[RFC linux dev-4.7 6/7] drivers: i2c: Add bus recovery for FSI algorithm

[Eddie James]

From: "Edward A. James" <eajames at 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 at us.ibm.com>
---
 drivers/i2c/busses/i2c-fsi.c | 82 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 1d16440..73931ee 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -457,11 +457,93 @@ static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
 	return I2C_FUNC_I2C | I2C_FUNC_PROTOCOL_MANGLING | I2C_FUNC_10BIT_ADDR;
 }
 
+static int fsi_i2c_low_level_recover_bus(struct fsi_i2c_master *i2c)
+{
+	int i, rc;
+	u32 mode, dummy = 0;
+
+	rc = fsi_device_read(i2c->fsi, I2C_FSI_MODE, &mode, sizeof(mode));
+	if (rc)
+		return rc;
+
+	mode |= I2C_MODE_DIAG;
+	rc = fsi_device_write(i2c->fsi, I2C_FSI_MODE, &mode, sizeof(mode));
+	if (rc)
+		return rc;
+
+	for (i = 0; i < 9; ++i) {
+		rc = fsi_device_write(i2c->fsi, I2C_FSI_RESET_SCL, &dummy,
+				      sizeof(dummy));
+		if (rc)
+			return rc;
+
+		rc = fsi_device_write(i2c->fsi, I2C_FSI_SET_SCL, &dummy,
+				      sizeof(dummy));
+		if (rc)
+			return rc;
+	}
+
+	rc = fsi_device_write(i2c->fsi, I2C_FSI_RESET_SCL, &dummy,
+			      sizeof(dummy));
+	if (rc)
+		return rc;
+
+	rc = fsi_device_write(i2c->fsi, I2C_FSI_RESET_SDA, &dummy,
+			      sizeof(dummy));
+	if (rc)
+		return rc;
+
+	rc = fsi_device_write(i2c->fsi, I2C_FSI_SET_SCL, &dummy,
+			      sizeof(dummy));
+	if (rc)
+		return rc;
+
+	rc = fsi_device_write(i2c->fsi, I2C_FSI_SET_SDA, &dummy,
+			      sizeof(dummy));
+	if (rc)
+		return rc;
+
+	mode &= ~I2C_MODE_DIAG;
+	rc = fsi_device_write(i2c->fsi, I2C_FSI_MODE, &mode, sizeof(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_device_write(i2c->fsi, I2C_FSI_RESET_I2C, &dummy,
+			      sizeof(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_device_write(i2c->fsi, I2C_FSI_RESET_ERR, &dummy,
+			      sizeof(dummy));
+
+	return rc;
+}
+
 static const struct i2c_algorithm fsi_i2c_algorithm = {
 	.master_xfer = fsi_i2c_xfer,
 	.functionality = fsi_i2c_functionality,
 };
 
+static struct i2c_bus_recovery_info fsi_i2c_bus_recovery_info = {
+	.recover_bus = fsi_i2c_recover_bus,
+};
+
 static const char *compatible_strings[] = {
 	"ibm,power8-i2cm",
 	"ibm,power9-i2cm",
-- 
1.8.3.1