Subject: Re: [PATCH 1/3] can: m_can: add Bosch M_CAN controller support

From: Marc Kleine-Budde <[email-masked]>
Date: Tue, 01 Jul 2014 12:29:17 +0200

On 06/27/2014 12:00 PM, Dong Aisheng wrote:
> The patch adds the basic CAN TX/RX function support for Bosch M_CAN controller.
> For TX, only one dedicated tx buffer is used for sending data.
> For RX, RXFIFO 0 is used for receiving data to avoid overflow.
> Rx FIFO 1 and Rx Buffers are not used currently, as well as Tx Event FIFO.
> 
> Due to the message ram can be shared by multi m_can instances
> and the fifo element is configurable which is SoC dependant,
> the design is to parse the message ram related configuration data from device
> tree rather than hardcode define it in driver which can make the message
> ram sharing fully transparent to M_CAN controller driver,
> then we can gain better driver maintainability and future features upgrade.
> 
> M_CAN also supports CANFD protocol features like data payload up to 64 bytes
> and bitrate switch at runtime, however, this patch still does not add the
> support for these features.
> 
> Signed-off-by: Dong Aisheng <[email-masked]>
> ---
>  .../devicetree/bindings/net/can/m_can.txt          |   29 +
>  drivers/net/can/Kconfig                            |    5 +
>  drivers/net/can/Makefile                           |    1 +
>  drivers/net/can/m_can.c                            |  867 ++++++++++++++++++++
>  4 files changed, 902 insertions(+), 0 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/net/can/m_can.txt b/Documentation/devicetree/bindings/net/can/m_can.txt
> new file mode 100644
> index 0000000..2b22d02
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/net/can/m_can.txt
> @@ -0,0 +1,29 @@
> +Bosch MCAN controller Device Tree Bindings
> +-------------------------------------------------
> +
> +Required properties:
> +- compatible		: Should be "bosch,m_can" for M_CAN controllers
> +- reg			: physical base address and size of the M_CAN
> +			  registers map and message ram
> +- interrupts		: property with a value describing the interrupt
> +			  number
> +- clocks		: clocks used by controller
> +- mram-cfg		: message ram configuration data, the format is
> +  <offset sidf_elems xidf_elems rxf1_elems rxb_elems txe_elems txb_elems>
> +  The 'offset' is the address offset inside the message ram. This is usually set
> +  if you're using the shared message ram while the other part is used by another
> +  m_can controller.
> +  The left cell are all the number of each elements inside the message ram.
> +  Please refer to 2.4.1 Message RAM Con.guration in Bosch M_CAN user mannual
> +  for each elements definition.
> +
> +Example:
> +canfd1: canfd@020e8000 {
> +	compatible = "bosch,m_can";
> +	reg = <0x020e8000 0x4000>, <0x02298000 0x4000>;
> +	reg-names = "canfd", "message_ram";
> +	interrupts = <0 114 0x04>;
> +	clocks = <&clks IMX6SX_CLK_CANFD>;
> +	mram-cfg = <0x0 0 0 32 32 32 0 1>;
> +	status = "disabled";
> +};
> diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
> index 4168822..3fd1c4a 100644
> --- a/drivers/net/can/Kconfig
> +++ b/drivers/net/can/Kconfig
> @@ -137,6 +137,11 @@ config CAN_XILINXCAN
>  	  Xilinx CAN driver. This driver supports both soft AXI CAN IP and
>  	  Zynq CANPS IP.
>  
> +config CAN_M_CAN
> +	tristate "Bosch M_CAN devices"
> +	---help---
> +	  Say Y here if you want to support for Bosch M_CAN controller.
> +
>  source "drivers/net/can/mscan/Kconfig"
>  
>  source "drivers/net/can/sja1000/Kconfig"
> diff --git a/drivers/net/can/Makefile b/drivers/net/can/Makefile
> index 1697f22..69dee2c 100644
> --- a/drivers/net/can/Makefile
> +++ b/drivers/net/can/Makefile
> @@ -17,6 +17,7 @@ obj-y				+= softing/
>  obj-$(CONFIG_CAN_SJA1000)	+= sja1000/
>  obj-$(CONFIG_CAN_MSCAN)		+= mscan/
>  obj-$(CONFIG_CAN_C_CAN)		+= c_can/
> +obj-$(CONFIG_CAN_M_CAN)		+= m_can.o
>  obj-$(CONFIG_CAN_CC770)		+= cc770/
>  obj-$(CONFIG_CAN_AT91)		+= at91_can.o
>  obj-$(CONFIG_CAN_TI_HECC)	+= ti_hecc.o
> diff --git a/drivers/net/can/m_can.c b/drivers/net/can/m_can.c
> new file mode 100644
> index 0000000..61e9a8e
> --- /dev/null
> +++ b/drivers/net/can/m_can.c
> @@ -0,0 +1,867 @@
> +/*
> + * CAN bus driver for Bosch M_CAN controller
> + *
> + * Copyright (C) 2014 Freescale Semiconductor, Inc.
> + *	Dong Aisheng <[email-masked]>
> + *
> + * Bosch M_CAN user manual can be obtained from:
> + * http://www.bosch-semiconductors.de/media/pdf_1/ipmodules_1/m_can/
> + * mcan_users_manual_v302.pdf
> + *
> + * This file is licensed under the terms of the GNU General Public
> + * License version 2. This program is licensed "as is" without any
> + * warranty of any kind, whether express or implied.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/if_arp.h>
> +#include <linux/if_ether.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/list.h>
> +#include <linux/module.h>
> +#include <linux/netdevice.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/pinctrl/consumer.h>
> +#include <linux/platform_device.h>
> +
> +#include <linux/can/dev.h>
> +
> +/* napi related */
> +#define M_CAN_NAPI_WEIGHT	64
> +
> +/* registers definition */
> +enum m_can_reg {
> +	M_CAN_CREL	= 0x0,
> +	M_CAN_ENDN	= 0x4,
> +	M_CAN_CUST	= 0x8,
> +	M_CAN_FBTP	= 0xc,
> +	M_CAN_TEST	= 0x10,
> +	M_CAN_RWD	= 0x14,
> +	M_CAN_CCCR	= 0x18,
> +	M_CAN_BTP	= 0x1c,
> +	M_CAN_TSCC	= 0x20,
> +	M_CAN_TSCV	= 0x24,
> +	M_CAN_TOCC	= 0x28,
> +	M_CAN_TOCV	= 0x2c,
> +	M_CAN_ECR	= 0x40,
> +	M_CAN_PSR	= 0x44,
> +	M_CAN_IR	= 0x50,
> +	M_CAN_IE	= 0x54,
> +	M_CAN_ILS	= 0x58,
> +	M_CAN_ILE	= 0x5c,
> +	M_CAN_GFC	= 0x80,
> +	M_CAN_SIDFC	= 0x84,
> +	M_CAN_XIDFC	= 0x88,
> +	M_CAN_XIDAM	= 0x90,
> +	M_CAN_HPMS	= 0x94,
> +	M_CAN_NDAT1	= 0x98,
> +	M_CAN_NDAT2	= 0x9c,
> +	M_CAN_RXF0C	= 0xa0,
> +	M_CAN_RXF0S	= 0xa4,
> +	M_CAN_RXF0A	= 0xa8,
> +	M_CAN_RXBC	= 0xac,
> +	M_CAN_RXF1C	= 0xb0,
> +	M_CAN_RXF1S	= 0xb4,
> +	M_CAN_RXF1A	= 0xb8,
> +	M_CAN_RXESC	= 0xbc,
> +	M_CAN_TXBC	= 0xc0,
> +	M_CAN_TXFQS	= 0xc4,
> +	M_CAN_TXESC	= 0xc8,
> +	M_CAN_TXBRP	= 0xcc,
> +	M_CAN_TXBAR	= 0xd0,
> +	M_CAN_TXBCR	= 0xd4,
> +	M_CAN_TXBTO	= 0xd8,
> +	M_CAN_TXBCF	= 0xdc,
> +	M_CAN_TXBTIE	= 0xe0,
> +	M_CAN_TXBCIE	= 0xe4,
> +	M_CAN_TXEFC	= 0xf0,
> +	M_CAN_TXEFS	= 0xf4,
> +	M_CAN_TXEFA	= 0xf8,
> +};
> +
> +/* CC Control Register(CCCR) */
> +#define CCCR_CCE	BIT(1)
> +#define CCCR_INIT	BIT(0)
> +
> +/* Bit Timing & Prescaler Register (BTP) */
> +#define BTR_BRP_MASK		0x3ff
> +#define BTR_BRP_SHIFT		16
> +#define BTR_TSEG1_SHIFT		8
> +#define BTR_TSEG1_MASK		(0x3f << BTR_TSEG1_SHIFT)
> +#define BTR_TSEG2_SHIFT		4
> +#define BTR_TSEG2_MASK		(0xf << BTR_TSEG2_SHIFT)
> +#define BTR_SJW_SHIFT		0
> +#define BTR_SJW_MASK		0xf
> +
> +/* Interrupt Register(IR) */
> +#define IR_ALL_INT	0xffffffff
> +#define IR_STE		BIT(31)
> +#define IR_FOE		BIT(30)
> +#define IR_ACKE		BIT(29)
> +#define IR_BE		BIT(28)
> +#define IR_CRCE		BIT(27)
> +#define IR_WDI		BIT(26)
> +#define IR_BO		BIT(25)
> +#define IR_EW		BIT(24)
> +#define IR_EP		BIT(23)
> +#define IR_ELO		BIT(22)
> +#define IR_BEU		BIT(21)
> +#define IR_BEC		BIT(20)
> +#define IR_DRX		BIT(19)
> +#define IR_TOO		BIT(18)
> +#define IR_MRAF		BIT(17)
> +#define IR_TSW		BIT(16)
> +#define IR_TEFL		BIT(15)
> +#define IR_TEFF		BIT(14)
> +#define IR_TEFW		BIT(13)
> +#define IR_TEFN		BIT(12)
> +#define IR_TFE		BIT(11)
> +#define IR_TCF		BIT(10)
> +#define IR_TC		BIT(9)
> +#define IR_HPM		BIT(8)
> +#define IR_RF1L		BIT(7)
> +#define IR_RF1F		BIT(6)
> +#define IR_RF1W		BIT(5)
> +#define IR_RF1N		BIT(4)
> +#define IR_RF0L		BIT(3)
> +#define IR_RF0F		BIT(2)
> +#define IR_RF0W		BIT(1)
> +#define IR_RF0N		BIT(0)
> +#define IR_ERR_ALL	(IR_STE	| IR_FOE | IR_ACKE | IR_BE | IR_CRCE | \
> +		IR_WDI | IR_BO | IR_EW | IR_EP | IR_ELO | IR_BEU | \
> +		IR_BEC | IR_TOO | IR_MRAF | IR_TSW | IR_TEFL | IR_RF1L | \
> +		IR_RF0L)
> +
> +/* Rx FIFO 0/1 Configuration (RXF0C/RXF1C) */
> +#define RXFC_FWM_OFF	24
> +#define RXFC_FWM_MASK	0x7f
> +#define RXFC_FWM_1	(1 << RXFC_FWM_OFF)
> +#define RXFC_FS_OFF	16
> +#define RXFC_FS_MASK	0x7f
> +
> +/* Rx FIFO 0/1 Status (RXF0S/RXF1S) */
> +#define RXFS_RFL	BIT(25)
> +#define RXFS_FF		BIT(24)
> +#define RXFS_FPI_OFF	16
> +#define RXFS_FPI_MASK	0x3f0000
> +#define RXFS_FGI_OFF	8
> +#define RXFS_FGI_MASK	0x3f00
> +#define RXFS_FFL_MASK	0x7f
> +
> +/* Tx Buffer Configuration(TXBC) */
> +#define TXBC_NDTB_OFF	16
> +#define TXBC_NDTB_MASK	0x3f
> +
> +/* Tx Buffer Element Size Configuration(TXESC) */
> +#define TXESC_TBDS_8BYTES	0x0
> +/* Tx Buffer Element */
> +#define TX_BUF_XTD	BIT(30)
> +#define TX_BUF_RTR	BIT(29)
> +
> +/* Rx Buffer Element Size Configuration(TXESC) */
> +#define M_CAN_RXESC_8BYTES	0x0
> +/* Tx Buffer Element */
> +#define RX_BUF_ESI	BIT(31)
> +#define RX_BUF_XTD	BIT(30)
> +#define RX_BUF_RTR	BIT(29)
> +
> +/* Message RAM Configuration (in bytes) */
> +#define SIDF_ELEMENT_SIZE	4
> +#define XIDF_ELEMENT_SIZE	8
> +#define RXF0_ELEMENT_SIZE	16
> +#define RXF1_ELEMENT_SIZE	16
> +#define RXB_ELEMENT_SIZE	16
> +#define TXE_ELEMENT_SIZE	8
> +#define TXB_ELEMENT_SIZE	16
> +
> +/* m_can private data structure */
> +struct m_can_priv {
> +	struct can_priv can;	/* must be the first member */
> +	struct napi_struct napi;
> +	struct net_device *dev;
> +	struct device *device;
> +	struct clk *clk;
> +	void __iomem *base;
> +	u32 irqstatus;
> +
> +	/* message ram configuration */
> +	void __iomem *mram_base;
> +	u32 mram_off;
> +	u32 sidf_elems;
> +	u32 sidf_off;
> +	u32 xidf_elems;
> +	u32 xidf_off;
> +	u32 rxf0_elems;
> +	u32 rxf0_off;
> +	u32 rxf1_elems;
> +	u32 rxf1_off;
> +	u32 rxb_elems;
> +	u32 rxb_off;
> +	u32 txe_elems;
> +	u32 txe_off;
> +	u32 txb_elems;
> +	u32 txb_off;
> +};
> +
> +static inline u32 m_can_read(const struct m_can_priv *priv, enum m_can_reg reg)
> +{
> +	return readl(priv->base + reg);
> +}
> +
> +static inline void m_can_write(const struct m_can_priv *priv,
> +				enum m_can_reg reg, u32 val)
> +{
> +	writel(val, priv->base + reg);
> +}
> +
> +static inline void m_can_config_endisable(const struct m_can_priv *priv,
> +				bool enable)
> +{
> +	u32 cccr = m_can_read(priv, M_CAN_CCCR);
> +	u32 timeout = 10, val;
> +
> +	if (enable) {
> +		/* enable m_can configuration */
> +		m_can_write(priv, M_CAN_CCCR, cccr | CCCR_INIT);
> +		/* CCCR.CCE can only be set/reset while CCCR.INIT = '1' */
> +		m_can_write(priv, M_CAN_CCCR, cccr | CCCR_INIT | CCCR_CCE);
> +	} else {
> +		m_can_write(priv, M_CAN_CCCR, cccr & ~(CCCR_INIT | CCCR_CCE));
> +	}
> +
> +	/* there's a delay for module initialization */
> +	val = enable ? CCCR_INIT | CCCR_CCE : 0;

nitpick:

If you declare:

    u32 val = 0;

you can use a more readable:

    if (enable)
    	val = CCCR_INIT | CCCR_CCE;

> +	while ((m_can_read(priv, M_CAN_CCCR) & (CCCR_INIT | CCCR_CCE))
> +				!= val) {
> +		if (timeout == 0) {
> +			netdev_warn(priv->dev, "Failed to init module\n");
> +			return;
> +		}
> +		timeout--;
> +		udelay(1);
> +	}
> +}
> +
> +static void m_can_enable_all_interrupts(struct m_can_priv *priv, bool enable)
> +{
> +	m_can_write(priv, M_CAN_ILE, enable ? 0x00000003 : 0x0);
> +}

Can you make this two functions, I personally don't like to call a
function: *_enable_* if is actually disabled something. Please make use
of the defines instead of using 0x3.

> +
> +static int m_can_do_rx_poll(struct net_device *dev, int quota)
> +{
> +	struct m_can_priv *priv = netdev_priv(dev);
> +	struct net_device_stats *stats = &dev->stats;
> +	struct sk_buff *skb;
> +	struct can_frame *frame;
> +	u32 rxfs, flags, fgi;
> +	u32 num_rx_pkts = 0;
> +
> +	rxfs = m_can_read(priv, M_CAN_RXF0S);
> +	if (!(rxfs & RXFS_FFL_MASK)) {
> +		netdev_dbg(dev, "no messages in fifo0\n");
> +		return 0;
> +	}
> +
> +	while ((rxfs & RXFS_FFL_MASK) && (quota > 0)) {
> +		netdev_dbg(dev, "fifo0 status 0x%x\n", rxfs);

Please remove the netdev_dbg(), once the driver is stable it should be
of no use.

> +		if (rxfs & RXFS_RFL)
> +			netdev_warn(dev, "Rx FIFO 0 Message Lost\n");

What does that mean? Can you still rx the message if it's lost?

> +
> +		skb = alloc_can_skb(dev, &frame);
> +		if (!skb) {
> +			stats->rx_dropped++;
> +			return -ENOMEM;

Have a look at the user of m_can_do_rx_poll() and how it makes use of
the return value.

> +		}
> +
> +		fgi = (rxfs & RXFS_FGI_MASK) >> RXFS_FGI_OFF;

BTW: Is this a _real_ fifo? Or evolution of the c_can/d_can interface
where it's not a fifo at all.

> +		flags = readl(priv->mram_base + priv->rxf0_off + fgi * 16);
> +		if (flags & RX_BUF_XTD)
> +			frame->can_id = (flags & CAN_EFF_MASK) | CAN_EFF_FLAG;
> +		else
> +			frame->can_id = (flags >> 18) & CAN_SFF_MASK;
> +		netdev_dbg(dev, "R0 0x%x\n", flags);

please remove dbg
> +
> +		if (flags & RX_BUF_RTR) {
> +			frame->can_id |= CAN_RTR_FLAG;
> +		} else {
> +			flags = readl(priv->mram_base +
> +					priv->rxf0_off + fgi * 16 + 0x4);
> +			frame->can_dlc = get_can_dlc((flags >> 16) & 0x0F);
> +			netdev_dbg(dev, "R1 0x%x\n", flags);

please remove

> +
> +			*(u32 *)(frame->data + 0) = readl(priv->mram_base +
> +					priv->rxf0_off + fgi * 16 + 0x8);
> +			*(u32 *)(frame->data + 4) = readl(priv->mram_base +
> +					priv->rxf0_off + fgi * 16 + 0xC);

can you create a wrapper function to hide the pointer arithmetics here?
Somethig like m_can_read_fifo()

> +			netdev_dbg(dev, "R2 0x%x\n", *(u32 *)(frame->data + 0));
> +			netdev_dbg(dev, "R3 0x%x\n", *(u32 *)(frame->data + 4));
> +		}
> +
> +		/* acknowledge rx fifo 0 */
> +		m_can_write(priv, M_CAN_RXF0A, fgi);
> +
> +		netif_receive_skb(skb);
> +		netdev_dbg(dev, "new packet received\n");
> +
> +		stats->rx_packets++;
> +		stats->rx_bytes += frame->can_dlc;

Please move the stats handling in front of netif_receive_skb() as the
skb and thus frame is not a valid pointer anymore.

> +
> +		can_led_event(dev, CAN_LED_EVENT_RX);

Please move out of the loop so that it is just called once (if a CAN
frame is rx'ed) per  m_can_do_rx_poll().

> +
> +		quota--;
> +		num_rx_pkts++;
> +		rxfs = m_can_read(priv, M_CAN_RXF0S);
> +	};
> +
> +	return num_rx_pkts;
> +}
> +
> +static int m_can_poll(struct napi_struct *napi, int quota)
> +{
> +	struct net_device *dev = napi->dev;
> +	struct m_can_priv *priv = netdev_priv(dev);
> +	u32 work_done = 0;

Pleas make work_done a int, as it is retuned by this funtcion.

> +	u32 irqstatus;
> +
> +	irqstatus = m_can_read(priv, M_CAN_IR);
> +	if (irqstatus)
> +		netdev_dbg(dev, "irqstatus updated! new 0x%x old 0x%x rxf0s 0x%x\n",
> +			irqstatus, priv->irqstatus,
> +			m_can_read(priv, M_CAN_RXF0S));

Please remove debug.

> +
> +	irqstatus = irqstatus | priv->irqstatus;
> +	if (!irqstatus)
> +		goto end;
> +
> +	if (irqstatus & IR_RF0N)
> +		/* handle events corresponding to receive message objects */
> +		work_done += m_can_do_rx_poll(dev, (quota - work_done));
> +
> +	if (work_done < quota) {
> +		napi_complete(napi);
> +		/* enable all IRQs */
> +		m_can_enable_all_interrupts(priv, true);
> +	}
> +
> +end:
> +	return work_done;
> +}
> +
> +static irqreturn_t m_can_isr(int irq, void *dev_id)
> +{
> +	struct net_device *dev = (struct net_device *)dev_id;
> +	struct m_can_priv *priv = netdev_priv(dev);
> +	struct net_device_stats *stats = &dev->stats;
> +	u32 ir;
> +
> +	ir = m_can_read(priv, M_CAN_IR);
> +	if (!ir)
> +		return IRQ_NONE;
> +
> +	netdev_dbg(dev, "ir 0x%x rxfs0 0x%x\n", ir,
> +			m_can_read(priv, M_CAN_RXF0S));

please remove

> +
> +	/* ACK all irqs */
> +	if (ir & IR_ALL_INT)
> +		m_can_write(priv, M_CAN_IR, ir);
> +
> +	if (ir & IR_ERR_ALL) {
> +		netdev_dbg(dev, "bus error\n");
> +		/* TODO: handle bus error */
> +	}
> +
> +	/* save irqstatus for later using */
> +	priv->irqstatus = ir;
> +
> +	/*
> +	 * schedule NAPI in case of
> +	 * - rx IRQ
> +	 * - state change IRQ(TODO)
> +	 * - bus error IRQ and bus error reporting (TODO)
> +	 */
> +	if (ir & IR_RF0N) {
> +		m_can_enable_all_interrupts(priv, false);
> +		napi_schedule(&priv->napi);
> +	}
> +
> +	/* FIFO overflow */
> +	if (ir & IR_RF0L) {
> +		dev->stats.rx_over_errors++;
> +		dev->stats.rx_errors++;
> +	}
> +
> +	/* transmission complete interrupt */
> +	if (ir & IR_TC) {
> +		netdev_dbg(dev, "tx complete\n");
> +		stats->tx_bytes += can_get_echo_skb(dev, 0);
> +		stats->tx_packets++;
> +		can_led_event(dev, CAN_LED_EVENT_TX);
> +		netif_wake_queue(dev);
> +	}
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static const struct can_bittiming_const m_can_bittiming_const = {
> +	.name = KBUILD_MODNAME,
> +	.tseg1_min = 2,		/* Time segment 1 = prop_seg + phase_seg1 */
> +	.tseg1_max = 64,
> +	.tseg2_min = 1,		/* Time segment 2 = phase_seg2 */
> +	.tseg2_max = 16,
> +	.sjw_max = 16,
> +	.brp_min = 1,
> +	.brp_max = 1024,
> +	.brp_inc = 1,
> +};
> +
> +static int m_can_set_bittiming(struct net_device *dev)
> +{
> +	struct m_can_priv *priv = netdev_priv(dev);
> +	const struct can_bittiming *bt = &priv->can.bittiming;
> +	u16 brp, sjw, tseg1, tseg2;
> +	u32 reg_btp;
> +
> +	brp = bt->brp - 1;
> +	sjw = bt->sjw - 1;
> +	tseg1 = bt->prop_seg + bt->phase_seg1 - 1;
> +	tseg2 = bt->phase_seg2 - 1;
> +	reg_btp = (brp << BTR_BRP_SHIFT) | (sjw << BTR_SJW_SHIFT) |
> +			(tseg1 << BTR_TSEG1_SHIFT) | (tseg2 << BTR_TSEG2_SHIFT);
> +	m_can_write(priv, M_CAN_BTP, reg_btp);
> +	netdev_dbg(dev, "setting BTP 0x%x\n", reg_btp);
> +
> +	return 0;
> +}
> +
> +/*
> + * Configure M_CAN chip:
> + * - set rx buffer/fifo element size
> + * - configure rx fifo
> + * - accept non-matching frame into fifo 0
> + * - configure tx buffer
> + * - setup bittiming
> + * - TODO:
> + *   1) other working modes support like monitor, loopback...
> + *   2) lec error status report enable
> + */
> +static void m_can_chip_config(struct net_device *dev)
> +{
> +	struct m_can_priv *priv = netdev_priv(dev);
> +
> +	m_can_config_endisable(priv, true);
> +
> +	/* RX Buffer/FIFO Element Size 8 bytes data field */
> +	m_can_write(priv, M_CAN_RXESC, M_CAN_RXESC_8BYTES);
> +
> +	/* Accept Non-matching Frames Into FIFO 0 */
> +	m_can_write(priv, M_CAN_GFC, 0x0);
> +
> +	/* only support one Tx Buffer currently */
> +	m_can_write(priv, M_CAN_TXBC, (1 << TXBC_NDTB_OFF) |
> +		(priv->mram_off + priv->txb_off));
> +
> +	/* only support 8 bytes firstly */
> +	m_can_write(priv, M_CAN_TXESC, TXESC_TBDS_8BYTES);
> +
> +	m_can_write(priv, M_CAN_TXEFC, 0x00010000 |
> +		(priv->mram_off + priv->txe_off));
> +
> +	/* rx fifo configuration, blocking mode, fifo size 1 */
> +	m_can_write(priv, M_CAN_RXF0C, (priv->rxf0_elems << RXFC_FS_OFF) |
> +		RXFC_FWM_1 | (priv->mram_off + priv->rxf0_off));
> +
> +	m_can_write(priv, M_CAN_RXF1C, (priv->rxf1_elems << RXFC_FS_OFF) |
> +		RXFC_FWM_1 | (priv->mram_off + priv->rxf1_off));
> +
> +	/* enable all interrupts */
> +	m_can_write(priv, M_CAN_IR, IR_ALL_INT);
> +	m_can_write(priv, M_CAN_IE, IR_ALL_INT);
> +	m_can_write(priv, M_CAN_ILS, 0xFFFF0000);
                                     ^^^^^^^^^^

A define would be nice.

> +
> +	/* set bittiming params */
> +	m_can_set_bittiming(dev);
> +
> +	m_can_config_endisable(priv, false);
> +}
> +
> +static void m_can_start(struct net_device *dev)
> +{
> +	struct m_can_priv *priv = netdev_priv(dev);
> +
> +	/* basic m_can configuration */
> +	m_can_chip_config(dev);
> +
> +	priv->can.state = CAN_STATE_ERROR_ACTIVE;
> +
> +	/* enable status change, error and module interrupts */
> +	m_can_enable_all_interrupts(priv, true);
> +}
> +
> +static int m_can_set_mode(struct net_device *dev, enum can_mode mode)
> +{
> +	switch (mode) {
> +	case CAN_MODE_START:
> +		m_can_start(dev);
> +		netif_wake_queue(dev);
> +		break;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	return 0;
> +}
> +
> +static int m_can_get_berr_counter(const struct net_device *dev,
> +				  struct can_berr_counter *bec)
> +{
> +	/* TODO */
> +
> +	return 0;
> +}
> +
> +static void free_m_can_dev(struct net_device *dev)
> +{
> +	free_candev(dev);
> +}
> +
> +static struct net_device *alloc_m_can_dev(void)
> +{
> +	struct net_device *dev;
> +	struct m_can_priv *priv;
> +
> +	dev = alloc_candev(sizeof(struct m_can_priv), 1);
> +	if (!dev)
> +		return NULL;
> +
> +	priv = netdev_priv(dev);
> +	netif_napi_add(dev, &priv->napi, m_can_poll, M_CAN_NAPI_WEIGHT);
> +
> +	priv->dev = dev;
> +	priv->can.bittiming_const = &m_can_bittiming_const;
> +	priv->can.do_set_mode = m_can_set_mode;
> +	priv->can.do_get_berr_counter = m_can_get_berr_counter;
> +	priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
> +					CAN_CTRLMODE_LISTENONLY |
> +					CAN_CTRLMODE_BERR_REPORTING;

Are you taking care of all ctrlmodes you claim to support here?

> +
> +	return dev;
> +}
> +
> +static int m_can_open(struct net_device *dev)
> +{
> +	int err;
> +	struct m_can_priv *priv = netdev_priv(dev);
> +
> +	clk_prepare_enable(priv->clk);
> +
> +	/* open the can device */
> +	err = open_candev(dev);
> +	if (err) {
> +		netdev_err(dev, "failed to open can device\n");
> +		goto exit_open_fail;
> +	}
> +
> +	/* register interrupt handler */
> +	err = request_irq(dev->irq, m_can_isr, IRQF_SHARED, dev->name,
> +				dev);
> +	if (err < 0) {
> +		netdev_err(dev, "failed to request interrupt\n");
> +		goto exit_irq_fail;
> +	}
> +
> +	/* start the m_can controller */
> +	m_can_start(dev);
> +
> +	can_led_event(dev, CAN_LED_EVENT_OPEN);
> +	napi_enable(&priv->napi);
> +	netif_start_queue(dev);
> +
> +	return 0;
> +
> +exit_irq_fail:
> +	close_candev(dev);
> +exit_open_fail:
> +	clk_disable_unprepare(priv->clk);
> +	return err;
> +}
> +
> +static void m_can_stop(struct net_device *dev)
> +{
> +	struct m_can_priv *priv = netdev_priv(dev);
> +
> +	/* disable all interrupts */
> +	m_can_enable_all_interrupts(priv, false);
> +
> +	/* set the state as STOPPED */
> +	priv->can.state = CAN_STATE_STOPPED;
> +}
> +
> +static int m_can_close(struct net_device *dev)
> +{
> +	struct m_can_priv *priv = netdev_priv(dev);
> +
> +	netif_stop_queue(dev);
> +	napi_disable(&priv->napi);
> +	m_can_stop(dev);
> +	free_irq(dev->irq, dev);
> +	close_candev(dev);
> +	can_led_event(dev, CAN_LED_EVENT_STOP);
> +
> +	return 0;
> +}
> +
> +static netdev_tx_t m_can_start_xmit(struct sk_buff *skb,
> +					struct net_device *dev)
> +{
> +	struct m_can_priv *priv = netdev_priv(dev);
> +	struct can_frame *frame = (struct can_frame *)skb->data;
> +	u32 flags = 0, id;
> +
> +	if (can_dropped_invalid_skb(dev, skb))
> +		return NETDEV_TX_OK;
> +
> +	netif_stop_queue(dev);
> +
> +	if (frame->can_id & CAN_RTR_FLAG)
> +		flags |= TX_BUF_RTR;
> +
> +	if (frame->can_id & CAN_EFF_FLAG) {
> +		id = frame->can_id & CAN_EFF_MASK;
> +		flags |= TX_BUF_XTD;
> +	} else {
> +		id = ((frame->can_id & CAN_SFF_MASK) << 18);
> +	}
> +
> +	/* message ram configuration */
> +	writel(id | flags,
> +		priv->mram_base + priv->mram_off + priv->txb_off);
> +	writel(frame->can_dlc << 16,
> +		priv->mram_base + priv->mram_off + priv->txb_off + 0x4);
> +	writel(*(u32 *)(frame->data + 0),
> +		priv->mram_base + priv->mram_off + priv->txb_off + 0x8);
> +	writel(*(u32 *)(frame->data + 4),
> +		priv->mram_base + priv->mram_off + priv->txb_off + 0xc);

Here an inline function to hide the details of pointer arithmetics would
be nice.

> +
> +	can_put_echo_skb(skb, dev, 0);
> +
> +	/* enable first TX buffer to start transfer  */
> +	m_can_write(priv, M_CAN_TXBTIE, 0x00000001);
> +	m_can_write(priv, M_CAN_TXBAR, 0x00000001);
> +
> +	return NETDEV_TX_OK;
> +}
> +
> +static const struct net_device_ops m_can_netdev_ops = {
> +	.ndo_open = m_can_open,
> +	.ndo_stop = m_can_close,
> +	.ndo_start_xmit = m_can_start_xmit,
> +};
> +
> +static int register_m_can_dev(struct net_device *dev)
> +{
> +	dev->flags |= IFF_ECHO;	/* we support local echo */
> +	dev->netdev_ops = &m_can_netdev_ops;
> +
> +	return register_candev(dev);
> +}
> +
> +static const struct of_device_id m_can_of_table[] = {
> +	{ .compatible = "bosch,m_can", .data = NULL },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, m_can_of_table);
> +
> +static int m_can_of_parse_mram(struct platform_device *pdev,
> +				struct m_can_priv *priv)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct resource *res;
> +	void __iomem *addr;
> +	u32 out_val[8];
> +	int ret;
> +
> +	/* message ram could be shared */
> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "message_ram");
> +	if (!res)
> +		return -ENODEV;
> +
> +	addr = devm_ioremap(&pdev->dev, res->start, resource_size(res));
> +	if (!addr)
> +		return -ENODEV;
> +
> +	/* get message ram configuration */
> +	ret = of_property_read_u32_array(np, "mram-cfg",
> +				out_val, sizeof(out_val) / 4);
> +	if (ret) {
> +		dev_err(&pdev->dev, "can not get message ram configuration\n");
> +		return -ENODEV;
> +	}
> +
> +	priv->mram_base = addr;
> +	priv->mram_off = out_val[0];
> +	priv->sidf_elems = out_val[1];
> +	priv->sidf_off = priv->mram_off;
> +	priv->xidf_elems = out_val[2];
> +	priv->xidf_off = priv->sidf_off + priv->sidf_elems * SIDF_ELEMENT_SIZE;
> +	priv->rxf0_elems = out_val[3] & RXFC_FS_MASK;
> +	priv->rxf0_off = priv->xidf_off + priv->xidf_elems * XIDF_ELEMENT_SIZE;
> +	priv->rxf1_elems = out_val[4] & RXFC_FS_MASK;
> +	priv->rxf1_off = priv->rxf0_off + priv->rxf0_elems * RXF0_ELEMENT_SIZE;
> +	priv->rxb_elems = out_val[5];
> +	priv->rxb_off = priv->rxf1_off + priv->rxf1_elems * RXF1_ELEMENT_SIZE;
> +	priv->txe_elems = out_val[6];
> +	priv->txe_off = priv->rxb_off + priv->rxb_elems * RXB_ELEMENT_SIZE;
> +	priv->txb_elems = out_val[7] & TXBC_NDTB_MASK;
> +	priv->txb_off = priv->txe_off + priv->txe_elems * TXE_ELEMENT_SIZE;
> +
> +	dev_dbg(&pdev->dev, "mram_base =%p mram_off =0x%x "
> +		"sidf %d xidf %d rxf0 %d rxf1 %d rxb %d txe %d txb %d\n",
> +		priv->mram_base, priv->mram_off, priv->sidf_elems,
> +		priv->xidf_elems, priv->rxf0_elems, priv->rxf1_elems,
> +		priv->rxb_elems, priv->txe_elems, priv->txb_elems);
> +
> +	return 0;
> +}
> +
> +static int m_can_plat_probe(struct platform_device *pdev)
> +{
> +	struct net_device *dev;
> +	struct m_can_priv *priv;
> +	struct pinctrl *pinctrl;
> +	struct resource *res;
> +	void __iomem *addr;
> +	struct clk *clk;
> +	int irq, ret;
> +
> +	pinctrl = devm_pinctrl_get_select_default(&pdev->dev);
> +	if (IS_ERR(pinctrl))
> +		dev_warn(&pdev->dev,
> +			"failed to configure pins from driver\n");
> +
> +	clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(clk)) {
> +		dev_err(&pdev->dev, "no clock find\n");
> +		return PTR_ERR(clk);
> +	}
> +
> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "canfd");
> +	addr = devm_ioremap_resource(&pdev->dev, res);
> +	irq = platform_get_irq(pdev, 0);
> +	if (IS_ERR(addr) || irq < 0)
> +		return -EINVAL;
> +
> +	/* allocate the m_can device */
> +	dev = alloc_m_can_dev();
> +	if (!dev)
> +		return -ENOMEM;
> +
> +	priv = netdev_priv(dev);
> +	dev->irq = irq;
> +	priv->base = addr;
> +	priv->device = &pdev->dev;
> +	priv->clk = clk;
> +	priv->can.clock.freq = clk_get_rate(clk);
> +
> +	ret = m_can_of_parse_mram(pdev, priv);
> +	if (ret)
> +		goto failed_free_dev;
> +
> +	platform_set_drvdata(pdev, dev);
> +	SET_NETDEV_DEV(dev, &pdev->dev);
> +
> +	ret = register_m_can_dev(dev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "registering %s failed (err=%d)\n",
> +			KBUILD_MODNAME, ret);
> +		goto failed_free_dev;
> +	}
> +
> +	devm_can_led_init(dev);
> +
> +	dev_info(&pdev->dev, "%s device registered (regs=%p, irq=%d)\n",
> +		 KBUILD_MODNAME, priv->base, dev->irq);
> +
> +	return 0;
> +
> +failed_free_dev:
> +	free_m_can_dev(dev);
> +	return ret;
> +}
> +
> +#ifdef CONFIG_PM

please remove and use __maybe_unused unstead

> +static int m_can_suspend(struct device *dev)
> +{
> +	struct net_device *ndev = dev_get_drvdata(dev);
> +	struct m_can_priv *priv = netdev_priv(ndev);
> +
> +	if (netif_running(ndev)) {
> +		netif_stop_queue(ndev);
> +		netif_device_detach(ndev);
> +	}
> +
> +	/* TODO: enter low power */
> +
> +	priv->can.state = CAN_STATE_SLEEPING;
> +
> +	return 0;
> +}
> +
> +static int m_can_resume(struct device *dev)
> +{
> +	struct net_device *ndev = dev_get_drvdata(dev);
> +	struct m_can_priv *priv = netdev_priv(ndev);
> +
> +	/* TODO: exit low power */
> +
> +	priv->can.state = CAN_STATE_ERROR_ACTIVE;
> +
> +	if (netif_running(ndev)) {
> +		netif_device_attach(ndev);
> +		netif_start_queue(ndev);
> +	}
> +
> +	return 0;
> +}
> +#endif
> +
> +static void unregister_m_can_dev(struct net_device *dev)
> +{
> +	unregister_candev(dev);
> +}
> +
> +static int m_can_plat_remove(struct platform_device *pdev)
> +{
> +	struct net_device *dev = platform_get_drvdata(pdev);
> +
> +	unregister_m_can_dev(dev);
> +	platform_set_drvdata(pdev, NULL);
> +
> +	free_m_can_dev(dev);
> +
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops m_can_pmops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(m_can_suspend, m_can_resume)
> +};
> +
> +static struct platform_driver m_can_plat_driver = {
> +	.driver = {
> +		.name = KBUILD_MODNAME,
> +		.owner = THIS_MODULE,
> +		.of_match_table = of_match_ptr(m_can_of_table),
> +		.pm     = &m_can_pmops,
> +	},
> +	.probe = m_can_plat_probe,
> +	.remove = m_can_plat_remove,
> +};
> +
> +module_platform_driver(m_can_plat_driver);
> +
> +MODULE_AUTHOR("Dong Aisheng <[email-masked]>");
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("CAN bus driver for Bosch M_CAN controller");
> 

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |