libertas: Fix sd8686 firmware reload

For the SD8686, we cannot rely on the scratch register to read the firmware
load status, because the same register is used for storing RX packet length.
Broaden the check to account for this.

The module can now be unloaded/reloaded successfully.

Based on the implementation from libertas_tf.
Signed-off-by: Daniel Drake <dsd@laptop.org>
Acked-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: Steve deRosier <steve@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/libertas/if_sdio.c

@@ -684,18 +684,40 @@ static int if_sdio_prog_firmware(struct if_sdio_card *card)
 
 	lbs_deb_enter(LBS_DEB_SDIO);
 
+	/*
+	 * Disable interrupts
+	 */
+	sdio_claim_host(card->func);
+	sdio_writeb(card->func, 0x00, IF_SDIO_H_INT_MASK, &ret);
+	sdio_release_host(card->func);
+
 	sdio_claim_host(card->func);
 	scratch = if_sdio_read_scratch(card, &ret);
 	sdio_release_host(card->func);
 
+	lbs_deb_sdio("firmware status = %#x\n", scratch);
+	lbs_deb_sdio("scratch ret = %d\n", ret);
+
 	if (ret)
 		goto out;
 
-	lbs_deb_sdio("firmware status = %#x\n", scratch);
 
+	/*
+	 * The manual clearly describes that FEDC is the right code to use
+	 * to detect firmware presence, but for SD8686 it is not that simple.
+	 * Scratch is also used to store the RX packet length, so we lose
+	 * the FEDC value early on. So we use a non-zero check in order
+	 * to validate firmware presence.
+	 * Additionally, the SD8686 in the Gumstix always has the high scratch
+	 * bit set, even when the firmware is not loaded. So we have to
+	 * exclude that from the test.
+	 */
 	if (scratch == IF_SDIO_FIRMWARE_OK) {
 		lbs_deb_sdio("firmware already loaded\n");
 		goto success;
+	} else if ((card->model == MODEL_8686) && (scratch & 0x7fff)) {
+		lbs_deb_sdio("firmware may be running\n");
+		goto success;
 	}
 
 	ret = lbs_get_firmware(&card->func->dev, lbs_helper_name, lbs_fw_name,
@@ -709,10 +731,14 @@ static int if_sdio_prog_firmware(struct if_sdio_card *card)
 	if (ret)
 		goto out;
 
+	lbs_deb_sdio("Helper firmware loaded\n");
+
 	ret = if_sdio_prog_real(card, mainfw);
 	if (ret)
 		goto out;
 
+	lbs_deb_sdio("Firmware loaded\n");
+
 success:
 	sdio_claim_host(card->func);
 	sdio_set_block_size(card->func, IF_SDIO_BLOCK_SIZE);
@@ -1042,8 +1068,6 @@ static int if_sdio_probe(struct sdio_func *func,
 	priv->exit_deep_sleep = if_sdio_exit_deep_sleep;
 	priv->reset_deep_sleep_wakeup = if_sdio_reset_deep_sleep_wakeup;
 
-	priv->fw_ready = 1;
-
 	sdio_claim_host(func);
 
 	/*
@@ -1064,6 +1088,8 @@ static int if_sdio_probe(struct sdio_func *func,
 	if (ret)
 		goto reclaim;
 
+	priv->fw_ready = 1;
+
 	/*
 	 * FUNC_INIT is required for SD8688 WLAN/BT multiple functions
 	 */