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Commit 1fa847d7 authored by Jeremy Kerr's avatar Jeremy Kerr Committed by Greg Kroah-Hartman
Browse files

drivers/fsi: Add error handling for slave 



This change implements error handling in the FSI core, by cleaining up
and retrying failed operations, using the SISC, TERM and BREAK
facilities.

Signed-off-by: default avatarJeremy Kerr <jk@ozlabs.org>
Signed-off-by: default avatarChristopher Bostic <cbostic@linux.vnet.ibm.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 66433b05

drivers/fsi/fsi-core.c

+114 −7
Original line number Diff line number Diff line
@@ -47,6 +47,8 @@ static const int engine_page_size = 0x400; 
 * FSI slave engine control register offsets

 */

#define FSI_SMODE		0x0	/* R/W: Mode register */

#define FSI_SISC		0x8	/* R/W: Interrupt condition */

#define FSI_SSTAT		0x14	/* R  : Slave status */



/*

 * SMODE fields
@@ -77,10 +79,14 @@ struct fsi_slave { 
#define to_fsi_master(d) container_of(d, struct fsi_master, dev)

#define to_fsi_slave(d) container_of(d, struct fsi_slave, dev)



static const int slave_retries = 2;

static int discard_errors;



static int fsi_master_read(struct fsi_master *master, int link,

		uint8_t slave_id, uint32_t addr, void *val, size_t size);

static int fsi_master_write(struct fsi_master *master, int link,

		uint8_t slave_id, uint32_t addr, const void *val, size_t size);

static int fsi_master_break(struct fsi_master *master, int link);



/*

 * fsi_device_read() / fsi_device_write() / fsi_device_peek()
@@ -173,18 +179,107 @@ static int fsi_slave_calc_addr(struct fsi_slave *slave, uint32_t *addrp, 
	return 0;

}



int fsi_slave_report_and_clear_errors(struct fsi_slave *slave)

{

	struct fsi_master *master = slave->master;

	uint32_t irq, stat;

	int rc, link;

	uint8_t id;



	link = slave->link;

	id = slave->id;



	rc = fsi_master_read(master, link, id, FSI_SLAVE_BASE + FSI_SISC,

			&irq, sizeof(irq));

	if (rc)

		return rc;



	rc =  fsi_master_read(master, link, id, FSI_SLAVE_BASE + FSI_SSTAT,

			&stat, sizeof(stat));

	if (rc)

		return rc;



	dev_info(&slave->dev, "status: 0x%08x, sisc: 0x%08x\n",

			be32_to_cpu(stat), be32_to_cpu(irq));



	/* clear interrupts */

	return fsi_master_write(master, link, id, FSI_SLAVE_BASE + FSI_SISC,

			&irq, sizeof(irq));

}



static int fsi_slave_set_smode(struct fsi_master *master, int link, int id);



int fsi_slave_handle_error(struct fsi_slave *slave, bool write, uint32_t addr,

		size_t size)

{

	struct fsi_master *master = slave->master;

	int rc, link;

	uint32_t reg;

	uint8_t id;



	if (discard_errors)

		return -1;



	link = slave->link;

	id = slave->id;



	dev_dbg(&slave->dev, "handling error on %s to 0x%08x[%zd]",

			write ? "write" : "read", addr, size);



	/* try a simple clear of error conditions, which may fail if we've lost

	 * communication with the slave

	 */

	rc = fsi_slave_report_and_clear_errors(slave);

	if (!rc)

		return 0;



	/* send a TERM and retry */

	if (master->term) {

		rc = master->term(master, link, id);

		if (!rc) {

			rc = fsi_master_read(master, link, id, 0,

					&reg, sizeof(reg));

			if (!rc)

				rc = fsi_slave_report_and_clear_errors(slave);

			if (!rc)

				return 0;

		}

	}



	/* getting serious, reset the slave via BREAK */

	rc = fsi_master_break(master, link);

	if (rc)

		return rc;



	rc = fsi_slave_set_smode(master, link, id);

	if (rc)

		return rc;



	return fsi_slave_report_and_clear_errors(slave);

}



int fsi_slave_read(struct fsi_slave *slave, uint32_t addr,

			void *val, size_t size)

{

	uint8_t id = slave->id;

	int rc;

	int rc, err_rc, i;



	rc = fsi_slave_calc_addr(slave, &addr, &id);

	if (rc)

		return rc;



	return fsi_master_read(slave->master, slave->link, id,

			addr, val, size);

	for (i = 0; i < slave_retries; i++) {

		rc = fsi_master_read(slave->master, slave->link,

				id, addr, val, size);

		if (!rc)

			break;



		err_rc = fsi_slave_handle_error(slave, false, addr, size);

		if (err_rc)

			break;

	}



	return rc;

}

EXPORT_SYMBOL_GPL(fsi_slave_read);
@@ -192,14 +287,24 @@ int fsi_slave_write(struct fsi_slave *slave, uint32_t addr, 
			const void *val, size_t size)

{

	uint8_t id = slave->id;

	int rc;

	int rc, err_rc, i;



	rc = fsi_slave_calc_addr(slave, &addr, &id);

	if (rc)

		return rc;



	return fsi_master_write(slave->master, slave->link, id,

			addr, val, size);

	for (i = 0; i < slave_retries; i++) {

		rc = fsi_master_write(slave->master, slave->link,

				id, addr, val, size);

		if (!rc)

			break;



		err_rc = fsi_slave_handle_error(slave, true, addr, size);

		if (err_rc)

			break;

	}



	return rc;

}

EXPORT_SYMBOL_GPL(fsi_slave_write);
@@ -770,3 +875,5 @@ static void fsi_exit(void) 


module_init(fsi_init);

module_exit(fsi_exit);

module_param(discard_errors, int, 0664);

MODULE_PARM_DESC(discard_errors, "Don't invoke error handling on bus accesses");