[PATCH 03/14] fsi: Add mechanism to set the tSendDelay and tEchoDelay values
Benjamin Herrenschmidt
benh at kernel.crashing.org
Wed Jun 27 09:25:54 AEST 2018
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: Benjamin Herrenschmidt <benh at kernel.crashing.org>
---
---
drivers/fsi/fsi-core.c | 109 ++++++++++++++++++++++++++++++++-------
drivers/fsi/fsi-master.h | 2 +
2 files changed, 93 insertions(+), 18 deletions(-)
diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
index 2f6f9b8c75e4..1ae5be31b4bf 100644
--- a/drivers/fsi/fsi-core.c
+++ b/drivers/fsi/fsi-core.c
@@ -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;
@@ -255,11 +257,12 @@ 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,
- &data, sizeof(data));
+ return fsi_master_write(slave->master, slave->link, slave->id,
+ FSI_SLAVE_BASE + FSI_SMODE,
+ &data, sizeof(data));
}
static int fsi_slave_handle_error(struct fsi_slave *slave, bool write,
@@ -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);
}
@@ -665,6 +679,50 @@ 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;
@@ -697,14 +755,6 @@ 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
*/
@@ -733,6 +783,21 @@ 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);
@@ -751,6 +816,10 @@ 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",
@@ -821,12 +890,16 @@ 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)
diff --git a/drivers/fsi/fsi-master.h b/drivers/fsi/fsi-master.h
index ee0b46086026..7d619c68ab9b 100644
--- a/drivers/fsi/fsi-master.h
+++ b/drivers/fsi/fsi-master.h
@@ -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)
--
2.17.1
More information about the openbmc
mailing list