Patchwork [v4,10/31] net: can: mscan: add a comment on reg to idx mapping

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Submitter Gerhard Sittig
Date Aug. 6, 2013, 8:43 p.m.
Message ID <1375821851-31609-11-git-send-email-gsi@denx.de>
Download mbox | patch
Permalink /patch/265221/
State Accepted
Delegated to: Anatolij Gustschin
Headers show

Comments

Gerhard Sittig - Aug. 6, 2013, 8:43 p.m.
add a comment about the magic of deriving an MSCAN component index
from the peripheral's physical address / register offset

Signed-off-by: Gerhard Sittig <gsi@denx.de>
---
 drivers/net/can/mscan/mpc5xxx_can.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Patch

diff --git a/drivers/net/can/mscan/mpc5xxx_can.c b/drivers/net/can/mscan/mpc5xxx_can.c
index 5b0ee8e..bc422ba 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;