Date: Wed, 16 Oct 2013 17:14:19 +0200
From: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
To: Maxime COQUELIN <maxime.coquelin@st.com>
Cc: Wolfram Sang <wsa@the-dreams.de>, srinivas.kandagatla@st.com,
        Rob Herring <rob.herring@calxeda.com>, Pawel Moll <pawel.moll@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Stephen Warren <swarren@wwwdotorg.org>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Rob Landley <rob@landley.net>, Russell King <linux@arm.linux.org.uk>,
        Grant Likely <grant.likely@linaro.org>, devicetree@vger.kernel.org,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-i2c@vger.kernel.org,
        stuart.menefy@st.com, Lee Jones <lee.jones@linaro.org>,
        stephen.gallimore@st.com, gabriel.fernandez@st.com
Subject: Re: [PATCH v5 1/4] i2c: busses: i2c-st: Add ST I2C controller
Message-ID: <20131016151419.GA14104@ns203013.ovh.net>
References: <1381754813-4679-1-git-send-email-maxime.coquelin@st.com>
 <1381754813-4679-2-git-send-email-maxime.coquelin@st.com>
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> +/**
> + * struct st_i2c_dev - private data of the controller
> + * @adap: I2C adapter for this controller
> + * @dev: device for this controller
> + * @base: virtual memory area
> + * @complete: completion of I2C message
> + * @irq: interrupt line for th controller
> + * @clk: hw ssc block clock
> + * @mode: I2C mode of the controller. Standard or Fast only supported
> + * @deglitch: Anti-glitch filters parameters
> + * @client: I2C transfert information
> + * @busy: I2C transfer on-going
> + */
> +struct st_i2c_dev {
> +	struct i2c_adapter	adap;
> +	struct device		*dev;
> +	void __iomem		*base;
> +	struct completion	complete;
> +	int			irq;
> +	struct clk		*clk;
> +	int			mode;
> +	struct st_i2c_deglitch	deglitch;
> +	struct st_i2c_client	client;
> +	bool			busy;
> +};
> +
> +static inline void st_i2c_set_bits(void __iomem *reg, u32 mask)
> +{
> +	writel(readl(reg) | mask, reg);
> +}
> +
> +static inline void st_i2c_clr_bits(void __iomem *reg, u32 mask)
> +{
> +	writel(readl(reg) & ~mask, reg);
use set_bit api and use relaxed version
> +}
> +
> +/* From I2C Specifications v0.5 */
> +static struct st_i2c_timings i2c_timings[] = {
> +	[I2C_MODE_STANDARD] = {
> +		.rate			= 100000,
> +		.rep_start_hold		= 4000,
> +		.rep_start_setup	= 4700,
> +		.start_hold		= 4000,
> +		.data_setup_time	= 250,
> +		.stop_setup_time	= 4000,
> +		.bus_free_time		= 4700,
> +	},
> +	[I2C_MODE_FAST] = {
> +		.rate			= 400000,
> +		.rep_start_hold		= 600,
> +		.rep_start_setup	= 600,
> +		.start_hold		= 600,
> +		.data_setup_time	= 100,
> +		.stop_setup_time	= 600,
> +		.bus_free_time		= 1300,
> +	},
> +};

so how do you plane to support other rate that 100k and 400k?
> +
> +static void st_i2c_flush_rx_fifo(struct st_i2c_dev *i2c_dev)
> +{
> +	int count, i;
> +
> +	/*
> +	 * Counter only counts up to 7 but fifo size is 8...
> +	 * When fifo is full, counter is 0 and RIR bit of status register is
> +	 * set
> +	 */
> +	if (readl(i2c_dev->base + SSC_STA) & SSC_STA_RIR)
> +		count = SSC_RXFIFO_SIZE;
> +	else
> +		count = readl(i2c_dev->base + SSC_RX_FSTAT) &
> +			SSC_RX_FSTAT_STATUS;
> +
> +	for (i = 0; i < count; i++)
> +		readl(i2c_dev->base + SSC_RBUF);
use readsl

use relaxed version as much as possible

> +}
> +
> +static void st_i2c_soft_reset(struct st_i2c_dev *i2c_dev)
> +{
> +	/*
> +	 * FIFO needs to be emptied before reseting the IP,
> +	 * else the controller raises a BUSY error.
> +	 */
> +	st_i2c_flush_rx_fifo(i2c_dev);
> +
> +	st_i2c_set_bits(i2c_dev->base + SSC_CTL, SSC_CTL_SR);
> +	st_i2c_clr_bits(i2c_dev->base + SSC_CTL, SSC_CTL_SR);
> +}
> +
> +/**
> + * st_i2c_hw_config() - Prepare SSC block, calculate and apply tuning timings
> + * @i2c_dev: Controller's private data
> + */
> +static void st_i2c_hw_config(struct st_i2c_dev *i2c_dev)
> +{
> +	unsigned long rate;
> +	u32 val, ns_per_clk;
> +	struct st_i2c_timings *t = &i2c_timings[i2c_dev->mode];
> +
> +	st_i2c_soft_reset(i2c_dev);
> +
> +	val = SSC_CLR_REPSTRT | SSC_CLR_NACK | SSC_CLR_SSCARBL |
> +		SSC_CLR_SSCAAS | SSC_CLR_SSCSTOP;
> +	writel(val, i2c_dev->base + SSC_CLR);
> +
> +	/* SSC Control register setup */
> +	val = SSC_CTL_PO | SSC_CTL_PH | SSC_CTL_HB | SSC_CTL_DATA_WIDTH_9;
> +	writel(val, i2c_dev->base + SSC_CTL);
> +
> +	rate = clk_get_rate(i2c_dev->clk);
> +	ns_per_clk = 1000000000 / rate;
> +
> +	/* Baudrate */
> +	val = rate / (2 * t->rate);
> +	writel(val, i2c_dev->base + SSC_BRG);
> +
> +	/* Pre-scaler baudrate */
> +	writel(1, i2c_dev->base + SSC_PRE_SCALER_BRG);
> +
> +	/* Enable I2C mode */
> +	writel(SSC_I2C_I2CM, i2c_dev->base + SSC_I2C);
> +
> +	/* Repeated start hold time */
> +	val = t->rep_start_hold / ns_per_clk;
> +	writel(val, i2c_dev->base + SSC_REP_START_HOLD);
> +
> +	/* Repeated start set up time */
> +	val = t->rep_start_setup / ns_per_clk;
> +	writel(val, i2c_dev->base + SSC_REP_START_SETUP);
> +
> +	/* Start hold time */
> +	val = t->start_hold / ns_per_clk;
> +	writel(val, i2c_dev->base + SSC_START_HOLD);
> +
> +	/* Data set up time */
> +	val = t->data_setup_time / ns_per_clk;
> +	writel(val, i2c_dev->base + SSC_DATA_SETUP);
> +
> +	/* Stop set up time */
> +	val = t->stop_setup_time / ns_per_clk;
> +	writel(val, i2c_dev->base + SSC_STOP_SETUP);
> +
> +	/* Bus free time */
> +	val = t->bus_free_time / ns_per_clk;
> +	writel(val, i2c_dev->base + SSC_BUS_FREE);
> +
> +	/* Prescalers set up */
> +	val = rate / 10000000;
> +	writel(val, i2c_dev->base + SSC_PRSCALER);
> +	writel(val, i2c_dev->base + SSC_PRSCALER_DATAOUT);
> +
> +	/* Noise suppression witdh */
> +	val = i2c_dev->deglitch.scl_min_width_us * rate / 100000000;
> +	writel(val, i2c_dev->base + SSC_NOISE_SUPP_WIDTH);
> +
> +	/* Noise suppression max output data delay width */
> +	val = i2c_dev->deglitch.sda_min_width_us * rate / 100000000;
> +	writel(val, i2c_dev->base + SSC_NOISE_SUPP_WIDTH_DATAOUT);
> +}
> +
> +static int st_i2c_wait_free_bus(struct st_i2c_dev *i2c_dev)
> +{
> +	u32 sta;
> +	int i;
> +
> +	for (i = 0; i < 10; i++) {
> +		sta = readl(i2c_dev->base + SSC_STA);
> +		if (!(sta & SSC_STA_BUSY))
> +			return 0;
> +
> +		usleep_range(2000, 4000);
can not use interrupt?
> +	}
> +
> +	dev_err(i2c_dev->dev, "bus not free (status = 0x%08x)\n", sta);
> +
> +	return -EBUSY;
> +}
> +
> +/**
> + * st_i2c_write_tx_fifo() - Write a byte in the Tx FIFO
> + * @i2c_dev: Controller's private data
> + * @byte: Data to write in the Tx FIFO
> + */
> +static inline void st_i2c_write_tx_fifo(struct st_i2c_dev *i2c_dev, u8 byte)
> +{
> +	u16 tbuf = byte << 1;
> +
> +	writel(tbuf | 1, i2c_dev->base + SSC_TBUF);
> +}
> +
> +/**
> + * st_i2c_wr_fill_tx_fifo() - Fill the Tx FIFO in write mode
> + * @i2c_dev: Controller's private data
> + *
> + * This functions fills the Tx FIFO with I2C transfert buffer when
> + * in write mode.
> + */
> +static void st_i2c_wr_fill_tx_fifo(struct st_i2c_dev *i2c_dev)
> +{
> +	struct st_i2c_client *c = &i2c_dev->client;
> +	u32 tx_fstat, sta;
> +	int i;
> +
> +	sta = readl(i2c_dev->base + SSC_STA);
> +	if (sta & SSC_STA_TX_FIFO_FULL)
> +		return;
> +
> +	tx_fstat = readl(i2c_dev->base + SSC_TX_FSTAT) & SSC_TX_FSTAT_STATUS;
> +
> +	if (c->count < (SSC_TXFIFO_SIZE - tx_fstat))
> +		i = c->count;
> +	else
> +		i = SSC_TXFIFO_SIZE - tx_fstat;
> +
> +	for (; i > 0; i--, c->count--, c->buf++)
> +		st_i2c_write_tx_fifo(i2c_dev, *c->buf);
> +}
> +
> +/**
> + * st_i2c_rd_fill_tx_fifo() - Fill the Tx FIFO in read mode
> + * @i2c_dev: Controller's private data
> + *
> + * This functions fills the Tx FIFO with fixed pattern when
> + * in read mode to trigger clock.
> + */
> +static void st_i2c_rd_fill_tx_fifo(struct st_i2c_dev *i2c_dev, int max)
> +{
> +	struct st_i2c_client *c = &i2c_dev->client;
> +	u32 tx_fstat, sta;
> +	int i;
> +
> +	sta = readl(i2c_dev->base + SSC_STA);
> +	if (sta & SSC_STA_TX_FIFO_FULL)
> +		return;
> +
> +	tx_fstat = readl(i2c_dev->base + SSC_TX_FSTAT) & SSC_TX_FSTAT_STATUS;
> +
> +	if (max < (SSC_TXFIFO_SIZE - tx_fstat))
> +		i = max;
> +	else
> +		i = SSC_TXFIFO_SIZE - tx_fstat;
> +
> +	for (; i > 0; i--, c->xfered++)
> +		st_i2c_write_tx_fifo(i2c_dev, 0xff);
> +}
> +
> +static void st_i2c_read_rx_fifo(struct st_i2c_dev *i2c_dev)
> +{
> +	struct st_i2c_client *c = &i2c_dev->client;
> +	u32 i, sta;
> +	u16 rbuf;
> +
> +	sta = readl(i2c_dev->base + SSC_STA);
> +	if (sta & SSC_STA_RIR) {
> +		i = SSC_RXFIFO_SIZE;
> +	} else {
> +		i = readl(i2c_dev->base + SSC_RX_FSTAT);
> +		i &= SSC_RX_FSTAT_STATUS;
> +	}
> +
> +	for (; (i > 0) && (c->count > 0); i--, c->count--) {
> +		rbuf = readl(i2c_dev->base + SSC_RBUF) >> 1;
> +		*c->buf++ = (u8)rbuf & 0xff;
> +	}
> +
> +	if (i) {
> +		dev_err(i2c_dev->dev, "Unexpected %d bytes in rx fifo\n", i);
> +		st_i2c_flush_rx_fifo(i2c_dev);
> +	}
> +}
> +
> +/**
> + * st_i2c_terminate_xfer() - Send either STOP or REPSTART condition
> + * @i2c_dev: Controller's private data
> + */
> +static void st_i2c_terminate_xfer(struct st_i2c_dev *i2c_dev)
> +{
> +	struct st_i2c_client *c = &i2c_dev->client;
> +
> +	st_i2c_clr_bits(i2c_dev->base + SSC_IEN, SSC_IEN_TEEN);
> +	st_i2c_clr_bits(i2c_dev->base + SSC_I2C, SSC_I2C_STRTG);
> +
> +	if (c->stop) {
> +		st_i2c_set_bits(i2c_dev->base + SSC_IEN, SSC_IEN_STOPEN);
> +		st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_STOPG);
> +	} else {
> +		st_i2c_set_bits(i2c_dev->base + SSC_IEN, SSC_IEN_REPSTRTEN);
> +		st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_REPSTRTG);
> +	}
> +}
> +
> +/**
> + * st_i2c_handle_write() - Handle FIFO empty interrupt in case of write
> + * @i2c_dev: Controller's private data
> + */
> +static void st_i2c_handle_write(struct st_i2c_dev *i2c_dev)
> +{
> +	struct st_i2c_client *c = &i2c_dev->client;
> +
> +	st_i2c_flush_rx_fifo(i2c_dev);
> +
> +	if (!c->count)
> +		/* End of xfer, send stop or repstart */
> +		st_i2c_terminate_xfer(i2c_dev);
> +	else
> +		st_i2c_wr_fill_tx_fifo(i2c_dev);
> +}
> +
> +/**
> + * st_i2c_handle_write() - Handle FIFO enmpty interrupt in case of read
> + * @i2c_dev: Controller's private data
> + */
> +static void st_i2c_handle_read(struct st_i2c_dev *i2c_dev)
> +{
> +	struct st_i2c_client *c = &i2c_dev->client;
> +	u32 ien;
> +
> +	/* Trash the address read back */
> +	if (!c->xfered) {
> +		readl(i2c_dev->base + SSC_RBUF);
> +		st_i2c_clr_bits(i2c_dev->base + SSC_I2C, SSC_I2C_TXENB);
> +	} else
> +		st_i2c_read_rx_fifo(i2c_dev);
> +
> +	if (!c->count) {
> +		/* End of xfer, send stop or repstart */
> +		st_i2c_terminate_xfer(i2c_dev);
> +	} else if (c->count == 1) {
> +		/* Penultimate byte to xfer, disable ACK gen. */
> +		st_i2c_clr_bits(i2c_dev->base + SSC_I2C, SSC_I2C_ACKG);
> +
> +		/* Last received byte is to be handled by NACK interrupt */
> +		ien = SSC_IEN_NACKEN | SSC_IEN_ARBLEN;
> +		writel(ien, i2c_dev->base + SSC_IEN);
> +
> +		st_i2c_rd_fill_tx_fifo(i2c_dev, c->count);
> +	} else
> +		st_i2c_rd_fill_tx_fifo(i2c_dev, c->count - 1);
> +}
> +
> +/**
> + * st_i2c_isr() - Interrupt routine
> + * @irq: interrupt number
> + * @data: Controller's private data
> + */
> +static irqreturn_t st_i2c_isr(int irq, void *data)
> +{
> +	struct st_i2c_dev *i2c_dev = data;
> +	struct st_i2c_client *c = &i2c_dev->client;
> +	u32 sta, ien;
> +	int it;
> +
> +	ien = readl(i2c_dev->base + SSC_IEN);
> +	sta = readl(i2c_dev->base + SSC_STA);
> +
> +	/* Use __fls() to check error bits first */
> +	it = __fls(sta & ien);
> +	if (it < 0) {
> +		dev_dbg(i2c_dev->dev, "spurious it (sta=0x%04x, ien=0x%04x)\n",
> +				sta, ien);
> +		return IRQ_NONE;
> +	}
> +
> +	switch (1 << it) {
> +	case SSC_STA_TE:
> +		if (c->addr & I2C_M_RD)
> +			st_i2c_handle_read(i2c_dev);
> +		else
> +			st_i2c_handle_write(i2c_dev);
> +		break;
> +
> +	case SSC_STA_STOP:
> +	case SSC_STA_REPSTRT:
> +		writel(0, i2c_dev->base + SSC_IEN);
> +		complete(&i2c_dev->complete);
> +		break;
> +
> +	case SSC_STA_NACK:
> +		writel(SSC_CLR_NACK, i2c_dev->base + SSC_CLR);
> +
> +		/* Last received byte handled by NACK interrupt */
> +		if ((c->addr & I2C_M_RD) && (c->count == 1) && (c->xfered)) {
> +			st_i2c_handle_read(i2c_dev);
> +			break;
> +		}
> +
> +		it = SSC_IEN_STOPEN | SSC_IEN_ARBLEN;
> +		writel(it, i2c_dev->base + SSC_IEN);
> +
> +		st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_STOPG);
> +		c->result = -EIO;
> +		break;
> +
> +	case SSC_STA_ARBL:
> +		writel(SSC_CLR_SSCARBL, i2c_dev->base + SSC_CLR);
> +
> +		it = SSC_IEN_STOPEN | SSC_IEN_ARBLEN;
> +		writel(it, i2c_dev->base + SSC_IEN);
> +
> +		st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_STOPG);
> +		c->result = -EIO;
> +		break;
> +
> +	default:
> +		dev_err(i2c_dev->dev,
> +				"it %d unhandled (sta=0x%04x)\n", it, sta);
> +	}
> +
> +	return IRQ_HANDLED;
> +}
> +
> +/**
> + * st_i2c_xfer_msg() - Transfer a single I2C message
> + * @i2c_dev: Controller's private data
> + * @msg: I2C message to transfer
> + * @is_first: first message of the sequence
> + * @is_last: last message of the sequence
> + */
> +static int st_i2c_xfer_msg(struct st_i2c_dev *i2c_dev, struct i2c_msg *msg,
> +			    bool is_first, bool is_last)
> +{
> +	struct st_i2c_client *c = &i2c_dev->client;
> +	u32 ctl, i2c, it;
> +	unsigned long timeout;
> +	int ret;
> +
> +	c->addr		= (u8)(msg->addr << 1);
> +	c->addr		|= (msg->flags & I2C_M_RD);
> +	c->buf		= msg->buf;
> +	c->count	= msg->len;
> +	c->xfered	= 0;
> +	c->result	= 0;
> +	c->stop		= is_last;
> +
> +	INIT_COMPLETION(i2c_dev->complete);
> +
> +	ctl = SSC_CTL_EN | SSC_CTL_MS |	SSC_CTL_EN_RX_FIFO | SSC_CTL_EN_TX_FIFO;
> +	st_i2c_set_bits(i2c_dev->base + SSC_CTL, ctl);
> +
> +	i2c = SSC_I2C_TXENB;
> +	if (c->addr & I2C_M_RD)
> +		i2c |= SSC_I2C_ACKG;
> +	st_i2c_set_bits(i2c_dev->base + SSC_I2C, i2c);
> +
> +	/* Write slave address */
> +	st_i2c_write_tx_fifo(i2c_dev, c->addr);
> +
> +	/* Pre-fill Tx fifo with data in case of write */
> +	if (!(c->addr & I2C_M_RD))
> +		st_i2c_wr_fill_tx_fifo(i2c_dev);
> +
> +	it = SSC_IEN_NACKEN | SSC_IEN_TEEN | SSC_IEN_ARBLEN;
> +	writel(it, i2c_dev->base + SSC_IEN);
> +
> +	if (is_first) {
> +		ret = st_i2c_wait_free_bus(i2c_dev);
> +		if (ret)
> +			return ret;
> +
> +		st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_STRTG);
> +	}
> +
> +	timeout = wait_for_completion_timeout(&i2c_dev->complete,
> +			i2c_dev->adap.timeout);
> +	ret = c->result;
> +
> +	if (!timeout) {
> +		dev_err(i2c_dev->dev, "Write to slave 0x%x timed out\n",
> +				c->addr);
> +		ret = -ETIMEDOUT;
> +	}
> +
> +	i2c = SSC_I2C_STOPG | SSC_I2C_REPSTRTG;
> +	st_i2c_clr_bits(i2c_dev->base + SSC_I2C, i2c);
> +
> +	writel(SSC_CLR_SSCSTOP | SSC_CLR_REPSTRT, i2c_dev->base + SSC_CLR);
> +
> +	return ret;
> +}
> +
> +/**
> + * st_i2c_xfer() - Transfer a single I2C message
> + * @i2c_adap: Adapter pointer to the controller
> + * @msgs: Pointer to data to be written.
> + * @num: Number of messages to be executed
> + */
> +static int st_i2c_xfer(struct i2c_adapter *i2c_adap,
> +			struct i2c_msg msgs[], int num)
> +{
> +	struct st_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap);
> +	int ret, i;
> +
> +	i2c_dev->busy = true;
> +
> +	ret = clk_prepare_enable(i2c_dev->clk);
> +	if (ret) {
> +		dev_err(i2c_dev->dev, "Failed to prepare_enable clock\n");
> +		return ret;
> +	}
> +
> +	pinctrl_pm_select_default_state(i2c_dev->dev);
> +
> +	st_i2c_hw_config(i2c_dev);
> +
> +	for (i = 0; (i < num) && !ret; i++)
> +		ret = st_i2c_xfer_msg(i2c_dev, &msgs[i], i == 0, i == num - 1);
> +
> +	pinctrl_pm_select_idle_state(i2c_dev->dev);
> +
> +	clk_disable_unprepare(i2c_dev->clk);
> +
> +	i2c_dev->busy = false;
> +
> +	return (ret < 0) ? ret : i;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int st_i2c_suspend(struct device *dev)
> +{
> +	struct platform_device *pdev =
> +		container_of(dev, struct platform_device, dev);
> +	struct st_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
> +
> +	if (i2c_dev->busy)
> +		return -EBUSY;
> +
> +	pinctrl_pm_select_sleep_state(dev);
> +
> +	return 0;
> +}
> +
> +static int st_i2c_resume(struct device *dev)
> +{
> +	pinctrl_pm_select_default_state(dev);
> +	/* Go in idle state if available */
> +	pinctrl_pm_select_idle_state(dev);
> +
> +	return 0;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(st_i2c_pm, st_i2c_suspend, st_i2c_resume);
> +#define ST_I2C_PM	(&st_i2c_pm)
> +#else
> +#define ST_I2C_PM	NULL
> +#endif
> +
> +static u32 st_i2c_func(struct i2c_adapter *adap)
> +{
> +	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> +}
> +
> +static struct i2c_algorithm st_i2c_algo = {
> +	.master_xfer = st_i2c_xfer,
> +	.functionality = st_i2c_func,
> +};
> +
> +static int st_i2c_of_get_deglitch(struct device_node *np,
> +		struct st_i2c_dev *i2c_dev)
> +{
> +	int ret;
> +
> +	ret = of_property_read_u32(np, "i2c-min-scl-pulse-width-us",
> +			&i2c_dev->deglitch.scl_min_width_us);
> +	if ((ret == -ENODATA) || (ret == -EOVERFLOW)) {
> +		dev_err(i2c_dev->dev, "i2c-min-scl-pulse-width-us invalid\n");
> +		return ret;
> +	}
> +
> +	ret = of_property_read_u32(np, "i2c-min-sda-pulse-width-us",
> +			&i2c_dev->deglitch.sda_min_width_us);
> +	if ((ret == -ENODATA) || (ret == -EOVERFLOW)) {
> +		dev_err(i2c_dev->dev, "i2c-min-sda-pulse-width-us invalid\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int st_i2c_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct st_i2c_dev *i2c_dev;
> +	struct resource *res;
> +	u32 clk_rate;
> +	struct i2c_adapter *adap;
> +	int ret;
> +
> +	i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
> +	if (!i2c_dev)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	i2c_dev->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(i2c_dev->base))
> +		return PTR_ERR(i2c_dev->base);
> +
> +	i2c_dev->irq = irq_of_parse_and_map(np, 0);
> +	if (!i2c_dev->irq) {
> +		dev_err(&pdev->dev, "IRQ missing or invalid\n");
> +		return -EINVAL;
> +	}
> +
> +	i2c_dev->clk = of_clk_get_by_name(np, "ssc");
> +	if (IS_ERR(i2c_dev->clk)) {
> +		dev_err(&pdev->dev, "Unable to request clock\n");
> +		return PTR_ERR(i2c_dev->clk);
> +	}
> +
> +	i2c_dev->mode = I2C_MODE_STANDARD;
> +	ret = of_property_read_u32(np, "clock-frequency", &clk_rate);
> +	if ((!ret) && (clk_rate == 400000))
> +		i2c_dev->mode = I2C_MODE_FAST;
> +
> +	i2c_dev->dev = &pdev->dev;
> +
> +	ret = devm_request_irq(&pdev->dev, i2c_dev->irq, st_i2c_isr, 0,
> +			pdev->name, i2c_dev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to request irq %i\n", i2c_dev->irq);
> +		return ret;
> +	}
> +
> +	pinctrl_pm_select_default_state(i2c_dev->dev);
> +	/* In case idle state available, select it */
> +	pinctrl_pm_select_idle_state(i2c_dev->dev);
> +
> +	ret = st_i2c_of_get_deglitch(np, i2c_dev);
> +	if (ret)
> +		return ret;
> +
> +	adap = &i2c_dev->adap;
> +	i2c_set_adapdata(adap, i2c_dev);
> +	snprintf(adap->name, sizeof(adap->name), "ST I2C(0x%08x)", res->start);
> +	adap->owner = THIS_MODULE;
> +	adap->timeout = 2 * HZ;
> +	adap->retries = 0;
> +	adap->class = I2C_CLASS_HWMON | I2C_CLASS_DDC | I2C_CLASS_SPD;
> +	adap->algo = &st_i2c_algo;
> +	adap->dev.parent = &pdev->dev;
> +	adap->dev.of_node = pdev->dev.of_node;
> +
> +	init_completion(&i2c_dev->complete);
> +
> +	ret = i2c_add_adapter(adap);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Failed to add adapter\n");
> +		return ret;
> +	}
> +
> +	platform_set_drvdata(pdev, i2c_dev);
> +
> +	dev_info(i2c_dev->dev, "%s initialized\n", adap->name);
> +
> +	return 0;
> +}
> +
> +static int st_i2c_remove(struct platform_device *pdev)
> +{
> +	struct st_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
> +
> +	i2c_del_adapter(&i2c_dev->adap);
> +
> +	return 0;
> +}
> +
> +static struct of_device_id st_i2c_match[] = {
> +	{ .compatible = "st,comms-ssc-i2c", },
the rules is to put the first soc that use the ip in the compatible
as st,sti7100-scc-i2c

Best Regards,
J.
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