wl1271: Implementation for SPI busy word checking

This patch adds implementation for checking for SPI busy words - i.e.
honoring a delay request from the WLAN chipset upon reading
registers/memory.

To optimized the average SPI ready by 32 bits, also configure the number
of busywords to one to disable the "fixed-busy-word" functionality.

Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Reviewed-by: Vidhya Govindan <vidhya.govindan@nokia.com>
Signed-off-by: Luciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 75 insertions, 4 deletions

diff --git a/drivers/net/wireless/wl12xx/wl1271.h b/drivers/net/wireless/wl12xx/wl1271.h
index c455dcbae524..957da8c0d9cb 100644
--- a/drivers/net/wireless/wl12xx/wl1271.h
+++ b/drivers/net/wireless/wl12xx/wl1271.h
@@ -107,7 +107,13 @@ enum {
 #define WL1271_FW_NAME "wl1271-fw.bin"
 #define WL1271_NVS_NAME "wl1271-nvs.bin"
 
-#define WL1271_BUSY_WORD_LEN 8
+/*
+ * FIXME: for the wl1271, a busy word count of 1 here will result in a more
+ * optimal SPI interface. There is some SPI bug however, causing RXS time outs
+ * with this mode occasionally on boot, so lets have two for now.
+ */
+#define WL1271_BUSY_WORD_CNT 2
+#define WL1271_BUSY_WORD_LEN (WL1271_BUSY_WORD_CNT * sizeof(u32))
 
 #define WL1271_ELP_HW_STATE_ASLEEP 0
 #define WL1271_ELP_HW_STATE_IRQ    1
@@ -389,7 +395,7 @@ struct wl1271 {
 
         u32 buffer_32;
         u32 buffer_cmd;
-        u8 buffer_busyword[WL1271_BUSY_WORD_LEN];
+        u32 buffer_busyword[WL1271_BUSY_WORD_CNT];
         struct wl1271_rx_descriptor *rx_descriptor;
 
         struct wl1271_fw_status *fw_status;
diff --git a/drivers/net/wireless/wl12xx/wl1271_spi.c b/drivers/net/wireless/wl12xx/wl1271_spi.c
index 4a12880c16a8..504991acb052 100644
--- a/drivers/net/wireless/wl12xx/wl1271_spi.c
+++ b/drivers/net/wireless/wl12xx/wl1271_spi.c
@@ -244,12 +244,75 @@ int wl1271_set_partition(struct wl1271 *wl,
         return 0;
 }
 
+#define WL1271_BUSY_WORD_TIMEOUT 1000
+
+void wl1271_spi_read_busy(struct wl1271 *wl, void *buf, size_t len)
+{
+        struct spi_transfer t[1];
+        struct spi_message m;
+        u32 *busy_buf;
+        int num_busy_bytes = 0;
+
+        wl1271_info("spi read BUSY!");
+
+        /*
+         * Look for the non-busy word in the read buffer, and if found,
+         * read in the remaining data into the buffer.
+         */
+        busy_buf = (u32 *)buf;
+        for (; (u32)busy_buf < (u32)buf + len; busy_buf++) {
+                num_busy_bytes += sizeof(u32);
+                if (*busy_buf & 0x1) {
+                        spi_message_init(&m);
+                        memset(t, 0, sizeof(t));
+                        memmove(buf, busy_buf, len - num_busy_bytes);
+                        t[0].rx_buf = buf + (len - num_busy_bytes);
+                        t[0].len = num_busy_bytes;
+                        spi_message_add_tail(&t[0], &m);
+                        spi_sync(wl->spi, &m);
+                        return;
+                }
+        }
+
+        /*
+         * Read further busy words from SPI until a non-busy word is
+         * encountered, then read the data itself into the buffer.
+         */
+        wl1271_info("spi read BUSY-polling needed!");
+
+        num_busy_bytes = WL1271_BUSY_WORD_TIMEOUT;
+        busy_buf = wl->buffer_busyword;
+        while (num_busy_bytes) {
+                num_busy_bytes--;
+                spi_message_init(&m);
+                memset(t, 0, sizeof(t));
+                t[0].rx_buf = busy_buf;
+                t[0].len = sizeof(u32);
+                spi_message_add_tail(&t[0], &m);
+                spi_sync(wl->spi, &m);
+
+                if (*busy_buf & 0x1) {
+                        spi_message_init(&m);
+                        memset(t, 0, sizeof(t));
+                        t[0].rx_buf = buf;
+                        t[0].len = len;
+                        spi_message_add_tail(&t[0], &m);
+                        spi_sync(wl->spi, &m);
+                        return;
+                }
+        }
+
+        /* The SPI bus is unresponsive, the read failed. */
+        memset(buf, 0, len);
+        wl1271_error("SPI read busy-word timeout!\n");
+}
+
 void wl1271_spi_read(struct wl1271 *wl, int addr, void *buf,
                      size_t len, bool fixed)
 {
         struct spi_transfer t[3];
         struct spi_message m;
-        u8 *busy_buf;
+        u32 *busy_buf;
         u32 *cmd;
 
         cmd = &wl->buffer_cmd;
@@ -281,7 +344,9 @@ void wl1271_spi_read(struct wl1271 *wl, int addr, void *buf,
 
         spi_sync(wl->spi, &m);
 
-        /* FIXME: check busy words */
+        /* Check busy words */
+        if (!(busy_buf[WL1271_BUSY_WORD_CNT - 1] & 0x1))
+                wl1271_spi_read_busy(wl, buf, len);
 
         wl1271_dump(DEBUG_SPI, "spi_read cmd -> ", cmd, sizeof(*cmd));
         wl1271_dump(DEBUG_SPI, "spi_read buf <- ", buf, len);