[PATCH 6.1 041/131] phy: lynx-28g: serialize concurrent phy_set_mode_ext() calls to shared registers

Greg Kroah-Hartman
2023-10-16T08:59:29Z

From: Vladimir Oltean <vladimir.oltean@nxp.com>

[ Upstream commit 139ad1143151a07be93bf741d4ea7c89e59f89ce ]

The protocol converter configuration registers PCC8, PCCC, PCCD
(implemented by the driver), as well as others, control protocol
converters from multiple lanes (each represented as a different
struct phy). So, if there are simultaneous calls to phy_set_mode_ext()
to lanes sharing the same PCC register (either for the "old" or for the
"new" protocol), corruption of the values programmed to hardware is
possible, because lynx_28g_rmw() has no locking.

Add a spinlock in the struct lynx_28g_priv shared by all lanes, and take
the global spinlock from the phy_ops :: set_mode() implementation. There
are no other callers which modify PCC registers.

Fixes: 8f73b37cf3fb ("phy: add support for the Layerscape SerDes 28G")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/phy/freescale/phy-fsl-lynx-28g.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/drivers/phy/freescale/phy-fsl-lynx-28g.c b/drivers/phy/freescale/phy-fsl-lynx-28g.c
index d49aa59c7d812..0a8b40edc3f31 100644
--- a/drivers/phy/freescale/phy-fsl-lynx-28g.c
+++ b/drivers/phy/freescale/phy-fsl-lynx-28g.c
@@ -126,6 +126,10 @@ struct lynx_28g_lane {
struct lynx_28g_priv {
void __iomem *base;
struct device *dev;
+ /* Serialize concurrent access to registers shared between lanes,
+ * like PCCn
+ */
+ spinlock_t pcc_lock;
struct lynx_28g_pll pll[LYNX_28G_NUM_PLL];
struct lynx_28g_lane lane[LYNX_28G_NUM_LANE];

@@ -396,6 +400,8 @@ static int lynx_28g_set_mode(struct phy *phy, enum phy_mode mode, int submode)
if (powered_up)
lynx_28g_power_off(phy);

+ spin_lock(&priv->pcc_lock);
+
switch (submode) {
case PHY_INTERFACE_MODE_SGMII:
case PHY_INTERFACE_MODE_1000BASEX:
@@ -412,6 +418,8 @@ static int lynx_28g_set_mode(struct phy *phy, enum phy_mode mode, int submode)
lane->interface = submode;

out:
+ spin_unlock(&priv->pcc_lock);
+
/* Power up the lane if necessary */
if (powered_up)
lynx_28g_power_on(phy);
@@ -595,6 +603,7 @@ static int lynx_28g_probe(struct platform_device *pdev)

dev_set_drvdata(dev, priv);

+ spin_lock_init(&priv->pcc_lock);
INIT_DELAYED_WORK(&priv->cdr_check, lynx_28g_cdr_lock_check);

queue_delayed_work(system_power_efficient_wq, &priv->cdr_check,
--
2.40.1