caif-hsi: Add RX flip buffer

Implement RX flip buffer in the cfhsi_rx_done function,
piggy-backed frames is also supported.
This gives a significant performance gain for CAIF over HSI.

Signed-off-by: Sjur Brændeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 104 insertions, 42 deletions

diff --git a/drivers/net/caif/caif_hsi.c b/drivers/net/caif/caif_hsi.c
index 0a4fc62a381d..c8afd62239e9 100644
--- a/drivers/net/caif/caif_hsi.c
+++ b/drivers/net/caif/caif_hsi.c
@@ -426,6 +426,35 @@ static int cfhsi_rx_desc(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
         return xfer_sz;
 }
 
+static int cfhsi_rx_desc_len(struct cfhsi_desc *desc)
+{
+        int xfer_sz = 0;
+        int nfrms = 0;
+        u16 *plen;
+
+        if ((desc->header & ~CFHSI_PIGGY_DESC) ||
+                        (desc->offset > CFHSI_MAX_EMB_FRM_SZ)) {
+
+                pr_err("Invalid descriptor. %x %x\n", desc->header,
+                                desc->offset);
+                return -EPROTO;
+        }
+
+        /* Calculate transfer length. */
+        plen = desc->cffrm_len;
+        while (nfrms < CFHSI_MAX_PKTS && *plen) {
+                xfer_sz += *plen;
+                plen++;
+                nfrms++;
+        }
+
+        if (xfer_sz % 4) {
+                pr_err("Invalid payload len: %d, ignored.\n", xfer_sz);
+                return -EPROTO;
+        }
+        return xfer_sz;
+}
+
 static int cfhsi_rx_pld(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
 {
         int rx_sz = 0;
@@ -517,8 +546,10 @@ static int cfhsi_rx_pld(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
 static void cfhsi_rx_done(struct cfhsi *cfhsi)
 {
         int res;
-        int desc_pld_len = 0;
+        int desc_pld_len = 0, rx_len, rx_state;
         struct cfhsi_desc *desc = NULL;
+        u8 *rx_ptr, *rx_buf;
+        struct cfhsi_desc *piggy_desc = NULL;
 
         desc = (struct cfhsi_desc *)cfhsi->rx_buf;
 
@@ -534,65 +565,71 @@ static void cfhsi_rx_done(struct cfhsi *cfhsi)
         spin_unlock_bh(&cfhsi->lock);
 
         if (cfhsi->rx_state.state == CFHSI_RX_STATE_DESC) {
-                desc_pld_len = cfhsi_rx_desc(desc, cfhsi);
-                if (desc_pld_len == -ENOMEM)
-                        goto restart;
-                if (desc_pld_len == -EPROTO)
+                desc_pld_len = cfhsi_rx_desc_len(desc);
+
+                if (desc_pld_len < 0)
                         goto out_of_sync;
+
+                rx_buf = cfhsi->rx_buf;
+                rx_len = desc_pld_len;
+                if (desc_pld_len > 0 && (desc->header & CFHSI_PIGGY_DESC))
+                        rx_len += CFHSI_DESC_SZ;
+                if (desc_pld_len == 0)
+                        rx_buf = cfhsi->rx_flip_buf;
         } else {
-                int pld_len;
+                rx_buf = cfhsi->rx_flip_buf;
 
-                if (!cfhsi->rx_state.piggy_desc) {
-                        pld_len = cfhsi_rx_pld(desc, cfhsi);
-                        if (pld_len == -ENOMEM)
-                                goto restart;
-                        if (pld_len == -EPROTO)
-                                goto out_of_sync;
-                        cfhsi->rx_state.pld_len = pld_len;
-                } else {
-                        pld_len = cfhsi->rx_state.pld_len;
-                }
+                rx_len = CFHSI_DESC_SZ;
+                if (cfhsi->rx_state.pld_len > 0 &&
+                                (desc->header & CFHSI_PIGGY_DESC)) {
 
-                if ((pld_len > 0) && (desc->header & CFHSI_PIGGY_DESC)) {
-                        struct cfhsi_desc *piggy_desc;
                         piggy_desc = (struct cfhsi_desc *)
                                 (desc->emb_frm + CFHSI_MAX_EMB_FRM_SZ +
-                                                pld_len);
+                                                cfhsi->rx_state.pld_len);
+
                         cfhsi->rx_state.piggy_desc = true;
 
-                        /* Extract piggy-backed descriptor. */
-                        desc_pld_len = cfhsi_rx_desc(piggy_desc, cfhsi);
-                        if (desc_pld_len == -ENOMEM)
-                                goto restart;
+                        /* Extract payload len from piggy-backed descriptor. */
+                        desc_pld_len = cfhsi_rx_desc_len(piggy_desc);
+                        if (desc_pld_len < 0)
+                                goto out_of_sync;
+
+                        if (desc_pld_len > 0)
+                                rx_len = desc_pld_len;
+
+                        if (desc_pld_len > 0 &&
+                                        (piggy_desc->header & CFHSI_PIGGY_DESC))
+                                rx_len += CFHSI_DESC_SZ;
 
                         /*
                          * Copy needed information from the piggy-backed
                          * descriptor to the descriptor in the start.
                          */
-                        memcpy((u8 *)desc, (u8 *)piggy_desc,
+                        memcpy(rx_buf, (u8 *)piggy_desc,
                                         CFHSI_DESC_SHORT_SZ);
-
+                        /* Mark no embedded frame here */
+                        piggy_desc->offset = 0;
                         if (desc_pld_len == -EPROTO)
                                 goto out_of_sync;
                 }
         }
 
-        memset(&cfhsi->rx_state, 0, sizeof(cfhsi->rx_state));
         if (desc_pld_len) {
-                cfhsi->rx_state.state = CFHSI_RX_STATE_PAYLOAD;
-                cfhsi->rx_ptr = cfhsi->rx_buf + CFHSI_DESC_SZ;
-                cfhsi->rx_len = desc_pld_len;
+                rx_state = CFHSI_RX_STATE_PAYLOAD;
+                rx_ptr = rx_buf + CFHSI_DESC_SZ;
         } else {
-                cfhsi->rx_state.state = CFHSI_RX_STATE_DESC;
-                cfhsi->rx_ptr = cfhsi->rx_buf;
-                cfhsi->rx_len = CFHSI_DESC_SZ;
+                rx_state = CFHSI_RX_STATE_DESC;
+                rx_ptr = rx_buf;
+                rx_len = CFHSI_DESC_SZ;
         }
 
+        /* Initiate next read */
         if (test_bit(CFHSI_AWAKE, &cfhsi->bits)) {
                 /* Set up new transfer. */
                 dev_dbg(&cfhsi->ndev->dev, "%s: Start RX.\n",
-                        __func__);
-                res = cfhsi->dev->cfhsi_rx(cfhsi->rx_ptr, cfhsi->rx_len,
+                                __func__);
+
+                res = cfhsi->dev->cfhsi_rx(rx_ptr, rx_len,
                                 cfhsi->dev);
                 if (WARN_ON(res < 0)) {
                         dev_err(&cfhsi->ndev->dev, "%s: RX error %d.\n",
@@ -601,16 +638,32 @@ static void cfhsi_rx_done(struct cfhsi *cfhsi)
                         cfhsi->ndev->stats.rx_dropped++;
                 }
         }
-        return;
 
-restart:
-        if (++cfhsi->rx_state.retries > CFHSI_MAX_RX_RETRIES) {
-                dev_err(&cfhsi->ndev->dev, "%s: No memory available "
-                        "in %d iterations.\n",
-                        __func__, CFHSI_MAX_RX_RETRIES);
-                BUG();
+        if (cfhsi->rx_state.state == CFHSI_RX_STATE_DESC) {
+                /* Extract payload from descriptor */
+                if (cfhsi_rx_desc(desc, cfhsi) < 0)
+                        goto out_of_sync;
+        } else {
+                /* Extract payload */
+                if (cfhsi_rx_pld(desc, cfhsi) < 0)
+                        goto out_of_sync;
+                if (piggy_desc) {
+                        /* Extract any payload in piggyback descriptor. */
+                        if (cfhsi_rx_desc(piggy_desc, cfhsi) < 0)
+                                goto out_of_sync;
+                }
         }
-        mod_timer(&cfhsi->rx_slowpath_timer, jiffies + 1);
+
+        /* Update state info */
+        memset(&cfhsi->rx_state, 0, sizeof(cfhsi->rx_state));
+        cfhsi->rx_state.state = rx_state;
+        cfhsi->rx_ptr = rx_ptr;
+        cfhsi->rx_len = rx_len;
+        cfhsi->rx_state.pld_len = desc_pld_len;
+        cfhsi->rx_state.piggy_desc = desc->header & CFHSI_PIGGY_DESC;
+
+        if (rx_buf != cfhsi->rx_buf)
+                swap(cfhsi->rx_buf, cfhsi->rx_flip_buf);
         return;
 
 out_of_sync:
@@ -1040,6 +1093,12 @@ int cfhsi_probe(struct platform_device *pdev)
                 goto err_alloc_rx;
         }
 
+        cfhsi->rx_flip_buf = kzalloc(CFHSI_BUF_SZ_RX, GFP_KERNEL);
+        if (!cfhsi->rx_flip_buf) {
+                res = -ENODEV;
+                goto err_alloc_rx_flip;
+        }
+
         /* Pre-calculate inactivity timeout. */
         if (inactivity_timeout != -1) {
                 cfhsi->inactivity_timeout =
@@ -1138,6 +1197,8 @@ int cfhsi_probe(struct platform_device *pdev)
  err_activate:
         destroy_workqueue(cfhsi->wq);
  err_create_wq:
+        kfree(cfhsi->rx_flip_buf);
+ err_alloc_rx_flip:
         kfree(cfhsi->rx_buf);
  err_alloc_rx:
         kfree(cfhsi->tx_buf);
diff --git a/include/net/caif/caif_hsi.h b/include/net/caif/caif_hsi.h
index 8d552519ff67..6db8ecf52aa2 100644
--- a/include/net/caif/caif_hsi.h
+++ b/include/net/caif/caif_hsi.h
@@ -138,6 +138,7 @@ struct cfhsi {
         u8 *rx_ptr;
         u8 *tx_buf;
         u8 *rx_buf;
+        u8 *rx_flip_buf;
         spinlock_t lock;
         int flow_off_sent;
         u32 q_low_mark;