i2c: mvtwsi: Fix mvtwsi not working on sun6i and newer sunxi SoCs

On sun6i and newer IFLG is a write-clear bit which is cleared by writing 1,
rather then a normal r/w bit which is cleared by writing 0.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
applied with fixing 3 checkpatch warnings
in drivers/i2c/mvtwsi.c:
WARNING: line over 80 characters
ERROR: code indent should use tabs where possible
WARNING: please, no spaces at the start of a line

Signed-off-by: Heiko Schocher <hs@denx.de>

diff --git a/drivers/i2c/mvtwsi.c b/drivers/i2c/mvtwsi.c
index 5dc4fbba1fe8c254b99f6f3bf06ddeda5e74ee60..30a5b11f9f3dc59b2f86bf6d44bb2330f911e21e 100644 (file)
--- a/drivers/i2c/mvtwsi.c
+++ b/drivers/i2c/mvtwsi.c
@@ -72,6 +72,17 @@ struct  mvtwsi_registers {
 #define        MVTWSI_CONTROL_TWSIEN   0x00000040
 #define        MVTWSI_CONTROL_INTEN    0x00000080
 
+/*
+ * On sun6i and newer IFLG is a write-clear bit which is cleared by writing 1,
+ * on other platforms it is a normal r/w bit which is cleared by writing 0.
+ */
+
+#ifdef CONFIG_SUNXI_GEN_SUN6I
+#define        MVTWSI_CONTROL_CLEAR_IFLG       0x00000008
+#else
+#define        MVTWSI_CONTROL_CLEAR_IFLG       0x00000000
+#endif
+
 /*
  * Status register values -- only those expected in normal master
  * operation on non-10-bit-address devices; whatever status we don't
@@ -189,7 +200,8 @@ static int twsi_start(struct i2c_adapter *adap, int expected_status)
        /* globally set TWSIEN in case it was not */
        twsi_control_flags |= MVTWSI_CONTROL_TWSIEN;
        /* assert START */
-       writel(twsi_control_flags | MVTWSI_CONTROL_START, &twsi->control);
+       twsi_control_flags |= MVTWSI_CONTROL_START | MVTWSI_CONTROL_CLEAR_IFLG;
+       writel(twsi_control_flags, &twsi->control);
        /* wait for controller to process START */
        return twsi_wait(adap, expected_status);
 }
@@ -204,7 +216,7 @@ static int twsi_send(struct i2c_adapter *adap, u8 byte, int expected_status)
        /* put byte in data register for sending */
        writel(byte, &twsi->data);
        /* clear any pending interrupt -- that'll cause sending */
-       writel(twsi_control_flags, &twsi->control);
+       writel(twsi_control_flags | MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control);
        /* wait for controller to receive byte and check ACK */
        return twsi_wait(adap, expected_status);
 }
@@ -224,7 +236,7 @@ static int twsi_recv(struct i2c_adapter *adap, u8 *byte)
        else
                expected_status = MVTWSI_STATUS_DATA_R_NAK;
        /* acknowledge *previous state* and launch receive */
-       writel(twsi_control_flags, &twsi->control);
+       writel(twsi_control_flags | MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control);
        /* wait for controller to receive byte and assert ACK or NAK */
        status = twsi_wait(adap, expected_status);
        /* if we did receive expected byte then store it */
@@ -246,7 +258,7 @@ static int twsi_stop(struct i2c_adapter *adap, int status)
 
        /* assert STOP */
        control = MVTWSI_CONTROL_TWSIEN | MVTWSI_CONTROL_STOP;
-       writel(control, &twsi->control);
+       writel(control | MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control);
        /* wait for IDLE; IFLG won't rise so twsi_wait() is no use. */
        do {
                stop_status = readl(&twsi->status);