From 1141b0ace0a556b8a9e452db8031fb2caacad50b Mon Sep 17 00:00:00 2001 From: Aaron Kling Date: Sat, 23 Aug 2025 17:27:45 -0500 Subject: [PATCH] memory: tegra186-emc: Support non-bpmp icc scaling This adds support for dynamic frequency scaling of external memory on devices with bpmp firmware that does not support bwmgr. Signed-off-by: Aaron Kling --- drivers/memory/tegra/tegra186-emc.c | 132 +++++++++++++++++++++++++++- 1 file changed, 130 insertions(+), 2 deletions(-) diff --git a/drivers/memory/tegra/tegra186-emc.c b/drivers/memory/tegra/tegra186-emc.c index d094905575cf..208f97fe4fa6 100644 --- a/drivers/memory/tegra/tegra186-emc.c +++ b/drivers/memory/tegra/tegra186-emc.c @@ -18,6 +18,17 @@ struct tegra186_emc_dvfs { unsigned long rate; }; +enum emc_rate_request_type { + EMC_RATE_DEBUG, + EMC_RATE_ICC, + EMC_RATE_TYPE_MAX, +}; + +struct emc_rate_request { + unsigned long min_rate; + unsigned long max_rate; +}; + struct tegra186_emc { struct tegra_bpmp *bpmp; struct device *dev; @@ -33,8 +44,90 @@ struct tegra186_emc { } debugfs; struct icc_provider provider; + + /* + * There are multiple sources in the EMC driver which could request + * a min/max clock rate, these rates are contained in this array. + */ + struct emc_rate_request requested_rate[EMC_RATE_TYPE_MAX]; + + /* protect shared rate-change code path */ + struct mutex rate_lock; }; +static void tegra_emc_rate_requests_init(struct tegra186_emc *emc) +{ + unsigned int i; + + for (i = 0; i < EMC_RATE_TYPE_MAX; i++) { + emc->requested_rate[i].min_rate = 0; + emc->requested_rate[i].max_rate = ULONG_MAX; + } +} + +static int emc_request_rate(struct tegra186_emc *emc, + unsigned long new_min_rate, + unsigned long new_max_rate, + enum emc_rate_request_type type) +{ + struct emc_rate_request *req = emc->requested_rate; + unsigned long min_rate = 0, max_rate = ULONG_MAX; + unsigned int i; + int err; + + /* select minimum and maximum rates among the requested rates */ + for (i = 0; i < EMC_RATE_TYPE_MAX; i++, req++) { + if (i == type) { + min_rate = max(new_min_rate, min_rate); + max_rate = min(new_max_rate, max_rate); + } else { + min_rate = max(req->min_rate, min_rate); + max_rate = min(req->max_rate, max_rate); + } + } + + if (min_rate > max_rate) { + dev_err_ratelimited(emc->dev, "%s: type %u: out of range: %lu %lu\n", + __func__, type, min_rate, max_rate); + return -ERANGE; + } + + err = clk_set_rate(emc->clk, min_rate); + if (err) + return err; + + emc->requested_rate[type].min_rate = new_min_rate; + emc->requested_rate[type].max_rate = new_max_rate; + + return 0; +} + +static int emc_set_min_rate(struct tegra186_emc *emc, unsigned long rate, + enum emc_rate_request_type type) +{ + struct emc_rate_request *req = &emc->requested_rate[type]; + int ret; + + mutex_lock(&emc->rate_lock); + ret = emc_request_rate(emc, rate, req->max_rate, type); + mutex_unlock(&emc->rate_lock); + + return ret; +} + +static int emc_set_max_rate(struct tegra186_emc *emc, unsigned long rate, + enum emc_rate_request_type type) +{ + struct emc_rate_request *req = &emc->requested_rate[type]; + int ret; + + mutex_lock(&emc->rate_lock); + ret = emc_request_rate(emc, req->min_rate, rate, type); + mutex_unlock(&emc->rate_lock); + + return ret; +} + /* * debugfs interface * @@ -107,7 +200,7 @@ static int tegra186_emc_debug_min_rate_set(void *data, u64 rate) if (!tegra186_emc_validate_rate(emc, rate)) return -EINVAL; - err = clk_set_min_rate(emc->clk, rate); + err = emc_set_min_rate(emc, rate, EMC_RATE_DEBUG); if (err < 0) return err; @@ -137,7 +230,7 @@ static int tegra186_emc_debug_max_rate_set(void *data, u64 rate) if (!tegra186_emc_validate_rate(emc, rate)) return -EINVAL; - err = clk_set_max_rate(emc->clk, rate); + err = emc_set_max_rate(emc, rate, EMC_RATE_DEBUG); if (err < 0) return err; @@ -217,6 +310,12 @@ static int tegra186_emc_get_emc_dvfs_latency(struct tegra186_emc *emc) return 0; } +static inline struct tegra186_emc * +to_tegra186_emc_provider(struct icc_provider *provider) +{ + return container_of(provider, struct tegra186_emc, provider); +} + /* * tegra_emc_icc_set_bw() - Set BW api for EMC provider * @src: ICC node for External Memory Controller (EMC) @@ -227,6 +326,33 @@ static int tegra186_emc_get_emc_dvfs_latency(struct tegra186_emc *emc) */ static int tegra_emc_icc_set_bw(struct icc_node *src, struct icc_node *dst) { + struct tegra186_emc *emc = to_tegra186_emc_provider(dst->provider); + struct tegra_mc *mc = dev_get_drvdata(emc->dev->parent); + unsigned long long peak_bw = icc_units_to_bps(dst->peak_bw); + unsigned long long avg_bw = icc_units_to_bps(dst->avg_bw); + unsigned long long rate = max(avg_bw, peak_bw); + const unsigned int ddr = 2; + int err; + + /* + * Do nothing here if bwmgr is supported in BPMP-FW. BPMP-FW sets the final + * Freq based on the passed values. + */ + if (mc->bwmgr_mrq_supported) + return 0; + + /* + * Tegra186 EMC runs on a clock rate of SDRAM bus. This means that + * EMC clock rate is twice smaller than the peak data rate because + * data is sampled on both EMC clock edges. + */ + do_div(rate, ddr); + rate = min_t(u64, rate, U32_MAX); + + err = emc_set_min_rate(emc, rate, EMC_RATE_ICC); + if (err) + return err; + return 0; } @@ -334,6 +460,8 @@ static int tegra186_emc_probe(struct platform_device *pdev) platform_set_drvdata(pdev, emc); emc->dev = &pdev->dev; + tegra_emc_rate_requests_init(emc); + if (tegra_bpmp_mrq_is_supported(emc->bpmp, MRQ_EMC_DVFS_LATENCY)) { err = tegra186_emc_get_emc_dvfs_latency(emc); if (err)