[PATCH v2 1/2] i2c: octeon: thunderx: Check bus state before starting a transaction

[Jan Glauber]

Add an additional status check before starting a transaction. If the
check fails wait for some time to tolerate multi-master mode. After the
timeout expires trigger the recovery.

Signed-off-by: Jan Glauber <jglau...@cavium.com>
---
 drivers/i2c/busses/i2c-octeon-core.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/i2c/busses/i2c-octeon-core.c 
b/drivers/i2c/busses/i2c-octeon-core.c
index 5e63b17..f526511 100644
--- a/drivers/i2c/busses/i2c-octeon-core.c
+++ b/drivers/i2c/busses/i2c-octeon-core.c
@@ -630,6 +630,31 @@ static int octeon_i2c_hlc_comp_write(struct octeon_i2c 
*i2c, struct i2c_msg *msg
        return ret;
 }
 
+static int octeon_i2c_check_bus(struct octeon_i2c *i2c)
+{
+       u64 end = get_jiffies_64() + i2c->adap.timeout;
+       int stat, lines;
+
+       while (time_before64(get_jiffies_64(), end)) {
+               stat = octeon_i2c_stat_read(i2c);
+
+               /* get I2C line state */
+               lines = octeon_i2c_read_int(i2c) & (TWSI_INT_SCL | 
TWSI_INT_SDA);
+
+               if (stat == STAT_IDLE && lines == (TWSI_INT_SCL | TWSI_INT_SDA))
+                       return 0;
+
+               if (stat == STAT_LOST_ARB_38 || stat == STAT_LOST_ARB_68 ||
+                   stat == STAT_LOST_ARB_78 || stat == STAT_LOST_ARB_B0)
+                       break;
+
+               usleep_range(I2C_OCTEON_EVENT_WAIT / 2, I2C_OCTEON_EVENT_WAIT);
+       }
+
+       /* bus check failed, try to recover */
+       return octeon_i2c_recovery(i2c);
+}
+
 /**
  * octeon_i2c_xfer - The driver's master_xfer function
  * @adap: Pointer to the i2c_adapter structure
@@ -643,6 +668,10 @@ int octeon_i2c_xfer(struct i2c_adapter *adap, struct 
i2c_msg *msgs, int num)
        struct octeon_i2c *i2c = i2c_get_adapdata(adap);
        int i, ret = 0;
 
+       ret = octeon_i2c_check_bus(i2c);
+       if (ret)
+               goto out;
+
        if (num == 1) {
                if (msgs[0].len > 0 && msgs[0].len <= 8) {
                        if (msgs[0].flags & I2C_M_RD)
-- 
1.9.1