wl1271: Implementation for SPI busy word checking
Juuso Oikarinen [Thu, 8 Oct 2009 18:56:23 +0000 (21:56 +0300)]
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>

drivers/net/wireless/wl12xx/wl1271.h
drivers/net/wireless/wl12xx/wl1271_spi.c

index c455dcb..957da8c 100644 (file)
@@ -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;
index 4a12880..504991a 100644 (file)
@@ -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);