[PATCH v3 32/40] i2c: fsi: Add interrupt support

Eddie James
2024-05-16T18:19:36Z

Optionally support interrupts from the I2C controller so that
the driver can wait rather than poll the status register.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
drivers/i2c/busses/i2c-fsi.c | 215 ++++++++++++++++++++++++++++++---
include/trace/events/i2c_fsi.h | 45 +++++++
2 files changed, 245 insertions(+), 15 deletions(-)
create mode 100644 include/trace/events/i2c_fsi.h

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 614d830419bb8..f8d9bc178ef5b 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -23,6 +23,7 @@
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/slab.h>
+#include <linux/wait.h>

#define FSI_ENGID_I2C 0x7

@@ -87,6 +88,7 @@
#define I2C_INT_STOP_ERR BIT(7)
#define I2C_INT_BUSY BIT(6)
#define I2C_INT_IDLE BIT(5)
+#define I2C_INT_ANY GENMASK(15, 7)

/* status register */
#define I2C_STAT_INV_CMD BIT(31)
@@ -148,21 +150,35 @@
/* choose timeout length from legacy driver; it's well tested */
#define I2C_ABORT_TIMEOUT msecs_to_jiffies(100)

+struct fsi_i2c_port;
+
struct fsi_i2c_master {
struct fsi_device *fsi;
+ struct fsi_i2c_port *port;
struct mutex lock;
+ wait_queue_head_t wait;
u32 clock_div;
u8 fifo_size;
+ bool interrupts;
bool skip_stop;
+ bool abort;
};

struct fsi_i2c_port {
struct i2c_adapter adapter;
struct fsi_i2c_master *master;
+ struct i2c_msg *msgs;
+ int nmsgs;
+ int rc;
+ int i;
u16 port;
u16 xfrd;
+ bool wake;
};

+#define CREATE_TRACE_POINTS
+#include <trace/events/i2c_fsi.h>
+
static int fsi_i2c_read_reg(struct fsi_device *fsi, unsigned int reg,
u32 *data)
{
@@ -192,7 +208,7 @@ static int fsi_i2c_dev_init(struct fsi_i2c_master *i2c)
u32 watermark;
int rc;

- /* since we use polling, disable interrupts */
+ /* start with interrupts disabled */
rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_INT_MASK, 0);
if (rc)
return rc;
@@ -236,22 +252,24 @@ static int fsi_i2c_set_port(struct fsi_i2c_port *port)
return fsi_i2c_write_reg(fsi, I2C_FSI_RESET_ERR, 0);
}

-static int fsi_i2c_start(struct fsi_i2c_port *port, struct i2c_msg *msg,
- bool stop)
+static int fsi_i2c_start(struct fsi_i2c_port *port)
{
u32 cmd = I2C_CMD_WITH_START | I2C_CMD_WITH_ADDR;
+ struct i2c_msg *msg = &port->msgs[port->i];

port->xfrd = 0;

if (msg->flags & I2C_M_RD)
cmd |= I2C_CMD_READ;

- if (stop || msg->flags & I2C_M_STOP)
+ if ((port->i == (port->nmsgs - 1)) || (msg->flags & I2C_M_STOP))
cmd |= I2C_CMD_WITH_STOP;

cmd |= FIELD_PREP(I2C_CMD_ADDR, msg->addr);
cmd |= FIELD_PREP(I2C_CMD_LEN, msg->len);

+ trace_i2c_fsi_start(port, cmd);
+
return fsi_i2c_write_reg(port->master->fsi, I2C_FSI_CMD, cmd);
}

@@ -489,11 +507,38 @@ static int fsi_i2c_abort(struct fsi_i2c_port *port)
if (i2c->skip_stop)
return 0;

+ if (i2c->interrupts) {
+ i2c->abort = true;
+ port->wake = false;
+
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_INT_MASK, I2C_INT_ANY);
+ if (rc)
+ return rc;
+ }
+
/* write stop command */
rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_CMD, cmd);
if (rc)
return rc;

+ if (i2c->interrupts) {
+ rc = wait_event_interruptible_timeout(i2c->wait, port->wake, I2C_ABORT_TIMEOUT);
+ if (rc > 0)
+ return port->rc;
+
+ fsi_i2c_write_reg(i2c->fsi, I2C_FSI_INT_MASK, 0);
+
+ if (!rc) {
+ rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_STAT, &status);
+ if (!rc && (status & I2C_STAT_CMD_COMP))
+ rc = 0;
+ else
+ rc = -ETIMEDOUT;
+ }
+
+ return rc;
+ }
+
/* wait until we see command complete in the master */
start = jiffies;
do {
@@ -564,8 +609,59 @@ static int fsi_i2c_handle_status(struct fsi_i2c_port *port,
return 0;
}

-static int fsi_i2c_wait(struct fsi_i2c_port *port, struct i2c_msg *msg,
- unsigned long timeout)
+static int fsi_i2c_wait_irq(struct fsi_i2c_port *port, unsigned long timeout)
+{
+ int rc;
+
+ port->wake = false;
+
+ rc = fsi_i2c_write_reg(port->master->fsi, I2C_FSI_INT_MASK, I2C_INT_ANY);
+ if (rc)
+ return rc;
+
+ rc = wait_event_interruptible_timeout(port->master->wait, port->wake, timeout);
+ if (rc > 0) {
+ rc = port->rc;
+
+ if (port->master->abort) {
+ int rc2 = fsi_i2c_abort(port);
+
+ if (rc2)
+ return rc2;
+ }
+
+ return rc;
+ }
+
+ /*
+ * The interrupt handler should turn off interrupts once it's done, but in this
+ * case we timed out or were interrupted, so mask them off here.
+ */
+ fsi_i2c_write_reg(port->master->fsi, I2C_FSI_INT_MASK, 0);
+
+ if (!rc) {
+ u32 status;
+
+ rc = fsi_i2c_read_reg(port->master->fsi, I2C_FSI_STAT, &status);
+ if (!rc && (status & I2C_STAT_ANY_RESP)) {
+ rc = fsi_i2c_handle_status(port, &port->msgs[port->i], status);
+ if (rc < 0)
+ return rc;
+
+ /* cmd complete and all data xfrd */
+ if (rc == port->msgs[port->i].len)
+ return 0;
+
+ rc = -ETIMEDOUT;
+ } else {
+ rc = -ETIMEDOUT;
+ }
+ }
+
+ return rc;
+}
+
+static int fsi_i2c_wait_poll(struct fsi_i2c_port *port, unsigned long timeout)
{
unsigned long start = jiffies;
u32 status;
@@ -578,12 +674,12 @@ static int fsi_i2c_wait(struct fsi_i2c_port *port, struct i2c_msg *msg,
return rc;

if (status & I2C_STAT_ANY_RESP) {
- rc = fsi_i2c_handle_status(port, msg, status);
+ rc = fsi_i2c_handle_status(port, &port->msgs[port->i], status);
if (rc < 0)
return rc;

/* cmd complete and all data xfrd */
- if (rc == msg->len)
+ if (rc == port->msgs[port->i].len)
return 0;

/* need to xfr more data, but maybe don't need wait */
@@ -601,9 +697,7 @@ static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
{
struct fsi_i2c_port *port = i2c_get_adapdata(adap);
unsigned long start_time;
- struct i2c_msg *msg;
int rc;
- int i;

mutex_lock(&port->master->lock);

@@ -611,21 +705,28 @@ static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
if (rc)
goto unlock;

- for (i = 0; i < num; i++) {
- msg = msgs + i;
+ port->master->port = port;
+ port->master->abort = false;
+ port->msgs = msgs;
+ port->nmsgs = num;
+ for (port->i = 0; port->i < num; ++port->i) {
start_time = jiffies;

- rc = fsi_i2c_start(port, msg, i == num - 1);
+ rc = fsi_i2c_start(port);
if (rc)
goto unlock;

- rc = fsi_i2c_wait(port, msg,
- adap->timeout - (jiffies - start_time));
+ if (port->master->interrupts)
+ rc = fsi_i2c_wait_irq(port, adap->timeout - (jiffies - start_time));
+ else
+ rc = fsi_i2c_wait_poll(port, adap->timeout - (jiffies - start_time));
if (rc)
goto unlock;
}

unlock:
+ port->msgs = NULL;
+ port->master->port = NULL;
mutex_unlock(&port->master->lock);
return rc ? : num;
}
@@ -636,6 +737,85 @@ static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA;
}

+static irqreturn_t fsi_i2c_irq(int irq, void *data)
+{
+ struct fsi_i2c_master *i2c = data;
+ struct fsi_i2c_port *port;
+ struct i2c_msg *msg;
+ u32 status;
+ int rc;
+
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_INT_MASK, 0);
+ if (rc)
+ return IRQ_NONE;
+
+ if (!i2c->port)
+ return IRQ_HANDLED;
+
+ port = i2c->port;
+ rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_STAT, &status);
+ if (rc)
+ goto wake;
+
+ trace_i2c_fsi_irq(port, status);
+
+ if (i2c->abort) {
+ if (status & I2C_STAT_CMD_COMP) {
+ port->wake = true;
+ goto done;
+ } else {
+ rc = fsi_i2c_error_status_to_rc(status);
+ goto wake;
+ }
+ }
+
+ if (status & I2C_STAT_ERR) {
+ i2c->abort = true;
+ i2c->skip_stop = status & I2C_STAT_SKIP_STOP;
+ rc = fsi_i2c_error_status_to_rc(status);
+ goto wake;
+ }
+
+ if (!port->msgs || port->i >= port->nmsgs) {
+ rc = -ENODEV;
+ goto wake;
+ }
+
+ msg = &port->msgs[port->i];
+ if (status & I2C_STAT_DAT_REQ) {
+ u8 fifo_count = FIELD_GET(I2C_STAT_FIFO_COUNT, status);
+
+ if (msg->flags & I2C_M_RD)
+ rc = fsi_i2c_read_fifo(port, msg, fifo_count);
+ else
+ rc = fsi_i2c_write_fifo(port, msg, fifo_count);
+ } else if (status & I2C_STAT_CMD_COMP) {
+ if (port->xfrd < msg->len) {
+ rc = -ENODATA;
+ } else {
+ ++port->i;
+ if (port->i < port->nmsgs) {
+ rc = fsi_i2c_start(port);
+ } else {
+ port->wake = true;
+ goto done;
+ }
+ }
+ }
+
+ if (!rc)
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_INT_MASK, I2C_INT_ANY);
+
+wake:
+ if (rc)
+ port->wake = true;
+done:
+ port->rc = rc;
+ if (port->wake)
+ wake_up_interruptible_all(&i2c->wait);
+ return IRQ_HANDLED;
+}
+
static struct i2c_bus_recovery_info fsi_i2c_bus_recovery_info = {
.recover_bus = i2c_generic_scl_recovery,
.get_scl = fsi_i2c_get_scl,
@@ -683,6 +863,7 @@ static int fsi_i2c_probe(struct device *dev)
return -ENOMEM;

mutex_init(&i2c->lock);
+ init_waitqueue_head(&i2c->wait);
i2c->fsi = to_fsi_dev(dev);
i2c->clock_div = I2C_DEFAULT_CLK_DIV;

@@ -706,6 +887,10 @@ static int fsi_i2c_probe(struct device *dev)
if (rc)
return rc;

+ rc = fsi_device_request_irq(i2c->fsi, fsi_i2c_irq, i2c);
+ if (!rc)
+ i2c->interrupts = true;
+
ports = FIELD_GET(I2C_STAT_MAX_PORT, stat) + 1;
dev_dbg(dev, "I2C master has %d ports\n", ports);

diff --git a/include/trace/events/i2c_fsi.h b/include/trace/events/i2c_fsi.h
new file mode 100644
index 0000000000000..ac49ae9be356b
--- /dev/null
+++ b/include/trace/events/i2c_fsi.h
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM i2c_fsi
+
+#if !defined(_TRACE_I2C_FSI_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_I2C_FSI_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(i2c_fsi_irq,
+ TP_PROTO(const struct fsi_i2c_port *port, uint32_t status),
+ TP_ARGS(port, status),
+ TP_STRUCT__entry(
+ __field(int, bus)
+ __field(int, msg_idx)
+ __field(uint32_t, status)
+ ),
+ TP_fast_assign(
+ __entry->bus = port->adapter.nr;
+ __entry->msg_idx = port->i;
+ __entry->status = status;
+ ),
+ TP_printk("i2c-%d [%d] status:%08x", __entry->bus, __entry->msg_idx, __entry->status)
+);
+
+TRACE_EVENT(i2c_fsi_start,
+ TP_PROTO(const struct fsi_i2c_port *port, uint32_t command),
+ TP_ARGS(port, command),
+ TP_STRUCT__entry(
+ __field(int, bus)
+ __field(int, msg_idx)
+ __field(uint32_t, command)
+ ),
+ TP_fast_assign(
+ __entry->bus = port->adapter.nr;
+ __entry->msg_idx = port->i;
+ __entry->command = command;
+ ),
+ TP_printk("i2c-%d [%d] command:%08x", __entry->bus, __entry->msg_idx, __entry->command)
+);
+
+#endif
+
+#include <trace/define_trace.h>
--
2.39.3