net: mscc: ocelot: add ops for decoding watermark threshold and occupancy

We'll need to read back the watermark thresholds and occupancy from
hardware (for devlink-sb integration), not only to write them as we did
so far in ocelot_port_set_maxlen. So introduce 2 new functions in struct
ocelot_ops, similar to wm_enc, and implement them for the 3 supported
mscc_ocelot switches.

Remove the INUSE and MAXUSE unpacking helpers for the QSYS_RES_STAT
register, because that doesn't scale with the number of switches that
mscc_ocelot supports now. They have different bit widths for the
watermarks, and we need function pointers to abstract that difference
away.

Signed-off-by: Vladimir Oltean <[e-mail]>
Reviewed-by: Florian Fainelli <[e-mail]>
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/dsa/ocelot/felix_vsc9959.c

···
 	return value;
 }
 
+static u16 vsc9959_wm_dec(u16 wm)
+{
+	WARN_ON(wm & ~GENMASK(8, 0));
+
+	if (wm & BIT(8))
+		return (wm & GENMASK(7, 0)) * 16;
+
+	return wm;
+}
+
+static void vsc9959_wm_stat(u32 val, u32 *inuse, u32 *maxuse)
+{
+	*inuse = (val & GENMASK(23, 12)) >> 12;
+	*maxuse = val & GENMASK(11, 0);
+}
+
 static const struct ocelot_ops vsc9959_ops = {
 	.reset			= vsc9959_reset,
 	.wm_enc			= vsc9959_wm_enc,
+	.wm_dec			= vsc9959_wm_dec,
+	.wm_stat		= vsc9959_wm_stat,
 	.port_to_netdev		= felix_port_to_netdev,
 	.netdev_to_port		= felix_netdev_to_port,
 };

drivers/net/dsa/ocelot/seville_vsc9953.c

···
 	return value;
 }
 
+static u16 vsc9953_wm_dec(u16 wm)
+{
+	WARN_ON(wm & ~GENMASK(9, 0));
+
+	if (wm & BIT(9))
+		return (wm & GENMASK(8, 0)) * 16;
+
+	return wm;
+}
+
+static void vsc9953_wm_stat(u32 val, u32 *inuse, u32 *maxuse)
+{
+	*inuse = (val & GENMASK(25, 13)) >> 13;
+	*maxuse = val & GENMASK(12, 0);
+}
+
 static const struct ocelot_ops vsc9953_ops = {
 	.reset			= vsc9953_reset,
 	.wm_enc			= vsc9953_wm_enc,
+	.wm_dec			= vsc9953_wm_dec,
+	.wm_stat		= vsc9953_wm_stat,
 	.port_to_netdev		= felix_port_to_netdev,
 	.netdev_to_port		= felix_netdev_to_port,
 };

drivers/net/ethernet/mscc/ocelot_vsc7514.c

···
 	return value;
 }
 
+static u16 ocelot_wm_dec(u16 wm)
+{
+	if (wm & BIT(8))
+		return (wm & GENMASK(7, 0)) * 16;
+
+	return wm;
+}
+
+static void ocelot_wm_stat(u32 val, u32 *inuse, u32 *maxuse)
+{
+	*inuse = (val & GENMASK(23, 12)) >> 12;
+	*maxuse = val & GENMASK(11, 0);
+}
+
 static const struct ocelot_ops ocelot_ops = {
 	.reset			= ocelot_reset,
 	.wm_enc			= ocelot_wm_enc,
+	.wm_dec			= ocelot_wm_dec,
+	.wm_stat		= ocelot_wm_stat,
 	.port_to_netdev		= ocelot_port_to_netdev,
 	.netdev_to_port		= ocelot_netdev_to_port,
 };

include/soc/mscc/ocelot.h

···
 	int (*netdev_to_port)(struct net_device *dev);
 	int (*reset)(struct ocelot *ocelot);
 	u16 (*wm_enc)(u16 value);
+	u16 (*wm_dec)(u16 value);
+	void (*wm_stat)(u32 val, u32 *inuse, u32 *maxuse);
 };
 
 struct ocelot_vcap_block {

include/soc/mscc/ocelot_qsys.h

···
 
 #define QSYS_RES_STAT_GSZ                                 0x8
 
-#define QSYS_RES_STAT_INUSE(x)                            (((x) << 12) & GENMASK(23, 12))
-#define QSYS_RES_STAT_INUSE_M                             GENMASK(23, 12)
-#define QSYS_RES_STAT_INUSE_X(x)                          (((x) & GENMASK(23, 12)) >> 12)
-#define QSYS_RES_STAT_MAXUSE(x)                           ((x) & GENMASK(11, 0))
-#define QSYS_RES_STAT_MAXUSE_M                            GENMASK(11, 0)
-
 #define QSYS_MMGT_EQ_CTRL_FP_FREE_CNT(x)                  ((x) & GENMASK(15, 0))
 #define QSYS_MMGT_EQ_CTRL_FP_FREE_CNT_M                   GENMASK(15, 0)