[PATCH net v2 3/5] net: dsa: vsc73xx: check busy flag in MDIO operations

Pawel Dembicki
2024-08-05T21:11:20Z

The VSC73xx has a busy flag used during MDIO operations. It is raised
when MDIO read/write operations are in progress. Without it, PHYs are
misconfigured and bus operations do not work as expected.

Fixes: 05bd97fc559d ("net: dsa: Add Vitesse VSC73xx DSA router driver")
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>

---
v2:
- used defines from patch moved to net-next

This patch came from net-next series[0].
Changes since net-next:
- removed mutex
- used method poll.h to poll busy value in 'vsc73xx_mdio_busy_check'
- use 'vsc73xx_mdio_busy_check' for control if mdio is ready

[0] https://patchwork.kernel.org/project/netdevbpf/patch/20240729210615.279952-6-paweldembicki@gmail.com/
---
drivers/net/dsa/vitesse-vsc73xx-core.c | 40 ++++++++++++++++++++++++--
1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/drivers/net/dsa/vitesse-vsc73xx-core.c b/drivers/net/dsa/vitesse-vsc73xx-core.c
index 4b300c293dec..a9378e0512d8 100644
--- a/drivers/net/dsa/vitesse-vsc73xx-core.c
+++ b/drivers/net/dsa/vitesse-vsc73xx-core.c
@@ -40,6 +40,10 @@
#define VSC73XX_BLOCK_ARBITER 0x5 /* Only subblock 0 */
#define VSC73XX_BLOCK_SYSTEM 0x7 /* Only subblock 0 */

+/* MII Block subblock */
+#define VSC73XX_BLOCK_MII_INTERNAL 0x0 /* Internal MDIO subblock */
+#define VSC73XX_BLOCK_MII_EXTERNAL 0x1 /* External MDIO subblock */
+
#define CPU_PORT 6 /* CPU port */

/* MAC Block registers */
@@ -225,6 +229,8 @@
#define VSC73XX_MII_CMD 0x1
#define VSC73XX_MII_DATA 0x2

+#define VSC73XX_MII_STAT_BUSY BIT(3)
+
/* Arbiter block 5 registers */
#define VSC73XX_ARBEMPTY 0x0c
#define VSC73XX_ARBDISC 0x0e
@@ -299,6 +305,7 @@
#define IS_739X(a) (IS_7395(a) || IS_7398(a))

#define VSC73XX_POLL_SLEEP_US 1000
+#define VSC73XX_MDIO_POLL_SLEEP_US 5
#define VSC73XX_POLL_TIMEOUT_US 10000

struct vsc73xx_counter {
@@ -527,6 +534,22 @@ static int vsc73xx_detect(struct vsc73xx *vsc)
return 0;
}

+static int vsc73xx_mdio_busy_check(struct vsc73xx *vsc)
+{
+ int ret, err;
+ u32 val;
+
+ ret = read_poll_timeout(vsc73xx_read, err,
+ err < 0 || !(val & VSC73XX_MII_STAT_BUSY),
+ VSC73XX_MDIO_POLL_SLEEP_US,
+ VSC73XX_POLL_TIMEOUT_US, false, vsc,
+ VSC73XX_BLOCK_MII, VSC73XX_BLOCK_MII_INTERNAL,
+ VSC73XX_MII_STAT, &val);
+ if (ret)
+ return ret;
+ return err;
+}
+
static int vsc73xx_phy_read(struct dsa_switch *ds, int phy, int regnum)
{
struct vsc73xx *vsc = ds->priv;
@@ -534,13 +557,22 @@ static int vsc73xx_phy_read(struct dsa_switch *ds, int phy, int regnum)
u32 val;
int ret;

+ ret = vsc73xx_mdio_busy_check(vsc);
+ if (ret)
+ return ret;
+
/* Setting bit 26 means "read" */
cmd = BIT(26) | (phy << 21) | (regnum << 16);
ret = vsc73xx_write(vsc, VSC73XX_BLOCK_MII, 0, 1, cmd);
if (ret)
return ret;
- msleep(2);
+
+ ret = vsc73xx_mdio_busy_check(vsc);
+ if (ret)
+ return ret;
+
ret = vsc73xx_read(vsc, VSC73XX_BLOCK_MII, 0, 2, &val);
+
if (ret)
return ret;
if (val & BIT(16)) {
@@ -561,7 +593,11 @@ static int vsc73xx_phy_write(struct dsa_switch *ds, int phy, int regnum,
{
struct vsc73xx *vsc = ds->priv;
u32 cmd;
- int ret;
+ int ret = 0;
+
+ ret = vsc73xx_mdio_busy_check(vsc);
+ if (ret)
+ return ret;

/* It was found through tedious experiments that this router
* chip really hates to have it's PHYs reset. They
--
2.34.1