i2c-omap: OMAP3430 Silicon Errata 1.153

When an XRDY/XDR is hit, wait for XUDF before writing data to DATA_REG.
Otherwise some data bytes can be lost while transferring them from the
memory to the I2C interface.

Do a Busy-wait for XUDF, before writing data to DATA_REG. While waiting
if there is NACK | AL, set the appropriate error flags, ack the pending
interrupts and return from the ISR.

Signed-off-by: Moiz Sonasath <m-sonasath@ti.com>
Signed-off-by: Vikram pandita <vikram.pandita@ti.com>
[ben-linux@fluff.org: fixed mail format and added i2c-omap to subject]
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

1 files changed, 23 insertions, 1 deletions

diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 5c508ccf4384..d258b02aef44 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -672,9 +672,10 @@ omap_i2c_isr(int this_irq, void *dev_id)
                         break;
                 }
 
+                err = 0;
+complete:
                 omap_i2c_write_reg(dev, OMAP_I2C_STAT_REG, stat);
 
-                err = 0;
                 if (stat & OMAP_I2C_STAT_NACK) {
                         err |= OMAP_I2C_STAT_NACK;
                         omap_i2c_write_reg(dev, OMAP_I2C_CON_REG,
@@ -764,6 +765,27 @@ omap_i2c_isr(int this_irq, void *dev_id)
                                                         "data to send\n");
                                         break;
                                 }
+
+                                /*
+                                 * OMAP3430 Errata 1.153: When an XRDY/XDR
+                                 * is hit, wait for XUDF before writing data
+                                 * to DATA_REG. Otherwise some data bytes can
+                                 * be lost while transferring them from the
+                                 * memory to the I2C interface.
+                                 */
+
+                                if (cpu_is_omap34xx()) {
+                                                while (!(stat & OMAP_I2C_STAT_XUDF)) {
+                                                        if (stat & (OMAP_I2C_STAT_NACK | OMAP_I2C_STAT_AL)) {
+                                                                omap_i2c_ack_stat(dev, stat & (OMAP_I2C_STAT_XRDY | OMAP_I2C_STAT_XDR));
+                                                                err |= OMAP_I2C_STAT_XUDF;
+                                                                goto complete;
+                                                        }
+                                                        cpu_relax();
+                                                        stat = omap_i2c_read_reg(dev, OMAP_I2C_STAT_REG);
+                                                }
+                                }
+
                                 omap_i2c_write_reg(dev, OMAP_I2C_DATA_REG, w);
                         }
                         omap_i2c_ack_stat(dev,