Re: [PATCH net-next 08/12] net: dsa: rzn1-a5psw: add FDB support

[Vladimir Oltean]

On Thu, Apr 14, 2022 at 02:22:46PM +0200, Clément Léger wrote:
> This commits add forwarding database support to the driver. It
> implements fdb_add(), fdb_del() and fdb_dump().
> 
> Signed-off-by: Clément Léger <clement.leger@xxxxxxxxxxx>
> ---
>  drivers/net/dsa/rzn1_a5psw.c | 163 +++++++++++++++++++++++++++++++++++
>  drivers/net/dsa/rzn1_a5psw.h |  16 ++++
>  2 files changed, 179 insertions(+)
> 
> diff --git a/drivers/net/dsa/rzn1_a5psw.c b/drivers/net/dsa/rzn1_a5psw.c
> index 7ab7d9054427..8c763c2a1a1f 100644
> --- a/drivers/net/dsa/rzn1_a5psw.c
> +++ b/drivers/net/dsa/rzn1_a5psw.c
> @@ -369,6 +369,166 @@ static void a5psw_port_fast_age(struct dsa_switch *ds, int port)
>  	a5psw_port_fdb_flush(a5psw, port);
>  }
>  
> +static int a5psw_lk_execute_lookup(struct a5psw *a5psw, union lk_data *lk_data,
> +				   u16 *entry)
> +{
> +	u32 ctrl;
> +	int ret;
> +
> +	a5psw_reg_writel(a5psw, A5PSW_LK_DATA_LO, lk_data->lo);
> +	a5psw_reg_writel(a5psw, A5PSW_LK_DATA_HI, lk_data->hi);
> +
> +	ctrl = A5PSW_LK_ADDR_CTRL_LOOKUP;
> +	ret = a5psw_lk_execute_ctrl(a5psw, &ctrl);
> +	if (ret)
> +		return ret;
> +
> +	*entry = ctrl & A5PSW_LK_ADDR_CTRL_ADDRESS;
> +
> +	return 0;
> +}
> +
> +static int a5psw_port_fdb_add(struct dsa_switch *ds, int port,
> +			      const unsigned char *addr, u16 vid,
> +			      struct dsa_db db)

This isn't something that is documented because I haven't had time to
update that, but new drivers should comply to the requirements for FDB
isolation (not ignore the passed "db" here) and eventually set
ds->fdb_isolation = true. Doing so would allow your switch to behave
correctly when
- there is more than one bridge spanning its ports,
- some ports are standalone and some ports are bridged
- standalone ports are looped back via an external cable with bridged
  ports
- unrecognized upper interfaces (bond, team) are used, and those are
  bridged directly with some other switch ports

The most basic thing you need to do to satisfy the requirements is to
figure out what mechanism for FDB partitioning does your hardware have.
If the answer is "none", then we'll have to use VLANs for that: all
standalone ports to share a VLAN, each VLAN-unaware bridge to share a
VLAN across all member ports, each VLAN of a VLAN-aware bridge to
reserve its own VLAN. Up to a total of 32 VLANs, since I notice that's
what the limit for your hardware is.

But I see this patch set doesn't include VLAN functionality (and also
ignores the "vid" from FDB entries), so I can't really say more right now.
But if you could provide more information about the hardware
capabilities we can discuss implementation options.

> +{
> +	struct a5psw *a5psw = ds->priv;
> +	union lk_data lk_data = {0};
> +	bool inc_learncount = false;
> +	int ret = 0;
> +	u16 entry;
> +	u32 reg;
> +
> +	ether_addr_copy(lk_data.entry.mac, addr);
> +	lk_data.entry.port_mask = BIT(port);
> +
> +	spin_lock(&a5psw->lk_lock);
> +
> +	/* Set the value to be written in the lookup table */
> +	ret = a5psw_lk_execute_lookup(a5psw, &lk_data, &entry);
> +	if (ret)
> +		goto lk_unlock;
> +
> +	lk_data.hi = a5psw_reg_readl(a5psw, A5PSW_LK_DATA_HI);
> +	if (!lk_data.entry.valid) {
> +		inc_learncount = true;
> +		/* port_mask set to 0x1f when entry is not valid, clear it */
> +		lk_data.entry.port_mask = 0;
> +		lk_data.entry.prio = 0;
> +	}
> +
> +	lk_data.entry.port_mask |= BIT(port);
> +	lk_data.entry.is_static = 1;
> +	lk_data.entry.valid = 1;
> +
> +	a5psw_reg_writel(a5psw, A5PSW_LK_DATA_HI, lk_data.hi);
> +
> +	reg = A5PSW_LK_ADDR_CTRL_WRITE | entry;
> +	ret = a5psw_lk_execute_ctrl(a5psw, &reg);
> +	if (ret)
> +		goto lk_unlock;
> +
> +	if (inc_learncount) {
> +		reg = A5PSW_LK_LEARNCOUNT_MODE_INC;
> +		a5psw_reg_writel(a5psw, A5PSW_LK_LEARNCOUNT, reg);
> +	}
> +
> +lk_unlock:
> +	spin_unlock(&a5psw->lk_lock);
> +
> +	return ret;
> +}
> +
> +static int a5psw_port_fdb_del(struct dsa_switch *ds, int port,
> +			      const unsigned char *addr, u16 vid,
> +			      struct dsa_db db)
> +{
> +	struct a5psw *a5psw = ds->priv;
> +	union lk_data lk_data = {0};
> +	bool clear = false;
> +	int ret = 0;
> +	u16 entry;
> +	u32 reg;
> +
> +	ether_addr_copy(lk_data.entry.mac, addr);
> +
> +	spin_lock(&a5psw->lk_lock);
> +
> +	ret = a5psw_lk_execute_lookup(a5psw, &lk_data, &entry);
> +	if (ret) {
> +		dev_err(a5psw->dev, "Failed to lookup mac address\n");
> +		goto lk_unlock;
> +	}
> +
> +	lk_data.hi = a5psw_reg_readl(a5psw, A5PSW_LK_DATA_HI);
> +	if (!lk_data.entry.valid) {
> +		dev_err(a5psw->dev, "Tried to remove non-existing entry\n");
> +		ret = -ENOENT;
> +		goto lk_unlock;
> +	}
> +
> +	lk_data.entry.port_mask &= ~BIT(port);
> +	/* If there is no more port in the mask, clear the entry */
> +	if (lk_data.entry.port_mask == 0)
> +		clear = true;
> +
> +	a5psw_reg_writel(a5psw, A5PSW_LK_DATA_HI, lk_data.hi);
> +
> +	reg = entry;
> +	if (clear)
> +		reg |= A5PSW_LK_ADDR_CTRL_CLEAR;
> +	else
> +		reg |= A5PSW_LK_ADDR_CTRL_WRITE;
> +
> +	ret = a5psw_lk_execute_ctrl(a5psw, &reg);
> +	if (ret)
> +		goto lk_unlock;
> +
> +	/* Decrement LEARNCOUNT */
> +	if (clear) {
> +		reg = A5PSW_LK_LEARNCOUNT_MODE_DEC;
> +		a5psw_reg_writel(a5psw, A5PSW_LK_LEARNCOUNT, reg);
> +	}
> +
> +lk_unlock:
> +	spin_unlock(&a5psw->lk_lock);
> +
> +	return ret;
> +}
> +
> +static int a5psw_port_fdb_dump(struct dsa_switch *ds, int port,
> +			       dsa_fdb_dump_cb_t *cb, void *data)
> +{
> +	struct a5psw *a5psw = ds->priv;
> +	union lk_data lk_data;
> +	int i = 0, ret;
> +	u32 reg;
> +
> +	for (i = 0; i < A5PSW_TABLE_ENTRIES; i++) {
> +		reg = A5PSW_LK_ADDR_CTRL_READ | A5PSW_LK_ADDR_CTRL_WAIT | i;
> +		spin_lock(&a5psw->lk_lock);
> +
> +		ret = a5psw_lk_execute_ctrl(a5psw, &reg);
> +		if (ret)
> +			return ret;
> +
> +		lk_data.hi = a5psw_reg_readl(a5psw, A5PSW_LK_DATA_HI);
> +		/* If entry is not valid or does not contain the port, skip */
> +		if (!lk_data.entry.valid ||
> +		    !(lk_data.entry.port_mask & BIT(port))) {
> +			spin_unlock(&a5psw->lk_lock);
> +			continue;
> +		}
> +
> +		lk_data.lo = a5psw_reg_readl(a5psw, A5PSW_LK_DATA_LO);
> +		spin_unlock(&a5psw->lk_lock);
> +
> +		cb(lk_data.entry.mac, 0, lk_data.entry.is_static, data);

ret = cb(...)
if (ret)
	return ret;

This actually matters because the netlink skb used for the FDB dump may
run out of space and you'll have missing FDB entries.

> +	}
> +
> +	return 0;
> +}
> +
>  static void a5psw_get_strings(struct dsa_switch *ds, int port, u32 stringset,
>  			      uint8_t *data)
>  {
> @@ -500,6 +660,9 @@ const struct dsa_switch_ops a5psw_switch_ops = {
>  	.port_bridge_leave = a5psw_port_bridge_leave,
>  	.port_stp_state_set = a5psw_port_stp_state_set,
>  	.port_fast_age = a5psw_port_fast_age,
> +	.port_fdb_add = a5psw_port_fdb_add,
> +	.port_fdb_del = a5psw_port_fdb_del,
> +	.port_fdb_dump = a5psw_port_fdb_dump,
>  
>  };
>  
> diff --git a/drivers/net/dsa/rzn1_a5psw.h b/drivers/net/dsa/rzn1_a5psw.h
> index b34ea549e936..37aa89383e70 100644
> --- a/drivers/net/dsa/rzn1_a5psw.h
> +++ b/drivers/net/dsa/rzn1_a5psw.h
> @@ -167,6 +167,22 @@
>  #define A5PSW_CTRL_TIMEOUT		1000
>  #define A5PSW_TABLE_ENTRIES		8192
>  
> +struct fdb_entry {

Shouldn't this contain something along the lines of a VID, FID, something?

> +	u8 mac[ETH_ALEN];
> +	u8 valid:1;
> +	u8 is_static:1;
> +	u8 prio:3;
> +	u8 port_mask:5;
> +} __packed;
> +
> +union lk_data {
> +	struct {
> +		u32 lo;
> +		u32 hi;
> +	};
> +	struct fdb_entry entry;
> +};
> +
>  /**
>   * struct a5psw - switch struct
>   * @base: Base address of the switch
> -- 
> 2.34.1
>