[U-Boot] [PATCH 16/33] rockchip: clk: rk3288: add support for the clock phase

[Ziyuan Xu]

This patch adds phase adjustment for mmc clock(ciu_sample), which is
used to select the optimal sampling point of a data input.

The phase shift is achieved through 255 delay elements(40-80
picoseconds),  and calculate the number of delay element via clock
frequency.

Signed-off-by: Ziyuan Xu <xzy.xu at rock-chips.com>
---

 drivers/clk/rockchip/clk_rk3288.c | 124 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)

diff --git a/drivers/clk/rockchip/clk_rk3288.c b/drivers/clk/rockchip/clk_rk3288.c
index b924a3b..3279e01 100644
--- a/drivers/clk/rockchip/clk_rk3288.c
+++ b/drivers/clk/rockchip/clk_rk3288.c
@@ -514,6 +514,7 @@ static ulong rockchip_mmc_get_clk(struct rk3288_cru *cru, uint gclk_rate,
 	switch (periph) {
 	case HCLK_EMMC:
 	case SCLK_EMMC:
+	case SCLK_EMMC_SAMPLE:
 		con = readl(&cru->cru_clksel_con[12]);
 		mux = (con >> EMMC_PLL_SHIFT) & EMMC_PLL_MASK;
 		div = (con >> EMMC_DIV_SHIFT) & EMMC_DIV_MASK;
@@ -669,7 +670,9 @@ static ulong rk3288_clk_get_rate(struct clk *clk)
 	case HCLK_SDMMC:
 	case HCLK_SDIO0:
 	case SCLK_EMMC:
+	case SCLK_EMMC_SAMPLE:
 	case SCLK_SDMMC:
+	case SCLK_SDMMC_SAMPLE:
 	case SCLK_SDIO0:
 		new_rate = rockchip_mmc_get_clk(priv->cru, gclk_rate, clk->id);
 		break;
@@ -784,9 +787,130 @@ static ulong rk3288_clk_set_rate(struct clk *clk, ulong rate)
 	return new_rate;
 }
 
+#define ROCKCHIP_MMC_DELAY_SEL		BIT(10)
+#define ROCKCHIP_MMC_DEGREE_MASK	0x3
+#define ROCKCHIP_MMC_DELAYNUM_OFFSET	2
+#define ROCKCHIP_MMC_DELAYNUM_MASK	(0xff << ROCKCHIP_MMC_DELAYNUM_OFFSET)
+
+#define PSECS_PER_SEC 1000000000000LL
+/*
+ * Each fine delay is between 44ps-77ps. Assume each fine delay is 60ps to
+ * simplify calculations. So 45degs could be anywhere between 33deg and 57.8deg.
+ */
+#define ROCKCHIP_MMC_DELAY_ELEMENT_PSEC 60
+
+int rockchip_mmc_get_phase(struct clk *clk)
+{
+	struct rk3288_clk_priv *priv = dev_get_priv(clk->dev);
+	struct rk3288_cru *cru = priv->cru;
+	u32 raw_value, delay_num;
+	u16 degrees = 0;
+	ulong rate;
+
+	rate = rk3288_clk_get_rate(clk);
+
+	if (rate < 0)
+		return rate;
+
+	if (clk->id == SCLK_EMMC_SAMPLE)
+		raw_value = readl(&cru->cru_emmc_con[1]);
+	else
+		raw_value = readl(&cru->cru_sdmmc_con[1]);
+
+	degrees = (raw_value & ROCKCHIP_MMC_DEGREE_MASK) * 90;
+
+	if (raw_value & ROCKCHIP_MMC_DELAY_SEL) {
+		/* degrees/delaynum * 10000 */
+		unsigned long factor = (ROCKCHIP_MMC_DELAY_ELEMENT_PSEC / 10) *
+					36 * (rate / 1000000);
+
+		delay_num = (raw_value & ROCKCHIP_MMC_DELAYNUM_MASK);
+		delay_num >>= ROCKCHIP_MMC_DELAYNUM_OFFSET;
+		degrees += DIV_ROUND_CLOSEST(delay_num * factor, 10000);
+	}
+
+	return degrees % 360;
+}
+
+int rockchip_mmc_set_phase(struct clk *clk, u32 degrees)
+{
+	struct rk3288_clk_priv *priv = dev_get_priv(clk->dev);
+	struct rk3288_cru *cru = priv->cru;
+	u8 nineties, remainder, delay_num;
+	u32 raw_value, delay;
+	ulong rate;
+
+	rate = rk3288_clk_get_rate(clk);
+
+	if (rate < 0)
+		return rate;
+
+	nineties = degrees / 90;
+	remainder = (degrees % 90);
+
+	/*
+	 * Convert to delay; do a little extra work to make sure we
+	 * don't overflow 32-bit / 64-bit numbers.
+	 */
+	delay = 10000000; /* PSECS_PER_SEC / 10000 / 10 */
+	delay *= remainder;
+	delay = DIV_ROUND_CLOSEST(delay, (rate / 1000) * 36 *
+				(ROCKCHIP_MMC_DELAY_ELEMENT_PSEC / 10));
+
+	delay_num = (u8)min_t(u32, delay, 255);
+
+	raw_value = delay_num ? ROCKCHIP_MMC_DELAY_SEL : 0;
+	raw_value |= delay_num << ROCKCHIP_MMC_DELAYNUM_OFFSET;
+	raw_value |= nineties;
+
+	if (clk->id == SCLK_EMMC_SAMPLE)
+		writel(raw_value | 0xffff0000, &cru->cru_emmc_con[1]);
+	else
+		writel(raw_value | 0xffff0000, &cru->cru_sdmmc_con[1]);
+
+	debug("mmc set_phase(%d) delay_nums=%u reg=%#x actual_degrees=%d\n",
+	      degrees, delay_num, raw_value, rockchip_mmc_get_phase(clk));
+
+	return 0;
+}
+
+static int rk3288_clk_get_phase(struct clk *clk)
+{
+	int ret;
+
+	switch (clk->id) {
+	case SCLK_EMMC_SAMPLE:
+	case SCLK_SDMMC_SAMPLE:
+		ret = rockchip_mmc_get_phase(clk);
+		break;
+	default:
+		return -ENOENT;
+	}
+
+	return ret;
+}
+
+static int rk3288_clk_set_phase(struct clk *clk, int degrees)
+{
+	int ret;
+
+	switch (clk->id) {
+	case SCLK_EMMC_SAMPLE:
+	case SCLK_SDMMC_SAMPLE:
+		ret = rockchip_mmc_set_phase(clk, degrees);
+		break;
+	default:
+		return -ENOENT;
+	}
+
+	return ret;
+}
+
 static struct clk_ops rk3288_clk_ops = {
 	.get_rate	= rk3288_clk_get_rate,
 	.set_rate	= rk3288_clk_set_rate,
+	.get_phase	= rk3288_clk_get_phase,
+	.set_phase	= rk3288_clk_set_phase,
 };
 
 static int rk3288_clk_ofdata_to_platdata(struct udevice *dev)
-- 
2.7.4