[PATCH v6 5/8] mmc: sdhci-of-arasan: Add support to set clock phase delays for SD

[Manish Narani]

Add support to read Clock Phase Delays from the DT and set it via
clk_set_phase() API from clock framework. Some of the controllers might
have their own handling of setting clock delays, for this keep the
set_clk_delays as function pointer which can be assigned controller
specific handling of the same.

Signed-off-by: Manish Narani <manish.narani@xxxxxxxxxx>
---
 drivers/mmc/host/sdhci-of-arasan.c | 92 ++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)

diff --git a/drivers/mmc/host/sdhci-of-arasan.c b/drivers/mmc/host/sdhci-of-arasan.c
index b75ba780f902..9452ae01f6fa 100644
--- a/drivers/mmc/host/sdhci-of-arasan.c
+++ b/drivers/mmc/host/sdhci-of-arasan.c
@@ -77,12 +77,18 @@ struct sdhci_arasan_soc_ctl_map {
  * @sdcardclk:		Pointer to normal 'struct clock' for sdcardclk_hw.
  * @sampleclk_hw:	Struct for the clock we might provide to a PHY.
  * @sampleclk:		Pointer to normal 'struct clock' for sampleclk_hw.
+ * @clk_phase_in:	Array of Input Clock Phase Delays for all speed modes
+ * @clk_phase_out:	Array of Output Clock Phase Delays for all speed modes
+ * @set_clk_delays:	Function pointer for setting Clock Delays
  */
 struct sdhci_arasan_clk_data {
 	struct clk_hw	sdcardclk_hw;
 	struct clk      *sdcardclk;
 	struct clk_hw	sampleclk_hw;
 	struct clk      *sampleclk;
+	int		clk_phase_in[MMC_TIMING_MMC_HS400 + 1];
+	int		clk_phase_out[MMC_TIMING_MMC_HS400 + 1];
+	void		(*set_clk_delays)(struct sdhci_host *host);
 };
 
 /**
@@ -186,6 +192,7 @@ static void sdhci_arasan_set_clock(struct sdhci_host *host, unsigned int clock)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host);
+	struct sdhci_arasan_clk_data *clk_data = &sdhci_arasan->clk_data;
 	bool ctrl_phy = false;
 
 	if (!IS_ERR(sdhci_arasan->phy)) {
@@ -227,6 +234,10 @@ static void sdhci_arasan_set_clock(struct sdhci_host *host, unsigned int clock)
 		sdhci_arasan->is_phy_on = false;
 	}
 
+	/* Set the Input and Output Clock Phase Delays */
+	if (clk_data->set_clk_delays)
+		clk_data->set_clk_delays(host);
+
 	sdhci_set_clock(host, clock);
 
 	if (sdhci_arasan->quirks & SDHCI_ARASAN_QUIRK_CLOCK_UNSTABLE)
@@ -650,6 +661,85 @@ static void sdhci_arasan_update_baseclkfreq(struct sdhci_host *host)
 	sdhci_arasan_syscon_write(host, &soc_ctl_map->baseclkfreq, mhz);
 }
 
+static void sdhci_arasan_set_clk_delays(struct sdhci_host *host)
+{
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host);
+	struct sdhci_arasan_clk_data *clk_data = &sdhci_arasan->clk_data;
+
+	clk_set_phase(clk_data->sampleclk,
+		      clk_data->clk_phase_in[host->timing]);
+	clk_set_phase(clk_data->sdcardclk,
+		      clk_data->clk_phase_out[host->timing]);
+}
+
+static void arasan_dt_read_clk_phase(struct device *dev,
+				     struct sdhci_arasan_clk_data *clk_data,
+				     unsigned int timing, const char *prop)
+{
+	struct device_node *np = dev->of_node;
+
+	int clk_phase[2] = {0};
+
+	/*
+	 * Read Tap Delay values from DT, if the DT does not contain the
+	 * Tap Values then use the pre-defined values.
+	 */
+	if (of_property_read_variable_u32_array(np, prop, &clk_phase[0],
+						2, 0)) {
+		dev_dbg(dev, "Using predefined clock phase for %s = %d %d\n",
+			prop, clk_data->clk_phase_in[timing],
+			clk_data->clk_phase_out[timing]);
+		return;
+	}
+
+	/* The values read are Input and Output Clock Delays in order */
+	clk_data->clk_phase_in[timing] = clk_phase[0];
+	clk_data->clk_phase_out[timing] = clk_phase[1];
+}
+
+/**
+ * arasan_dt_parse_clk_phases - Read Clock Delay values from DT
+ *
+ * Called at initialization to parse the values of Clock Delays.
+ *
+ * @dev:		Pointer to our struct device.
+ * @clk_data:		Pointer to the Clock Data structure
+ */
+static void arasan_dt_parse_clk_phases(struct device *dev,
+				       struct sdhci_arasan_clk_data *clk_data)
+{
+	/*
+	 * This has been kept as a pointer and is assigned a function here.
+	 * So that different controller variants can assign their own handling
+	 * function.
+	 */
+	clk_data->set_clk_delays = sdhci_arasan_set_clk_delays;
+
+	arasan_dt_read_clk_phase(dev, clk_data, MMC_TIMING_LEGACY,
+				 "clk-phase-legacy");
+	arasan_dt_read_clk_phase(dev, clk_data, MMC_TIMING_MMC_HS,
+				 "clk-phase-mmc-hs");
+	arasan_dt_read_clk_phase(dev, clk_data, MMC_TIMING_SD_HS,
+				 "clk-phase-sd-hs");
+	arasan_dt_read_clk_phase(dev, clk_data, MMC_TIMING_UHS_SDR12,
+				 "clk-phase-uhs-sdr12");
+	arasan_dt_read_clk_phase(dev, clk_data, MMC_TIMING_UHS_SDR25,
+				 "clk-phase-uhs-sdr25");
+	arasan_dt_read_clk_phase(dev, clk_data, MMC_TIMING_UHS_SDR50,
+				 "clk-phase-uhs-sdr50");
+	arasan_dt_read_clk_phase(dev, clk_data, MMC_TIMING_UHS_SDR104,
+				 "clk-phase-uhs-sdr104");
+	arasan_dt_read_clk_phase(dev, clk_data, MMC_TIMING_UHS_DDR50,
+				 "clk-phase-uhs-ddr50");
+	arasan_dt_read_clk_phase(dev, clk_data, MMC_TIMING_MMC_DDR52,
+				 "clk-phase-mmc-ddr52");
+	arasan_dt_read_clk_phase(dev, clk_data, MMC_TIMING_MMC_HS200,
+				 "clk-phase-mmc-hs200");
+	arasan_dt_read_clk_phase(dev, clk_data, MMC_TIMING_MMC_HS400,
+				 "clk-phase-mmc-hs400");
+}
+
 /**
  * sdhci_arasan_register_sdcardclk - Register the sdcardclk for a PHY to use
  *
@@ -942,6 +1032,8 @@ static int sdhci_arasan_probe(struct platform_device *pdev)
 	if (ret)
 		goto clk_disable_all;
 
+	arasan_dt_parse_clk_phases(&pdev->dev, &sdhci_arasan->clk_data);
+
 	ret = mmc_of_parse(host->mmc);
 	if (ret) {
 		if (ret != -EPROBE_DEFER)
-- 
2.17.1