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[PATCH v5 0/6] drivers/i2c: Add FSI-attached I2C master algorithm

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  [PATCH v5 0/6] drivers/i2c: Add FSI-attached I2C master algorithm Eddie James <eajames@linux.vnet.ibm.com> - 2017-07-26 19:20 +0200
    [PATCH v5 5/6] drivers/i2c: Add bus recovery for FSI algorithm Eddie James <eajames@linux.vnet.ibm.com> - 2017-07-26 19:20 +0200
    [PATCH v5 3/6] drivers/i2c: Add transfer implementation for FSI algorithm Eddie James <eajames@linux.vnet.ibm.com> - 2017-07-26 19:20 +0200

#1697388 — [PATCH v5 0/6] drivers/i2c: Add FSI-attached I2C master algorithm

From: "Edward A. James" <eajames@us.ibm.com>

This series adds an algorithm for an I2C master physically located on an FSI
slave device. The I2C master has multiple ports, each of which may be connected
to an I2C slave. Access to the I2C master registers is achieved over FSI bus.

Due to the multi-port nature of the I2C master, the driver instantiates a new
I2C adapter for each port connected to a slave. The connected ports should be
defined in the device tree under the I2C master device.

Changes since v4:
 - Add SMBUS flags to functionality mask.
 - Improve probing by continuing parsing the dt if we fail one adapter
   registration. Also don't fail for ENOMEM, as we may have registered some
   ports already.
 - Fix remove() by checking for empty list before iterating.

Edward A. James (6):
  drivers/i2c: Add FSI-attached I2C master algorithm
  drivers/i2c: Add port structure to FSI algorithm
  drivers/i2c: Add transfer implementation for FSI algorithm
  drivers/i2c: Add I2C master locking to FSI algorithm
  drivers/i2c: Add bus recovery for FSI algorithm
  dt-bindings: i2c: Add FSI-attached I2C master dt binding documentation

 Documentation/devicetree/bindings/i2c/i2c-fsi.txt |  40 ++
 drivers/i2c/busses/Kconfig                        |  11 +
 drivers/i2c/busses/Makefile                       |   1 +
 drivers/i2c/busses/i2c-fsi.c                      | 643 ++++++++++++++++++++++
 4 files changed, 695 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/i2c-fsi.txt
 create mode 100644 drivers/i2c/busses/i2c-fsi.c

-- 
1.8.3.1

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#1697390 — [PATCH v5 5/6] drivers/i2c: Add bus recovery for FSI algorithm

From: "Edward A. James" <eajames@us.ibm.com>

Bus recovery should reset the engine and force clock the bus 9 times
to recover most situations.

Signed-off-by: Edward A. James <eajames@us.ibm.com>
---
 drivers/i2c/busses/i2c-fsi.c | 75 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 3a1f317..1af9c01 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -469,6 +469,80 @@ static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
 		| I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA;
 }
 
+static int fsi_i2c_low_level_recover_bus(struct fsi_i2c_master *i2c)
+{
+	int i, rc;
+	u32 mode, dummy = 0;
+
+	rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+	if (rc)
+		return rc;
+
+	mode |= I2C_MODE_DIAG;
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+	if (rc)
+		return rc;
+
+	for (i = 0; i < 9; ++i) {
+		rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
+		if (rc)
+			return rc;
+
+		rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
+		if (rc)
+			return rc;
+	}
+
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
+	if (rc)
+		return rc;
+
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SDA, &dummy);
+	if (rc)
+		return rc;
+
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
+	if (rc)
+		return rc;
+
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SDA, &dummy);
+	if (rc)
+		return rc;
+
+	mode &= ~I2C_MODE_DIAG;
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+
+	return rc;
+}
+
+static int fsi_i2c_recover_bus(struct i2c_adapter *adap)
+{
+	int rc;
+	u32 dummy = 0;
+	struct fsi_i2c_port *port = adap->algo_data;
+	struct fsi_i2c_master *i2c = port->master;
+
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
+	if (rc)
+		return rc;
+
+	rc = fsi_i2c_dev_init(i2c);
+	if (rc)
+		return rc;
+
+	rc = fsi_i2c_low_level_recover_bus(i2c);
+	if (rc)
+		return rc;
+
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
+
+	return rc;
+}
+
+static struct i2c_bus_recovery_info fsi_i2c_bus_recovery_info = {
+	.recover_bus = fsi_i2c_recover_bus,
+};
+
 static const struct i2c_algorithm fsi_i2c_algorithm = {
 	.master_xfer = fsi_i2c_xfer,
 	.functionality = fsi_i2c_functionality,
@@ -512,6 +586,7 @@ static int fsi_i2c_probe(struct device *dev)
 		port->adapter.dev.of_node = np;
 		port->adapter.dev.parent = dev;
 		port->adapter.algo = &fsi_i2c_algorithm;
+		port->adapter.bus_recovery_info = &fsi_i2c_bus_recovery_info;
 		port->adapter.algo_data = port;
 
 		snprintf(port->adapter.name, sizeof(port->adapter.name),
-- 
1.8.3.1

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#1697392 — [PATCH v5 3/6] drivers/i2c: Add transfer implementation for FSI algorithm

From: "Edward A. James" <eajames@us.ibm.com>

Execute I2C transfers from the FSI-attached I2C master. Use polling
instead of interrupts as we have no hardware IRQ over FSI.

Signed-off-by: Edward A. James <eajames@us.ibm.com>
---
 drivers/i2c/busses/i2c-fsi.c | 197 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 195 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 4ad5d68..d37f2c8 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -13,10 +13,12 @@
 #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>
 #include <linux/of.h>
+#include <linux/sched.h>
 
 #define FSI_ENGID_I2C		0x7
 
@@ -140,6 +142,7 @@ struct fsi_i2c_port {
 	struct i2c_adapter	adapter;
 	struct fsi_i2c_master	*master;
 	u16			port;
+	u16			xfrd;
 };
 
 static int fsi_i2c_read_reg(struct fsi_device *fsi, unsigned int reg,
@@ -224,17 +227,207 @@ static int fsi_i2c_set_port(struct fsi_i2c_port *port)
 	return rc;
 }
 
+static int fsi_i2c_start(struct fsi_i2c_port *port, struct i2c_msg *msg,
+			 bool stop)
+{
+	int rc;
+	struct fsi_i2c_master *i2c = port->master;
+	u32 cmd = I2C_CMD_WITH_START | I2C_CMD_WITH_ADDR;
+
+	port->xfrd = 0;
+
+	if (msg->flags & I2C_M_RD)
+		cmd |= I2C_CMD_READ;
+
+	if (stop || msg->flags & I2C_M_STOP)
+		cmd |= I2C_CMD_WITH_STOP;
+
+	cmd = SETFIELD(I2C_CMD_ADDR, cmd, msg->addr >> 1);
+	cmd = SETFIELD(I2C_CMD_LEN, cmd, msg->len);
+
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_CMD, &cmd);
+
+	return rc;
+}
+
+static int fsi_i2c_write_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
+			      u8 fifo_count)
+{
+	int write;
+	int rc = 0;
+	struct fsi_i2c_master *i2c = port->master;
+	int bytes_to_write = i2c->fifo_size - fifo_count;
+	int bytes_remaining = msg->len - port->xfrd;
+
+	if (bytes_to_write > bytes_remaining)
+		bytes_to_write = bytes_remaining;
+
+	while (bytes_to_write > 0) {
+		write = bytes_to_write;
+		/* fsi limited to max 4 byte aligned ops */
+		if (bytes_to_write > 4)
+			write = 4;
+		else if (write == 3)
+			write = 2;
+
+		rc = fsi_device_write(i2c->fsi, I2C_FSI_FIFO,
+				      &msg->buf[port->xfrd], write);
+		if (rc)
+			return rc;
+
+		port->xfrd += write;
+		bytes_to_write -= write;
+	}
+
+	return rc;
+}
+
+static int fsi_i2c_read_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
+			     u8 fifo_count)
+{
+	int read;
+	int rc = 0;
+	struct fsi_i2c_master *i2c = port->master;
+	int xfr_remaining = msg->len - port->xfrd;
+	u32 dummy;
+
+	while (fifo_count) {
+		read = fifo_count;
+		/* fsi limited to max 4 byte aligned ops */
+		if (fifo_count > 4)
+			read = 4;
+		else if (read == 3)
+			read = 2;
+
+		if (xfr_remaining) {
+			if (xfr_remaining < read)
+				read = xfr_remaining;
+
+			rc = fsi_device_read(i2c->fsi, I2C_FSI_FIFO,
+					     &msg->buf[port->xfrd], read);
+			if (rc)
+				return rc;
+
+			port->xfrd += read;
+			xfr_remaining -= read;
+		} else {
+			/* no more buffer but data in fifo, need to clear it */
+			rc = fsi_device_read(i2c->fsi, I2C_FSI_FIFO, &dummy,
+					     read);
+			if (rc)
+				return rc;
+		}
+
+		fifo_count -= read;
+	}
+
+	return rc;
+}
+
+static int fsi_i2c_handle_status(struct fsi_i2c_port *port,
+				 struct i2c_msg *msg, u32 status)
+{
+	int rc;
+	u8 fifo_count;
+	struct fsi_i2c_master *i2c = port->master;
+	u32 dummy = 0;
+
+	if (status & I2C_STAT_ERR) {
+		rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
+		if (rc)
+			return rc;
+
+		if (status & I2C_STAT_NACK)
+			return -EFAULT;
+
+		return -EIO;
+	}
+
+	if (status & I2C_STAT_DAT_REQ) {
+		fifo_count = GETFIELD(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);
+
+		return rc;
+	}
+
+	if (status & I2C_STAT_CMD_COMP) {
+		if (port->xfrd < msg->len)
+			rc = -ENODATA;
+		else
+			rc = msg->len;
+
+		return rc;
+	}
+
+	return 0;
+}
+
+static int fsi_i2c_wait(struct fsi_i2c_port *port, struct i2c_msg *msg,
+			unsigned long timeout)
+{
+	const unsigned long local_timeout = 2; /* jiffies */
+	u32 status = 0;
+	int rc;
+
+	do {
+		rc = fsi_i2c_read_reg(port->master->fsi, I2C_FSI_STAT,
+				      &status);
+		if (rc)
+			return rc;
+
+		if (status & I2C_STAT_ANY_RESP) {
+			rc = fsi_i2c_handle_status(port, msg, status);
+			if (rc < 0)
+				return rc;
+
+			/* cmd complete and all data xfrd */
+			if (rc == msg->len)
+				return 0;
+
+			/* need to xfr more data, but maybe don't need wait */
+			continue;
+		}
+
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		schedule_timeout(local_timeout);
+		timeout = (timeout < local_timeout) ? 0 :
+			timeout - local_timeout;
+	} while (timeout);
+
+	return -ETIME;
+}
+
 static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 			int num)
 {
-	int rc;
+	int i, rc;
+	unsigned long start_time;
 	struct fsi_i2c_port *port = adap->algo_data;
+	struct i2c_msg *msg;
 
 	rc = fsi_i2c_set_port(port);
 	if (rc)
 		return rc;
 
-	return -EOPNOTSUPP;
+	for (i = 0; i < num; ++i) {
+		msg = msgs + i;
+		start_time = jiffies;
+
+		rc = fsi_i2c_start(port, msg, i == num - 1);
+		if (rc)
+			return rc;
+
+		rc = fsi_i2c_wait(port, msg,
+				  adap->timeout - (jiffies - start_time));
+		if (rc)
+			return rc;
+	}
+
+	return 0;
 }
 
 static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
-- 
1.8.3.1

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