diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/net/phy/micrel.c | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c index d0429dc8f561..74fd6ff32c6c 100644 --- a/drivers/net/phy/micrel.c +++ b/drivers/net/phy/micrel.c @@ -2173,6 +2173,136 @@ static void kszphy_get_phy_stats(struct phy_device *phydev, stats->rx_errors = priv->phy_stats.rx_err_pkt_cnt; } +/* Base register for Signal Quality Indicator (SQI) - Channel A + * + * MMD Address: MDIO_MMD_PMAPMD (0x01) + * Register: 0xAC (Channel A) + * Each channel (pair) has its own register: + * Channel A: 0xAC + * Channel B: 0xAD + * Channel C: 0xAE + * Channel D: 0xAF + */ +#define KSZ9477_MMD_SIGNAL_QUALITY_CHAN_A 0xac + +/* SQI field mask for bits [14:8] + * + * SQI indicates relative quality of the signal. + * A lower value indicates better signal quality. + */ +#define KSZ9477_MMD_SQI_MASK GENMASK(14, 8) + +#define KSZ9477_MAX_CHANNELS 4 +#define KSZ9477_SQI_MAX 7 + +/* Number of SQI samples to average for a stable result. + * + * Reference: KSZ9477S Datasheet DS00002392C, Section 4.1.11 (page 26) + * For noisy environments, a minimum of 30–50 readings is recommended. + */ +#define KSZ9477_SQI_SAMPLE_COUNT 40 + +/* The hardware SQI register provides a raw value from 0-127, where a lower + * value indicates better signal quality. However, empirical testing has + * shown that only the 0-7 range is relevant for a functional link. A raw + * value of 8 or higher was measured directly before link drop. This aligns + * with the OPEN Alliance recommendation that SQI=0 should represent the + * pre-failure state. + * + * This table provides a non-linear mapping from the useful raw hardware + * values (0-7) to the standard 0-7 SQI scale, where higher is better. + */ +static const u8 ksz_sqi_mapping[] = { + 7, /* raw 0 -> SQI 7 */ + 7, /* raw 1 -> SQI 7 */ + 6, /* raw 2 -> SQI 6 */ + 5, /* raw 3 -> SQI 5 */ + 4, /* raw 4 -> SQI 4 */ + 3, /* raw 5 -> SQI 3 */ + 2, /* raw 6 -> SQI 2 */ + 1, /* raw 7 -> SQI 1 */ +}; + +/** + * kszphy_get_sqi - Read, average, and map Signal Quality Index (SQI) + * @phydev: the PHY device + * + * This function reads and processes the raw Signal Quality Index from the + * PHY. Based on empirical testing, a raw value of 8 or higher indicates a + * pre-failure state and is mapped to SQI 0. Raw values from 0-7 are + * mapped to the standard 0-7 SQI scale via a lookup table. + * + * Return: SQI value (0–7), or a negative errno on failure. + */ +static int kszphy_get_sqi(struct phy_device *phydev) +{ + int sum[KSZ9477_MAX_CHANNELS] = { 0 }; + int worst_sqi = KSZ9477_SQI_MAX; + int i, val, raw_sqi, ch; + u8 channels; + + /* Determine applicable channels based on link speed */ + if (phydev->speed == SPEED_1000) + channels = 4; + else if (phydev->speed == SPEED_100) + channels = 1; + else + return -EOPNOTSUPP; + + /* Sample and accumulate SQI readings for each pair (currently only one). + * + * Reference: KSZ9477S Datasheet DS00002392C, Section 4.1.11 (page 26) + * - The SQI register is updated every 2 µs. + * - Values may fluctuate significantly, even in low-noise environments. + * - For reliable estimation, average a minimum of 30–50 samples + * (recommended for noisy environments) + * - In noisy environments, individual readings are highly unreliable. + * + * We use 40 samples per pair with a delay of 3 µs between each + * read to ensure new values are captured (2 µs update interval). + */ + for (i = 0; i < KSZ9477_SQI_SAMPLE_COUNT; i++) { + for (ch = 0; ch < channels; ch++) { + val = phy_read_mmd(phydev, MDIO_MMD_PMAPMD, + KSZ9477_MMD_SIGNAL_QUALITY_CHAN_A + ch); + if (val < 0) + return val; + + raw_sqi = FIELD_GET(KSZ9477_MMD_SQI_MASK, val); + sum[ch] += raw_sqi; + + /* We communicate with the PHY via MDIO via SPI or + * I2C, which is relatively slow. At least slower than + * the update interval of the SQI register. + * So, we can skip the delay between reads. + */ + } + } + + /* Calculate average for each channel and find the worst SQI */ + for (ch = 0; ch < channels; ch++) { + int avg_raw_sqi = sum[ch] / KSZ9477_SQI_SAMPLE_COUNT; + int mapped_sqi; + + /* Handle the pre-fail/failed state first. */ + if (avg_raw_sqi >= ARRAY_SIZE(ksz_sqi_mapping)) + mapped_sqi = 0; + else + /* Use the lookup table for the good signal range. */ + mapped_sqi = ksz_sqi_mapping[avg_raw_sqi]; + + if (mapped_sqi < worst_sqi) + worst_sqi = mapped_sqi; + } + + return worst_sqi; +} + +static int kszphy_get_sqi_max(struct phy_device *phydev) +{ + return KSZ9477_SQI_MAX; +} + static void kszphy_enable_clk(struct phy_device *phydev) { struct kszphy_priv *priv = phydev->priv; @@ -5801,6 +5931,8 @@ static struct phy_driver ksphy_driver[] = { .update_stats = kszphy_update_stats, .cable_test_start = ksz9x31_cable_test_start, .cable_test_get_status = ksz9x31_cable_test_get_status, + .get_sqi = kszphy_get_sqi, + .get_sqi_max = kszphy_get_sqi_max, } }; module_phy_driver(ksphy_driver); |