Add the rt linux 4.1.3-rt3 as base

Import the rt linux 4.1.3-rt3 as OPNFV kvm base.

It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:

commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date:   Sat Jul 25 12:13:34 2015 +0200

    Prepare v4.1.3-rt3

    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.

Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>

1 files changed, 1043 insertions, 0 deletions

diff --git a/kernel/drivers/i2c/busses/i2c-rk3x.c b/kernel/drivers/i2c/busses/i2c-rk3x.c
new file mode 100644
index 000000000..019d5426f
--- /dev/null
+++ b/kernel/drivers/i2c/busses/i2c-rk3x.c
@@ -0,0 +1,1043 @@
+/*
+ * Driver for I2C adapter in Rockchip RK3xxx SoC
+ *
+ * Max Schwarz <max.schwarz@online.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/interrupt.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>
+#include <linux/math64.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        BIT(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  (BIT(1) | BIT(2))
+#define REG_CON_START     BIT(3)
+#define REG_CON_STOP      BIT(4)
+#define REG_CON_LASTACK   BIT(5) /* 1: send NACK after last received byte */
+#define REG_CON_ACTACK    BIT(6) /* 1: stop if NACK is received */
+
+/* REG_MRXADDR bits */
+#define REG_MRXADDR_VALID(x) BIT(24 + (x)) /* [x*8+7:x*8] of MRX[R]ADDR valid */
+
+/* REG_IEN/REG_IPD bits */
+#define REG_INT_BTF       BIT(0) /* a byte was transmitted */
+#define REG_INT_BRF       BIT(1) /* a byte was received */
+#define REG_INT_MBTF      BIT(2) /* master data transmit finished */
+#define REG_INT_MBRF      BIT(3) /* master data receive finished */
+#define REG_INT_START     BIT(4) /* START condition generated */
+#define REG_INT_STOP      BIT(5) /* STOP condition generated */
+#define REG_INT_NAKRCV    BIT(6) /* NACK received */
+#define REG_INT_ALL       0x7f
+
+/* Constants */
+#define WAIT_TIMEOUT      200 /* ms */
+#define DEFAULT_SCL_RATE  (100 * 1000) /* Hz */
+
+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 clk *clk;
+	struct notifier_block clk_rate_nb;
+
+	/* Settings */
+	unsigned int scl_frequency;
+	unsigned int scl_rise_ns;
+	unsigned int scl_fall_ns;
+	unsigned int sda_fall_ns;
+
+	/* Synchronization & notification */
+	spinlock_t lock;
+	wait_queue_head_t wait;
+	bool busy;
+
+	/* Current message */
+	struct i2c_msg *msg;
+	u8 addr;
+	unsigned int mode;
+	bool is_last_msg;
+
+	/* 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 = NULL;
+	i2c->error = error;
+
+	if (i2c->is_last_msg) {
+		/* 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);
+	} else {
+		/* Signal rk3x_i2c_xfer to start the next message. */
+		i2c->busy = false;
+		i2c->state = STATE_IDLE;
+
+		/*
+		 * The HW is actually not capable of REPEATED START. But we can
+		 * get the intended effect by resetting its internal state
+		 * and issuing an ordinary START.
+		 */
+		i2c_writel(i2c, 0, REG_CON);
+
+		/* signal that we are finished with the current msg */
+		wake_up(&i2c->wait);
+	}
+}
+
+/**
+ * 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 (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) && (cnt != 0))
+				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, -EIO);
+		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, -EIO);
+		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;
+	u32 uninitialized_var(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);
+
+	/* Can only handle a maximum of 32 bytes at a time */
+	if (len > 32)
+		len = 32;
+
+	/* 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, -EIO);
+		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 = false;
+	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, -ENXIO);
+	}
+
+	/* is there anything left to handle? */
+	if ((ipd & REG_INT_ALL) == 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;
+}
+
+/**
+ * Calculate divider values for desired SCL frequency
+ *
+ * @clk_rate: I2C input clock rate
+ * @scl_rate: Desired SCL rate
+ * @scl_rise_ns: How many ns it takes for SCL to rise.
+ * @scl_fall_ns: How many ns it takes for SCL to fall.
+ * @sda_fall_ns: How many ns it takes for SDA to fall.
+ * @div_low: Divider output for low
+ * @div_high: Divider output for high
+ *
+ * Returns: 0 on success, -EINVAL if the goal SCL rate is too slow. In that case
+ * a best-effort divider value is returned in divs. If the target rate is
+ * too high, we silently use the highest possible rate.
+ */
+static int rk3x_i2c_calc_divs(unsigned long clk_rate, unsigned long scl_rate,
+			      unsigned long scl_rise_ns,
+			      unsigned long scl_fall_ns,
+			      unsigned long sda_fall_ns,
+			      unsigned long *div_low, unsigned long *div_high)
+{
+	unsigned long spec_min_low_ns, spec_min_high_ns;
+	unsigned long spec_setup_start, spec_max_data_hold_ns;
+	unsigned long data_hold_buffer_ns;
+
+	unsigned long min_low_ns, min_high_ns;
+	unsigned long max_low_ns, min_total_ns;
+
+	unsigned long clk_rate_khz, scl_rate_khz;
+
+	unsigned long min_low_div, min_high_div;
+	unsigned long max_low_div;
+
+	unsigned long min_div_for_hold, min_total_div;
+	unsigned long extra_div, extra_low_div, ideal_low_div;
+
+	int ret = 0;
+
+	/* Only support standard-mode and fast-mode */
+	if (WARN_ON(scl_rate > 400000))
+		scl_rate = 400000;
+
+	/* prevent scl_rate_khz from becoming 0 */
+	if (WARN_ON(scl_rate < 1000))
+		scl_rate = 1000;
+
+	/*
+	 * min_low_ns:  The minimum number of ns we need to hold low to
+	 *		meet I2C specification, should include fall time.
+	 * min_high_ns: The minimum number of ns we need to hold high to
+	 *		meet I2C specification, should include rise time.
+	 * max_low_ns:  The maximum number of ns we can hold low to meet
+	 *		I2C specification.
+	 *
+	 * Note: max_low_ns should be (maximum data hold time * 2 - buffer)
+	 *	 This is because the i2c host on Rockchip holds the data line
+	 *	 for half the low time.
+	 */
+	if (scl_rate <= 100000) {
+		/* Standard-mode */
+		spec_min_low_ns = 4700;
+		spec_setup_start = 4700;
+		spec_min_high_ns = 4000;
+		spec_max_data_hold_ns = 3450;
+		data_hold_buffer_ns = 50;
+	} else {
+		/* Fast-mode */
+		spec_min_low_ns = 1300;
+		spec_setup_start = 600;
+		spec_min_high_ns = 600;
+		spec_max_data_hold_ns = 900;
+		data_hold_buffer_ns = 50;
+	}
+	min_high_ns = scl_rise_ns + spec_min_high_ns;
+
+	/*
+	 * Timings for repeated start:
+	 * - controller appears to drop SDA at .875x (7/8) programmed clk high.
+	 * - controller appears to keep SCL high for 2x programmed clk high.
+	 *
+	 * We need to account for those rules in picking our "high" time so
+	 * we meet tSU;STA and tHD;STA times.
+	 */
+	min_high_ns = max(min_high_ns,
+		DIV_ROUND_UP((scl_rise_ns + spec_setup_start) * 1000, 875));
+	min_high_ns = max(min_high_ns,
+		DIV_ROUND_UP((scl_rise_ns + spec_setup_start +
+			      sda_fall_ns + spec_min_high_ns), 2));
+
+	min_low_ns = scl_fall_ns + spec_min_low_ns;
+	max_low_ns = spec_max_data_hold_ns * 2 - data_hold_buffer_ns;
+	min_total_ns = min_low_ns + min_high_ns;
+
+	/* Adjust to avoid overflow */
+	clk_rate_khz = DIV_ROUND_UP(clk_rate, 1000);
+	scl_rate_khz = scl_rate / 1000;
+
+	/*
+	 * We need the total div to be >= this number
+	 * so we don't clock too fast.
+	 */
+	min_total_div = DIV_ROUND_UP(clk_rate_khz, scl_rate_khz * 8);
+
+	/* These are the min dividers needed for min hold times. */
+	min_low_div = DIV_ROUND_UP(clk_rate_khz * min_low_ns, 8 * 1000000);
+	min_high_div = DIV_ROUND_UP(clk_rate_khz * min_high_ns, 8 * 1000000);
+	min_div_for_hold = (min_low_div + min_high_div);
+
+	/*
+	 * This is the maximum divider so we don't go over the maximum.
+	 * We don't round up here (we round down) since this is a maximum.
+	 */
+	max_low_div = clk_rate_khz * max_low_ns / (8 * 1000000);
+
+	if (min_low_div > max_low_div) {
+		WARN_ONCE(true,
+			  "Conflicting, min_low_div %lu, max_low_div %lu\n",
+			  min_low_div, max_low_div);
+		max_low_div = min_low_div;
+	}
+
+	if (min_div_for_hold > min_total_div) {
+		/*
+		 * Time needed to meet hold requirements is important.
+		 * Just use that.
+		 */
+		*div_low = min_low_div;
+		*div_high = min_high_div;
+	} else {
+		/*
+		 * We've got to distribute some time among the low and high
+		 * so we don't run too fast.
+		 */
+		extra_div = min_total_div - min_div_for_hold;
+
+		/*
+		 * We'll try to split things up perfectly evenly,
+		 * biasing slightly towards having a higher div
+		 * for low (spend more time low).
+		 */
+		ideal_low_div = DIV_ROUND_UP(clk_rate_khz * min_low_ns,
+					     scl_rate_khz * 8 * min_total_ns);
+
+		/* Don't allow it to go over the maximum */
+		if (ideal_low_div > max_low_div)
+			ideal_low_div = max_low_div;
+
+		/*
+		 * Handle when the ideal low div is going to take up
+		 * more than we have.
+		 */
+		if (ideal_low_div > min_low_div + extra_div)
+			ideal_low_div = min_low_div + extra_div;
+
+		/* Give low the "ideal" and give high whatever extra is left */
+		extra_low_div = ideal_low_div - min_low_div;
+		*div_low = ideal_low_div;
+		*div_high = min_high_div + (extra_div - extra_low_div);
+	}
+
+	/*
+	 * Adjust to the fact that the hardware has an implicit "+1".
+	 * NOTE: Above calculations always produce div_low > 0 and div_high > 0.
+	 */
+	*div_low = *div_low - 1;
+	*div_high = *div_high - 1;
+
+	/* Maximum divider supported by hw is 0xffff */
+	if (*div_low > 0xffff) {
+		*div_low = 0xffff;
+		ret = -EINVAL;
+	}
+
+	if (*div_high > 0xffff) {
+		*div_high = 0xffff;
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+static void rk3x_i2c_adapt_div(struct rk3x_i2c *i2c, unsigned long clk_rate)
+{
+	unsigned long div_low, div_high;
+	u64 t_low_ns, t_high_ns;
+	int ret;
+
+	ret = rk3x_i2c_calc_divs(clk_rate, i2c->scl_frequency, i2c->scl_rise_ns,
+				 i2c->scl_fall_ns, i2c->sda_fall_ns,
+				 &div_low, &div_high);
+	WARN_ONCE(ret != 0, "Could not reach SCL freq %u", i2c->scl_frequency);
+
+	clk_enable(i2c->clk);
+	i2c_writel(i2c, (div_high << 16) | (div_low & 0xffff), REG_CLKDIV);
+	clk_disable(i2c->clk);
+
+	t_low_ns = div_u64(((u64)div_low + 1) * 8 * 1000000000, clk_rate);
+	t_high_ns = div_u64(((u64)div_high + 1) * 8 * 1000000000, clk_rate);
+	dev_dbg(i2c->dev,
+		"CLK %lukhz, Req %uns, Act low %lluns high %lluns\n",
+		clk_rate / 1000,
+		1000000000 / i2c->scl_frequency,
+		t_low_ns, t_high_ns);
+}
+
+/**
+ * rk3x_i2c_clk_notifier_cb - Clock rate change callback
+ * @nb:		Pointer to notifier block
+ * @event:	Notification reason
+ * @data:	Pointer to notification data object
+ *
+ * The callback checks whether a valid bus frequency can be generated after the
+ * change. If so, the change is acknowledged, otherwise the change is aborted.
+ * New dividers are written to the HW in the pre- or post change notification
+ * depending on the scaling direction.
+ *
+ * Code adapted from i2c-cadence.c.
+ *
+ * Return:	NOTIFY_STOP if the rate change should be aborted, NOTIFY_OK
+ *		to acknowedge the change, NOTIFY_DONE if the notification is
+ *		considered irrelevant.
+ */
+static int rk3x_i2c_clk_notifier_cb(struct notifier_block *nb, unsigned long
+				    event, void *data)
+{
+	struct clk_notifier_data *ndata = data;
+	struct rk3x_i2c *i2c = container_of(nb, struct rk3x_i2c, clk_rate_nb);
+	unsigned long div_low, div_high;
+
+	switch (event) {
+	case PRE_RATE_CHANGE:
+		if (rk3x_i2c_calc_divs(ndata->new_rate, i2c->scl_frequency,
+				       i2c->scl_rise_ns, i2c->scl_fall_ns,
+				       i2c->sda_fall_ns,
+				       &div_low, &div_high) != 0)
+			return NOTIFY_STOP;
+
+		/* scale up */
+		if (ndata->new_rate > ndata->old_rate)
+			rk3x_i2c_adapt_div(i2c, ndata->new_rate);
+
+		return NOTIFY_OK;
+	case POST_RATE_CHANGE:
+		/* scale down */
+		if (ndata->new_rate < ndata->old_rate)
+			rk3x_i2c_adapt_div(i2c, ndata->new_rate);
+		return NOTIFY_OK;
+	case ABORT_RATE_CHANGE:
+		/* scale up */
+		if (ndata->new_rate > ndata->old_rate)
+			rk3x_i2c_adapt_div(i2c, ndata->old_rate);
+		return NOTIFY_OK;
+	default:
+		return NOTIFY_DONE;
+	}
+}
+
+/**
+ * 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;
+		int i;
+
+		dev_dbg(i2c->dev, "Combined write/read from addr 0x%x\n",
+			addr >> 1);
+
+		/* Fill MRXRADDR with the register address(es) */
+		for (i = 0; i < msgs[0].len; ++i) {
+			reg_addr |= msgs[0].buf[i] << (i * 8);
+			reg_addr |= REG_MRXADDR_VALID(i);
+		}
+
+		/* msgs[0] is handled by hw. */
+		i2c->msg = &msgs[1];
+
+		i2c->mode = REG_CON_MOD_REGISTER_TX;
+
+		i2c_writel(i2c, addr | REG_MRXADDR_VALID(0), 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_VALID(0),
+				   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);
+
+	i2c->is_last_msg = false;
+
+	/*
+	 * 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 - i);
+
+		if (ret < 0) {
+			dev_err(i2c->dev, "rk3x_i2c_setup() failed\n");
+			break;
+		}
+
+		if (i + ret >= num)
+			i2c->is_last_msg = true;
+
+		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%02x, state: %d\n",
+				i2c_readl(i2c, REG_IPD), i2c->state);
+
+			/* 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 < 0 ? ret : num;
+}
+
+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 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 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;
+	int bus_nr;
+	u32 value;
+	int irq;
+	unsigned long clk_rate;
+
+	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)) {
+		dev_info(&pdev->dev, "using default SCL frequency: %d\n",
+			 DEFAULT_SCL_RATE);
+		i2c->scl_frequency = DEFAULT_SCL_RATE;
+	}
+
+	if (i2c->scl_frequency == 0 || i2c->scl_frequency > 400 * 1000) {
+		dev_warn(&pdev->dev, "invalid SCL frequency specified.\n");
+		dev_warn(&pdev->dev, "using default SCL frequency: %d\n",
+			 DEFAULT_SCL_RATE);
+		i2c->scl_frequency = DEFAULT_SCL_RATE;
+	}
+
+	/*
+	 * Read rise and fall time from device tree. If not available use
+	 * the default maximum timing from the specification.
+	 */
+	if (of_property_read_u32(pdev->dev.of_node, "i2c-scl-rising-time-ns",
+				 &i2c->scl_rise_ns)) {
+		if (i2c->scl_frequency <= 100000)
+			i2c->scl_rise_ns = 1000;
+		else
+			i2c->scl_rise_ns = 300;
+	}
+	if (of_property_read_u32(pdev->dev.of_node, "i2c-scl-falling-time-ns",
+				 &i2c->scl_fall_ns))
+		i2c->scl_fall_ns = 300;
+	if (of_property_read_u32(pdev->dev.of_node, "i2c-sda-falling-time-ns",
+				 &i2c->scl_fall_ns))
+		i2c->sda_fall_ns = i2c->scl_fall_ns;
+
+	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, NULL);
+	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);
+
+	/* Try to set the I2C adapter number from dt */
+	bus_nr = of_alias_get_id(np, "i2c");
+
+	/*
+	 * 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) {
+		struct regmap *grf;
+
+		grf = syscon_regmap_lookup_by_phandle(np, "rockchip,grf");
+		if (IS_ERR(grf)) {
+			dev_err(&pdev->dev,
+				"rk3x-i2c needs 'rockchip,grf' property\n");
+			return PTR_ERR(grf);
+		}
+
+		if (bus_nr < 0) {
+			dev_err(&pdev->dev, "rk3x-i2c needs i2cX alias");
+			return -EINVAL;
+		}
+
+		/* 27+i: write mask, 11+i: value */
+		value = BIT(27 + bus_nr) | BIT(11 + bus_nr);
+
+		ret = regmap_write(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 */
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "cannot find rk3x IRQ\n");
+		return irq;
+	}
+
+	ret = devm_request_irq(&pdev->dev, 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;
+	}
+
+	i2c->clk_rate_nb.notifier_call = rk3x_i2c_clk_notifier_cb;
+	ret = clk_notifier_register(i2c->clk, &i2c->clk_rate_nb);
+	if (ret != 0) {
+		dev_err(&pdev->dev, "Unable to register clock notifier\n");
+		goto err_clk;
+	}
+
+	clk_rate = clk_get_rate(i2c->clk);
+	rk3x_i2c_adapt_div(i2c, clk_rate);
+
+	ret = i2c_add_adapter(&i2c->adap);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Could not register adapter\n");
+		goto err_clk_notifier;
+	}
+
+	dev_info(&pdev->dev, "Initialized RK3xxx I2C bus at %p\n", i2c->regs);
+
+	return 0;
+
+err_clk_notifier:
+	clk_notifier_unregister(i2c->clk, &i2c->clk_rate_nb);
+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_notifier_unregister(i2c->clk, &i2c->clk_rate_nb);
+	clk_unprepare(i2c->clk);
+
+	return 0;
+}
+
+static struct platform_driver rk3x_i2c_driver = {
+	.probe   = rk3x_i2c_probe,
+	.remove  = rk3x_i2c_remove,
+	.driver  = {
+		.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@online.de>");
+MODULE_LICENSE("GPL v2");