i2c: exynos5: add conditional reset of hsi2c master before transfer

This patch resets hsi2c master before transfer if related property was set.
HSI2C master can goes into master arbitration lost state if there is the
fluctuation on SCL/SDA line before starting transfer.
To getting out of this state, mater should be reset.

Change-Id: I2487152abff708f61182bbca866f51a421a0c4c9
Signed-off-by: Youngmin Nam <youngmin.nam@samsung.com>

diff --git a/drivers/i2c/busses/i2c-exynos5.c b/drivers/i2c/busses/i2c-exynos5.c
index 4378ecdc8dc0aea51485426d4cd51708710d1439..56cd86c16a332b3ea98d40ac49c2e685555c5b5e 100644 (file)
--- a/drivers/i2c/busses/i2c-exynos5.c
+++ b/drivers/i2c/busses/i2c-exynos5.c
@@ -816,6 +816,16 @@ static int exynos5_i2c_xfer(struct i2c_adapter *adap,
        exynos_update_ip_idle_status(i2c->idle_ip_index, 0);
        clk_prepare_enable(i2c->clk);
 #endif
+
+       /* If master is in arbitration lost state before transfer */
+       /* master should be reset */
+       if (i2c->reset_before_trans) {
+               if (unlikely((readl(i2c->regs + HSI2C_TRANS_STATUS)
+                       & HSI2C_MAST_ST_MASK) == 0xC)) {
+                       i2c->need_hw_init = 1;
+               }
+       }
+
        if (i2c->need_hw_init)
                exynos5_i2c_reset(i2c);
 
@@ -959,6 +969,11 @@ static int exynos5_i2c_probe(struct platform_device *pdev)
        else
                i2c->stop_after_trans = 0;
 
+       if (of_get_property(np, "samsung,reset-before-trans", NULL))
+               i2c->reset_before_trans = 1;
+       else
+               i2c->reset_before_trans = 0;
+
        i2c->idle_ip_index = exynos_get_idle_ip_index(dev_name(&pdev->dev));
 
        strlcpy(i2c->adap.name, "exynos5-i2c", sizeof(i2c->adap.name));

diff --git a/drivers/i2c/busses/i2c-exynos5.h b/drivers/i2c/busses/i2c-exynos5.h
index 70a6bcb15185144e9a2b453d4067cfc1838d0f39..cf299da1838fe7e4b1efd519b3cfa91d756856a3 100644 (file)
--- a/drivers/i2c/busses/i2c-exynos5.h
+++ b/drivers/i2c/busses/i2c-exynos5.h
@@ -54,5 +54,6 @@ struct exynos5_i2c {
        unsigned int            transfer_delay;
 
        int                     idle_ip_index;
+       int                     reset_before_trans;
 };
 #endif /*__I2C_EXYNOS5_H */