Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1214 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
new file mode 100644
index 000000000..cef82b205
--- /dev/null
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -0,0 +1,1214 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for the Renesas R-Car I2C unit
+ *
+ * Copyright (C) 2014-19 Wolfram Sang <wsa@sang-engineering.com>
+ * Copyright (C) 2011-2019 Renesas Electronics Corporation
+ *
+ * Copyright (C) 2012-14 Renesas Solutions Corp.
+ * Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
+ *
+ * This file is based on the drivers/i2c/busses/i2c-sh7760.c
+ * (c) 2005-2008 MSC Vertriebsges.m.b.H, Manuel Lauss <mlau@msc-ge.com>
+ */
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/i2c.h>
+#include <linux/i2c-smbus.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/reset.h>
+#include <linux/slab.h>
+
+/* register offsets */
+#define ICSCR	0x00	/* slave ctrl */
+#define ICMCR	0x04	/* master ctrl */
+#define ICSSR	0x08	/* slave status */
+#define ICMSR	0x0C	/* master status */
+#define ICSIER	0x10	/* slave irq enable */
+#define ICMIER	0x14	/* master irq enable */
+#define ICCCR	0x18	/* clock dividers */
+#define ICSAR	0x1C	/* slave address */
+#define ICMAR	0x20	/* master address */
+#define ICRXTX	0x24	/* data port */
+#define ICFBSCR	0x38	/* first bit setup cycle (Gen3) */
+#define ICDMAER	0x3c	/* DMA enable (Gen3) */
+
+/* ICSCR */
+#define SDBS	BIT(3)	/* slave data buffer select */
+#define SIE	BIT(2)	/* slave interface enable */
+#define GCAE	BIT(1)	/* general call address enable */
+#define FNA	BIT(0)	/* forced non acknowledgment */
+
+/* ICMCR */
+#define MDBS	BIT(7)	/* non-fifo mode switch */
+#define FSCL	BIT(6)	/* override SCL pin */
+#define FSDA	BIT(5)	/* override SDA pin */
+#define OBPC	BIT(4)	/* override pins */
+#define MIE	BIT(3)	/* master if enable */
+#define TSBE	BIT(2)
+#define FSB	BIT(1)	/* force stop bit */
+#define ESG	BIT(0)	/* enable start bit gen */
+
+/* ICSSR (also for ICSIER) */
+#define GCAR	BIT(6)	/* general call received */
+#define STM	BIT(5)	/* slave transmit mode */
+#define SSR	BIT(4)	/* stop received */
+#define SDE	BIT(3)	/* slave data empty */
+#define SDT	BIT(2)	/* slave data transmitted */
+#define SDR	BIT(1)	/* slave data received */
+#define SAR	BIT(0)	/* slave addr received */
+
+/* ICMSR (also for ICMIE) */
+#define MNR	BIT(6)	/* nack received */
+#define MAL	BIT(5)	/* arbitration lost */
+#define MST	BIT(4)	/* sent a stop */
+#define MDE	BIT(3)
+#define MDT	BIT(2)
+#define MDR	BIT(1)
+#define MAT	BIT(0)	/* slave addr xfer done */
+
+/* ICDMAER */
+#define RSDMAE	BIT(3)	/* DMA Slave Received Enable */
+#define TSDMAE	BIT(2)	/* DMA Slave Transmitted Enable */
+#define RMDMAE	BIT(1)	/* DMA Master Received Enable */
+#define TMDMAE	BIT(0)	/* DMA Master Transmitted Enable */
+
+/* ICFBSCR */
+#define TCYC17	0x0f		/* 17*Tcyc delay 1st bit between SDA and SCL */
+
+#define RCAR_MIN_DMA_LEN	8
+
+#define RCAR_BUS_PHASE_START	(MDBS | MIE | ESG)
+#define RCAR_BUS_PHASE_DATA	(MDBS | MIE)
+#define RCAR_BUS_PHASE_STOP	(MDBS | MIE | FSB)
+
+#define RCAR_IRQ_SEND	(MNR | MAL | MST | MAT | MDE)
+#define RCAR_IRQ_RECV	(MNR | MAL | MST | MAT | MDR)
+#define RCAR_IRQ_STOP	(MST)
+
+#define ID_LAST_MSG		BIT(0)
+#define ID_REP_AFTER_RD		BIT(1)
+#define ID_DONE			BIT(2)
+#define ID_ARBLOST		BIT(3)
+#define ID_NACK			BIT(4)
+#define ID_EPROTO		BIT(5)
+/* persistent flags */
+#define ID_P_NOT_ATOMIC		BIT(28)
+#define ID_P_HOST_NOTIFY	BIT(29)
+#define ID_P_NO_RXDMA		BIT(30) /* HW forbids RXDMA sometimes */
+#define ID_P_PM_BLOCKED		BIT(31)
+#define ID_P_MASK		GENMASK(31, 28)
+
+enum rcar_i2c_type {
+	I2C_RCAR_GEN1,
+	I2C_RCAR_GEN2,
+	I2C_RCAR_GEN3,
+};
+
+struct rcar_i2c_priv {
+	u32 flags;
+	void __iomem *io;
+	struct i2c_adapter adap;
+	struct i2c_msg *msg;
+	int msgs_left;
+	struct clk *clk;
+
+	wait_queue_head_t wait;
+
+	int pos;
+	u32 icccr;
+	u8 recovery_icmcr;	/* protected by adapter lock */
+	enum rcar_i2c_type devtype;
+	struct i2c_client *slave;
+
+	struct resource *res;
+	struct dma_chan *dma_tx;
+	struct dma_chan *dma_rx;
+	struct scatterlist sg;
+	enum dma_data_direction dma_direction;
+
+	struct reset_control *rstc;
+	int irq;
+
+	struct i2c_client *host_notify_client;
+};
+
+#define rcar_i2c_priv_to_dev(p)		((p)->adap.dev.parent)
+#define rcar_i2c_is_recv(p)		((p)->msg->flags & I2C_M_RD)
+
+static void rcar_i2c_write(struct rcar_i2c_priv *priv, int reg, u32 val)
+{
+	writel(val, priv->io + reg);
+}
+
+static u32 rcar_i2c_read(struct rcar_i2c_priv *priv, int reg)
+{
+	return readl(priv->io + reg);
+}
+
+static void rcar_i2c_clear_irq(struct rcar_i2c_priv *priv, u32 val)
+{
+	writel(~val & 0x7f, priv->io + ICMSR);
+}
+
+static int rcar_i2c_get_scl(struct i2c_adapter *adap)
+{
+	struct rcar_i2c_priv *priv = i2c_get_adapdata(adap);
+
+	return !!(rcar_i2c_read(priv, ICMCR) & FSCL);
+
+};
+
+static void rcar_i2c_set_scl(struct i2c_adapter *adap, int val)
+{
+	struct rcar_i2c_priv *priv = i2c_get_adapdata(adap);
+
+	if (val)
+		priv->recovery_icmcr |= FSCL;
+	else
+		priv->recovery_icmcr &= ~FSCL;
+
+	rcar_i2c_write(priv, ICMCR, priv->recovery_icmcr);
+};
+
+static void rcar_i2c_set_sda(struct i2c_adapter *adap, int val)
+{
+	struct rcar_i2c_priv *priv = i2c_get_adapdata(adap);
+
+	if (val)
+		priv->recovery_icmcr |= FSDA;
+	else
+		priv->recovery_icmcr &= ~FSDA;
+
+	rcar_i2c_write(priv, ICMCR, priv->recovery_icmcr);
+};
+
+static int rcar_i2c_get_bus_free(struct i2c_adapter *adap)
+{
+	struct rcar_i2c_priv *priv = i2c_get_adapdata(adap);
+
+	return !(rcar_i2c_read(priv, ICMCR) & FSDA);
+
+};
+
+static struct i2c_bus_recovery_info rcar_i2c_bri = {
+	.get_scl = rcar_i2c_get_scl,
+	.set_scl = rcar_i2c_set_scl,
+	.set_sda = rcar_i2c_set_sda,
+	.get_bus_free = rcar_i2c_get_bus_free,
+	.recover_bus = i2c_generic_scl_recovery,
+};
+static void rcar_i2c_init(struct rcar_i2c_priv *priv)
+{
+	/* reset master mode */
+	rcar_i2c_write(priv, ICMIER, 0);
+	rcar_i2c_write(priv, ICMCR, MDBS);
+	rcar_i2c_write(priv, ICMSR, 0);
+	/* start clock */
+	rcar_i2c_write(priv, ICCCR, priv->icccr);
+
+	if (priv->devtype == I2C_RCAR_GEN3)
+		rcar_i2c_write(priv, ICFBSCR, TCYC17);
+
+}
+
+static int rcar_i2c_bus_barrier(struct rcar_i2c_priv *priv)
+{
+	int ret;
+	u32 val;
+
+	ret = readl_poll_timeout(priv->io + ICMCR, val, !(val & FSDA), 10,
+				 priv->adap.timeout);
+	if (ret) {
+		/* Waiting did not help, try to recover */
+		priv->recovery_icmcr = MDBS | OBPC | FSDA | FSCL;
+		ret = i2c_recover_bus(&priv->adap);
+	}
+
+	return ret;
+}
+
+static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv)
+{
+	u32 scgd, cdf, round, ick, sum, scl, cdf_width;
+	unsigned long rate;
+	struct device *dev = rcar_i2c_priv_to_dev(priv);
+	struct i2c_timings t = {
+		.bus_freq_hz		= I2C_MAX_STANDARD_MODE_FREQ,
+		.scl_fall_ns		= 35,
+		.scl_rise_ns		= 200,
+		.scl_int_delay_ns	= 50,
+	};
+
+	/* Fall back to previously used values if not supplied */
+	i2c_parse_fw_timings(dev, &t, false);
+
+	switch (priv->devtype) {
+	case I2C_RCAR_GEN1:
+		cdf_width = 2;
+		break;
+	case I2C_RCAR_GEN2:
+	case I2C_RCAR_GEN3:
+		cdf_width = 3;
+		break;
+	default:
+		dev_err(dev, "device type error\n");
+		return -EIO;
+	}
+
+	/*
+	 * calculate SCL clock
+	 * see
+	 *	ICCCR
+	 *
+	 * ick	= clkp / (1 + CDF)
+	 * SCL	= ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick])
+	 *
+	 * ick  : I2C internal clock < 20 MHz
+	 * ticf : I2C SCL falling time
+	 * tr   : I2C SCL rising  time
+	 * intd : LSI internal delay
+	 * clkp : peripheral_clk
+	 * F[]  : integer up-valuation
+	 */
+	rate = clk_get_rate(priv->clk);
+	cdf = rate / 20000000;
+	if (cdf >= 1U << cdf_width) {
+		dev_err(dev, "Input clock %lu too high\n", rate);
+		return -EIO;
+	}
+	ick = rate / (cdf + 1);
+
+	/*
+	 * it is impossible to calculate large scale
+	 * number on u32. separate it
+	 *
+	 * F[(ticf + tr + intd) * ick] with sum = (ticf + tr + intd)
+	 *  = F[sum * ick / 1000000000]
+	 *  = F[(ick / 1000000) * sum / 1000]
+	 */
+	sum = t.scl_fall_ns + t.scl_rise_ns + t.scl_int_delay_ns;
+	round = (ick + 500000) / 1000000 * sum;
+	round = (round + 500) / 1000;
+
+	/*
+	 * SCL	= ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick])
+	 *
+	 * Calculation result (= SCL) should be less than
+	 * bus_speed for hardware safety
+	 *
+	 * We could use something along the lines of
+	 *	div = ick / (bus_speed + 1) + 1;
+	 *	scgd = (div - 20 - round + 7) / 8;
+	 *	scl = ick / (20 + (scgd * 8) + round);
+	 * (not fully verified) but that would get pretty involved
+	 */
+	for (scgd = 0; scgd < 0x40; scgd++) {
+		scl = ick / (20 + (scgd * 8) + round);
+		if (scl <= t.bus_freq_hz)
+			goto scgd_find;
+	}
+	dev_err(dev, "it is impossible to calculate best SCL\n");
+	return -EIO;
+
+scgd_find:
+	dev_dbg(dev, "clk %d/%d(%lu), round %u, CDF:0x%x, SCGD: 0x%x\n",
+		scl, t.bus_freq_hz, rate, round, cdf, scgd);
+
+	/* keep icccr value */
+	priv->icccr = scgd << cdf_width | cdf;
+
+	return 0;
+}
+
+/*
+ * We don't have a test case but the HW engineers say that the write order of
+ * ICMSR and ICMCR depends on whether we issue START or REP_START. So, ICMSR
+ * handling is outside of this function. First messages clear ICMSR before this
+ * function, interrupt handlers clear the relevant bits after this function.
+ */
+static void rcar_i2c_prepare_msg(struct rcar_i2c_priv *priv)
+{
+	int read = !!rcar_i2c_is_recv(priv);
+	bool rep_start = !(priv->flags & ID_REP_AFTER_RD);
+
+	priv->pos = 0;
+	priv->flags &= ID_P_MASK;
+
+	if (priv->msgs_left == 1)
+		priv->flags |= ID_LAST_MSG;
+
+	rcar_i2c_write(priv, ICMAR, i2c_8bit_addr_from_msg(priv->msg));
+	if (priv->flags & ID_P_NOT_ATOMIC)
+		rcar_i2c_write(priv, ICMIER, read ? RCAR_IRQ_RECV : RCAR_IRQ_SEND);
+
+	if (rep_start)
+		rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_START);
+}
+
+static void rcar_i2c_first_msg(struct rcar_i2c_priv *priv,
+			       struct i2c_msg *msgs, int num)
+{
+	priv->msg = msgs;
+	priv->msgs_left = num;
+	rcar_i2c_write(priv, ICMSR, 0); /* must be before preparing msg */
+	rcar_i2c_prepare_msg(priv);
+}
+
+static void rcar_i2c_next_msg(struct rcar_i2c_priv *priv)
+{
+	priv->msg++;
+	priv->msgs_left--;
+	rcar_i2c_prepare_msg(priv);
+	/* ICMSR handling must come afterwards in the irq handler */
+}
+
+static void rcar_i2c_cleanup_dma(struct rcar_i2c_priv *priv, bool terminate)
+{
+	struct dma_chan *chan = priv->dma_direction == DMA_FROM_DEVICE
+		? priv->dma_rx : priv->dma_tx;
+
+	/* only allowed from thread context! */
+	if (terminate)
+		dmaengine_terminate_sync(chan);
+
+	dma_unmap_single(chan->device->dev, sg_dma_address(&priv->sg),
+			 sg_dma_len(&priv->sg), priv->dma_direction);
+
+	/* Gen3 can only do one RXDMA per transfer and we just completed it */
+	if (priv->devtype == I2C_RCAR_GEN3 &&
+	    priv->dma_direction == DMA_FROM_DEVICE)
+		priv->flags |= ID_P_NO_RXDMA;
+
+	priv->dma_direction = DMA_NONE;
+
+	/* Disable DMA Master Received/Transmitted, must be last! */
+	rcar_i2c_write(priv, ICDMAER, 0);
+}
+
+static void rcar_i2c_dma_callback(void *data)
+{
+	struct rcar_i2c_priv *priv = data;
+
+	priv->pos += sg_dma_len(&priv->sg);
+
+	rcar_i2c_cleanup_dma(priv, false);
+}
+
+static bool rcar_i2c_dma(struct rcar_i2c_priv *priv)
+{
+	struct device *dev = rcar_i2c_priv_to_dev(priv);
+	struct i2c_msg *msg = priv->msg;
+	bool read = msg->flags & I2C_M_RD;
+	enum dma_data_direction dir = read ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
+	struct dma_chan *chan = read ? priv->dma_rx : priv->dma_tx;
+	struct dma_async_tx_descriptor *txdesc;
+	dma_addr_t dma_addr;
+	dma_cookie_t cookie;
+	unsigned char *buf;
+	int len;
+
+	/* Do various checks to see if DMA is feasible at all */
+	if (!(priv->flags & ID_P_NOT_ATOMIC) || IS_ERR(chan) || msg->len < RCAR_MIN_DMA_LEN ||
+	    !(msg->flags & I2C_M_DMA_SAFE) || (read && priv->flags & ID_P_NO_RXDMA))
+		return false;
+
+	if (read) {
+		/*
+		 * The last two bytes needs to be fetched using PIO in
+		 * order for the STOP phase to work.
+		 */
+		buf = priv->msg->buf;
+		len = priv->msg->len - 2;
+	} else {
+		/*
+		 * First byte in message was sent using PIO.
+		 */
+		buf = priv->msg->buf + 1;
+		len = priv->msg->len - 1;
+	}
+
+	dma_addr = dma_map_single(chan->device->dev, buf, len, dir);
+	if (dma_mapping_error(chan->device->dev, dma_addr)) {
+		dev_dbg(dev, "dma map failed, using PIO\n");
+		return false;
+	}
+
+	sg_dma_len(&priv->sg) = len;
+	sg_dma_address(&priv->sg) = dma_addr;
+
+	priv->dma_direction = dir;
+
+	txdesc = dmaengine_prep_slave_sg(chan, &priv->sg, 1,
+					 read ? DMA_DEV_TO_MEM : DMA_MEM_TO_DEV,
+					 DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	if (!txdesc) {
+		dev_dbg(dev, "dma prep slave sg failed, using PIO\n");
+		rcar_i2c_cleanup_dma(priv, false);
+		return false;
+	}
+
+	txdesc->callback = rcar_i2c_dma_callback;
+	txdesc->callback_param = priv;
+
+	cookie = dmaengine_submit(txdesc);
+	if (dma_submit_error(cookie)) {
+		dev_dbg(dev, "submitting dma failed, using PIO\n");
+		rcar_i2c_cleanup_dma(priv, false);
+		return false;
+	}
+
+	/* Enable DMA Master Received/Transmitted */
+	if (read)
+		rcar_i2c_write(priv, ICDMAER, RMDMAE);
+	else
+		rcar_i2c_write(priv, ICDMAER, TMDMAE);
+
+	dma_async_issue_pending(chan);
+	return true;
+}
+
+static void rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)
+{
+	struct i2c_msg *msg = priv->msg;
+	u32 irqs_to_clear = MDE;
+
+	/* FIXME: sometimes, unknown interrupt happened. Do nothing */
+	if (!(msr & MDE))
+		return;
+
+	if (msr & MAT)
+		irqs_to_clear |= MAT;
+
+	/* Check if DMA can be enabled and take over */
+	if (priv->pos == 1 && rcar_i2c_dma(priv))
+		return;
+
+	if (priv->pos < msg->len) {
+		/*
+		 * Prepare next data to ICRXTX register.
+		 * This data will go to _SHIFT_ register.
+		 *
+		 *    *
+		 * [ICRXTX] -> [SHIFT] -> [I2C bus]
+		 */
+		rcar_i2c_write(priv, ICRXTX, msg->buf[priv->pos]);
+		priv->pos++;
+	} else {
+		/*
+		 * The last data was pushed to ICRXTX on _PREV_ empty irq.
+		 * It is on _SHIFT_ register, and will sent to I2C bus.
+		 *
+		 *		  *
+		 * [ICRXTX] -> [SHIFT] -> [I2C bus]
+		 */
+
+		if (priv->flags & ID_LAST_MSG)
+			/*
+			 * If current msg is the _LAST_ msg,
+			 * prepare stop condition here.
+			 * ID_DONE will be set on STOP irq.
+			 */
+			rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_STOP);
+		else
+			rcar_i2c_next_msg(priv);
+	}
+
+	rcar_i2c_clear_irq(priv, irqs_to_clear);
+}
+
+static void rcar_i2c_irq_recv(struct rcar_i2c_priv *priv, u32 msr)
+{
+	struct i2c_msg *msg = priv->msg;
+	bool recv_len_init = priv->pos == 0 && msg->flags & I2C_M_RECV_LEN;
+	u32 irqs_to_clear = MDR;
+
+	/* FIXME: sometimes, unknown interrupt happened. Do nothing */
+	if (!(msr & MDR))
+		return;
+
+	if (msr & MAT) {
+		irqs_to_clear |= MAT;
+		/*
+		 * Address transfer phase finished, but no data at this point.
+		 * Try to use DMA to receive data.
+		 */
+		rcar_i2c_dma(priv);
+	} else if (priv->pos < msg->len) {
+		/* get received data */
+		u8 data = rcar_i2c_read(priv, ICRXTX);
+
+		msg->buf[priv->pos] = data;
+		if (recv_len_init) {
+			if (data == 0 || data > I2C_SMBUS_BLOCK_MAX) {
+				priv->flags |= ID_DONE | ID_EPROTO;
+				return;
+			}
+			msg->len += msg->buf[0];
+			/* Enough data for DMA? */
+			if (rcar_i2c_dma(priv))
+				return;
+			/* new length after RECV_LEN now properly initialized */
+			recv_len_init = false;
+		}
+		priv->pos++;
+	}
+
+	/*
+	 * If next received data is the _LAST_ and we are not waiting for a new
+	 * length because of RECV_LEN, then go to a new phase.
+	 */
+	if (priv->pos + 1 == msg->len && !recv_len_init) {
+		if (priv->flags & ID_LAST_MSG) {
+			rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_STOP);
+		} else {
+			rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_START);
+			priv->flags |= ID_REP_AFTER_RD;
+		}
+	}
+
+	if (priv->pos == msg->len && !(priv->flags & ID_LAST_MSG))
+		rcar_i2c_next_msg(priv);
+
+	rcar_i2c_clear_irq(priv, irqs_to_clear);
+}
+
+static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv)
+{
+	u32 ssr_raw, ssr_filtered;
+	u8 value;
+
+	ssr_raw = rcar_i2c_read(priv, ICSSR) & 0xff;
+	ssr_filtered = ssr_raw & rcar_i2c_read(priv, ICSIER);
+
+	if (!ssr_filtered)
+		return false;
+
+	/* address detected */
+	if (ssr_filtered & SAR) {
+		/* read or write request */
+		if (ssr_raw & STM) {
+			i2c_slave_event(priv->slave, I2C_SLAVE_READ_REQUESTED, &value);
+			rcar_i2c_write(priv, ICRXTX, value);
+			rcar_i2c_write(priv, ICSIER, SDE | SSR | SAR);
+		} else {
+			i2c_slave_event(priv->slave, I2C_SLAVE_WRITE_REQUESTED, &value);
+			rcar_i2c_read(priv, ICRXTX);	/* dummy read */
+			rcar_i2c_write(priv, ICSIER, SDR | SSR | SAR);
+		}
+
+		/* Clear SSR, too, because of old STOPs to other clients than us */
+		rcar_i2c_write(priv, ICSSR, ~(SAR | SSR) & 0xff);
+	}
+
+	/* master sent stop */
+	if (ssr_filtered & SSR) {
+		i2c_slave_event(priv->slave, I2C_SLAVE_STOP, &value);
+		rcar_i2c_write(priv, ICSCR, SIE | SDBS); /* clear our NACK */
+		rcar_i2c_write(priv, ICSIER, SAR);
+		rcar_i2c_write(priv, ICSSR, ~SSR & 0xff);
+	}
+
+	/* master wants to write to us */
+	if (ssr_filtered & SDR) {
+		int ret;
+
+		value = rcar_i2c_read(priv, ICRXTX);
+		ret = i2c_slave_event(priv->slave, I2C_SLAVE_WRITE_RECEIVED, &value);
+		/* Send NACK in case of error */
+		rcar_i2c_write(priv, ICSCR, SIE | SDBS | (ret < 0 ? FNA : 0));
+		rcar_i2c_write(priv, ICSSR, ~SDR & 0xff);
+	}
+
+	/* master wants to read from us */
+	if (ssr_filtered & SDE) {
+		i2c_slave_event(priv->slave, I2C_SLAVE_READ_PROCESSED, &value);
+		rcar_i2c_write(priv, ICRXTX, value);
+		rcar_i2c_write(priv, ICSSR, ~SDE & 0xff);
+	}
+
+	return true;
+}
+
+/*
+ * This driver has a lock-free design because there are IP cores (at least
+ * R-Car Gen2) which have an inherent race condition in their hardware design.
+ * There, we need to switch to RCAR_BUS_PHASE_DATA as soon as possible after
+ * the interrupt was generated, otherwise an unwanted repeated message gets
+ * generated. It turned out that taking a spinlock at the beginning of the ISR
+ * was already causing repeated messages. Thus, this driver was converted to
+ * the now lockless behaviour. Please keep this in mind when hacking the driver.
+ * R-Car Gen3 seems to have this fixed but earlier versions than R-Car Gen2 are
+ * likely affected. Therefore, we have different interrupt handler entries.
+ */
+static irqreturn_t rcar_i2c_irq(int irq, struct rcar_i2c_priv *priv, u32 msr)
+{
+	if (!msr) {
+		if (rcar_i2c_slave_irq(priv))
+			return IRQ_HANDLED;
+
+		return IRQ_NONE;
+	}
+
+	/* Arbitration lost */
+	if (msr & MAL) {
+		priv->flags |= ID_DONE | ID_ARBLOST;
+		goto out;
+	}
+
+	/* Nack */
+	if (msr & MNR) {
+		/* HW automatically sends STOP after received NACK */
+		if (priv->flags & ID_P_NOT_ATOMIC)
+			rcar_i2c_write(priv, ICMIER, RCAR_IRQ_STOP);
+		priv->flags |= ID_NACK;
+		goto out;
+	}
+
+	/* Stop */
+	if (msr & MST) {
+		priv->msgs_left--; /* The last message also made it */
+		priv->flags |= ID_DONE;
+		goto out;
+	}
+
+	if (rcar_i2c_is_recv(priv))
+		rcar_i2c_irq_recv(priv, msr);
+	else
+		rcar_i2c_irq_send(priv, msr);
+
+out:
+	if (priv->flags & ID_DONE) {
+		rcar_i2c_write(priv, ICMIER, 0);
+		rcar_i2c_write(priv, ICMSR, 0);
+		if (priv->flags & ID_P_NOT_ATOMIC)
+			wake_up(&priv->wait);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t rcar_i2c_gen2_irq(int irq, void *ptr)
+{
+	struct rcar_i2c_priv *priv = ptr;
+	u32 msr;
+
+	/* Clear START or STOP immediately, except for REPSTART after read */
+	if (likely(!(priv->flags & ID_REP_AFTER_RD)))
+		rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);
+
+	/* Only handle interrupts that are currently enabled */
+	msr = rcar_i2c_read(priv, ICMSR);
+	if (priv->flags & ID_P_NOT_ATOMIC)
+		msr &= rcar_i2c_read(priv, ICMIER);
+
+	return rcar_i2c_irq(irq, priv, msr);
+}
+
+static irqreturn_t rcar_i2c_gen3_irq(int irq, void *ptr)
+{
+	struct rcar_i2c_priv *priv = ptr;
+	u32 msr;
+
+	/* Only handle interrupts that are currently enabled */
+	msr = rcar_i2c_read(priv, ICMSR);
+	if (priv->flags & ID_P_NOT_ATOMIC)
+		msr &= rcar_i2c_read(priv, ICMIER);
+
+	/*
+	 * Clear START or STOP immediately, except for REPSTART after read or
+	 * if a spurious interrupt was detected.
+	 */
+	if (likely(!(priv->flags & ID_REP_AFTER_RD) && msr))
+		rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);
+
+	return rcar_i2c_irq(irq, priv, msr);
+}
+
+static struct dma_chan *rcar_i2c_request_dma_chan(struct device *dev,
+					enum dma_transfer_direction dir,
+					dma_addr_t port_addr)
+{
+	struct dma_chan *chan;
+	struct dma_slave_config cfg;
+	char *chan_name = dir == DMA_MEM_TO_DEV ? "tx" : "rx";
+	int ret;
+
+	chan = dma_request_chan(dev, chan_name);
+	if (IS_ERR(chan)) {
+		dev_dbg(dev, "request_channel failed for %s (%ld)\n",
+			chan_name, PTR_ERR(chan));
+		return chan;
+	}
+
+	memset(&cfg, 0, sizeof(cfg));
+	cfg.direction = dir;
+	if (dir == DMA_MEM_TO_DEV) {
+		cfg.dst_addr = port_addr;
+		cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+	} else {
+		cfg.src_addr = port_addr;
+		cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+	}
+
+	ret = dmaengine_slave_config(chan, &cfg);
+	if (ret) {
+		dev_dbg(dev, "slave_config failed for %s (%d)\n",
+			chan_name, ret);
+		dma_release_channel(chan);
+		return ERR_PTR(ret);
+	}
+
+	dev_dbg(dev, "got DMA channel for %s\n", chan_name);
+	return chan;
+}
+
+static void rcar_i2c_request_dma(struct rcar_i2c_priv *priv,
+				 struct i2c_msg *msg)
+{
+	struct device *dev = rcar_i2c_priv_to_dev(priv);
+	bool read;
+	struct dma_chan *chan;
+	enum dma_transfer_direction dir;
+
+	read = msg->flags & I2C_M_RD;
+
+	chan = read ? priv->dma_rx : priv->dma_tx;
+	if (PTR_ERR(chan) != -EPROBE_DEFER)
+		return;
+
+	dir = read ? DMA_DEV_TO_MEM : DMA_MEM_TO_DEV;
+	chan = rcar_i2c_request_dma_chan(dev, dir, priv->res->start + ICRXTX);
+
+	if (read)
+		priv->dma_rx = chan;
+	else
+		priv->dma_tx = chan;
+}
+
+static void rcar_i2c_release_dma(struct rcar_i2c_priv *priv)
+{
+	if (!IS_ERR(priv->dma_tx)) {
+		dma_release_channel(priv->dma_tx);
+		priv->dma_tx = ERR_PTR(-EPROBE_DEFER);
+	}
+
+	if (!IS_ERR(priv->dma_rx)) {
+		dma_release_channel(priv->dma_rx);
+		priv->dma_rx = ERR_PTR(-EPROBE_DEFER);
+	}
+}
+
+/* I2C is a special case, we need to poll the status of a reset */
+static int rcar_i2c_do_reset(struct rcar_i2c_priv *priv)
+{
+	int ret;
+
+	ret = reset_control_reset(priv->rstc);
+	if (ret)
+		return ret;
+
+	return read_poll_timeout_atomic(reset_control_status, ret, ret == 0, 1,
+					100, false, priv->rstc);
+}
+
+static int rcar_i2c_master_xfer(struct i2c_adapter *adap,
+				struct i2c_msg *msgs,
+				int num)
+{
+	struct rcar_i2c_priv *priv = i2c_get_adapdata(adap);
+	struct device *dev = rcar_i2c_priv_to_dev(priv);
+	int i, ret;
+	long time_left;
+
+	priv->flags |= ID_P_NOT_ATOMIC;
+
+	pm_runtime_get_sync(dev);
+
+	/* Check bus state before init otherwise bus busy info will be lost */
+	ret = rcar_i2c_bus_barrier(priv);
+	if (ret < 0)
+		goto out;
+
+	/* Gen3 needs a reset before allowing RXDMA once */
+	if (priv->devtype == I2C_RCAR_GEN3) {
+		priv->flags |= ID_P_NO_RXDMA;
+		if (!IS_ERR(priv->rstc)) {
+			ret = rcar_i2c_do_reset(priv);
+			if (ret == 0)
+				priv->flags &= ~ID_P_NO_RXDMA;
+		}
+	}
+
+	rcar_i2c_init(priv);
+
+	for (i = 0; i < num; i++)
+		rcar_i2c_request_dma(priv, msgs + i);
+
+	rcar_i2c_first_msg(priv, msgs, num);
+
+	time_left = wait_event_timeout(priv->wait, priv->flags & ID_DONE,
+				     num * adap->timeout);
+
+	/* cleanup DMA if it couldn't complete properly due to an error */
+	if (priv->dma_direction != DMA_NONE)
+		rcar_i2c_cleanup_dma(priv, true);
+
+	if (!time_left) {
+		rcar_i2c_init(priv);
+		ret = -ETIMEDOUT;
+	} else if (priv->flags & ID_NACK) {
+		ret = -ENXIO;
+	} else if (priv->flags & ID_ARBLOST) {
+		ret = -EAGAIN;
+	} else if (priv->flags & ID_EPROTO) {
+		ret = -EPROTO;
+	} else {
+		ret = num - priv->msgs_left; /* The number of transfer */
+	}
+out:
+	pm_runtime_put(dev);
+
+	if (ret < 0 && ret != -ENXIO)
+		dev_err(dev, "error %d : %x\n", ret, priv->flags);
+
+	return ret;
+}
+
+static int rcar_i2c_master_xfer_atomic(struct i2c_adapter *adap,
+				struct i2c_msg *msgs,
+				int num)
+{
+	struct rcar_i2c_priv *priv = i2c_get_adapdata(adap);
+	struct device *dev = rcar_i2c_priv_to_dev(priv);
+	unsigned long j;
+	bool time_left;
+	int ret;
+
+	priv->flags &= ~ID_P_NOT_ATOMIC;
+
+	pm_runtime_get_sync(dev);
+
+	/* Check bus state before init otherwise bus busy info will be lost */
+	ret = rcar_i2c_bus_barrier(priv);
+	if (ret < 0)
+		goto out;
+
+	rcar_i2c_init(priv);
+	rcar_i2c_first_msg(priv, msgs, num);
+
+	j = jiffies + num * adap->timeout;
+	do {
+		u32 msr = rcar_i2c_read(priv, ICMSR);
+
+		msr &= (rcar_i2c_is_recv(priv) ? RCAR_IRQ_RECV : RCAR_IRQ_SEND) | RCAR_IRQ_STOP;
+
+		if (msr) {
+			if (priv->devtype < I2C_RCAR_GEN3)
+				rcar_i2c_gen2_irq(0, priv);
+			else
+				rcar_i2c_gen3_irq(0, priv);
+		}
+
+		time_left = time_before_eq(jiffies, j);
+	} while (!(priv->flags & ID_DONE) && time_left);
+
+	if (!time_left) {
+		rcar_i2c_init(priv);
+		ret = -ETIMEDOUT;
+	} else if (priv->flags & ID_NACK) {
+		ret = -ENXIO;
+	} else if (priv->flags & ID_ARBLOST) {
+		ret = -EAGAIN;
+	} else if (priv->flags & ID_EPROTO) {
+		ret = -EPROTO;
+	} else {
+		ret = num - priv->msgs_left; /* The number of transfer */
+	}
+out:
+	pm_runtime_put(dev);
+
+	if (ret < 0 && ret != -ENXIO)
+		dev_err(dev, "error %d : %x\n", ret, priv->flags);
+
+	return ret;
+}
+
+static int rcar_reg_slave(struct i2c_client *slave)
+{
+	struct rcar_i2c_priv *priv = i2c_get_adapdata(slave->adapter);
+
+	if (priv->slave)
+		return -EBUSY;
+
+	if (slave->flags & I2C_CLIENT_TEN)
+		return -EAFNOSUPPORT;
+
+	/* Keep device active for slave address detection logic */
+	pm_runtime_get_sync(rcar_i2c_priv_to_dev(priv));
+
+	priv->slave = slave;
+	rcar_i2c_write(priv, ICSAR, slave->addr);
+	rcar_i2c_write(priv, ICSSR, 0);
+	rcar_i2c_write(priv, ICSIER, SAR);
+	rcar_i2c_write(priv, ICSCR, SIE | SDBS);
+
+	return 0;
+}
+
+static int rcar_unreg_slave(struct i2c_client *slave)
+{
+	struct rcar_i2c_priv *priv = i2c_get_adapdata(slave->adapter);
+
+	WARN_ON(!priv->slave);
+
+	/* ensure no irq is running before clearing ptr */
+	disable_irq(priv->irq);
+	rcar_i2c_write(priv, ICSIER, 0);
+	rcar_i2c_write(priv, ICSSR, 0);
+	enable_irq(priv->irq);
+	rcar_i2c_write(priv, ICSCR, SDBS);
+	rcar_i2c_write(priv, ICSAR, 0); /* Gen2: must be 0 if not using slave */
+
+	priv->slave = NULL;
+
+	pm_runtime_put(rcar_i2c_priv_to_dev(priv));
+
+	return 0;
+}
+
+static u32 rcar_i2c_func(struct i2c_adapter *adap)
+{
+	struct rcar_i2c_priv *priv = i2c_get_adapdata(adap);
+
+	/*
+	 * This HW can't do:
+	 * I2C_SMBUS_QUICK (setting FSB during START didn't work)
+	 * I2C_M_NOSTART (automatically sends address after START)
+	 * I2C_M_IGNORE_NAK (automatically sends STOP after NAK)
+	 */
+	u32 func = I2C_FUNC_I2C | I2C_FUNC_SLAVE |
+		   (I2C_FUNC_SMBUS_EMUL_ALL & ~I2C_FUNC_SMBUS_QUICK);
+
+	if (priv->flags & ID_P_HOST_NOTIFY)
+		func |= I2C_FUNC_SMBUS_HOST_NOTIFY;
+
+	return func;
+}
+
+static const struct i2c_algorithm rcar_i2c_algo = {
+	.master_xfer	= rcar_i2c_master_xfer,
+	.master_xfer_atomic = rcar_i2c_master_xfer_atomic,
+	.functionality	= rcar_i2c_func,
+	.reg_slave	= rcar_reg_slave,
+	.unreg_slave	= rcar_unreg_slave,
+};
+
+static const struct i2c_adapter_quirks rcar_i2c_quirks = {
+	.flags = I2C_AQ_NO_ZERO_LEN,
+};
+
+static const struct of_device_id rcar_i2c_dt_ids[] = {
+	{ .compatible = "renesas,i2c-r8a7778", .data = (void *)I2C_RCAR_GEN1 },
+	{ .compatible = "renesas,i2c-r8a7779", .data = (void *)I2C_RCAR_GEN1 },
+	{ .compatible = "renesas,i2c-r8a7790", .data = (void *)I2C_RCAR_GEN2 },
+	{ .compatible = "renesas,i2c-r8a7791", .data = (void *)I2C_RCAR_GEN2 },
+	{ .compatible = "renesas,i2c-r8a7792", .data = (void *)I2C_RCAR_GEN2 },
+	{ .compatible = "renesas,i2c-r8a7793", .data = (void *)I2C_RCAR_GEN2 },
+	{ .compatible = "renesas,i2c-r8a7794", .data = (void *)I2C_RCAR_GEN2 },
+	{ .compatible = "renesas,i2c-r8a7795", .data = (void *)I2C_RCAR_GEN3 },
+	{ .compatible = "renesas,i2c-r8a7796", .data = (void *)I2C_RCAR_GEN3 },
+	{ .compatible = "renesas,rcar-gen1-i2c", .data = (void *)I2C_RCAR_GEN1 },
+	{ .compatible = "renesas,rcar-gen2-i2c", .data = (void *)I2C_RCAR_GEN2 },
+	{ .compatible = "renesas,rcar-gen3-i2c", .data = (void *)I2C_RCAR_GEN3 },
+	{ .compatible = "renesas,rcar-gen4-i2c", .data = (void *)I2C_RCAR_GEN3 },
+	{},
+};
+MODULE_DEVICE_TABLE(of, rcar_i2c_dt_ids);
+
+static int rcar_i2c_probe(struct platform_device *pdev)
+{
+	struct rcar_i2c_priv *priv;
+	struct i2c_adapter *adap;
+	struct device *dev = &pdev->dev;
+	unsigned long irqflags = 0;
+	irqreturn_t (*irqhandler)(int irq, void *ptr) = rcar_i2c_gen3_irq;
+	int ret;
+
+	/* Otherwise logic will break because some bytes must always use PIO */
+	BUILD_BUG_ON_MSG(RCAR_MIN_DMA_LEN < 3, "Invalid min DMA length");
+
+	priv = devm_kzalloc(dev, sizeof(struct rcar_i2c_priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(priv->clk)) {
+		dev_err(dev, "cannot get clock\n");
+		return PTR_ERR(priv->clk);
+	}
+
+	priv->io = devm_platform_get_and_ioremap_resource(pdev, 0, &priv->res);
+	if (IS_ERR(priv->io))
+		return PTR_ERR(priv->io);
+
+	priv->devtype = (enum rcar_i2c_type)of_device_get_match_data(dev);
+	init_waitqueue_head(&priv->wait);
+
+	adap = &priv->adap;
+	adap->nr = pdev->id;
+	adap->algo = &rcar_i2c_algo;
+	adap->class = I2C_CLASS_DEPRECATED;
+	adap->retries = 3;
+	adap->dev.parent = dev;
+	adap->dev.of_node = dev->of_node;
+	adap->bus_recovery_info = &rcar_i2c_bri;
+	adap->quirks = &rcar_i2c_quirks;
+	i2c_set_adapdata(adap, priv);
+	strscpy(adap->name, pdev->name, sizeof(adap->name));
+
+	/* Init DMA */
+	sg_init_table(&priv->sg, 1);
+	priv->dma_direction = DMA_NONE;
+	priv->dma_rx = priv->dma_tx = ERR_PTR(-EPROBE_DEFER);
+
+	/* Activate device for clock calculation */
+	pm_runtime_enable(dev);
+	pm_runtime_get_sync(dev);
+	ret = rcar_i2c_clock_calculate(priv);
+	if (ret < 0) {
+		pm_runtime_put(dev);
+		goto out_pm_disable;
+	}
+
+	rcar_i2c_write(priv, ICSAR, 0); /* Gen2: must be 0 if not using slave */
+
+	if (priv->devtype < I2C_RCAR_GEN3) {
+		irqflags |= IRQF_NO_THREAD;
+		irqhandler = rcar_i2c_gen2_irq;
+	}
+
+	if (priv->devtype == I2C_RCAR_GEN3) {
+		priv->rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
+		if (!IS_ERR(priv->rstc)) {
+			ret = reset_control_status(priv->rstc);
+			if (ret < 0)
+				priv->rstc = ERR_PTR(-ENOTSUPP);
+		}
+	}
+
+	/* Stay always active when multi-master to keep arbitration working */
+	if (of_property_read_bool(dev->of_node, "multi-master"))
+		priv->flags |= ID_P_PM_BLOCKED;
+	else
+		pm_runtime_put(dev);
+
+	if (of_property_read_bool(dev->of_node, "smbus"))
+		priv->flags |= ID_P_HOST_NOTIFY;
+
+	ret = platform_get_irq(pdev, 0);
+	if (ret < 0)
+		goto out_pm_put;
+	priv->irq = ret;
+	ret = devm_request_irq(dev, priv->irq, irqhandler, irqflags, dev_name(dev), priv);
+	if (ret < 0) {
+		dev_err(dev, "cannot get irq %d\n", priv->irq);
+		goto out_pm_put;
+	}
+
+	platform_set_drvdata(pdev, priv);
+
+	ret = i2c_add_numbered_adapter(adap);
+	if (ret < 0)
+		goto out_pm_put;
+
+	if (priv->flags & ID_P_HOST_NOTIFY) {
+		priv->host_notify_client = i2c_new_slave_host_notify_device(adap);
+		if (IS_ERR(priv->host_notify_client)) {
+			ret = PTR_ERR(priv->host_notify_client);
+			goto out_del_device;
+		}
+	}
+
+	dev_info(dev, "probed\n");
+
+	return 0;
+
+ out_del_device:
+	i2c_del_adapter(&priv->adap);
+ out_pm_put:
+	if (priv->flags & ID_P_PM_BLOCKED)
+		pm_runtime_put(dev);
+ out_pm_disable:
+	pm_runtime_disable(dev);
+	return ret;
+}
+
+static int rcar_i2c_remove(struct platform_device *pdev)
+{
+	struct rcar_i2c_priv *priv = platform_get_drvdata(pdev);
+	struct device *dev = &pdev->dev;
+
+	if (priv->host_notify_client)
+		i2c_free_slave_host_notify_device(priv->host_notify_client);
+	i2c_del_adapter(&priv->adap);
+	rcar_i2c_release_dma(priv);
+	if (priv->flags & ID_P_PM_BLOCKED)
+		pm_runtime_put(dev);
+	pm_runtime_disable(dev);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int rcar_i2c_suspend(struct device *dev)
+{
+	struct rcar_i2c_priv *priv = dev_get_drvdata(dev);
+
+	i2c_mark_adapter_suspended(&priv->adap);
+	return 0;
+}
+
+static int rcar_i2c_resume(struct device *dev)
+{
+	struct rcar_i2c_priv *priv = dev_get_drvdata(dev);
+
+	i2c_mark_adapter_resumed(&priv->adap);
+	return 0;
+}
+
+static const struct dev_pm_ops rcar_i2c_pm_ops = {
+	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(rcar_i2c_suspend, rcar_i2c_resume)
+};
+
+#define DEV_PM_OPS (&rcar_i2c_pm_ops)
+#else
+#define DEV_PM_OPS NULL
+#endif /* CONFIG_PM_SLEEP */
+
+static struct platform_driver rcar_i2c_driver = {
+	.driver	= {
+		.name	= "i2c-rcar",
+		.of_match_table = rcar_i2c_dt_ids,
+		.pm	= DEV_PM_OPS,
+	},
+	.probe		= rcar_i2c_probe,
+	.remove		= rcar_i2c_remove,
+};
+
+module_platform_driver(rcar_i2c_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Renesas R-Car I2C bus driver");
+MODULE_AUTHOR("Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>");