mmc: sdhci-esdhc-imx: reset tuning circuit when power on mmc card

USDHC tuning circuit should be reset before every time card enumeration
or re-enumeration.

SD3.0 card need tuning. For SDR104 card, when system suspend in standby
mode, and then resume back, the IO timing is still SDR104(tuned) which
may result in card re-enumeration fail in low card speed(400khz) for some
cards. And we did meet the issue that in certain probability, SDR104
card meet mmc command CRC/Timeout error when send CMD2 during mmc bus
resume.

This patch reset the tuning circuit when the ios timing is
MMC_TIMING_LEGACY/MMC_TIMING_MMC_HS/MMC_TIMING_SD_HS, which means both
mmc_power_up() and mmc_power_off() will reset the tuning circuit.

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
Acked-by: Dong Aisheng <aisheng.dong@nxp.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Author: Haibo Chen

drivers/mmc/host/sdhci-esdhc-imx.c

@@ -889,6 +889,28 @@ static void esdhc_set_strobe_dll(struct sdhci_host *host)
 	}
 }
 
+static void esdhc_reset_tuning(struct sdhci_host *host)
+{
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct pltfm_imx_data *imx_data = sdhci_pltfm_priv(pltfm_host);
+	u32 ctrl;
+
+	/* Rest the tuning circurt */
+	if (esdhc_is_usdhc(imx_data)) {
+		if (imx_data->socdata->flags & ESDHC_FLAG_MAN_TUNING) {
+			ctrl = readl(host->ioaddr + ESDHC_MIX_CTRL);
+			ctrl &= ~ESDHC_MIX_CTRL_SMPCLK_SEL;
+			ctrl &= ~ESDHC_MIX_CTRL_FBCLK_SEL;
+			writel(ctrl, host->ioaddr + ESDHC_MIX_CTRL);
+			writel(0, host->ioaddr + ESDHC_TUNE_CTRL_STATUS);
+		} else if (imx_data->socdata->flags & ESDHC_FLAG_STD_TUNING) {
+			ctrl = readl(host->ioaddr + SDHCI_ACMD12_ERR);
+			ctrl &= ~ESDHC_MIX_CTRL_SMPCLK_SEL;
+			writel(ctrl, host->ioaddr + SDHCI_ACMD12_ERR);
+		}
+	}
+}
+
 static void esdhc_set_uhs_signaling(struct sdhci_host *host, unsigned timing)
 {
 	u32 m;
@@ -932,6 +954,10 @@ static void esdhc_set_uhs_signaling(struct sdhci_host *host, unsigned timing)
 		host->ops->set_clock(host, host->clock);
 		esdhc_set_strobe_dll(host);
 		break;
+	case MMC_TIMING_LEGACY:
+	default:
+		esdhc_reset_tuning(host);
+		break;
 	}
 
 	esdhc_change_pinstate(host, timing);