libertas: if_spi, driver for libertas GSPI devices

Add initial support for libertas devices using a GSPI interface.  This has
been tested with the 8686.

GSPI is intended to be used on embedded systems. Board-specific parameters are
required (see libertas_spi.h).

Thanks to everyone who took a look at the earlier versions of the patch.

Signed-off-by: Colin McCabe <colin@cozybit.com>
Signed-off-by: Andrey Yurovsky <andrey@cozybit.com>
Acked-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 1203 insertions, 0 deletions

diff --git a/drivers/net/wireless/libertas/if_spi.c b/drivers/net/wireless/libertas/if_spi.c
new file mode 100644
index 0000000..7c02ea3
--- /dev/null
+++ b/drivers/net/wireless/libertas/if_spi.c
@@ -0,0 +1,1203 @@
+/*
+ *	linux/drivers/net/wireless/libertas/if_spi.c
+ *
+ *	Driver for Marvell SPI WLAN cards.
+ *
+ *	Copyright 2008 Analog Devices Inc.
+ *
+ *	Authors:
+ *	Andrey Yurovsky <andrey@cozybit.com>
+ *	Colin McCabe <colin@cozybit.com>
+ *
+ *	Inspired by if_sdio.c, Copyright 2007-2008 Pierre Ossman
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/moduleparam.h>
+#include <linux/firmware.h>
+#include <linux/gpio.h>
+#include <linux/jiffies.h>
+#include <linux/kthread.h>
+#include <linux/list.h>
+#include <linux/netdevice.h>
+#include <linux/spi/libertas_spi.h>
+#include <linux/spi/spi.h>
+
+#include "host.h"
+#include "decl.h"
+#include "defs.h"
+#include "dev.h"
+#include "if_spi.h"
+
+struct if_spi_packet {
+	struct list_head		list;
+	u16				blen;
+	u8				buffer[0] __attribute__((aligned(4)));
+};
+
+struct if_spi_card {
+	struct spi_device		*spi;
+	struct lbs_private		*priv;
+
+	char				helper_fw_name[FIRMWARE_NAME_MAX];
+	char				main_fw_name[FIRMWARE_NAME_MAX];
+
+	/* The card ID and card revision, as reported by the hardware. */
+	u16				card_id;
+	u8				card_rev;
+
+	/* Pin number for our GPIO chip-select. */
+	/* TODO: Once the generic SPI layer has some additional features, we
+	 * should take this out and use the normal chip select here.
+	 * We need support for chip select delays, and not dropping chipselect
+	 * after each word. */
+	int				gpio_cs;
+
+	/* The last time that we initiated an SPU operation */
+	unsigned long			prev_xfer_time;
+
+	int				use_dummy_writes;
+	unsigned long			spu_port_delay;
+	unsigned long			spu_reg_delay;
+
+	/* Handles all SPI communication (except for FW load) */
+	struct task_struct		*spi_thread;
+	int				run_thread;
+
+	/* Used to wake up the spi_thread */
+	struct semaphore		spi_ready;
+	struct semaphore		spi_thread_terminated;
+
+	u8				cmd_buffer[IF_SPI_CMD_BUF_SIZE];
+
+	/* A buffer of incoming packets from libertas core.
+	 * Since we can't sleep in hw_host_to_card, we have to buffer
+	 * them. */
+	struct list_head		cmd_packet_list;
+	struct list_head		data_packet_list;
+
+	/* Protects cmd_packet_list and data_packet_list */
+	spinlock_t			buffer_lock;
+};
+
+static void free_if_spi_card(struct if_spi_card *card)
+{
+	struct list_head *cursor, *next;
+	struct if_spi_packet *packet;
+
+	BUG_ON(card->run_thread);
+	list_for_each_safe(cursor, next, &card->cmd_packet_list) {
+		packet = container_of(cursor, struct if_spi_packet, list);
+		list_del(&packet->list);
+		kfree(packet);
+	}
+	list_for_each_safe(cursor, next, &card->data_packet_list) {
+		packet = container_of(cursor, struct if_spi_packet, list);
+		list_del(&packet->list);
+		kfree(packet);
+	}
+	spi_set_drvdata(card->spi, NULL);
+	kfree(card);
+}
+
+static struct chip_ident chip_id_to_device_name[] = {
+	{ .chip_id = 0x04, .name = 8385 },
+	{ .chip_id = 0x0b, .name = 8686 },
+};
+
+/*
+ * SPI Interface Unit Routines
+ *
+ * The SPU sits between the host and the WLAN module.
+ * All communication with the firmware is through SPU transactions.
+ *
+ * First we have to put a SPU register name on the bus. Then we can
+ * either read from or write to that register.
+ *
+ * For 16-bit transactions, byte order on the bus is big-endian.
+ * We don't have to worry about that here, though.
+ * The translation takes place in the SPI routines.
+ */
+
+static void spu_transaction_init(struct if_spi_card *card)
+{
+	if (!time_after(jiffies, card->prev_xfer_time + 1)) {
+		/* Unfortunately, the SPU requires a delay between successive
+		 * transactions. If our last transaction was more than a jiffy
+		 * ago, we have obviously already delayed enough.
+		 * If not, we have to busy-wait to be on the safe side. */
+		ndelay(400);
+	}
+	gpio_set_value(card->gpio_cs, 0); /* assert CS */
+}
+
+static void spu_transaction_finish(struct if_spi_card *card)
+{
+	gpio_set_value(card->gpio_cs, 1); /* drop CS */
+	card->prev_xfer_time = jiffies;
+}
+
+/* Write out a byte buffer to an SPI register,
+ * using a series of 16-bit transfers. */
+static int spu_write(struct if_spi_card *card, u16 reg, const u8 *buf, int len)
+{
+	int err = 0;
+	u16 reg_out = reg | IF_SPI_WRITE_OPERATION_MASK;
+
+	/* You must give an even number of bytes to the SPU, even if it
+	 * doesn't care about the last one.  */
+	BUG_ON(len & 0x1);
+
+	spu_transaction_init(card);
+
+	/* write SPU register index */
+	err = spi_write(card->spi, (u8 *)&reg_out, sizeof(u16));
+	if (err)
+		goto out;
+
+	err = spi_write(card->spi, buf, len);
+
+out:
+	spu_transaction_finish(card);
+	return err;
+}
+
+static inline int spu_write_u16(struct if_spi_card *card, u16 reg, u16 val)
+{
+	return spu_write(card, reg, (u8 *)&val, sizeof(u16));
+}
+
+static inline int spu_write_u32(struct if_spi_card *card, u16 reg, u32 val)
+{
+	/* The lower 16 bits are written first. */
+	u16 out[2];
+	out[0] = val & 0xffff;
+	out[1] = (val & 0xffff0000) >> 16;
+	return spu_write(card, reg, (u8 *)&out, sizeof(u32));
+}
+
+static inline int spu_reg_is_port_reg(u16 reg)
+{
+	switch (reg) {
+	case IF_SPI_IO_RDWRPORT_REG:
+	case IF_SPI_CMD_RDWRPORT_REG:
+	case IF_SPI_DATA_RDWRPORT_REG:
+		return 1;
+	default:
+		return 0;
+	}
+}
+
+static int spu_read(struct if_spi_card *card, u16 reg, u8 *buf, int len)
+{
+	unsigned int i, delay;
+	int err = 0;
+	u16 zero = 0;
+	u16 reg_out = reg | IF_SPI_READ_OPERATION_MASK;
+
+	/* You must take an even number of bytes from the SPU, even if you
+	 * don't care about the last one.  */
+	BUG_ON(len & 0x1);
+
+	spu_transaction_init(card);
+
+	/* write SPU register index */
+	err = spi_write(card->spi, (u8 *)&reg_out, sizeof(u16));
+	if (err)
+		goto out;
+
+	delay = spu_reg_is_port_reg(reg) ? card->spu_port_delay :
+						card->spu_reg_delay;
+	if (card->use_dummy_writes) {
+		/* Clock in dummy cycles while the SPU fills the FIFO */
+		for (i = 0; i < delay / 16; ++i) {
+			err = spi_write(card->spi, (u8 *)&zero, sizeof(u16));
+			if (err)
+				return err;
+		}
+	} else {
+		/* Busy-wait while the SPU fills the FIFO */
+		ndelay(100 + (delay * 10));
+	}
+
+	/* read in data */
+	err = spi_read(card->spi, buf, len);
+
+out:
+	spu_transaction_finish(card);
+	return err;
+}
+
+/* Read 16 bits from an SPI register */
+static inline int spu_read_u16(struct if_spi_card *card, u16 reg, u16 *val)
+{
+	return spu_read(card, reg, (u8 *)val, sizeof(u16));
+}
+
+/* Read 32 bits from an SPI register.
+ * The low 16 bits are read first. */
+static int spu_read_u32(struct if_spi_card *card, u16 reg, u32 *val)
+{
+	u16 buf[2];
+	int err;
+	err = spu_read(card, reg, (u8 *)buf, sizeof(u32));
+	if (!err)
+		*val = buf[0] | (buf[1] << 16);
+	return err;
+}
+
+/* Keep reading 16 bits from an SPI register until you get the correct result.
+ *
+ * If mask = 0, the correct result is any non-zero number.
+ * If mask != 0, the correct result is any number where
+ * number & target_mask == target
+ *
+ * Returns -ETIMEDOUT if a second passes without the correct result. */
+static int spu_wait_for_u16(struct if_spi_card *card, u16 reg,
+			u16 target_mask, u16 target)
+{
+	int err;
+	unsigned long timeout = jiffies + 5*HZ;
+	while (1) {
+		u16 val;
+		err = spu_read_u16(card, reg, &val);
+		if (err)
+			return err;
+		if (target_mask) {
+			if ((val & target_mask) == target)
+				return 0;
+		} else {
+			if (val)
+				return 0;
+		}
+		udelay(100);
+		if (time_after(jiffies, timeout)) {
+			lbs_pr_err("%s: timeout with val=%02x, "
+			       "target_mask=%02x, target=%02x\n",
+			       __func__, val, target_mask, target);
+			return -ETIMEDOUT;
+		}
+	}
+}
+
+/* Read 16 bits from an SPI register until you receive a specific value.
+ * Returns -ETIMEDOUT if a 4 tries pass without success. */
+static int spu_wait_for_u32(struct if_spi_card *card, u32 reg, u32 target)
+{
+	int err, try;
+	for (try = 0; try < 4; ++try) {
+		u32 val = 0;
+		err = spu_read_u32(card, reg, &val);
+		if (err)
+			return err;
+		if (val == target)
+			return 0;
+		mdelay(100);
+	}
+	return -ETIMEDOUT;
+}
+
+static int spu_set_interrupt_mode(struct if_spi_card *card,
+			   int suppress_host_int,
+			   int auto_int)
+{
+	int err = 0;
+
+	/* We can suppress a host interrupt by clearing the appropriate
+	 * bit in the "host interrupt status mask" register */
+	if (suppress_host_int) {
+		err = spu_write_u16(card, IF_SPI_HOST_INT_STATUS_MASK_REG, 0);
+		if (err)
+			return err;
+	} else {
+		err = spu_write_u16(card, IF_SPI_HOST_INT_STATUS_MASK_REG,
+			      IF_SPI_HISM_TX_DOWNLOAD_RDY |
+			      IF_SPI_HISM_RX_UPLOAD_RDY |
+			      IF_SPI_HISM_CMD_DOWNLOAD_RDY |
+			      IF_SPI_HISM_CARDEVENT |
+			      IF_SPI_HISM_CMD_UPLOAD_RDY);
+		if (err)
+			return err;
+	}
+
+	/* If auto-interrupts are on, the completion of certain transactions
+	 * will trigger an interrupt automatically. If auto-interrupts
+	 * are off, we need to set the "Card Interrupt Cause" register to
+	 * trigger a card interrupt. */
+	if (auto_int) {
+		err = spu_write_u16(card, IF_SPI_HOST_INT_CTRL_REG,
+				IF_SPI_HICT_TX_DOWNLOAD_OVER_AUTO |
+				IF_SPI_HICT_RX_UPLOAD_OVER_AUTO |
+				IF_SPI_HICT_CMD_DOWNLOAD_OVER_AUTO |
+				IF_SPI_HICT_CMD_UPLOAD_OVER_AUTO);
+		if (err)
+			return err;
+	} else {
+		err = spu_write_u16(card, IF_SPI_HOST_INT_STATUS_MASK_REG, 0);
+		if (err)
+			return err;
+	}
+	return err;
+}
+
+static int spu_get_chip_revision(struct if_spi_card *card,
+				  u16 *card_id, u8 *card_rev)
+{
+	int err = 0;
+	u32 dev_ctrl;
+	err = spu_read_u32(card, IF_SPI_DEVICEID_CTRL_REG, &dev_ctrl);
+	if (err)
+		return err;
+	*card_id = IF_SPI_DEVICEID_CTRL_REG_TO_CARD_ID(dev_ctrl);
+	*card_rev = IF_SPI_DEVICEID_CTRL_REG_TO_CARD_REV(dev_ctrl);
+	return err;
+}
+
+static int spu_set_bus_mode(struct if_spi_card *card, u16 mode)
+{
+	int err = 0;
+	u16 rval;
+	/* set bus mode */
+	err = spu_write_u16(card, IF_SPI_SPU_BUS_MODE_REG, mode);
+	if (err)
+		return err;
+	/* Check that we were able to read back what we just wrote. */
+	err = spu_read_u16(card, IF_SPI_SPU_BUS_MODE_REG, &rval);
+	if (err)
+		return err;
+	if (rval != mode) {
+		lbs_pr_err("Can't read bus mode register.\n");
+		return -EIO;
+	}
+	return 0;
+}
+
+static int spu_init(struct if_spi_card *card, int use_dummy_writes)
+{
+	int err = 0;
+	u32 delay;
+
+	/* We have to start up in timed delay mode so that we can safely
+	 * read the Delay Read Register. */
+	card->use_dummy_writes = 0;
+	err = spu_set_bus_mode(card,
+				IF_SPI_BUS_MODE_SPI_CLOCK_PHASE_RISING |
+				IF_SPI_BUS_MODE_DELAY_METHOD_TIMED |
+				IF_SPI_BUS_MODE_16_BIT_ADDRESS_16_BIT_DATA);
+	if (err)
+		return err;
+	card->spu_port_delay = 1000;
+	card->spu_reg_delay = 1000;
+	err = spu_read_u32(card, IF_SPI_DELAY_READ_REG, &delay);
+	if (err)
+		return err;
+	card->spu_port_delay = delay & 0x0000ffff;
+	card->spu_reg_delay = (delay & 0xffff0000) >> 16;
+
+	/* If dummy clock delay mode has been requested, switch to it now */
+	if (use_dummy_writes) {
+		card->use_dummy_writes = 1;
+		err = spu_set_bus_mode(card,
+				IF_SPI_BUS_MODE_SPI_CLOCK_PHASE_RISING |
+				IF_SPI_BUS_MODE_DELAY_METHOD_DUMMY_CLOCK |
+				IF_SPI_BUS_MODE_16_BIT_ADDRESS_16_BIT_DATA);
+		if (err)
+			return err;
+	}
+
+	lbs_deb_spi("Initialized SPU unit. "
+		    "spu_port_delay=0x%04lx, spu_reg_delay=0x%04lx\n",
+		    card->spu_port_delay, card->spu_reg_delay);
+	return err;
+}
+
+/*
+ * Firmware Loading
+ */
+
+static int if_spi_prog_helper_firmware(struct if_spi_card *card)
+{
+	int err = 0;
+	const struct firmware *firmware = NULL;
+	int bytes_remaining;
+	const u8 *fw;
+	u8 temp[HELPER_FW_LOAD_CHUNK_SZ];
+	struct spi_device *spi = card->spi;
+
+	lbs_deb_enter(LBS_DEB_SPI);
+
+	err = spu_set_interrupt_mode(card, 1, 0);
+	if (err)
+		goto out;
+	/* Get helper firmware image */
+	err = request_firmware(&firmware, card->helper_fw_name, &spi->dev);
+	if (err) {
+		lbs_pr_err("request_firmware failed with err = %d\n", err);
+		goto out;
+	}
+	bytes_remaining = firmware->size;
+	fw = firmware->data;
+
+	/* Load helper firmware image */
+	while (bytes_remaining > 0) {
+		/* Scratch pad 1 should contain the number of bytes we
+		 * want to download to the firmware */
+		err = spu_write_u16(card, IF_SPI_SCRATCH_1_REG,
+					HELPER_FW_LOAD_CHUNK_SZ);
+		if (err)
+			goto release_firmware;
+
+		err = spu_wait_for_u16(card, IF_SPI_HOST_INT_STATUS_REG,
+					IF_SPI_HIST_CMD_DOWNLOAD_RDY,
+					IF_SPI_HIST_CMD_DOWNLOAD_RDY);
+		if (err)
+			goto release_firmware;
+
+		/* Feed the data into the command read/write port reg
+		 * in chunks of 64 bytes */
+		memset(temp, 0, sizeof(temp));
+		memcpy(temp, fw,
+		       min(bytes_remaining, HELPER_FW_LOAD_CHUNK_SZ));
+		mdelay(10);
+		err = spu_write(card, IF_SPI_CMD_RDWRPORT_REG,
+					temp, HELPER_FW_LOAD_CHUNK_SZ);
+		if (err)
+			goto release_firmware;
+
+		/* Interrupt the boot code */
+		err = spu_write_u16(card, IF_SPI_HOST_INT_STATUS_REG, 0);
+		if (err)
+			goto release_firmware;
+		err = spu_write_u16(card, IF_SPI_CARD_INT_CAUSE_REG,
+				       IF_SPI_CIC_CMD_DOWNLOAD_OVER);
+		if (err)
+			goto release_firmware;
+		bytes_remaining -= HELPER_FW_LOAD_CHUNK_SZ;
+		fw += HELPER_FW_LOAD_CHUNK_SZ;
+	}
+
+	/* Once the helper / single stage firmware download is complete,
+	 * write 0 to scratch pad 1 and interrupt the
+	 * bootloader. This completes the helper download. */
+	err = spu_write_u16(card, IF_SPI_SCRATCH_1_REG, FIRMWARE_DNLD_OK);
+	if (err)
+		goto release_firmware;
+	err = spu_write_u16(card, IF_SPI_HOST_INT_STATUS_REG, 0);
+	if (err)
+		goto release_firmware;
+	err = spu_write_u16(card, IF_SPI_CARD_INT_CAUSE_REG,
+				IF_SPI_CIC_CMD_DOWNLOAD_OVER);
+		goto release_firmware;
+
+	lbs_deb_spi("waiting for helper to boot...\n");
+
+release_firmware:
+	release_firmware(firmware);
+out:
+	if (err)
+		lbs_pr_err("failed to load helper firmware (err=%d)\n", err);
+	lbs_deb_leave_args(LBS_DEB_SPI, "err %d", err);
+	return err;
+}
+
+/* Returns the length of the next packet the firmware expects us to send
+ * Sets crc_err if the previous transfer had a CRC error. */
+static int if_spi_prog_main_firmware_check_len(struct if_spi_card *card,
+						int *crc_err)
+{
+	u16 len;
+	int err = 0;
+
+	/* wait until the host interrupt status register indicates
+	 * that we are ready to download */
+	err = spu_wait_for_u16(card, IF_SPI_HOST_INT_STATUS_REG,
+				IF_SPI_HIST_CMD_DOWNLOAD_RDY,
+				IF_SPI_HIST_CMD_DOWNLOAD_RDY);
+	if (err) {
+		lbs_pr_err("timed out waiting for host_int_status\n");
+		return err;
+	}
+
+	/* Ask the device how many bytes of firmware it wants. */
+	err = spu_read_u16(card, IF_SPI_SCRATCH_1_REG, &len);
+	if (err)
+		return err;
+
+	if (len > IF_SPI_CMD_BUF_SIZE) {
+		lbs_pr_err("firmware load device requested a larger "
+			   "tranfer than we are prepared to "
+			   "handle. (len = %d)\n", len);
+		return -EIO;
+	}
+	if (len & 0x1) {
+		lbs_deb_spi("%s: crc error\n", __func__);
+		len &= ~0x1;
+		*crc_err = 1;
+	} else
+		*crc_err = 0;
+
+	return len;
+}
+
+static int if_spi_prog_main_firmware(struct if_spi_card *card)
+{
+	int len, prev_len;
+	int bytes, crc_err = 0, err = 0;
+	const struct firmware *firmware = NULL;
+	const u8 *fw;
+	struct spi_device *spi = card->spi;
+	u16 num_crc_errs;
+
+	lbs_deb_enter(LBS_DEB_SPI);
+
+	err = spu_set_interrupt_mode(card, 1, 0);
+	if (err)
+		goto out;
+
+	/* Get firmware image */
+	err = request_firmware(&firmware, card->main_fw_name, &spi->dev);
+	if (err) {
+		lbs_pr_err("%s: can't get firmware '%s' from kernel. "
+			"err = %d\n", __func__, card->main_fw_name, err);
+		goto out;
+	}
+
+	err = spu_wait_for_u16(card, IF_SPI_SCRATCH_1_REG, 0, 0);
+	if (err) {
+		lbs_pr_err("%s: timed out waiting for initial "
+			   "scratch reg = 0\n", __func__);
+		goto release_firmware;
+	}
+
+	num_crc_errs = 0;
+	prev_len = 0;
+	bytes = firmware->size;
+	fw = firmware->data;
+	while ((len = if_spi_prog_main_firmware_check_len(card, &crc_err))) {
+		if (len < 0) {
+			err = len;
+			goto release_firmware;
+		}
+		if (bytes < 0) {
+			/* If there are no more bytes left, we would normally
+			 * expect to have terminated with len = 0 */
+			lbs_pr_err("Firmware load wants more bytes "
+				   "than we have to offer.\n");
+			break;
+		}
+		if (crc_err) {
+			/* Previous transfer failed. */
+			if (++num_crc_errs > MAX_MAIN_FW_LOAD_CRC_ERR) {
+				lbs_pr_err("Too many CRC errors encountered "
+					   "in firmware load.\n");
+				err = -EIO;
+				goto release_firmware;
+			}
+		} else {
+			/* Previous transfer succeeded. Advance counters. */
+			bytes -= prev_len;
+			fw += prev_len;
+		}
+		if (bytes < len) {
+			memset(card->cmd_buffer, 0, len);
+			memcpy(card->cmd_buffer, fw, bytes);
+		} else
+			memcpy(card->cmd_buffer, fw, len);
+
+		err = spu_write_u16(card, IF_SPI_HOST_INT_STATUS_REG, 0);
+		if (err)
+			goto release_firmware;
+		err = spu_write(card, IF_SPI_CMD_RDWRPORT_REG,
+				card->cmd_buffer, len);
+		if (err)
+			goto release_firmware;
+		err = spu_write_u16(card, IF_SPI_CARD_INT_CAUSE_REG ,
+					IF_SPI_CIC_CMD_DOWNLOAD_OVER);
+		if (err)
+			goto release_firmware;
+		prev_len = len;
+	}
+	if (bytes > prev_len) {
+		lbs_pr_err("firmware load wants fewer bytes than "
+			   "we have to offer.\n");
+	}
+
+	/* Confirm firmware download */
+	err = spu_wait_for_u32(card, IF_SPI_SCRATCH_4_REG,
+					SUCCESSFUL_FW_DOWNLOAD_MAGIC);
+	if (err) {
+		lbs_pr_err("failed to confirm the firmware download\n");
+		goto release_firmware;
+	}
+
+release_firmware:
+	release_firmware(firmware);
+
+out:
+	if (err)
+		lbs_pr_err("failed to load firmware (err=%d)\n", err);
+	lbs_deb_leave_args(LBS_DEB_SPI, "err %d", err);
+	return err;
+}
+
+/*
+ * SPI Transfer Thread
+ *
+ * The SPI thread handles all SPI transfers, so there is no need for a lock.
+ */
+
+/* Move a command from the card to the host */
+static int if_spi_c2h_cmd(struct if_spi_card *card)
+{
+	struct lbs_private *priv = card->priv;
+	unsigned long flags;
+	int err = 0;
+	u16 len;
+	u8 i;
+
+	/* We need a buffer big enough to handle whatever people send to
+	 * hw_host_to_card */
+	BUILD_BUG_ON(IF_SPI_CMD_BUF_SIZE < LBS_CMD_BUFFER_SIZE);
+	BUILD_BUG_ON(IF_SPI_CMD_BUF_SIZE < LBS_UPLD_SIZE);
+
+	/* It's just annoying if the buffer size isn't a multiple of 4, because
+	 * then we might have len <  IF_SPI_CMD_BUF_SIZE but
+	 * ALIGN(len, 4) > IF_SPI_CMD_BUF_SIZE */
+	BUILD_BUG_ON(IF_SPI_CMD_BUF_SIZE % 4 != 0);
+
+	lbs_deb_enter(LBS_DEB_SPI);
+
+	/* How many bytes are there to read? */
+	err = spu_read_u16(card, IF_SPI_SCRATCH_2_REG, &len);
+	if (err)
+		goto out;
+	if (!len) {
+		lbs_pr_err("%s: error: card has no data for host\n",
+			   __func__);
+		err = -EINVAL;
+		goto out;
+	} else if (len > IF_SPI_CMD_BUF_SIZE) {
+		lbs_pr_err("%s: error: response packet too large: "
+			   "%d bytes, but maximum is %d\n",
+			   __func__, len, IF_SPI_CMD_BUF_SIZE);
+		err = -EINVAL;
+		goto out;
+	}
+
+	/* Read the data from the WLAN module into our command buffer */
+	err = spu_read(card, IF_SPI_CMD_RDWRPORT_REG,
+				card->cmd_buffer, ALIGN(len, 4));
+	if (err)
+		goto out;
+
+	spin_lock_irqsave(&priv->driver_lock, flags);
+	i = (priv->resp_idx == 0) ? 1 : 0;
+	BUG_ON(priv->resp_len[i]);
+	priv->resp_len[i] = len;
+	memcpy(priv->resp_buf[i], card->cmd_buffer, len);
+	lbs_notify_command_response(priv, i);
+	spin_unlock_irqrestore(&priv->driver_lock, flags);
+
+out:
+	if (err)
+		lbs_pr_err("%s: err=%d\n", __func__, err);
+	lbs_deb_leave(LBS_DEB_SPI);
+	return err;
+}
+
+/* Move data from the card to the host */
+static int if_spi_c2h_data(struct if_spi_card *card)
+{
+	struct sk_buff *skb;
+	char *data;
+	u16 len;
+	int err = 0;
+
+	lbs_deb_enter(LBS_DEB_SPI);
+
+	/* How many bytes are there to read? */
+	err = spu_read_u16(card, IF_SPI_SCRATCH_1_REG, &len);
+	if (err)
+		goto out;
+	if (!len) {
+		lbs_pr_err("%s: error: card has no data for host\n",
+			   __func__);
+		err = -EINVAL;
+		goto out;
+	} else if (len > MRVDRV_ETH_RX_PACKET_BUFFER_SIZE) {
+		lbs_pr_err("%s: error: card has %d bytes of data, but "
+			   "our maximum skb size is %u\n",
+			   __func__, len, MRVDRV_ETH_RX_PACKET_BUFFER_SIZE);
+		err = -EINVAL;
+		goto out;
+	}
+
+	/* TODO: should we allocate a smaller skb if we have less data? */
+	skb = dev_alloc_skb(MRVDRV_ETH_RX_PACKET_BUFFER_SIZE);
+	if (!skb) {
+		err = -ENOBUFS;
+		goto out;
+	}
+	skb_reserve(skb, IPFIELD_ALIGN_OFFSET);
+	data = skb_put(skb, len);
+
+	/* Read the data from the WLAN module into our skb... */
+	err = spu_read(card, IF_SPI_DATA_RDWRPORT_REG, data, ALIGN(len, 4));
+	if (err)
+		goto free_skb;
+
+	/* pass the SKB to libertas */
+	err = lbs_process_rxed_packet(card->priv, skb);
+	if (err)
+		goto free_skb;
+
+	/* success */
+	goto out;
+
+free_skb:
+	dev_kfree_skb(skb);
+out:
+	if (err)
+		lbs_pr_err("%s: err=%d\n", __func__, err);
+	lbs_deb_leave(LBS_DEB_SPI);
+	return err;
+}
+
+/* Move data or a command from the host to the card. */
+static void if_spi_h2c(struct if_spi_card *card,
+			struct if_spi_packet *packet, int type)
+{
+	int err = 0;
+	u16 int_type, port_reg;
+
+	switch (type) {
+	case MVMS_DAT:
+		int_type = IF_SPI_CIC_TX_DOWNLOAD_OVER;
+		port_reg = IF_SPI_DATA_RDWRPORT_REG;
+		break;
+	case MVMS_CMD:
+		int_type = IF_SPI_CIC_CMD_DOWNLOAD_OVER;
+		port_reg = IF_SPI_CMD_RDWRPORT_REG;
+		break;
+	default:
+		lbs_pr_err("can't transfer buffer of type %d\n", type);
+		err = -EINVAL;
+		goto out;
+	}
+
+	/* Write the data to the card */
+	err = spu_write(card, port_reg, packet->buffer, packet->blen);
+	if (err)
+		goto out;
+
+out:
+	kfree(packet);
+
+	if (err)
+		lbs_pr_err("%s: error %d\n", __func__, err);
+}
+
+/* Inform the host about a card event */
+static void if_spi_e2h(struct if_spi_card *card)
+{
+	int err = 0;
+	unsigned long flags;
+	u32 cause;
+	struct lbs_private *priv = card->priv;
+
+	err = spu_read_u32(card, IF_SPI_SCRATCH_3_REG, &cause);
+	if (err)
+		goto out;
+
+	spin_lock_irqsave(&priv->driver_lock, flags);
+	lbs_queue_event(priv, cause & 0xff);
+	spin_unlock_irqrestore(&priv->driver_lock, flags);
+
+out:
+	if (err)
+		lbs_pr_err("%s: error %d\n", __func__, err);
+}
+
+static int lbs_spi_thread(void *data)
+{
+	int err;
+	struct if_spi_card *card = data;
+	u16 hiStatus;
+	unsigned long flags;
+	struct if_spi_packet *packet;
+
+	while (1) {
+		/* Wait to be woken up by one of two things.  First, our ISR
+		 * could tell us that something happened on the WLAN.
+		 * Secondly, libertas could call hw_host_to_card with more
+		 * data, which we might be able to send.
+		 */
+		do {
+			err = down_interruptible(&card->spi_ready);
+			if (!card->run_thread) {
+				up(&card->spi_thread_terminated);
+				do_exit(0);
+			}
+		} while (err == EINTR);
+
+		/* Read the host interrupt status register to see what we
+		 * can do. */
+		err = spu_read_u16(card, IF_SPI_HOST_INT_STATUS_REG,
+					&hiStatus);
+		if (err) {
+			lbs_pr_err("I/O error\n");
+			goto err;
+		}
+
+		if (hiStatus & IF_SPI_HIST_CMD_UPLOAD_RDY)
+			err = if_spi_c2h_cmd(card);
+			if (err)
+				goto err;
+		if (hiStatus & IF_SPI_HIST_RX_UPLOAD_RDY)
+			err = if_spi_c2h_data(card);
+			if (err)
+				goto err;
+		if (hiStatus & IF_SPI_HIST_CMD_DOWNLOAD_RDY) {
+			/* This means two things. First of all,
+			 * if there was a previous command sent, the card has
+			 * successfully received it.
+			 * Secondly, it is now ready to download another
+			 * command.
+			 */
+			lbs_host_to_card_done(card->priv);
+
+			/* Do we have any command packets from the host to
+			 * send? */
+			packet = NULL;
+			spin_lock_irqsave(&card->buffer_lock, flags);
+			if (!list_empty(&card->cmd_packet_list)) {
+				packet = (struct if_spi_packet *)(card->
+						cmd_packet_list.next);
+				list_del(&packet->list);
+			}
+			spin_unlock_irqrestore(&card->buffer_lock, flags);
+
+			if (packet)
+				if_spi_h2c(card, packet, MVMS_CMD);
+		}
+		if (hiStatus & IF_SPI_HIST_TX_DOWNLOAD_RDY) {
+			/* Do we have any data packets from the host to
+			 * send? */
+			packet = NULL;
+			spin_lock_irqsave(&card->buffer_lock, flags);
+			if (!list_empty(&card->data_packet_list)) {
+				packet = (struct if_spi_packet *)(card->
+						data_packet_list.next);
+				list_del(&packet->list);
+			}
+			spin_unlock_irqrestore(&card->buffer_lock, flags);
+
+			if (packet)
+				if_spi_h2c(card, packet, MVMS_DAT);
+		}
+		if (hiStatus & IF_SPI_HIST_CARD_EVENT)
+			if_spi_e2h(card);
+
+err:
+		if (err)
+			lbs_pr_err("%s: got error %d\n", __func__, err);
+	}
+}
+
+/* Block until lbs_spi_thread thread has terminated */
+static void if_spi_terminate_spi_thread(struct if_spi_card *card)
+{
+	/* It would be nice to use kthread_stop here, but that function
+	 * can't wake threads waiting for a semaphore. */
+	card->run_thread = 0;
+	up(&card->spi_ready);
+	down(&card->spi_thread_terminated);
+}
+
+/*
+ * Host to Card
+ *
+ * Called from Libertas to transfer some data to the WLAN device
+ * We can't sleep here. */
+static int if_spi_host_to_card(struct lbs_private *priv,
+				u8 type, u8 *buf, u16 nb)
+{
+	int err = 0;
+	unsigned long flags;
+	struct if_spi_card *card = priv->card;
+	struct if_spi_packet *packet;
+	u16 blen;
+
+	lbs_deb_enter_args(LBS_DEB_SPI, "type %d, bytes %d", type, nb);
+
+	if (nb == 0) {
+		lbs_pr_err("%s: invalid size requested: %d\n", __func__, nb);
+		err = -EINVAL;
+		goto out;
+	}
+	blen = ALIGN(nb, 4);
+	packet = kzalloc(sizeof(struct if_spi_packet) + blen, GFP_ATOMIC);
+	if (!packet) {
+		err = -ENOMEM;
+		goto out;
+	}
+	packet->blen = blen;
+	memcpy(packet->buffer, buf, nb);
+	memset(packet->buffer + nb, 0, blen - nb);
+
+	switch (type) {
+	case MVMS_CMD:
+		priv->dnld_sent = DNLD_CMD_SENT;
+		spin_lock_irqsave(&card->buffer_lock, flags);
+		list_add_tail(&packet->list, &card->cmd_packet_list);
+		spin_unlock_irqrestore(&card->buffer_lock, flags);
+		break;
+	case MVMS_DAT:
+		priv->dnld_sent = DNLD_DATA_SENT;
+		spin_lock_irqsave(&card->buffer_lock, flags);
+		list_add_tail(&packet->list, &card->data_packet_list);
+		spin_unlock_irqrestore(&card->buffer_lock, flags);
+		break;
+	default:
+		lbs_pr_err("can't transfer buffer of type %d", type);
+		err = -EINVAL;
+		break;
+	}
+
+	/* Wake up the spi thread */
+	up(&card->spi_ready);
+out:
+	lbs_deb_leave_args(LBS_DEB_SPI, "err=%d", err);
+	return err;
+}
+
+/*
+ * Host Interrupts
+ *
+ * Service incoming interrupts from the WLAN device. We can't sleep here, so
+ * don't try to talk on the SPI bus, just wake up the SPI thread.
+ */
+static irqreturn_t if_spi_host_interrupt(int irq, void *dev_id)
+{
+	struct if_spi_card *card = dev_id;
+
+	up(&card->spi_ready);
+	return IRQ_HANDLED;
+}
+
+/*
+ * SPI callbacks
+ */
+
+static int if_spi_calculate_fw_names(u16 card_id,
+			      char *helper_fw, char *main_fw)
+{
+	int i;
+	for (i = 0; i < ARRAY_SIZE(chip_id_to_device_name); ++i) {
+		if (card_id == chip_id_to_device_name[i].chip_id)
+			break;
+	}
+	if (i == ARRAY_SIZE(chip_id_to_device_name)) {
+		lbs_pr_err("Unsupported chip_id: 0x%02x\n", card_id);
+		return -EAFNOSUPPORT;
+	}
+	snprintf(helper_fw, FIRMWARE_NAME_MAX, "libertas/gspi%d_hlp.bin",
+		 chip_id_to_device_name[i].name);
+	snprintf(main_fw, FIRMWARE_NAME_MAX, "libertas/gspi%d.bin",
+		 chip_id_to_device_name[i].name);
+	return 0;
+}
+
+static int __devinit if_spi_probe(struct spi_device *spi)
+{
+	struct if_spi_card *card;
+	struct lbs_private *priv = NULL;
+	struct libertas_spi_platform_data *pdata = spi->dev.platform_data;
+	int err = 0;
+	u32 scratch;
+
+	lbs_deb_enter(LBS_DEB_SPI);
+
+	/* Allocate card structure to represent this specific device */
+	card = kzalloc(sizeof(struct if_spi_card), GFP_KERNEL);
+	if (!card) {
+		err = -ENOMEM;
+		goto out;
+	}
+	spi_set_drvdata(spi, card);
+	card->spi = spi;
+	card->gpio_cs = pdata->gpio_cs;
+	card->prev_xfer_time = jiffies;
+
+	sema_init(&card->spi_ready, 0);
+	sema_init(&card->spi_thread_terminated, 0);
+	INIT_LIST_HEAD(&card->cmd_packet_list);
+	INIT_LIST_HEAD(&card->data_packet_list);
+	spin_lock_init(&card->buffer_lock);
+
+	/* set up GPIO CS line. TODO: use  regular CS line */
+	err = gpio_request(card->gpio_cs, "if_spi_gpio_chip_select");
+	if (err)
+		goto free_card;
+	err = gpio_direction_output(card->gpio_cs, 1);
+	if (err)
+		goto free_gpio;
+
+	/* Initialize the SPI Interface Unit */
+	err = spu_init(card, pdata->use_dummy_writes);
+	if (err)
+		goto free_gpio;
+	err = spu_get_chip_revision(card, &card->card_id, &card->card_rev);
+	if (err)
+		goto free_gpio;
+
+	/* Firmware load */
+	err = spu_read_u32(card, IF_SPI_SCRATCH_4_REG, &scratch);
+	if (err)
+		goto free_gpio;
+	if (scratch == SUCCESSFUL_FW_DOWNLOAD_MAGIC)
+		lbs_deb_spi("Firmware is already loaded for "
+			    "Marvell WLAN 802.11 adapter\n");
+	else {
+		err = if_spi_calculate_fw_names(card->card_id,
+				card->helper_fw_name, card->main_fw_name);
+		if (err)
+			goto free_gpio;
+
+		lbs_deb_spi("Initializing FW for Marvell WLAN 802.11 adapter "
+				"(chip_id = 0x%04x, chip_rev = 0x%02x) "
+				"attached to SPI bus_num %d, chip_select %d. "
+				"spi->max_speed_hz=%d\n",
+				card->card_id, card->card_rev,
+				spi->master->bus_num, spi->chip_select,
+				spi->max_speed_hz);
+		err = if_spi_prog_helper_firmware(card);
+		if (err)
+			goto free_gpio;
+		err = if_spi_prog_main_firmware(card);
+		if (err)
+			goto free_gpio;
+		lbs_deb_spi("loaded FW for Marvell WLAN 802.11 adapter\n");
+	}
+
+	err = spu_set_interrupt_mode(card, 0, 1);
+	if (err)
+		goto free_gpio;
+
+	/* Register our card with libertas.
+	 * This will call alloc_etherdev */
+	priv = lbs_add_card(card, &spi->dev);
+	if (!priv) {
+		err = -ENOMEM;
+		goto free_gpio;
+	}
+	card->priv = priv;
+	priv->card = card;
+	priv->hw_host_to_card = if_spi_host_to_card;
+	priv->fw_ready = 1;
+	priv->ps_supported = 1;
+
+	/* Initialize interrupt handling stuff. */
+	card->run_thread = 1;
+	card->spi_thread = kthread_run(lbs_spi_thread, card, "lbs_spi_thread");
+	if (IS_ERR(card->spi_thread)) {
+		card->run_thread = 0;
+		err = PTR_ERR(card->spi_thread);
+		lbs_pr_err("error creating SPI thread: err=%d\n", err);
+		goto remove_card;
+	}
+	err = request_irq(spi->irq, if_spi_host_interrupt,
+			IRQF_TRIGGER_FALLING, "libertas_spi", card);
+	if (err) {
+		lbs_pr_err("can't get host irq line-- request_irq failed\n");
+		goto terminate_thread;
+	}
+
+	/* Start the card.
+	 * This will call register_netdev, and we'll start
+	 * getting interrupts... */
+	err = lbs_start_card(priv);
+	if (err)
+		goto release_irq;
+
+	lbs_deb_spi("Finished initializing WLAN module.\n");
+
+	/* successful exit */
+	goto out;
+
+release_irq:
+	free_irq(spi->irq, card);
+terminate_thread:
+	if_spi_terminate_spi_thread(card);
+remove_card:
+	lbs_remove_card(priv); /* will call free_netdev */
+free_gpio:
+	gpio_free(card->gpio_cs);
+free_card:
+	free_if_spi_card(card);
+out:
+	lbs_deb_leave_args(LBS_DEB_SPI, "err %d\n", err);
+	return err;
+}
+
+static int __devexit libertas_spi_remove(struct spi_device *spi)
+{
+	struct if_spi_card *card = spi_get_drvdata(spi);
+	struct lbs_private *priv = card->priv;
+
+	lbs_deb_spi("libertas_spi_remove\n");
+	lbs_deb_enter(LBS_DEB_SPI);
+	priv->surpriseremoved = 1;
+
+	lbs_stop_card(priv);
+	free_irq(spi->irq, card);
+	if_spi_terminate_spi_thread(card);
+	lbs_remove_card(priv); /* will call free_netdev */
+	gpio_free(card->gpio_cs);
+	free_if_spi_card(card);
+	lbs_deb_leave(LBS_DEB_SPI);
+	return 0;
+}
+
+static struct spi_driver libertas_spi_driver = {
+	.probe	= if_spi_probe,
+	.remove = __devexit_p(libertas_spi_remove),
+	.driver = {
+		.name	= "libertas_spi",
+		.bus	= &spi_bus_type,
+		.owner	= THIS_MODULE,
+	},
+};
+
+/*
+ * Module functions
+ */
+
+static int __init if_spi_init_module(void)
+{
+	int ret = 0;
+	lbs_deb_enter(LBS_DEB_SPI);
+	printk(KERN_INFO "libertas_spi: Libertas SPI driver\n");
+	ret = spi_register_driver(&libertas_spi_driver);
+	lbs_deb_leave(LBS_DEB_SPI);
+	return ret;
+}
+
+static void __exit if_spi_exit_module(void)
+{
+	lbs_deb_enter(LBS_DEB_SPI);
+	spi_unregister_driver(&libertas_spi_driver);
+	lbs_deb_leave(LBS_DEB_SPI);
+}
+
+module_init(if_spi_init_module);
+module_exit(if_spi_exit_module);
+
+MODULE_DESCRIPTION("Libertas SPI WLAN Driver");
+MODULE_AUTHOR("Andrey Yurovsky <andrey@cozybit.com>, "
+	      "Colin McCabe <colin@cozybit.com>");
+MODULE_LICENSE("GPL");