drivers/i2c/busses/i2c-hisi.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * HiSilicon I2C Controller Driver for Kunpeng SoC
  *
  * Copyright (c) 2021 HiSilicon Technologies Co., Ltd.
  */

 #include <linux/bits.h>
 #include <linux/bitfield.h>
 #include <linux/clk.h>
 #include <linux/completion.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
 #include <linux/platform_device.h>
 #include <linux/property.h>
 #include <linux/units.h>

 #define HISI_I2C_FRAME_CTRL		0x0000
 #define   HISI_I2C_FRAME_CTRL_SPEED_MODE	GENMASK(1, 0)
 #define   HISI_I2C_FRAME_CTRL_ADDR_TEN	BIT(2)
 #define HISI_I2C_SLV_ADDR		0x0004
 #define   HISI_I2C_SLV_ADDR_VAL		GENMASK(9, 0)
 #define   HISI_I2C_SLV_ADDR_GC_S_MODE	BIT(10)
 #define   HISI_I2C_SLV_ADDR_GC_S_EN	BIT(11)
 #define HISI_I2C_CMD_TXDATA		0x0008
 #define   HISI_I2C_CMD_TXDATA_DATA	GENMASK(7, 0)
 #define   HISI_I2C_CMD_TXDATA_RW	BIT(8)
 #define   HISI_I2C_CMD_TXDATA_P_EN	BIT(9)
 #define   HISI_I2C_CMD_TXDATA_SR_EN	BIT(10)
 #define HISI_I2C_RXDATA			0x000c
 #define   HISI_I2C_RXDATA_DATA		GENMASK(7, 0)
 #define HISI_I2C_SS_SCL_HCNT		0x0010
 #define HISI_I2C_SS_SCL_LCNT		0x0014
 #define HISI_I2C_FS_SCL_HCNT		0x0018
 #define HISI_I2C_FS_SCL_LCNT		0x001c
 #define HISI_I2C_HS_SCL_HCNT		0x0020
 #define HISI_I2C_HS_SCL_LCNT		0x0024
 #define HISI_I2C_FIFO_CTRL		0x0028
 #define   HISI_I2C_FIFO_RX_CLR		BIT(0)
 #define   HISI_I2C_FIFO_TX_CLR		BIT(1)
 #define   HISI_I2C_FIFO_RX_AF_THRESH	GENMASK(7, 2)
 #define   HISI_I2C_FIFO_TX_AE_THRESH	GENMASK(13, 8)
 #define HISI_I2C_FIFO_STATE		0x002c
 #define   HISI_I2C_FIFO_STATE_RX_RERR	BIT(0)
 #define   HISI_I2C_FIFO_STATE_RX_WERR	BIT(1)
 #define   HISI_I2C_FIFO_STATE_RX_EMPTY	BIT(3)
 #define   HISI_I2C_FIFO_STATE_TX_RERR	BIT(6)
 #define   HISI_I2C_FIFO_STATE_TX_WERR	BIT(7)
 #define   HISI_I2C_FIFO_STATE_TX_FULL	BIT(11)
 #define HISI_I2C_SDA_HOLD		0x0030
 #define   HISI_I2C_SDA_HOLD_TX		GENMASK(15, 0)
 #define   HISI_I2C_SDA_HOLD_RX		GENMASK(23, 16)
 #define HISI_I2C_FS_SPK_LEN		0x0038
 #define   HISI_I2C_FS_SPK_LEN_CNT	GENMASK(7, 0)
 #define HISI_I2C_HS_SPK_LEN		0x003c
 #define   HISI_I2C_HS_SPK_LEN_CNT	GENMASK(7, 0)
 #define HISI_I2C_INT_MSTAT		0x0044
 #define HISI_I2C_INT_CLR		0x0048
 #define HISI_I2C_INT_MASK		0x004C
 #define HISI_I2C_TRANS_STATE		0x0050
 #define HISI_I2C_TRANS_ERR		0x0054
 #define HISI_I2C_VERSION		0x0058

 #define HISI_I2C_INT_ALL	GENMASK(4, 0)
 #define HISI_I2C_INT_TRANS_CPLT	BIT(0)
 #define HISI_I2C_INT_TRANS_ERR	BIT(1)
 #define HISI_I2C_INT_FIFO_ERR	BIT(2)
 #define HISI_I2C_INT_RX_FULL	BIT(3)
 #define HISI_I2C_INT_TX_EMPTY	BIT(4)
 #define HISI_I2C_INT_ERR \
 	(HISI_I2C_INT_TRANS_ERR | HISI_I2C_INT_FIFO_ERR)

 #define HISI_I2C_STD_SPEED_MODE		0
 #define HISI_I2C_FAST_SPEED_MODE	1
 #define HISI_I2C_HIGH_SPEED_MODE	2

 #define HISI_I2C_TX_FIFO_DEPTH		64
 #define HISI_I2C_RX_FIFO_DEPTH		64
 #define HISI_I2C_TX_F_AE_THRESH		1
 #define HISI_I2C_RX_F_AF_THRESH		60

 #define NSEC_TO_CYCLES(ns, clk_rate_khz) \
 	DIV_ROUND_UP_ULL((clk_rate_khz) * (ns), NSEC_PER_MSEC)

 struct hisi_i2c_controller {
 	struct i2c_adapter adapter;
 	void __iomem *iobase;
 	struct device *dev;
 	struct clk *clk;
 	int irq;

 	/* Intermediates for recording the transfer process */
 	struct completion *completion;
 	struct i2c_msg *msgs;
 	int msg_num;
 	int msg_tx_idx;
 	int buf_tx_idx;
 	int msg_rx_idx;
 	int buf_rx_idx;
 	u16 tar_addr;
 	u32 xfer_err;

 	/* I2C bus configuration */
 	struct i2c_timings t;
 	u32 clk_rate_khz;
 	u32 spk_len;
 };

 static void hisi_i2c_enable_int(struct hisi_i2c_controller *ctlr, u32 mask)
 {
 	writel_relaxed(mask, ctlr->iobase + HISI_I2C_INT_MASK);
 }

 static void hisi_i2c_disable_int(struct hisi_i2c_controller *ctlr, u32 mask)
 {
 	writel_relaxed((~mask) & HISI_I2C_INT_ALL, ctlr->iobase + HISI_I2C_INT_MASK);
 }

 static void hisi_i2c_clear_int(struct hisi_i2c_controller *ctlr, u32 mask)
 {
 	writel_relaxed(mask, ctlr->iobase + HISI_I2C_INT_CLR);
 }

 static void hisi_i2c_handle_errors(struct hisi_i2c_controller *ctlr)
 {
 	u32 int_err = ctlr->xfer_err, reg;

 	if (int_err & HISI_I2C_INT_FIFO_ERR) {
 		reg = readl(ctlr->iobase + HISI_I2C_FIFO_STATE);

 		if (reg & HISI_I2C_FIFO_STATE_RX_RERR)
 			dev_err(ctlr->dev, "rx fifo error read\n");

 		if (reg & HISI_I2C_FIFO_STATE_RX_WERR)
 			dev_err(ctlr->dev, "rx fifo error write\n");

 		if (reg & HISI_I2C_FIFO_STATE_TX_RERR)
 			dev_err(ctlr->dev, "tx fifo error read\n");

 		if (reg & HISI_I2C_FIFO_STATE_TX_WERR)
 			dev_err(ctlr->dev, "tx fifo error write\n");
 	}
 }

 static int hisi_i2c_start_xfer(struct hisi_i2c_controller *ctlr)
 {
 	struct i2c_msg *msg = ctlr->msgs;
 	u32 reg;

 	reg = readl(ctlr->iobase + HISI_I2C_FRAME_CTRL);
 	reg &= ~HISI_I2C_FRAME_CTRL_ADDR_TEN;
 	if (msg->flags & I2C_M_TEN)
 		reg |= HISI_I2C_FRAME_CTRL_ADDR_TEN;
 	writel(reg, ctlr->iobase + HISI_I2C_FRAME_CTRL);

 	reg = readl(ctlr->iobase + HISI_I2C_SLV_ADDR);
 	reg &= ~HISI_I2C_SLV_ADDR_VAL;
 	reg |= FIELD_PREP(HISI_I2C_SLV_ADDR_VAL, msg->addr);
 	writel(reg, ctlr->iobase + HISI_I2C_SLV_ADDR);

 	reg = readl(ctlr->iobase + HISI_I2C_FIFO_CTRL);
 	reg |= HISI_I2C_FIFO_RX_CLR | HISI_I2C_FIFO_TX_CLR;
 	writel(reg, ctlr->iobase + HISI_I2C_FIFO_CTRL);
 	reg &= ~(HISI_I2C_FIFO_RX_CLR | HISI_I2C_FIFO_TX_CLR);
 	writel(reg, ctlr->iobase + HISI_I2C_FIFO_CTRL);

 	hisi_i2c_clear_int(ctlr, HISI_I2C_INT_ALL);
 	hisi_i2c_enable_int(ctlr, HISI_I2C_INT_ALL);

 	return 0;
 }

 static void hisi_i2c_reset_xfer(struct hisi_i2c_controller *ctlr)
 {
 	ctlr->msg_num = 0;
 	ctlr->xfer_err = 0;
 	ctlr->msg_tx_idx = 0;
 	ctlr->msg_rx_idx = 0;
 	ctlr->buf_tx_idx = 0;
 	ctlr->buf_rx_idx = 0;
 }

 /*
  * Initialize the transfer information and start the I2C bus transfer.
  * We only configure the transfer and do some pre/post works here, and
  * wait for the transfer done. The major transfer process is performed
  * in the IRQ handler.
  */
 static int hisi_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 				int num)
 {
 	struct hisi_i2c_controller *ctlr = i2c_get_adapdata(adap);
 	DECLARE_COMPLETION_ONSTACK(done);
 	int ret = num;

 	hisi_i2c_reset_xfer(ctlr);
 	ctlr->completion = &done;
 	ctlr->msg_num = num;
 	ctlr->msgs = msgs;

 	hisi_i2c_start_xfer(ctlr);

 	if (!wait_for_completion_timeout(ctlr->completion, adap->timeout)) {
 		hisi_i2c_disable_int(ctlr, HISI_I2C_INT_ALL);
 		synchronize_irq(ctlr->irq);
 		i2c_recover_bus(&ctlr->adapter);
 		dev_err(ctlr->dev, "bus transfer timeout\n");
 		ret = -EIO;
 	}

 	if (ctlr->xfer_err) {
 		hisi_i2c_handle_errors(ctlr);
 		ret = -EIO;
 	}

 	hisi_i2c_reset_xfer(ctlr);
 	ctlr->completion = NULL;

 	return ret;
 }

 static u32 hisi_i2c_functionality(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_EMUL;
 }

 static const struct i2c_algorithm hisi_i2c_algo = {
 	.master_xfer	= hisi_i2c_master_xfer,
 	.functionality	= hisi_i2c_functionality,
 };

 static int hisi_i2c_read_rx_fifo(struct hisi_i2c_controller *ctlr)
 {
 	struct i2c_msg *cur_msg;
 	u32 fifo_state;

 	while (ctlr->msg_rx_idx < ctlr->msg_num) {
 		cur_msg = ctlr->msgs + ctlr->msg_rx_idx;

 		if (!(cur_msg->flags & I2C_M_RD)) {
 			ctlr->msg_rx_idx++;
 			continue;
 		}

 		fifo_state = readl(ctlr->iobase + HISI_I2C_FIFO_STATE);
 		while (!(fifo_state & HISI_I2C_FIFO_STATE_RX_EMPTY) &&
 		       ctlr->buf_rx_idx < cur_msg->len) {
 			cur_msg->buf[ctlr->buf_rx_idx++] = readl(ctlr->iobase + HISI_I2C_RXDATA);
 			fifo_state = readl(ctlr->iobase + HISI_I2C_FIFO_STATE);
 		}

 		if (ctlr->buf_rx_idx == cur_msg->len) {
 			ctlr->buf_rx_idx = 0;
 			ctlr->msg_rx_idx++;
 		}

 		if (fifo_state & HISI_I2C_FIFO_STATE_RX_EMPTY)
 			break;
 	}

 	return 0;
 }

 static void hisi_i2c_xfer_msg(struct hisi_i2c_controller *ctlr)
 {
 	int max_write = HISI_I2C_TX_FIFO_DEPTH;
 	bool need_restart = false, last_msg;
 	struct i2c_msg *cur_msg;
 	u32 cmd, fifo_state;

 	while (ctlr->msg_tx_idx < ctlr->msg_num) {
 		cur_msg = ctlr->msgs + ctlr->msg_tx_idx;
 		last_msg = (ctlr->msg_tx_idx == ctlr->msg_num - 1);

 		/* Signal the SR bit when we start transferring a new message */
 		if (ctlr->msg_tx_idx && !ctlr->buf_tx_idx)
 			need_restart = true;

 		fifo_state = readl(ctlr->iobase + HISI_I2C_FIFO_STATE);
 		while (!(fifo_state & HISI_I2C_FIFO_STATE_TX_FULL) &&
 		       ctlr->buf_tx_idx < cur_msg->len && max_write) {
 			cmd = 0;

 			if (need_restart) {
 				cmd |= HISI_I2C_CMD_TXDATA_SR_EN;
 				need_restart = false;
 			}

 			/* Signal the STOP bit at the last frame of the last message */
 			if (ctlr->buf_tx_idx == cur_msg->len - 1 && last_msg)
 				cmd |= HISI_I2C_CMD_TXDATA_P_EN;

 			if (cur_msg->flags & I2C_M_RD)
 				cmd |= HISI_I2C_CMD_TXDATA_RW;
 			else
 				cmd |= FIELD_PREP(HISI_I2C_CMD_TXDATA_DATA,
 						  cur_msg->buf[ctlr->buf_tx_idx]);

 			writel(cmd, ctlr->iobase + HISI_I2C_CMD_TXDATA);
 			ctlr->buf_tx_idx++;
 			max_write--;

 			fifo_state = readl(ctlr->iobase + HISI_I2C_FIFO_STATE);
 		}

 		/* Update the transfer index after per message transfer is done. */
 		if (ctlr->buf_tx_idx == cur_msg->len) {
 			ctlr->buf_tx_idx = 0;
 			ctlr->msg_tx_idx++;
 		}

 		if ((fifo_state & HISI_I2C_FIFO_STATE_TX_FULL) ||
 		    max_write == 0)
 			break;
 	}
 }

 static irqreturn_t hisi_i2c_irq(int irq, void *context)
 {
 	struct hisi_i2c_controller *ctlr = context;
 	u32 int_stat;

 	int_stat = readl(ctlr->iobase + HISI_I2C_INT_MSTAT);
 	hisi_i2c_clear_int(ctlr, int_stat);
 	if (!(int_stat & HISI_I2C_INT_ALL))
 		return IRQ_NONE;

 	if (int_stat & HISI_I2C_INT_TX_EMPTY)
 		hisi_i2c_xfer_msg(ctlr);

 	if (int_stat & HISI_I2C_INT_ERR) {
 		ctlr->xfer_err = int_stat;
 		goto out;
 	}

 	/* Drain the rx fifo before finish the transfer */
 	if (int_stat & (HISI_I2C_INT_TRANS_CPLT | HISI_I2C_INT_RX_FULL))
 		hisi_i2c_read_rx_fifo(ctlr);

 out:
 	if (int_stat & HISI_I2C_INT_TRANS_CPLT || ctlr->xfer_err) {
 		hisi_i2c_disable_int(ctlr, HISI_I2C_INT_ALL);
 		hisi_i2c_clear_int(ctlr, HISI_I2C_INT_ALL);
 		complete(ctlr->completion);
 	}

 	return IRQ_HANDLED;
 }

 /*
  * Helper function for calculating and configuring the HIGH and LOW
  * periods of SCL clock. The caller will pass the ratio of the
  * counts (divide / divisor) according to the target speed mode,
  * and the target registers.
  */
 static void hisi_i2c_set_scl(struct hisi_i2c_controller *ctlr,
 			     u32 divide, u32 divisor,
 			     u32 reg_hcnt, u32 reg_lcnt)
 {
 	u32 total_cnt, t_scl_hcnt, t_scl_lcnt, scl_fall_cnt, scl_rise_cnt;
 	u32 scl_hcnt, scl_lcnt;

 	/* Total SCL clock cycles per speed period */
 	total_cnt = DIV_ROUND_UP_ULL(ctlr->clk_rate_khz * HZ_PER_KHZ, ctlr->t.bus_freq_hz);
 	/* Total HIGH level SCL clock cycles including edges */
 	t_scl_hcnt = DIV_ROUND_UP_ULL(total_cnt * divide, divisor);
 	/* Total LOW level SCL clock cycles including edges */
 	t_scl_lcnt = total_cnt - t_scl_hcnt;
 	/* Fall edge SCL clock cycles */
 	scl_fall_cnt = NSEC_TO_CYCLES(ctlr->t.scl_fall_ns, ctlr->clk_rate_khz);
 	/* Rise edge SCL clock cycles */
 	scl_rise_cnt = NSEC_TO_CYCLES(ctlr->t.scl_rise_ns, ctlr->clk_rate_khz);

 	/* Calculated HIGH and LOW periods of SCL clock */
 	scl_hcnt = t_scl_hcnt - ctlr->spk_len - 7 - scl_fall_cnt;
 	scl_lcnt = t_scl_lcnt - 1 - scl_rise_cnt;

 	writel(scl_hcnt, ctlr->iobase + reg_hcnt);
 	writel(scl_lcnt, ctlr->iobase + reg_lcnt);
 }

 static void hisi_i2c_configure_bus(struct hisi_i2c_controller *ctlr)
 {
 	u32 reg, sda_hold_cnt, speed_mode;

 	i2c_parse_fw_timings(ctlr->dev, &ctlr->t, true);
 	ctlr->spk_len = NSEC_TO_CYCLES(ctlr->t.digital_filter_width_ns, ctlr->clk_rate_khz);

 	switch (ctlr->t.bus_freq_hz) {
 	case I2C_MAX_FAST_MODE_FREQ:
 		speed_mode = HISI_I2C_FAST_SPEED_MODE;
 		hisi_i2c_set_scl(ctlr, 26, 76, HISI_I2C_FS_SCL_HCNT, HISI_I2C_FS_SCL_LCNT);
 		break;
 	case I2C_MAX_HIGH_SPEED_MODE_FREQ:
 		speed_mode = HISI_I2C_HIGH_SPEED_MODE;
 		hisi_i2c_set_scl(ctlr, 6, 22, HISI_I2C_HS_SCL_HCNT, HISI_I2C_HS_SCL_LCNT);
 		break;
 	case I2C_MAX_STANDARD_MODE_FREQ:
 	default:
 		speed_mode = HISI_I2C_STD_SPEED_MODE;

 		/* For default condition force the bus speed to standard mode. */
 		ctlr->t.bus_freq_hz = I2C_MAX_STANDARD_MODE_FREQ;
 		hisi_i2c_set_scl(ctlr, 40, 87, HISI_I2C_SS_SCL_HCNT, HISI_I2C_SS_SCL_LCNT);
 		break;
 	}

 	reg = readl(ctlr->iobase + HISI_I2C_FRAME_CTRL);
 	reg &= ~HISI_I2C_FRAME_CTRL_SPEED_MODE;
 	reg |= FIELD_PREP(HISI_I2C_FRAME_CTRL_SPEED_MODE, speed_mode);
 	writel(reg, ctlr->iobase + HISI_I2C_FRAME_CTRL);

 	sda_hold_cnt = NSEC_TO_CYCLES(ctlr->t.sda_hold_ns, ctlr->clk_rate_khz);

 	reg = FIELD_PREP(HISI_I2C_SDA_HOLD_TX, sda_hold_cnt);
 	writel(reg, ctlr->iobase + HISI_I2C_SDA_HOLD);

 	writel(ctlr->spk_len, ctlr->iobase + HISI_I2C_FS_SPK_LEN);

 	reg = FIELD_PREP(HISI_I2C_FIFO_RX_AF_THRESH, HISI_I2C_RX_F_AF_THRESH);
 	reg |= FIELD_PREP(HISI_I2C_FIFO_TX_AE_THRESH, HISI_I2C_TX_F_AE_THRESH);
 	writel(reg, ctlr->iobase + HISI_I2C_FIFO_CTRL);
 }

 static int hisi_i2c_probe(struct platform_device *pdev)
 {
 	struct hisi_i2c_controller *ctlr;
 	struct device *dev = &pdev->dev;
 	struct i2c_adapter *adapter;
 	u64 clk_rate_hz;
 	u32 hw_version;
 	int ret;

 	ctlr = devm_kzalloc(dev, sizeof(*ctlr), GFP_KERNEL);
 	if (!ctlr)
 		return -ENOMEM;

 	ctlr->iobase = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(ctlr->iobase))
 		return PTR_ERR(ctlr->iobase);

 	ctlr->irq = platform_get_irq(pdev, 0);
 	if (ctlr->irq < 0)
 		return ctlr->irq;

 	ctlr->dev = dev;

 	hisi_i2c_disable_int(ctlr, HISI_I2C_INT_ALL);

 	ret = devm_request_irq(dev, ctlr->irq, hisi_i2c_irq, 0, "hisi-i2c", ctlr);
 	if (ret) {
 		dev_err(dev, "failed to request irq handler, ret = %d\n", ret);
 		return ret;
 	}

 	ctlr->clk = devm_clk_get_optional_enabled(&pdev->dev, NULL);
 	if (IS_ERR_OR_NULL(ctlr->clk)) {
 		ret = device_property_read_u64(dev, "clk_rate", &clk_rate_hz);
 		if (ret) {
 			dev_err(dev, "failed to get clock frequency, ret = %d\n", ret);
 			return ret;
 		}
 	} else {
 		clk_rate_hz = clk_get_rate(ctlr->clk);
 	}

 	ctlr->clk_rate_khz = DIV_ROUND_UP_ULL(clk_rate_hz, HZ_PER_KHZ);

 	hisi_i2c_configure_bus(ctlr);

 	adapter = &ctlr->adapter;
 	snprintf(adapter->name, sizeof(adapter->name),
 		 "HiSilicon I2C Controller %s", dev_name(dev));
 	adapter->owner = THIS_MODULE;
 	adapter->algo = &hisi_i2c_algo;
 	adapter->dev.parent = dev;
 	i2c_set_adapdata(adapter, ctlr);

 	ret = devm_i2c_add_adapter(dev, adapter);
 	if (ret)
 		return ret;

 	hw_version = readl(ctlr->iobase + HISI_I2C_VERSION);
 	dev_info(ctlr->dev, "speed mode is %s. hw version 0x%x\n",
 		 i2c_freq_mode_string(ctlr->t.bus_freq_hz), hw_version);

 	return 0;
 }

 static const struct acpi_device_id hisi_i2c_acpi_ids[] = {
 	{ "HISI03D1", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(acpi, hisi_i2c_acpi_ids);

 static const struct of_device_id hisi_i2c_dts_ids[] = {
 	{ .compatible = "hisilicon,ascend910-i2c", },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, hisi_i2c_dts_ids);

 static struct platform_driver hisi_i2c_driver = {
 	.probe		= hisi_i2c_probe,
 	.driver		= {
 		.name	= "hisi-i2c",
 		.acpi_match_table = hisi_i2c_acpi_ids,
 		.of_match_table = hisi_i2c_dts_ids,
 	},
 };
 module_platform_driver(hisi_i2c_driver);

 MODULE_AUTHOR("Yicong Yang <yangyicong@hisilicon.com>");
 MODULE_DESCRIPTION("HiSilicon I2C Controller Driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* HiSilicon I2C Controller Driver for Kunpeng SoC
	*
	* Copyright (c) 2021 HiSilicon Technologies Co., Ltd.
	*/

	#include <linux/bits.h>
	#include <linux/bitfield.h>
	#include <linux/clk.h>
	#include <linux/completion.h>
	#include <linux/i2c.h>
	#include <linux/interrupt.h>
	#include <linux/io.h>
	#include <linux/module.h>
	#include <linux/mod_devicetable.h>
	#include <linux/platform_device.h>
	#include <linux/property.h>
	#include <linux/units.h>

	#define HISI_I2C_FRAME_CTRL 0x0000
	#define HISI_I2C_FRAME_CTRL_SPEED_MODE GENMASK(1, 0)
	#define HISI_I2C_FRAME_CTRL_ADDR_TEN BIT(2)
	#define HISI_I2C_SLV_ADDR 0x0004
	#define HISI_I2C_SLV_ADDR_VAL GENMASK(9, 0)
	#define HISI_I2C_SLV_ADDR_GC_S_MODE BIT(10)
	#define HISI_I2C_SLV_ADDR_GC_S_EN BIT(11)
	#define HISI_I2C_CMD_TXDATA 0x0008
	#define HISI_I2C_CMD_TXDATA_DATA GENMASK(7, 0)
	#define HISI_I2C_CMD_TXDATA_RW BIT(8)
	#define HISI_I2C_CMD_TXDATA_P_EN BIT(9)
	#define HISI_I2C_CMD_TXDATA_SR_EN BIT(10)
	#define HISI_I2C_RXDATA 0x000c
	#define HISI_I2C_RXDATA_DATA GENMASK(7, 0)
	#define HISI_I2C_SS_SCL_HCNT 0x0010
	#define HISI_I2C_SS_SCL_LCNT 0x0014
	#define HISI_I2C_FS_SCL_HCNT 0x0018
	#define HISI_I2C_FS_SCL_LCNT 0x001c
	#define HISI_I2C_HS_SCL_HCNT 0x0020
	#define HISI_I2C_HS_SCL_LCNT 0x0024
	#define HISI_I2C_FIFO_CTRL 0x0028
	#define HISI_I2C_FIFO_RX_CLR BIT(0)
	#define HISI_I2C_FIFO_TX_CLR BIT(1)
	#define HISI_I2C_FIFO_RX_AF_THRESH GENMASK(7, 2)
	#define HISI_I2C_FIFO_TX_AE_THRESH GENMASK(13, 8)
	#define HISI_I2C_FIFO_STATE 0x002c
	#define HISI_I2C_FIFO_STATE_RX_RERR BIT(0)
	#define HISI_I2C_FIFO_STATE_RX_WERR BIT(1)
	#define HISI_I2C_FIFO_STATE_RX_EMPTY BIT(3)
	#define HISI_I2C_FIFO_STATE_TX_RERR BIT(6)
	#define HISI_I2C_FIFO_STATE_TX_WERR BIT(7)
	#define HISI_I2C_FIFO_STATE_TX_FULL BIT(11)
	#define HISI_I2C_SDA_HOLD 0x0030
	#define HISI_I2C_SDA_HOLD_TX GENMASK(15, 0)
	#define HISI_I2C_SDA_HOLD_RX GENMASK(23, 16)
	#define HISI_I2C_FS_SPK_LEN 0x0038
	#define HISI_I2C_FS_SPK_LEN_CNT GENMASK(7, 0)
	#define HISI_I2C_HS_SPK_LEN 0x003c
	#define HISI_I2C_HS_SPK_LEN_CNT GENMASK(7, 0)
	#define HISI_I2C_INT_MSTAT 0x0044
	#define HISI_I2C_INT_CLR 0x0048
	#define HISI_I2C_INT_MASK 0x004C
	#define HISI_I2C_TRANS_STATE 0x0050
	#define HISI_I2C_TRANS_ERR 0x0054
	#define HISI_I2C_VERSION 0x0058

	#define HISI_I2C_INT_ALL GENMASK(4, 0)
	#define HISI_I2C_INT_TRANS_CPLT BIT(0)
	#define HISI_I2C_INT_TRANS_ERR BIT(1)
	#define HISI_I2C_INT_FIFO_ERR BIT(2)
	#define HISI_I2C_INT_RX_FULL BIT(3)
	#define HISI_I2C_INT_TX_EMPTY BIT(4)
	#define HISI_I2C_INT_ERR \
	(HISI_I2C_INT_TRANS_ERR \| HISI_I2C_INT_FIFO_ERR)

	#define HISI_I2C_STD_SPEED_MODE 0
	#define HISI_I2C_FAST_SPEED_MODE 1
	#define HISI_I2C_HIGH_SPEED_MODE 2

	#define HISI_I2C_TX_FIFO_DEPTH 64
	#define HISI_I2C_RX_FIFO_DEPTH 64
	#define HISI_I2C_TX_F_AE_THRESH 1
	#define HISI_I2C_RX_F_AF_THRESH 60

	#define NSEC_TO_CYCLES(ns, clk_rate_khz) \
	DIV_ROUND_UP_ULL((clk_rate_khz) * (ns), NSEC_PER_MSEC)

	struct hisi_i2c_controller {
	struct i2c_adapter adapter;
	void __iomem *iobase;
	struct device *dev;
	struct clk *clk;
	int irq;

	/* Intermediates for recording the transfer process */
	struct completion *completion;
	struct i2c_msg *msgs;
	int msg_num;
	int msg_tx_idx;
	int buf_tx_idx;
	int msg_rx_idx;
	int buf_rx_idx;
	u16 tar_addr;
	u32 xfer_err;

	/* I2C bus configuration */
	struct i2c_timings t;
	u32 clk_rate_khz;
	u32 spk_len;
	};

	static void hisi_i2c_enable_int(struct hisi_i2c_controller *ctlr, u32 mask)
	{
	writel_relaxed(mask, ctlr->iobase + HISI_I2C_INT_MASK);
	}

	static void hisi_i2c_disable_int(struct hisi_i2c_controller *ctlr, u32 mask)
	{
	writel_relaxed((~mask) & HISI_I2C_INT_ALL, ctlr->iobase + HISI_I2C_INT_MASK);
	}

	static void hisi_i2c_clear_int(struct hisi_i2c_controller *ctlr, u32 mask)
	{
	writel_relaxed(mask, ctlr->iobase + HISI_I2C_INT_CLR);
	}

	static void hisi_i2c_handle_errors(struct hisi_i2c_controller *ctlr)
	{
	u32 int_err = ctlr->xfer_err, reg;

	if (int_err & HISI_I2C_INT_FIFO_ERR) {
	reg = readl(ctlr->iobase + HISI_I2C_FIFO_STATE);

	if (reg & HISI_I2C_FIFO_STATE_RX_RERR)
	dev_err(ctlr->dev, "rx fifo error read\n");

	if (reg & HISI_I2C_FIFO_STATE_RX_WERR)
	dev_err(ctlr->dev, "rx fifo error write\n");

	if (reg & HISI_I2C_FIFO_STATE_TX_RERR)
	dev_err(ctlr->dev, "tx fifo error read\n");

	if (reg & HISI_I2C_FIFO_STATE_TX_WERR)
	dev_err(ctlr->dev, "tx fifo error write\n");
	}
	}

	static int hisi_i2c_start_xfer(struct hisi_i2c_controller *ctlr)
	{
	struct i2c_msg *msg = ctlr->msgs;
	u32 reg;

	reg = readl(ctlr->iobase + HISI_I2C_FRAME_CTRL);
	reg &= ~HISI_I2C_FRAME_CTRL_ADDR_TEN;
	if (msg->flags & I2C_M_TEN)
	reg \|= HISI_I2C_FRAME_CTRL_ADDR_TEN;
	writel(reg, ctlr->iobase + HISI_I2C_FRAME_CTRL);

	reg = readl(ctlr->iobase + HISI_I2C_SLV_ADDR);
	reg &= ~HISI_I2C_SLV_ADDR_VAL;
	reg \|= FIELD_PREP(HISI_I2C_SLV_ADDR_VAL, msg->addr);
	writel(reg, ctlr->iobase + HISI_I2C_SLV_ADDR);

	reg = readl(ctlr->iobase + HISI_I2C_FIFO_CTRL);
	reg \|= HISI_I2C_FIFO_RX_CLR \| HISI_I2C_FIFO_TX_CLR;
	writel(reg, ctlr->iobase + HISI_I2C_FIFO_CTRL);
	reg &= ~(HISI_I2C_FIFO_RX_CLR \| HISI_I2C_FIFO_TX_CLR);
	writel(reg, ctlr->iobase + HISI_I2C_FIFO_CTRL);

	hisi_i2c_clear_int(ctlr, HISI_I2C_INT_ALL);
	hisi_i2c_enable_int(ctlr, HISI_I2C_INT_ALL);

	return 0;
	}

	static void hisi_i2c_reset_xfer(struct hisi_i2c_controller *ctlr)
	{
	ctlr->msg_num = 0;
	ctlr->xfer_err = 0;
	ctlr->msg_tx_idx = 0;
	ctlr->msg_rx_idx = 0;
	ctlr->buf_tx_idx = 0;
	ctlr->buf_rx_idx = 0;
	}

	/*
	* Initialize the transfer information and start the I2C bus transfer.
	* We only configure the transfer and do some pre/post works here, and
	* wait for the transfer done. The major transfer process is performed
	* in the IRQ handler.
	*/
	static int hisi_i2c_master_xfer(struct i2c_adapter adap, struct i2c_msg msgs,
	int num)
	{
	struct hisi_i2c_controller *ctlr = i2c_get_adapdata(adap);
	DECLARE_COMPLETION_ONSTACK(done);
	int ret = num;

	hisi_i2c_reset_xfer(ctlr);
	ctlr->completion = &done;
	ctlr->msg_num = num;
	ctlr->msgs = msgs;

	hisi_i2c_start_xfer(ctlr);

	if (!wait_for_completion_timeout(ctlr->completion, adap->timeout)) {
	hisi_i2c_disable_int(ctlr, HISI_I2C_INT_ALL);
	synchronize_irq(ctlr->irq);
	i2c_recover_bus(&ctlr->adapter);
	dev_err(ctlr->dev, "bus transfer timeout\n");
	ret = -EIO;
	}

	if (ctlr->xfer_err) {
	hisi_i2c_handle_errors(ctlr);
	ret = -EIO;
	}

	hisi_i2c_reset_xfer(ctlr);
	ctlr->completion = NULL;

	return ret;
	}

	static u32 hisi_i2c_functionality(struct i2c_adapter *adap)
	{
	return I2C_FUNC_I2C \| I2C_FUNC_10BIT_ADDR \| I2C_FUNC_SMBUS_EMUL;
	}

	static const struct i2c_algorithm hisi_i2c_algo = {
	.master_xfer = hisi_i2c_master_xfer,
	.functionality = hisi_i2c_functionality,
	};

	static int hisi_i2c_read_rx_fifo(struct hisi_i2c_controller *ctlr)
	{
	struct i2c_msg *cur_msg;
	u32 fifo_state;

	while (ctlr->msg_rx_idx < ctlr->msg_num) {
	cur_msg = ctlr->msgs + ctlr->msg_rx_idx;

	if (!(cur_msg->flags & I2C_M_RD)) {
	ctlr->msg_rx_idx++;
	continue;
	}

	fifo_state = readl(ctlr->iobase + HISI_I2C_FIFO_STATE);
	while (!(fifo_state & HISI_I2C_FIFO_STATE_RX_EMPTY) &&
	ctlr->buf_rx_idx < cur_msg->len) {
	cur_msg->buf[ctlr->buf_rx_idx++] = readl(ctlr->iobase + HISI_I2C_RXDATA);
	fifo_state = readl(ctlr->iobase + HISI_I2C_FIFO_STATE);
	}

	if (ctlr->buf_rx_idx == cur_msg->len) {
	ctlr->buf_rx_idx = 0;
	ctlr->msg_rx_idx++;
	}

	if (fifo_state & HISI_I2C_FIFO_STATE_RX_EMPTY)
	break;
	}

	return 0;
	}

	static void hisi_i2c_xfer_msg(struct hisi_i2c_controller *ctlr)
	{
	int max_write = HISI_I2C_TX_FIFO_DEPTH;
	bool need_restart = false, last_msg;
	struct i2c_msg *cur_msg;
	u32 cmd, fifo_state;

	while (ctlr->msg_tx_idx < ctlr->msg_num) {
	cur_msg = ctlr->msgs + ctlr->msg_tx_idx;
	last_msg = (ctlr->msg_tx_idx == ctlr->msg_num - 1);

	/* Signal the SR bit when we start transferring a new message */
	if (ctlr->msg_tx_idx && !ctlr->buf_tx_idx)
	need_restart = true;

	fifo_state = readl(ctlr->iobase + HISI_I2C_FIFO_STATE);
	while (!(fifo_state & HISI_I2C_FIFO_STATE_TX_FULL) &&
	ctlr->buf_tx_idx < cur_msg->len && max_write) {
	cmd = 0;

	if (need_restart) {
	cmd \|= HISI_I2C_CMD_TXDATA_SR_EN;
	need_restart = false;
	}

	/* Signal the STOP bit at the last frame of the last message */
	if (ctlr->buf_tx_idx == cur_msg->len - 1 && last_msg)
	cmd \|= HISI_I2C_CMD_TXDATA_P_EN;

	if (cur_msg->flags & I2C_M_RD)
	cmd \|= HISI_I2C_CMD_TXDATA_RW;
	else
	cmd \|= FIELD_PREP(HISI_I2C_CMD_TXDATA_DATA,
	cur_msg->buf[ctlr->buf_tx_idx]);

	writel(cmd, ctlr->iobase + HISI_I2C_CMD_TXDATA);
	ctlr->buf_tx_idx++;
	max_write--;

	fifo_state = readl(ctlr->iobase + HISI_I2C_FIFO_STATE);
	}

	/* Update the transfer index after per message transfer is done. */
	if (ctlr->buf_tx_idx == cur_msg->len) {
	ctlr->buf_tx_idx = 0;
	ctlr->msg_tx_idx++;
	}

	if ((fifo_state & HISI_I2C_FIFO_STATE_TX_FULL) \|\|
	max_write == 0)
	break;
	}
	}

	static irqreturn_t hisi_i2c_irq(int irq, void *context)
	{
	struct hisi_i2c_controller *ctlr = context;
	u32 int_stat;

	int_stat = readl(ctlr->iobase + HISI_I2C_INT_MSTAT);
	hisi_i2c_clear_int(ctlr, int_stat);
	if (!(int_stat & HISI_I2C_INT_ALL))
	return IRQ_NONE;

	if (int_stat & HISI_I2C_INT_TX_EMPTY)
	hisi_i2c_xfer_msg(ctlr);

	if (int_stat & HISI_I2C_INT_ERR) {
	ctlr->xfer_err = int_stat;
	goto out;
	}

	/* Drain the rx fifo before finish the transfer */
	if (int_stat & (HISI_I2C_INT_TRANS_CPLT \| HISI_I2C_INT_RX_FULL))
	hisi_i2c_read_rx_fifo(ctlr);

	out:
	if (int_stat & HISI_I2C_INT_TRANS_CPLT \|\| ctlr->xfer_err) {
	hisi_i2c_disable_int(ctlr, HISI_I2C_INT_ALL);
	hisi_i2c_clear_int(ctlr, HISI_I2C_INT_ALL);
	complete(ctlr->completion);
	}

	return IRQ_HANDLED;
	}

	/*
	* Helper function for calculating and configuring the HIGH and LOW
	* periods of SCL clock. The caller will pass the ratio of the
	* counts (divide / divisor) according to the target speed mode,
	* and the target registers.
	*/
	static void hisi_i2c_set_scl(struct hisi_i2c_controller *ctlr,
	u32 divide, u32 divisor,
	u32 reg_hcnt, u32 reg_lcnt)
	{
	u32 total_cnt, t_scl_hcnt, t_scl_lcnt, scl_fall_cnt, scl_rise_cnt;
	u32 scl_hcnt, scl_lcnt;

	/* Total SCL clock cycles per speed period */
	total_cnt = DIV_ROUND_UP_ULL(ctlr->clk_rate_khz * HZ_PER_KHZ, ctlr->t.bus_freq_hz);
	/* Total HIGH level SCL clock cycles including edges */
	t_scl_hcnt = DIV_ROUND_UP_ULL(total_cnt * divide, divisor);
	/* Total LOW level SCL clock cycles including edges */
	t_scl_lcnt = total_cnt - t_scl_hcnt;
	/* Fall edge SCL clock cycles */
	scl_fall_cnt = NSEC_TO_CYCLES(ctlr->t.scl_fall_ns, ctlr->clk_rate_khz);
	/* Rise edge SCL clock cycles */
	scl_rise_cnt = NSEC_TO_CYCLES(ctlr->t.scl_rise_ns, ctlr->clk_rate_khz);

	/* Calculated HIGH and LOW periods of SCL clock */
	scl_hcnt = t_scl_hcnt - ctlr->spk_len - 7 - scl_fall_cnt;
	scl_lcnt = t_scl_lcnt - 1 - scl_rise_cnt;

	writel(scl_hcnt, ctlr->iobase + reg_hcnt);
	writel(scl_lcnt, ctlr->iobase + reg_lcnt);
	}

	static void hisi_i2c_configure_bus(struct hisi_i2c_controller *ctlr)
	{
	u32 reg, sda_hold_cnt, speed_mode;

	i2c_parse_fw_timings(ctlr->dev, &ctlr->t, true);
	ctlr->spk_len = NSEC_TO_CYCLES(ctlr->t.digital_filter_width_ns, ctlr->clk_rate_khz);

	switch (ctlr->t.bus_freq_hz) {
	case I2C_MAX_FAST_MODE_FREQ:
	speed_mode = HISI_I2C_FAST_SPEED_MODE;
	hisi_i2c_set_scl(ctlr, 26, 76, HISI_I2C_FS_SCL_HCNT, HISI_I2C_FS_SCL_LCNT);
	break;
	case I2C_MAX_HIGH_SPEED_MODE_FREQ:
	speed_mode = HISI_I2C_HIGH_SPEED_MODE;
	hisi_i2c_set_scl(ctlr, 6, 22, HISI_I2C_HS_SCL_HCNT, HISI_I2C_HS_SCL_LCNT);
	break;
	case I2C_MAX_STANDARD_MODE_FREQ:
	default:
	speed_mode = HISI_I2C_STD_SPEED_MODE;

	/* For default condition force the bus speed to standard mode. */
	ctlr->t.bus_freq_hz = I2C_MAX_STANDARD_MODE_FREQ;
	hisi_i2c_set_scl(ctlr, 40, 87, HISI_I2C_SS_SCL_HCNT, HISI_I2C_SS_SCL_LCNT);
	break;
	}

	reg = readl(ctlr->iobase + HISI_I2C_FRAME_CTRL);
	reg &= ~HISI_I2C_FRAME_CTRL_SPEED_MODE;
	reg \|= FIELD_PREP(HISI_I2C_FRAME_CTRL_SPEED_MODE, speed_mode);
	writel(reg, ctlr->iobase + HISI_I2C_FRAME_CTRL);

	sda_hold_cnt = NSEC_TO_CYCLES(ctlr->t.sda_hold_ns, ctlr->clk_rate_khz);

	reg = FIELD_PREP(HISI_I2C_SDA_HOLD_TX, sda_hold_cnt);
	writel(reg, ctlr->iobase + HISI_I2C_SDA_HOLD);

	writel(ctlr->spk_len, ctlr->iobase + HISI_I2C_FS_SPK_LEN);

	reg = FIELD_PREP(HISI_I2C_FIFO_RX_AF_THRESH, HISI_I2C_RX_F_AF_THRESH);
	reg \|= FIELD_PREP(HISI_I2C_FIFO_TX_AE_THRESH, HISI_I2C_TX_F_AE_THRESH);
	writel(reg, ctlr->iobase + HISI_I2C_FIFO_CTRL);
	}

	static int hisi_i2c_probe(struct platform_device *pdev)
	{
	struct hisi_i2c_controller *ctlr;
	struct device *dev = &pdev->dev;
	struct i2c_adapter *adapter;
	u64 clk_rate_hz;
	u32 hw_version;
	int ret;

	ctlr = devm_kzalloc(dev, sizeof(*ctlr), GFP_KERNEL);
	if (!ctlr)
	return -ENOMEM;

	ctlr->iobase = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(ctlr->iobase))
	return PTR_ERR(ctlr->iobase);

	ctlr->irq = platform_get_irq(pdev, 0);
	if (ctlr->irq < 0)
	return ctlr->irq;

	ctlr->dev = dev;

	hisi_i2c_disable_int(ctlr, HISI_I2C_INT_ALL);

	ret = devm_request_irq(dev, ctlr->irq, hisi_i2c_irq, 0, "hisi-i2c", ctlr);
	if (ret) {
	dev_err(dev, "failed to request irq handler, ret = %d\n", ret);
	return ret;
	}

	ctlr->clk = devm_clk_get_optional_enabled(&pdev->dev, NULL);
	if (IS_ERR_OR_NULL(ctlr->clk)) {
	ret = device_property_read_u64(dev, "clk_rate", &clk_rate_hz);
	if (ret) {
	dev_err(dev, "failed to get clock frequency, ret = %d\n", ret);
	return ret;
	}
	} else {
	clk_rate_hz = clk_get_rate(ctlr->clk);
	}

	ctlr->clk_rate_khz = DIV_ROUND_UP_ULL(clk_rate_hz, HZ_PER_KHZ);

	hisi_i2c_configure_bus(ctlr);

	adapter = &ctlr->adapter;
	snprintf(adapter->name, sizeof(adapter->name),
	"HiSilicon I2C Controller %s", dev_name(dev));
	adapter->owner = THIS_MODULE;
	adapter->algo = &hisi_i2c_algo;
	adapter->dev.parent = dev;
	i2c_set_adapdata(adapter, ctlr);

	ret = devm_i2c_add_adapter(dev, adapter);
	if (ret)
	return ret;

	hw_version = readl(ctlr->iobase + HISI_I2C_VERSION);
	dev_info(ctlr->dev, "speed mode is %s. hw version 0x%x\n",
	i2c_freq_mode_string(ctlr->t.bus_freq_hz), hw_version);

	return 0;
	}

	static const struct acpi_device_id hisi_i2c_acpi_ids[] = {
	{ "HISI03D1", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(acpi, hisi_i2c_acpi_ids);

	static const struct of_device_id hisi_i2c_dts_ids[] = {
	{ .compatible = "hisilicon,ascend910-i2c", },
	{ }
	};
	MODULE_DEVICE_TABLE(of, hisi_i2c_dts_ids);

	static struct platform_driver hisi_i2c_driver = {
	.probe = hisi_i2c_probe,
	.driver = {
	.name = "hisi-i2c",
	.acpi_match_table = hisi_i2c_acpi_ids,
	.of_match_table = hisi_i2c_dts_ids,
	},
	};
	module_platform_driver(hisi_i2c_driver);

	MODULE_AUTHOR("Yicong Yang <yangyicong@hisilicon.com>");
	MODULE_DESCRIPTION("HiSilicon I2C Controller Driver");
	MODULE_LICENSE("GPL");