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Commit a2e7da86 authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt
Browse files

fsi: Add mechanism to set the tSendDelay and tEchoDelay values 



Those values control the amount of "dummy" clocks between commands and
between a command and its response.

This adds a way to configure them from sysfs (to be later extended to
defaults in the device-tree). The default remains 16 (the HW default).

This is only supported if the backend supports the new link_config()
callback to configure the generation of those delays.

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: default avatarJoel Stanley <joel@jms.id.au>
---
parent 935f9636

drivers/fsi/fsi-core.c

+91 −18
Original line number Diff line number Diff line
@@ -81,6 +81,8 @@ struct fsi_slave { 
	int			id;

	int			link;

	uint32_t		size;	/* size of slave address space */

	u8			t_send_delay;

	u8			t_echo_delay;

};



#define to_fsi_master(d) container_of(d, struct fsi_master, dev)
@@ -239,15 +241,15 @@ static inline uint32_t fsi_smode_sid(int x) 
	return (x & FSI_SMODE_SID_MASK) << FSI_SMODE_SID_SHIFT;

}



static uint32_t fsi_slave_smode(int id)

static uint32_t fsi_slave_smode(int id, u8 t_senddly, u8 t_echodly)

{

	return FSI_SMODE_WSC | FSI_SMODE_ECRC

		| fsi_smode_sid(id)

		| fsi_smode_echodly(0xf) | fsi_smode_senddly(0xf)

		| fsi_smode_echodly(t_echodly - 1) | fsi_smode_senddly(t_senddly - 1)

		| fsi_smode_lbcrr(0x8);

}



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

static int fsi_slave_set_smode(struct fsi_slave *slave)

{

	uint32_t smode;

	__be32 data;
@@ -255,10 +257,11 @@ static int fsi_slave_set_smode(struct fsi_master *master, int link, int id) 
	/* set our smode register with the slave ID field to 0; this enables

	 * extended slave addressing

	 */

	smode = fsi_slave_smode(id);

	smode = fsi_slave_smode(slave->id, slave->t_send_delay, slave->t_echo_delay);

	data = cpu_to_be32(smode);



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

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

				FSI_SLAVE_BASE + FSI_SMODE,

				&data, sizeof(data));

}
@@ -268,7 +271,7 @@ static int fsi_slave_handle_error(struct fsi_slave *slave, bool write, 
	struct fsi_master *master = slave->master;

	int rc, link;

	uint32_t reg;

	uint8_t id;

	uint8_t id, send_delay, echo_delay;



	if (discard_errors)

		return -1;
@@ -299,15 +302,26 @@ static int fsi_slave_handle_error(struct fsi_slave *slave, bool write, 
		}

	}



	send_delay = slave->t_send_delay;

	echo_delay = slave->t_echo_delay;



	/* 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);

	slave->t_send_delay = send_delay;

	slave->t_echo_delay = echo_delay;



	rc = fsi_slave_set_smode(slave);

	if (rc)

		return rc;



	if (master->link_config)

		master->link_config(master, link,

				    slave->t_send_delay,

				    slave->t_echo_delay);



	return fsi_slave_report_and_clear_errors(slave);

}
@@ -659,6 +673,50 @@ static struct device_node *fsi_slave_find_of_node(struct fsi_master *master, 
	return NULL;

}



static ssize_t slave_send_echo_show(struct device *dev,

				    struct device_attribute *attr,

				    char *buf)

{

	struct fsi_slave *slave = to_fsi_slave(dev);



	return sprintf(buf, "%u\n", slave->t_send_delay);

}



static ssize_t slave_send_echo_store(struct device *dev,

		struct device_attribute *attr, const char *buf, size_t count)

{

	struct fsi_slave *slave = to_fsi_slave(dev);

	struct fsi_master *master = slave->master;

	unsigned long val;

	int rc;



	if (kstrtoul(buf, 0, &val) < 0)

		return -EINVAL;



	if (val < 1 || val > 16)

		return -EINVAL;



	if (!master->link_config)

		return -ENXIO;



	/* Current HW mandates that send and echo delay are identical */

	slave->t_send_delay = val;

	slave->t_echo_delay = val;



	rc = fsi_slave_set_smode(slave);

	if (rc < 0)

		return rc;

	if (master->link_config)

		master->link_config(master, slave->link,

				    slave->t_send_delay,

				    slave->t_echo_delay);



	return count;

}



static DEVICE_ATTR(send_echo_delays, 0600,

		   slave_send_echo_show, slave_send_echo_store);



static int fsi_slave_init(struct fsi_master *master, int link, uint8_t id)

{

	uint32_t chip_id;
@@ -691,14 +749,6 @@ static int fsi_slave_init(struct fsi_master *master, int link, uint8_t id) 
	dev_dbg(&master->dev, "fsi: found chip %08x at %02x:%02x:%02x\n",

			chip_id, master->idx, link, id);



	rc = fsi_slave_set_smode(master, link, id);

	if (rc) {

		dev_warn(&master->dev,

				"can't set smode on slave:%02x:%02x %d\n",

				link, id, rc);

		return -ENODEV;

	}



	/* If we're behind a master that doesn't provide a self-running bus

	 * clock, put the slave into async mode

	 */
@@ -727,6 +777,21 @@ static int fsi_slave_init(struct fsi_master *master, int link, uint8_t id) 
	slave->link = link;

	slave->id = id;

	slave->size = FSI_SLAVE_SIZE_23b;

	slave->t_send_delay = 16;

	slave->t_echo_delay = 16;



	rc = fsi_slave_set_smode(slave);

	if (rc) {

		dev_warn(&master->dev,

				"can't set smode on slave:%02x:%02x %d\n",

				link, id, rc);

		kfree(slave);

		return -ENODEV;

	}

	if (master->link_config)

		master->link_config(master, link,

				    slave->t_send_delay,

				    slave->t_echo_delay);



	dev_set_name(&slave->dev, "slave@%02x:%02x", link, id);

	rc = device_register(&slave->dev);
@@ -745,6 +810,10 @@ static int fsi_slave_init(struct fsi_master *master, int link, uint8_t id) 
	if (rc)

		dev_warn(&slave->dev, "failed to create term attr: %d\n", rc);



	rc = device_create_file(&slave->dev, &dev_attr_send_echo_delays);

	if (rc)

		dev_warn(&slave->dev, "failed to create delay attr: %d\n", rc);



	rc = fsi_slave_scan(slave);

	if (rc)

		dev_dbg(&master->dev, "failed during slave scan with: %d\n",
@@ -815,12 +884,16 @@ static int fsi_master_link_enable(struct fsi_master *master, int link) 
 */

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

{

	int rc = 0;



	trace_fsi_master_break(master, link);



	if (master->send_break)

		return master->send_break(master, link);

		rc = master->send_break(master, link);

	if (master->link_config)

		master->link_config(master, link, 16, 16);



	return 0;

	return rc;

}



static int fsi_master_scan(struct fsi_master *master)

drivers/fsi/fsi-master.h

+2 −0
Original line number Diff line number Diff line
@@ -33,6 +33,8 @@ struct fsi_master { 
	int		(*term)(struct fsi_master *, int link, uint8_t id);

	int		(*send_break)(struct fsi_master *, int link);

	int		(*link_enable)(struct fsi_master *, int link);

	int		(*link_config)(struct fsi_master *, int link,

				       u8 t_send_delay, u8 t_echo_delay);

};



#define dev_to_fsi_master(d) container_of(d, struct fsi_master, dev)