Re: [PATCH v5 10/12] mmc: sdhci-msm: Add HS400 platform support

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Hi Adrian,

Thanks for the complete review.


On 10/10/2016 5:38 PM, Adrian Hunter wrote:
On 05/10/16 17:40, Ritesh Harjani wrote:
From: Venkat Gopalakrishnan <venkatg@xxxxxxxxxxxxxx>

The following msm platform specific changes are added to support HS400.
- Allow tuning for HS400 mode.
- Configure HS400 timing mode using the VENDOR_SPECIFIC_FUNC register.

Signed-off-by: Venkat Gopalakrishnan <venkatg@xxxxxxxxxxxxxx>
Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxxx>
---
 drivers/mmc/host/sdhci-msm.c | 124 +++++++++++++++++++++++++++++++++++++++----
 1 file changed, 113 insertions(+), 11 deletions(-)

diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
index eb1a9e3..612fa82 100644
--- a/drivers/mmc/host/sdhci-msm.c
+++ b/drivers/mmc/host/sdhci-msm.c
@@ -31,6 +31,7 @@
 #define HC_MODE_EN		0x1
 #define CORE_POWER		0x0
 #define CORE_SW_RST		BIT(7)
+#define FF_CLK_SW_RST_DIS	BIT(13)

 #define CORE_PWRCTL_STATUS	0xdc
 #define CORE_PWRCTL_MASK	0xe0
@@ -64,11 +65,18 @@

 #define CORE_VENDOR_SPEC	0x10c
 #define CORE_CLK_PWRSAVE	BIT(1)
+#define CORE_HC_MCLK_SEL_DFLT	(2 << 8)
+#define CORE_HC_MCLK_SEL_HS400	(3 << 8)
+#define CORE_HC_MCLK_SEL_MASK	(3 << 8)
+#define CORE_HC_SELECT_IN_EN	(1 << 18)
+#define CORE_HC_SELECT_IN_HS400	(6 << 19)
+#define CORE_HC_SELECT_IN_MASK	(7 << 19)

 #define CORE_VENDOR_SPEC_CAPABILITIES0	0x11c

 #define TCXO_FREQ		19200000
 #define SDHCI_MSM_MIN_CLOCK	400000
+#define CORE_FREQ_100MHZ	(100 * 1000 * 1000)

 #define CDR_SELEXT_SHIFT	20
 #define CDR_SELEXT_MASK		(0xf << CDR_SELEXT_SHIFT)
@@ -87,6 +95,8 @@ struct sdhci_msm_host {
 	u32 clk_rate;
 	struct mmc_host *mmc;
 	bool use_14lpp_dll_reset;
+	bool tuning_done;
+	bool calibration_done;
 };

 /* Platform specific tuning */
@@ -175,8 +185,8 @@ out:
  * Find out the greatest range of consecuitive selected
  * DLL clock output phases that can be used as sampling
  * setting for SD3.0 UHS-I card read operation (in SDR104
- * timing mode) or for eMMC4.5 card read operation (in HS200
- * timing mode).
+ * timing mode) or for eMMC4.5 card read operation (in
+ * HS400/HS200 timing mode).
  * Select the 3/4 of the range and configure the DLL with the
  * selected DLL clock output phase.
  */
@@ -428,9 +438,10 @@ static int sdhci_msm_execute_tuning(struct sdhci_host *host, u32 opcode)
 	 * Tuning is required for SDR104, HS200 and HS400 cards and
 	 * if clock frequency is greater than 100MHz in these modes.
 	 */
-	if (host->clock <= 100 * 1000 * 1000 ||
-	    !((ios.timing == MMC_TIMING_MMC_HS200) ||
-	      (ios.timing == MMC_TIMING_UHS_SDR104)))
+	if (host->clock <= CORE_FREQ_100MHZ ||
+		!((ios.timing == MMC_TIMING_MMC_HS400) ||
+		(ios.timing == MMC_TIMING_MMC_HS200) ||
+		(ios.timing == MMC_TIMING_UHS_SDR104)))

Don't need () around ios.timing == MMC_TIMING_MMC_HS400 etc
Sure. Done.


 		return 0;

 retry:
@@ -488,7 +499,10 @@ static void sdhci_msm_set_uhs_signaling(struct sdhci_host *host,
 					unsigned int uhs)
 {
 	struct mmc_host *mmc = host->mmc;
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
 	u16 ctrl_2;
+	u32 config;

 	ctrl_2 = sdhci_readw(host, SDHCI_HOST_CONTROL2);
 	/* Select Bus Speed Mode for host */
@@ -503,6 +517,7 @@ static void sdhci_msm_set_uhs_signaling(struct sdhci_host *host,
 	case MMC_TIMING_UHS_SDR50:
 		ctrl_2 |= SDHCI_CTRL_UHS_SDR50;
 		break;
+	case MMC_TIMING_MMC_HS400:
 	case MMC_TIMING_MMC_HS200:
 	case MMC_TIMING_UHS_SDR104:
 		ctrl_2 |= SDHCI_CTRL_UHS_SDR104;
@@ -519,11 +534,33 @@ static void sdhci_msm_set_uhs_signaling(struct sdhci_host *host,
 	 * provide feedback clock, the mode selection can be any value less
 	 * than 3'b011 in bits [2:0] of HOST CONTROL2 register.
 	 */
-	if (host->clock <= 100000000 &&
-	    (uhs == MMC_TIMING_MMC_HS400 ||
-	     uhs == MMC_TIMING_MMC_HS200 ||
-	     uhs == MMC_TIMING_UHS_SDR104))
-		ctrl_2 &= ~SDHCI_CTRL_UHS_MASK;
+	if (host->clock <= CORE_FREQ_100MHZ) {
+		if ((uhs == MMC_TIMING_MMC_HS400) ||
+			(uhs == MMC_TIMING_MMC_HS200) ||
+			(uhs == MMC_TIMING_UHS_SDR104))
+			ctrl_2 &= ~SDHCI_CTRL_UHS_MASK;
+		/*
+		 * Make sure DLL is disabled when not required
+		 *
+		 * Write 1 to DLL_RST bit of DLL_CONFIG register
+		 */
+		config = readl_relaxed(host->ioaddr + CORE_DLL_CONFIG);
+		config |= CORE_DLL_RST;
+		writel_relaxed(config, host->ioaddr + CORE_DLL_CONFIG);
+
+		/* Write 1 to DLL_PDN bit of DLL_CONFIG register */
+		config = readl_relaxed(host->ioaddr + CORE_DLL_CONFIG);
+		config |= CORE_DLL_PDN;
+		writel_relaxed(config, host->ioaddr + CORE_DLL_CONFIG);
+
+		wmb(); /* drain writebuffer */

Memory barrier could use more explanation.
Ok.


+
+		/*
+		 * The DLL needs to be restored and CDCLP533 recalibrated
+		 * when the clock frequency is set back to 400MHz.
+		 */
+		msm_host->calibration_done = false;
+	}

 	dev_dbg(mmc_dev(mmc), "%s: clock=%u uhs=%u ctrl_2=0x%x\n",
 		mmc_hostname(host->mmc), host->clock, uhs, ctrl_2);
@@ -670,7 +707,7 @@ static void sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock)
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
 	struct mmc_ios curr_ios = host->mmc->ios;
-	u32 msm_clock;
+	u32 msm_clock, config;
 	int rc;

 	if (!clock)
@@ -691,6 +728,66 @@ static void sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock)
 	}
 	msm_clock = sdhci_msm_get_msm_clk_rate(host, clock);

+	/*
+	 * In general all timing modes are controlled via UHS mode select in
+	 * Host Control2 register. eMMC specific HS200/HS400 doesn't have
+	 * their respective modes defined here, hence we use these values.
+	 *
+	 * HS200 - SDR104 (Since they both are equivalent in functionality)
+	 * HS400 - This involves multiple configurations
+	 *		Initially SDR104 - when tuning is required as HS200
+	 *		Then when switching to DDR @ 400MHz (HS400) we use
+	 *		the vendor specific HC_SELECT_IN to control the mode.
+	 *
+	 * In addition to controlling the modes we also need to select the
+	 * correct input clock for DLL depending on the mode.
+	 *
+	 * HS400 - divided clock (free running MCLK/2)
+	 * All other modes - default (free running MCLK)
+	 */
+	if (curr_ios.timing == MMC_TIMING_MMC_HS400) {
+		/* Select the divided clock (free running MCLK/2) */
+		config = readl_relaxed(host->ioaddr + CORE_VENDOR_SPEC);
+		config &= ~CORE_HC_MCLK_SEL_MASK;
+		config |= CORE_HC_MCLK_SEL_HS400;
+
+		writel_relaxed(config, host->ioaddr + CORE_VENDOR_SPEC);
+		/*
+		 * Select HS400 mode using the HC_SELECT_IN from VENDOR SPEC
+		 * register
+		 */
+		if (msm_host->tuning_done && !msm_host->calibration_done) {


In this patch, tuning_done and calibration_done are never true.  Is that
intended?
Select HS400 which is done below should happen only after the tuning is performed. Hence the check of that variable above.
We set tuning_done = true in the next patch.

Please let me know if any concerns.

Similarly calibration_done is also getting set to true in the next patch.



+			/*
+			 * Write 0x6 to HC_SELECT_IN and 1 to HC_SELECT_IN_EN
+			 * field in VENDOR_SPEC_FUNC
+			 */
+			config = readl_relaxed(host->ioaddr + CORE_VENDOR_SPEC);
+			config |= CORE_HC_SELECT_IN_HS400;
+			config |= CORE_HC_SELECT_IN_EN;
+			writel_relaxed(config, host->ioaddr + CORE_VENDOR_SPEC);
+		}
+	} else {
+		/* Select the default clock (free running MCLK) */
+		config = readl_relaxed(host->ioaddr + CORE_VENDOR_SPEC);
+		config &= ~CORE_HC_MCLK_SEL_MASK;
+		config |= CORE_HC_MCLK_SEL_DFLT;
+		writel_relaxed(config, host->ioaddr + CORE_VENDOR_SPEC);
+
+		/*
+		 * Disable HC_SELECT_IN to be able to use the UHS mode select
+		 * configuration from Host Control2 register for all other
+		 * modes.
+		 *
+		 * Write 0 to HC_SELECT_IN and HC_SELECT_IN_EN field
+		 * in VENDOR_SPEC_FUNC
+		 */
+		config = readl_relaxed(host->ioaddr + CORE_VENDOR_SPEC);
+		config &= ~CORE_HC_SELECT_IN_EN;
+		config &= ~CORE_HC_SELECT_IN_MASK;
+		writel_relaxed(config, host->ioaddr + CORE_VENDOR_SPEC);
+	}
+	wmb(); /* drain writebuffer */

Memory barrier could use more explanation.
Ok. Sure.


+
 	if ((msm_clock != msm_host->clk_rate) && msm_host->clk_table) {
 		rc = clk_set_rate(msm_host->clk, msm_clock);
 		if (rc) {
@@ -876,6 +973,11 @@ static int sdhci_msm_probe(struct platform_device *pdev)
 	/* Set HC_MODE_EN bit in HC_MODE register */
 	writel_relaxed(HC_MODE_EN, (msm_host->core_mem + CORE_HC_MODE));

+	/* Set FF_CLK_SW_RST_DIS bit in HC_MODE register */
+	config = readl_relaxed(msm_host->core_mem + CORE_HC_MODE);
+	config |= FF_CLK_SW_RST_DIS;
+	writel_relaxed(config, msm_host->core_mem + CORE_HC_MODE);
+
 	host_version = readw_relaxed((host->ioaddr + SDHCI_HOST_VERSION));
 	dev_dbg(&pdev->dev, "Host Version: 0x%x Vendor Version 0x%x\n",
 		host_version, ((host_version & SDHCI_VENDOR_VER_MASK) >>



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