Re: [PATCH v2 3/4] can: Add driver for CAST CAN Bus Controller

Andrew Lunn
2024-09-22T16:34:27Z

> +static inline u32 ccan_read_reg(const struct ccan_priv *priv, u8 reg)
> +{
> + return ioread32(priv->reg_base + reg);
> +}
> +
> +static inline void ccan_write_reg(const struct ccan_priv *priv, u8 reg, u32 value)
> +{
> + iowrite32(value, priv->reg_base + reg);
> +}

No inline functions in .c files please. Let the compiler decide.

> +static inline u8 ccan_read_reg_8bit(const struct ccan_priv *priv,
> + enum ccan_reg reg)
> +{
> + u8 reg_down;
> + union val {
> + u8 val_8[4];
> + u32 val_32;
> + } val;
> +
> + reg_down = ALIGN_DOWN(reg, 4);
> + val.val_32 = ccan_read_reg(priv, reg_down);
> + return val.val_8[reg - reg_down];

There is an ioread8(). Is it invalid to do a byte read for this
hardware? If so, it is probably worth a comment.

> +static int ccan_bittime_configuration(struct net_device *ndev)
> +{
> + struct ccan_priv *priv = netdev_priv(ndev);
> + struct can_bittiming *bt = &priv->can.bittiming;
> + struct can_bittiming *dbt = &priv->can.data_bittiming;
> + u32 bittiming, data_bittiming;
> + u8 reset_test;
> +
> + reset_test = ccan_read_reg_8bit(priv, CCAN_CFG_STAT);
> +
> + if (!(reset_test & CCAN_RST_MASK)) {
> + netdev_alert(ndev, "Not in reset mode, cannot set bit timing\n");
> + return -EPERM;
> + }

You don't see nedev_alert() used very often. If this is fatal then
netdev_err().

Also, EPERM? man 3 errno say:

EPERM Operation not permitted (POSIX.1-2001).

Why is this a permission issue?

> +static void ccan_tx_interrupt(struct net_device *ndev, u8 isr)
> +{
> + struct ccan_priv *priv = netdev_priv(ndev);
> +
> + /* wait till transmission of the PTB or STB finished */
> + while (isr & (CCAN_TPIF_MASK | CCAN_TSIF_MASK)) {
> + if (isr & CCAN_TPIF_MASK)
> + ccan_reg_set_bits(priv, CCAN_RTIF, CCAN_TPIF_MASK);
> +
> + if (isr & CCAN_TSIF_MASK)
> + ccan_reg_set_bits(priv, CCAN_RTIF, CCAN_TSIF_MASK);
> +
> + isr = ccan_read_reg_8bit(priv, CCAN_RTIF);
> + }

Potentially endless loops like this are a bad idea. If the firmware
crashes, you are never getting out of here. Please use one of the
macros from iopoll.h

> +static irqreturn_t ccan_interrupt(int irq, void *dev_id)
> +{
> + struct net_device *ndev = (struct net_device *)dev_id;

dev_id is a void *, so you don't need the cast.

Andrew