip Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#include <linux/i2c.h>
+#include <linux/time.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/spinlock.h>
+#include <linux/clk.h>
+#include <linux/wait.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+
+
+/* Register Map */
+#define REG_CON        0x00 /* control register */
+#define REG_CLKDIV     0x04 /* clock divisor register */
+#define REG_MRXADDR    0x08 /* slave address for REGISTER_TX */
+#define REG_MRXRADDR   0x0c /* slave register address for REGISTER_TX */
+#define REG_MTXCNT     0x10 /* number of bytes to be transmitted */
+#define REG_MRXCNT     0x14 /* number of bytes to be received */
+#define REG_IEN        0x18 /* interrupt enable */
+#define REG_IPD        0x1c /* interrupt pending */
+#define REG_FCNT       0x20 /* finished count */
+
+/* Data buffer offsets */
+#define TXBUFFER_BASE 0x100
+#define RXBUFFER_BASE 0x200
+
+/* REG_CON bits */
+#define REG_CON_EN        (1 << 0)
+enum {
+	REG_CON_MOD_TX = 0,      /* transmit data */
+	REG_CON_MOD_REGISTER_TX, /* select register and restart */
+	REG_CON_MOD_RX,          /* receive data */
+	REG_CON_MOD_REGISTER_RX, /* broken: transmits read addr AND writes
+				  * register addr */
+};
+#define REG_CON_MOD(mod)  ((mod) << 1)
+#define REG_CON_MOD_MASK  (3 << 1)
+#define REG_CON_START     (1 << 3)
+#define REG_CON_STOP      (1 << 4)
+#define REG_CON_LASTACK   (1 << 5) /* 1: do not send ACK after last receive */
+#define REG_CON_ACTACK    (1 << 6) /* 1: stop if NACK is received */
+
+/* REG_MRXADDR bits */
+#define REG_MRXADDR_LOW   (1 << 24) /* bits [7:0] of MRX[R]ADDR are valid */
+#define REG_MRXADDR_MID   (1 << 25) /* bits [15:8] of MRX[R]ADDR are valid */
+#define REG_MRXADDR_HIGH  (1 << 26) /* bits [23:16] of MRX[R]ADDR are valid */
+
+/* REG_IEN/REG_IPD bits */
+#define REG_INT_BTF       (1 << 0) /* a byte was transmitted */
+#define REG_INT_BRF       (1 << 1) /* a byte was received */
+#define REG_INT_MBTF      (1 << 2) /* master data transmit finished */
+#define REG_INT_MBRF      (1 << 3) /* master data receive finished */
+#define REG_INT_START     (1 << 4) /* START condition generated */
+#define REG_INT_STOP      (1 << 5) /* STOP condition generated */
+#define REG_INT_NAKRCV    (1 << 6) /* NACK received */
+#define REG_INT_ALL       0x7f
+
+/* Constants */
+#define WAIT_TIMEOUT      200 /* ms */
+
+enum rk3x_i2c_state {
+	STATE_IDLE,
+	STATE_START,
+	STATE_READ,
+	STATE_WRITE,
+	STATE_STOP
+};
+
+/**
+ * @grf_offset: offset inside the grf regmap for setting the i2c type
+ */
+struct rk3x_i2c_soc_data {
+	int grf_offset;
+};
+
+struct rk3x_i2c {
+	struct i2c_adapter adap;
+	struct device *dev;
+	struct rk3x_i2c_soc_data *soc_data;
+
+	/* Hardware resources */
+	void __iomem *regs;
+	struct regmap *grf;
+	unsigned int bus_index;
+	struct clk *clk;
+	int irq;
+
+	/* Settings */
+	unsigned int scl_frequency;
+
+	/* Synchronization & notification */
+	spinlock_t lock;
+	wait_queue_head_t wait;
+	bool busy;
+
+	/* Current message */
+	struct i2c_msg *msg;
+	u8 addr;
+	unsigned int mode;
+
+	/* I2C state machine */
+	enum rk3x_i2c_state state;
+	unsigned int processed; /* sent/received bytes */
+	int error;
+};
+
+static inline void i2c_writel(struct rk3x_i2c *i2c, u32 value,
+			      unsigned int offset)
+{
+	writel(value, i2c->regs + offset);
+}
+
+static inline u32 i2c_readl(struct rk3x_i2c *i2c, unsigned int offset)
+{
+	return readl(i2c->regs + offset);
+}
+
+/* Reset all interrupt pending bits */
+static inline void rk3x_i2c_clean_ipd(struct rk3x_i2c *i2c)
+{
+	i2c_writel(i2c, REG_INT_ALL, REG_IPD);
+}
+
+/**
+ * Generate a START condition, which triggers a REG_INT_START interrupt.
+ */
+static void rk3x_i2c_start(struct rk3x_i2c *i2c)
+{
+	u32 val;
+
+	rk3x_i2c_clean_ipd(i2c);
+	i2c_writel(i2c, REG_INT_START, REG_IEN);
+
+	/* enable adapter with correct mode, send START condition */
+	val = REG_CON_EN | REG_CON_MOD(i2c->mode) | REG_CON_START;
+
+	/* if we want to react to NACK, set ACTACK bit */
+	if (!(i2c->msg->flags & I2C_M_IGNORE_NAK))
+		val |= REG_CON_ACTACK;
+
+	i2c_writel(i2c, val, REG_CON);
+}
+
+/**
+ * Generate a STOP condition, which triggers a REG_INT_STOP interrupt.
+ *
+ * @error: Error code to return in rk3x_i2c_xfer
+ */
+static void rk3x_i2c_stop(struct rk3x_i2c *i2c, int error)
+{
+	unsigned int ctrl;
+
+	i2c->processed = 0;
+	i2c->msg = 0;
+	i2c->error = error;
+
+	/* Enable stop interrupt */
+	i2c_writel(i2c, REG_INT_STOP, REG_IEN);
+
+	i2c->state = STATE_STOP;
+
+	ctrl = i2c_readl(i2c, REG_CON);
+	ctrl |= REG_CON_STOP;
+	i2c_writel(i2c, ctrl, REG_CON);
+}
+
+/**
+ * Setup a read according to i2c->msg
+ */
+static void rk3x_i2c_prepare_read(struct rk3x_i2c *i2c)
+{
+	unsigned int len = i2c->msg->len - i2c->processed;
+	u32 con;
+
+	con = i2c_readl(i2c, REG_CON);
+
+	/* the hw can read up to 32 bytes at a time. If we need more than one
+	 * chunk, send an ACK after the last byte of the current chunk. */
+	if (unlikely(len > 32)) {
+		len = 32;
+		con &= ~REG_CON_LASTACK;
+	} else
+		con |= REG_CON_LASTACK;
+
+	/* make sure we are in plain RX mode if we read a second chunk */
+	if (i2c->processed != 0) {
+		con &= ~REG_CON_MOD_MASK;
+		con |= REG_CON_MOD(REG_CON_MOD_RX);
+	}
+
+	i2c_writel(i2c, con, REG_CON);
+	i2c_writel(i2c, len, REG_MRXCNT);
+}
+
+/**
+ * Fill the transmit buffer with data from i2c->msg
+ */
+static void rk3x_i2c_fill_transmit_buf(struct rk3x_i2c *i2c)
+{
+	unsigned int i, j;
+	u32 cnt = 0;
+	u32 val;
+	u8 byte;
+
+	for (i = 0; i < 8; ++i) {
+		val = 0;
+		for (j = 0; j < 4; ++j) {
+			if (i2c->processed == i2c->msg->len)
+				break;
+
+			if (i2c->processed == 0 && cnt == 0)
+				byte = (i2c->addr & 0x7f) << 1;
+			else
+				byte = i2c->msg->buf[i2c->processed++];
+
+			val |= byte << (j*8);
+			cnt++;
+		}
+
+		i2c_writel(i2c, val, TXBUFFER_BASE + 4*i);
+
+		if (i2c->processed == i2c->msg->len)
+			break;
+	}
+
+	i2c_writel(i2c, cnt, REG_MTXCNT);
+}
+
+
+/* IRQ handlers for individual states */
+
+static void rk3x_i2c_handle_start(struct rk3x_i2c *i2c, unsigned int ipd)
+{
+	if (!(ipd & REG_INT_START)) {
+		rk3x_i2c_stop(i2c, -ENXIO);
+		dev_warn(i2c->dev, "unexpected irq in START: 0x%x\n", ipd);
+		rk3x_i2c_clean_ipd(i2c);
+		return;
+	}
+
+	/* ack interrupt */
+	i2c_writel(i2c, REG_INT_START, REG_IPD);
+
+	/* disable start bit */
+	i2c_writel(i2c, i2c_readl(i2c, REG_CON) & ~REG_CON_START, REG_CON);
+
+	/* enable appropriate interrupts and transition */
+	if (i2c->mode == REG_CON_MOD_TX) {
+		i2c_writel(i2c, REG_INT_MBTF | REG_INT_NAKRCV, REG_IEN);
+		i2c->state = STATE_WRITE;
+		rk3x_i2c_fill_transmit_buf(i2c);
+	} else {
+		/* in any other case, we are going to be reading. */
+		i2c_writel(i2c, REG_INT_MBRF | REG_INT_NAKRCV, REG_IEN);
+		i2c->state = STATE_READ;
+		rk3x_i2c_prepare_read(i2c);
+	}
+}
+
+static void rk3x_i2c_handle_write(struct rk3x_i2c *i2c, unsigned int ipd)
+{
+	if (!(ipd & REG_INT_MBTF)) {
+		rk3x_i2c_stop(i2c, -ENXIO);
+		dev_err(i2c->dev, "unexpected irq in WRITE: 0x%x\n", ipd);
+		rk3x_i2c_clean_ipd(i2c);
+		return;
+	}
+
+	/* ack interrupt */
+	i2c_writel(i2c, REG_INT_MBTF, REG_IPD);
+
+	/* are we finished? */
+	if (i2c->processed == i2c->msg->len)
+		rk3x_i2c_stop(i2c, i2c->error);
+	else
+		rk3x_i2c_fill_transmit_buf(i2c);
+}
+
+static void rk3x_i2c_handle_read(struct rk3x_i2c *i2c, unsigned int ipd)
+{
+	unsigned int i;
+	unsigned int len = i2c->msg->len - i2c->processed;
+	unsigned int val;
+	u8 byte;
+
+	/* we only care for MBRF here. */
+	if (!(ipd & REG_INT_MBRF))
+		return;
+
+	/* ack interrupt */
+	i2c_writel(i2c, REG_INT_MBRF, REG_IPD);
+
+	/* read the data from receive buffer */
+	for (i = 0; i < len; ++i) {
+		if (i%4 == 0)
+			val = i2c_readl(i2c, RXBUFFER_BASE + (i/4)*4);
+
+		byte = (val >> ((i%4) * 8)) & 0xff;
+		i2c->msg->buf[i2c->processed++] = byte;
+	}
+
+	/* are we finished? */
+	if (i2c->processed == i2c->msg->len)
+		rk3x_i2c_stop(i2c, i2c->error);
+	else
+		rk3x_i2c_prepare_read(i2c);
+}
+
+static void rk3x_i2c_handle_stop(struct rk3x_i2c *i2c, unsigned int ipd)
+{
+	unsigned int con;
+
+	if (!(ipd & REG_INT_STOP)) {
+		rk3x_i2c_stop(i2c, -ENXIO);
+		dev_err(i2c->dev, "unexpected irq in STOP: 0x%x\n", ipd);
+		rk3x_i2c_clean_ipd(i2c);
+		return;
+	}
+
+	/* ack interrupt */
+	i2c_writel(i2c, REG_INT_STOP, REG_IPD);
+
+	/* disable STOP bit */
+	con = i2c_readl(i2c, REG_CON);
+	con &= ~REG_CON_STOP;
+	i2c_writel(i2c, con, REG_CON);
+
+	i2c->busy = 0;
+	i2c->state = STATE_IDLE;
+
+	/* signal rk3x_i2c_xfer that we are finished */
+	wake_up(&i2c->wait);
+}
+
+static irqreturn_t rk3x_i2c_irq(int irqno, void *dev_id)
+{
+	struct rk3x_i2c *i2c = dev_id;
+	unsigned int ipd;
+
+	spin_lock(&i2c->lock);
+
+	ipd = i2c_readl(i2c, REG_IPD);
+	if (i2c->state == STATE_IDLE) {
+		dev_warn(i2c->dev, "irq in STATE_IDLE, ipd = 0x%x\n", ipd);
+		rk3x_i2c_clean_ipd(i2c);
+		goto out;
+	}
+
+	dev_dbg(i2c->dev, "IRQ: state %d, ipd: %x\n", i2c->state, ipd);
+
+	/* Clean interrupt bits we don't care about */
+	ipd &= ~(REG_INT_BRF | REG_INT_BTF);
+
+	if (ipd & REG_INT_NAKRCV) {
+		/* We got a NACK in the last operation. Depending on whether
+		 * IGNORE_NAK is set, we have to stop the operation and report
+		 * an error. */
+		i2c_writel(i2c, REG_INT_NAKRCV, REG_IPD);
+
+		ipd &= ~REG_INT_NAKRCV;
+
+		if (!(i2c->msg->flags & I2C_M_IGNORE_NAK))
+			rk3x_i2c_stop(i2c, -EAGAIN);
+	}
+
+	/* is there anything left to handle? */
+	if (unlikely(ipd == 0))
+		goto out;
+
+	switch (i2c->state) {
+	case STATE_START:
+		rk3x_i2c_handle_start(i2c, ipd);
+		break;
+	case STATE_WRITE:
+		rk3x_i2c_handle_write(i2c, ipd);
+		break;
+	case STATE_READ:
+		rk3x_i2c_handle_read(i2c, ipd);
+		break;
+	case STATE_STOP:
+		rk3x_i2c_handle_stop(i2c, ipd);
+		break;
+	case STATE_IDLE:
+		break;
+	}
+
+out:
+	spin_unlock(&i2c->lock);
+	return IRQ_HANDLED;
+}
+
+static void rk3x_i2c_set_scl_rate(struct rk3x_i2c *i2c, unsigned long scl_rate)
+{
+	unsigned long i2c_rate = clk_get_rate(i2c->clk);
+	unsigned int div;
+
+	/* SCL rate = (clk rate) / (8 * DIV) */
+	div = DIV_ROUND_UP(i2c_rate, scl_rate * 8);
+
+	/* The lower and upper half of the CLKDIV reg describe the length of
+	 * SCL low & high periods. */
+	div = DIV_ROUND_UP(div, 2);
+
+	i2c_writel(i2c, (div << 16) | (div & 0xffff), REG_CLKDIV);
+}
+
+/**
+ * Setup I2C registers for an I2C operation specified by msgs, num.
+ *
+ * Must be called with i2c->lock held.
+ *
+ * @msgs: I2C msgs to process
+ * @num: Number of msgs
+ *
+ * returns: Number of I2C msgs processed or negative in case of error
+ */
+static int rk3x_i2c_setup(struct rk3x_i2c *i2c, struct i2c_msg *msgs, int num)
+{
+	u32 addr = (msgs[0].addr & 0x7f) << 1;
+	int ret = 0;
+
+	/*
+	 * The I2C adapter can issue a small (len < 4) write packet before
+	 * reading. This speeds up SMBus-style register reads.
+	 * The MRXADDR/MRXRADDR hold the slave address and the slave register
+	 * address in this case.
+	 */
+
+	if (num >= 2 && msgs[0].len < 4
+	    && !(msgs[0].flags & I2C_M_RD)
+	    && (msgs[1].flags & I2C_M_RD)) {
+		u32 reg_addr = 0;
+
+		dev_dbg(i2c->dev, "Combined write/read from addr 0x%x\n",
+			addr >> 1);
+
+		if (msgs[0].len == 0)
+			return -EINVAL;
+
+		/* Fill MRXRADDR with the register address(es) */
+		reg_addr = msgs[0].buf[0];
+		reg_addr |= REG_MRXADDR_LOW;
+
+		if (msgs[0].len >= 2) {
+			reg_addr |= msgs[0].buf[1] << 8;
+			reg_addr |= REG_MRXADDR_MID;
+
+			if (msgs[0].len >= 3) {
+				reg_addr |= msgs[0].buf[2] << 16;
+				reg_addr |= REG_MRXADDR_HIGH;
+			}
+		}
+
+		/* msgs[0] is handled by hw. */
+		i2c->msg = &msgs[1];
+
+		i2c->mode = REG_CON_MOD_REGISTER_TX;
+
+		i2c_writel(i2c, addr | REG_MRXADDR_LOW, REG_MRXADDR);
+		i2c_writel(i2c, reg_addr, REG_MRXRADDR);
+
+		ret = 2;
+	} else {
+		/* We'll have to do it the boring way and process the msgs
+		 * one-by-one. */
+
+		if (msgs[0].flags & I2C_M_RD) {
+			addr |= 1; /* set read bit */
+
+			/* We have to transmit the slave addr first. Use
+			 * MOD_REGISTER_TX for that purpose. */
+			i2c->mode = REG_CON_MOD_REGISTER_TX;
+			i2c_writel(i2c, addr | REG_MRXADDR_LOW, REG_MRXADDR);
+			i2c_writel(i2c, 0, REG_MRXRADDR);
+		} else {
+			i2c->mode = REG_CON_MOD_TX;
+		}
+
+		i2c->msg = &msgs[0];
+
+		ret = 1;
+	}
+
+	i2c->addr = msgs[0].addr;
+	i2c->busy = true;
+	i2c->state = STATE_START;
+	i2c->processed = 0;
+	i2c->error = 0;
+
+	rk3x_i2c_clean_ipd(i2c);
+
+	return ret;
+}
+
+static int rk3x_i2c_xfer(struct i2c_adapter *adap,
+			 struct i2c_msg *msgs, int num)
+{
+	struct rk3x_i2c *i2c = (struct rk3x_i2c *)adap->algo_data;
+	unsigned long timeout, flags;
+	int ret = 0;
+	int i;
+
+	spin_lock_irqsave(&i2c->lock, flags);
+
+	clk_enable(i2c->clk);
+
+	/* The clock rate might have changed, so setup the divider again */
+	rk3x_i2c_set_scl_rate(i2c, i2c->scl_frequency);
+
+	/* Process msgs. We can handle more than one message at once (see
+	 * rk3x_i2c_setup()). */
+	for (i = 0; i < num; i += ret) {
+		ret = rk3x_i2c_setup(i2c, msgs + i, num);
+
+		if (ret < 0) {
+			dev_err(i2c->dev, "rk3x_i2c_setup() failed\n");
+			break;
+		}
+
+		spin_unlock_irqrestore(&i2c->lock, flags);
+
+		rk3x_i2c_start(i2c);
+
+		timeout = wait_event_timeout(i2c->wait, !i2c->busy,
+					     msecs_to_jiffies(WAIT_TIMEOUT));
+
+		spin_lock_irqsave(&i2c->lock, flags);
+
+		if (timeout == 0) {
+			dev_err(i2c->dev, "timeout, ipd: 0x%08X",
+				i2c_readl(i2c, REG_IPD));
+
+			/* Force a STOP condition without interrupt */
+			i2c_writel(i2c, 0, REG_IEN);
+			i2c_writel(i2c, REG_CON_EN | REG_CON_STOP, REG_CON);
+
+			i2c->state = STATE_IDLE;
+
+			ret = -ETIMEDOUT;
+			break;
+		}
+
+		if (i2c->error) {
+			ret = i2c->error;
+			break;
+		}
+	}
+
+	clk_disable(i2c->clk);
+	spin_unlock_irqrestore(&i2c->lock, flags);
+
+	return ret;
+}
+
+static u32 rk3x_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
+}
+
+static const struct i2c_algorithm rk3x_i2c_algorithm = {
+	.master_xfer		= rk3x_i2c_xfer,
+	.functionality		= rk3x_i2c_func,
+};
+
+static const struct of_device_id rk3x_i2c_match[];
+
+static int rk3x_i2c_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	const struct of_device_id *match;
+	struct rk3x_i2c *i2c;
+	struct resource *mem;
+	int ret = 0;
+	u32 value;
+
+	if (!pdev->dev.of_node) {
+		dev_err(&pdev->dev, "rk3x-i2c needs a devicetree node\n");
+		return -EINVAL;
+	}
+
+	i2c = devm_kzalloc(&pdev->dev, sizeof(struct rk3x_i2c), GFP_KERNEL);
+	if (!i2c)
+		return -ENOMEM;
+
+	match = of_match_node(rk3x_i2c_match, np);
+	i2c->soc_data = (struct rk3x_i2c_soc_data *)match->data;
+
+	if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
+				 &i2c->scl_frequency)) {
+		i2c->scl_frequency = 100 * 1000;
+		dev_info(&pdev->dev, "using default SCL frequency: 100kHz\n");
+	}
+
+	strlcpy(i2c->adap.name, "rk3x-i2c", sizeof(i2c->adap.name));
+	i2c->adap.owner = THIS_MODULE;
+	i2c->adap.algo = &rk3x_i2c_algorithm;
+	i2c->adap.retries = 3;
+	i2c->adap.dev.of_node = np;
+	i2c->adap.algo_data = i2c;
+	i2c->adap.dev.parent = &pdev->dev;
+
+	i2c->dev = &pdev->dev;
+
+	spin_lock_init(&i2c->lock);
+	init_waitqueue_head(&i2c->wait);
+
+	i2c->clk = devm_clk_get(&pdev->dev, 0);
+	if (IS_ERR(i2c->clk)) {
+		dev_err(&pdev->dev, "cannot get clock\n");
+		return PTR_ERR(i2c->clk);
+	}
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	i2c->regs = devm_ioremap_resource(&pdev->dev, mem);
+	if (IS_ERR(i2c->regs))
+		return PTR_ERR(i2c->regs);
+
+	/* Switch to new interface if the SoC also offers the old one.
+	 * The control bit is located in the GRF register space. */
+	if (i2c->soc_data->grf_offset >= 0) {
+		ret = of_property_read_u32(pdev->dev.of_node,
+				    "rockchip,bus-index", &i2c->bus_index);
+		if (ret < 0) {
+			dev_err(&pdev->dev,
+				"rk3x-i2c needs 'rockchip,bus-index' prop\n");
+			return ret;
+		}
+
+		i2c->grf = syscon_regmap_lookup_by_phandle(np, "rockchip,grf");
+		if (IS_ERR(i2c->grf)) {
+			dev_err(&pdev->dev,
+				"rk3x-i2c needs 'rockchip,grf' property\n");
+			return PTR_ERR(i2c->grf);
+		}
+
+		/* 27+i: write mask, 11+i: value */
+		value = BIT(27 + i2c->bus_index) | BIT(11 + i2c->bus_index);
+
+		ret = regmap_write(i2c->grf, i2c->soc_data->grf_offset, value);
+		if (ret != 0) {
+			dev_err(i2c->dev, "Could not write to GRF: %d\n", ret);
+			return ret;
+		}
+	}
+
+	/* IRQ setup */
+	i2c->irq = platform_get_irq(pdev, 0);
+	if (i2c->irq < 0) {
+		dev_err(&pdev->dev, "cannot find rk3x IRQ\n");
+		return i2c->irq;
+	}
+
+	ret = devm_request_irq(&pdev->dev, i2c->irq, rk3x_i2c_irq,
+			       0, dev_name(&pdev->dev), i2c);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "cannot request IRQ\n");
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, i2c);
+
+	ret = clk_prepare(i2c->clk);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Could not prepare clock\n");
+		return ret;
+	}
+
+	ret = i2c_add_adapter(&i2c->adap);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Could not register adapter\n");
+		goto err_clk;
+	}
+
+	dev_info(&pdev->dev, "Initialized RK3xxx I2C bus at 0x%08x\n",
+		 (unsigned int)i2c->regs);
+
+	return 0;
+
+err_clk:
+	clk_unprepare(i2c->clk);
+	return ret;
+}
+
+static int rk3x_i2c_remove(struct platform_device *pdev)
+{
+	struct rk3x_i2c *i2c = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&i2c->adap);
+	clk_unprepare(i2c->clk);
+
+	return 0;
+}
+
+static struct rk3x_i2c_soc_data soc_data[3] = {
+	{ .grf_offset = 0x154 }, /* rk3066 */
+	{ .grf_offset = 0x0a4 }, /* rk3188 */
+	{ .grf_offset = -1 },    /* no I2C switching needed */
+};
+
+static const struct of_device_id rk3x_i2c_match[] = {
+	{ .compatible = "rockchip,rk3066-i2c", .data = (void *)&soc_data[0] },
+	{ .compatible = "rockchip,rk3188-i2c", .data = (void *)&soc_data[1] },
+	{ .compatible = "rockchip,rk3288-i2c", .data = (void *)&soc_data[2] },
+};
+
+static struct platform_driver rk3x_i2c_driver = {
+	.probe   = rk3x_i2c_probe,
+	.remove  = rk3x_i2c_remove,
+	.driver  = {
+		.owner = THIS_MODULE,
+		.name  = "rk3x-i2c",
+		.of_match_table = rk3x_i2c_match,
+	},
+};
+
+module_platform_driver(rk3x_i2c_driver);
+
+MODULE_DESCRIPTION("Rockchip RK3xxx I2C Bus driver");
+MODULE_AUTHOR("Max Schwarz <max.schwarz@...ine.de>");
+MODULE_LICENSE("GPL v2");
-- 
1.8.3.2


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