[RFC PATCH 01/10] net: mscc: ocelot: auto-detect packet buffer size and number of frame references

Vladimir Oltean
2020-10-13T13:49:17Z

Instead of reading these values from the reference manual and writing
them down into the driver, it appears that the hardware gives us the
option of detecting them dynamically.

The number of frame references corresponds to what the reference manual
notes, however it seems that the frame buffers are reported as less than
the books would indicate. On VSC9959 (Felix), the books say it should
have 128KB of packet buffer, but the registers indicate only 103872 bytes.
Interesting...

Not having anything better to do with these values at the moment* (this
will change soon), let's just print them.

*The frame buffer size is, in fact, used to calculate the tail dropping
watermarks.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
drivers/net/dsa/ocelot/felix.c | 1 -
drivers/net/dsa/ocelot/felix.h | 1 -
drivers/net/dsa/ocelot/felix_vsc9959.c | 1 -
drivers/net/dsa/ocelot/seville_vsc9953.c | 1 -
drivers/net/ethernet/mscc/ocelot.c | 22 +++++++++++++++++++++-
drivers/net/ethernet/mscc/ocelot_vsc7514.c | 1 -
include/soc/mscc/ocelot.h | 3 ++-
include/soc/mscc/ocelot_qsys.h | 3 +++
8 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/drivers/net/dsa/ocelot/felix.c b/drivers/net/dsa/ocelot/felix.c
index f791860d495f..29ccc3315863 100644
--- a/drivers/net/dsa/ocelot/felix.c
+++ b/drivers/net/dsa/ocelot/felix.c
@@ -432,7 +432,6 @@ static int felix_init_structs(struct felix *felix, int num_phys_ports)
ocelot->map = felix->info->map;
ocelot->stats_layout = felix->info->stats_layout;
ocelot->num_stats = felix->info->num_stats;
- ocelot->shared_queue_sz = felix->info->shared_queue_sz;
ocelot->num_mact_rows = felix->info->num_mact_rows;
ocelot->vcap = felix->info->vcap;
ocelot->ops = felix->info->ops;
diff --git a/drivers/net/dsa/ocelot/felix.h b/drivers/net/dsa/ocelot/felix.h
index 4c717324ac2f..5434fe278d2c 100644
--- a/drivers/net/dsa/ocelot/felix.h
+++ b/drivers/net/dsa/ocelot/felix.h
@@ -15,7 +15,6 @@ struct felix_info {
const struct reg_field *regfields;
const u32 *const *map;
const struct ocelot_ops *ops;
- int shared_queue_sz;
int num_mact_rows;
const struct ocelot_stat_layout *stats_layout;
unsigned int num_stats;
diff --git a/drivers/net/dsa/ocelot/felix_vsc9959.c b/drivers/net/dsa/ocelot/felix_vsc9959.c
index 3e925b8d5306..a2d5a9a8baf1 100644
--- a/drivers/net/dsa/ocelot/felix_vsc9959.c
+++ b/drivers/net/dsa/ocelot/felix_vsc9959.c
@@ -1356,7 +1356,6 @@ static const struct felix_info felix_info_vsc9959 = {
.stats_layout = vsc9959_stats_layout,
.num_stats = ARRAY_SIZE(vsc9959_stats_layout),
.vcap = vsc9959_vcap_props,
- .shared_queue_sz = 128 * 1024,
.num_mact_rows = 2048,
.num_ports = 6,
.num_tx_queues = FELIX_NUM_TC,
diff --git a/drivers/net/dsa/ocelot/seville_vsc9953.c b/drivers/net/dsa/ocelot/seville_vsc9953.c
index 76576cf0ba8a..dbf2bb951761 100644
--- a/drivers/net/dsa/ocelot/seville_vsc9953.c
+++ b/drivers/net/dsa/ocelot/seville_vsc9953.c
@@ -1181,7 +1181,6 @@ static const struct felix_info seville_info_vsc9953 = {
.stats_layout = vsc9953_stats_layout,
.num_stats = ARRAY_SIZE(vsc9953_stats_layout),
.vcap = vsc9953_vcap_props,
- .shared_queue_sz = 2048 * 1024,
.num_mact_rows = 2048,
.num_ports = 10,
.mdio_bus_alloc = vsc9953_mdio_bus_alloc,
diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c
index fcbb3165ae7f..fc6fe5022719 100644
--- a/drivers/net/ethernet/mscc/ocelot.c
+++ b/drivers/net/ethernet/mscc/ocelot.c
@@ -1305,7 +1305,7 @@ void ocelot_port_set_maxlen(struct ocelot *ocelot, int port, size_t sdu)
pause_stop);

/* Tail dropping watermarks */
- atop_tot = (ocelot->shared_queue_sz - 9 * maxlen) /
+ atop_tot = (ocelot->packet_buffer_size - 9 * maxlen) /
OCELOT_BUFFER_CELL_SZ;
atop = (9 * maxlen) / OCELOT_BUFFER_CELL_SZ;
ocelot_write_rix(ocelot, ocelot->ops->wm_enc(atop), SYS_ATOP, port);
@@ -1418,6 +1418,24 @@ static void ocelot_cpu_port_init(struct ocelot *ocelot)
ANA_PORT_VLAN_CFG, cpu);
}

+static void ocelot_detect_features(struct ocelot *ocelot)
+{
+ int mmgt, eq_ctrl;
+
+ /* SYS:MMGT:MMGT:FREECNT holds the number of 192-byte
+ * free memory words.
+ */
+ mmgt = ocelot_read(ocelot, SYS_MMGT);
+ ocelot->packet_buffer_size = 192 * SYS_MMGT_FREECNT(mmgt);
+
+ eq_ctrl = ocelot_read(ocelot, QSYS_EQ_CTRL);
+ ocelot->num_frame_refs = QSYS_MMGT_EQ_CTRL_FP_FREE_CNT(eq_ctrl);
+
+ dev_info(ocelot->dev,
+ "Detected %d bytes of packet buffer and %d frame references\n",
+ ocelot->packet_buffer_size, ocelot->num_frame_refs);
+}
+
int ocelot_init(struct ocelot *ocelot)
{
char queue_name[32];
@@ -1452,6 +1470,8 @@ int ocelot_init(struct ocelot *ocelot)
if (!ocelot->stats_queue)
return -ENOMEM;

+ ocelot_detect_features(ocelot);
+
INIT_LIST_HEAD(&ocelot->multicast);
ocelot_mact_init(ocelot);
ocelot_vlan_init(ocelot);
diff --git a/drivers/net/ethernet/mscc/ocelot_vsc7514.c b/drivers/net/ethernet/mscc/ocelot_vsc7514.c
index dc00772950e5..5a07f0c23f42 100644
--- a/drivers/net/ethernet/mscc/ocelot_vsc7514.c
+++ b/drivers/net/ethernet/mscc/ocelot_vsc7514.c
@@ -517,7 +517,6 @@ static int ocelot_chip_init(struct ocelot *ocelot, const struct ocelot_ops *ops)
ocelot->map = ocelot_regmap;
ocelot->stats_layout = ocelot_stats_layout;
ocelot->num_stats = ARRAY_SIZE(ocelot_stats_layout);
- ocelot->shared_queue_sz = 224 * 1024;
ocelot->num_mact_rows = 1024;
ocelot->ops = ops;

diff --git a/include/soc/mscc/ocelot.h b/include/soc/mscc/ocelot.h
index 1e9db9577441..da3e50efcf96 100644
--- a/include/soc/mscc/ocelot.h
+++ b/include/soc/mscc/ocelot.h
@@ -604,7 +604,8 @@ struct ocelot {
const struct ocelot_stat_layout *stats_layout;
unsigned int num_stats;

- int shared_queue_sz;
+ int packet_buffer_size;
+ int num_frame_refs;
int num_mact_rows;

struct net_device *hw_bridge_dev;
diff --git a/include/soc/mscc/ocelot_qsys.h b/include/soc/mscc/ocelot_qsys.h
index a814bc2017d8..b7b263a19068 100644
--- a/include/soc/mscc/ocelot_qsys.h
+++ b/include/soc/mscc/ocelot_qsys.h
@@ -77,6 +77,9 @@
#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)
+
#define QSYS_EVENTS_CORE_EV_FDC(x) (((x) << 2) & GENMASK(4, 2))
#define QSYS_EVENTS_CORE_EV_FDC_M GENMASK(4, 2)
#define QSYS_EVENTS_CORE_EV_FDC_X(x) (((x) & GENMASK(4, 2)) >> 2)
--
2.25.1