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Message-Id: <20241014060130.1162629-4-haibo.chen@nxp.com>
Date: Mon, 14 Oct 2024 14:01:29 +0800
From: haibo.chen@....com
To: adrian.hunter@...el.com,
	ulf.hansson@...aro.org,
	linux-mmc@...r.kernel.org
Cc: imx@...ts.linux.dev,
	haibo.chen@....com,
	shawnguo@...nel.org,
	s.hauer@...gutronix.de,
	kernel@...gutronix.de,
	festevam@...il.com,
	s32@....com,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 3/4] mmc: host: sdhci-esdhc-imx: save tuning value for the SDIO card as wakeup source

From: Haibo Chen <haibo.chen@....com>

For some SoCs like imx6ul(l/z)/imx7d/imx93, during system PM, usdhc will
totally power off, so the internal tuning status will lost. Here add
save/restore the tuning value for any command after system resume back
when re-tuning hold.

The tipical case is for the SDIO which contain flag MMC_PM_KEEP_POWER,
and contain pm_flags MMC_PM_WAKE_SDIO_IRQ. in mmc_sdio_suspend(), SDIO
will switch to 1 bit mode, and switch back to 4 bit mode when resume back.
According to spec, tuning command do not support in 1 bit mode. So when
send cmd52 to switch back to 4 bit mode, need to hold re-tuning. But this
cmd52 still need a correct sample point, otherwise will meet command CRC
error, so need to keep the previous tuning value.

Signed-off-by: Haibo Chen <haibo.chen@....com>
---
 drivers/mmc/host/sdhci-esdhc-imx.c | 94 +++++++++++++++++++++++++++++-
 1 file changed, 91 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
index 18febfeb60cf..4173967022d0 100644
--- a/drivers/mmc/host/sdhci-esdhc-imx.c
+++ b/drivers/mmc/host/sdhci-esdhc-imx.c
@@ -80,6 +80,9 @@
 #define  ESDHC_TUNE_CTRL_STEP		1
 #define  ESDHC_TUNE_CTRL_MIN		0
 #define  ESDHC_TUNE_CTRL_MAX		((1 << 7) - 1)
+#define ESDHC_TUNE_CTRL_STATUS_TAP_SEL_PRE_MASK		0x7f000000
+#define ESDHC_TUNE_CTRL_STATUS_TAP_SEL_PRE_SHIFT	24
+#define ESDHC_TUNE_CTRL_STATUS_DLY_CELL_SET_PRE_SHIFT	8
 
 /* strobe dll register */
 #define ESDHC_STROBE_DLL_CTRL		0x70
@@ -234,6 +237,7 @@ struct esdhc_platform_data {
 	unsigned int tuning_step;       /* The delay cell steps in tuning procedure */
 	unsigned int tuning_start_tap;	/* The start delay cell point in tuning procedure */
 	unsigned int strobe_dll_delay_target;	/* The delay cell for strobe pad (read clock) */
+	unsigned int saved_tuning_delay_cell;	/* save the value of tuning delay cell */
 };
 
 struct esdhc_soc_data {
@@ -1055,7 +1059,7 @@ 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;
+	u32 ctrl, tuning_ctrl;
 	int ret;
 
 	/* Reset the tuning circuit */
@@ -1069,6 +1073,17 @@ static void esdhc_reset_tuning(struct sdhci_host *host)
 			writel(0, host->ioaddr + ESDHC_TUNE_CTRL_STATUS);
 		} else if (imx_data->socdata->flags & ESDHC_FLAG_STD_TUNING) {
 			writel(ctrl, host->ioaddr + ESDHC_MIX_CTRL);
+
+			/*
+			 * enable the std tuning just in case it cleared in
+			 * sdhc_esdhc_tuning_restore.
+			 */
+			tuning_ctrl = readl(host->ioaddr + ESDHC_TUNING_CTRL);
+			if (!(tuning_ctrl & ESDHC_STD_TUNING_EN)) {
+				tuning_ctrl |= ESDHC_STD_TUNING_EN;
+				writel(tuning_ctrl, host->ioaddr + ESDHC_TUNING_CTRL);
+			}
+
 			ctrl = readl(host->ioaddr + SDHCI_AUTO_CMD_STATUS);
 			ctrl &= ~ESDHC_MIX_CTRL_SMPCLK_SEL;
 			ctrl &= ~ESDHC_MIX_CTRL_EXE_TUNE;
@@ -1147,7 +1162,8 @@ static void esdhc_prepare_tuning(struct sdhci_host *host, u32 val)
 	reg |= ESDHC_MIX_CTRL_EXE_TUNE | ESDHC_MIX_CTRL_SMPCLK_SEL |
 			ESDHC_MIX_CTRL_FBCLK_SEL;
 	writel(reg, host->ioaddr + ESDHC_MIX_CTRL);
-	writel(val << 8, host->ioaddr + ESDHC_TUNE_CTRL_STATUS);
+	writel(val << ESDHC_TUNE_CTRL_STATUS_DLY_CELL_SET_PRE_SHIFT,
+				host->ioaddr + ESDHC_TUNE_CTRL_STATUS);
 	dev_dbg(mmc_dev(host->mmc),
 		"tuning with delay 0x%x ESDHC_TUNE_CTRL_STATUS 0x%x\n",
 			val, readl(host->ioaddr + ESDHC_TUNE_CTRL_STATUS));
@@ -1555,6 +1571,58 @@ static void sdhci_esdhc_imx_hwinit(struct sdhci_host *host)
 	}
 }
 
+static void sdhc_esdhc_tuning_save(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 reg;
+
+	/*
+	 * SD/eMMC do not need this tuning save because it will re-init
+	 * after system resume back.
+	 * Here save the tuning delay value for SDIO device since it may
+	 * keep power during system PM. And for usdhc, only SDR50 and
+	 * SDR104 mode for SDIO devide need to do tuning, and need to
+	 * save/restore.
+	 */
+	if ((host->timing == MMC_TIMING_UHS_SDR50) |
+			(host->timing == MMC_TIMING_UHS_SDR104)) {
+		reg = readl(host->ioaddr + ESDHC_TUNE_CTRL_STATUS);
+		reg = (reg & ESDHC_TUNE_CTRL_STATUS_TAP_SEL_PRE_MASK) >>
+				ESDHC_TUNE_CTRL_STATUS_TAP_SEL_PRE_SHIFT;
+		imx_data->boarddata.saved_tuning_delay_cell = reg;
+	}
+}
+
+static void sdhc_esdhc_tuning_restore(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 reg;
+
+	if ((host->timing == MMC_TIMING_UHS_SDR50) |
+			(host->timing == MMC_TIMING_UHS_SDR104)) {
+		/*
+		 * restore the tuning delay value actually is a
+		 * manual tuning method, so clear the standard
+		 * tuning enable bit here. Will set back this
+		 * ESDHC_STD_TUNING_EN in esdhc_reset_tuning()
+		 * when trigger re-tuning.
+		 */
+		reg = readl(host->ioaddr + ESDHC_TUNING_CTRL);
+		reg &= ~ESDHC_STD_TUNING_EN;
+		writel(reg, host->ioaddr + ESDHC_TUNING_CTRL);
+
+		reg = readl(host->ioaddr + ESDHC_MIX_CTRL);
+		reg |= ESDHC_MIX_CTRL_SMPCLK_SEL | ESDHC_MIX_CTRL_FBCLK_SEL;
+		writel(reg, host->ioaddr + ESDHC_MIX_CTRL);
+
+		writel(imx_data->boarddata.saved_tuning_delay_cell <<
+				ESDHC_TUNE_CTRL_STATUS_DLY_CELL_SET_PRE_SHIFT,
+				host->ioaddr + ESDHC_TUNE_CTRL_STATUS);
+	}
+}
+
 static void esdhc_cqe_enable(struct mmc_host *mmc)
 {
 	struct sdhci_host *host = mmc_priv(mmc);
@@ -1883,7 +1951,17 @@ static int sdhci_esdhc_suspend(struct device *dev)
 		(host->tuning_mode != SDHCI_TUNING_MODE_1)) {
 		mmc_retune_timer_stop(host->mmc);
 		mmc_retune_needed(host->mmc);
-	}
+
+		/*
+		 * For the SDIO device need to keep power during system PM, and enable
+		 * wakeup, need to save the tuning delay value just in case the retuning
+		 * is hold when SDIO resume, but still need to switch to 4 bit bus width.
+		 */
+		if (host->mmc->sdio_irqs && mmc_card_keep_power(host->mmc) &&
+				(esdhc_is_usdhc(imx_data)))
+			sdhc_esdhc_tuning_save(host);
+
+		}
 
 	if (device_may_wakeup(dev)) {
 		ret = sdhci_enable_irq_wakeups(host);
@@ -1903,6 +1981,8 @@ static int sdhci_esdhc_suspend(struct device *dev)
 static int sdhci_esdhc_resume(struct device *dev)
 {
 	struct sdhci_host *host = dev_get_drvdata(dev);
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct pltfm_imx_data *imx_data = sdhci_pltfm_priv(pltfm_host);
 	int ret;
 
 	ret = mmc_gpio_set_cd_wake(host->mmc, false);
@@ -1915,6 +1995,14 @@ static int sdhci_esdhc_resume(struct device *dev)
 	if (host->irq_wake_enabled)
 		sdhci_disable_irq_wakeups(host);
 
+	/*
+	 * Restore the saved tuning delay value for the SDIO device
+	 * which enabled wakeup and keep power during system PM.
+	 */
+	if ((imx_data->socdata->flags & ESDHC_FLAG_STATE_LOST_IN_LPMODE) &&
+	    mmc_card_keep_power(host->mmc) && mmc_card_wake_sdio_irq(host->mmc))
+		sdhc_esdhc_tuning_restore(host);
+
 	pm_runtime_mark_last_busy(dev);
 	pm_runtime_put_autosuspend(dev);
 
-- 
2.34.1


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