clk: X1000: Add support for calculat REFCLK of USB PHY.

Add functions for calculat the rate of REFCLK, which is needed by
USB PHY in Ingenic X1000 SoC.
Tested-by: 周正 (Zhou Zheng) <sernia.zhou@foxmail.com>
Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
Link: https://lore.kernel.org/r/20200630163852.47267-4-zhouyanjie@wanyeetech.comSigned-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/ingenic/x1000-cgu.c

@@ -48,8 +48,87 @@
 #define USBPCR_SIDDQ		BIT(21)
 #define USBPCR_OTG_DISABLE	BIT(20)
 
+/* bits within the USBPCR1 register */
+#define USBPCR1_REFCLKSEL_SHIFT	26
+#define USBPCR1_REFCLKSEL_MASK	(0x3 << USBPCR1_REFCLKSEL_SHIFT)
+#define USBPCR1_REFCLKSEL_CORE	(0x2 << USBPCR1_REFCLKSEL_SHIFT)
+#define USBPCR1_REFCLKDIV_SHIFT	24
+#define USBPCR1_REFCLKDIV_MASK	(0x3 << USBPCR1_REFCLKDIV_SHIFT)
+#define USBPCR1_REFCLKDIV_48	(0x2 << USBPCR1_REFCLKDIV_SHIFT)
+#define USBPCR1_REFCLKDIV_24	(0x1 << USBPCR1_REFCLKDIV_SHIFT)
+#define USBPCR1_REFCLKDIV_12	(0x0 << USBPCR1_REFCLKDIV_SHIFT)
+
 static struct ingenic_cgu *cgu;
 
+static unsigned long x1000_otg_phy_recalc_rate(struct clk_hw *hw,
+						unsigned long parent_rate)
+{
+	u32 usbpcr1;
+	unsigned refclk_div;
+
+	usbpcr1 = readl(cgu->base + CGU_REG_USBPCR1);
+	refclk_div = usbpcr1 & USBPCR1_REFCLKDIV_MASK;
+
+	switch (refclk_div) {
+	case USBPCR1_REFCLKDIV_12:
+		return 12000000;
+
+	case USBPCR1_REFCLKDIV_24:
+		return 24000000;
+
+	case USBPCR1_REFCLKDIV_48:
+		return 48000000;
+	}
+
+	return parent_rate;
+}
+
+static long x1000_otg_phy_round_rate(struct clk_hw *hw, unsigned long req_rate,
+				      unsigned long *parent_rate)
+{
+	if (req_rate < 18000000)
+		return 12000000;
+
+	if (req_rate < 36000000)
+		return 24000000;
+
+	return 48000000;
+}
+
+static int x1000_otg_phy_set_rate(struct clk_hw *hw, unsigned long req_rate,
+				   unsigned long parent_rate)
+{
+	unsigned long flags;
+	u32 usbpcr1, div_bits;
+
+	switch (req_rate) {
+	case 12000000:
+		div_bits = USBPCR1_REFCLKDIV_12;
+		break;
+
+	case 24000000:
+		div_bits = USBPCR1_REFCLKDIV_24;
+		break;
+
+	case 48000000:
+		div_bits = USBPCR1_REFCLKDIV_48;
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(&cgu->lock, flags);
+
+	usbpcr1 = readl(cgu->base + CGU_REG_USBPCR1);
+	usbpcr1 &= ~USBPCR1_REFCLKDIV_MASK;
+	usbpcr1 |= div_bits;
+	writel(usbpcr1, cgu->base + CGU_REG_USBPCR1);
+
+	spin_unlock_irqrestore(&cgu->lock, flags);
+	return 0;
+}
+
 static int x1000_usb_phy_enable(struct clk_hw *hw)
 {
 	void __iomem *reg_opcr		= cgu->base + CGU_REG_OPCR;
@@ -80,6 +159,10 @@ static int x1000_usb_phy_is_enabled(struct clk_hw *hw)
 }
 
 static const struct clk_ops x1000_otg_phy_ops = {
+	.recalc_rate = x1000_otg_phy_recalc_rate,
+	.round_rate = x1000_otg_phy_round_rate,
+	.set_rate = x1000_otg_phy_set_rate,
+
 	.enable		= x1000_usb_phy_enable,
 	.disable	= x1000_usb_phy_disable,
 	.is_enabled	= x1000_usb_phy_is_enabled,
@@ -144,7 +227,6 @@ static const struct ingenic_cgu_clk_info x1000_cgu_clocks[] = {
 		},
 	},
 
-
 	/* Custom (SoC-specific) OTG PHY */
 
 	[X1000_CLK_OTGPHY] = {