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authorGerhard Sittig <gsi@denx.de>2013-08-23 15:09:02 +0400
committerMarc Kleine-Budde <mkl@pengutronix.de>2013-08-30 00:49:35 +0400
commit3a09b12e0c2ef26a0e2230606a6159d3038a1572 (patch)
treec0382dcf16c39bd5eed4dbe7878afe18373c5eea /drivers/net/can/mscan
parent7ec06da81d2b98859b558d8d551a0c4e3d9516a3 (diff)
downloadlinux-3a09b12e0c2ef26a0e2230606a6159d3038a1572.tar.xz
can: mscan: add a comment on reg to idx mapping
add a comment about the magic of deriving an MSCAN component index from the peripheral's physical address / register offset Cc: linux-can@vger.kernel.org Cc: netdev@vger.kernel.org Signed-off-by: Gerhard Sittig <gsi@denx.de> Signed-off-by: Anatolij Gustschin <agust@denx.de> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Diffstat (limited to 'drivers/net/can/mscan')
-rw-r--r--drivers/net/can/mscan/mpc5xxx_can.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/net/can/mscan/mpc5xxx_can.c b/drivers/net/can/mscan/mpc5xxx_can.c
index 5b0ee8ef5885..bc422ba3d13b 100644
--- a/drivers/net/can/mscan/mpc5xxx_can.c
+++ b/drivers/net/can/mscan/mpc5xxx_can.c
@@ -148,7 +148,10 @@ static u32 mpc512x_can_get_clock(struct platform_device *ofdev,
goto exit_put;
}
- /* Determine the MSCAN device index from the physical address */
+ /* Determine the MSCAN device index from the peripheral's
+ * physical address. Register address offsets against the
+ * IMMR base are: 0x1300, 0x1380, 0x2300, 0x2380
+ */
pval = of_get_property(ofdev->dev.of_node, "reg", &plen);
BUG_ON(!pval || plen < sizeof(*pval));
clockidx = (*pval & 0x80) ? 1 : 0;