netdev - [PATCH net-next v3 2/4] net: ipa: use upper_32

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Message-Id: <20210318185930.891260-3-elder@linaro.org>
Date:   Thu, 18 Mar 2021 13:59:28 -0500
From:   Alex Elder <elder@...aro.org>
To:     davem@...emloft.net, kuba@...nel.org
Cc:     f.fainelli@...il.com, bjorn.andersson@...aro.org,
        evgreen@...omium.org, cpratapa@...eaurora.org,
        subashab@...eaurora.org, elder@...nel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH net-next v3 2/4] net: ipa: use upper_32_bits()

Use upper_32_bits() to extract the high-order 32 bits of a DMA
address.  This avoids doing a 32-position shift on a DMA address
if it happens not to be 64 bits wide.  Use lower_32_bits() to
extract the low-order 32 bits (because that's what it's for).

Suggested-by: Florian Fainelli <f.fainelli@...il.com>
Signed-off-by: Alex Elder <elder@...aro.org>
---
v3: - Use upper_32_bits() where appropriate, and lower_32_bits() too.
v2: - Switched to use the upper_32_bits(), as suggested by Florian.

 drivers/net/ipa/gsi.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ipa/gsi.c b/drivers/net/ipa/gsi.c
index 2119367b93ea9..7f3e338ca7a72 100644
--- a/drivers/net/ipa/gsi.c
+++ b/drivers/net/ipa/gsi.c
@@ -351,7 +351,7 @@ void *gsi_ring_virt(struct gsi_ring *ring, u32 index)
 /* Return the 32-bit DMA address associated with a ring index */
 static u32 gsi_ring_addr(struct gsi_ring *ring, u32 index)
 {
-	return (ring->addr & GENMASK(31, 0)) + index * GSI_RING_ELEMENT_SIZE;
+	return lower_32_bits(ring->addr) + index * GSI_RING_ELEMENT_SIZE;
 }
 
 /* Return the ring index of a 32-bit ring offset */
@@ -708,10 +708,9 @@ static void gsi_evt_ring_program(struct gsi *gsi, u32 evt_ring_id)
 	 * high-order 32 bits of the address of the event ring,
 	 * respectively.
 	 */
-	val = evt_ring->ring.addr & GENMASK(31, 0);
+	val = lower_32_bits(evt_ring->ring.addr);
 	iowrite32(val, gsi->virt + GSI_EV_CH_E_CNTXT_2_OFFSET(evt_ring_id));
-
-	val = evt_ring->ring.addr >> 32;
+	val = upper_32_bits(evt_ring->ring.addr);
 	iowrite32(val, gsi->virt + GSI_EV_CH_E_CNTXT_3_OFFSET(evt_ring_id));
 
 	/* Enable interrupt moderation by setting the moderation delay */
@@ -816,10 +815,9 @@ static void gsi_channel_program(struct gsi_channel *channel, bool doorbell)
 	 * high-order 32 bits of the address of the channel ring,
 	 * respectively.
 	 */
-	val = channel->tre_ring.addr & GENMASK(31, 0);
+	val = lower_32_bits(channel->tre_ring.addr);
 	iowrite32(val, gsi->virt + GSI_CH_C_CNTXT_2_OFFSET(channel_id));
-
-	val = channel->tre_ring.addr >> 32;
+	val = upper_32_bits(channel->tre_ring.addr);
 	iowrite32(val, gsi->virt + GSI_CH_C_CNTXT_3_OFFSET(channel_id));
 
 	/* Command channel gets low weighted round-robin priority */
@@ -1365,7 +1363,7 @@ static struct gsi_trans *gsi_event_trans(struct gsi_channel *channel,
 	u32 tre_index;
 
 	/* Event xfer_ptr records the TRE it's associated with */
-	tre_offset = le64_to_cpu(event->xfer_ptr) & GENMASK(31, 0);
+	tre_offset = lower_32_bits(le64_to_cpu(event->xfer_ptr));
 	tre_index = gsi_ring_index(&channel->tre_ring, tre_offset);
 
 	return gsi_channel_trans_mapped(channel, tre_index);
-- 
2.27.0