[PATCH 3.13.1 5/9] rsi: SDIO functionality

[Jahnavi <jahnavi.meher@redpinesignals.com>]

From: Jahnavi Meher <jahnavi.meher@redpinesignals.com>

This file adds the rsi_sdio module, enabling the SDIO interface for
the 91x chipsets.

Signed-off-by: Jahnavi Meher <jahnavi.meher@redpinesignals.com>
---

rsi_sdio.c |  941 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 941 insertions(+)

diff -uprN a/drivers/net/wireless/rsi/common/rsi_sdio.c b/drivers/net/wireless/rsi/common/rsi_sdio.c
--- a/drivers/net/wireless/rsi/common/rsi_sdio.c	1970-01-01 05:30:00.000000000 +0530
+++ b/drivers/net/wireless/rsi/common/rsi_sdio.c	2014-01-30 16:24:33.180361123 +0530
@@ -0,0 +1,941 @@
+/**
+ * @file rsi_sdio.c
+ * @author
+ * @version 1.0
+ *
+ * @section LICENSE
+ * Copyright (c) 2013 Redpine Signals Inc.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * @section DESCRIPTION
+ *
+ * The file contains Generic HAL layer for SDIO.
+ */
+
+#include "../include/rsi_main.h"
+#include "../include/rsi_hw_intf.h"
+#include "../include/rsi_device_ops.h"
+
+/**
+ * This function prepares cmd 52 read/write arg
+ *
+ * @param  rw Read/write
+ * @param  func function number
+ * @param  raw indicates whether to perform read after write
+ * @param  address address to which to read/write
+ * @param  writedata data to write
+ * @return argument
+ */
+static unsigned long rsi_sdio_set_cmd52_arg(bool rw,
+					    unsigned char func,
+					    unsigned char raw,
+					    unsigned int address,
+					    unsigned char writedata)
+{
+	return ((rw & 1) << 31) | ((func & 0x7) << 28) |
+		((raw & 1) << 27) | (1 << 26) |
+		((address & 0x1FFFF) << 9) | (1 << 8) |
+		(writedata & 0xFF);
+}
+
+/**
+ * This function issues cmd52 byte write onto the card.
+ *
+ * @param  card Pointer to the mmc_card.
+ * @param  address Address to write.
+ * @param  byte Data to write.
+ * @return Write status.
+ */
+static int rsi_cmd52writebyte(struct mmc_card *card,
+			      unsigned int address,
+			      unsigned char byte)
+{
+	struct mmc_command io_cmd;
+	unsigned long arg;
+
+	memset(&io_cmd, 0, sizeof(io_cmd));
+	arg = rsi_sdio_set_cmd52_arg(1, 0, 0, address, byte);
+	io_cmd.opcode = SD_IO_RW_DIRECT;
+	io_cmd.arg = arg;
+	io_cmd.flags = MMC_RSP_R5 | MMC_CMD_AC;
+
+	return mmc_wait_for_cmd(card->host, &io_cmd, 0);
+}
+
+/**
+ * This function issues cmd52 byte read onto the card.
+ *
+ * @param  card Pointer to the mmc_card.
+ * @param  address Address to read from.
+ * @param  byte Variable to store read value.
+ * @return Read status.
+ */
+static int rsi_cmd52readbyte(struct mmc_card *card,
+			     unsigned int address,
+			     unsigned char *byte)
+{
+	struct mmc_command io_cmd;
+	unsigned long arg;
+	int err;
+
+	memset(&io_cmd, 0, sizeof(io_cmd));
+	arg = rsi_sdio_set_cmd52_arg(0, 0, 0, address, 0);
+	io_cmd.opcode = SD_IO_RW_DIRECT;
+	io_cmd.arg = arg;
+	io_cmd.flags = MMC_RSP_R5 | MMC_CMD_AC;
+
+	err = mmc_wait_for_cmd(card->host, &io_cmd, 0);
+	if ((!err) && (byte))
+		*byte =  io_cmd.resp[0] & 0xFF;
+	return err;
+}
+
+/**
+ * This function issues sdio commands.
+ *
+ * @param  func Pointer to the sdio_func structure.
+ * @param  opcode Opcode value.
+ * @param  arg Arguments to pass.
+ * @param  flags Flags which are set.
+ * @param  resp Pointer to store response.
+ * @return err: command status as 0 or -1.
+ */
+static int rsi_issue_sdiocommand(struct sdio_func *func,
+				 unsigned int opcode,
+				 unsigned int arg,
+				 unsigned int flags,
+				 unsigned int *resp)
+{
+	struct mmc_command cmd;
+	int err;
+	struct mmc_host *host;
+
+	host = func->card->host;
+
+	memset(&cmd, 0, sizeof(struct mmc_command));
+	cmd.opcode = opcode;
+	cmd.arg = arg;
+	cmd.flags = flags;
+	err = mmc_wait_for_cmd(host, &cmd, 3);
+
+	if ((!err) && (resp))
+		*resp = cmd.resp[0];
+
+	return err;
+}
+
+/**
+ * This function is called upon the occurence of an interrupt.
+ *
+ * @param  function Pointer to the sdio_func structure.
+ * @return None.
+ */
+static void rsi_handle_interrupt(struct sdio_func *function)
+{
+	struct rsi_hw *adapter = sdio_get_drvdata(function);
+
+	sdio_release_host(function);
+	rsi_interrupt_handler(adapter->priv);
+	sdio_claim_host(function);
+
+	return;
+}
+
+/**
+ * This function resets and re-initializes the card.
+ *
+ * @param  pfunction Pointer to the sdio_func structure.
+ * @return None.
+ */
+static void rsi_reset_card(struct sdio_func *pfunction)
+{
+	int ret = 0;
+	int err;
+	struct mmc_card *card = pfunction->card;
+	struct mmc_host *host = card->host;
+	unsigned char cmd52_resp;
+	unsigned int clock;
+	unsigned int resp, i;
+	unsigned short rca;
+	int bit = (fls(host->ocr_avail) - 1);
+
+	/* Reset 9110 chip */
+	ret = rsi_cmd52writebyte(pfunction->card,
+				 SDIO_CCCR_ABORT,
+				 (1 << 3));
+
+	/* Card will not send any response as it is getting reset immediately
+	 * Hence expect a timeout status from host controller
+	 */
+	if (ret != -ETIMEDOUT)
+		rsi_dbg(ERR_ZONE, "%s: Reset failed : %d\n", __func__, ret);
+
+	/* Wait for few milli seconds to get rid of residue charges if any */
+	msleep(20);
+
+	/* Initialize the SDIO card */
+	host->ios.vdd = bit;
+	host->ios.chip_select = MMC_CS_DONTCARE;
+	host->ios.bus_mode = MMC_BUSMODE_OPENDRAIN;
+	host->ios.power_mode = MMC_POWER_UP;
+	host->ios.bus_width = MMC_BUS_WIDTH_1;
+	host->ios.timing = MMC_TIMING_LEGACY;
+	host->ops->set_ios(host, &host->ios);
+
+	/**
+	 * This delay should be sufficient to allow the power supply
+	 * to reach the minimum voltage.
+	 */
+	msleep(20);
+
+	host->ios.clock = host->f_min;
+	host->ios.power_mode = MMC_POWER_ON;
+	host->ops->set_ios(host, &host->ios);
+
+	/**
+	 * This delay must be at least 74 clock sizes, or 1 ms, or the
+	 * time required to reach a stable voltage.
+	 */
+	msleep(20);
+
+	/* Issue CMD0. Goto idle state */
+	host->ios.chip_select = MMC_CS_HIGH;
+	host->ops->set_ios(host, &host->ios);
+	msleep(20);
+	err = rsi_issue_sdiocommand(pfunction,
+				    MMC_GO_IDLE_STATE,
+				    0,
+				    (MMC_RSP_NONE | MMC_CMD_BC),
+				    NULL);
+	host->ios.chip_select = MMC_CS_DONTCARE;
+	host->ops->set_ios(host, &host->ios);
+	msleep(20);
+	host->use_spi_crc = 0;
+
+	if (err)
+		rsi_dbg(ERR_ZONE, "%s: CMD0 failed : %d\n", __func__, err);
+
+	if (!host->ocr_avail) {
+		/* Issue CMD5, arg = 0 */
+		err = rsi_issue_sdiocommand(pfunction,
+					    SD_IO_SEND_OP_COND,
+					    0,
+					    (MMC_RSP_R4 | MMC_CMD_BCR),
+					    &resp);
+		if (err) {
+			rsi_dbg(ERR_ZONE, "%s: CMD5 failed : %d\n",
+				__func__, err);
+		}
+		host->ocr_avail = resp;
+	}
+
+	/* Issue CMD5, arg = ocr. Wait till card is ready  */
+	for (i = 0; i < 100; i++) {
+		err = rsi_issue_sdiocommand(pfunction,
+					    SD_IO_SEND_OP_COND,
+					    host->ocr_avail,
+					    (MMC_RSP_R4 | MMC_CMD_BCR),
+					    &resp);
+		if (err) {
+			rsi_dbg(ERR_ZONE, "%s: CMD5 failed : %d\n",
+				__func__, err);
+			break;
+		}
+
+		if (resp & MMC_CARD_BUSY)
+			break;
+		msleep(20);
+	}
+
+	if ((i == 100) || (err)) {
+		rsi_dbg(ERR_ZONE, "%s: card in not ready : %d %d\n",
+			__func__, i, err);
+		return;
+	}
+
+	/* Issue CMD3, get RCA */
+	err = rsi_issue_sdiocommand(pfunction,
+				    SD_SEND_RELATIVE_ADDR,
+				    0,
+				    (MMC_RSP_R6 | MMC_CMD_BCR),
+				    &resp);
+	if (err) {
+		rsi_dbg(ERR_ZONE, "%s: CMD3 failed : %d\n", __func__, err);
+		return;
+	}
+	rca = resp >> 16;
+	host->ios.bus_mode = MMC_BUSMODE_PUSHPULL;
+	host->ops->set_ios(host, &host->ios);
+
+	/* Issue CMD7, select card  */
+	err = rsi_issue_sdiocommand(pfunction,
+				    MMC_SELECT_CARD,
+				    (rca << 16),
+				    (MMC_RSP_R1 | MMC_CMD_AC),
+				    NULL);
+	if (err) {
+		rsi_dbg(ERR_ZONE, "%s: CMD7 failed : %d\n", __func__, err);
+		return;
+	}
+
+	/* Enable high speed */
+	if (card->host->caps & MMC_CAP_SD_HIGHSPEED) {
+		rsi_dbg(ERR_ZONE, "%s: Set high speed mode\n", __func__);
+		err = rsi_cmd52readbyte(card, SDIO_CCCR_SPEED, &cmd52_resp);
+		if (err) {
+			rsi_dbg(ERR_ZONE, "%s: CCCR speed reg read failed: %d\n",
+				__func__, err);
+			card->state &= ~MMC_STATE_HIGHSPEED;
+		} else {
+			err = rsi_cmd52writebyte(card,
+						 SDIO_CCCR_SPEED,
+						 (cmd52_resp | SDIO_SPEED_EHS));
+			if (err) {
+				rsi_dbg(ERR_ZONE,
+					"%s: CCR speed regwrite failed %d\n",
+					__func__, err);
+				return;
+			}
+			mmc_card_set_highspeed(card);
+			host->ios.timing = MMC_TIMING_SD_HS;
+			host->ops->set_ios(host, &host->ios);
+		}
+	}
+
+	/* Set clock */
+	if (mmc_card_highspeed(card))
+		clock = 50000000;
+	else
+		clock = card->cis.max_dtr;
+
+	if (clock > host->f_max)
+		clock = host->f_max;
+
+	host->ios.clock = clock;
+	host->ops->set_ios(host, &host->ios);
+
+	if (card->host->caps & MMC_CAP_4_BIT_DATA) {
+		/* CMD52: Set bus width & disable card detect resistor */
+		err = rsi_cmd52writebyte(card,
+					 SDIO_CCCR_IF,
+					 (SDIO_BUS_CD_DISABLE |
+					  SDIO_BUS_WIDTH_4BIT));
+		if (err) {
+			rsi_dbg(ERR_ZONE, "%s: Set bus mode failed : %d\n",
+				__func__, err);
+			return;
+		}
+		host->ios.bus_width = MMC_BUS_WIDTH_4;
+		host->ops->set_ios(host, &host->ios);
+	}
+	return;
+}
+
+/**
+ * This function sets the clock frequency
+ *
+ * @param  adapter Pointer to the adapter structure.
+ * @param  freq Clock frequency.
+ * @return 0 on success.
+ */
+static int rsi_setclock(struct rsi_hw *adapter, unsigned int freq)
+{
+	unsigned int clock;
+	struct mmc_host *host = adapter->pfunction->card->host;
+
+	clock = freq * 1000;
+	if (clock > host->f_max)
+		clock = host->f_max;
+	host->ios.clock = clock;
+	host->ops->set_ios(host, &host->ios);
+	return 0;
+}
+
+/**
+ * This function sets the host block length.
+ *
+ * @param  adapter Pointer to the adapter structure.
+ * @param  length Block length to be set.
+ * @return status: 0 on success, -1 on failure.
+ */
+static int rsi_setblocklength(struct rsi_hw *adapter, unsigned int length)
+{
+	int status;
+	rsi_dbg(INIT_ZONE, "%s: Setting the block length\n", __func__);
+
+	status = sdio_set_block_size(adapter->pfunction, length);
+	adapter->pfunction->max_blksize = 256;
+
+	rsi_dbg(INFO_ZONE,
+		"%s: Operational blk length is %d\n", __func__, length);
+	return status;
+}
+
+/**
+ * This function queries and sets the card's features.
+ *
+ * @param  adapter Pointer to the adapter structure.
+ * @return status: 0 on success, -1 on failure.
+ */
+static int rsi_setupcard(struct rsi_hw *adapter)
+{
+	int status = 0;
+
+	if (rsi_setclock(adapter, 50000)) {
+		rsi_dbg(INFO_ZONE,
+			"%s: Unsuccessful at setting clk\n", __func__);
+		return -1;
+	}
+
+	adapter->tx_blk_size = 256;
+	adapter->rx_blk_size = 256;
+	status = rsi_setblocklength(adapter, adapter->tx_blk_size);
+	if (status) {
+		rsi_dbg(ERR_ZONE,
+			"%s: Unable to set block length\n", __func__);
+	}
+	return status;
+}
+
+/**
+ * This function does the actual initialization of SDBUS slave registers.
+ *
+ * @param  adapter Pointer to the adapter structure.
+ * @return status: 0 on success, -1 on failure.
+ */
+static int rsi_init_sdio_slave_regs(struct rsi_hw *adapter)
+{
+	unsigned char function = 0;
+	unsigned char byte;
+	int status = 0;
+
+	if (adapter->next_read_delay) {
+		byte = adapter->next_read_delay;
+		status = rsi_write_register(adapter,
+					    function,
+					    SDIO_NXT_RD_DELAY2,
+					    &byte);
+		if (status) {
+			rsi_dbg(ERR_ZONE,
+				"%s: Failed to write SDIO_NXT_RD_DELAY2\n",
+				__func__);
+			return -1;
+		}
+	}
+
+	if (adapter->sdio_high_speed_enable) {
+		rsi_dbg(INIT_ZONE, "%s: Enabling SDIO High speed\n", __func__);
+		byte = 0x3;
+
+		status = rsi_write_register(adapter,
+					    function,
+					    SDIO_REG_HIGH_SPEED,
+					    &byte);
+		if (status) {
+			rsi_dbg(ERR_ZONE,
+				"%s: Failed to enable SDIO high speed\n",
+				__func__);
+			return -1;
+		}
+	}
+
+	/* This tells SDIO FIFO when to start read to host */
+	rsi_dbg(INIT_ZONE, "%s: Initialzing SDIO read start level\n", __func__);
+	byte = 0x24;
+
+	status = rsi_write_register(adapter,
+				    function,
+				    SDIO_READ_START_LVL,
+				    &byte);
+	if (status) {
+		rsi_dbg(ERR_ZONE,
+			"%s: Failed to write SDIO_READ_START_LVL\n", __func__);
+		return -1;
+	}
+
+	rsi_dbg(INIT_ZONE, "%s: Initialzing FIFO ctrl registers\n", __func__);
+	byte = (128 - 32);
+
+	status = rsi_write_register(adapter,
+				    function,
+				    SDIO_READ_FIFO_CTL,
+				    &byte);
+	if (status) {
+		rsi_dbg(ERR_ZONE,
+			"%s: Failed to write SDIO_READ_FIFO_CTL\n", __func__);
+		return -1;
+	}
+
+	byte = 32;
+	status = rsi_write_register(adapter,
+				    function,
+				    SDIO_WRITE_FIFO_CTL,
+				    &byte);
+	if (status) {
+		rsi_dbg(ERR_ZONE,
+			"%s: Failed to write SDIO_WRITE_FIFO_CTL\n", __func__);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int rsi_init_sdio_interface(struct rsi_hw *adapter,
+				   struct sdio_func *pfunction)
+{
+	int status = 0;
+	sdio_claim_host(pfunction);
+
+	pfunction->enable_timeout = 100;
+	status = sdio_enable_func(pfunction);
+	if (status) {
+		rsi_dbg(ERR_ZONE, "%s: Failed to enable interface\n", __func__);
+		sdio_release_host(pfunction);
+		return status;
+	}
+
+	rsi_dbg(INIT_ZONE, "%s: Enabled the interface\n", __func__);
+
+	adapter->pfunction = pfunction;
+	adapter->device = &pfunction->dev;
+
+	sdio_set_drvdata(pfunction, adapter);
+
+	status = rsi_setupcard(adapter);
+	if (status) {
+		rsi_dbg(ERR_ZONE, "%s: Failed to setup card\n", __func__);
+		goto fail;
+	}
+
+	rsi_dbg(INIT_ZONE, "%s: Setup card succesfully\n", __func__);
+
+	status = rsi_init_sdio_slave_regs(adapter);
+	if (status) {
+		rsi_dbg(ERR_ZONE, "%s: Failed to init slave regs\n", __func__);
+		goto fail;
+	}
+	sdio_release_host(pfunction);
+	return status;
+fail:
+	sdio_disable_func(pfunction);
+	sdio_release_host(pfunction);
+	return status;
+}
+
+/**
+ * This function registers the client driver's interrupt handler
+ * with the bus driver.
+ *
+ * @param  pfunction Pointer to the sdio_func structure.
+ * @param  interrupt_handler Pointer to the interrupt handler.
+ * @param  pContext Pointer to context of interrupt.
+ * @return None.
+ */
+static int rsi_request_interrupt_handler(struct sdio_func *pfunction,
+					 SD_INTERRUPT interrupt_handler)
+{
+	int status;
+
+	status = sdio_claim_irq(pfunction,
+				(sdio_irq_handler_t *)interrupt_handler);
+	if (status) {
+		rsi_dbg(ERR_ZONE, "%s: Failed to request IRQ %d\n", __func__,
+			status);
+	}
+	return status;
+}
+
+/**
+ * This function acks the interrupt received.
+ *
+ * @param  adapter Pointer to the adapter structure.
+ * @param  int_bit Interrupt bit to write into register.
+ * @return Void.
+ */
+void rsi_ack_interrupt(struct rsi_hw *adapter, unsigned char int_bit)
+{
+	int status;
+	status = rsi_write_register(adapter,
+				    1,
+				    (SDIO_FUN1_INTR_CLR_REG |
+				     SD_REQUEST_MASTER),
+				    &int_bit);
+	if (status)
+		rsi_dbg(ERR_ZONE, "%s: unable to send ack\n", __func__);
+	return;
+}
+
+/**
+ * This function reads one byte of information from a register.
+ *
+ * @param  adapter Pointer to the adapter structure.
+ * @param  addr Address of the register.
+ * @param  data Pointer to the data that stores the data read.
+ * @return 0 on success, -1 on failure.
+ */
+int rsi_read_register(struct rsi_hw *adapter,
+		      unsigned int addr,
+		      unsigned char *data)
+{
+	unsigned char fun_num = 0;
+	int status;
+
+	sdio_claim_host(adapter->pfunction);
+
+	if (fun_num == 0)
+		*data = sdio_f0_readb(adapter->pfunction, addr, &status);
+	else
+		*data = sdio_readb(adapter->pfunction, addr, &status);
+
+	sdio_release_host(adapter->pfunction);
+
+	if (status)
+		return -1;
+	else
+		return 0;
+}
+
+/**
+ * This function writes one byte of information into a register.
+ *
+ * @param  adapter Pointer to the adapter structure.
+ * @param  function Function Number.
+ * @param  addr Address of the register.
+ * @param  data Pointer to the data tha has to be written.
+ * @return 0 on success, -1 on failure.
+ */
+int rsi_write_register(struct rsi_hw *adapter,
+		       unsigned char function,
+		       unsigned int addr,
+		       unsigned char *data)
+{
+	int status = 0;
+
+	sdio_claim_host(adapter->pfunction);
+
+	if (function == 0)
+		sdio_f0_writeb(adapter->pfunction, *data, addr, &status);
+	else
+		sdio_writeb(adapter->pfunction, *data, addr, &status);
+
+	sdio_release_host(adapter->pfunction);
+
+	if (status)
+		return -1;
+	else
+		return 0;
+}
+
+/**
+ * This function read multiple bytes of information from the SD card.
+ *
+ * @param  adapter Pointer to the adapter structure.
+ * @param  addr Address of the register.
+ * @param  count Number of multiple bytes to be read.
+ * @param  data Pointer to the read data.
+ * @return 0 on success, -1 on failure.
+ */
+int rsi_read_register_multiple(struct rsi_hw *adapter,
+			       unsigned int addr,
+			       unsigned int count,
+			       unsigned char *data)
+{
+	unsigned int status;
+
+	sdio_claim_host(adapter->pfunction);
+
+	status =  sdio_readsb(adapter->pfunction, data, addr, count);
+
+	sdio_release_host(adapter->pfunction);
+
+	if (status != 0)
+		rsi_dbg(ERR_ZONE, "%s: Synch Cmd53 read failed\n", __func__);
+	return status;
+}
+
+/**
+ * This function writes multiple bytes of information to the SD card.
+ *
+ * @param  adapter Pointer to the adapter structure.
+ * @param  addr Address of the register.
+ * @param  Pointer to the data that has to be written.
+ * @param  count Number of multiple bytes to be written.
+ * @return 0 on success, -1 on failure.
+ */
+int rsi_write_register_multiple(struct rsi_hw *adapter,
+				unsigned int addr,
+				unsigned char *data,
+				unsigned int count)
+{
+	int status = 0;
+
+	if (adapter->stop_card_write == 2) {
+		rsi_dbg(ERR_ZONE, "%s: Stopping card writes\n", __func__);
+		return 0;
+	} else if (adapter->stop_card_write == 1) {
+		rsi_dbg(ERR_ZONE, "%s: Continue card writes\n", __func__);
+		adapter->stop_card_write++;
+	}
+
+	sdio_claim_host(adapter->pfunction);
+
+	status = sdio_writesb(adapter->pfunction, addr, data, count);
+
+	sdio_release_host(adapter->pfunction);
+
+	if (status) {
+		rsi_dbg(ERR_ZONE, "%s: Synch Cmd53 write failed %d\n",
+			__func__, status);
+		adapter->stop_card_write = 2;
+		rsi_print(ERR_ZONE, adapter->prev_desc, FRAME_DESC_SZ);
+	} else {
+		memcpy(adapter->prev_desc, data, FRAME_DESC_SZ);
+	}
+	return status;
+}
+
+/**
+ * This function writes the packet to the device.
+ *
+ * @param  adapter Pointer to the adapter structure.
+ * @param  pkt Pointer to the data to be written on to the device.
+ * @param  len length of the data to be written on to the device.
+ * @return 0 on success, -1 on failure.
+ */
+int rsi_host_intf_write_pkt(struct rsi_hw *adapter,
+			unsigned char *pkt,
+			unsigned int len)
+{
+	unsigned int block_size = adapter->tx_blk_size;
+	unsigned int num_blocks, address, length;
+	unsigned int queueno;
+	int status = 0;
+
+	queueno = ((pkt[1] >> 4) & 0xf);
+
+	if ((!len)  && (queueno == RSI_WIFI_DATA_Q)) {
+		rsi_dbg(ERR_ZONE, "%s: Wrong length\n", __func__);
+		return -1;
+	}
+
+	num_blocks = len / block_size;
+
+	if (len % block_size)
+		num_blocks++;
+
+	if ((cpu_to_le16(*(unsigned short *)pkt) < 14) &&
+	    (queueno == RSI_WIFI_DATA_Q)) {
+		rsi_dbg(ERR_ZONE, "%s:Small pkt sending@@@\n", __func__);
+		return -1;
+	}
+
+	address = (num_blocks * block_size | (queueno << 12));
+	length  = num_blocks * block_size;
+
+	status = rsi_write_register_multiple(adapter,
+					     address,
+					     (unsigned char *)pkt,
+					     length);
+	if (status) {
+		rsi_dbg(ERR_ZONE, "%s: Unable to write onto the card: %d\n",
+			__func__, status);
+	}
+	rsi_dbg(DATA_TX_ZONE, "%s: Successfully written onto card\n", __func__);
+	return status;
+}
+
+/**
+ * This function reads the packet from the SD card.
+ *
+ * @param  adapter Pointer to the adapter data structure.
+ * @param  pkt Pointer to the packet data to be read from the the device.
+ * @param  length Length of the data to be read from the device.
+ * @return 0 on success, -1 on failure.
+ */
+int rsi_host_intf_read_pkt(struct rsi_hw *adapter,
+			   unsigned char *pkt,
+			   unsigned int length)
+{
+	int status  = 0;
+
+	if (!length) {
+		rsi_dbg(ERR_ZONE, "%s: Pkt size is zero\n", __func__);
+		return status;
+	}
+
+	status = rsi_read_register_multiple(adapter,
+					    length,
+					    length, /*num of bytes*/
+					    (unsigned char *)pkt);
+
+	if (status) {
+		rsi_dbg(ERR_ZONE, "%s: Failed to read frame: %d\n", __func__,
+			status);
+	}
+	return status;
+}
+
+/**
+ * This function is called by kernel when the driver provided
+ * Vendor and device IDs are matched. All the initialization
+ * work is done here.
+ *
+ * @param  pfunction Pointer to the sdio_func structure.
+ * @param  id Pointer to sdio_device_id structure.
+ * @return 0 on success, 1 on failure.
+ */
+static int rsi_probe(struct sdio_func *pfunction,
+		     const struct sdio_device_id *id)
+{
+	struct rsi_hw *adapter;
+
+	rsi_dbg(INIT_ZONE, "%s: Init function called\n", __func__);
+
+	adapter = rsi_init_os_intf_ops();
+	if (!adapter) {
+		rsi_dbg(ERR_ZONE, "%s: Failed to init os intf ops\n",
+			__func__);
+		return 1;
+	}
+
+	if (rsi_init_sdio_interface(adapter, pfunction)) {
+		rsi_dbg(ERR_ZONE, "%s: Failed to init sdio interface\n",
+			__func__);
+		goto fail;
+	}
+
+	if (rsi_device_init(adapter->priv, 0)) {
+		rsi_dbg(ERR_ZONE, "%s: Failed in device init\n", __func__);
+		sdio_claim_host(pfunction);
+		sdio_disable_func(pfunction);
+		sdio_release_host(pfunction);
+		goto fail;
+	}
+
+	sdio_claim_host(pfunction);
+	if (rsi_request_interrupt_handler(pfunction,
+					  (SD_INTERRUPT)rsi_handle_interrupt)) {
+		sdio_release_host(pfunction);
+		goto fail;
+	}
+
+	sdio_release_host(pfunction);
+	rsi_dbg(INIT_ZONE, "%s: Registered Interrupt handler\n", __func__);
+
+	return 0;
+fail:
+	rsi_deinit_os_intf_ops(adapter);
+	rsi_dbg(ERR_ZONE, "%s: Failed in probe...Exiting\n", __func__);
+	return 1;
+}
+
+/**
+ * This function performs the reverse of the probe function.
+ *
+ * @param  pfunction Pointer to the sdio_func structure.
+ * @return void.
+ */
+static void rsi_disconnect(struct sdio_func *pfunction)
+{
+	struct rsi_hw *adapter = sdio_get_drvdata(pfunction);
+
+	if (!adapter)
+		return;
+
+	adapter->stop_card_write = 2;
+	rsi_device_deinit(adapter);
+
+	sdio_claim_host(pfunction);
+	sdio_release_irq(pfunction);
+	sdio_disable_func(pfunction);
+	rsi_deinit_os_intf_ops(adapter);
+	rsi_reset_card(pfunction);
+	sdio_release_host(pfunction);
+
+	return;
+}
+
+#ifdef CONFIG_PM
+static int rsi_suspend(struct device *dev)
+{
+	/* Not yet implemented */
+	return -ENOSYS;
+}
+
+static int rsi_resume(struct device *dev)
+{
+	/* Not yet implemented */
+	return -ENOSYS;
+}
+
+static const struct dev_pm_ops rsi_pm_ops = {
+	.suspend = rsi_suspend,
+	.resume = rsi_resume,
+};
+#endif
+
+static const struct sdio_device_id rsi_dev_table[] =  {
+	{ SDIO_DEVICE(0x303, 0x100) },
+	{ SDIO_DEVICE(0x041B, 0x0301) },
+	{ SDIO_DEVICE(0x041B, 0x0201) },
+	{ SDIO_DEVICE(0x041B, 0x9330) },
+	{ /* Blank */},
+};
+
+static struct sdio_driver rsi_driver = {
+	.name       = "RSI-SDIO WLAN",
+	.probe      = rsi_probe,
+	.remove     = rsi_disconnect,
+	.id_table   = rsi_dev_table,
+#ifdef CONFIG_PM
+	.drv = {
+		.pm = &rsi_pm_ops,
+	}
+#endif
+};
+
+/**
+ * This function registers the sdio module.
+ *
+ * @param  Void.
+ * @return 0 on success.
+ */
+static int rsi_module_init(void)
+{
+	sdio_register_driver(&rsi_driver);
+	rsi_dbg(INIT_ZONE, "%s: Registering driver\n", __func__);
+	return 0;
+}
+
+/**
+ * This function unregisters the sdio module.
+ *
+ * @param  Void.
+ * @return None.
+ */
+static void rsi_module_exit(void)
+{
+	sdio_unregister_driver(&rsi_driver);
+	rsi_dbg(INFO_ZONE, "%s: Unregistering driver\n", __func__);
+	return;
+}
+
+module_init(rsi_module_init);
+module_exit(rsi_module_exit);
+
+MODULE_AUTHOR("Redpine Signals Inc");
+MODULE_DESCRIPTION("Common layer for RSI drivers");
+MODULE_SUPPORTED_DEVICE("RSI-91x");
+MODULE_VERSION("0.1");
+MODULE_LICENSE("GPL");