hwrng: omap - Do not access INTMASK_REG on EIP76

The INTMASK_REG register does not exist on EIP76. Due to this, the call:

   omap_rng_write(priv, RNG_INTMASK_REG, RNG_SHUTDOWN_OFLO_MASK);

ends up, through the reg_map_eip76[] array, in accessing the register at
offset 0, which is the RNG_OUTPUT_0_REG. This by itself doesn't cause
any problem, but clearly doesn't enable the interrupt as it was
expected.

On EIP76, the register that allows to enable the interrupt is
RNG_CONTROL_REG. And just like RNG_INTMASK_REG, it's bit 1 of this
register that allows to enable the shutdown_oflo interrupt.

Fixes: 383212425c926 ("hwrng: omap - Add device variant for SafeXcel IP-76 found in Armada 8K")
Cc: <stable@vger.kernel.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/char/hw_random/omap-rng.c b/drivers/char/hw_random/omap-rng.c
index d2866280f1309216763acf7990a95865c7db8c43..b1ad12552b566a6892a7de411e9cd0c65cf25933 100644 (file)
--- a/drivers/char/hw_random/omap-rng.c
+++ b/drivers/char/hw_random/omap-rng.c
@@ -408,7 +408,18 @@ static int of_get_omap_rng_device_details(struct omap_rng_dev *priv,
                                                    "err = %d\n", err);
                }
 
-               omap_rng_write(priv, RNG_INTMASK_REG, RNG_SHUTDOWN_OFLO_MASK);
+               /*
+                * On OMAP4, enabling the shutdown_oflo interrupt is
+                * done in the interrupt mask register. There is no
+                * such register on EIP76, and it's enabled by the
+                * same bit in the control register
+                */
+               if (priv->pdata->regs[RNG_INTMASK_REG])
+                       omap_rng_write(priv, RNG_INTMASK_REG,
+                                      RNG_SHUTDOWN_OFLO_MASK);
+               else
+                       omap_rng_write(priv, RNG_CONTROL_REG,
+                                      RNG_SHUTDOWN_OFLO_MASK);
        }
        return 0;
 }