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Date: Sat, 02 Nov 2013 01:24:15 +0300
From: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To: Wolfgang Grandegger <wg@...ndegger.com>, netdev@...r.kernel.org,
mkl@...gutronix.de, linux-can@...r.kernel.org
CC: linux-sh@...r.kernel.org, vksavl@...il.com
Subject: Re: [PATCH v2] can: add Renesas R-Car CAN driver
On 10/25/2013 11:28 PM, Wolfgang Grandegger wrote:
>> Add support for the CAN controller found in Renesas R-Car SoCs.
>> Signed-off-by: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
[...]
>> Index: linux-can-next/drivers/net/can/rcar_can.c
>> ===================================================================
>> --- /dev/null
>> +++ linux-can-next/drivers/net/can/rcar_can.c
>> @@ -0,0 +1,920 @@
[...]
>> +static bool autorecovery;
>> +module_param(autorecovery, bool, 0644);
>> +MODULE_PARM_DESC(autorecovery, "Automatic hardware recovery from bus-off");
> Software recovery is the preferred solution. No need to support
> automatic recovery by the hardware.
OK, removed it.
>> +/* Mailbox registers structure */
>> +struct rcar_can_mbox_regs {
>> + u32 id; /* IDE and RTR bits, SID and EID */
>> + u8 stub; /* Not used */
>> + u8 dlc; /* Data Length Code - bits [0..3] */
>> + u8 data[8]; /* Data Bytes */
>> + u8 tsh; /* Time Stamp Higher Byte */
>> + u8 tsl; /* Time Stamp Lower Byte */
> I would add padding bytes here to ensure alignment.
What padding? This is how the hardware registers are laid out. I think I
should rather add __packed after }.
>> +};
>> +
>> +struct rcar_can_regs {
>> + struct rcar_can_mbox_regs mb[N_MBX];
>> +};
> Where are the other registers? Using a mix of struct and #define offsets
> is really ugly.
OK, fixed. I just thought using {read|write}[bwl]() doesn't buy us any
type checking anyway, so was being lazy here.
>> +struct rcar_can_priv {
>> + struct can_priv can; /* Must be the first member! */
>> + struct net_device *ndev;
>> + struct napi_struct napi;
>> + struct rcar_can_regs __iomem *regs;
>> + struct clk *clk;
>> + spinlock_t mier_lock;
>> + u8 clock_select;
>> + u8 ier;
> s/ier/ier_shadow/ ?
I'd rather leave it as is... hoping you won't insist.
>> +};
>> +static void rcar_can_start(struct net_device *ndev);
> Forward declarations should be avoided.
Removed it since it's not needed anymore.
>> +
>> +static void rcar_can_error(struct net_device *ndev)
>> +{
>> + struct rcar_can_priv *priv = netdev_priv(ndev);
>> + struct net_device_stats *stats = &ndev->stats;
>> + struct can_frame *cf;
>> + struct sk_buff *skb;
>> + u8 eifr, txerr = 0, rxerr = 0;
>> +
>> + /* Propagate the error condition to the CAN stack */
>> + skb = alloc_can_err_skb(ndev, &cf);
>> + if (!skb)
>> + return;
>> + eifr = rcar_can_readb(priv, RCAR_CAN_EIFR);
>> + if (eifr & (EIFR_EWIF | EIFR_EPIF)) {
>> + cf->can_id |= CAN_ERR_CRTL;
>> + txerr = rcar_can_readb(priv, RCAR_CAN_TECR);
>> + rxerr = rcar_can_readb(priv, RCAR_CAN_RECR);
> Could you please add these values to data[6..7] as shown here:
> http://lxr.free-electrons.com/source/drivers/net/can/sja1000/sja1000.c#L475
OK.
>> + }
>> + if (eifr & EIFR_BEIF) {
>> + int rx_errors = 0, tx_errors = 0;
>> + u8 ecsr;
>> +
>> + if (priv->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT)
>> + tx_failure_cleanup(ndev);
>> + netdev_dbg(priv->ndev, "Bus error interrupt:\n");
>> + cf->can_id |= CAN_ERR_BUSERROR | CAN_ERR_PROT;
>> + cf->data[2] = CAN_ERR_PROT_UNSPEC;
>> +
>> + ecsr = rcar_can_readb(priv, RCAR_CAN_ECSR);
>> + if (ecsr & ECSR_ADEF) {
>> + netdev_dbg(priv->ndev, "ACK Delimiter Error\n");
>> + cf->data[3] |= CAN_ERR_PROT_LOC_ACK_DEL;
>> + tx_errors++;
>> + rcar_can_writeb(priv, RCAR_CAN_ECSR, (u8)~ECSR_ADEF);
> Please avoid casts here and below.
These casts help avoid compiler warnings.
[...]
>> + if (eifr & EIFR_BORIF) {
>> + netdev_dbg(priv->ndev, "Bus-off recovery interrupt\n");
>> + priv->can.state = CAN_STATE_ERROR_ACTIVE;
>> + cf->can_id |= CAN_ERR_RESTARTED;
> Does this interrupt come when Bus-off recovery has compeleted (back to
> error-active?) CAN_ERR_RESTARTED should be reported when the bus-off
> recovery has been triggered. It takes some time before it is really
> completed.
Removed the handler.
>> + if (eifr & EIFR_OLIF) {
>> + netdev_dbg(priv->ndev,
>> + "Overload Frame Transmission error interrupt\n");
>> + cf->can_id |= CAN_ERR_PROT;
>> + cf->data[2] |= CAN_ERR_PROT_OVERLOAD;
>> + ndev->stats.rx_over_errors++;
>> + ndev->stats.rx_errors++;
>> + rcar_can_writeb(priv, RCAR_CAN_EIFR, (u8)~EIFR_OLIF);
> No unnecessary casts please.
Unfortunately, they are necessary.
[...]
>> +static irqreturn_t rcar_can_interrupt(int irq, void *dev_id)
>> +{
>> + struct net_device *ndev = (struct net_device *)dev_id;
>> + struct rcar_can_priv *priv = netdev_priv(ndev);
>> + struct net_device_stats *stats = &ndev->stats;
>> + u8 isr;
>> +
>> + isr = rcar_can_readb(priv, RCAR_CAN_ISR);
>> + if (!(isr & priv->ier))
>> + return IRQ_NONE;
>> +
>> + if (isr & ISR_ERSF)
>> + rcar_can_error(ndev);
>> +
>> + if (isr & ISR_TXMF) {
>> + u32 ie_mask = 0;
>> + int i;
>> +
>> + /* Set Transmit Mailbox Search Mode */
>> + rcar_can_writeb(priv, RCAR_CAN_MSMR, MSMR_TXMB);
>> + for (i = 0; i < N_TX_MB; i++) {
>> + u8 mctl, mbx;
>> +
>> + mbx = rcar_can_readb(priv, RCAR_CAN_MSSR);
>> + if (mbx & MSSR_SEST)
>> + break;
>> + mbx &= MSSR_MBNST;
>> + stats->tx_bytes += readb(&priv->regs->mb[mbx].dlc);
>> + stats->tx_packets++;
>> + mctl = rcar_can_readb(priv, RCAR_CAN_MCTL(mbx));
>> + /* Bits SENTDATA and TRMREQ cannot be
>> + * set to 0 simultaneously
>> + */
>> + mctl &= ~MCTL_TRMREQ;
>> + rcar_can_writeb(priv, RCAR_CAN_MCTL(mbx), mctl);
>> + mctl &= ~MCTL_SENTDATA;
>> + /* Clear interrupt */
>> + rcar_can_writeb(priv, RCAR_CAN_MCTL(mbx), mctl);
>> + ie_mask |= BIT(mbx - FIRST_TX_MB);
>> + can_get_echo_skb(ndev, mbx - FIRST_TX_MB);
>> + can_led_event(ndev, CAN_LED_EVENT_TX);
>> + }
>> + /* Set receive mailbox search mode */
>> + rcar_can_writeb(priv, RCAR_CAN_MSMR, MSMR_RXMB);
>> + /* Disable mailbox interrupt, mark mailbox as free */
>> + if (ie_mask) {
>> + u32 mier1;
>> +
>> + spin_lock(&priv->mier_lock);
>> + mier1 = rcar_can_readl(priv, RCAR_CAN_MIER1);
>> + rcar_can_writel(priv, RCAR_CAN_MIER1, mier1 & ~ie_mask);
>> + spin_unlock(&priv->mier_lock);
>> + netif_wake_queue(ndev);
>> + }
>> + }
> Would be nice to have this in an (inline) function, like for the error
> handling above.
OK, but I guess *inline* keyword is not necessary as gcc should figure it
out itself, given only a single call.
[...]
>> +static int rcar_can_probe(struct platform_device *pdev)
>> +{
[...]
>> + ndev->netdev_ops = &rcar_can_netdev_ops;
>> + ndev->irq = irq;
>> + ndev->flags |= IFF_ECHO;
>> + priv->ndev = ndev;
>> + priv->regs = (struct rcar_can_regs *)addr;
> Is this cast needed?
Not really, removed it.
[...]
> Wolfgang.
WBR, Sergei
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