I2C: Add back zero byte hack temporarily

Add back zero byte hack temporarily

Signed-off-by: Dirk Behme <dirk.behme_at_gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index da897a48c6a18be4da8f357641d558cd8e1f3de7..5308d672255e7fb75cbd3c61e6187288ed438771 100644 (file)
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -36,6 +36,10 @@
 
 #include <asm/io.h>
 
+/* Hack to enable zero length transfers and smbus quick until clean fix
+   is available */
+#define OMAP_HACK
+
 /* timeout waiting for the controller to respond */
 #define OMAP_I2C_TIMEOUT (msecs_to_jiffies(1000))
 
@@ -285,12 +289,16 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
                             struct i2c_msg *msg, int stop)
 {
        struct omap_i2c_dev *dev = i2c_get_adapdata(adap);
+#ifdef OMAP_HACK
+       u8 zero_byte = 0;
+#endif
        int r;
        u16 w;
 
        dev_dbg(dev->dev, "addr: 0x%04x, len: %d, flags: 0x%x, stop: %d\n",
                msg->addr, msg->len, msg->flags, stop);
 
+#ifndef OMAP_HACK
        if (msg->len == 0)
                return -EINVAL;
 
@@ -300,6 +308,27 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
        dev->buf = msg->buf;
        dev->buf_len = msg->len;
 
+#else
+
+       omap_i2c_write_reg(dev, OMAP_I2C_SA_REG, msg->addr);
+       /* REVISIT: Remove this hack when we can get I2C chips from board-*.c
+        *          files
+        * Sigh, seems we can't do zero length transactions. Thus, we
+        * can't probe for devices w/o actually sending/receiving at least
+        * a single byte. So we'll set count to 1 for the zero length
+        * transaction case and hope we don't cause grief for some
+        * arbitrary device due to random byte write/read during
+        * probes.
+        */
+       if (msg->len == 0) {
+               dev->buf = &zero_byte;
+               dev->buf_len = 1;
+       } else {
+               dev->buf = msg->buf;
+               dev->buf_len = msg->len;
+       }
+#endif
+
        omap_i2c_write_reg(dev, OMAP_I2C_CNT_REG, dev->buf_len);
 
        init_completion(&dev->cmd_complete);
@@ -383,7 +412,11 @@ out:
 static u32
 omap_i2c_func(struct i2c_adapter *adap)
 {
+#ifndef OMAP_HACK
        return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
+#else
+       return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+#endif
 }
 
 static inline void