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Commit 9d3ca54b authored by Juergen Fitschen's avatar Juergen Fitschen Committed by Wolfram Sang
Browse files

i2c: at91: added slave mode support 



Slave mode driver is based on the concept of i2c-designware driver.

Signed-off-by: default avatarJuergen Fitschen <me@jue.yt>
[ludovic.desroches@microchip.com: rework Kconfig and replace IS_ENABLED
by defined]
Signed-off-by: default avatarLudovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent ad7d142f

drivers/i2c/busses/Kconfig

+13 −0
Original line number Diff line number Diff line
@@ -387,6 +387,19 @@ config I2C_AT91 
	  the latency to fill the transmission register is too long. If you

	  are facing this situation, use the i2c-gpio driver.



config I2C_AT91_SLAVE_EXPERIMENTAL

	tristate "Microchip AT91 I2C experimental slave mode"

	depends on I2C_AT91

	select I2C_SLAVE

	help

	  If you say yes to this option, support for the slave mode will be

	  added. Caution: do not use it for production. This feature has not

	  been tested in a heavy way, help wanted.

	  There are known bugs:

	    - It can hang, on a SAMA5D4, after several transfers.

	    - There are some mismtaches with a SAMA5D4 as slave and a SAMA5D2 as

	    master.



config I2C_AU1550

	tristate "Au1550/Au1200/Au1300 SMBus interface"

	depends on MIPS_ALCHEMY

drivers/i2c/busses/Makefile

+3 −0
Original line number Diff line number Diff line
@@ -36,6 +36,9 @@ obj-$(CONFIG_I2C_ALTERA) += i2c-altera.o 
obj-$(CONFIG_I2C_ASPEED)	+= i2c-aspeed.o

obj-$(CONFIG_I2C_AT91)		+= i2c-at91.o

i2c-at91-objs			:= i2c-at91-core.o i2c-at91-master.o

ifeq ($(CONFIG_I2C_AT91_SLAVE_EXPERIMENTAL),y)

	i2c-at91-objs		+= i2c-at91-slave.o

endif

obj-$(CONFIG_I2C_AU1550)	+= i2c-au1550.o

obj-$(CONFIG_I2C_AXXIA)		+= i2c-axxia.o

obj-$(CONFIG_I2C_BCM2835)	+= i2c-bcm2835.o

drivers/i2c/busses/i2c-at91-core.c

+10 −3
Original line number Diff line number Diff line
@@ -56,7 +56,9 @@ void at91_init_twi_bus(struct at91_twi_dev *dev) 
{

	at91_disable_twi_interrupts(dev);

	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SWRST);



	if (dev->slave_detected)

		at91_init_twi_bus_slave(dev);

	else

		at91_init_twi_bus_master(dev);

}
@@ -239,6 +241,11 @@ static int at91_twi_probe(struct platform_device *pdev) 
	dev->adapter.timeout = AT91_I2C_TIMEOUT;

	dev->adapter.dev.of_node = pdev->dev.of_node;



	dev->slave_detected = i2c_detect_slave_mode(&pdev->dev);



	if (dev->slave_detected)

		rc = at91_twi_probe_slave(pdev, phy_addr, dev);

	else

		rc = at91_twi_probe_master(pdev, phy_addr, dev);

	if (rc)

		return rc;

drivers/i2c/busses/i2c-at91-slave.c

0 → 100644
+143 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 *  i2c slave support for Atmel's AT91 Two-Wire Interface (TWI)

 *

 *  Copyright (C) 2017 Juergen Fitschen <me@jue.yt>

 */



#include <linux/err.h>

#include <linux/i2c.h>

#include <linux/interrupt.h>

#include <linux/pm_runtime.h>



#include "i2c-at91.h"



static irqreturn_t atmel_twi_interrupt_slave(int irq, void *dev_id)

{

	struct at91_twi_dev *dev = dev_id;

	const unsigned status = at91_twi_read(dev, AT91_TWI_SR);

	const unsigned irqstatus = status & at91_twi_read(dev, AT91_TWI_IMR);

	u8 value;



	if (!irqstatus)

		return IRQ_NONE;



	/* slave address has been detected on I2C bus */

	if (irqstatus & AT91_TWI_SVACC) {

		if (status & AT91_TWI_SVREAD) {

			i2c_slave_event(dev->slave,

					I2C_SLAVE_READ_REQUESTED, &value);

			writeb_relaxed(value, dev->base + AT91_TWI_THR);

			at91_twi_write(dev, AT91_TWI_IER,

				       AT91_TWI_TXRDY | AT91_TWI_EOSACC);

		} else {

			i2c_slave_event(dev->slave,

					I2C_SLAVE_WRITE_REQUESTED, &value);

			at91_twi_write(dev, AT91_TWI_IER,

				       AT91_TWI_RXRDY | AT91_TWI_EOSACC);

		}

		at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_SVACC);

	}



	/* byte transmitted to remote master */

	if (irqstatus & AT91_TWI_TXRDY) {

		i2c_slave_event(dev->slave, I2C_SLAVE_READ_PROCESSED, &value);

		writeb_relaxed(value, dev->base + AT91_TWI_THR);

	}



	/* byte received from remote master */

	if (irqstatus & AT91_TWI_RXRDY) {

		value = readb_relaxed(dev->base + AT91_TWI_RHR);

		i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED, &value);

	}



	/* master sent stop */

	if (irqstatus & AT91_TWI_EOSACC) {

		at91_twi_write(dev, AT91_TWI_IDR,

			       AT91_TWI_TXRDY | AT91_TWI_RXRDY | AT91_TWI_EOSACC);

		at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_SVACC);

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

	}



	return IRQ_HANDLED;

}



static int at91_reg_slave(struct i2c_client *slave)

{

	struct at91_twi_dev *dev = i2c_get_adapdata(slave->adapter);



	if (dev->slave)

		return -EBUSY;



	if (slave->flags & I2C_CLIENT_TEN)

		return -EAFNOSUPPORT;



	/* Make sure twi_clk doesn't get turned off! */

	pm_runtime_get_sync(dev->dev);



	dev->slave = slave;

	dev->smr = AT91_TWI_SMR_SADR(slave->addr);



	at91_init_twi_bus(dev);

	at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_SVACC);



	dev_info(dev->dev, "entered slave mode (ADR=%d)\n", slave->addr);



	return 0;

}



static int at91_unreg_slave(struct i2c_client *slave)

{

	struct at91_twi_dev *dev = i2c_get_adapdata(slave->adapter);



	WARN_ON(!dev->slave);



	dev_info(dev->dev, "leaving slave mode\n");



	dev->slave = NULL;

	dev->smr = 0;



	at91_init_twi_bus(dev);



	pm_runtime_put(dev->dev);



	return 0;

}



static u32 at91_twi_func(struct i2c_adapter *adapter)

{

	return I2C_FUNC_SLAVE | I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL

		| I2C_FUNC_SMBUS_READ_BLOCK_DATA;

}



static const struct i2c_algorithm at91_twi_algorithm_slave = {

	.reg_slave	= at91_reg_slave,

	.unreg_slave	= at91_unreg_slave,

	.functionality	= at91_twi_func,

};



int at91_twi_probe_slave(struct platform_device *pdev,

			 u32 phy_addr, struct at91_twi_dev *dev)

{

	int rc;



	rc = devm_request_irq(&pdev->dev, dev->irq, atmel_twi_interrupt_slave,

			      0, dev_name(dev->dev), dev);

	if (rc) {

		dev_err(dev->dev, "Cannot get irq %d: %d\n", dev->irq, rc);

		return rc;

	}



	dev->adapter.algo = &at91_twi_algorithm_slave;



	return 0;

}



void at91_init_twi_bus_slave(struct at91_twi_dev *dev)

{

	at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_MSDIS);

	if (dev->slave_detected && dev->smr) {

		at91_twi_write(dev, AT91_TWI_SMR, dev->smr);

		at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SVEN);

	}

}

drivers/i2c/busses/i2c-at91.h

+29 −1
Original line number Diff line number Diff line
@@ -49,6 +49,10 @@ 
#define	AT91_TWI_IADRSZ_1	0x0100	/* Internal Device Address Size */

#define	AT91_TWI_MREAD		BIT(12)	/* Master Read Direction */



#define	AT91_TWI_SMR		0x0008	/* Slave Mode Register */

#define	AT91_TWI_SMR_SADR_MAX	0x007f

#define	AT91_TWI_SMR_SADR(x)	(((x) & AT91_TWI_SMR_SADR_MAX) << 16)



#define	AT91_TWI_IADR		0x000c	/* Internal Address Register */



#define	AT91_TWI_CWGR		0x0010	/* Clock Waveform Generator Reg */
@@ -59,13 +63,17 @@ 
#define	AT91_TWI_TXCOMP		BIT(0)	/* Transmission Complete */

#define	AT91_TWI_RXRDY		BIT(1)	/* Receive Holding Register Ready */

#define	AT91_TWI_TXRDY		BIT(2)	/* Transmit Holding Register Ready */

#define	AT91_TWI_SVREAD		BIT(3)	/* Slave Read */

#define	AT91_TWI_SVACC		BIT(4)	/* Slave Access */

#define	AT91_TWI_OVRE		BIT(6)	/* Overrun Error */

#define	AT91_TWI_UNRE		BIT(7)	/* Underrun Error */

#define	AT91_TWI_NACK		BIT(8)	/* Not Acknowledged */

#define	AT91_TWI_EOSACC		BIT(11)	/* End Of Slave Access */

#define	AT91_TWI_LOCK		BIT(23) /* TWI Lock due to Frame Errors */



#define	AT91_TWI_INT_MASK \

	(AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY | AT91_TWI_NACK)

	(AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY | AT91_TWI_NACK \

	| AT91_TWI_SVACC | AT91_TWI_EOSACC)



#define	AT91_TWI_IER		0x0024	/* Interrupt Enable Register */

#define	AT91_TWI_IDR		0x0028	/* Interrupt Disable Register */
@@ -133,6 +141,11 @@ struct at91_twi_dev { 
	bool recv_len_abort;

	u32 fifo_size;

	struct at91_twi_dma dma;

	bool slave_detected;

#ifdef CONFIG_I2C_AT91_SLAVE_EXPERIMENTAL

	unsigned smr;

	struct i2c_client *slave;

#endif

};



unsigned at91_twi_read(struct at91_twi_dev *dev, unsigned reg);
@@ -145,3 +158,18 @@ void at91_init_twi_bus(struct at91_twi_dev *dev); 
void at91_init_twi_bus_master(struct at91_twi_dev *dev);

int at91_twi_probe_master(struct platform_device *pdev, u32 phy_addr,

			  struct at91_twi_dev *dev);



#ifdef CONFIG_I2C_AT91_SLAVE_EXPERIMENTAL

void at91_init_twi_bus_slave(struct at91_twi_dev *dev);

int at91_twi_probe_slave(struct platform_device *pdev, u32 phy_addr,

			 struct at91_twi_dev *dev);



#else

static inline void at91_init_twi_bus_slave(struct at91_twi_dev *dev) {}

static inline int at91_twi_probe_slave(struct platform_device *pdev,

				       u32 phy_addr, struct at91_twi_dev *dev)

{

	return -EINVAL;

}



#endif