[net-next RFC PATCH v4 12/15] net: dsa: qca8k: add support for mdio read/write in Ethernet packet

Ansuel Smith
2021-12-11T19:58:38Z

Add qca8k side support for mdio read/write in Ethernet packet.
qca8k supports some specially crafted Ethernet packet that can be used
for mdio read/write instead of the legacy method uart/internal mdio.
This add support for the qca8k side to craft the packet and enqueue it.
Each port and the qca8k_priv have a special struct to put data in it.
The completion API is used to wait for the packet to be received back
with the requested data.

The various steps are:
1. Craft the special packet with the qca hdr set to mdio read/write
mode.
2. Set the lock in the dedicated mdio struct.
3. Reinit the completion.
4. Enqueue the packet.
5. Wait the packet to be received.
6. Use the data set by the tagger to complete the mdio operation.

If the completion timeouts or the ack value is not true, the legacy
mdio way is used.

It has to be considered that in the initial setup mdio is still used and
mdio is still used until DSA is ready to accept and tag packet.

tag_proto_connect() is used to fill the required handler for the tagger
to correctly parse and elaborate the special Ethernet mdio packet.

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
---
drivers/net/dsa/qca8k.c | 189 +++++++++++++++++++++++++++++++++++-
drivers/net/dsa/qca8k.h | 12 +++
include/linux/dsa/tag_qca.h | 2 +-
3 files changed, 201 insertions(+), 2 deletions(-)

diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
index 905fae26e05b..0f1a604f015e 100644
--- a/drivers/net/dsa/qca8k.c
+++ b/drivers/net/dsa/qca8k.c
@@ -20,6 +20,7 @@
#include <linux/phylink.h>
#include <linux/gpio/consumer.h>
#include <linux/etherdevice.h>
+#include <linux/dsa/tag_qca.h>

#include "qca8k.h"

@@ -170,6 +171,157 @@ qca8k_rmw(struct qca8k_priv *priv, u32 reg, u32 mask, u32 write_val)
return regmap_update_bits(priv->regmap, reg, mask, write_val);
}

+static void qca8k_rw_reg_ack_handler(struct dsa_port *dp, struct sk_buff *skb)
+{
+ struct qca8k_mdio_hdr_data *mdio_hdr_data;
+ struct qca8k_priv *priv = dp->ds->priv;
+ struct mdio_ethhdr *mdio_ethhdr;
+ u8 len, cmd;
+
+ mdio_ethhdr = (struct mdio_ethhdr *)skb_mac_header(skb);
+ mdio_hdr_data = &priv->mdio_hdr_data;
+
+ cmd = FIELD_GET(QCA_HDR_MDIO_CMD, mdio_ethhdr->command);
+ len = FIELD_GET(QCA_HDR_MDIO_LENGTH, mdio_ethhdr->command);
+
+ /* Make sure the seq match the requested packet */
+ if (mdio_ethhdr->seq == mdio_hdr_data->seq)
+ mdio_hdr_data->ack = true;
+
+ if (cmd == MDIO_READ) {
+ mdio_hdr_data->data[0] = mdio_ethhdr->mdio_data;
+
+ /* Get the rest of the 12 byte of data */
+ if (len > QCA_HDR_MDIO_DATA1_LEN)
+ memcpy(mdio_hdr_data->data + 1, skb->data,
+ QCA_HDR_MDIO_DATA2_LEN);
+ }
+
+ complete(&mdio_hdr_data->rw_done);
+}
+
+static struct sk_buff *qca8k_alloc_mdio_header(enum mdio_cmd cmd, u32 reg, u32 *val,
+ int seq_num)
+{
+ struct mdio_ethhdr *mdio_ethhdr;
+ struct sk_buff *skb;
+ u16 hdr;
+
+ skb = dev_alloc_skb(QCA_HDR_MDIO_PKG_LEN);
+
+ prefetchw(skb->data);
+
+ skb_reset_mac_header(skb);
+ skb_set_network_header(skb, skb->len);
+
+ mdio_ethhdr = skb_push(skb, QCA_HDR_MDIO_HEADER_LEN + QCA_HDR_LEN);
+
+ hdr = FIELD_PREP(QCA_HDR_XMIT_VERSION, QCA_HDR_VERSION);
+ hdr |= QCA_HDR_XMIT_FROM_CPU;
+ hdr |= FIELD_PREP(QCA_HDR_XMIT_DP_BIT, BIT(0));
+ hdr |= FIELD_PREP(QCA_HDR_XMIT_CONTROL, QCA_HDR_XMIT_TYPE_RW_REG);
+
+ mdio_ethhdr->seq = FIELD_PREP(QCA_HDR_MDIO_SEQ_NUM, seq_num);
+
+ mdio_ethhdr->command = FIELD_PREP(QCA_HDR_MDIO_ADDR, reg);
+ mdio_ethhdr->command |= FIELD_PREP(QCA_HDR_MDIO_LENGTH, 4);
+ mdio_ethhdr->command |= FIELD_PREP(QCA_HDR_MDIO_CMD, cmd);
+ mdio_ethhdr->command |= FIELD_PREP(QCA_HDR_MDIO_CHECK_CODE, MDIO_CHECK_CODE_VAL);
+
+ if (cmd == MDIO_WRITE)
+ mdio_ethhdr->mdio_data = *val;
+
+ mdio_ethhdr->hdr = htons(hdr);
+
+ skb_put_zero(skb, QCA_HDR_MDIO_DATA2_LEN);
+ skb_put_zero(skb, QCA_HDR_MDIO_PADDING_LEN);
+
+ return skb;
+}
+
+static int qca8k_read_eth(struct qca8k_priv *priv, u32 reg, u32 *val)
+{
+ struct qca8k_mdio_hdr_data *mdio_hdr_data = &priv->mdio_hdr_data;
+ struct sk_buff *skb;
+ bool ack;
+ int ret;
+
+ skb = qca8k_alloc_mdio_header(MDIO_READ, reg, NULL, 200);
+ skb->dev = dsa_to_port(priv->ds, 0)->master;
+
+ mutex_lock(&mdio_hdr_data->mutex);
+
+ reinit_completion(&mdio_hdr_data->rw_done);
+ mdio_hdr_data->seq = 200;
+ mdio_hdr_data->ack = false;
+
+ dev_queue_xmit(skb);
+
+ ret = wait_for_completion_timeout(&mdio_hdr_data->rw_done, QCA8K_ETHERNET_TIMEOUT);
+
+ *val = mdio_hdr_data->data[0];
+ ack = mdio_hdr_data->ack;
+
+ mutex_unlock(&mdio_hdr_data->mutex);
+
+ if (ret <= 0)
+ return -ETIMEDOUT;
+
+ if (!ack)
+ return -EINVAL;
+
+ return 0;
+}
+
+static int qca8k_write_eth(struct qca8k_priv *priv, u32 reg, u32 val)
+{
+ struct qca8k_mdio_hdr_data *mdio_hdr_data = &priv->mdio_hdr_data;
+ struct sk_buff *skb;
+ bool ack;
+ int ret;
+
+ skb = qca8k_alloc_mdio_header(MDIO_WRITE, reg, &val, 200);
+ skb->dev = dsa_to_port(priv->ds, 0)->master;
+
+ mutex_lock(&mdio_hdr_data->mutex);
+
+ reinit_completion(&mdio_hdr_data->rw_done);
+ mdio_hdr_data->ack = false;
+ mdio_hdr_data->seq = 200;
+
+ dev_queue_xmit(skb);
+
+ ret = wait_for_completion_timeout(&mdio_hdr_data->rw_done, QCA8K_ETHERNET_TIMEOUT);
+
+ ack = mdio_hdr_data->ack;
+
+ mutex_unlock(&mdio_hdr_data->mutex);
+
+ if (ret <= 0)
+ return -ETIMEDOUT;
+
+ if (!ack)
+ return -EINVAL;
+
+ return 0;
+}
+
+static int
+qca8k_regmap_update_bits_eth(struct qca8k_priv *priv, u32 reg, u32 mask, u32 write_val)
+{
+ u32 val = 0;
+ int ret;
+
+ ret = qca8k_read_eth(priv, reg, &val);
+ if (ret)
+ return ret;
+
+ val &= ~mask;
+ val |= write_val;
+
+ return qca8k_write_eth(priv, reg, val);
+}
+
static int
qca8k_regmap_read(void *ctx, uint32_t reg, uint32_t *val)
{
@@ -178,6 +330,9 @@ qca8k_regmap_read(void *ctx, uint32_t reg, uint32_t *val)
u16 r1, r2, page;
int ret;

+ if (priv->master_oper && !qca8k_read_eth(priv, reg, val))
+ return 0;
+
qca8k_split_addr(reg, &r1, &r2, &page);

mutex_lock_nested(&bus->mdio_lock, MDIO_MUTEX_NESTED);
@@ -201,6 +356,9 @@ qca8k_regmap_write(void *ctx, uint32_t reg, uint32_t val)
u16 r1, r2, page;
int ret;

+ if (priv->master_oper && !qca8k_write_eth(priv, reg, val))
+ return 0;
+
qca8k_split_addr(reg, &r1, &r2, &page);

mutex_lock_nested(&bus->mdio_lock, MDIO_MUTEX_NESTED);
@@ -225,6 +383,10 @@ qca8k_regmap_update_bits(void *ctx, uint32_t reg, uint32_t mask, uint32_t write_
u32 val;
int ret;

+ if (priv->master_oper &&
+ !qca8k_regmap_update_bits_eth(priv, reg, mask, write_val))
+ return 0;
+
qca8k_split_addr(reg, &r1, &r2, &page);

mutex_lock_nested(&bus->mdio_lock, MDIO_MUTEX_NESTED);
@@ -1232,7 +1394,7 @@ qca8k_setup(struct dsa_switch *ds)
}

/* Individual user ports get connected to CPU port only */
- if (dsa_is_user_port(ds, i)) {
+ if (dsa_is_dsa_port(ds, i)) {
ret = qca8k_rmw(priv, QCA8K_PORT_LOOKUP_CTRL(i),
QCA8K_PORT_LOOKUP_MEMBER,
BIT(cpu_port));
@@ -2395,6 +2557,30 @@ qca8k_master_change(struct dsa_switch *ds, const struct net_device *master,
priv->master_oper = false;
}

+static int qca8k_connect_tag_protocol(struct dsa_switch *ds,
+ enum dsa_tag_protocol proto)
+{
+ struct qca8k_priv *qca8k_priv = ds->priv;
+
+ switch (proto) {
+ case DSA_TAG_PROTO_QCA:
+ struct tag_qca_priv *priv;
+
+ priv = ds->tagger_data;
+
+ mutex_init(&qca8k_priv->mdio_hdr_data.mutex);
+ init_completion(&qca8k_priv->mdio_hdr_data.rw_done);
+
+ priv->rw_reg_ack_handler = qca8k_rw_reg_ack_handler;
+
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+
+ return 0;
+}
+
static const struct dsa_switch_ops qca8k_switch_ops = {
.get_tag_protocol = qca8k_get_tag_protocol,
.setup = qca8k_setup,
@@ -2431,6 +2617,7 @@ static const struct dsa_switch_ops qca8k_switch_ops = {
.port_lag_join = qca8k_port_lag_join,
.port_lag_leave = qca8k_port_lag_leave,
.master_state_change = qca8k_master_change,
+ .connect_tag_protocol = qca8k_connect_tag_protocol,
};

static int qca8k_read_switch_id(struct qca8k_priv *priv)
diff --git a/drivers/net/dsa/qca8k.h b/drivers/net/dsa/qca8k.h
index fb98536bf3e8..307c56466082 100644
--- a/drivers/net/dsa/qca8k.h
+++ b/drivers/net/dsa/qca8k.h
@@ -11,6 +11,9 @@
#include <linux/delay.h>
#include <linux/regmap.h>
#include <linux/gpio.h>
+#include <linux/dsa/tag_qca.h>
+
+#define QCA8K_ETHERNET_TIMEOUT 100

#define QCA8K_NUM_PORTS 7
#define QCA8K_NUM_CPU_PORTS 2
@@ -328,6 +331,14 @@ enum {
QCA8K_CPU_PORT6,
};

+struct qca8k_mdio_hdr_data {
+ struct completion rw_done;
+ struct mutex mutex; /* Enforce one mdio read/write at time */
+ bool ack;
+ u32 seq;
+ u32 data[4];
+};
+
struct qca8k_ports_config {
bool sgmii_rx_clk_falling_edge;
bool sgmii_tx_clk_falling_edge;
@@ -354,6 +365,7 @@ struct qca8k_priv {
struct dsa_switch_ops ops;
struct gpio_desc *reset_gpio;
unsigned int port_mtu[QCA8K_NUM_PORTS];
+ struct qca8k_mdio_hdr_data mdio_hdr_data;
};

struct qca8k_mib_desc {
diff --git a/include/linux/dsa/tag_qca.h b/include/linux/dsa/tag_qca.h
index f3369b939107..203e72dad9bb 100644
--- a/include/linux/dsa/tag_qca.h
+++ b/include/linux/dsa/tag_qca.h
@@ -56,7 +56,7 @@ struct mdio_ethhdr {
u32 command; /* command bit 31:0 */
u32 seq; /* seq 63:32 */
u32 mdio_data; /* first 4byte mdio */
- u16 hdr; /* qca hdr */
+ __be16 hdr; /* qca hdr */
} __packed;

enum mdio_cmd {
--
2.32.0