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Commit 6cdf5e39 authored by Eddie James's avatar Eddie James Committed by Wolfram Sang
Browse files

i2c: fsi: Add abort and hardware reset procedures 



Add abort procedure for failed transfers. Add engine reset procedure
that is executed during the abort to recover from various fault
conditions.

Signed-off-by: default avatarEddie James <eajames@linux.vnet.ibm.com>
Tested-by: default avatarJoel Stanley <joel@jms.id.au>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent 19b4887a

drivers/i2c/busses/i2c-fsi.c

+91 −0
Original line number Diff line number Diff line
@@ -12,10 +12,12 @@ 


#include <linux/bitfield.h>

#include <linux/bitops.h>

#include <linux/delay.h>

#include <linux/device.h>

#include <linux/errno.h>

#include <linux/fsi.h>

#include <linux/i2c.h>

#include <linux/jiffies.h>

#include <linux/kernel.h>

#include <linux/list.h>

#include <linux/module.h>
@@ -128,6 +130,20 @@ 
#define I2C_ESTAT_SELF_BUSY	BIT(6)

#define I2C_ESTAT_VERSION	GENMASK(4, 0)



/* port busy register */

#define I2C_PORT_BUSY_RESET	BIT(31)



/* wait for command complete or data request */

#define I2C_CMD_SLEEP_MAX_US	500

#define I2C_CMD_SLEEP_MIN_US	50



/* wait after reset; choose time from legacy driver */

#define I2C_RESET_SLEEP_MAX_US	2000

#define I2C_RESET_SLEEP_MIN_US	1000



/* choose timeout length from legacy driver; it's well tested */

#define I2C_ABORT_TIMEOUT	msecs_to_jiffies(100)



struct fsi_i2c_master {

	struct fsi_device	*fsi;

	u8			fifo_size;
@@ -214,6 +230,81 @@ static int fsi_i2c_set_port(struct fsi_i2c_port *port) 
	return fsi_i2c_write_reg(fsi, I2C_FSI_RESET_ERR, &dummy);

}



static int fsi_i2c_reset_engine(struct fsi_i2c_master *i2c, u16 port)

{

	int rc;

	u32 mode, dummy = 0;



	/* reset engine */

	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);

	if (rc)

		return rc;



	/* re-init engine */

	rc = fsi_i2c_dev_init(i2c);

	if (rc)

		return rc;



	rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);

	if (rc)

		return rc;



	/* set port; default after reset is 0 */

	if (port) {

		mode &= ~I2C_MODE_PORT;

		mode |= FIELD_PREP(I2C_MODE_PORT, port);

		rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);

		if (rc)

			return rc;

	}



	/* reset busy register; hw workaround */

	dummy = I2C_PORT_BUSY_RESET;

	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_PORT_BUSY, &dummy);

	if (rc)

		return rc;



	return 0;

}



static int fsi_i2c_abort(struct fsi_i2c_port *port, u32 status)

{

	int rc;

	unsigned long start;

	u32 cmd = I2C_CMD_WITH_STOP;

	struct fsi_i2c_master *i2c = port->master;

	struct fsi_device *fsi = i2c->fsi;



	rc = fsi_i2c_reset_engine(i2c, port->port);

	if (rc)

		return rc;



	/* skip final stop command for these errors */

	if (status & (I2C_STAT_PARITY | I2C_STAT_LOST_ARB | I2C_STAT_STOP_ERR))

		return 0;



	/* write stop command */

	rc = fsi_i2c_write_reg(fsi, I2C_FSI_CMD, &cmd);

	if (rc)

		return rc;



	/* wait until we see command complete in the master */

	start = jiffies;



	do {

		rc = fsi_i2c_read_reg(fsi, I2C_FSI_STAT, &status);

		if (rc)

			return rc;



		if (status & I2C_STAT_CMD_COMP)

			return 0;



		usleep_range(I2C_CMD_SLEEP_MIN_US, I2C_CMD_SLEEP_MAX_US);

	} while (time_after(start + I2C_ABORT_TIMEOUT, jiffies));



	return -ETIMEDOUT;

}



static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,

			int num)

{