Re: [PATCH 2/2] mmc: host: sunxi: add support for A64 mmc controller

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Hi,

On 30-07-16 11:36, Icenowy Zheng wrote:
A64 SoC features a MMC controller which need only the mod clock, and can
calibrate delay by itself. This patch adds support for the new MMC
controller IP core.

Signed-off-by: Icenowy Zheng <icenowy@xxxxxxxx>

Cool stuff, thanks for your work on this!

---
 drivers/mmc/host/sunxi-mmc.c | 166 +++++++++++++++++++++++++++++++------------
 1 file changed, 122 insertions(+), 44 deletions(-)

diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c
index 2ee4c21..ac56bcf 100644
--- a/drivers/mmc/host/sunxi-mmc.c
+++ b/drivers/mmc/host/sunxi-mmc.c
@@ -72,6 +72,14 @@
 #define SDXC_REG_CHDA	(0x90)
 #define SDXC_REG_CBDA	(0x94)

+/* New registers introduced in A64 */
+#define SDXC_REG_A12A		0x058 /* SMC Auto Command 12 Register */
+#define SDXC_REG_SD_NTSR	0x05C /* SMC New Timing Set Register */
+#define SDXC_REG_DRV_DL		0x140 /* Drive Delay Control Register */
+#define SDXC_REG_SAMP_DL_REG	0x144 /* SMC sample delay control */
+#define SDXC_REG_DS_DL_REG	0x148 /* SMC data strobe delay control */
+
+
 #define mmc_readl(host, reg) \
 	readl((host)->reg_base + SDXC_##reg)
 #define mmc_writel(host, reg, value) \
@@ -217,6 +225,15 @@
 #define SDXC_CLK_50M_DDR	3
 #define SDXC_CLK_50M_DDR_8BIT	4

+#define SDXC_2X_TIMING_MODE	BIT(31)
+
+#define SDXC_CAL_START		BIT(15)
+#define SDXC_CAL_DONE		BIT(14)
+#define SDXC_CAL_DL_SHIFT	8
+#define SDXC_CAL_DL_SW_EN	BIT(7)
+#define SDXC_CAL_DL_SW_SHIFT	0
+#define SDXC_CAL_DL_MASK	0x3f
+
 struct sunxi_mmc_clk_delay {
 	u32 output;
 	u32 sample;
@@ -261,6 +278,9 @@ struct sunxi_mmc_host {

 	/* vqmmc */
 	bool		vqmmc_enabled;
+
+	/* does the IP block support autocalibration? */
+	bool		can_calibrate;
 };

 static int sunxi_mmc_reset_host(struct sunxi_mmc_host *host)
@@ -653,10 +673,66 @@ static int sunxi_mmc_oclk_onoff(struct sunxi_mmc_host *host, u32 oclk_en)
 	return 0;
 }

+static int sunxi_mmc_calibrate(struct sunxi_mmc_host *host,
+			       struct mmc_ios *ios, int reg_off)
+{
+	u32 reg = readl(host->reg_base + reg_off);
+	u32 delay;
+
+	reg &= ~(SDXC_CAL_DL_MASK << SDXC_CAL_DL_SW_SHIFT);
+	reg &= ~SDXC_CAL_DL_SW_EN;
+
+	writel(reg | SDXC_CAL_START, host->reg_base + reg_off);
+
+	dev_dbg(mmc_dev(host->mmc), "calibration started\n");
+
+	while (!((reg = readl(host->reg_base + reg_off)) & SDXC_CAL_DONE))
+		cpu_relax();
+
+	delay = (reg >> SDXC_CAL_DL_SHIFT) & SDXC_CAL_DL_MASK;
+
+	reg &= ~SDXC_CAL_START;
+	reg |= (delay << SDXC_CAL_DL_SW_SHIFT) | SDXC_CAL_DL_SW_EN;
+
+	writel(reg, host->reg_base + reg_off);
+
+	dev_dbg(mmc_dev(host->mmc), "calibration ended, res is 0x%x\n", reg);
+
+	return 0;
+}
+
+static int sunxi_mmc_determine_delays(struct sunxi_mmc_host *host,
+				      struct mmc_ios *ios, int rate)
+{
+	int index;
+
+	if (rate <= 400000) {
+		index = SDXC_CLK_400K;
+	} else if (rate <= 25000000) {
+		index = SDXC_CLK_25M;
+	} else if (rate <= 52000000) {
+		if (ios->timing != MMC_TIMING_UHS_DDR50 &&
+		    ios->timing != MMC_TIMING_MMC_DDR52) {
+			index = SDXC_CLK_50M;
+		} else if (ios->bus_width == MMC_BUS_WIDTH_8) {
+			index = SDXC_CLK_50M_DDR_8BIT;
+		} else {
+			index = SDXC_CLK_50M_DDR;
+		}
+	} else {
+		return -EINVAL;
+	}
+
+	clk_set_phase(host->clk_sample, host->clk_delays[index].sample);
+	clk_set_phase(host->clk_output, host->clk_delays[index].output);
+
+	return 0;
+}
+

The factoring out of this into a function really should be done in
a separate preparation patch, that will also make the patch making
the actual functional changes much easier to read.

Regards,

Hans



 static int sunxi_mmc_clk_set_rate(struct sunxi_mmc_host *host,
 				  struct mmc_ios *ios)
 {
-	u32 rate, oclk_dly, rval, sclk_dly;
+	u32 rate, rval;
 	u32 clock = ios->clock;
 	int ret;

@@ -692,32 +768,18 @@ static int sunxi_mmc_clk_set_rate(struct sunxi_mmc_host *host,
 	}
 	mmc_writel(host, REG_CLKCR, rval);

-	/* determine delays */
-	if (rate <= 400000) {
-		oclk_dly = host->clk_delays[SDXC_CLK_400K].output;
-		sclk_dly = host->clk_delays[SDXC_CLK_400K].sample;
-	} else if (rate <= 25000000) {
-		oclk_dly = host->clk_delays[SDXC_CLK_25M].output;
-		sclk_dly = host->clk_delays[SDXC_CLK_25M].sample;
-	} else if (rate <= 52000000) {
-		if (ios->timing != MMC_TIMING_UHS_DDR50 &&
-		    ios->timing != MMC_TIMING_MMC_DDR52) {
-			oclk_dly = host->clk_delays[SDXC_CLK_50M].output;
-			sclk_dly = host->clk_delays[SDXC_CLK_50M].sample;
-		} else if (ios->bus_width == MMC_BUS_WIDTH_8) {
-			oclk_dly = host->clk_delays[SDXC_CLK_50M_DDR_8BIT].output;
-			sclk_dly = host->clk_delays[SDXC_CLK_50M_DDR_8BIT].sample;
-		} else {
-			oclk_dly = host->clk_delays[SDXC_CLK_50M_DDR].output;
-			sclk_dly = host->clk_delays[SDXC_CLK_50M_DDR].sample;
-		}
+	if (host->can_calibrate) {
+		ret = sunxi_mmc_calibrate(host, ios, SDXC_REG_SAMP_DL_REG);
+		if (ret)
+			return ret;
+
+		/* TODO: enable calibrate on sdc2 SDXC_REG_DS_DL_REG of A64 */
 	} else {
-		return -EINVAL;
+		ret = sunxi_mmc_determine_delays(host, ios, rate);
+		if (ret)
+			return ret;
 	}

-	clk_set_phase(host->clk_sample, sclk_dly);
-	clk_set_phase(host->clk_output, oclk_dly);
-
 	return sunxi_mmc_oclk_onoff(host, 1);
 }

@@ -942,6 +1004,7 @@ static const struct of_device_id sunxi_mmc_of_match[] = {
 	{ .compatible = "allwinner,sun4i-a10-mmc", },
 	{ .compatible = "allwinner,sun5i-a13-mmc", },
 	{ .compatible = "allwinner,sun9i-a80-mmc", },
+	{ .compatible = "allwinner,sun50i-a64-mmc", },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, sunxi_mmc_of_match);
@@ -990,6 +1053,11 @@ static int sunxi_mmc_resource_request(struct sunxi_mmc_host *host,
 	else
 		host->clk_delays = sunxi_mmc_clk_delays;

+	if (of_device_is_compatible(np, "allwinner,sun50i-a64-mmc"))
+		host->can_calibrate = true;
+	else
+		host->can_calibrate = false;
+
 	ret = mmc_regulator_get_supply(host->mmc);
 	if (ret) {
 		if (ret != -EPROBE_DEFER)
@@ -1014,16 +1082,22 @@ static int sunxi_mmc_resource_request(struct sunxi_mmc_host *host,
 		return PTR_ERR(host->clk_mmc);
 	}

-	host->clk_output = devm_clk_get(&pdev->dev, "output");
-	if (IS_ERR(host->clk_output)) {
-		dev_err(&pdev->dev, "Could not get output clock\n");
-		return PTR_ERR(host->clk_output);
-	}
+	/* self-calibrate version of the IP block needs no output/sample */
+	if (!host->can_calibrate) {
+		host->clk_output = devm_clk_get(&pdev->dev, "output");
+		if (IS_ERR(host->clk_output)) {
+			dev_err(&pdev->dev, "Could not get output clock\n");
+			return PTR_ERR(host->clk_output);
+		}

-	host->clk_sample = devm_clk_get(&pdev->dev, "sample");
-	if (IS_ERR(host->clk_sample)) {
-		dev_err(&pdev->dev, "Could not get sample clock\n");
-		return PTR_ERR(host->clk_sample);
+		host->clk_sample = devm_clk_get(&pdev->dev, "sample");
+		if (IS_ERR(host->clk_sample)) {
+			dev_err(&pdev->dev, "Could not get sample clock\n");
+			return PTR_ERR(host->clk_sample);
+		}
+	} else {
+		host->clk_sample = NULL;
+		host->clk_output = NULL;
 	}

 	host->reset = devm_reset_control_get_optional(&pdev->dev, "ahb");
@@ -1042,16 +1116,18 @@ static int sunxi_mmc_resource_request(struct sunxi_mmc_host *host,
 		goto error_disable_clk_ahb;
 	}

-	ret = clk_prepare_enable(host->clk_output);
-	if (ret) {
-		dev_err(&pdev->dev, "Enable output clk err %d\n", ret);
-		goto error_disable_clk_mmc;
-	}
+	if (!host->can_calibrate) {
+		ret = clk_prepare_enable(host->clk_output);
+		if (ret) {
+			dev_err(&pdev->dev, "Enable output clk err %d\n", ret);
+			goto error_disable_clk_mmc;
+		}

-	ret = clk_prepare_enable(host->clk_sample);
-	if (ret) {
-		dev_err(&pdev->dev, "Enable sample clk err %d\n", ret);
-		goto error_disable_clk_output;
+		ret = clk_prepare_enable(host->clk_sample);
+		if (ret) {
+			dev_err(&pdev->dev, "Enable sample clk err %d\n", ret);
+			goto error_disable_clk_output;
+		}
 	}

 	if (!IS_ERR(host->reset)) {
@@ -1078,9 +1154,11 @@ error_assert_reset:
 	if (!IS_ERR(host->reset))
 		reset_control_assert(host->reset);
 error_disable_clk_sample:
-	clk_disable_unprepare(host->clk_sample);
+	if (!host->can_calibrate)
+		clk_disable_unprepare(host->clk_sample);
 error_disable_clk_output:
-	clk_disable_unprepare(host->clk_output);
+	if (!host->can_calibrate)
+		clk_disable_unprepare(host->clk_output);
 error_disable_clk_mmc:
 	clk_disable_unprepare(host->clk_mmc);
 error_disable_clk_ahb:

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