ieee802154: MRF24J40 driver

Driver for the Microchip MRF24J40 802.15.4 WPAN module.

Signed-off-by: Alan Ott <alan@signal11.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 779 insertions, 0 deletions

diff --git a/drivers/net/ieee802154/Kconfig b/drivers/net/ieee802154/Kconfig
index 1fc4eefc20e..08ae4655423 100644
--- a/drivers/net/ieee802154/Kconfig
+++ b/drivers/net/ieee802154/Kconfig
@@ -34,3 +34,14 @@ config IEEE802154_AT86RF230
         depends on IEEE802154_DRIVERS && MAC802154
         tristate "AT86RF230/231 transceiver driver"
         depends on SPI
+
+config IEEE802154_MRF24J40
+       tristate "Microchip MRF24J40 transceiver driver"
+       depends on IEEE802154_DRIVERS && MAC802154
+       depends on SPI
+       ---help---
+         Say Y here to enable the MRF24J20 SPI 802.15.4 wireless
+         controller.
+
+         This driver can also be built as a module. To do so, say M here.
+         the module will be called 'mrf24j40'.
diff --git a/drivers/net/ieee802154/Makefile b/drivers/net/ieee802154/Makefile
index 4f4371d3aa7..abb0c08decb 100644
--- a/drivers/net/ieee802154/Makefile
+++ b/drivers/net/ieee802154/Makefile
@@ -1,3 +1,4 @@
 obj-$(CONFIG_IEEE802154_FAKEHARD) += fakehard.o
 obj-$(CONFIG_IEEE802154_FAKELB) += fakelb.o
 obj-$(CONFIG_IEEE802154_AT86RF230) += at86rf230.o
+obj-$(CONFIG_IEEE802154_MRF24J40) += mrf24j40.o
diff --git a/drivers/net/ieee802154/mrf24j40.c b/drivers/net/ieee802154/mrf24j40.c
new file mode 100644
index 00000000000..0e53d4f431d
--- /dev/null
+++ b/drivers/net/ieee802154/mrf24j40.c
@@ -0,0 +1,767 @@
+/*
+ * Driver for Microchip MRF24J40 802.15.4 Wireless-PAN Networking controller
+ *
+ * Copyright (C) 2012 Alan Ott <alan@signal11.us>
+ *                    Signal 11 Software
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/spi/spi.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <net/wpan-phy.h>
+#include <net/mac802154.h>
+
+/* MRF24J40 Short Address Registers */
+#define REG_RXMCR    0x00  /* Receive MAC control */
+#define REG_PANIDL   0x01  /* PAN ID (low) */
+#define REG_PANIDH   0x02  /* PAN ID (high) */
+#define REG_SADRL    0x03  /* Short address (low) */
+#define REG_SADRH    0x04  /* Short address (high) */
+#define REG_EADR0    0x05  /* Long address (low) (high is EADR7) */
+#define REG_TXMCR    0x11  /* Transmit MAC control */
+#define REG_PACON0   0x16  /* Power Amplifier Control */
+#define REG_PACON1   0x17  /* Power Amplifier Control */
+#define REG_PACON2   0x18  /* Power Amplifier Control */
+#define REG_TXNCON   0x1B  /* Transmit Normal FIFO Control */
+#define REG_TXSTAT   0x24  /* TX MAC Status Register */
+#define REG_SOFTRST  0x2A  /* Soft Reset */
+#define REG_TXSTBL   0x2E  /* TX Stabilization */
+#define REG_INTSTAT  0x31  /* Interrupt Status */
+#define REG_INTCON   0x32  /* Interrupt Control */
+#define REG_RFCTL    0x36  /* RF Control Mode Register */
+#define REG_BBREG1   0x39  /* Baseband Registers */
+#define REG_BBREG2   0x3A  /* */
+#define REG_BBREG6   0x3E  /* */
+#define REG_CCAEDTH  0x3F  /* Energy Detection Threshold */
+
+/* MRF24J40 Long Address Registers */
+#define REG_RFCON0     0x200  /* RF Control Registers */
+#define REG_RFCON1     0x201
+#define REG_RFCON2     0x202
+#define REG_RFCON3     0x203
+#define REG_RFCON5     0x205
+#define REG_RFCON6     0x206
+#define REG_RFCON7     0x207
+#define REG_RFCON8     0x208
+#define REG_RSSI       0x210
+#define REG_SLPCON0    0x211  /* Sleep Clock Control Registers */
+#define REG_SLPCON1    0x220
+#define REG_WAKETIMEL  0x222  /* Wake-up Time Match Value Low */
+#define REG_WAKETIMEH  0x223  /* Wake-up Time Match Value High */
+#define REG_RX_FIFO    0x300  /* Receive FIFO */
+
+/* Device configuration: Only channels 11-26 on page 0 are supported. */
+#define MRF24J40_CHAN_MIN 11
+#define MRF24J40_CHAN_MAX 26
+#define CHANNEL_MASK (((u32)1 << (MRF24J40_CHAN_MAX + 1)) \
+		      - ((u32)1 << MRF24J40_CHAN_MIN))
+
+#define TX_FIFO_SIZE 128 /* From datasheet */
+#define RX_FIFO_SIZE 144 /* From datasheet */
+#define SET_CHANNEL_DELAY_US 192 /* From datasheet */
+
+/* Device Private Data */
+struct mrf24j40 {
+	struct spi_device *spi;
+	struct ieee802154_dev *dev;
+
+	struct mutex buffer_mutex; /* only used to protect buf */
+	struct completion tx_complete;
+	struct work_struct irqwork;
+	u8 *buf; /* 3 bytes. Used for SPI single-register transfers. */
+};
+
+/* Read/Write SPI Commands for Short and Long Address registers. */
+#define MRF24J40_READSHORT(reg) ((reg) << 1)
+#define MRF24J40_WRITESHORT(reg) ((reg) << 1 | 1)
+#define MRF24J40_READLONG(reg) (1 << 15 | (reg) << 5)
+#define MRF24J40_WRITELONG(reg) (1 << 15 | (reg) << 5 | 1 << 4)
+
+/* Maximum speed to run the device at. TODO: Get the real max value from
+ * someone at Microchip since it isn't in the datasheet. */
+#define MAX_SPI_SPEED_HZ 1000000
+
+#define printdev(X) (&X->spi->dev)
+
+static int write_short_reg(struct mrf24j40 *devrec, u8 reg, u8 value)
+{
+	int ret;
+	struct spi_message msg;
+	struct spi_transfer xfer = {
+		.len = 2,
+		.tx_buf = devrec->buf,
+		.rx_buf = devrec->buf,
+	};
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfer, &msg);
+
+	mutex_lock(&devrec->buffer_mutex);
+	devrec->buf[0] = MRF24J40_WRITESHORT(reg);
+	devrec->buf[1] = value;
+
+	ret = spi_sync(devrec->spi, &msg);
+	if (ret)
+		dev_err(printdev(devrec),
+			"SPI write Failed for short register 0x%hhx\n", reg);
+
+	mutex_unlock(&devrec->buffer_mutex);
+	return ret;
+}
+
+static int read_short_reg(struct mrf24j40 *devrec, u8 reg, u8 *val)
+{
+	int ret = -1;
+	struct spi_message msg;
+	struct spi_transfer xfer = {
+		.len = 2,
+		.tx_buf = devrec->buf,
+		.rx_buf = devrec->buf,
+	};
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfer, &msg);
+
+	mutex_lock(&devrec->buffer_mutex);
+	devrec->buf[0] = MRF24J40_READSHORT(reg);
+	devrec->buf[1] = 0;
+
+	ret = spi_sync(devrec->spi, &msg);
+	if (ret)
+		dev_err(printdev(devrec),
+			"SPI read Failed for short register 0x%hhx\n", reg);
+	else
+		*val = devrec->buf[1];
+
+	mutex_unlock(&devrec->buffer_mutex);
+	return ret;
+}
+
+static int read_long_reg(struct mrf24j40 *devrec, u16 reg, u8 *value)
+{
+	int ret;
+	u16 cmd;
+	struct spi_message msg;
+	struct spi_transfer xfer = {
+		.len = 3,
+		.tx_buf = devrec->buf,
+		.rx_buf = devrec->buf,
+	};
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfer, &msg);
+
+	cmd = MRF24J40_READLONG(reg);
+	mutex_lock(&devrec->buffer_mutex);
+	devrec->buf[0] = cmd >> 8 & 0xff;
+	devrec->buf[1] = cmd & 0xff;
+	devrec->buf[2] = 0;
+
+	ret = spi_sync(devrec->spi, &msg);
+	if (ret)
+		dev_err(printdev(devrec),
+			"SPI read Failed for long register 0x%hx\n", reg);
+	else
+		*value = devrec->buf[2];
+
+	mutex_unlock(&devrec->buffer_mutex);
+	return ret;
+}
+
+static int write_long_reg(struct mrf24j40 *devrec, u16 reg, u8 val)
+{
+	int ret;
+	u16 cmd;
+	struct spi_message msg;
+	struct spi_transfer xfer = {
+		.len = 3,
+		.tx_buf = devrec->buf,
+		.rx_buf = devrec->buf,
+	};
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfer, &msg);
+
+	cmd = MRF24J40_WRITELONG(reg);
+	mutex_lock(&devrec->buffer_mutex);
+	devrec->buf[0] = cmd >> 8 & 0xff;
+	devrec->buf[1] = cmd & 0xff;
+	devrec->buf[2] = val;
+
+	ret = spi_sync(devrec->spi, &msg);
+	if (ret)
+		dev_err(printdev(devrec),
+			"SPI write Failed for long register 0x%hx\n", reg);
+
+	mutex_unlock(&devrec->buffer_mutex);
+	return ret;
+}
+
+/* This function relies on an undocumented write method. Once a write command
+   and address is set, as many bytes of data as desired can be clocked into
+   the device. The datasheet only shows setting one byte at a time. */
+static int write_tx_buf(struct mrf24j40 *devrec, u16 reg,
+			const u8 *data, size_t length)
+{
+	int ret;
+	u16 cmd;
+	u8 lengths[2];
+	struct spi_message msg;
+	struct spi_transfer addr_xfer = {
+		.len = 2,
+		.tx_buf = devrec->buf,
+	};
+	struct spi_transfer lengths_xfer = {
+		.len = 2,
+		.tx_buf = &lengths, /* TODO: Is DMA really required for SPI? */
+	};
+	struct spi_transfer data_xfer = {
+		.len = length,
+		.tx_buf = data,
+	};
+
+	/* Range check the length. 2 bytes are used for the length fields.*/
+	if (length > TX_FIFO_SIZE-2) {
+		dev_err(printdev(devrec), "write_tx_buf() was passed too large a buffer. Performing short write.\n");
+		length = TX_FIFO_SIZE-2;
+	}
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&addr_xfer, &msg);
+	spi_message_add_tail(&lengths_xfer, &msg);
+	spi_message_add_tail(&data_xfer, &msg);
+
+	cmd = MRF24J40_WRITELONG(reg);
+	mutex_lock(&devrec->buffer_mutex);
+	devrec->buf[0] = cmd >> 8 & 0xff;
+	devrec->buf[1] = cmd & 0xff;
+	lengths[0] = 0x0; /* Header Length. Set to 0 for now. TODO */
+	lengths[1] = length; /* Total length */
+
+	ret = spi_sync(devrec->spi, &msg);
+	if (ret)
+		dev_err(printdev(devrec), "SPI write Failed for TX buf\n");
+
+	mutex_unlock(&devrec->buffer_mutex);
+	return ret;
+}
+
+static int mrf24j40_read_rx_buf(struct mrf24j40 *devrec,
+				u8 *data, u8 *len, u8 *lqi)
+{
+	u8 rx_len;
+	u8 addr[2];
+	u8 lqi_rssi[2];
+	u16 cmd;
+	int ret;
+	struct spi_message msg;
+	struct spi_transfer addr_xfer = {
+		.len = 2,
+		.tx_buf = &addr,
+	};
+	struct spi_transfer data_xfer = {
+		.len = 0x0, /* set below */
+		.rx_buf = data,
+	};
+	struct spi_transfer status_xfer = {
+		.len = 2,
+		.rx_buf = &lqi_rssi,
+	};
+
+	/* Get the length of the data in the RX FIFO. The length in this
+	 * register exclues the 1-byte length field at the beginning. */
+	ret = read_long_reg(devrec, REG_RX_FIFO, &rx_len);
+	if (ret)
+		goto out;
+
+	/* Range check the RX FIFO length, accounting for the one-byte
+	 * length field at the begining. */
+	if (rx_len > RX_FIFO_SIZE-1) {
+		dev_err(printdev(devrec), "Invalid length read from device. Performing short read.\n");
+		rx_len = RX_FIFO_SIZE-1;
+	}
+
+	if (rx_len > *len) {
+		/* Passed in buffer wasn't big enough. Should never happen. */
+		dev_err(printdev(devrec), "Buffer not big enough. Performing short read\n");
+		rx_len = *len;
+	}
+
+	/* Set up the commands to read the data. */
+	cmd = MRF24J40_READLONG(REG_RX_FIFO+1);
+	addr[0] = cmd >> 8 & 0xff;
+	addr[1] = cmd & 0xff;
+	data_xfer.len = rx_len;
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&addr_xfer, &msg);
+	spi_message_add_tail(&data_xfer, &msg);
+	spi_message_add_tail(&status_xfer, &msg);
+
+	ret = spi_sync(devrec->spi, &msg);
+	if (ret) {
+		dev_err(printdev(devrec), "SPI RX Buffer Read Failed.\n");
+		goto out;
+	}
+
+	*lqi = lqi_rssi[0];
+	*len = rx_len;
+
+#ifdef DEBUG
+	print_hex_dump(KERN_DEBUG, "mrf24j40 rx: ",
+		DUMP_PREFIX_OFFSET, 16, 1, data, *len, 0);
+	printk(KERN_DEBUG "mrf24j40 rx: lqi: %02hhx rssi: %02hhx\n",
+		lqi_rssi[0], lqi_rssi[1]);
+#endif
+
+out:
+	return ret;
+}
+
+static int mrf24j40_tx(struct ieee802154_dev *dev, struct sk_buff *skb)
+{
+	struct mrf24j40 *devrec = dev->priv;
+	u8 val;
+	int ret = 0;
+
+	dev_dbg(printdev(devrec), "tx packet of %d bytes\n", skb->len);
+
+	ret = write_tx_buf(devrec, 0x000, skb->data, skb->len);
+	if (ret)
+		goto err;
+
+	/* Set TXNTRIG bit of TXNCON to send packet */
+	ret = read_short_reg(devrec, REG_TXNCON, &val);
+	if (ret)
+		goto err;
+	val |= 0x1;
+	val &= ~0x4;
+	write_short_reg(devrec, REG_TXNCON, val);
+
+	INIT_COMPLETION(devrec->tx_complete);
+
+	/* Wait for the device to send the TX complete interrupt. */
+	ret = wait_for_completion_interruptible_timeout(
+						&devrec->tx_complete,
+						5 * HZ);
+	if (ret == -ERESTARTSYS)
+		goto err;
+	if (ret == 0) {
+		ret = -ETIMEDOUT;
+		goto err;
+	}
+
+	/* Check for send error from the device. */
+	ret = read_short_reg(devrec, REG_TXSTAT, &val);
+	if (ret)
+		goto err;
+	if (val & 0x1) {
+		dev_err(printdev(devrec), "Error Sending. Retry count exceeded\n");
+		ret = -ECOMM; /* TODO: Better error code ? */
+	} else
+		dev_dbg(printdev(devrec), "Packet Sent\n");
+
+err:
+
+	return ret;
+}
+
+static int mrf24j40_ed(struct ieee802154_dev *dev, u8 *level)
+{
+	/* TODO: */
+	printk(KERN_WARNING "mrf24j40: ed not implemented\n");
+	*level = 0;
+	return 0;
+}
+
+static int mrf24j40_start(struct ieee802154_dev *dev)
+{
+	struct mrf24j40 *devrec = dev->priv;
+	u8 val;
+	int ret;
+
+	dev_dbg(printdev(devrec), "start\n");
+
+	ret = read_short_reg(devrec, REG_INTCON, &val);
+	if (ret)
+		return ret;
+	val &= ~(0x1|0x8); /* Clear TXNIE and RXIE. Enable interrupts */
+	write_short_reg(devrec, REG_INTCON, val);
+
+	return 0;
+}
+
+static void mrf24j40_stop(struct ieee802154_dev *dev)
+{
+	struct mrf24j40 *devrec = dev->priv;
+	u8 val;
+	int ret;
+	dev_dbg(printdev(devrec), "stop\n");
+
+	ret = read_short_reg(devrec, REG_INTCON, &val);
+	if (ret)
+		return;
+	val |= 0x1|0x8; /* Set TXNIE and RXIE. Disable Interrupts */
+	write_short_reg(devrec, REG_INTCON, val);
+
+	return;
+}
+
+static int mrf24j40_set_channel(struct ieee802154_dev *dev,
+				int page, int channel)
+{
+	struct mrf24j40 *devrec = dev->priv;
+	u8 val;
+	int ret;
+
+	dev_dbg(printdev(devrec), "Set Channel %d\n", channel);
+
+	WARN_ON(page != 0);
+	WARN_ON(channel < MRF24J40_CHAN_MIN);
+	WARN_ON(channel > MRF24J40_CHAN_MAX);
+
+	/* Set Channel TODO */
+	val = (channel-11) << 4 | 0x03;
+	write_long_reg(devrec, REG_RFCON0, val);
+
+	/* RF Reset */
+	ret = read_short_reg(devrec, REG_RFCTL, &val);
+	if (ret)
+		return ret;
+	val |= 0x04;
+	write_short_reg(devrec, REG_RFCTL, val);
+	val &= ~0x04;
+	write_short_reg(devrec, REG_RFCTL, val);
+
+	udelay(SET_CHANNEL_DELAY_US); /* per datasheet */
+
+	return 0;
+}
+
+static int mrf24j40_filter(struct ieee802154_dev *dev,
+			   struct ieee802154_hw_addr_filt *filt,
+			   unsigned long changed)
+{
+	struct mrf24j40 *devrec = dev->priv;
+
+	dev_dbg(printdev(devrec), "filter\n");
+
+	if (changed & IEEE802515_AFILT_SADDR_CHANGED) {
+		/* Short Addr */
+		u8 addrh, addrl;
+		addrh = filt->short_addr >> 8 & 0xff;
+		addrl = filt->short_addr & 0xff;
+
+		write_short_reg(devrec, REG_SADRH, addrh);
+		write_short_reg(devrec, REG_SADRL, addrl);
+		dev_dbg(printdev(devrec),
+			"Set short addr to %04hx\n", filt->short_addr);
+	}
+
+	if (changed & IEEE802515_AFILT_IEEEADDR_CHANGED) {
+		/* Device Address */
+		int i;
+		for (i = 0; i < 8; i++)
+			write_short_reg(devrec, REG_EADR0+i,
+					filt->ieee_addr[i]);
+
+#ifdef DEBUG
+		printk(KERN_DEBUG "Set long addr to: ");
+		for (i = 0; i < 8; i++)
+			printk("%02hhx ", filt->ieee_addr[i]);
+		printk(KERN_DEBUG "\n");
+#endif
+	}
+
+	if (changed & IEEE802515_AFILT_PANID_CHANGED) {
+		/* PAN ID */
+		u8 panidl, panidh;
+		panidh = filt->pan_id >> 8 & 0xff;
+		panidl = filt->pan_id & 0xff;
+		write_short_reg(devrec, REG_PANIDH, panidh);
+		write_short_reg(devrec, REG_PANIDL, panidl);
+
+		dev_dbg(printdev(devrec), "Set PANID to %04hx\n", filt->pan_id);
+	}
+
+	if (changed & IEEE802515_AFILT_PANC_CHANGED) {
+		/* Pan Coordinator */
+		u8 val;
+		int ret;
+
+		ret = read_short_reg(devrec, REG_RXMCR, &val);
+		if (ret)
+			return ret;
+		if (filt->pan_coord)
+			val |= 0x8;
+		else
+			val &= ~0x8;
+		write_short_reg(devrec, REG_RXMCR, val);
+
+		/* REG_SLOTTED is maintained as default (unslotted/CSMA-CA).
+		 * REG_ORDER is maintained as default (no beacon/superframe).
+		 */
+
+		dev_dbg(printdev(devrec), "Set Pan Coord to %s\n",
+					filt->pan_coord ? "on" : "off");
+	}
+
+	return 0;
+}
+
+static int mrf24j40_handle_rx(struct mrf24j40 *devrec)
+{
+	u8 len = RX_FIFO_SIZE;
+	u8 lqi = 0;
+	u8 val;
+	int ret = 0;
+	struct sk_buff *skb;
+
+	/* Turn off reception of packets off the air. This prevents the
+	 * device from overwriting the buffer while we're reading it. */
+	ret = read_short_reg(devrec, REG_BBREG1, &val);
+	if (ret)
+		goto out;
+	val |= 4; /* SET RXDECINV */
+	write_short_reg(devrec, REG_BBREG1, val);
+
+	skb = alloc_skb(len, GFP_KERNEL);
+	if (!skb) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret = mrf24j40_read_rx_buf(devrec, skb_put(skb, len), &len, &lqi);
+	if (ret < 0) {
+		dev_err(printdev(devrec), "Failure reading RX FIFO\n");
+		kfree_skb(skb);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* Cut off the checksum */
+	skb_trim(skb, len-2);
+
+	/* TODO: Other drivers call ieee20154_rx_irqsafe() here (eg: cc2040,
+	 * also from a workqueue).  I think irqsafe is not necessary here.
+	 * Can someone confirm? */
+	ieee802154_rx_irqsafe(devrec->dev, skb, lqi);
+
+	dev_dbg(printdev(devrec), "RX Handled\n");
+
+out:
+	/* Turn back on reception of packets off the air. */
+	ret = read_short_reg(devrec, REG_BBREG1, &val);
+	if (ret)
+		return ret;
+	val &= ~0x4; /* Clear RXDECINV */
+	write_short_reg(devrec, REG_BBREG1, val);
+
+	return ret;
+}
+
+static struct ieee802154_ops mrf24j40_ops = {
+	.owner = THIS_MODULE,
+	.xmit = mrf24j40_tx,
+	.ed = mrf24j40_ed,
+	.start = mrf24j40_start,
+	.stop = mrf24j40_stop,
+	.set_channel = mrf24j40_set_channel,
+	.set_hw_addr_filt = mrf24j40_filter,
+};
+
+static irqreturn_t mrf24j40_isr(int irq, void *data)
+{
+	struct mrf24j40 *devrec = data;
+
+	disable_irq_nosync(irq);
+
+	schedule_work(&devrec->irqwork);
+
+	return IRQ_HANDLED;
+}
+
+static void mrf24j40_isrwork(struct work_struct *work)
+{
+	struct mrf24j40 *devrec = container_of(work, struct mrf24j40, irqwork);
+	u8 intstat;
+	int ret;
+
+	/* Read the interrupt status */
+	ret = read_short_reg(devrec, REG_INTSTAT, &intstat);
+	if (ret)
+		goto out;
+
+	/* Check for TX complete */
+	if (intstat & 0x1)
+		complete(&devrec->tx_complete);
+
+	/* Check for Rx */
+	if (intstat & 0x8)
+		mrf24j40_handle_rx(devrec);
+
+out:
+	enable_irq(devrec->spi->irq);
+}
+
+static int __devinit mrf24j40_probe(struct spi_device *spi)
+{
+	int ret = -ENOMEM;
+	u8 val;
+	struct mrf24j40 *devrec;
+
+	printk(KERN_INFO "mrf24j40: probe(). IRQ: %d\n", spi->irq);
+
+	devrec = kzalloc(sizeof(struct mrf24j40), GFP_KERNEL);
+	if (!devrec)
+		goto err_devrec;
+	devrec->buf = kzalloc(3, GFP_KERNEL);
+	if (!devrec->buf)
+		goto err_buf;
+
+	spi->mode = SPI_MODE_0; /* TODO: Is this appropriate for right here? */
+	if (spi->max_speed_hz > MAX_SPI_SPEED_HZ)
+		spi->max_speed_hz = MAX_SPI_SPEED_HZ;
+
+	mutex_init(&devrec->buffer_mutex);
+	init_completion(&devrec->tx_complete);
+	INIT_WORK(&devrec->irqwork, mrf24j40_isrwork);
+	devrec->spi = spi;
+	dev_set_drvdata(&spi->dev, devrec);
+
+	/* Register with the 802154 subsystem */
+
+	devrec->dev = ieee802154_alloc_device(0, &mrf24j40_ops);
+	if (!devrec->dev)
+		goto err_alloc_dev;
+
+	devrec->dev->priv = devrec;
+	devrec->dev->parent = &devrec->spi->dev;
+	devrec->dev->phy->channels_supported[0] = CHANNEL_MASK;
+	devrec->dev->flags = IEEE802154_HW_OMIT_CKSUM|IEEE802154_HW_AACK;
+
+	dev_dbg(printdev(devrec), "registered mrf24j40\n");
+	ret = ieee802154_register_device(devrec->dev);
+	if (ret)
+		goto err_register_device;
+
+	/* Initialize the device.
+		From datasheet section 3.2: Initialization. */
+	write_short_reg(devrec, REG_SOFTRST, 0x07);
+	write_short_reg(devrec, REG_PACON2, 0x98);
+	write_short_reg(devrec, REG_TXSTBL, 0x95);
+	write_long_reg(devrec, REG_RFCON0, 0x03);
+	write_long_reg(devrec, REG_RFCON1, 0x01);
+	write_long_reg(devrec, REG_RFCON2, 0x80);
+	write_long_reg(devrec, REG_RFCON6, 0x90);
+	write_long_reg(devrec, REG_RFCON7, 0x80);
+	write_long_reg(devrec, REG_RFCON8, 0x10);
+	write_long_reg(devrec, REG_SLPCON1, 0x21);
+	write_short_reg(devrec, REG_BBREG2, 0x80);
+	write_short_reg(devrec, REG_CCAEDTH, 0x60);
+	write_short_reg(devrec, REG_BBREG6, 0x40);
+	write_short_reg(devrec, REG_RFCTL, 0x04);
+	write_short_reg(devrec, REG_RFCTL, 0x0);
+	udelay(192);
+
+	/* Set RX Mode. RXMCR<1:0>: 0x0 normal, 0x1 promisc, 0x2 error */
+	ret = read_short_reg(devrec, REG_RXMCR, &val);
+	if (ret)
+		goto err_read_reg;
+	val &= ~0x3; /* Clear RX mode (normal) */
+	write_short_reg(devrec, REG_RXMCR, val);
+
+	ret = request_irq(spi->irq,
+			  mrf24j40_isr,
+			  IRQF_TRIGGER_FALLING,
+			  dev_name(&spi->dev),
+			  devrec);
+
+	if (ret) {
+		dev_err(printdev(devrec), "Unable to get IRQ");
+		goto err_irq;
+	}
+
+	return 0;
+
+err_irq:
+err_read_reg:
+	ieee802154_unregister_device(devrec->dev);
+err_register_device:
+	ieee802154_free_device(devrec->dev);
+err_alloc_dev:
+	kfree(devrec->buf);
+err_buf:
+	kfree(devrec);
+err_devrec:
+	return ret;
+}
+
+static int __devexit mrf24j40_remove(struct spi_device *spi)
+{
+	struct mrf24j40 *devrec = dev_get_drvdata(&spi->dev);
+
+	dev_dbg(printdev(devrec), "remove\n");
+
+	free_irq(spi->irq, devrec);
+	flush_work_sync(&devrec->irqwork); /* TODO: Is this the right call? */
+	ieee802154_unregister_device(devrec->dev);
+	ieee802154_free_device(devrec->dev);
+	/* TODO: Will ieee802154_free_device() wait until ->xmit() is
+	 * complete? */
+
+	/* Clean up the SPI stuff. */
+	dev_set_drvdata(&spi->dev, NULL);
+	kfree(devrec->buf);
+	kfree(devrec);
+	return 0;
+}
+
+static const struct spi_device_id mrf24j40_ids[] = {
+	{ "mrf24j40", 0 },
+	{ "mrf24j40ma", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(spi, mrf24j40_ids);
+
+static struct spi_driver mrf24j40_driver = {
+	.driver = {
+		.name = "mrf24j40",
+		.bus = &spi_bus_type,
+		.owner = THIS_MODULE,
+	},
+	.id_table = mrf24j40_ids,
+	.probe = mrf24j40_probe,
+	.remove = __devexit_p(mrf24j40_remove),
+};
+
+static int __init mrf24j40_init(void)
+{
+	return spi_register_driver(&mrf24j40_driver);
+}
+
+static void __exit mrf24j40_exit(void)
+{
+	spi_unregister_driver(&mrf24j40_driver);
+}
+
+module_init(mrf24j40_init);
+module_exit(mrf24j40_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Alan Ott");
+MODULE_DESCRIPTION("MRF24J40 SPI 802.15.4 Controller Driver");