Commit de20d185 authored by Wolfram Sang's avatar Wolfram Sang Committed by Wolfram Sang
Browse files

i2c: rcar: add slave support 



The first I2C slave provider using the new generic interface.

Signed-off-by: default avatarWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent 389be323

drivers/i2c/busses/i2c-rcar.c

+115 −9
Original line number Diff line number Diff line
@@ -48,6 +48,12 @@ 
#define ICMAR	0x20	/* master address */

#define ICRXTX	0x24	/* data port */



/* ICSCR */

#define SDBS	(1 << 3)	/* slave data buffer select */

#define SIE	(1 << 2)	/* slave interface enable */

#define GCAE	(1 << 1)	/* general call address enable */

#define FNA	(1 << 0)	/* forced non acknowledgment */



/* ICMCR */

#define MDBS	(1 << 7)	/* non-fifo mode switch */

#define FSCL	(1 << 6)	/* override SCL pin */
@@ -58,6 +64,15 @@ 
#define FSB	(1 << 1)	/* force stop bit */

#define ESG	(1 << 0)	/* en startbit gen */



/* ICSSR (also for ICSIER) */

#define GCAR	(1 << 6)	/* general call received */

#define STM	(1 << 5)	/* slave transmit mode */

#define SSR	(1 << 4)	/* stop received */

#define SDE	(1 << 3)	/* slave data empty */

#define SDT	(1 << 2)	/* slave data transmitted */

#define SDR	(1 << 1)	/* slave data received */

#define SAR	(1 << 0)	/* slave addr received */



/* ICMSR (also for ICMIE) */

#define MNR	(1 << 6)	/* nack received */

#define MAL	(1 << 5)	/* arbitration lost */
@@ -103,6 +118,7 @@ struct rcar_i2c_priv { 
	u32 icccr;

	u32 flags;

	enum rcar_i2c_type devtype;

	struct i2c_client *slave;

};



#define rcar_i2c_priv_to_dev(p)		((p)->adap.dev.parent)
@@ -126,15 +142,6 @@ static u32 rcar_i2c_read(struct rcar_i2c_priv *priv, int reg) 


static void rcar_i2c_init(struct rcar_i2c_priv *priv)

{

	/*

	 * reset slave mode.

	 * slave mode is not used on this driver

	 */

	rcar_i2c_write(priv, ICSIER, 0);

	rcar_i2c_write(priv, ICSAR, 0);

	rcar_i2c_write(priv, ICSCR, 0);

	rcar_i2c_write(priv, ICSSR, 0);



	/* reset master mode */

	rcar_i2c_write(priv, ICMIER, 0);

	rcar_i2c_write(priv, ICMCR, 0);
@@ -360,6 +367,63 @@ static int rcar_i2c_irq_recv(struct rcar_i2c_priv *priv, u32 msr) 
	return 0;

}



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_REQ_READ_START, &value);

			rcar_i2c_write(priv, ICRXTX, value);

			rcar_i2c_write(priv, ICSIER, SDE | SSR | SAR);

		} else {

			i2c_slave_event(priv->slave, I2C_SLAVE_REQ_WRITE_START, &value);

			rcar_i2c_read(priv, ICRXTX);	/* dummy read */

			rcar_i2c_write(priv, ICSIER, SDR | SSR | SAR);

		}



		rcar_i2c_write(priv, ICSSR, ~SAR & 0xff);

	}



	/* master sent stop */

	if (ssr_filtered & SSR) {

		i2c_slave_event(priv->slave, I2C_SLAVE_STOP, &value);

		rcar_i2c_write(priv, ICSIER, SAR | SSR);

		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_REQ_WRITE_END, &value);

		/* Send NACK in case of error */

		rcar_i2c_write(priv, ICSCR, SIE | SDBS | (ret < 0 ? FNA : 0));

		i2c_slave_event(priv->slave, I2C_SLAVE_REQ_WRITE_START, &value);

		rcar_i2c_write(priv, ICSSR, ~SDR & 0xff);

	}



	/* master wants to read from us */

	if (ssr_filtered & SDE) {

		i2c_slave_event(priv->slave, I2C_SLAVE_REQ_READ_END, &value);

		i2c_slave_event(priv->slave, I2C_SLAVE_REQ_READ_START, &value);

		rcar_i2c_write(priv, ICRXTX, value);

		rcar_i2c_write(priv, ICSSR, ~SDE & 0xff);

	}



	return true;

}



static irqreturn_t rcar_i2c_irq(int irq, void *ptr)

{

	struct rcar_i2c_priv *priv = ptr;
@@ -369,6 +433,9 @@ static irqreturn_t rcar_i2c_irq(int irq, void *ptr) 
	/*-------------- spin lock -----------------*/

	spin_lock(&priv->lock);



	if (rcar_i2c_slave_irq(priv))

		goto exit;



	msr = rcar_i2c_read(priv, ICMSR);



	/* Only handle interrupts that are currently enabled */
@@ -499,6 +566,43 @@ static int rcar_i2c_master_xfer(struct i2c_adapter *adap, 
	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;



	pm_runtime_forbid(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 | SSR);

	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);



	rcar_i2c_write(priv, ICSIER, 0);

	rcar_i2c_write(priv, ICSCR, 0);



	priv->slave = NULL;



	pm_runtime_allow(rcar_i2c_priv_to_dev(priv));



	return 0;

}



static u32 rcar_i2c_func(struct i2c_adapter *adap)

{

	/* This HW can't do SMBUS_QUICK and NOSTART */
@@ -508,6 +612,8 @@ static u32 rcar_i2c_func(struct i2c_adapter *adap) 
static const struct i2c_algorithm rcar_i2c_algo = {

	.master_xfer	= rcar_i2c_master_xfer,

	.functionality	= rcar_i2c_func,

	.reg_slave	= rcar_reg_slave,

	.unreg_slave	= rcar_unreg_slave,

};



static const struct of_device_id rcar_i2c_dt_ids[] = {