libertas: get SD8688 rx length with one CMD52

Usually, the 16-bit rx length is read from scratch pad registers
with two CMD52 transactions:
SD8385: 	IF_SDIO_SCRATCH_OLD (0x80fe/0x80ff)
SD8686/SD8688:	IF_SDIO_SCRATCH     (0x34/0x35)

Alternatively, SD8688 firmware offers an enhanced method for driver
to read an 8-bit rx length (in units) with a single CMD52:
IF_SDIO_RX_UNIT 0x43 is read one time after firmware is ready.
IF_SDIO_RX_LEN  0x42 is read every time when rx interrupt is received.

Signed-off-by: Bing Zhao <bzhao@marvell.com>
Acked-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 55 insertions, 2 deletions

diff --git a/drivers/net/wireless/libertas/if_sdio.c b/drivers/net/wireless/libertas/if_sdio.c
index 69d7fd31319a..e998c123e0c5 100644
--- a/drivers/net/wireless/libertas/if_sdio.c
+++ b/drivers/net/wireless/libertas/if_sdio.c
@@ -107,6 +107,8 @@ struct if_sdio_card {
 
         struct workqueue_struct *workqueue;
         struct work_struct      packet_worker;
+
+        u8                      rx_unit;
 };
 
 /********************************************************************/
@@ -136,6 +138,46 @@ static u16 if_sdio_read_scratch(struct if_sdio_card *card, int *err)
         return scratch;
 }
 
+static u8 if_sdio_read_rx_unit(struct if_sdio_card *card)
+{
+        int ret;
+        u8 rx_unit;
+
+        rx_unit = sdio_readb(card->func, IF_SDIO_RX_UNIT, &ret);
+
+        if (ret)
+                rx_unit = 0;
+
+        return rx_unit;
+}
+
+static u16 if_sdio_read_rx_len(struct if_sdio_card *card, int *err)
+{
+        int ret;
+        u16 rx_len;
+
+        switch (card->model) {
+        case IF_SDIO_MODEL_8385:
+        case IF_SDIO_MODEL_8686:
+                rx_len = if_sdio_read_scratch(card, &ret);
+                break;
+        case IF_SDIO_MODEL_8688:
+        default: /* for newer chipsets */
+                rx_len = sdio_readb(card->func, IF_SDIO_RX_LEN, &ret);
+                if (!ret)
+                        rx_len <<= card->rx_unit;
+                else
+                        rx_len = 0xffff;        /* invalid length */
+
+                break;
+        }
+
+        if (err)
+                *err = ret;
+
+        return rx_len;
+}
+
 static int if_sdio_handle_cmd(struct if_sdio_card *card,
                 u8 *buffer, unsigned size)
 {
@@ -254,7 +296,7 @@ static int if_sdio_card_to_host(struct if_sdio_card *card)
 
         lbs_deb_enter(LBS_DEB_SDIO);
 
-        size = if_sdio_read_scratch(card, &ret);
+        size = if_sdio_read_rx_len(card, &ret);
         if (ret)
                 goto out;
 
@@ -923,10 +965,21 @@ static int if_sdio_probe(struct sdio_func *func,
 
         priv->fw_ready = 1;
 
+        sdio_claim_host(func);
+
+        /*
+         * Get rx_unit if the chip is SD8688 or newer.
+         * SD8385 & SD8686 do not have rx_unit.
+         */
+        if ((card->model != IF_SDIO_MODEL_8385)
+                        && (card->model != IF_SDIO_MODEL_8686))
+                card->rx_unit = if_sdio_read_rx_unit(card);
+        else
+                card->rx_unit = 0;
+
         /*
          * Enable interrupts now that everything is set up
          */
-        sdio_claim_host(func);
         sdio_writeb(func, 0x0f, IF_SDIO_H_INT_MASK, &ret);
         sdio_release_host(func);
         if (ret)