i2c: fsi: Add abort and hardware reset procedures

Add abort procedure for failed transfers. Add engine reset procedure
that is executed during the abort to recover from various fault
conditions.

Signed-off-by: Eddie James <eajames@linux.vnet.ibm.com>
Tested-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 1d9e9bf..0f0bc88 100644 (file)
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -12,10 +12,12 @@
 
 #include <linux/bitfield.h>
 #include <linux/bitops.h>
+#include <linux/delay.h>
 #include <linux/device.h>
 #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>
@@ -128,6 +130,20 @@
 #define I2C_ESTAT_SELF_BUSY    BIT(6)
 #define I2C_ESTAT_VERSION      GENMASK(4, 0)
 
+/* port busy register */
+#define I2C_PORT_BUSY_RESET    BIT(31)
+
+/* wait for command complete or data request */
+#define I2C_CMD_SLEEP_MAX_US   500
+#define I2C_CMD_SLEEP_MIN_US   50
+
+/* wait after reset; choose time from legacy driver */
+#define I2C_RESET_SLEEP_MAX_US 2000
+#define I2C_RESET_SLEEP_MIN_US 1000
+
+/* choose timeout length from legacy driver; it's well tested */
+#define I2C_ABORT_TIMEOUT      msecs_to_jiffies(100)
+
 struct fsi_i2c_master {
        struct fsi_device       *fsi;
        u8                      fifo_size;
@@ -214,6 +230,81 @@ static int fsi_i2c_set_port(struct fsi_i2c_port *port)
        return fsi_i2c_write_reg(fsi, I2C_FSI_RESET_ERR, &dummy);
 }
 
+static int fsi_i2c_reset_engine(struct fsi_i2c_master *i2c, u16 port)
+{
+       int rc;
+       u32 mode, dummy = 0;
+
+       /* reset engine */
+       rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
+       if (rc)
+               return rc;
+
+       /* re-init engine */
+       rc = fsi_i2c_dev_init(i2c);
+       if (rc)
+               return rc;
+
+       rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+       if (rc)
+               return rc;
+
+       /* set port; default after reset is 0 */
+       if (port) {
+               mode &= ~I2C_MODE_PORT;
+               mode |= FIELD_PREP(I2C_MODE_PORT, port);
+               rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+               if (rc)
+                       return rc;
+       }
+
+       /* reset busy register; hw workaround */
+       dummy = I2C_PORT_BUSY_RESET;
+       rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_PORT_BUSY, &dummy);
+       if (rc)
+               return rc;
+
+       return 0;
+}
+
+static int fsi_i2c_abort(struct fsi_i2c_port *port, u32 status)
+{
+       int rc;
+       unsigned long start;
+       u32 cmd = I2C_CMD_WITH_STOP;
+       struct fsi_i2c_master *i2c = port->master;
+       struct fsi_device *fsi = i2c->fsi;
+
+       rc = fsi_i2c_reset_engine(i2c, port->port);
+       if (rc)
+               return rc;
+
+       /* skip final stop command for these errors */
+       if (status & (I2C_STAT_PARITY | I2C_STAT_LOST_ARB | I2C_STAT_STOP_ERR))
+               return 0;
+
+       /* write stop command */
+       rc = fsi_i2c_write_reg(fsi, I2C_FSI_CMD, &cmd);
+       if (rc)
+               return rc;
+
+       /* wait until we see command complete in the master */
+       start = jiffies;
+
+       do {
+               rc = fsi_i2c_read_reg(fsi, I2C_FSI_STAT, &status);
+               if (rc)
+                       return rc;
+
+               if (status & I2C_STAT_CMD_COMP)
+                       return 0;
+
+               usleep_range(I2C_CMD_SLEEP_MIN_US, I2C_CMD_SLEEP_MAX_US);
+       } while (time_after(start + I2C_ABORT_TIMEOUT, jiffies));
+
+       return -ETIMEDOUT;
+}
+
 static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
                        int num)
 {