net: ipa: add support for inline checksum offload

Starting with IPA v4.5, IP payload checksum offload is implemented
differently.

Prior to v4.5, the IPA hardware appends an rmnet_map_dl_csum_trailer
structure to each packet if checksum offload is enabled in the
download direction (modem->AP).  In the upload direction (AP->modem)
a rmnet_map_ul_csum_header structure is prepended before each sent
packet.

Starting with IPA v4.5, checksum offload is implemented using a
single new rmnet_map_v5_csum_header structure which sits between
the QMAP header and the packet data.  The same header structure
is used in both directions.

The new header contains a header type (CSUM_OFFLOAD); a checksum
flag; and a flag indicating whether any other headers follow this
one.  The checksum flag indicates whether the hardware should
compute (and insert) the checksum on a sent packet.  On a received
packet the checksum flag indicates whether the hardware confirms the
checksum value in the payload is correct.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ipa/ipa_endpoint.c b/drivers/net/ipa/ipa_endpoint.c
index ccc99ad..03719fb 100644 (file)
--- a/drivers/net/ipa/ipa_endpoint.c
+++ b/drivers/net/ipa/ipa_endpoint.c
@@ -457,28 +457,34 @@ int ipa_endpoint_modem_exception_reset_all(struct ipa *ipa)
 static void ipa_endpoint_init_cfg(struct ipa_endpoint *endpoint)
 {
        u32 offset = IPA_REG_ENDP_INIT_CFG_N_OFFSET(endpoint->endpoint_id);
+       enum ipa_cs_offload_en enabled;
        u32 val = 0;
 
        /* FRAG_OFFLOAD_EN is 0 */
        if (endpoint->data->checksum) {
+               enum ipa_version version = endpoint->ipa->version;
+
                if (endpoint->toward_ipa) {
                        u32 checksum_offset;
 
-                       val |= u32_encode_bits(IPA_CS_OFFLOAD_UL,
-                                              CS_OFFLOAD_EN_FMASK);
                        /* Checksum header offset is in 4-byte units */
                        checksum_offset = sizeof(struct rmnet_map_header);
                        checksum_offset /= sizeof(u32);
                        val |= u32_encode_bits(checksum_offset,
                                               CS_METADATA_HDR_OFFSET_FMASK);
+
+                       enabled = version < IPA_VERSION_4_5
+                                       ? IPA_CS_OFFLOAD_UL
+                                       : IPA_CS_OFFLOAD_INLINE;
                } else {
-                       val |= u32_encode_bits(IPA_CS_OFFLOAD_DL,
-                                              CS_OFFLOAD_EN_FMASK);
+                       enabled = version < IPA_VERSION_4_5
+                                       ? IPA_CS_OFFLOAD_DL
+                                       : IPA_CS_OFFLOAD_INLINE;
                }
        } else {
-               val |= u32_encode_bits(IPA_CS_OFFLOAD_NONE,
-                                      CS_OFFLOAD_EN_FMASK);
+               enabled = IPA_CS_OFFLOAD_NONE;
        }
+       val |= u32_encode_bits(enabled, CS_OFFLOAD_EN_FMASK);
        /* CS_GEN_QMB_MASTER_SEL is 0 */
 
        iowrite32(val, endpoint->ipa->reg_virt + offset);
@@ -498,6 +504,27 @@ static void ipa_endpoint_init_nat(struct ipa_endpoint *endpoint)
        iowrite32(val, endpoint->ipa->reg_virt + offset);
 }
 
+static u32
+ipa_qmap_header_size(enum ipa_version version, struct ipa_endpoint *endpoint)
+{
+       u32 header_size = sizeof(struct rmnet_map_header);
+
+       /* Without checksum offload, we just have the MAP header */
+       if (!endpoint->data->checksum)
+               return header_size;
+
+       if (version < IPA_VERSION_4_5) {
+               /* Checksum header inserted for AP TX endpoints only */
+               if (endpoint->toward_ipa)
+                       header_size += sizeof(struct rmnet_map_ul_csum_header);
+       } else {
+               /* Checksum header is used in both directions */
+               header_size += sizeof(struct rmnet_map_v5_csum_header);
+       }
+
+       return header_size;
+}
+
 /**
  * ipa_endpoint_init_hdr() - Initialize HDR endpoint configuration register
  * @endpoint:  Endpoint pointer
@@ -526,13 +553,11 @@ static void ipa_endpoint_init_hdr(struct ipa_endpoint *endpoint)
        u32 val = 0;
 
        if (endpoint->data->qmap) {
-               size_t header_size = sizeof(struct rmnet_map_header);
                enum ipa_version version = ipa->version;
+               size_t header_size;
 
-               /* We might supply a checksum header after the QMAP header */
-               if (endpoint->toward_ipa && endpoint->data->checksum)
-                       header_size += sizeof(struct rmnet_map_ul_csum_header);
-               val |= ipa_header_size_encoded(version, header_size);
+               header_size = ipa_qmap_header_size(version, endpoint);
+               val = ipa_header_size_encoded(version, header_size);
 
                /* Define how to fill fields in a received QMAP header */
                if (!endpoint->toward_ipa) {

diff --git a/drivers/net/ipa/ipa_reg.h b/drivers/net/ipa/ipa_reg.h
index 286ea96..b89dec5 100644 (file)
--- a/drivers/net/ipa/ipa_reg.h
+++ b/drivers/net/ipa/ipa_reg.h
@@ -368,6 +368,7 @@ enum ipa_cs_offload_en {
        IPA_CS_OFFLOAD_NONE             = 0x0,
        IPA_CS_OFFLOAD_UL               = 0x1,  /* Before IPA v4.5 (TX) */
        IPA_CS_OFFLOAD_DL               = 0x2,  /* Before IPA v4.5 (RX) */
+       IPA_CS_OFFLOAD_INLINE           = 0x1,  /* IPA v4.5 (TX and RX) */
 };
 
 /* Valid only for TX (IPA consumer) endpoints */