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sfc_ef100: read Design Parameters at probe time
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Several parts of the EF100 architecture are parameterised (to allow
 varying capabilities on FPGAs according to resource constraints), and
 these parameters are exposed to the driver through a TLV-encoded
 region of the BAR.
For the most part we either don't care about these values at all or
 just need to sanity-check them against the driver's assumptions, but
 there are a number of TSO limits which we record so that we will be
 able to check against them in the TX path when handling GSO skbs.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Edward Cree authored and David S. Miller committed Aug 4, 2020
1 parent 4496363 commit adcfc34
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216 changes: 216 additions & 0 deletions drivers/net/ethernet/sfc/ef100_nic.c
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Original file line number Diff line number Diff line change
Expand Up @@ -515,6 +515,208 @@ static int compare_versions(const char *a, const char *b)
return a_patch - b_patch;
}

enum ef100_tlv_state_machine {
EF100_TLV_TYPE,
EF100_TLV_TYPE_CONT,
EF100_TLV_LENGTH,
EF100_TLV_VALUE
};

struct ef100_tlv_state {
enum ef100_tlv_state_machine state;
u64 value;
u32 value_offset;
u16 type;
u8 len;
};

static int ef100_tlv_feed(struct ef100_tlv_state *state, u8 byte)
{
switch (state->state) {
case EF100_TLV_TYPE:
state->type = byte & 0x7f;
state->state = (byte & 0x80) ? EF100_TLV_TYPE_CONT
: EF100_TLV_LENGTH;
/* Clear ready to read in a new entry */
state->value = 0;
state->value_offset = 0;
return 0;
case EF100_TLV_TYPE_CONT:
state->type |= byte << 7;
state->state = EF100_TLV_LENGTH;
return 0;
case EF100_TLV_LENGTH:
state->len = byte;
/* We only handle TLVs that fit in a u64 */
if (state->len > sizeof(state->value))
return -EOPNOTSUPP;
/* len may be zero, implying a value of zero */
state->state = state->len ? EF100_TLV_VALUE : EF100_TLV_TYPE;
return 0;
case EF100_TLV_VALUE:
state->value |= ((u64)byte) << (state->value_offset * 8);
state->value_offset++;
if (state->value_offset >= state->len)
state->state = EF100_TLV_TYPE;
return 0;
default: /* state machine error, can't happen */
WARN_ON_ONCE(1);
return -EIO;
}
}

static int ef100_process_design_param(struct efx_nic *efx,
const struct ef100_tlv_state *reader)
{
struct ef100_nic_data *nic_data = efx->nic_data;

switch (reader->type) {
case ESE_EF100_DP_GZ_PAD: /* padding, skip it */
return 0;
case ESE_EF100_DP_GZ_PARTIAL_TSTAMP_SUB_NANO_BITS:
/* Driver doesn't support timestamping yet, so we don't care */
return 0;
case ESE_EF100_DP_GZ_EVQ_UNSOL_CREDIT_SEQ_BITS:
/* Driver doesn't support unsolicited-event credits yet, so
* we don't care
*/
return 0;
case ESE_EF100_DP_GZ_NMMU_GROUP_SIZE:
/* Driver doesn't manage the NMMU (so we don't care) */
return 0;
case ESE_EF100_DP_GZ_RX_L4_CSUM_PROTOCOLS:
/* Driver uses CHECKSUM_COMPLETE, so we don't care about
* protocol checksum validation
*/
return 0;
case ESE_EF100_DP_GZ_TSO_MAX_HDR_LEN:
nic_data->tso_max_hdr_len = min_t(u64, reader->value, 0xffff);
return 0;
case ESE_EF100_DP_GZ_TSO_MAX_HDR_NUM_SEGS:
/* We always put HDR_NUM_SEGS=1 in our TSO descriptors */
if (!reader->value) {
netif_err(efx, probe, efx->net_dev,
"TSO_MAX_HDR_NUM_SEGS < 1\n");
return -EOPNOTSUPP;
}
return 0;
case ESE_EF100_DP_GZ_RXQ_SIZE_GRANULARITY:
case ESE_EF100_DP_GZ_TXQ_SIZE_GRANULARITY:
/* Our TXQ and RXQ sizes are always power-of-two and thus divisible by
* EFX_MIN_DMAQ_SIZE, so we just need to check that
* EFX_MIN_DMAQ_SIZE is divisible by GRANULARITY.
* This is very unlikely to fail.
*/
if (EFX_MIN_DMAQ_SIZE % reader->value) {
netif_err(efx, probe, efx->net_dev,
"%s size granularity is %llu, can't guarantee safety\n",
reader->type == ESE_EF100_DP_GZ_RXQ_SIZE_GRANULARITY ? "RXQ" : "TXQ",
reader->value);
return -EOPNOTSUPP;
}
return 0;
case ESE_EF100_DP_GZ_TSO_MAX_PAYLOAD_LEN:
nic_data->tso_max_payload_len = min_t(u64, reader->value, GSO_MAX_SIZE);
efx->net_dev->gso_max_size = nic_data->tso_max_payload_len;
return 0;
case ESE_EF100_DP_GZ_TSO_MAX_PAYLOAD_NUM_SEGS:
nic_data->tso_max_payload_num_segs = min_t(u64, reader->value, 0xffff);
efx->net_dev->gso_max_segs = nic_data->tso_max_payload_num_segs;
return 0;
case ESE_EF100_DP_GZ_TSO_MAX_NUM_FRAMES:
nic_data->tso_max_frames = min_t(u64, reader->value, 0xffff);
return 0;
case ESE_EF100_DP_GZ_COMPAT:
if (reader->value) {
netif_err(efx, probe, efx->net_dev,
"DP_COMPAT has unknown bits %#llx, driver not compatible with this hw\n",
reader->value);
return -EOPNOTSUPP;
}
return 0;
case ESE_EF100_DP_GZ_MEM2MEM_MAX_LEN:
/* Driver doesn't use mem2mem transfers */
return 0;
case ESE_EF100_DP_GZ_EVQ_TIMER_TICK_NANOS:
/* Driver doesn't currently use EVQ_TIMER */
return 0;
case ESE_EF100_DP_GZ_NMMU_PAGE_SIZES:
/* Driver doesn't manage the NMMU (so we don't care) */
return 0;
case ESE_EF100_DP_GZ_VI_STRIDES:
/* We never try to set the VI stride, and we don't rely on
* being able to find VIs past VI 0 until after we've learned
* the current stride from MC_CMD_GET_CAPABILITIES.
* So the value of this shouldn't matter.
*/
if (reader->value != ESE_EF100_DP_GZ_VI_STRIDES_DEFAULT)
netif_dbg(efx, probe, efx->net_dev,
"NIC has other than default VI_STRIDES (mask "
"%#llx), early probing might use wrong one\n",
reader->value);
return 0;
case ESE_EF100_DP_GZ_RX_MAX_RUNT:
/* Driver doesn't look at L2_STATUS:LEN_ERR bit, so we don't
* care whether it indicates runt or overlength for any given
* packet, so we don't care about this parameter.
*/
return 0;
default:
/* Host interface says "Drivers should ignore design parameters
* that they do not recognise."
*/
netif_dbg(efx, probe, efx->net_dev,
"Ignoring unrecognised design parameter %u\n",
reader->type);
return 0;
}
}

static int ef100_check_design_params(struct efx_nic *efx)
{
struct ef100_tlv_state reader = {};
u32 total_len, offset = 0;
efx_dword_t reg;
int rc = 0, i;
u32 data;

efx_readd(efx, &reg, ER_GZ_PARAMS_TLV_LEN);
total_len = EFX_DWORD_FIELD(reg, EFX_DWORD_0);
netif_dbg(efx, probe, efx->net_dev, "%u bytes of design parameters\n",
total_len);
while (offset < total_len) {
efx_readd(efx, &reg, ER_GZ_PARAMS_TLV + offset);
data = EFX_DWORD_FIELD(reg, EFX_DWORD_0);
for (i = 0; i < sizeof(data); i++) {
rc = ef100_tlv_feed(&reader, data);
/* Got a complete value? */
if (!rc && reader.state == EF100_TLV_TYPE)
rc = ef100_process_design_param(efx, &reader);
if (rc)
goto out;
data >>= 8;
offset++;
}
}
/* Check we didn't end halfway through a TLV entry, which could either
* mean that the TLV stream is truncated or just that it's corrupted
* and our state machine is out of sync.
*/
if (reader.state != EF100_TLV_TYPE) {
if (reader.state == EF100_TLV_TYPE_CONT)
netif_err(efx, probe, efx->net_dev,
"truncated design parameter (incomplete type %u)\n",
reader.type);
else
netif_err(efx, probe, efx->net_dev,
"truncated design parameter %u\n",
reader.type);
rc = -EIO;
}
out:
return rc;
}

/* NIC probe and remove
*/
static int ef100_probe_main(struct efx_nic *efx)
Expand All @@ -536,6 +738,20 @@ static int ef100_probe_main(struct efx_nic *efx)
net_dev->features |= efx->type->offload_features;
net_dev->hw_features |= efx->type->offload_features;

/* Populate design-parameter defaults */
nic_data->tso_max_hdr_len = ESE_EF100_DP_GZ_TSO_MAX_HDR_LEN_DEFAULT;
nic_data->tso_max_frames = ESE_EF100_DP_GZ_TSO_MAX_NUM_FRAMES_DEFAULT;
nic_data->tso_max_payload_num_segs = ESE_EF100_DP_GZ_TSO_MAX_PAYLOAD_NUM_SEGS_DEFAULT;
nic_data->tso_max_payload_len = ESE_EF100_DP_GZ_TSO_MAX_PAYLOAD_LEN_DEFAULT;
net_dev->gso_max_segs = ESE_EF100_DP_GZ_TSO_MAX_HDR_NUM_SEGS_DEFAULT;
/* Read design parameters */
rc = ef100_check_design_params(efx);
if (rc) {
netif_err(efx, probe, efx->net_dev,
"Unsupported design parameters\n");
goto fail;
}

/* we assume later that we can copy from this buffer in dwords */
BUILD_BUG_ON(MCDI_CTL_SDU_LEN_MAX_V2 % 4);

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4 changes: 4 additions & 0 deletions drivers/net/ethernet/sfc/ef100_nic.h
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,10 @@ struct ef100_nic_data {
u16 warm_boot_count;
u8 port_id[ETH_ALEN];
DECLARE_BITMAP(evq_phases, EFX_MAX_CHANNELS);
u16 tso_max_hdr_len;
u16 tso_max_payload_num_segs;
u16 tso_max_frames;
unsigned int tso_max_payload_len;
};

#define efx_ef100_has_cap(caps, flag) \
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