mmc: tegra: Implement periodic pad calibration

Rerun the pad calibration procedure before sdhci_request() if
the 100 ms recalibration interval has been exceeded.
Signed-off-by: Aapo Vienamo <avienamo@nvidia.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-tegra.c

@@ -30,6 +30,7 @@
 #include <linux/mmc/mmc.h>
 #include <linux/mmc/slot-gpio.h>
 #include <linux/gpio/consumer.h>
+#include <linux/ktime.h>
 
 #include "sdhci-pltfm.h"
 
@@ -122,6 +123,7 @@ struct sdhci_tegra {
 	struct pinctrl_state *pinctrl_state_1v8;
 
 	struct sdhci_tegra_autocal_offsets autocal_offsets;
+	ktime_t last_calib;
 
 	u32 default_tap;
 	u32 default_trim;
@@ -555,6 +557,22 @@ static void tegra_sdhci_parse_pad_autocal_dt(struct sdhci_host *host)
 		autocal->pull_down_hs400 = autocal->pull_down_1v8;
 }
 
+static void tegra_sdhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
+{
+	struct sdhci_host *host = mmc_priv(mmc);
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
+	ktime_t since_calib = ktime_sub(ktime_get(), tegra_host->last_calib);
+
+	/* 100 ms calibration interval is specified in the TRM */
+	if (ktime_to_ms(since_calib) > 100) {
+		tegra_sdhci_pad_autocalib(host);
+		tegra_host->last_calib = ktime_get();
+	}
+
+	sdhci_request(mmc, mrq);
+}
+
 static void tegra_sdhci_parse_tap_and_trim(struct sdhci_host *host)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
@@ -1045,6 +1063,10 @@ static int sdhci_tegra_probe(struct platform_device *pdev)
 				sdhci_tegra_start_signal_voltage_switch;
 	}
 
+	/* Hook to periodically rerun pad calibration */
+	if (soc_data->nvquirks & NVQUIRK_HAS_PADCALIB)
+		host->mmc_host_ops.request = tegra_sdhci_request;
+
 	host->mmc_host_ops.hs400_enhanced_strobe =
 			tegra_sdhci_hs400_enhanced_strobe;