diff --git a/drivers/net/dsa/sja1105/sja1105.h b/drivers/net/dsa/sja1105/sja1105.h index 4c40f2d51a54..a358fc89a6db 100644 --- a/drivers/net/dsa/sja1105/sja1105.h +++ b/drivers/net/dsa/sja1105/sja1105.h @@ -38,10 +38,13 @@ struct sja1105_regs { u64 config; u64 sgmii; u64 rmii_pll1; + u64 ptppinst; + u64 ptppindur; u64 ptp_control; u64 ptpclkval; u64 ptpclkrate; u64 ptpclkcorp; + u64 ptpsyncts; u64 ptpschtm; u64 ptpegr_ts[SJA1105_NUM_PORTS]; u64 pad_mii_tx[SJA1105_NUM_PORTS]; @@ -214,5 +217,7 @@ size_t sja1105_vlan_lookup_entry_packing(void *buf, void *entry_ptr, enum packing_op op); size_t sja1105pqrs_mac_config_entry_packing(void *buf, void *entry_ptr, enum packing_op op); +size_t sja1105pqrs_avb_params_entry_packing(void *buf, void *entry_ptr, + enum packing_op op); #endif diff --git a/drivers/net/dsa/sja1105/sja1105_dynamic_config.c b/drivers/net/dsa/sja1105/sja1105_dynamic_config.c index 25381bd65ed7..bf9b36ff35bf 100644 --- a/drivers/net/dsa/sja1105/sja1105_dynamic_config.c +++ b/drivers/net/dsa/sja1105/sja1105_dynamic_config.c @@ -124,6 +124,9 @@ #define SJA1105ET_SIZE_GENERAL_PARAMS_DYN_CMD \ SJA1105_SIZE_DYN_CMD +#define SJA1105PQRS_SIZE_AVB_PARAMS_DYN_CMD \ + (SJA1105_SIZE_DYN_CMD + SJA1105PQRS_SIZE_AVB_PARAMS_ENTRY) + #define SJA1105_MAX_DYN_CMD_SIZE \ SJA1105PQRS_SIZE_MAC_CONFIG_DYN_CMD @@ -481,6 +484,18 @@ sja1105et_general_params_entry_packing(void *buf, void *entry_ptr, return 0; } +static void +sja1105pqrs_avb_params_cmd_packing(void *buf, struct sja1105_dyn_cmd *cmd, + enum packing_op op) +{ + u8 *p = buf + SJA1105PQRS_SIZE_AVB_PARAMS_ENTRY; + const int size = SJA1105_SIZE_DYN_CMD; + + sja1105_packing(p, &cmd->valid, 31, 31, size, op); + sja1105_packing(p, &cmd->errors, 30, 30, size, op); + sja1105_packing(p, &cmd->rdwrset, 29, 29, size, op); +} + #define OP_READ BIT(0) #define OP_WRITE BIT(1) #define OP_DEL BIT(2) @@ -610,7 +625,14 @@ struct sja1105_dynamic_table_ops sja1105pqrs_dyn_ops[BLK_IDX_MAX_DYN] = { .addr = 0x38, }, [BLK_IDX_L2_FORWARDING_PARAMS] = {0}, - [BLK_IDX_AVB_PARAMS] = {0}, + [BLK_IDX_AVB_PARAMS] = { + .entry_packing = sja1105pqrs_avb_params_entry_packing, + .cmd_packing = sja1105pqrs_avb_params_cmd_packing, + .max_entry_count = SJA1105_MAX_AVB_PARAMS_COUNT, + .access = (OP_READ | OP_WRITE), + .packed_size = SJA1105PQRS_SIZE_AVB_PARAMS_DYN_CMD, + .addr = 0x8003, + }, [BLK_IDX_GENERAL_PARAMS] = { .entry_packing = sja1105et_general_params_entry_packing, .cmd_packing = sja1105et_general_params_cmd_packing, diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c index afafe2ecf248..e0c99bb63cdf 100644 --- a/drivers/net/dsa/sja1105/sja1105_main.c +++ b/drivers/net/dsa/sja1105/sja1105_main.c @@ -479,6 +479,43 @@ static int sja1105_init_general_params(struct sja1105_private *priv) return 0; } +static int sja1105_init_avb_params(struct sja1105_private *priv) +{ + struct sja1105_avb_params_entry *avb; + struct sja1105_table *table; + + table = &priv->static_config.tables[BLK_IDX_AVB_PARAMS]; + + /* Discard previous AVB Parameters Table */ + if (table->entry_count) { + kfree(table->entries); + table->entry_count = 0; + } + + table->entries = kcalloc(SJA1105_MAX_AVB_PARAMS_COUNT, + table->ops->unpacked_entry_size, GFP_KERNEL); + if (!table->entries) + return -ENOMEM; + + table->entry_count = SJA1105_MAX_AVB_PARAMS_COUNT; + + avb = table->entries; + + /* Configure the MAC addresses for meta frames */ + avb->destmeta = SJA1105_META_DMAC; + avb->srcmeta = SJA1105_META_SMAC; + /* On P/Q/R/S, configure the direction of the PTP_CLK pin as input by + * default. This is because there might be boards with a hardware + * layout where enabling the pin as output might cause an electrical + * clash. On E/T the pin is always an output, which the board designers + * probably already knew, so even if there are going to be electrical + * issues, there's nothing we can do. + */ + avb->cas_master = false; + + return 0; +} + #define SJA1105_RATE_MBPS(speed) (((speed) * 64000) / 1000) static void sja1105_setup_policer(struct sja1105_l2_policing_entry *policing, @@ -567,6 +604,9 @@ static int sja1105_static_config_load(struct sja1105_private *priv, if (rc < 0) return rc; rc = sja1105_init_general_params(priv); + if (rc < 0) + return rc; + rc = sja1105_init_avb_params(priv); if (rc < 0) return rc; diff --git a/drivers/net/dsa/sja1105/sja1105_ptp.c b/drivers/net/dsa/sja1105/sja1105_ptp.c index a836fc38c4a4..a22f8e3fc06b 100644 --- a/drivers/net/dsa/sja1105/sja1105_ptp.c +++ b/drivers/net/dsa/sja1105/sja1105_ptp.c @@ -14,6 +14,17 @@ #define SJA1105_MAX_ADJ_PPB 32000000 #define SJA1105_SIZE_PTP_CMD 4 +/* PTPSYNCTS has no interrupt or update mechanism, because the intended + * hardware use case is for the timestamp to be collected synchronously, + * immediately after the CAS_MASTER SJA1105 switch has triggered a CASSYNC + * pulse on the PTP_CLK pin. When used as a generic extts source, it needs + * polling and a comparison with the old value. The polling interval is just + * the Nyquist rate of a canonical PPS input (e.g. from a GPS module). + * Anything of higher frequency than 1 Hz will be lost, since there is no + * timestamp FIFO. + */ +#define SJA1105_EXTTS_INTERVAL (HZ / 2) + /* This range is actually +/- SJA1105_MAX_ADJ_PPB * divided by 1000 (ppb -> ppm) and with a 16-bit * "fractional" part (actually fixed point). @@ -39,44 +50,13 @@ enum sja1105_ptp_clk_mode { PTP_SET_MODE = 0, }; +#define extts_to_data(d) \ + container_of((d), struct sja1105_ptp_data, extts_work) #define ptp_caps_to_data(d) \ container_of((d), struct sja1105_ptp_data, caps) #define ptp_data_to_sja1105(d) \ container_of((d), struct sja1105_private, ptp_data) -static int sja1105_init_avb_params(struct sja1105_private *priv, - bool on) -{ - struct sja1105_avb_params_entry *avb; - struct sja1105_table *table; - - table = &priv->static_config.tables[BLK_IDX_AVB_PARAMS]; - - /* Discard previous AVB Parameters Table */ - if (table->entry_count) { - kfree(table->entries); - table->entry_count = 0; - } - - /* Configure the reception of meta frames only if requested */ - if (!on) - return 0; - - table->entries = kcalloc(SJA1105_MAX_AVB_PARAMS_COUNT, - table->ops->unpacked_entry_size, GFP_KERNEL); - if (!table->entries) - return -ENOMEM; - - table->entry_count = SJA1105_MAX_AVB_PARAMS_COUNT; - - avb = table->entries; - - avb->destmeta = SJA1105_META_DMAC; - avb->srcmeta = SJA1105_META_SMAC; - - return 0; -} - /* Must be called only with priv->tagger_data.state bit * SJA1105_HWTS_RX_EN cleared */ @@ -86,17 +66,12 @@ static int sja1105_change_rxtstamping(struct sja1105_private *priv, struct sja1105_ptp_data *ptp_data = &priv->ptp_data; struct sja1105_general_params_entry *general_params; struct sja1105_table *table; - int rc; table = &priv->static_config.tables[BLK_IDX_GENERAL_PARAMS]; general_params = table->entries; general_params->send_meta1 = on; general_params->send_meta0 = on; - rc = sja1105_init_avb_params(priv, on); - if (rc < 0) - return rc; - /* Initialize the meta state machine to a known state */ if (priv->tagger_data.stampable_skb) { kfree_skb(priv->tagger_data.stampable_skb); @@ -206,6 +181,8 @@ void sja1105et_ptp_cmd_packing(u8 *buf, struct sja1105_ptp_cmd *cmd, sja1105_packing(buf, &valid, 31, 31, size, op); sja1105_packing(buf, &cmd->ptpstrtsch, 30, 30, size, op); sja1105_packing(buf, &cmd->ptpstopsch, 29, 29, size, op); + sja1105_packing(buf, &cmd->startptpcp, 28, 28, size, op); + sja1105_packing(buf, &cmd->stopptpcp, 27, 27, size, op); sja1105_packing(buf, &cmd->resptp, 2, 2, size, op); sja1105_packing(buf, &cmd->corrclk4ts, 1, 1, size, op); sja1105_packing(buf, &cmd->ptpclkadd, 0, 0, size, op); @@ -221,6 +198,8 @@ void sja1105pqrs_ptp_cmd_packing(u8 *buf, struct sja1105_ptp_cmd *cmd, sja1105_packing(buf, &valid, 31, 31, size, op); sja1105_packing(buf, &cmd->ptpstrtsch, 30, 30, size, op); sja1105_packing(buf, &cmd->ptpstopsch, 29, 29, size, op); + sja1105_packing(buf, &cmd->startptpcp, 28, 28, size, op); + sja1105_packing(buf, &cmd->stopptpcp, 27, 27, size, op); sja1105_packing(buf, &cmd->resptp, 3, 3, size, op); sja1105_packing(buf, &cmd->corrclk4ts, 2, 2, size, op); sja1105_packing(buf, &cmd->ptpclkadd, 0, 0, size, op); @@ -615,6 +594,227 @@ static int sja1105_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta) return rc; } +static void sja1105_ptp_extts_work(struct work_struct *work) +{ + struct delayed_work *dw = to_delayed_work(work); + struct sja1105_ptp_data *ptp_data = extts_to_data(dw); + struct sja1105_private *priv = ptp_data_to_sja1105(ptp_data); + const struct sja1105_regs *regs = priv->info->regs; + struct ptp_clock_event event; + u64 ptpsyncts = 0; + int rc; + + mutex_lock(&ptp_data->lock); + + rc = sja1105_xfer_u64(priv, SPI_READ, regs->ptpsyncts, &ptpsyncts, + NULL); + if (rc < 0) + dev_err_ratelimited(priv->ds->dev, + "Failed to read PTPSYNCTS: %d\n", rc); + + if (ptpsyncts && ptp_data->ptpsyncts != ptpsyncts) { + event.index = 0; + event.type = PTP_CLOCK_EXTTS; + event.timestamp = ns_to_ktime(sja1105_ticks_to_ns(ptpsyncts)); + ptp_clock_event(ptp_data->clock, &event); + + ptp_data->ptpsyncts = ptpsyncts; + } + + mutex_unlock(&ptp_data->lock); + + schedule_delayed_work(&ptp_data->extts_work, SJA1105_EXTTS_INTERVAL); +} + +static int sja1105_change_ptp_clk_pin_func(struct sja1105_private *priv, + enum ptp_pin_function func) +{ + struct sja1105_avb_params_entry *avb; + enum ptp_pin_function old_func; + + avb = priv->static_config.tables[BLK_IDX_AVB_PARAMS].entries; + + if (priv->info->device_id == SJA1105E_DEVICE_ID || + priv->info->device_id == SJA1105T_DEVICE_ID || + avb->cas_master) + old_func = PTP_PF_PEROUT; + else + old_func = PTP_PF_EXTTS; + + if (func == old_func) + return 0; + + avb->cas_master = (func == PTP_PF_PEROUT); + + return sja1105_dynamic_config_write(priv, BLK_IDX_AVB_PARAMS, 0, avb, + true); +} + +/* The PTP_CLK pin may be configured to toggle with a 50% duty cycle and a + * frequency f: + * + * NSEC_PER_SEC + * f = ---------------------- + * (PTPPINDUR * 8 ns) * 2 + */ +static int sja1105_per_out_enable(struct sja1105_private *priv, + struct ptp_perout_request *perout, + bool on) +{ + struct sja1105_ptp_data *ptp_data = &priv->ptp_data; + const struct sja1105_regs *regs = priv->info->regs; + struct sja1105_ptp_cmd cmd = ptp_data->cmd; + int rc; + + /* We only support one channel */ + if (perout->index != 0) + return -EOPNOTSUPP; + + /* Reject requests with unsupported flags */ + if (perout->flags) + return -EOPNOTSUPP; + + mutex_lock(&ptp_data->lock); + + rc = sja1105_change_ptp_clk_pin_func(priv, PTP_PF_PEROUT); + if (rc) + goto out; + + if (on) { + struct timespec64 pin_duration_ts = { + .tv_sec = perout->period.sec, + .tv_nsec = perout->period.nsec, + }; + struct timespec64 pin_start_ts = { + .tv_sec = perout->start.sec, + .tv_nsec = perout->start.nsec, + }; + u64 pin_duration = timespec64_to_ns(&pin_duration_ts); + u64 pin_start = timespec64_to_ns(&pin_start_ts); + u32 pin_duration32; + u64 now; + + /* ptppindur: 32 bit register which holds the interval between + * 2 edges on PTP_CLK. So check for truncation which happens + * at periods larger than around 68.7 seconds. + */ + pin_duration = ns_to_sja1105_ticks(pin_duration / 2); + if (pin_duration > U32_MAX) { + rc = -ERANGE; + goto out; + } + pin_duration32 = pin_duration; + + /* ptppins: 64 bit register which needs to hold a PTP time + * larger than the current time, otherwise the startptpcp + * command won't do anything. So advance the current time + * by a number of periods in a way that won't alter the + * phase offset. + */ + rc = __sja1105_ptp_gettimex(priv->ds, &now, NULL); + if (rc < 0) + goto out; + + pin_start = future_base_time(pin_start, pin_duration, + now + 1ull * NSEC_PER_SEC); + pin_start = ns_to_sja1105_ticks(pin_start); + + rc = sja1105_xfer_u64(priv, SPI_WRITE, regs->ptppinst, + &pin_start, NULL); + if (rc < 0) + goto out; + + rc = sja1105_xfer_u32(priv, SPI_WRITE, regs->ptppindur, + &pin_duration32, NULL); + if (rc < 0) + goto out; + } + + if (on) + cmd.startptpcp = true; + else + cmd.stopptpcp = true; + + rc = sja1105_ptp_commit(priv->ds, &cmd, SPI_WRITE); + +out: + mutex_unlock(&ptp_data->lock); + + return rc; +} + +static int sja1105_extts_enable(struct sja1105_private *priv, + struct ptp_extts_request *extts, + bool on) +{ + int rc; + + /* We only support one channel */ + if (extts->index != 0) + return -EOPNOTSUPP; + + /* Reject requests with unsupported flags */ + if (extts->flags) + return -EOPNOTSUPP; + + rc = sja1105_change_ptp_clk_pin_func(priv, PTP_PF_EXTTS); + if (rc) + return rc; + + if (on) + schedule_delayed_work(&priv->ptp_data.extts_work, + SJA1105_EXTTS_INTERVAL); + else + cancel_delayed_work_sync(&priv->ptp_data.extts_work); + + return 0; +} + +static int sja1105_ptp_enable(struct ptp_clock_info *ptp, + struct ptp_clock_request *req, int on) +{ + struct sja1105_ptp_data *ptp_data = ptp_caps_to_data(ptp); + struct sja1105_private *priv = ptp_data_to_sja1105(ptp_data); + int rc = -EOPNOTSUPP; + + if (req->type == PTP_CLK_REQ_PEROUT) + rc = sja1105_per_out_enable(priv, &req->perout, on); + else if (req->type == PTP_CLK_REQ_EXTTS) + rc = sja1105_extts_enable(priv, &req->extts, on); + + return rc; +} + +static int sja1105_ptp_verify_pin(struct ptp_clock_info *ptp, unsigned int pin, + enum ptp_pin_function func, unsigned int chan) +{ + struct sja1105_ptp_data *ptp_data = ptp_caps_to_data(ptp); + struct sja1105_private *priv = ptp_data_to_sja1105(ptp_data); + + if (chan != 0 || pin != 0) + return -1; + + switch (func) { + case PTP_PF_NONE: + case PTP_PF_PEROUT: + break; + case PTP_PF_EXTTS: + if (priv->info->device_id == SJA1105E_DEVICE_ID || + priv->info->device_id == SJA1105T_DEVICE_ID) + return -1; + break; + default: + return -1; + } + return 0; +} + +static struct ptp_pin_desc sja1105_ptp_pin = { + .name = "ptp_clk", + .index = 0, + .func = PTP_PF_NONE, +}; + int sja1105_ptp_clock_register(struct dsa_switch *ds) { struct sja1105_private *priv = ds->priv; @@ -628,8 +828,14 @@ int sja1105_ptp_clock_register(struct dsa_switch *ds) .adjtime = sja1105_ptp_adjtime, .gettimex64 = sja1105_ptp_gettimex, .settime64 = sja1105_ptp_settime, + .enable = sja1105_ptp_enable, + .verify = sja1105_ptp_verify_pin, .do_aux_work = sja1105_rxtstamp_work, .max_adj = SJA1105_MAX_ADJ_PPB, + .pin_config = &sja1105_ptp_pin, + .n_pins = 1, + .n_ext_ts = 1, + .n_per_out = 1, }; skb_queue_head_init(&ptp_data->skb_rxtstamp_queue); @@ -642,6 +848,8 @@ int sja1105_ptp_clock_register(struct dsa_switch *ds) ptp_data->cmd.corrclk4ts = true; ptp_data->cmd.ptpclkadd = PTP_SET_MODE; + INIT_DELAYED_WORK(&ptp_data->extts_work, sja1105_ptp_extts_work); + return sja1105_ptp_reset(ds); } @@ -653,6 +861,7 @@ void sja1105_ptp_clock_unregister(struct dsa_switch *ds) if (IS_ERR_OR_NULL(ptp_data->clock)) return; + cancel_delayed_work_sync(&ptp_data->extts_work); ptp_cancel_worker_sync(ptp_data->clock); skb_queue_purge(&ptp_data->skb_rxtstamp_queue); ptp_clock_unregister(ptp_data->clock); diff --git a/drivers/net/dsa/sja1105/sja1105_ptp.h b/drivers/net/dsa/sja1105/sja1105_ptp.h index 6f4a19eec709..43480b24f1f0 100644 --- a/drivers/net/dsa/sja1105/sja1105_ptp.h +++ b/drivers/net/dsa/sja1105/sja1105_ptp.h @@ -21,7 +21,36 @@ static inline s64 sja1105_ticks_to_ns(s64 ticks) return ticks * SJA1105_TICK_NS; } +/* Calculate the first base_time in the future that satisfies this + * relationship: + * + * future_base_time = base_time + N x cycle_time >= now, or + * + * now - base_time + * N >= --------------- + * cycle_time + * + * Because N is an integer, the ceiling value of the above "a / b" ratio + * is in fact precisely the floor value of "(a + b - 1) / b", which is + * easier to calculate only having integer division tools. + */ +static inline s64 future_base_time(s64 base_time, s64 cycle_time, s64 now) +{ + s64 a, b, n; + + if (base_time >= now) + return base_time; + + a = now - base_time; + b = cycle_time; + n = div_s64(a + b - 1, b); + + return base_time + n * cycle_time; +} + struct sja1105_ptp_cmd { + u64 startptpcp; /* start toggling PTP_CLK pin */ + u64 stopptpcp; /* stop toggling PTP_CLK pin */ u64 ptpstrtsch; /* start schedule */ u64 ptpstopsch; /* stop schedule */ u64 resptp; /* reset */ @@ -30,12 +59,14 @@ struct sja1105_ptp_cmd { }; struct sja1105_ptp_data { + struct delayed_work extts_work; struct sk_buff_head skb_rxtstamp_queue; struct ptp_clock_info caps; struct ptp_clock *clock; struct sja1105_ptp_cmd cmd; /* Serializes all operations on the PTP hardware clock */ struct mutex lock; + u64 ptpsyncts; }; int sja1105_ptp_clock_register(struct dsa_switch *ds); diff --git a/drivers/net/dsa/sja1105/sja1105_spi.c b/drivers/net/dsa/sja1105/sja1105_spi.c index 45da162ba268..fef2c50cd3f6 100644 --- a/drivers/net/dsa/sja1105/sja1105_spi.c +++ b/drivers/net/dsa/sja1105/sja1105_spi.c @@ -458,6 +458,8 @@ static struct sja1105_regs sja1105et_regs = { .rmii_ext_tx_clk = {0x100018, 0x10001F, 0x100026, 0x10002D, 0x100034}, .ptpegr_ts = {0xC0, 0xC2, 0xC4, 0xC6, 0xC8}, .ptpschtm = 0x12, /* Spans 0x12 to 0x13 */ + .ptppinst = 0x14, + .ptppindur = 0x16, .ptp_control = 0x17, .ptpclkval = 0x18, /* Spans 0x18 to 0x19 */ .ptpclkrate = 0x1A, @@ -491,10 +493,13 @@ static struct sja1105_regs sja1105pqrs_regs = { .qlevel = {0x604, 0x614, 0x624, 0x634, 0x644}, .ptpegr_ts = {0xC0, 0xC4, 0xC8, 0xCC, 0xD0}, .ptpschtm = 0x13, /* Spans 0x13 to 0x14 */ + .ptppinst = 0x15, + .ptppindur = 0x17, .ptp_control = 0x18, .ptpclkval = 0x19, .ptpclkrate = 0x1B, .ptpclkcorp = 0x1E, + .ptpsyncts = 0x1F, }; struct sja1105_info sja1105e_info = { diff --git a/drivers/net/dsa/sja1105/sja1105_static_config.c b/drivers/net/dsa/sja1105/sja1105_static_config.c index 63d2311817c4..bbfe034910a0 100644 --- a/drivers/net/dsa/sja1105/sja1105_static_config.c +++ b/drivers/net/dsa/sja1105/sja1105_static_config.c @@ -102,12 +102,13 @@ static size_t sja1105et_avb_params_entry_packing(void *buf, void *entry_ptr, return size; } -static size_t sja1105pqrs_avb_params_entry_packing(void *buf, void *entry_ptr, - enum packing_op op) +size_t sja1105pqrs_avb_params_entry_packing(void *buf, void *entry_ptr, + enum packing_op op) { const size_t size = SJA1105PQRS_SIZE_AVB_PARAMS_ENTRY; struct sja1105_avb_params_entry *entry = entry_ptr; + sja1105_packing(buf, &entry->cas_master, 126, 126, size, op); sja1105_packing(buf, &entry->destmeta, 125, 78, size, op); sja1105_packing(buf, &entry->srcmeta, 77, 30, size, op); return size; diff --git a/drivers/net/dsa/sja1105/sja1105_static_config.h b/drivers/net/dsa/sja1105/sja1105_static_config.h index f4a5c5c04311..8afafb6aef12 100644 --- a/drivers/net/dsa/sja1105/sja1105_static_config.h +++ b/drivers/net/dsa/sja1105/sja1105_static_config.h @@ -230,6 +230,7 @@ struct sja1105_l2_policing_entry { }; struct sja1105_avb_params_entry { + u64 cas_master; u64 destmeta; u64 srcmeta; }; diff --git a/drivers/net/dsa/sja1105/sja1105_tas.c b/drivers/net/dsa/sja1105/sja1105_tas.c index fa6750d973d7..77e547b4cd89 100644 --- a/drivers/net/dsa/sja1105/sja1105_tas.c +++ b/drivers/net/dsa/sja1105/sja1105_tas.c @@ -28,33 +28,6 @@ static s64 sja1105_delta_to_ns(s64 delta) return delta * 200; } -/* Calculate the first base_time in the future that satisfies this - * relationship: - * - * future_base_time = base_time + N x cycle_time >= now, or - * - * now - base_time - * N >= --------------- - * cycle_time - * - * Because N is an integer, the ceiling value of the above "a / b" ratio - * is in fact precisely the floor value of "(a + b - 1) / b", which is - * easier to calculate only having integer division tools. - */ -static s64 future_base_time(s64 base_time, s64 cycle_time, s64 now) -{ - s64 a, b, n; - - if (base_time >= now) - return base_time; - - a = now - base_time; - b = cycle_time; - n = div_s64(a + b - 1, b); - - return base_time + n * cycle_time; -} - static int sja1105_tas_set_runtime_params(struct sja1105_private *priv) { struct sja1105_tas_data *tas_data = &priv->tas_data;