can: add TI CAN (HECC) driver

TI HECC (High End CAN Controller) module is found on many TI devices. It
has 32 hardware mailboxes with full implementation of CAN protocol 2.0B
with bus speeds up to 1Mbps. Specifications of the module are available
on TI web <http://www.ti.com>

Signed-off-by: Anant Gole <anantgole@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 1014 insertions, 0 deletions

diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
index df32c109b7ac..26d77cc0ded7 100644
--- a/drivers/net/can/Kconfig
+++ b/drivers/net/can/Kconfig
@@ -95,6 +95,13 @@ config CAN_AT91
 	---help---
 	  This is a driver for the SoC CAN controller in Atmel's AT91SAM9263.
 
+config CAN_TI_HECC
+	depends on CAN_DEV && ARCH_OMAP3
+	tristate "TI High End CAN Controller"
+	---help---
+	  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_DEBUG_DEVICES
 	bool "CAN devices debugging messages"
 	depends on CAN
diff --git a/drivers/net/can/Makefile b/drivers/net/can/Makefile
index 0dea62721f2f..31f4ab5df28b 100644
--- a/drivers/net/can/Makefile
+++ b/drivers/net/can/Makefile
@@ -11,5 +11,6 @@ obj-y				+= usb/
 
 obj-$(CONFIG_CAN_SJA1000)	+= sja1000/
 obj-$(CONFIG_CAN_AT91)		+= at91_can.o
+obj-$(CONFIG_CAN_TI_HECC)	+= ti_hecc.o
 
 ccflags-$(CONFIG_CAN_DEBUG_DEVICES) := -DDEBUG
diff --git a/drivers/net/can/ti_hecc.c b/drivers/net/can/ti_hecc.c
new file mode 100644
index 000000000000..814e6c5c6386
--- /dev/null
+++ b/drivers/net/can/ti_hecc.c
@@ -0,0 +1,1006 @@
+/*
+ * TI HECC (CAN) device driver
+ *
+ * This driver supports TI's HECC (High End CAN Controller module) and the
+ * specs for the same is available at <http://www.ti.com>
+ *
+ * Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.com/
+ *
+ * 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 version 2.
+ *
+ * This program is distributed as is WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+/*
+ * Your platform definitions should specify module ram offsets and interrupt
+ * number to use as follows:
+ *
+ * static struct ti_hecc_platform_data am3517_evm_hecc_pdata = {
+ *         .scc_hecc_offset        = 0,
+ *         .scc_ram_offset         = 0x3000,
+ *         .hecc_ram_offset        = 0x3000,
+ *         .mbx_offset             = 0x2000,
+ *         .int_line               = 0,
+ *         .revision               = 1,
+ * };
+ *
+ * Please see include/can/platform/ti_hecc.h for description of above fields
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/interrupt.h>
+#include <linux/errno.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+
+#include <linux/can.h>
+#include <linux/can/dev.h>
+#include <linux/can/error.h>
+#include <linux/can/platform/ti_hecc.h>
+
+#define DRV_NAME "ti_hecc"
+#define HECC_MODULE_VERSION     "0.7"
+MODULE_VERSION(HECC_MODULE_VERSION);
+#define DRV_DESC "TI High End CAN Controller Driver " HECC_MODULE_VERSION
+
+/* TX / RX Mailbox Configuration */
+#define HECC_MAX_MAILBOXES	32	/* hardware mailboxes - do not change */
+#define MAX_TX_PRIO		0x3F	/* hardware value - do not change */
+
+/*
+ * Important Note: TX mailbox configuration
+ * TX mailboxes should be restricted to the number of SKB buffers to avoid
+ * maintaining SKB buffers separately. TX mailboxes should be a power of 2
+ * for the mailbox logic to work.  Top mailbox numbers are reserved for RX
+ * and lower mailboxes for TX.
+ *
+ * HECC_MAX_TX_MBOX	HECC_MB_TX_SHIFT
+ * 4 (default)		2
+ * 8			3
+ * 16			4
+ */
+#define HECC_MB_TX_SHIFT	2 /* as per table above */
+#define HECC_MAX_TX_MBOX	BIT(HECC_MB_TX_SHIFT)
+
+#if (HECC_MAX_TX_MBOX > CAN_ECHO_SKB_MAX)
+#error "HECC: MAX TX mailboxes should be equal or less than CAN_ECHO_SKB_MAX"
+#endif
+
+#define HECC_TX_PRIO_SHIFT	(HECC_MB_TX_SHIFT)
+#define HECC_TX_PRIO_MASK	(MAX_TX_PRIO << HECC_MB_TX_SHIFT)
+#define HECC_TX_MB_MASK		(HECC_MAX_TX_MBOX - 1)
+#define HECC_TX_MASK		((HECC_MAX_TX_MBOX - 1) | HECC_TX_PRIO_MASK)
+#define HECC_TX_MBOX_MASK	(~(BIT(HECC_MAX_TX_MBOX) - 1))
+#define HECC_DEF_NAPI_WEIGHT	HECC_MAX_RX_MBOX
+
+/*
+ * Important Note: RX mailbox configuration
+ * RX mailboxes are further logically split into two - main and buffer
+ * mailboxes. The goal is to get all packets into main mailboxes as
+ * driven by mailbox number and receive priority (higher to lower) and
+ * buffer mailboxes are used to receive pkts while main mailboxes are being
+ * processed. This ensures in-order packet reception.
+ *
+ * Here are the recommended values for buffer mailbox. Note that RX mailboxes
+ * start after TX mailboxes:
+ *
+ * HECC_MAX_RX_MBOX		HECC_RX_BUFFER_MBOX	No of buffer mailboxes
+ * 28				12			8
+ * 16				20			4
+ */
+
+#define HECC_MAX_RX_MBOX	(HECC_MAX_MAILBOXES - HECC_MAX_TX_MBOX)
+#define HECC_RX_BUFFER_MBOX	12 /* as per table above */
+#define HECC_RX_FIRST_MBOX	(HECC_MAX_MAILBOXES - 1)
+#define HECC_RX_HIGH_MBOX_MASK	(~(BIT(HECC_RX_BUFFER_MBOX) - 1))
+
+/* TI HECC module registers */
+#define HECC_CANME		0x0	/* Mailbox enable */
+#define HECC_CANMD		0x4	/* Mailbox direction */
+#define HECC_CANTRS		0x8	/* Transmit request set */
+#define HECC_CANTRR		0xC	/* Transmit request */
+#define HECC_CANTA		0x10	/* Transmission acknowledge */
+#define HECC_CANAA		0x14	/* Abort acknowledge */
+#define HECC_CANRMP		0x18	/* Receive message pending */
+#define HECC_CANRML		0x1C	/* Remote message lost */
+#define HECC_CANRFP		0x20	/* Remote frame pending */
+#define HECC_CANGAM		0x24	/* SECC only:Global acceptance mask */
+#define HECC_CANMC		0x28	/* Master control */
+#define HECC_CANBTC		0x2C	/* Bit timing configuration */
+#define HECC_CANES		0x30	/* Error and status */
+#define HECC_CANTEC		0x34	/* Transmit error counter */
+#define HECC_CANREC		0x38	/* Receive error counter */
+#define HECC_CANGIF0		0x3C	/* Global interrupt flag 0 */
+#define HECC_CANGIM		0x40	/* Global interrupt mask */
+#define HECC_CANGIF1		0x44	/* Global interrupt flag 1 */
+#define HECC_CANMIM		0x48	/* Mailbox interrupt mask */
+#define HECC_CANMIL		0x4C	/* Mailbox interrupt level */
+#define HECC_CANOPC		0x50	/* Overwrite protection control */
+#define HECC_CANTIOC		0x54	/* Transmit I/O control */
+#define HECC_CANRIOC		0x58	/* Receive I/O control */
+#define HECC_CANLNT		0x5C	/* HECC only: Local network time */
+#define HECC_CANTOC		0x60	/* HECC only: Time-out control */
+#define HECC_CANTOS		0x64	/* HECC only: Time-out status */
+#define HECC_CANTIOCE		0x68	/* SCC only:Enhanced TX I/O control */
+#define HECC_CANRIOCE		0x6C	/* SCC only:Enhanced RX I/O control */
+
+/* Mailbox registers */
+#define HECC_CANMID		0x0
+#define HECC_CANMCF		0x4
+#define HECC_CANMDL		0x8
+#define HECC_CANMDH		0xC
+
+#define HECC_SET_REG		0xFFFFFFFF
+#define HECC_CANID_MASK		0x3FF	/* 18 bits mask for extended id's */
+#define HECC_CCE_WAIT_COUNT     100	/* Wait for ~1 sec for CCE bit */
+
+#define HECC_CANMC_SCM		BIT(13)	/* SCC compat mode */
+#define HECC_CANMC_CCR		BIT(12)	/* Change config request */
+#define HECC_CANMC_PDR		BIT(11)	/* Local Power down - for sleep mode */
+#define HECC_CANMC_ABO		BIT(7)	/* Auto Bus On */
+#define HECC_CANMC_STM		BIT(6)	/* Self test mode - loopback */
+#define HECC_CANMC_SRES		BIT(5)	/* Software reset */
+
+#define HECC_CANTIOC_EN		BIT(3)	/* Enable CAN TX I/O pin */
+#define HECC_CANRIOC_EN		BIT(3)	/* Enable CAN RX I/O pin */
+
+#define HECC_CANMID_IDE		BIT(31)	/* Extended frame format */
+#define HECC_CANMID_AME		BIT(30)	/* Acceptance mask enable */
+#define HECC_CANMID_AAM		BIT(29)	/* Auto answer mode */
+
+#define HECC_CANES_FE		BIT(24)	/* form error */
+#define HECC_CANES_BE		BIT(23)	/* bit error */
+#define HECC_CANES_SA1		BIT(22)	/* stuck at dominant error */
+#define HECC_CANES_CRCE		BIT(21)	/* CRC error */
+#define HECC_CANES_SE		BIT(20)	/* stuff bit error */
+#define HECC_CANES_ACKE		BIT(19)	/* ack error */
+#define HECC_CANES_BO		BIT(18)	/* Bus off status */
+#define HECC_CANES_EP		BIT(17)	/* Error passive status */
+#define HECC_CANES_EW		BIT(16)	/* Error warning status */
+#define HECC_CANES_SMA		BIT(5)	/* suspend mode ack */
+#define HECC_CANES_CCE		BIT(4)	/* Change config enabled */
+#define HECC_CANES_PDA		BIT(3)	/* Power down mode ack */
+
+#define HECC_CANBTC_SAM		BIT(7)	/* sample points */
+
+#define HECC_BUS_ERROR		(HECC_CANES_FE | HECC_CANES_BE |\
+				HECC_CANES_CRCE | HECC_CANES_SE |\
+				HECC_CANES_ACKE)
+
+#define HECC_CANMCF_RTR		BIT(4)	/* Remote transmit request */
+
+#define HECC_CANGIF_MAIF	BIT(17)	/* Message alarm interrupt */
+#define HECC_CANGIF_TCOIF	BIT(16) /* Timer counter overflow int */
+#define HECC_CANGIF_GMIF	BIT(15)	/* Global mailbox interrupt */
+#define HECC_CANGIF_AAIF	BIT(14)	/* Abort ack interrupt */
+#define HECC_CANGIF_WDIF	BIT(13)	/* Write denied interrupt */
+#define HECC_CANGIF_WUIF	BIT(12)	/* Wake up interrupt */
+#define HECC_CANGIF_RMLIF	BIT(11)	/* Receive message lost interrupt */
+#define HECC_CANGIF_BOIF	BIT(10)	/* Bus off interrupt */
+#define HECC_CANGIF_EPIF	BIT(9)	/* Error passive interrupt */
+#define HECC_CANGIF_WLIF	BIT(8)	/* Warning level interrupt */
+#define HECC_CANGIF_MBOX_MASK	0x1F	/* Mailbox number mask */
+#define HECC_CANGIM_I1EN	BIT(1)	/* Int line 1 enable */
+#define HECC_CANGIM_I0EN	BIT(0)	/* Int line 0 enable */
+#define HECC_CANGIM_DEF_MASK	0x700	/* only busoff/warning/passive */
+#define HECC_CANGIM_SIL		BIT(2)	/* system interrupts to int line 1 */
+
+/* CAN Bittiming constants as per HECC specs */
+static struct can_bittiming_const ti_hecc_bittiming_const = {
+	.name = DRV_NAME,
+	.tseg1_min = 1,
+	.tseg1_max = 16,
+	.tseg2_min = 1,
+	.tseg2_max = 8,
+	.sjw_max = 4,
+	.brp_min = 1,
+	.brp_max = 256,
+	.brp_inc = 1,
+};
+
+struct ti_hecc_priv {
+	struct can_priv can;	/* MUST be first member/field */
+	struct napi_struct napi;
+	struct net_device *ndev;
+	struct clk *clk;
+	void __iomem *base;
+	u32 scc_ram_offset;
+	u32 hecc_ram_offset;
+	u32 mbx_offset;
+	u32 int_line;
+	spinlock_t mbx_lock; /* CANME register needs protection */
+	u32 tx_head;
+	u32 tx_tail;
+	u32 rx_next;
+};
+
+static inline int get_tx_head_mb(struct ti_hecc_priv *priv)
+{
+	return priv->tx_head & HECC_TX_MB_MASK;
+}
+
+static inline int get_tx_tail_mb(struct ti_hecc_priv *priv)
+{
+	return priv->tx_tail & HECC_TX_MB_MASK;
+}
+
+static inline int get_tx_head_prio(struct ti_hecc_priv *priv)
+{
+	return (priv->tx_head >> HECC_TX_PRIO_SHIFT) & MAX_TX_PRIO;
+}
+
+static inline void hecc_write_lam(struct ti_hecc_priv *priv, u32 mbxno, u32 val)
+{
+	__raw_writel(val, priv->base + priv->hecc_ram_offset + mbxno * 4);
+}
+
+static inline void hecc_write_mbx(struct ti_hecc_priv *priv, u32 mbxno,
+	u32 reg, u32 val)
+{
+	__raw_writel(val, priv->base + priv->mbx_offset + mbxno * 0x10 +
+			reg);
+}
+
+static inline u32 hecc_read_mbx(struct ti_hecc_priv *priv, u32 mbxno, u32 reg)
+{
+	return __raw_readl(priv->base + priv->mbx_offset + mbxno * 0x10 +
+			reg);
+}
+
+static inline void hecc_write(struct ti_hecc_priv *priv, u32 reg, u32 val)
+{
+	__raw_writel(val, priv->base + reg);
+}
+
+static inline u32 hecc_read(struct ti_hecc_priv *priv, int reg)
+{
+	return __raw_readl(priv->base + reg);
+}
+
+static inline void hecc_set_bit(struct ti_hecc_priv *priv, int reg,
+	u32 bit_mask)
+{
+	hecc_write(priv, reg, hecc_read(priv, reg) | bit_mask);
+}
+
+static inline void hecc_clear_bit(struct ti_hecc_priv *priv, int reg,
+	u32 bit_mask)
+{
+	hecc_write(priv, reg, hecc_read(priv, reg) & ~bit_mask);
+}
+
+static inline u32 hecc_get_bit(struct ti_hecc_priv *priv, int reg, u32 bit_mask)
+{
+	return (hecc_read(priv, reg) & bit_mask) ? 1 : 0;
+}
+
+static int ti_hecc_get_state(const struct net_device *ndev,
+	enum can_state *state)
+{
+	struct ti_hecc_priv *priv = netdev_priv(ndev);
+
+	*state = priv->can.state;
+	return 0;
+}
+
+static int ti_hecc_set_btc(struct ti_hecc_priv *priv)
+{
+	struct can_bittiming *bit_timing = &priv->can.bittiming;
+	u32 can_btc;
+
+	can_btc = (bit_timing->phase_seg2 - 1) & 0x7;
+	can_btc |= ((bit_timing->phase_seg1 + bit_timing->prop_seg - 1)
+			& 0xF) << 3;
+	if (priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES) {
+		if (bit_timing->brp > 4)
+			can_btc |= HECC_CANBTC_SAM;
+		else
+			dev_warn(priv->ndev->dev.parent, "WARN: Triple" \
+				"sampling not set due to h/w limitations");
+	}
+	can_btc |= ((bit_timing->sjw - 1) & 0x3) << 8;
+	can_btc |= ((bit_timing->brp - 1) & 0xFF) << 16;
+
+	/* ERM being set to 0 by default meaning resync at falling edge */
+
+	hecc_write(priv, HECC_CANBTC, can_btc);
+	dev_info(priv->ndev->dev.parent, "setting CANBTC=%#x\n", can_btc);
+
+	return 0;
+}
+
+static void ti_hecc_reset(struct net_device *ndev)
+{
+	u32 cnt;
+	struct ti_hecc_priv *priv = netdev_priv(ndev);
+
+	dev_dbg(ndev->dev.parent, "resetting hecc ...\n");
+	hecc_set_bit(priv, HECC_CANMC, HECC_CANMC_SRES);
+
+	/* Set change control request and wait till enabled */
+	hecc_set_bit(priv, HECC_CANMC, HECC_CANMC_CCR);
+
+	/*
+	 * INFO: It has been observed that at times CCE bit may not be
+	 * set and hw seems to be ok even if this bit is not set so
+	 * timing out with a timing of 1ms to respect the specs
+	 */
+	cnt = HECC_CCE_WAIT_COUNT;
+	while (!hecc_get_bit(priv, HECC_CANES, HECC_CANES_CCE) && cnt != 0) {
+		--cnt;
+		udelay(10);
+	}
+
+	/*
+	 * Note: On HECC, BTC can be programmed only in initialization mode, so
+	 * it is expected that the can bittiming parameters are set via ip
+	 * utility before the device is opened
+	 */
+	ti_hecc_set_btc(priv);
+
+	/* Clear CCR (and CANMC register) and wait for CCE = 0 enable */
+	hecc_write(priv, HECC_CANMC, 0);
+
+	/*
+	 * INFO: CAN net stack handles bus off and hence disabling auto-bus-on
+	 * hecc_set_bit(priv, HECC_CANMC, HECC_CANMC_ABO);
+	 */
+
+	/*
+	 * INFO: It has been observed that at times CCE bit may not be
+	 * set and hw seems to be ok even if this bit is not set so
+	 */
+	cnt = HECC_CCE_WAIT_COUNT;
+	while (hecc_get_bit(priv, HECC_CANES, HECC_CANES_CCE) && cnt != 0) {
+		--cnt;
+		udelay(10);
+	}
+
+	/* Enable TX and RX I/O Control pins */
+	hecc_write(priv, HECC_CANTIOC, HECC_CANTIOC_EN);
+	hecc_write(priv, HECC_CANRIOC, HECC_CANRIOC_EN);
+
+	/* Clear registers for clean operation */
+	hecc_write(priv, HECC_CANTA, HECC_SET_REG);
+	hecc_write(priv, HECC_CANRMP, HECC_SET_REG);
+	hecc_write(priv, HECC_CANGIF0, HECC_SET_REG);
+	hecc_write(priv, HECC_CANGIF1, HECC_SET_REG);
+	hecc_write(priv, HECC_CANME, 0);
+	hecc_write(priv, HECC_CANMD, 0);
+
+	/* SCC compat mode NOT supported (and not needed too) */
+	hecc_set_bit(priv, HECC_CANMC, HECC_CANMC_SCM);
+}
+
+static void ti_hecc_start(struct net_device *ndev)
+{
+	struct ti_hecc_priv *priv = netdev_priv(ndev);
+	u32 cnt, mbxno, mbx_mask;
+
+	/* put HECC in initialization mode and set btc */
+	ti_hecc_reset(ndev);
+
+	priv->tx_head = priv->tx_tail = HECC_TX_MASK;
+	priv->rx_next = HECC_RX_FIRST_MBOX;
+
+	/* Enable local and global acceptance mask registers */
+	hecc_write(priv, HECC_CANGAM, HECC_SET_REG);
+
+	/* Prepare configured mailboxes to receive messages */
+	for (cnt = 0; cnt < HECC_MAX_RX_MBOX; cnt++) {
+		mbxno = HECC_MAX_MAILBOXES - 1 - cnt;
+		mbx_mask = BIT(mbxno);
+		hecc_clear_bit(priv, HECC_CANME, mbx_mask);
+		hecc_write_mbx(priv, mbxno, HECC_CANMID, HECC_CANMID_AME);
+		hecc_write_lam(priv, mbxno, HECC_SET_REG);
+		hecc_set_bit(priv, HECC_CANMD, mbx_mask);
+		hecc_set_bit(priv, HECC_CANME, mbx_mask);
+		hecc_set_bit(priv, HECC_CANMIM, mbx_mask);
+	}
+
+	/* Prevent message over-write & Enable interrupts */
+	hecc_write(priv, HECC_CANOPC, HECC_SET_REG);
+	if (priv->int_line) {
+		hecc_write(priv, HECC_CANMIL, HECC_SET_REG);
+		hecc_write(priv, HECC_CANGIM, HECC_CANGIM_DEF_MASK |
+			HECC_CANGIM_I1EN | HECC_CANGIM_SIL);
+	} else {
+		hecc_write(priv, HECC_CANMIL, 0);
+		hecc_write(priv, HECC_CANGIM,
+			HECC_CANGIM_DEF_MASK | HECC_CANGIM_I0EN);
+	}
+	priv->can.state = CAN_STATE_ERROR_ACTIVE;
+}
+
+static void ti_hecc_stop(struct net_device *ndev)
+{
+	struct ti_hecc_priv *priv = netdev_priv(ndev);
+
+	/* Disable interrupts and disable mailboxes */
+	hecc_write(priv, HECC_CANGIM, 0);
+	hecc_write(priv, HECC_CANMIM, 0);
+	hecc_write(priv, HECC_CANME, 0);
+	priv->can.state = CAN_STATE_STOPPED;
+}
+
+static int ti_hecc_do_set_mode(struct net_device *ndev, enum can_mode mode)
+{
+	int ret = 0;
+
+	switch (mode) {
+	case CAN_MODE_START:
+		ti_hecc_start(ndev);
+		netif_wake_queue(ndev);
+		break;
+	default:
+		ret = -EOPNOTSUPP;
+		break;
+	}
+
+	return ret;
+}
+
+/*
+ * ti_hecc_xmit: HECC Transmit
+ *
+ * The transmit mailboxes start from 0 to HECC_MAX_TX_MBOX. In HECC the
+ * priority of the mailbox for tranmission is dependent upon priority setting
+ * field in mailbox registers. The mailbox with highest value in priority field
+ * is transmitted first. Only when two mailboxes have the same value in
+ * priority field the highest numbered mailbox is transmitted first.
+ *
+ * To utilize the HECC priority feature as described above we start with the
+ * highest numbered mailbox with highest priority level and move on to the next
+ * mailbox with the same priority level and so on. Once we loop through all the
+ * transmit mailboxes we choose the next priority level (lower) and so on
+ * until we reach the lowest priority level on the lowest numbered mailbox
+ * when we stop transmission until all mailboxes are transmitted and then
+ * restart at highest numbered mailbox with highest priority.
+ *
+ * Two counters (head and tail) are used to track the next mailbox to transmit
+ * and to track the echo buffer for already transmitted mailbox. The queue
+ * is stopped when all the mailboxes are busy or when there is a priority
+ * value roll-over happens.
+ */
+static netdev_tx_t ti_hecc_xmit(struct sk_buff *skb, struct net_device *ndev)
+{
+	struct ti_hecc_priv *priv = netdev_priv(ndev);
+	struct can_frame *cf = (struct can_frame *)skb->data;
+	u32 mbxno, mbx_mask, data;
+	unsigned long flags;
+
+	mbxno = get_tx_head_mb(priv);
+	mbx_mask = BIT(mbxno);
+	spin_lock_irqsave(&priv->mbx_lock, flags);
+	if (unlikely(hecc_read(priv, HECC_CANME) & mbx_mask)) {
+		spin_unlock_irqrestore(&priv->mbx_lock, flags);
+		netif_stop_queue(ndev);
+		dev_err(priv->ndev->dev.parent,
+			"BUG: TX mbx not ready tx_head=%08X, tx_tail=%08X\n",
+			priv->tx_head, priv->tx_tail);
+		return NETDEV_TX_BUSY;
+	}
+	spin_unlock_irqrestore(&priv->mbx_lock, flags);
+
+	/* Prepare mailbox for transmission */
+	data = min_t(u8, cf->can_dlc, 8);
+	if (cf->can_id & CAN_RTR_FLAG) /* Remote transmission request */
+		data |= HECC_CANMCF_RTR;
+	data |= get_tx_head_prio(priv) << 8;
+	hecc_write_mbx(priv, mbxno, HECC_CANMCF, data);
+
+	if (cf->can_id & CAN_EFF_FLAG) /* Extended frame format */
+		data = (cf->can_id & CAN_EFF_MASK) | HECC_CANMID_IDE;
+	else /* Standard frame format */
+		data = (cf->can_id & CAN_SFF_MASK) << 18;
+	hecc_write_mbx(priv, mbxno, HECC_CANMID, data);
+	hecc_write_mbx(priv, mbxno, HECC_CANMDL,
+		be32_to_cpu(*(u32 *)(cf->data)));
+	if (cf->can_dlc > 4)
+		hecc_write_mbx(priv, mbxno, HECC_CANMDH,
+			be32_to_cpu(*(u32 *)(cf->data + 4)));
+	else
+		*(u32 *)(cf->data + 4) = 0;
+	can_put_echo_skb(skb, ndev, mbxno);
+
+	spin_lock_irqsave(&priv->mbx_lock, flags);
+	--priv->tx_head;
+	if ((hecc_read(priv, HECC_CANME) & BIT(get_tx_head_mb(priv))) ||
+		(priv->tx_head & HECC_TX_MASK) == HECC_TX_MASK) {
+		netif_stop_queue(ndev);
+	}
+	hecc_set_bit(priv, HECC_CANME, mbx_mask);
+	spin_unlock_irqrestore(&priv->mbx_lock, flags);
+
+	hecc_clear_bit(priv, HECC_CANMD, mbx_mask);
+	hecc_set_bit(priv, HECC_CANMIM, mbx_mask);
+	hecc_write(priv, HECC_CANTRS, mbx_mask);
+
+	return NETDEV_TX_OK;
+}
+
+static int ti_hecc_rx_pkt(struct ti_hecc_priv *priv, int mbxno)
+{
+	struct net_device_stats *stats = &priv->ndev->stats;
+	struct can_frame *cf;
+	struct sk_buff *skb;
+	u32 data, mbx_mask;
+	unsigned long flags;
+
+	skb = netdev_alloc_skb(priv->ndev, sizeof(struct can_frame));
+	if (!skb) {
+		if (printk_ratelimit())
+			dev_err(priv->ndev->dev.parent,
+				"ti_hecc_rx_pkt: netdev_alloc_skb() failed\n");
+		return -ENOMEM;
+	}
+	skb->protocol = __constant_htons(ETH_P_CAN);
+	skb->ip_summed = CHECKSUM_UNNECESSARY;
+
+	mbx_mask = BIT(mbxno);
+	cf = (struct can_frame *)skb_put(skb, sizeof(struct can_frame));
+	data = hecc_read_mbx(priv, mbxno, HECC_CANMID);
+	if (data & HECC_CANMID_IDE)
+		cf->can_id = (data & CAN_EFF_MASK) | CAN_EFF_FLAG;
+	else
+		cf->can_id = (data >> 18) & CAN_SFF_MASK;
+	data = hecc_read_mbx(priv, mbxno, HECC_CANMCF);
+	if (data & HECC_CANMCF_RTR)
+		cf->can_id |= CAN_RTR_FLAG;
+	cf->can_dlc = data & 0xF;
+	data = hecc_read_mbx(priv, mbxno, HECC_CANMDL);
+	*(u32 *)(cf->data) = cpu_to_be32(data);
+	if (cf->can_dlc > 4) {
+		data = hecc_read_mbx(priv, mbxno, HECC_CANMDH);
+		*(u32 *)(cf->data + 4) = cpu_to_be32(data);
+	} else {
+		*(u32 *)(cf->data + 4) = 0;
+	}
+	spin_lock_irqsave(&priv->mbx_lock, flags);
+	hecc_clear_bit(priv, HECC_CANME, mbx_mask);
+	hecc_write(priv, HECC_CANRMP, mbx_mask);
+	/* enable mailbox only if it is part of rx buffer mailboxes */
+	if (priv->rx_next < HECC_RX_BUFFER_MBOX)
+		hecc_set_bit(priv, HECC_CANME, mbx_mask);
+	spin_unlock_irqrestore(&priv->mbx_lock, flags);
+
+	stats->rx_bytes += cf->can_dlc;
+	netif_receive_skb(skb);
+	stats->rx_packets++;
+
+	return 0;
+}
+
+/*
+ * ti_hecc_rx_poll - HECC receive pkts
+ *
+ * The receive mailboxes start from highest numbered mailbox till last xmit
+ * mailbox. On CAN frame reception the hardware places the data into highest
+ * numbered mailbox that matches the CAN ID filter. Since all receive mailboxes
+ * have same filtering (ALL CAN frames) packets will arrive in the highest
+ * available RX mailbox and we need to ensure in-order packet reception.
+ *
+ * To ensure the packets are received in the right order we logically divide
+ * the RX mailboxes into main and buffer mailboxes. Packets are received as per
+ * mailbox priotity (higher to lower) in the main bank and once it is full we
+ * disable further reception into main mailboxes. While the main mailboxes are
+ * processed in NAPI, further packets are received in buffer mailboxes.
+ *
+ * We maintain a RX next mailbox counter to process packets and once all main
+ * mailboxe packets are passed to the upper stack we enable all of them but
+ * continue to process packets received in buffer mailboxes. With each packet
+ * received from buffer mailbox we enable it immediately so as to handle the
+ * overflow from higher mailboxes.
+ */
+static int ti_hecc_rx_poll(struct napi_struct *napi, int quota)
+{
+	struct net_device *ndev = napi->dev;
+	struct ti_hecc_priv *priv = netdev_priv(ndev);
+	u32 num_pkts = 0;
+	u32 mbx_mask;
+	unsigned long pending_pkts, flags;
+
+	if (!netif_running(ndev))
+		return 0;
+
+	while ((pending_pkts = hecc_read(priv, HECC_CANRMP)) &&
+		num_pkts < quota) {
+		mbx_mask = BIT(priv->rx_next); /* next rx mailbox to process */
+		if (mbx_mask & pending_pkts) {
+			if (ti_hecc_rx_pkt(priv, priv->rx_next) < 0)
+				return num_pkts;
+			++num_pkts;
+		} else if (priv->rx_next > HECC_RX_BUFFER_MBOX) {
+			break; /* pkt not received yet */
+		}
+		--priv->rx_next;
+		if (priv->rx_next == HECC_RX_BUFFER_MBOX) {
+			/* enable high bank mailboxes */
+			spin_lock_irqsave(&priv->mbx_lock, flags);
+			mbx_mask = hecc_read(priv, HECC_CANME);
+			mbx_mask |= HECC_RX_HIGH_MBOX_MASK;
+			hecc_write(priv, HECC_CANME, mbx_mask);
+			spin_unlock_irqrestore(&priv->mbx_lock, flags);
+		} else if (priv->rx_next == HECC_MAX_TX_MBOX - 1) {
+			priv->rx_next = HECC_RX_FIRST_MBOX;
+			break;
+		}
+	}
+
+	/* Enable packet interrupt if all pkts are handled */
+	if (hecc_read(priv, HECC_CANRMP) == 0) {
+		napi_complete(napi);
+		/* Re-enable RX mailbox interrupts */
+		mbx_mask = hecc_read(priv, HECC_CANMIM);
+		mbx_mask |= HECC_TX_MBOX_MASK;
+		hecc_write(priv, HECC_CANMIM, mbx_mask);
+	}
+
+	return num_pkts;
+}
+
+static int ti_hecc_error(struct net_device *ndev, int int_status,
+	int err_status)
+{
+	struct ti_hecc_priv *priv = netdev_priv(ndev);
+	struct net_device_stats *stats = &ndev->stats;
+	struct can_frame *cf;
+	struct sk_buff *skb;
+
+	/* propogate the error condition to the can stack */
+	skb = netdev_alloc_skb(ndev, sizeof(struct can_frame));
+	if (!skb) {
+		if (printk_ratelimit())
+			dev_err(priv->ndev->dev.parent,
+				"ti_hecc_error: netdev_alloc_skb() failed\n");
+		return -ENOMEM;
+	}
+	skb->protocol = __constant_htons(ETH_P_CAN);
+	skb->ip_summed = CHECKSUM_UNNECESSARY;
+	cf = (struct can_frame *)skb_put(skb, sizeof(struct can_frame));
+	memset(cf, 0, sizeof(struct can_frame));
+	cf->can_id = CAN_ERR_FLAG;
+	cf->can_dlc = CAN_ERR_DLC;
+
+	if (int_status & HECC_CANGIF_WLIF) { /* warning level int */
+		if ((int_status & HECC_CANGIF_BOIF) == 0) {
+			priv->can.state = CAN_STATE_ERROR_WARNING;
+			++priv->can.can_stats.error_warning;
+			cf->can_id |= CAN_ERR_CRTL;
+			if (hecc_read(priv, HECC_CANTEC) > 96)
+				cf->data[1] |= CAN_ERR_CRTL_TX_WARNING;
+			if (hecc_read(priv, HECC_CANREC) > 96)
+				cf->data[1] |= CAN_ERR_CRTL_RX_WARNING;
+		}
+		hecc_set_bit(priv, HECC_CANES, HECC_CANES_EW);
+		dev_dbg(priv->ndev->dev.parent, "Error Warning interrupt\n");
+		hecc_clear_bit(priv, HECC_CANMC, HECC_CANMC_CCR);
+	}
+
+	if (int_status & HECC_CANGIF_EPIF) { /* error passive int */
+		if ((int_status & HECC_CANGIF_BOIF) == 0) {
+			priv->can.state = CAN_STATE_ERROR_PASSIVE;
+			++priv->can.can_stats.error_passive;
+			cf->can_id |= CAN_ERR_CRTL;
+			if (hecc_read(priv, HECC_CANTEC) > 127)
+				cf->data[1] |= CAN_ERR_CRTL_TX_PASSIVE;
+			if (hecc_read(priv, HECC_CANREC) > 127)
+				cf->data[1] |= CAN_ERR_CRTL_RX_PASSIVE;
+		}
+		hecc_set_bit(priv, HECC_CANES, HECC_CANES_EP);
+		dev_dbg(priv->ndev->dev.parent, "Error passive interrupt\n");
+		hecc_clear_bit(priv, HECC_CANMC, HECC_CANMC_CCR);
+	}
+
+	/*
+	 * Need to check busoff condition in error status register too to
+	 * ensure warning interrupts don't hog the system
+	 */
+	if ((int_status & HECC_CANGIF_BOIF) || (err_status & HECC_CANES_BO)) {
+		priv->can.state = CAN_STATE_BUS_OFF;
+		cf->can_id |= CAN_ERR_BUSOFF;
+		hecc_set_bit(priv, HECC_CANES, HECC_CANES_BO);
+		hecc_clear_bit(priv, HECC_CANMC, HECC_CANMC_CCR);
+		/* Disable all interrupts in bus-off to avoid int hog */
+		hecc_write(priv, HECC_CANGIM, 0);
+		can_bus_off(ndev);
+	}
+
+	if (err_status & HECC_BUS_ERROR) {
+		++priv->can.can_stats.bus_error;
+		cf->can_id |= CAN_ERR_BUSERROR | CAN_ERR_PROT;
+		cf->data[2] |= CAN_ERR_PROT_UNSPEC;
+		if (err_status & HECC_CANES_FE) {
+			hecc_set_bit(priv, HECC_CANES, HECC_CANES_FE);
+			cf->data[2] |= CAN_ERR_PROT_FORM;
+		}
+		if (err_status & HECC_CANES_BE) {
+			hecc_set_bit(priv, HECC_CANES, HECC_CANES_BE);
+			cf->data[2] |= CAN_ERR_PROT_BIT;
+		}
+		if (err_status & HECC_CANES_SE) {
+			hecc_set_bit(priv, HECC_CANES, HECC_CANES_SE);
+			cf->data[2] |= CAN_ERR_PROT_STUFF;
+		}
+		if (err_status & HECC_CANES_CRCE) {
+			hecc_set_bit(priv, HECC_CANES, HECC_CANES_CRCE);
+			cf->data[2] |= CAN_ERR_PROT_LOC_CRC_SEQ |
+					CAN_ERR_PROT_LOC_CRC_DEL;
+		}
+		if (err_status & HECC_CANES_ACKE) {
+			hecc_set_bit(priv, HECC_CANES, HECC_CANES_ACKE);
+			cf->data[2] |= CAN_ERR_PROT_LOC_ACK |
+					CAN_ERR_PROT_LOC_ACK_DEL;
+		}
+	}
+
+	netif_receive_skb(skb);
+	stats->rx_packets++;
+	stats->rx_bytes += cf->can_dlc;
+	return 0;
+}
+
+static irqreturn_t ti_hecc_interrupt(int irq, void *dev_id)
+{
+	struct net_device *ndev = (struct net_device *)dev_id;
+	struct ti_hecc_priv *priv = netdev_priv(ndev);
+	struct net_device_stats *stats = &ndev->stats;
+	u32 mbxno, mbx_mask, int_status, err_status;
+	unsigned long ack, flags;
+
+	int_status = hecc_read(priv,
+		(priv->int_line) ? HECC_CANGIF1 : HECC_CANGIF0);
+
+	if (!int_status)
+		return IRQ_NONE;
+
+	err_status = hecc_read(priv, HECC_CANES);
+	if (err_status & (HECC_BUS_ERROR | HECC_CANES_BO |
+		HECC_CANES_EP | HECC_CANES_EW))
+			ti_hecc_error(ndev, int_status, err_status);
+
+	if (int_status & HECC_CANGIF_GMIF) {
+		while (priv->tx_tail - priv->tx_head > 0) {
+			mbxno = get_tx_tail_mb(priv);
+			mbx_mask = BIT(mbxno);
+			if (!(mbx_mask & hecc_read(priv, HECC_CANTA)))
+				break;
+			hecc_clear_bit(priv, HECC_CANMIM, mbx_mask);
+			hecc_write(priv, HECC_CANTA, mbx_mask);
+			spin_lock_irqsave(&priv->mbx_lock, flags);
+			hecc_clear_bit(priv, HECC_CANME, mbx_mask);
+			spin_unlock_irqrestore(&priv->mbx_lock, flags);
+			stats->tx_bytes += hecc_read_mbx(priv, mbxno,
+						HECC_CANMCF) & 0xF;
+			stats->tx_packets++;
+			can_get_echo_skb(ndev, mbxno);
+			--priv->tx_tail;
+		}
+
+		/* restart queue if wrap-up or if queue stalled on last pkt */
+		if (((priv->tx_head == priv->tx_tail) &&
+		((priv->tx_head & HECC_TX_MASK) != HECC_TX_MASK)) ||
+		(((priv->tx_tail & HECC_TX_MASK) == HECC_TX_MASK) &&
+		((priv->tx_head & HECC_TX_MASK) == HECC_TX_MASK)))
+			netif_wake_queue(ndev);
+
+		/* Disable RX mailbox interrupts and let NAPI reenable them */
+		if (hecc_read(priv, HECC_CANRMP)) {
+			ack = hecc_read(priv, HECC_CANMIM);
+			ack &= BIT(HECC_MAX_TX_MBOX) - 1;
+			hecc_write(priv, HECC_CANMIM, ack);
+			napi_schedule(&priv->napi);
+		}
+	}
+
+	/* clear all interrupt conditions - read back to avoid spurious ints */
+	if (priv->int_line) {
+		hecc_write(priv, HECC_CANGIF1, HECC_SET_REG);
+		int_status = hecc_read(priv, HECC_CANGIF1);
+	} else {
+		hecc_write(priv, HECC_CANGIF0, HECC_SET_REG);
+		int_status = hecc_read(priv, HECC_CANGIF0);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int ti_hecc_open(struct net_device *ndev)
+{
+	struct ti_hecc_priv *priv = netdev_priv(ndev);
+	int err;
+
+	err = request_irq(ndev->irq, ti_hecc_interrupt, IRQF_SHARED,
+			ndev->name, ndev);
+	if (err) {
+		dev_err(ndev->dev.parent, "error requesting interrupt\n");
+		return err;
+	}
+
+	/* Open common can device */
+	err = open_candev(ndev);
+	if (err) {
+		dev_err(ndev->dev.parent, "open_candev() failed %d\n", err);
+		free_irq(ndev->irq, ndev);
+		return err;
+	}
+
+	clk_enable(priv->clk);
+	ti_hecc_start(ndev);
+	napi_enable(&priv->napi);
+	netif_start_queue(ndev);
+
+	return 0;
+}
+
+static int ti_hecc_close(struct net_device *ndev)
+{
+	struct ti_hecc_priv *priv = netdev_priv(ndev);
+
+	netif_stop_queue(ndev);
+	napi_disable(&priv->napi);
+	ti_hecc_stop(ndev);
+	free_irq(ndev->irq, ndev);
+	clk_disable(priv->clk);
+	close_candev(ndev);
+
+	return 0;
+}
+
+static const struct net_device_ops ti_hecc_netdev_ops = {
+	.ndo_open		= ti_hecc_open,
+	.ndo_stop		= ti_hecc_close,
+	.ndo_start_xmit		= ti_hecc_xmit,
+};
+
+static int ti_hecc_probe(struct platform_device *pdev)
+{
+	struct net_device *ndev = (struct net_device *)0;
+	struct ti_hecc_priv *priv;
+	struct ti_hecc_platform_data *pdata;
+	struct resource *mem, *irq;
+	void __iomem *addr;
+	int err = -ENODEV;
+
+	pdata = pdev->dev.platform_data;
+	if (!pdata) {
+		dev_err(&pdev->dev, "No platform data\n");
+		goto probe_exit;
+	}
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!mem) {
+		dev_err(&pdev->dev, "No mem resources\n");
+		goto probe_exit;
+	}
+	irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	if (!irq) {
+		dev_err(&pdev->dev, "No irq resource\n");
+		goto probe_exit;
+	}
+	if (!request_mem_region(mem->start, resource_size(mem), pdev->name)) {
+		dev_err(&pdev->dev, "HECC region already claimed\n");
+		err = -EBUSY;
+		goto probe_exit;
+	}
+	addr = ioremap(mem->start, resource_size(mem));
+	if (!addr) {
+		dev_err(&pdev->dev, "ioremap failed\n");
+		err = -ENOMEM;
+		goto probe_exit_free_region;
+	}
+
+	ndev = alloc_candev(sizeof(struct ti_hecc_priv));
+	if (!ndev) {
+		dev_err(&pdev->dev, "alloc_candev failed\n");
+		err = -ENOMEM;
+		goto probe_exit_iounmap;
+	}
+
+	priv = netdev_priv(ndev);
+	priv->ndev = ndev;
+	priv->base = addr;
+	priv->scc_ram_offset = pdata->scc_ram_offset;
+	priv->hecc_ram_offset = pdata->hecc_ram_offset;
+	priv->mbx_offset = pdata->mbx_offset;
+	priv->int_line = pdata->int_line;
+
+	priv->can.bittiming_const = &ti_hecc_bittiming_const;
+	priv->can.do_set_mode = ti_hecc_do_set_mode;
+	priv->can.do_get_state = ti_hecc_get_state;
+
+	ndev->irq = irq->start;
+	ndev->flags |= IFF_ECHO;
+	platform_set_drvdata(pdev, ndev);
+	SET_NETDEV_DEV(ndev, &pdev->dev);
+	ndev->netdev_ops = &ti_hecc_netdev_ops;
+
+	priv->clk = clk_get(&pdev->dev, "hecc_ck");
+	if (IS_ERR(priv->clk)) {
+		dev_err(&pdev->dev, "No clock available\n");
+		err = PTR_ERR(priv->clk);
+		priv->clk = NULL;
+		goto probe_exit_candev;
+	}
+	priv->can.clock.freq = clk_get_rate(priv->clk);
+	netif_napi_add(ndev, &priv->napi, ti_hecc_rx_poll,
+		HECC_DEF_NAPI_WEIGHT);
+
+	err = register_candev(ndev);
+	if (err) {
+		dev_err(&pdev->dev, "register_candev() failed\n");
+		goto probe_exit_clk;
+	}
+	dev_info(&pdev->dev, "device registered (reg_base=%p, irq=%u)\n",
+		priv->base, (u32) ndev->irq);
+
+	return 0;
+
+probe_exit_clk:
+	clk_put(priv->clk);
+probe_exit_candev:
+	free_candev(ndev);
+probe_exit_iounmap:
+	iounmap(addr);
+probe_exit_free_region:
+	release_mem_region(mem->start, resource_size(mem));
+probe_exit:
+	return err;
+}
+
+static int __devexit ti_hecc_remove(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct net_device *ndev = platform_get_drvdata(pdev);
+	struct ti_hecc_priv *priv = netdev_priv(ndev);
+
+	clk_put(priv->clk);
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	iounmap(priv->base);
+	release_mem_region(res->start, resource_size(res));
+	unregister_candev(ndev);
+	free_candev(ndev);
+	platform_set_drvdata(pdev, NULL);
+
+	return 0;
+}
+
+/* TI HECC netdevice driver: platform driver structure */
+static struct platform_driver ti_hecc_driver = {
+	.driver = {
+		.name    = DRV_NAME,
+		.owner   = THIS_MODULE,
+	},
+	.probe = ti_hecc_probe,
+	.remove = __devexit_p(ti_hecc_remove),
+};
+
+static int __init ti_hecc_init_driver(void)
+{
+	printk(KERN_INFO DRV_DESC "\n");
+	return platform_driver_register(&ti_hecc_driver);
+}
+module_init(ti_hecc_init_driver);
+
+static void __exit ti_hecc_exit_driver(void)
+{
+	printk(KERN_INFO DRV_DESC " unloaded\n");
+	platform_driver_unregister(&ti_hecc_driver);
+}
+module_exit(ti_hecc_exit_driver);
+
+MODULE_AUTHOR("Anant Gole <anantgole@ti.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION(DRV_DESC);