can: Allwinner A10/A20 CAN Controller support - Kernel module

Kernel module for Allwinner A10/A20 CAN controller.
Signed-off-by: Gerhard Bertelsmann <info@gerhard-bertelsmann.de>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/Kconfig

@@ -129,6 +129,16 @@ config CAN_RCAR
 	  To compile this driver as a module, choose M here: the module will
 	  be called rcar_can.
 
+config CAN_SUN4I
+	tristate "Allwinner A10 CAN controller"
+	depends on MACH_SUN4I || MACH_SUN7I || COMPILE_TEST
+	---help---
+	  Say Y here if you want to use CAN controller found on Allwinner
+	  A10/A20 SoCs.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called sun4i_can.
+
 config CAN_XILINXCAN
 	tristate "Xilinx CAN"
 	depends on ARCH_ZYNQ || ARM64 || MICROBLAZE || COMPILE_TEST

drivers/net/can/Makefile

@@ -27,6 +27,7 @@ obj-$(CONFIG_CAN_FLEXCAN)	+= flexcan.o
 obj-$(CONFIG_PCH_CAN)		+= pch_can.o
 obj-$(CONFIG_CAN_GRCAN)		+= grcan.o
 obj-$(CONFIG_CAN_RCAR)		+= rcar_can.o
+obj-$(CONFIG_CAN_SUN4I)		+= sun4i_can.o
 obj-$(CONFIG_CAN_XILINXCAN)	+= xilinx_can.o
 
 subdir-ccflags-y += -D__CHECK_ENDIAN__

drivers/net/can/sun4i_can.c

+/*
+ * sun4i_can.c - CAN bus controller driver for Allwinner SUN4I&SUN7I based SoCs
+ *
+ * Copyright (C) 2013 Peter Chen
+ * Copyright (C) 2015 Gerhard Bertelsmann
+ * All rights reserved.
+ *
+ * Parts of this software are based on (derived from) the SJA1000 code by:
+ *   Copyright (C) 2014 Oliver Hartkopp <oliver.hartkopp@volkswagen.de>
+ *   Copyright (C) 2007 Wolfgang Grandegger <wg@grandegger.com>
+ *   Copyright (C) 2002-2007 Volkswagen Group Electronic Research
+ *   Copyright (C) 2003 Matthias Brukner, Trajet Gmbh, Rebenring 33,
+ *   38106 Braunschweig, GERMANY
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Volkswagen nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * Alternatively, provided that this notice is retained in full, this
+ * software may be distributed under the terms of the GNU General
+ * Public License ("GPL") version 2, in which case the provisions of the
+ * GPL apply INSTEAD OF those given above.
+ *
+ * The provided data structures and external interfaces from this code
+ * are not restricted to be used by modules with a GPL compatible license.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ */
+
+#include <linux/netdevice.h>
+#include <linux/can.h>
+#include <linux/can/dev.h>
+#include <linux/can/error.h>
+#include <linux/can/led.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+
+#define DRV_NAME "sun4i_can"
+
+/* Registers address (physical base address 0x01C2BC00) */
+#define SUN4I_REG_MSEL_ADDR	0x0000	/* CAN Mode Select */
+#define SUN4I_REG_CMD_ADDR	0x0004	/* CAN Command */
+#define SUN4I_REG_STA_ADDR	0x0008	/* CAN Status */
+#define SUN4I_REG_INT_ADDR	0x000c	/* CAN Interrupt Flag */
+#define SUN4I_REG_INTEN_ADDR	0x0010	/* CAN Interrupt Enable */
+#define SUN4I_REG_BTIME_ADDR	0x0014	/* CAN Bus Timing 0 */
+#define SUN4I_REG_TEWL_ADDR	0x0018	/* CAN Tx Error Warning Limit */
+#define SUN4I_REG_ERRC_ADDR	0x001c	/* CAN Error Counter */
+#define SUN4I_REG_RMCNT_ADDR	0x0020	/* CAN Receive Message Counter */
+#define SUN4I_REG_RBUFSA_ADDR	0x0024	/* CAN Receive Buffer Start Address */
+#define SUN4I_REG_BUF0_ADDR	0x0040	/* CAN Tx/Rx Buffer 0 */
+#define SUN4I_REG_BUF1_ADDR	0x0044	/* CAN Tx/Rx Buffer 1 */
+#define SUN4I_REG_BUF2_ADDR	0x0048	/* CAN Tx/Rx Buffer 2 */
+#define SUN4I_REG_BUF3_ADDR	0x004c	/* CAN Tx/Rx Buffer 3 */
+#define SUN4I_REG_BUF4_ADDR	0x0050	/* CAN Tx/Rx Buffer 4 */
+#define SUN4I_REG_BUF5_ADDR	0x0054	/* CAN Tx/Rx Buffer 5 */
+#define SUN4I_REG_BUF6_ADDR	0x0058	/* CAN Tx/Rx Buffer 6 */
+#define SUN4I_REG_BUF7_ADDR	0x005c	/* CAN Tx/Rx Buffer 7 */
+#define SUN4I_REG_BUF8_ADDR	0x0060	/* CAN Tx/Rx Buffer 8 */
+#define SUN4I_REG_BUF9_ADDR	0x0064	/* CAN Tx/Rx Buffer 9 */
+#define SUN4I_REG_BUF10_ADDR	0x0068	/* CAN Tx/Rx Buffer 10 */
+#define SUN4I_REG_BUF11_ADDR	0x006c	/* CAN Tx/Rx Buffer 11 */
+#define SUN4I_REG_BUF12_ADDR	0x0070	/* CAN Tx/Rx Buffer 12 */
+#define SUN4I_REG_ACPC_ADDR	0x0040	/* CAN Acceptance Code 0 */
+#define SUN4I_REG_ACPM_ADDR	0x0044	/* CAN Acceptance Mask 0 */
+#define SUN4I_REG_RBUF_RBACK_START_ADDR	0x0180	/* CAN transmit buffer start */
+#define SUN4I_REG_RBUF_RBACK_END_ADDR	0x01b0	/* CAN transmit buffer end */
+
+/* Controller Register Description */
+
+/* mode select register (r/w)
+ * offset:0x0000 default:0x0000_0001
+ */
+#define SUN4I_MSEL_SLEEP_MODE		(0x01 << 4) /* write in reset mode */
+#define SUN4I_MSEL_WAKE_UP		(0x00 << 4)
+#define SUN4I_MSEL_SINGLE_FILTER	(0x01 << 3) /* write in reset mode */
+#define SUN4I_MSEL_DUAL_FILTERS		(0x00 << 3)
+#define SUN4I_MSEL_LOOPBACK_MODE	BIT(2)
+#define SUN4I_MSEL_LISTEN_ONLY_MODE	BIT(1)
+#define SUN4I_MSEL_RESET_MODE		BIT(0)
+
+/* command register (w)
+ * offset:0x0004 default:0x0000_0000
+ */
+#define SUN4I_CMD_BUS_OFF_REQ	BIT(5)
+#define SUN4I_CMD_SELF_RCV_REQ	BIT(4)
+#define SUN4I_CMD_CLEAR_OR_FLAG	BIT(3)
+#define SUN4I_CMD_RELEASE_RBUF	BIT(2)
+#define SUN4I_CMD_ABORT_REQ	BIT(1)
+#define SUN4I_CMD_TRANS_REQ	BIT(0)
+
+/* status register (r)
+ * offset:0x0008 default:0x0000_003c
+ */
+#define SUN4I_STA_BIT_ERR	(0x00 << 22)
+#define SUN4I_STA_FORM_ERR	(0x01 << 22)
+#define SUN4I_STA_STUFF_ERR	(0x02 << 22)
+#define SUN4I_STA_OTHER_ERR	(0x03 << 22)
+#define SUN4I_STA_MASK_ERR	(0x03 << 22)
+#define SUN4I_STA_ERR_DIR	BIT(21)
+#define SUN4I_STA_ERR_SEG_CODE	(0x1f << 16)
+#define SUN4I_STA_START		(0x03 << 16)
+#define SUN4I_STA_ID28_21	(0x02 << 16)
+#define SUN4I_STA_ID20_18	(0x06 << 16)
+#define SUN4I_STA_SRTR		(0x04 << 16)
+#define SUN4I_STA_IDE		(0x05 << 16)
+#define SUN4I_STA_ID17_13	(0x07 << 16)
+#define SUN4I_STA_ID12_5	(0x0f << 16)
+#define SUN4I_STA_ID4_0		(0x0e << 16)
+#define SUN4I_STA_RTR		(0x0c << 16)
+#define SUN4I_STA_RB1		(0x0d << 16)
+#define SUN4I_STA_RB0		(0x09 << 16)
+#define SUN4I_STA_DLEN		(0x0b << 16)
+#define SUN4I_STA_DATA_FIELD	(0x0a << 16)
+#define SUN4I_STA_CRC_SEQUENCE	(0x08 << 16)
+#define SUN4I_STA_CRC_DELIMITER	(0x18 << 16)
+#define SUN4I_STA_ACK		(0x19 << 16)
+#define SUN4I_STA_ACK_DELIMITER	(0x1b << 16)
+#define SUN4I_STA_END		(0x1a << 16)
+#define SUN4I_STA_INTERMISSION	(0x12 << 16)
+#define SUN4I_STA_ACTIVE_ERROR	(0x11 << 16)
+#define SUN4I_STA_PASSIVE_ERROR	(0x16 << 16)
+#define SUN4I_STA_TOLERATE_DOMINANT_BITS	(0x13 << 16)
+#define SUN4I_STA_ERROR_DELIMITER	(0x17 << 16)
+#define SUN4I_STA_OVERLOAD	(0x1c << 16)
+#define SUN4I_STA_BUS_OFF	BIT(7)
+#define SUN4I_STA_ERR_STA	BIT(6)
+#define SUN4I_STA_TRANS_BUSY	BIT(5)
+#define SUN4I_STA_RCV_BUSY	BIT(4)
+#define SUN4I_STA_TRANS_OVER	BIT(3)
+#define SUN4I_STA_TBUF_RDY	BIT(2)
+#define SUN4I_STA_DATA_ORUN	BIT(1)
+#define SUN4I_STA_RBUF_RDY	BIT(0)
+
+/* interrupt register (r)
+ * offset:0x000c default:0x0000_0000
+ */
+#define SUN4I_INT_BUS_ERR	BIT(7)
+#define SUN4I_INT_ARB_LOST	BIT(6)
+#define SUN4I_INT_ERR_PASSIVE	BIT(5)
+#define SUN4I_INT_WAKEUP	BIT(4)
+#define SUN4I_INT_DATA_OR	BIT(3)
+#define SUN4I_INT_ERR_WRN	BIT(2)
+#define SUN4I_INT_TBUF_VLD	BIT(1)
+#define SUN4I_INT_RBUF_VLD	BIT(0)
+
+/* interrupt enable register (r/w)
+ * offset:0x0010 default:0x0000_0000
+ */
+#define SUN4I_INTEN_BERR	BIT(7)
+#define SUN4I_INTEN_ARB_LOST	BIT(6)
+#define SUN4I_INTEN_ERR_PASSIVE	BIT(5)
+#define SUN4I_INTEN_WAKEUP	BIT(4)
+#define SUN4I_INTEN_OR		BIT(3)
+#define SUN4I_INTEN_ERR_WRN	BIT(2)
+#define SUN4I_INTEN_TX		BIT(1)
+#define SUN4I_INTEN_RX		BIT(0)
+
+/* error code */
+#define SUN4I_ERR_INRCV		(0x1 << 5)
+#define SUN4I_ERR_INTRANS	(0x0 << 5)
+
+/* filter mode */
+#define SUN4I_FILTER_CLOSE	0
+#define SUN4I_SINGLE_FLTER_MODE	1
+#define SUN4I_DUAL_FILTER_MODE	2
+
+/* message buffer flags */
+#define SUN4I_MSG_EFF_FLAG	BIT(7)
+#define SUN4I_MSG_RTR_FLAG	BIT(6)
+
+/* max. number of interrupts handled in ISR */
+#define SUN4I_CAN_MAX_IRQ	20
+#define SUN4I_MODE_MAX_RETRIES	100
+
+struct sun4ican_priv {
+	struct can_priv can;
+	void __iomem *base;
+	struct clk *clk;
+	spinlock_t cmdreg_lock;	/* lock for concurrent cmd register writes */
+};
+
+static const struct can_bittiming_const sun4ican_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 = 64,
+	.brp_inc = 1,
+};
+
+static void sun4i_can_write_cmdreg(struct sun4ican_priv *priv, u8 val)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&priv->cmdreg_lock, flags);
+	writel(val, priv->base + SUN4I_REG_CMD_ADDR);
+	spin_unlock_irqrestore(&priv->cmdreg_lock, flags);
+}
+
+static int set_normal_mode(struct net_device *dev)
+{
+	struct sun4ican_priv *priv = netdev_priv(dev);
+	int retry = SUN4I_MODE_MAX_RETRIES;
+	u32 mod_reg_val = 0;
+
+	do {
+		mod_reg_val = readl(priv->base + SUN4I_REG_MSEL_ADDR);
+		mod_reg_val &= ~SUN4I_MSEL_RESET_MODE;
+		writel(mod_reg_val, priv->base + SUN4I_REG_MSEL_ADDR);
+	} while (retry-- && (mod_reg_val & SUN4I_MSEL_RESET_MODE));
+
+	if (readl(priv->base + SUN4I_REG_MSEL_ADDR) & SUN4I_MSEL_RESET_MODE) {
+		netdev_err(dev,
+			   "setting controller into normal mode failed!\n");
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+static int set_reset_mode(struct net_device *dev)
+{
+	struct sun4ican_priv *priv = netdev_priv(dev);
+	int retry = SUN4I_MODE_MAX_RETRIES;
+	u32 mod_reg_val = 0;
+
+	do {
+		mod_reg_val = readl(priv->base + SUN4I_REG_MSEL_ADDR);
+		mod_reg_val |= SUN4I_MSEL_RESET_MODE;
+		writel(mod_reg_val, priv->base + SUN4I_REG_MSEL_ADDR);
+	} while (retry-- && !(mod_reg_val & SUN4I_MSEL_RESET_MODE));
+
+	if (!(readl(priv->base + SUN4I_REG_MSEL_ADDR) &
+	      SUN4I_MSEL_RESET_MODE)) {
+		netdev_err(dev, "setting controller into reset mode failed!\n");
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+/* bittiming is called in reset_mode only */
+static int sun4ican_set_bittiming(struct net_device *dev)
+{
+	struct sun4ican_priv *priv = netdev_priv(dev);
+	struct can_bittiming *bt = &priv->can.bittiming;
+	u32 cfg;
+
+	cfg = ((bt->brp - 1) & 0x3FF) |
+	     (((bt->sjw - 1) & 0x3) << 14) |
+	     (((bt->prop_seg + bt->phase_seg1 - 1) & 0xf) << 16) |
+	     (((bt->phase_seg2 - 1) & 0x7) << 20);
+	if (priv->can.ctrlmode & CAN_CTRLMODE_3_SAMPLES)
+		cfg |= 0x800000;
+
+	netdev_dbg(dev, "setting BITTIMING=0x%08x\n", cfg);
+	writel(cfg, priv->base + SUN4I_REG_BTIME_ADDR);
+
+	return 0;
+}
+
+static int sun4ican_get_berr_counter(const struct net_device *dev,
+				     struct can_berr_counter *bec)
+{
+	struct sun4ican_priv *priv = netdev_priv(dev);
+	u32 errors;
+	int err;
+
+	err = clk_prepare_enable(priv->clk);
+	if (err) {
+		netdev_err(dev, "could not enable clock\n");
+		return err;
+	}
+
+	errors = readl(priv->base + SUN4I_REG_ERRC_ADDR);
+
+	bec->txerr = errors & 0xFF;
+	bec->rxerr = (errors >> 16) & 0xFF;
+
+	clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+
+static int sun4i_can_start(struct net_device *dev)
+{
+	struct sun4ican_priv *priv = netdev_priv(dev);
+	int err;
+	u32 mod_reg_val;
+
+	/* we need to enter the reset mode */
+	err = set_reset_mode(dev);
+	if (err) {
+		netdev_err(dev, "could not enter reset mode\n");
+		return err;
+	}
+
+	/* set filters - we accept all */
+	writel(0x00000000, priv->base + SUN4I_REG_ACPC_ADDR);
+	writel(0xFFFFFFFF, priv->base + SUN4I_REG_ACPM_ADDR);
+
+	/* clear error counters and error code capture */
+	writel(0, priv->base + SUN4I_REG_ERRC_ADDR);
+
+	/* enable interrupts */
+	if (priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)
+		writel(0xFF, priv->base + SUN4I_REG_INTEN_ADDR);
+	else
+		writel(0xFF & ~SUN4I_INTEN_BERR,
+		       priv->base + SUN4I_REG_INTEN_ADDR);
+
+	/* enter the selected mode */
+	mod_reg_val = readl(priv->base + SUN4I_REG_MSEL_ADDR);
+	if (priv->can.ctrlmode & CAN_CTRLMODE_PRESUME_ACK)
+		mod_reg_val |= SUN4I_MSEL_LOOPBACK_MODE;
+	else if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
+		mod_reg_val |= SUN4I_MSEL_LISTEN_ONLY_MODE;
+	writel(mod_reg_val, priv->base + SUN4I_REG_MSEL_ADDR);
+
+	err = sun4ican_set_bittiming(dev);
+	if (err)
+		return err;
+
+	/* we are ready to enter the normal mode */
+	err = set_normal_mode(dev);
+	if (err) {
+		netdev_err(dev, "could not enter normal mode\n");
+		return err;
+	}
+
+	priv->can.state = CAN_STATE_ERROR_ACTIVE;
+
+	return 0;
+}
+
+static int sun4i_can_stop(struct net_device *dev)
+{
+	struct sun4ican_priv *priv = netdev_priv(dev);
+	int err;
+
+	priv->can.state = CAN_STATE_STOPPED;
+	/* we need to enter reset mode */
+	err = set_reset_mode(dev);
+	if (err) {
+		netdev_err(dev, "could not enter reset mode\n");
+		return err;
+	}
+
+	/* disable all interrupts */
+	writel(0, priv->base + SUN4I_REG_INTEN_ADDR);
+
+	return 0;
+}
+
+static int sun4ican_set_mode(struct net_device *dev, enum can_mode mode)
+{
+	int err;
+
+	switch (mode) {
+	case CAN_MODE_START:
+		err = sun4i_can_start(dev);
+		if (err) {
+			netdev_err(dev, "starting CAN controller failed!\n");
+			return err;
+		}
+		if (netif_queue_stopped(dev))
+			netif_wake_queue(dev);
+		break;
+
+	default:
+		return -EOPNOTSUPP;
+	}
+	return 0;
+}
+
+/* transmit a CAN message
+ * message layout in the sk_buff should be like this:
+ * xx xx xx xx         ff         ll 00 11 22 33 44 55 66 77
+ * [ can_id ] [flags] [len] [can data (up to 8 bytes]
+ */
+static int sun4ican_start_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct sun4ican_priv *priv = netdev_priv(dev);
+	struct can_frame *cf = (struct can_frame *)skb->data;
+	u8 dlc;
+	u32 dreg, msg_flag_n;
+	canid_t id;
+	int i;
+
+	if (can_dropped_invalid_skb(dev, skb))
+		return NETDEV_TX_OK;
+
+	netif_stop_queue(dev);
+
+	id = cf->can_id;
+	dlc = cf->can_dlc;
+	msg_flag_n = dlc;
+
+	if (id & CAN_RTR_FLAG)
+		msg_flag_n |= SUN4I_MSG_RTR_FLAG;
+
+	if (id & CAN_EFF_FLAG) {
+		msg_flag_n |= SUN4I_MSG_EFF_FLAG;
+		dreg = SUN4I_REG_BUF5_ADDR;
+		writel((id >> 21) & 0xFF, priv->base + SUN4I_REG_BUF1_ADDR);
+		writel((id >> 13) & 0xFF, priv->base + SUN4I_REG_BUF2_ADDR);
+		writel((id >> 5)  & 0xFF, priv->base + SUN4I_REG_BUF3_ADDR);
+		writel((id << 3)  & 0xF8, priv->base + SUN4I_REG_BUF4_ADDR);
+	} else {
+		dreg = SUN4I_REG_BUF3_ADDR;
+		writel((id >> 3) & 0xFF, priv->base + SUN4I_REG_BUF1_ADDR);
+		writel((id << 5) & 0xE0, priv->base + SUN4I_REG_BUF2_ADDR);
+	}
+
+	for (i = 0; i < dlc; i++)
+		writel(cf->data[i], priv->base + (dreg + i * 4));
+
+	writel(msg_flag_n, priv->base + SUN4I_REG_BUF0_ADDR);
+
+	can_put_echo_skb(skb, dev, 0);
+
+	if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
+		sun4i_can_write_cmdreg(priv, SUN4I_CMD_SELF_RCV_REQ);
+	else
+		sun4i_can_write_cmdreg(priv, SUN4I_CMD_TRANS_REQ);
+
+	return NETDEV_TX_OK;
+}
+
+static void sun4i_can_rx(struct net_device *dev)
+{
+	struct sun4ican_priv *priv = netdev_priv(dev);
+	struct net_device_stats *stats = &dev->stats;
+	struct can_frame *cf;
+	struct sk_buff *skb;
+	u8 fi;
+	u32 dreg;
+	canid_t id;
+	int i;
+
+	/* create zero'ed CAN frame buffer */
+	skb = alloc_can_skb(dev, &cf);
+	if (!skb)
+		return;
+
+	fi = readl(priv->base + SUN4I_REG_BUF0_ADDR);
+	cf->can_dlc = get_can_dlc(fi & 0x0F);
+	if (fi & SUN4I_MSG_EFF_FLAG) {
+		dreg = SUN4I_REG_BUF5_ADDR;
+		id = (readl(priv->base + SUN4I_REG_BUF1_ADDR) << 21) |
+		     (readl(priv->base + SUN4I_REG_BUF2_ADDR) << 13) |
+		     (readl(priv->base + SUN4I_REG_BUF3_ADDR) << 5)  |
+		    ((readl(priv->base + SUN4I_REG_BUF4_ADDR) >> 3)  & 0x1f);
+		id |= CAN_EFF_FLAG;
+	} else {
+		dreg = SUN4I_REG_BUF3_ADDR;
+		id = (readl(priv->base + SUN4I_REG_BUF1_ADDR) << 3) |
+		    ((readl(priv->base + SUN4I_REG_BUF2_ADDR) >> 5) & 0x7);
+	}
+
+	/* remote frame ? */
+	if (fi & SUN4I_MSG_RTR_FLAG)
+		id |= CAN_RTR_FLAG;
+	else
+		for (i = 0; i < cf->can_dlc; i++)
+			cf->data[i] = readl(priv->base + dreg + i * 4);
+
+	cf->can_id = id;
+
+	sun4i_can_write_cmdreg(priv, SUN4I_CMD_RELEASE_RBUF);
+
+	stats->rx_packets++;
+	stats->rx_bytes += cf->can_dlc;
+	netif_rx(skb);
+
+	can_led_event(dev, CAN_LED_EVENT_RX);
+}
+
+static int sun4i_can_err(struct net_device *dev, u8 isrc, u8 status)
+{
+	struct sun4ican_priv *priv = netdev_priv(dev);
+	struct net_device_stats *stats = &dev->stats;
+	struct can_frame *cf;
+	struct sk_buff *skb;
+	enum can_state state = priv->can.state;
+	enum can_state rx_state, tx_state;
+	unsigned int rxerr, txerr, errc;
+	u32 ecc, alc;
+
+	/* we don't skip if alloc fails because we want the stats anyhow */
+	skb = alloc_can_err_skb(dev, &cf);
+
+	errc = readl(priv->base + SUN4I_REG_ERRC_ADDR);
+	rxerr = (errc >> 16) & 0xFF;
+	txerr = errc & 0xFF;
+
+	if (skb) {
+		cf->data[6] = txerr;
+		cf->data[7] = rxerr;
+	}
+
+	if (isrc & SUN4I_INT_DATA_OR) {
+		/* data overrun interrupt */
+		netdev_dbg(dev, "data overrun interrupt\n");
+		if (likely(skb)) {
+			cf->can_id |= CAN_ERR_CRTL;
+			cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
+		}
+		stats->rx_over_errors++;
+		stats->rx_errors++;
+		/* clear bit */
+		sun4i_can_write_cmdreg(priv, SUN4I_CMD_CLEAR_OR_FLAG);
+	}
+	if (isrc & SUN4I_INT_ERR_WRN) {
+		/* error warning interrupt */
+		netdev_dbg(dev, "error warning interrupt\n");
+
+		if (status & SUN4I_STA_BUS_OFF)
+			state = CAN_STATE_BUS_OFF;
+		else if (status & SUN4I_STA_ERR_STA)
+			state = CAN_STATE_ERROR_WARNING;
+		else
+			state = CAN_STATE_ERROR_ACTIVE;
+	}
+	if (isrc & SUN4I_INT_BUS_ERR) {
+		/* bus error interrupt */
+		netdev_dbg(dev, "bus error interrupt\n");
+		priv->can.can_stats.bus_error++;
+		stats->rx_errors++;
+
+		if (likely(skb)) {
+			ecc = readl(priv->base + SUN4I_REG_STA_ADDR);
+
+			cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
+
+			switch (ecc & SUN4I_STA_MASK_ERR) {
+			case SUN4I_STA_BIT_ERR:
+				cf->data[2] |= CAN_ERR_PROT_BIT;
+				break;
+			case SUN4I_STA_FORM_ERR:
+				cf->data[2] |= CAN_ERR_PROT_FORM;
+				break;
+			case SUN4I_STA_STUFF_ERR:
+				cf->data[2] |= CAN_ERR_PROT_STUFF;
+				break;
+			default:
+				cf->data[2] |= CAN_ERR_PROT_UNSPEC;
+				cf->data[3] = (ecc & SUN4I_STA_ERR_SEG_CODE)
+					       >> 16;
+				break;
+			}
+			/* error occurred during transmission? */
+			if ((ecc & SUN4I_STA_ERR_DIR) == 0)
+				cf->data[2] |= CAN_ERR_PROT_TX;
+		}
+	}
+	if (isrc & SUN4I_INT_ERR_PASSIVE) {
+		/* error passive interrupt */
+		netdev_dbg(dev, "error passive interrupt\n");
+		if (state == CAN_STATE_ERROR_PASSIVE)
+			state = CAN_STATE_ERROR_WARNING;
+		else
+			state = CAN_STATE_ERROR_PASSIVE;
+	}
+	if (isrc & SUN4I_INT_ARB_LOST) {
+		/* arbitration lost interrupt */
+		netdev_dbg(dev, "arbitration lost interrupt\n");
+		alc = readl(priv->base + SUN4I_REG_STA_ADDR);
+		priv->can.can_stats.arbitration_lost++;
+		stats->tx_errors++;
+		if (likely(skb)) {
+			cf->can_id |= CAN_ERR_LOSTARB;
+			cf->data[0] = (alc & 0x1f) >> 8;
+		}
+	}
+
+	if (state != priv->can.state) {
+		tx_state = txerr >= rxerr ? state : 0;
+		rx_state = txerr <= rxerr ? state : 0;
+
+		if (likely(skb))
+			can_change_state(dev, cf, tx_state, rx_state);
+		else
+			priv->can.state = state;
+		if (state == CAN_STATE_BUS_OFF)
+			can_bus_off(dev);
+	}
+
+	if (likely(skb)) {
+		stats->rx_packets++;
+		stats->rx_bytes += cf->can_dlc;
+		netif_rx(skb);
+	} else {
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static irqreturn_t sun4i_can_interrupt(int irq, void *dev_id)
+{
+	struct net_device *dev = (struct net_device *)dev_id;
+	struct sun4ican_priv *priv = netdev_priv(dev);
+	struct net_device_stats *stats = &dev->stats;
+	u8 isrc, status;
+	int n = 0;
+
+	while ((isrc = readl(priv->base + SUN4I_REG_INT_ADDR)) &&
+	       (n < SUN4I_CAN_MAX_IRQ)) {
+		n++;
+		status = readl(priv->base + SUN4I_REG_STA_ADDR);
+
+		if (isrc & SUN4I_INT_WAKEUP)
+			netdev_warn(dev, "wakeup interrupt\n");
+
+		if (isrc & SUN4I_INT_TBUF_VLD) {
+			/* transmission complete interrupt */
+			stats->tx_bytes +=
+			    readl(priv->base +
+				  SUN4I_REG_RBUF_RBACK_START_ADDR) & 0xf;
+			stats->tx_packets++;
+			can_get_echo_skb(dev, 0);
+			netif_wake_queue(dev);
+			can_led_event(dev, CAN_LED_EVENT_TX);
+		}
+		if (isrc & SUN4I_INT_RBUF_VLD) {
+			/* receive interrupt */
+			while (status & SUN4I_STA_RBUF_RDY) {
+				/* RX buffer is not empty */
+				sun4i_can_rx(dev);
+				status = readl(priv->base + SUN4I_REG_STA_ADDR);
+			}
+		}
+		if (isrc &
+		    (SUN4I_INT_DATA_OR | SUN4I_INT_ERR_WRN | SUN4I_INT_BUS_ERR |
+		     SUN4I_INT_ERR_PASSIVE | SUN4I_INT_ARB_LOST)) {
+			/* error interrupt */
+			if (sun4i_can_err(dev, isrc, status))
+				netdev_err(dev, "can't allocate buffer - clearing pending interrupts\n");
+		}
+		/* clear interrupts */
+		writel(isrc, priv->base + SUN4I_REG_INT_ADDR);
+		readl(priv->base + SUN4I_REG_INT_ADDR);
+	}
+	if (n >= SUN4I_CAN_MAX_IRQ)
+		netdev_dbg(dev, "%d messages handled in ISR", n);
+
+	return (n) ? IRQ_HANDLED : IRQ_NONE;
+}
+
+static int sun4ican_open(struct net_device *dev)
+{
+	struct sun4ican_priv *priv = netdev_priv(dev);
+	int err;
+
+	/* common open */
+	err = open_candev(dev);
+	if (err)
+		return err;
+
+	/* register interrupt handler */
+	err = request_irq(dev->irq, sun4i_can_interrupt, 0, dev->name, dev);
+	if (err) {
+		netdev_err(dev, "request_irq err: %d\n", err);
+		goto exit_irq;
+	}
+
+	/* turn on clocking for CAN peripheral block */
+	err = clk_prepare_enable(priv->clk);
+	if (err) {
+		netdev_err(dev, "could not enable CAN peripheral clock\n");
+		goto exit_clock;
+	}
+
+	err = sun4i_can_start(dev);
+	if (err) {
+		netdev_err(dev, "could not start CAN peripheral\n");
+		goto exit_can_start;
+	}
+
+	can_led_event(dev, CAN_LED_EVENT_OPEN);
+	netif_start_queue(dev);
+
+	return 0;
+
+exit_can_start:
+	clk_disable_unprepare(priv->clk);
+exit_clock:
+	free_irq(dev->irq, dev);
+exit_irq:
+	close_candev(dev);
+	return err;
+}
+
+static int sun4ican_close(struct net_device *dev)
+{
+	struct sun4ican_priv *priv = netdev_priv(dev);
+
+	netif_stop_queue(dev);
+	sun4i_can_stop(dev);
+	clk_disable_unprepare(priv->clk);
+
+	free_irq(dev->irq, dev);
+	close_candev(dev);
+	can_led_event(dev, CAN_LED_EVENT_STOP);
+
+	return 0;
+}
+
+static const struct net_device_ops sun4ican_netdev_ops = {
+	.ndo_open = sun4ican_open,
+	.ndo_stop = sun4ican_close,
+	.ndo_start_xmit = sun4ican_start_xmit,
+};
+
+static const struct of_device_id sun4ican_of_match[] = {
+	{.compatible = "allwinner,sun4i-a10-can"},
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, sun4ican_of_match);
+
+static int sun4ican_remove(struct platform_device *pdev)
+{
+	struct net_device *dev = platform_get_drvdata(pdev);
+
+	unregister_netdev(dev);
+	free_candev(dev);
+
+	return 0;
+}
+
+static int sun4ican_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct resource *mem;
+	struct clk *clk;
+	void __iomem *addr;
+	int err, irq;
+	struct net_device *dev;
+	struct sun4ican_priv *priv;
+
+	clk = of_clk_get(np, 0);
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "unable to request clock\n");
+		err = -ENODEV;
+		goto exit;
+	}
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "could not get a valid irq\n");
+		err = -ENODEV;
+		goto exit;
+	}
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	addr = devm_ioremap_resource(&pdev->dev, mem);
+	if (IS_ERR(addr)) {
+		err = -EBUSY;
+		goto exit;
+	}
+
+	dev = alloc_candev(sizeof(struct sun4ican_priv), 1);
+	if (!dev) {
+		dev_err(&pdev->dev,
+			"could not allocate memory for CAN device\n");
+		err = -ENOMEM;
+		goto exit;
+	}
+
+	dev->netdev_ops = &sun4ican_netdev_ops;
+	dev->irq = irq;
+	dev->flags |= IFF_ECHO;
+
+	priv = netdev_priv(dev);
+	priv->can.clock.freq = clk_get_rate(clk);
+	priv->can.bittiming_const = &sun4ican_bittiming_const;
+	priv->can.do_set_mode = sun4ican_set_mode;
+	priv->can.do_get_berr_counter = sun4ican_get_berr_counter;
+	priv->can.ctrlmode_supported = CAN_CTRLMODE_BERR_REPORTING |
+				       CAN_CTRLMODE_LISTENONLY |
+				       CAN_CTRLMODE_LOOPBACK |
+				       CAN_CTRLMODE_PRESUME_ACK |
+				       CAN_CTRLMODE_3_SAMPLES;
+	priv->base = addr;
+	priv->clk = clk;
+	spin_lock_init(&priv->cmdreg_lock);
+
+	platform_set_drvdata(pdev, dev);
+	SET_NETDEV_DEV(dev, &pdev->dev);
+
+	err = register_candev(dev);
+	if (err) {
+		dev_err(&pdev->dev, "registering %s failed (err=%d)\n",
+			DRV_NAME, err);
+		goto exit_free;
+	}
+	devm_can_led_init(dev);
+
+	dev_info(&pdev->dev, "device registered (base=%p, irq=%d)\n",
+		 priv->base, dev->irq);
+
+	return 0;
+
+exit_free:
+	free_candev(dev);
+exit:
+	return err;
+}
+
+static struct platform_driver sun4i_can_driver = {
+	.driver = {
+		.name = DRV_NAME,
+		.of_match_table = sun4ican_of_match,
+	},
+	.probe = sun4ican_probe,
+	.remove = sun4ican_remove,
+};
+
+module_platform_driver(sun4i_can_driver);
+
+MODULE_AUTHOR("Peter Chen <xingkongcp@gmail.com>");
+MODULE_AUTHOR("Gerhard Bertelsmann <info@gerhard-bertelsmann.de>");
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_DESCRIPTION(DRV_NAME "CAN driver for Allwinner SoCs (A10/A20)");