can: Driver for the Microchip MCP251x SPI CAN controllers

Signed-off-by: Christian Pellegrin <[e-mail]>
Signed-off-by: Wolfgang Grandegger <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/can/Kconfig

···
 	  Driver for TI HECC (High End CAN Controller) module found on many
 	  TI devices. The device specifications are available from www.ti.com
 
+config CAN_MCP251X
+	tristate "Microchip MCP251x SPI CAN controllers"
+	depends on CAN_DEV && SPI
+	---help---
+	  Driver for the Microchip MCP251x SPI CAN controllers.
+
 config CAN_DEBUG_DEVICES
 	bool "CAN devices debugging messages"
 	depends on CAN

drivers/net/can/Makefile

···
 obj-$(CONFIG_CAN_SJA1000)	+= sja1000/
 obj-$(CONFIG_CAN_AT91)		+= at91_can.o
 obj-$(CONFIG_CAN_TI_HECC)	+= ti_hecc.o
+obj-$(CONFIG_CAN_MCP251X)	+= mcp251x.o
 
 ccflags-$(CONFIG_CAN_DEBUG_DEVICES) := -DDEBUG

drivers/net/can/mcp251x.c

···
+/*
+ * CAN bus driver for Microchip 251x CAN Controller with SPI Interface
+ *
+ * MCP2510 support and bug fixes by Christian Pellegrin
+ * <[e-mail]>
+ *
+ * Copyright 2009 Christian Pellegrin EVOL S.r.l.
+ *
+ * Copyright 2007 Raymarine UK, Ltd. All Rights Reserved.
+ * Written under contract by:
+ *   Chris Elston, Katalix Systems, Ltd.
+ *
+ * Based on Microchip MCP251x CAN controller driver written by
+ * David Vrabel, Copyright 2006 Arcom Control Systems Ltd.
+ *
+ * Based on CAN bus driver for the CCAN controller written by
+ * - Sascha Hauer, Marc Kleine-Budde, Pengutronix
+ * - Simon Kallweit, intefo AG
+ * Copyright 2007
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the version 2 of the GNU General Public License
+ * as published by the Free Software Foundation
+ *
+ * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *
+ *
+ * Your platform definition file should specify something like:
+ *
+ * static struct mcp251x_platform_data mcp251x_info = {
+ *         .oscillator_frequency = 8000000,
+ *         .board_specific_setup = &mcp251x_setup,
+ *         .model = CAN_MCP251X_MCP2510,
+ *         .power_enable = mcp251x_power_enable,
+ *         .transceiver_enable = NULL,
+ * };
+ *
+ * static struct spi_board_info spi_board_info[] = {
+ *         {
+ *                 .modalias = "mcp251x",
+ *                 .platform_data = &mcp251x_info,
+ *                 .irq = IRQ_EINT13,
+ *                 .max_speed_hz = 2*1000*1000,
+ *                 .chip_select = 2,
+ *         },
+ * };
+ *
+ * Please see mcp251x.h for a description of the fields in
+ * struct mcp251x_platform_data.
+ *
+ */
+
+#include <linux/can.h>
+#include <linux/can/core.h>
+#include <linux/can/dev.h>
+#include <linux/can/platform/mcp251x.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/freezer.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/platform_device.h>
+#include <linux/spi/spi.h>
+#include <linux/uaccess.h>
+
+/* SPI interface instruction set */
+#define INSTRUCTION_WRITE	0x02
+#define INSTRUCTION_READ	0x03
+#define INSTRUCTION_BIT_MODIFY	0x05
+#define INSTRUCTION_LOAD_TXB(n)	(0x40 + 2 * (n))
+#define INSTRUCTION_READ_RXB(n)	(((n) == 0) ? 0x90 : 0x94)
+#define INSTRUCTION_RESET	0xC0
+
+/* MPC251x registers */
+#define CANSTAT	      0x0e
+#define CANCTRL	      0x0f
+#  define CANCTRL_REQOP_MASK	    0xe0
+#  define CANCTRL_REQOP_CONF	    0x80
+#  define CANCTRL_REQOP_LISTEN_ONLY 0x60
+#  define CANCTRL_REQOP_LOOPBACK    0x40
+#  define CANCTRL_REQOP_SLEEP	    0x20
+#  define CANCTRL_REQOP_NORMAL	    0x00
+#  define CANCTRL_OSM		    0x08
+#  define CANCTRL_ABAT		    0x10
+#define TEC	      0x1c
+#define REC	      0x1d
+#define CNF1	      0x2a
+#  define CNF1_SJW_SHIFT   6
+#define CNF2	      0x29
+#  define CNF2_BTLMODE	   0x80
+#  define CNF2_SAM         0x40
+#  define CNF2_PS1_SHIFT   3
+#define CNF3	      0x28
+#  define CNF3_SOF	   0x08
+#  define CNF3_WAKFIL	   0x04
+#  define CNF3_PHSEG2_MASK 0x07
+#define CANINTE	      0x2b
+#  define CANINTE_MERRE 0x80
+#  define CANINTE_WAKIE 0x40
+#  define CANINTE_ERRIE 0x20
+#  define CANINTE_TX2IE 0x10
+#  define CANINTE_TX1IE 0x08
+#  define CANINTE_TX0IE 0x04
+#  define CANINTE_RX1IE 0x02
+#  define CANINTE_RX0IE 0x01
+#define CANINTF	      0x2c
+#  define CANINTF_MERRF 0x80
+#  define CANINTF_WAKIF 0x40
+#  define CANINTF_ERRIF 0x20
+#  define CANINTF_TX2IF 0x10
+#  define CANINTF_TX1IF 0x08
+#  define CANINTF_TX0IF 0x04
+#  define CANINTF_RX1IF 0x02
+#  define CANINTF_RX0IF 0x01
+#define EFLG	      0x2d
+#  define EFLG_EWARN	0x01
+#  define EFLG_RXWAR	0x02
+#  define EFLG_TXWAR	0x04
+#  define EFLG_RXEP	0x08
+#  define EFLG_TXEP	0x10
+#  define EFLG_TXBO	0x20
+#  define EFLG_RX0OVR	0x40
+#  define EFLG_RX1OVR	0x80
+#define TXBCTRL(n)  (((n) * 0x10) + 0x30 + TXBCTRL_OFF)
+#  define TXBCTRL_ABTF	0x40
+#  define TXBCTRL_MLOA	0x20
+#  define TXBCTRL_TXERR 0x10
+#  define TXBCTRL_TXREQ 0x08
+#define TXBSIDH(n)  (((n) * 0x10) + 0x30 + TXBSIDH_OFF)
+#  define SIDH_SHIFT    3
+#define TXBSIDL(n)  (((n) * 0x10) + 0x30 + TXBSIDL_OFF)
+#  define SIDL_SID_MASK    7
+#  define SIDL_SID_SHIFT   5
+#  define SIDL_EXIDE_SHIFT 3
+#  define SIDL_EID_SHIFT   16
+#  define SIDL_EID_MASK    3
+#define TXBEID8(n)  (((n) * 0x10) + 0x30 + TXBEID8_OFF)
+#define TXBEID0(n)  (((n) * 0x10) + 0x30 + TXBEID0_OFF)
+#define TXBDLC(n)   (((n) * 0x10) + 0x30 + TXBDLC_OFF)
+#  define DLC_RTR_SHIFT    6
+#define TXBCTRL_OFF 0
+#define TXBSIDH_OFF 1
+#define TXBSIDL_OFF 2
+#define TXBEID8_OFF 3
+#define TXBEID0_OFF 4
+#define TXBDLC_OFF  5
+#define TXBDAT_OFF  6
+#define RXBCTRL(n)  (((n) * 0x10) + 0x60 + RXBCTRL_OFF)
+#  define RXBCTRL_BUKT	0x04
+#  define RXBCTRL_RXM0	0x20
+#  define RXBCTRL_RXM1	0x40
+#define RXBSIDH(n)  (((n) * 0x10) + 0x60 + RXBSIDH_OFF)
+#  define RXBSIDH_SHIFT 3
+#define RXBSIDL(n)  (((n) * 0x10) + 0x60 + RXBSIDL_OFF)
+#  define RXBSIDL_IDE   0x08
+#  define RXBSIDL_EID   3
+#  define RXBSIDL_SHIFT 5
+#define RXBEID8(n)  (((n) * 0x10) + 0x60 + RXBEID8_OFF)
+#define RXBEID0(n)  (((n) * 0x10) + 0x60 + RXBEID0_OFF)
+#define RXBDLC(n)   (((n) * 0x10) + 0x60 + RXBDLC_OFF)
+#  define RXBDLC_LEN_MASK  0x0f
+#  define RXBDLC_RTR       0x40
+#define RXBCTRL_OFF 0
+#define RXBSIDH_OFF 1
+#define RXBSIDL_OFF 2
+#define RXBEID8_OFF 3
+#define RXBEID0_OFF 4
+#define RXBDLC_OFF  5
+#define RXBDAT_OFF  6
+
+#define GET_BYTE(val, byte)			\
+	(((val) >> ((byte) * 8)) & 0xff)
+#define SET_BYTE(val, byte)			\
+	(((val) & 0xff) << ((byte) * 8))
+
+/*
+ * Buffer size required for the largest SPI transfer (i.e., reading a
+ * frame)
+ */
+#define CAN_FRAME_MAX_DATA_LEN	8
+#define SPI_TRANSFER_BUF_LEN	(6 + CAN_FRAME_MAX_DATA_LEN)
+#define CAN_FRAME_MAX_BITS	128
+
+#define TX_ECHO_SKB_MAX	1
+
+#define DEVICE_NAME "mcp251x"
+
+static int mcp251x_enable_dma; /* Enable SPI DMA. Default: 0 (Off) */
+module_param(mcp251x_enable_dma, int, S_IRUGO);
+MODULE_PARM_DESC(mcp251x_enable_dma, "Enable SPI DMA. Default: 0 (Off)");
+
+static struct can_bittiming_const mcp251x_bittiming_const = {
+	.name = DEVICE_NAME,
+	.tseg1_min = 3,
+	.tseg1_max = 16,
+	.tseg2_min = 2,
+	.tseg2_max = 8,
+	.sjw_max = 4,
+	.brp_min = 1,
+	.brp_max = 64,
+	.brp_inc = 1,
+};
+
+struct mcp251x_priv {
+	struct can_priv	   can;
+	struct net_device *net;
+	struct spi_device *spi;
+
+	struct mutex spi_lock; /* SPI buffer lock */
+	u8 *spi_tx_buf;
+	u8 *spi_rx_buf;
+	dma_addr_t spi_tx_dma;
+	dma_addr_t spi_rx_dma;
+
+	struct sk_buff *tx_skb;
+	int tx_len;
+	struct workqueue_struct *wq;
+	struct work_struct tx_work;
+	struct work_struct irq_work;
+	struct completion awake;
+	int wake;
+	int force_quit;
+	int after_suspend;
+#define AFTER_SUSPEND_UP 1
+#define AFTER_SUSPEND_DOWN 2
+#define AFTER_SUSPEND_POWER 4
+#define AFTER_SUSPEND_RESTART 8
+	int restart_tx;
+};
+
+static void mcp251x_clean(struct net_device *net)
+{
+	struct mcp251x_priv *priv = netdev_priv(net);
+
+	net->stats.tx_errors++;
+	if (priv->tx_skb)
+		dev_kfree_skb(priv->tx_skb);
+	if (priv->tx_len)
+		can_free_echo_skb(priv->net, 0);
+	priv->tx_skb = NULL;
+	priv->tx_len = 0;
+}
+
+/*
+ * Note about handling of error return of mcp251x_spi_trans: accessing
+ * registers via SPI is not really different conceptually than using
+ * normal I/O assembler instructions, although it's much more
+ * complicated from a practical POV. So it's not advisable to always
+ * check the return value of this function. Imagine that every
+ * read{b,l}, write{b,l} and friends would be bracketed in "if ( < 0)
+ * error();", it would be a great mess (well there are some situation
+ * when exception handling C++ like could be useful after all). So we
+ * just check that transfers are OK at the beginning of our
+ * conversation with the chip and to avoid doing really nasty things
+ * (like injecting bogus packets in the network stack).
+ */
+static int mcp251x_spi_trans(struct spi_device *spi, int len)
+{
+	struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
+	struct spi_transfer t = {
+		.tx_buf = priv->spi_tx_buf,
+		.rx_buf = priv->spi_rx_buf,
+		.len = len,
+		.cs_change = 0,
+	};
+	struct spi_message m;
+	int ret;
+
+	spi_message_init(&m);
+
+	if (mcp251x_enable_dma) {
+		t.tx_dma = priv->spi_tx_dma;
+		t.rx_dma = priv->spi_rx_dma;
+		m.is_dma_mapped = 1;
+	}
+
+	spi_message_add_tail(&t, &m);
+
+	ret = spi_sync(spi, &m);
+	if (ret)
+		dev_err(&spi->dev, "spi transfer failed: ret = %d\n", ret);
+	return ret;
+}
+
+static u8 mcp251x_read_reg(struct spi_device *spi, uint8_t reg)
+{
+	struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
+	u8 val = 0;
+
+	mutex_lock(&priv->spi_lock);
+
+	priv->spi_tx_buf[0] = INSTRUCTION_READ;
+	priv->spi_tx_buf[1] = reg;
+
+	mcp251x_spi_trans(spi, 3);
+	val = priv->spi_rx_buf[2];
+
+	mutex_unlock(&priv->spi_lock);
+
+	return val;
+}
+
+static void mcp251x_write_reg(struct spi_device *spi, u8 reg, uint8_t val)
+{
+	struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
+
+	mutex_lock(&priv->spi_lock);
+
+	priv->spi_tx_buf[0] = INSTRUCTION_WRITE;
+	priv->spi_tx_buf[1] = reg;
+	priv->spi_tx_buf[2] = val;
+
+	mcp251x_spi_trans(spi, 3);
+
+	mutex_unlock(&priv->spi_lock);
+}
+
+static void mcp251x_write_bits(struct spi_device *spi, u8 reg,
+			       u8 mask, uint8_t val)
+{
+	struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
+
+	mutex_lock(&priv->spi_lock);
+
+	priv->spi_tx_buf[0] = INSTRUCTION_BIT_MODIFY;
+	priv->spi_tx_buf[1] = reg;
+	priv->spi_tx_buf[2] = mask;
+	priv->spi_tx_buf[3] = val;
+
+	mcp251x_spi_trans(spi, 4);
+
+	mutex_unlock(&priv->spi_lock);
+}
+
+static void mcp251x_hw_tx_frame(struct spi_device *spi, u8 *buf,
+				int len, int tx_buf_idx)
+{
+	struct mcp251x_platform_data *pdata = spi->dev.platform_data;
+	struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
+
+	if (pdata->model == CAN_MCP251X_MCP2510) {
+		int i;
+
+		for (i = 1; i < TXBDAT_OFF + len; i++)
+			mcp251x_write_reg(spi, TXBCTRL(tx_buf_idx) + i,
+					  buf[i]);
+	} else {
+		mutex_lock(&priv->spi_lock);
+		memcpy(priv->spi_tx_buf, buf, TXBDAT_OFF + len);
+		mcp251x_spi_trans(spi, TXBDAT_OFF + len);
+		mutex_unlock(&priv->spi_lock);
+	}
+}
+
+static void mcp251x_hw_tx(struct spi_device *spi, struct can_frame *frame,
+			  int tx_buf_idx)
+{
+	u32 sid, eid, exide, rtr;
+	u8 buf[SPI_TRANSFER_BUF_LEN];
+
+	exide = (frame->can_id & CAN_EFF_FLAG) ? 1 : 0; /* Extended ID Enable */
+	if (exide)
+		sid = (frame->can_id & CAN_EFF_MASK) >> 18;
+	else
+		sid = frame->can_id & CAN_SFF_MASK; /* Standard ID */
+	eid = frame->can_id & CAN_EFF_MASK; /* Extended ID */
+	rtr = (frame->can_id & CAN_RTR_FLAG) ? 1 : 0; /* Remote transmission */
+
+	buf[TXBCTRL_OFF] = INSTRUCTION_LOAD_TXB(tx_buf_idx);
+	buf[TXBSIDH_OFF] = sid >> SIDH_SHIFT;
+	buf[TXBSIDL_OFF] = ((sid & SIDL_SID_MASK) << SIDL_SID_SHIFT) |
+		(exide << SIDL_EXIDE_SHIFT) |
+		((eid >> SIDL_EID_SHIFT) & SIDL_EID_MASK);
+	buf[TXBEID8_OFF] = GET_BYTE(eid, 1);
+	buf[TXBEID0_OFF] = GET_BYTE(eid, 0);
+	buf[TXBDLC_OFF] = (rtr << DLC_RTR_SHIFT) | frame->can_dlc;
+	memcpy(buf + TXBDAT_OFF, frame->data, frame->can_dlc);
+	mcp251x_hw_tx_frame(spi, buf, frame->can_dlc, tx_buf_idx);
+	mcp251x_write_reg(spi, TXBCTRL(tx_buf_idx), TXBCTRL_TXREQ);
+}
+
+static void mcp251x_hw_rx_frame(struct spi_device *spi, u8 *buf,
+				int buf_idx)
+{
+	struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
+	struct mcp251x_platform_data *pdata = spi->dev.platform_data;
+
+	if (pdata->model == CAN_MCP251X_MCP2510) {
+		int i, len;
+
+		for (i = 1; i < RXBDAT_OFF; i++)
+			buf[i] = mcp251x_read_reg(spi, RXBCTRL(buf_idx) + i);
+		len = buf[RXBDLC_OFF] & RXBDLC_LEN_MASK;
+		if (len > 8)
+			len = 8;
+		for (; i < (RXBDAT_OFF + len); i++)
+			buf[i] = mcp251x_read_reg(spi, RXBCTRL(buf_idx) + i);
+	} else {
+		mutex_lock(&priv->spi_lock);
+
+		priv->spi_tx_buf[RXBCTRL_OFF] = INSTRUCTION_READ_RXB(buf_idx);
+		mcp251x_spi_trans(spi, SPI_TRANSFER_BUF_LEN);
+		memcpy(buf, priv->spi_rx_buf, SPI_TRANSFER_BUF_LEN);
+
+		mutex_unlock(&priv->spi_lock);
+	}
+}
+
+static void mcp251x_hw_rx(struct spi_device *spi, int buf_idx)
+{
+	struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
+	struct sk_buff *skb;
+	struct can_frame *frame;
+	u8 buf[SPI_TRANSFER_BUF_LEN];
+
+	skb = alloc_can_skb(priv->net, &frame);
+	if (!skb) {
+		dev_err(&spi->dev, "cannot allocate RX skb\n");
+		priv->net->stats.rx_dropped++;
+		return;
+	}
+
+	mcp251x_hw_rx_frame(spi, buf, buf_idx);
+	if (buf[RXBSIDL_OFF] & RXBSIDL_IDE) {
+		/* Extended ID format */
+		frame->can_id = CAN_EFF_FLAG;
+		frame->can_id |=
+			/* Extended ID part */
+			SET_BYTE(buf[RXBSIDL_OFF] & RXBSIDL_EID, 2) |
+			SET_BYTE(buf[RXBEID8_OFF], 1) |
+			SET_BYTE(buf[RXBEID0_OFF], 0) |
+			/* Standard ID part */
+			(((buf[RXBSIDH_OFF] << RXBSIDH_SHIFT) |
+			  (buf[RXBSIDL_OFF] >> RXBSIDL_SHIFT)) << 18);
+		/* Remote transmission request */
+		if (buf[RXBDLC_OFF] & RXBDLC_RTR)
+			frame->can_id |= CAN_RTR_FLAG;
+	} else {
+		/* Standard ID format */
+		frame->can_id =
+			(buf[RXBSIDH_OFF] << RXBSIDH_SHIFT) |
+			(buf[RXBSIDL_OFF] >> RXBSIDL_SHIFT);
+	}
+	/* Data length */
+	frame->can_dlc = buf[RXBDLC_OFF] & RXBDLC_LEN_MASK;
+	if (frame->can_dlc > 8) {
+		dev_warn(&spi->dev, "invalid frame recevied\n");
+		priv->net->stats.rx_errors++;
+		dev_kfree_skb(skb);
+		return;
+	}
+	memcpy(frame->data, buf + RXBDAT_OFF, frame->can_dlc);
+
+	priv->net->stats.rx_packets++;
+	priv->net->stats.rx_bytes += frame->can_dlc;
+	netif_rx(skb);
+}
+
+static void mcp251x_hw_sleep(struct spi_device *spi)
+{
+	mcp251x_write_reg(spi, CANCTRL, CANCTRL_REQOP_SLEEP);
+}
+
+static void mcp251x_hw_wakeup(struct spi_device *spi)
+{
+	struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
+
+	priv->wake = 1;
+
+	/* Can only wake up by generating a wake-up interrupt. */
+	mcp251x_write_bits(spi, CANINTE, CANINTE_WAKIE, CANINTE_WAKIE);
+	mcp251x_write_bits(spi, CANINTF, CANINTF_WAKIF, CANINTF_WAKIF);
+
+	/* Wait until the device is awake */
+	if (!wait_for_completion_timeout(&priv->awake, HZ))
+		dev_err(&spi->dev, "MCP251x didn't wake-up\n");
+}
+
+static netdev_tx_t mcp251x_hard_start_xmit(struct sk_buff *skb,
+					   struct net_device *net)
+{
+	struct mcp251x_priv *priv = netdev_priv(net);
+	struct spi_device *spi = priv->spi;
+
+	if (priv->tx_skb || priv->tx_len) {
+		dev_warn(&spi->dev, "hard_xmit called while tx busy\n");
+		netif_stop_queue(net);
+		return NETDEV_TX_BUSY;
+	}
+
+	if (skb->len != sizeof(struct can_frame)) {
+		dev_err(&spi->dev, "dropping packet - bad length\n");
+		dev_kfree_skb(skb);
+		net->stats.tx_dropped++;
+		return NETDEV_TX_OK;
+	}
+
+	netif_stop_queue(net);
+	priv->tx_skb = skb;
+	net->trans_start = jiffies;
+	queue_work(priv->wq, &priv->tx_work);
+
+	return NETDEV_TX_OK;
+}
+
+static int mcp251x_do_set_mode(struct net_device *net, enum can_mode mode)
+{
+	struct mcp251x_priv *priv = netdev_priv(net);
+
+	switch (mode) {
+	case CAN_MODE_START:
+		/* We have to delay work since SPI I/O may sleep */
+		priv->can.state = CAN_STATE_ERROR_ACTIVE;
+		priv->restart_tx = 1;
+		if (priv->can.restart_ms == 0)
+			priv->after_suspend = AFTER_SUSPEND_RESTART;
+		queue_work(priv->wq, &priv->irq_work);
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static void mcp251x_set_normal_mode(struct spi_device *spi)
+{
+	struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
+	unsigned long timeout;
+
+	/* Enable interrupts */
+	mcp251x_write_reg(spi, CANINTE,
+			  CANINTE_ERRIE | CANINTE_TX2IE | CANINTE_TX1IE |
+			  CANINTE_TX0IE | CANINTE_RX1IE | CANINTE_RX0IE |
+			  CANINTF_MERRF);
+
+	if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK) {
+		/* Put device into loopback mode */
+		mcp251x_write_reg(spi, CANCTRL, CANCTRL_REQOP_LOOPBACK);
+	} else {
+		/* Put device into normal mode */
+		mcp251x_write_reg(spi, CANCTRL, CANCTRL_REQOP_NORMAL);
+
+		/* Wait for the device to enter normal mode */
+		timeout = jiffies + HZ;
+		while (mcp251x_read_reg(spi, CANSTAT) & CANCTRL_REQOP_MASK) {
+			schedule();
+			if (time_after(jiffies, timeout)) {
+				dev_err(&spi->dev, "MCP251x didn't"
+					" enter in normal mode\n");
+				return;
+			}
+		}
+	}
+	priv->can.state = CAN_STATE_ERROR_ACTIVE;
+}
+
+static int mcp251x_do_set_bittiming(struct net_device *net)
+{
+	struct mcp251x_priv *priv = netdev_priv(net);
+	struct can_bittiming *bt = &priv->can.bittiming;
+	struct spi_device *spi = priv->spi;
+
+	mcp251x_write_reg(spi, CNF1, ((bt->sjw - 1) << CNF1_SJW_SHIFT) |
+			  (bt->brp - 1));
+	mcp251x_write_reg(spi, CNF2, CNF2_BTLMODE |
+			  (priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES ?
+			   CNF2_SAM : 0) |
+			  ((bt->phase_seg1 - 1) << CNF2_PS1_SHIFT) |
+			  (bt->prop_seg - 1));
+	mcp251x_write_bits(spi, CNF3, CNF3_PHSEG2_MASK,
+			   (bt->phase_seg2 - 1));
+	dev_info(&spi->dev, "CNF: 0x%02x 0x%02x 0x%02x\n",
+		 mcp251x_read_reg(spi, CNF1),
+		 mcp251x_read_reg(spi, CNF2),
+		 mcp251x_read_reg(spi, CNF3));
+
+	return 0;
+}
+
+static int mcp251x_setup(struct net_device *net, struct mcp251x_priv *priv,
+			 struct spi_device *spi)
+{
+	int ret;
+
+	ret = open_candev(net);
+	if (ret) {
+		dev_err(&spi->dev, "unable to set initial baudrate!\n");
+		return ret;
+	}
+
+	/* Enable RX0->RX1 buffer roll over and disable filters */
+	mcp251x_write_bits(spi, RXBCTRL(0),
+			   RXBCTRL_BUKT | RXBCTRL_RXM0 | RXBCTRL_RXM1,
+			   RXBCTRL_BUKT | RXBCTRL_RXM0 | RXBCTRL_RXM1);
+	mcp251x_write_bits(spi, RXBCTRL(1),
+			   RXBCTRL_RXM0 | RXBCTRL_RXM1,
+			   RXBCTRL_RXM0 | RXBCTRL_RXM1);
+	return 0;
+}
+
+static void mcp251x_hw_reset(struct spi_device *spi)
+{
+	struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
+	int ret;
+
+	mutex_lock(&priv->spi_lock);
+
+	priv->spi_tx_buf[0] = INSTRUCTION_RESET;
+
+	ret = spi_write(spi, priv->spi_tx_buf, 1);
+
+	mutex_unlock(&priv->spi_lock);
+
+	if (ret)
+		dev_err(&spi->dev, "reset failed: ret = %d\n", ret);
+	/* Wait for reset to finish */
+	mdelay(10);
+}
+
+static int mcp251x_hw_probe(struct spi_device *spi)
+{
+	int st1, st2;
+
+	mcp251x_hw_reset(spi);
+
+	/*
+	 * Please note that these are "magic values" based on after
+	 * reset defaults taken from data sheet which allows us to see
+	 * if we really have a chip on the bus (we avoid common all
+	 * zeroes or all ones situations)
+	 */
+	st1 = mcp251x_read_reg(spi, CANSTAT) & 0xEE;
+	st2 = mcp251x_read_reg(spi, CANCTRL) & 0x17;
+
+	dev_dbg(&spi->dev, "CANSTAT 0x%02x CANCTRL 0x%02x\n", st1, st2);
+
+	/* Check for power up default values */
+	return (st1 == 0x80 && st2 == 0x07) ? 1 : 0;
+}
+
+static irqreturn_t mcp251x_can_isr(int irq, void *dev_id)
+{
+	struct net_device *net = (struct net_device *)dev_id;
+	struct mcp251x_priv *priv = netdev_priv(net);
+
+	/* Schedule bottom half */
+	if (!work_pending(&priv->irq_work))
+		queue_work(priv->wq, &priv->irq_work);
+
+	return IRQ_HANDLED;
+}
+
+static int mcp251x_open(struct net_device *net)
+{
+	struct mcp251x_priv *priv = netdev_priv(net);
+	struct spi_device *spi = priv->spi;
+	struct mcp251x_platform_data *pdata = spi->dev.platform_data;
+	int ret;
+
+	if (pdata->transceiver_enable)
+		pdata->transceiver_enable(1);
+
+	priv->force_quit = 0;
+	priv->tx_skb = NULL;
+	priv->tx_len = 0;
+
+	ret = request_irq(spi->irq, mcp251x_can_isr,
+			  IRQF_TRIGGER_FALLING, DEVICE_NAME, net);
+	if (ret) {
+		dev_err(&spi->dev, "failed to acquire irq %d\n", spi->irq);
+		if (pdata->transceiver_enable)
+			pdata->transceiver_enable(0);
+		return ret;
+	}
+
+	mcp251x_hw_wakeup(spi);
+	mcp251x_hw_reset(spi);
+	ret = mcp251x_setup(net, priv, spi);
+	if (ret) {
+		free_irq(spi->irq, net);
+		if (pdata->transceiver_enable)
+			pdata->transceiver_enable(0);
+		return ret;
+	}
+	mcp251x_set_normal_mode(spi);
+	netif_wake_queue(net);
+
+	return 0;
+}
+
+static int mcp251x_stop(struct net_device *net)
+{
+	struct mcp251x_priv *priv = netdev_priv(net);
+	struct spi_device *spi = priv->spi;
+	struct mcp251x_platform_data *pdata = spi->dev.platform_data;
+
+	close_candev(net);
+
+	/* Disable and clear pending interrupts */
+	mcp251x_write_reg(spi, CANINTE, 0x00);
+	mcp251x_write_reg(spi, CANINTF, 0x00);
+
+	priv->force_quit = 1;
+	free_irq(spi->irq, net);
+	flush_workqueue(priv->wq);
+
+	mcp251x_write_reg(spi, TXBCTRL(0), 0);
+	if (priv->tx_skb || priv->tx_len)
+		mcp251x_clean(net);
+
+	mcp251x_hw_sleep(spi);
+
+	if (pdata->transceiver_enable)
+		pdata->transceiver_enable(0);
+
+	priv->can.state = CAN_STATE_STOPPED;
+
+	return 0;
+}
+
+static void mcp251x_tx_work_handler(struct work_struct *ws)
+{
+	struct mcp251x_priv *priv = container_of(ws, struct mcp251x_priv,
+						 tx_work);
+	struct spi_device *spi = priv->spi;
+	struct net_device *net = priv->net;
+	struct can_frame *frame;
+
+	if (priv->tx_skb) {
+		frame = (struct can_frame *)priv->tx_skb->data;
+
+		if (priv->can.state == CAN_STATE_BUS_OFF) {
+			mcp251x_clean(net);
+			netif_wake_queue(net);
+			return;
+		}
+		if (frame->can_dlc > CAN_FRAME_MAX_DATA_LEN)
+			frame->can_dlc = CAN_FRAME_MAX_DATA_LEN;
+		mcp251x_hw_tx(spi, frame, 0);
+		priv->tx_len = 1 + frame->can_dlc;
+		can_put_echo_skb(priv->tx_skb, net, 0);
+		priv->tx_skb = NULL;
+	}
+}
+
+static void mcp251x_irq_work_handler(struct work_struct *ws)
+{
+	struct mcp251x_priv *priv = container_of(ws, struct mcp251x_priv,
+						 irq_work);
+	struct spi_device *spi = priv->spi;
+	struct net_device *net = priv->net;
+	u8 txbnctrl;
+	u8 intf;
+	enum can_state new_state;
+
+	if (priv->after_suspend) {
+		mdelay(10);
+		mcp251x_hw_reset(spi);
+		mcp251x_setup(net, priv, spi);
+		if (priv->after_suspend & AFTER_SUSPEND_RESTART) {
+			mcp251x_set_normal_mode(spi);
+		} else if (priv->after_suspend & AFTER_SUSPEND_UP) {
+			netif_device_attach(net);
+			/* Clean since we lost tx buffer */
+			if (priv->tx_skb || priv->tx_len) {
+				mcp251x_clean(net);
+				netif_wake_queue(net);
+			}
+			mcp251x_set_normal_mode(spi);
+		} else {
+			mcp251x_hw_sleep(spi);
+		}
+		priv->after_suspend = 0;
+	}
+
+	if (priv->can.restart_ms == 0 && priv->can.state == CAN_STATE_BUS_OFF)
+		return;
+
+	while (!priv->force_quit && !freezing(current)) {
+		u8 eflag = mcp251x_read_reg(spi, EFLG);
+		int can_id = 0, data1 = 0;
+
+		mcp251x_write_reg(spi, EFLG, 0x00);
+
+		if (priv->restart_tx) {
+			priv->restart_tx = 0;
+			mcp251x_write_reg(spi, TXBCTRL(0), 0);
+			if (priv->tx_skb || priv->tx_len)
+				mcp251x_clean(net);
+			netif_wake_queue(net);
+			can_id |= CAN_ERR_RESTARTED;
+		}
+
+		if (priv->wake) {
+			/* Wait whilst the device wakes up */
+			mdelay(10);
+			priv->wake = 0;
+		}
+
+		intf = mcp251x_read_reg(spi, CANINTF);
+		mcp251x_write_bits(spi, CANINTF, intf, 0x00);
+
+		/* Update can state */
+		if (eflag & EFLG_TXBO) {
+			new_state = CAN_STATE_BUS_OFF;
+			can_id |= CAN_ERR_BUSOFF;
+		} else if (eflag & EFLG_TXEP) {
+			new_state = CAN_STATE_ERROR_PASSIVE;
+			can_id |= CAN_ERR_CRTL;
+			data1 |= CAN_ERR_CRTL_TX_PASSIVE;
+		} else if (eflag & EFLG_RXEP) {
+			new_state = CAN_STATE_ERROR_PASSIVE;
+			can_id |= CAN_ERR_CRTL;
+			data1 |= CAN_ERR_CRTL_RX_PASSIVE;
+		} else if (eflag & EFLG_TXWAR) {
+			new_state = CAN_STATE_ERROR_WARNING;
+			can_id |= CAN_ERR_CRTL;
+			data1 |= CAN_ERR_CRTL_TX_WARNING;
+		} else if (eflag & EFLG_RXWAR) {
+			new_state = CAN_STATE_ERROR_WARNING;
+			can_id |= CAN_ERR_CRTL;
+			data1 |= CAN_ERR_CRTL_RX_WARNING;
+		} else {
+			new_state = CAN_STATE_ERROR_ACTIVE;
+		}
+
+		/* Update can state statistics */
+		switch (priv->can.state) {
+		case CAN_STATE_ERROR_ACTIVE:
+			if (new_state >= CAN_STATE_ERROR_WARNING &&
+			    new_state <= CAN_STATE_BUS_OFF)
+				priv->can.can_stats.error_warning++;
+		case CAN_STATE_ERROR_WARNING:	/* fallthrough */
+			if (new_state >= CAN_STATE_ERROR_PASSIVE &&
+			    new_state <= CAN_STATE_BUS_OFF)
+				priv->can.can_stats.error_passive++;
+			break;
+		default:
+			break;
+		}
+		priv->can.state = new_state;
+
+		if ((intf & CANINTF_ERRIF) || (can_id & CAN_ERR_RESTARTED)) {
+			struct sk_buff *skb;
+			struct can_frame *frame;
+
+			/* Create error frame */
+			skb = alloc_can_err_skb(net, &frame);
+			if (skb) {
+				/* Set error frame flags based on bus state */
+				frame->can_id = can_id;
+				frame->data[1] = data1;
+
+				/* Update net stats for overflows */
+				if (eflag & (EFLG_RX0OVR | EFLG_RX1OVR)) {
+					if (eflag & EFLG_RX0OVR)
+						net->stats.rx_over_errors++;
+					if (eflag & EFLG_RX1OVR)
+						net->stats.rx_over_errors++;
+					frame->can_id |= CAN_ERR_CRTL;
+					frame->data[1] |=
+						CAN_ERR_CRTL_RX_OVERFLOW;
+				}
+
+				netif_rx(skb);
+			} else {
+				dev_info(&spi->dev,
+					 "cannot allocate error skb\n");
+			}
+		}
+
+		if (priv->can.state == CAN_STATE_BUS_OFF) {
+			if (priv->can.restart_ms == 0) {
+				can_bus_off(net);
+				mcp251x_hw_sleep(spi);
+				return;
+			}
+		}
+
+		if (intf == 0)
+			break;
+
+		if (intf & CANINTF_WAKIF)
+			complete(&priv->awake);
+
+		if (intf & CANINTF_MERRF) {
+			/* If there are pending Tx buffers, restart queue */
+			txbnctrl = mcp251x_read_reg(spi, TXBCTRL(0));
+			if (!(txbnctrl & TXBCTRL_TXREQ)) {
+				if (priv->tx_skb || priv->tx_len)
+					mcp251x_clean(net);
+				netif_wake_queue(net);
+			}
+		}
+
+		if (intf & (CANINTF_TX2IF | CANINTF_TX1IF | CANINTF_TX0IF)) {
+			net->stats.tx_packets++;
+			net->stats.tx_bytes += priv->tx_len - 1;
+			if (priv->tx_len) {
+				can_get_echo_skb(net, 0);
+				priv->tx_len = 0;
+			}
+			netif_wake_queue(net);
+		}
+
+		if (intf & CANINTF_RX0IF)
+			mcp251x_hw_rx(spi, 0);
+
+		if (intf & CANINTF_RX1IF)
+			mcp251x_hw_rx(spi, 1);
+	}
+}
+
+static const struct net_device_ops mcp251x_netdev_ops = {
+	.ndo_open = mcp251x_open,
+	.ndo_stop = mcp251x_stop,
+	.ndo_start_xmit = mcp251x_hard_start_xmit,
+};
+
+static int __devinit mcp251x_can_probe(struct spi_device *spi)
+{
+	struct net_device *net;
+	struct mcp251x_priv *priv;
+	struct mcp251x_platform_data *pdata = spi->dev.platform_data;
+	int ret = -ENODEV;
+
+	if (!pdata)
+		/* Platform data is required for osc freq */
+		goto error_out;
+
+	/* Allocate can/net device */
+	net = alloc_candev(sizeof(struct mcp251x_priv), TX_ECHO_SKB_MAX);
+	if (!net) {
+		ret = -ENOMEM;
+		goto error_alloc;
+	}
+
+	net->netdev_ops = &mcp251x_netdev_ops;
+	net->flags |= IFF_ECHO;
+
+	priv = netdev_priv(net);
+	priv->can.bittiming_const = &mcp251x_bittiming_const;
+	priv->can.do_set_mode = mcp251x_do_set_mode;
+	priv->can.clock.freq = pdata->oscillator_frequency / 2;
+	priv->can.do_set_bittiming = mcp251x_do_set_bittiming;
+	priv->net = net;
+	dev_set_drvdata(&spi->dev, priv);
+
+	priv->spi = spi;
+	mutex_init(&priv->spi_lock);
+
+	/* If requested, allocate DMA buffers */
+	if (mcp251x_enable_dma) {
+		spi->dev.coherent_dma_mask = ~0;
+
+		/*
+		 * Minimum coherent DMA allocation is PAGE_SIZE, so allocate
+		 * that much and share it between Tx and Rx DMA buffers.
+		 */
+		priv->spi_tx_buf = dma_alloc_coherent(&spi->dev,
+						      PAGE_SIZE,
+						      &priv->spi_tx_dma,
+						      GFP_DMA);
+
+		if (priv->spi_tx_buf) {
+			priv->spi_rx_buf = (u8 *)(priv->spi_tx_buf +
+						  (PAGE_SIZE / 2));
+			priv->spi_rx_dma = (dma_addr_t)(priv->spi_tx_dma +
+							(PAGE_SIZE / 2));
+		} else {
+			/* Fall back to non-DMA */
+			mcp251x_enable_dma = 0;
+		}
+	}
+
+	/* Allocate non-DMA buffers */
+	if (!mcp251x_enable_dma) {
+		priv->spi_tx_buf = kmalloc(SPI_TRANSFER_BUF_LEN, GFP_KERNEL);
+		if (!priv->spi_tx_buf) {
+			ret = -ENOMEM;
+			goto error_tx_buf;
+		}
+		priv->spi_rx_buf = kmalloc(SPI_TRANSFER_BUF_LEN, GFP_KERNEL);
+		if (!priv->spi_tx_buf) {
+			ret = -ENOMEM;
+			goto error_rx_buf;
+		}
+	}
+
+	if (pdata->power_enable)
+		pdata->power_enable(1);
+
+	/* Call out to platform specific setup */
+	if (pdata->board_specific_setup)
+		pdata->board_specific_setup(spi);
+
+	SET_NETDEV_DEV(net, &spi->dev);
+
+	priv->wq = create_freezeable_workqueue("mcp251x_wq");
+
+	INIT_WORK(&priv->tx_work, mcp251x_tx_work_handler);
+	INIT_WORK(&priv->irq_work, mcp251x_irq_work_handler);
+
+	init_completion(&priv->awake);
+
+	/* Configure the SPI bus */
+	spi->mode = SPI_MODE_0;
+	spi->bits_per_word = 8;
+	spi_setup(spi);
+
+	if (!mcp251x_hw_probe(spi)) {
+		dev_info(&spi->dev, "Probe failed\n");
+		goto error_probe;
+	}
+	mcp251x_hw_sleep(spi);
+
+	if (pdata->transceiver_enable)
+		pdata->transceiver_enable(0);
+
+	ret = register_candev(net);
+	if (!ret) {
+		dev_info(&spi->dev, "probed\n");
+		return ret;
+	}
+error_probe:
+	if (!mcp251x_enable_dma)
+		kfree(priv->spi_rx_buf);
+error_rx_buf:
+	if (!mcp251x_enable_dma)
+		kfree(priv->spi_tx_buf);
+error_tx_buf:
+	free_candev(net);
+	if (mcp251x_enable_dma)
+		dma_free_coherent(&spi->dev, PAGE_SIZE,
+				  priv->spi_tx_buf, priv->spi_tx_dma);
+error_alloc:
+	if (pdata->power_enable)
+		pdata->power_enable(0);
+	dev_err(&spi->dev, "probe failed\n");
+error_out:
+	return ret;
+}
+
+static int __devexit mcp251x_can_remove(struct spi_device *spi)
+{
+	struct mcp251x_platform_data *pdata = spi->dev.platform_data;
+	struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
+	struct net_device *net = priv->net;
+
+	unregister_candev(net);
+	free_candev(net);
+
+	priv->force_quit = 1;
+	flush_workqueue(priv->wq);
+	destroy_workqueue(priv->wq);
+
+	if (mcp251x_enable_dma) {
+		dma_free_coherent(&spi->dev, PAGE_SIZE,
+				  priv->spi_tx_buf, priv->spi_tx_dma);
+	} else {
+		kfree(priv->spi_tx_buf);
+		kfree(priv->spi_rx_buf);
+	}
+
+	if (pdata->power_enable)
+		pdata->power_enable(0);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int mcp251x_can_suspend(struct spi_device *spi, pm_message_t state)
+{
+	struct mcp251x_platform_data *pdata = spi->dev.platform_data;
+	struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
+	struct net_device *net = priv->net;
+
+	if (netif_running(net)) {
+		netif_device_detach(net);
+
+		mcp251x_hw_sleep(spi);
+		if (pdata->transceiver_enable)
+			pdata->transceiver_enable(0);
+		priv->after_suspend = AFTER_SUSPEND_UP;
+	} else {
+		priv->after_suspend = AFTER_SUSPEND_DOWN;
+	}
+
+	if (pdata->power_enable) {
+		pdata->power_enable(0);
+		priv->after_suspend |= AFTER_SUSPEND_POWER;
+	}
+
+	return 0;
+}
+
+static int mcp251x_can_resume(struct spi_device *spi)
+{
+	struct mcp251x_platform_data *pdata = spi->dev.platform_data;
+	struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
+
+	if (priv->after_suspend & AFTER_SUSPEND_POWER) {
+		pdata->power_enable(1);
+		queue_work(priv->wq, &priv->irq_work);
+	} else {
+		if (priv->after_suspend & AFTER_SUSPEND_UP) {
+			if (pdata->transceiver_enable)
+				pdata->transceiver_enable(1);
+			queue_work(priv->wq, &priv->irq_work);
+		} else {
+			priv->after_suspend = 0;
+		}
+	}
+	return 0;
+}
+#else
+#define mcp251x_can_suspend NULL
+#define mcp251x_can_resume NULL
+#endif
+
+static struct spi_driver mcp251x_can_driver = {
+	.driver = {
+		.name = DEVICE_NAME,
+		.bus = &spi_bus_type,
+		.owner = THIS_MODULE,
+	},
+
+	.probe = mcp251x_can_probe,
+	.remove = __devexit_p(mcp251x_can_remove),
+	.suspend = mcp251x_can_suspend,
+	.resume = mcp251x_can_resume,
+};
+
+static int __init mcp251x_can_init(void)
+{
+	return spi_register_driver(&mcp251x_can_driver);
+}
+
+static void __exit mcp251x_can_exit(void)
+{
+	spi_unregister_driver(&mcp251x_can_driver);
+}
+
+module_init(mcp251x_can_init);
+module_exit(mcp251x_can_exit);
+
+MODULE_AUTHOR("Chris Elston <[e-mail]>, "
+	      "Christian Pellegrin <[e-mail]>");
+MODULE_DESCRIPTION("Microchip 251x CAN driver");
+MODULE_LICENSE("GPL v2");

include/linux/can/platform/mcp251x.h

···
+#ifndef __CAN_PLATFORM_MCP251X_H__
+#define __CAN_PLATFORM_MCP251X_H__
+
+/*
+ *
+ * CAN bus driver for Microchip 251x CAN Controller with SPI Interface
+ *
+ */
+
+#include <linux/spi/spi.h>
+
+/**
+ * struct mcp251x_platform_data - MCP251X SPI CAN controller platform data
+ * @oscillator_frequency:       - oscillator frequency in Hz
+ * @model:                      - actual type of chip
+ * @board_specific_setup:       - called before probing the chip (power,reset)
+ * @transceiver_enable:         - called to power on/off the transceiver
+ * @power_enable:               - called to power on/off the mcp *and* the
+ *                                transceiver
+ *
+ * Please note that you should define power_enable or transceiver_enable or
+ * none of them. Defining both of them is no use.
+ *
+ */
+
+struct mcp251x_platform_data {
+	unsigned long oscillator_frequency;
+	int model;
+#define CAN_MCP251X_MCP2510 0
+#define CAN_MCP251X_MCP2515 1
+	int (*board_specific_setup)(struct spi_device *spi);
+	int (*transceiver_enable)(int enable);
+	int (*power_enable) (int enable);
+};
+
+#endif /* __CAN_PLATFORM_MCP251X_H__ */