Re: [PATCH 2/2] clk: X1000: Add support for calculat REFCLK of USB PHY.

From: Paul Cercueil
Date: Mon Jun 29 2020 - 16:46:22 EST

Hi Zhou,

Le lun. 29 juin 2020 Ã 0:18, Zhou Yanjie <zhouyanjie@xxxxxxxxxxxxxx> a Ãcrit :
Hi Paul,

å 2020/6/27 äå1:36, Paul Cercueil åé:
Hi Zhou,

Le sam. 27 juin 2020 Ã 0:48, åçæ (Zhou Yanjie) <zhouyanjie@xxxxxxxxxxxxxx> a Ãcrit :
Add new functions to "x1000_otg_phy_ops" to calculat the rate of REFCLK,
which is needed by USB PHY in the Ingenic X1000 SoC.

Tested-by: åæ (Zhou Zheng) <sernia.zhou@xxxxxxxxxxx>
Signed-off-by: åçæ (Zhou Yanjie) <zhouyanjie@xxxxxxxxxxxxxx>
---
drivers/clk/ingenic/x1000-cgu.c | 113 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 113 insertions(+)

diff --git a/drivers/clk/ingenic/x1000-cgu.c b/drivers/clk/ingenic/x1000-cgu.c
index 453f3323cb99..a61c16f98a11 100644
--- a/drivers/clk/ingenic/x1000-cgu.c
+++ b/drivers/clk/ingenic/x1000-cgu.c
@@ -48,8 +48,114 @@
#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 u8 x1000_otg_phy_get_parent(struct clk_hw *hw)
+{
+ /* we only use CLKCORE, revisit if that ever changes */
+ return 0;
+}
+
+static int x1000_otg_phy_set_parent(struct clk_hw *hw, u8 idx)
+{
+ unsigned long flags;
+ u32 usbpcr1;
+
+ if (idx > 0)
+ return -EINVAL;
+
+ spin_lock_irqsave(&cgu->lock, flags);
+
+ usbpcr1 = readl(cgu->base + CGU_REG_USBPCR1);
+ usbpcr1 &= ~USBPCR1_REFCLKSEL_MASK;
+ /* we only use CLKCORE */
+ usbpcr1 |= USBPCR1_REFCLKSEL_CORE;
+ writel(usbpcr1, cgu->base + CGU_REG_USBPCR1);
+
+ spin_unlock_irqrestore(&cgu->lock, flags);
+ return 0;
+}

If you only support one parent, maybe set that bit in the x1000_cgu_init(), then you can drop the get_parent/set_parent.


Sure.


+
+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;
+ }

On your setup, what frequency is configured for the "otg" clock? Is it 48 MHz?

I believe CLKCORE is the OTG core's clock (aka "otg"), and I'm pretty sure that these fields only represent CLKCORE/4, CLKCORE/2, CLKCORE/1, but the doc expects CLKCORE==48MHz.


This is the REFCLKDIV in USBPCR1 reg, it's for the usb phy, so it is not the otg clock. In X1000 and X1500 it is 24MHz, in JZ4780 it is 48MHz.

I know it is for the OTG PHY clock, what I'm saying is that the OTG PHY clock is derived from CLKCORE which I believe is the "otg" clock. Unless the clock represents a crystal, it is derived from another clock, and as a result the clock rate should be computed from the parent clock rate.

-Paul


In that case the "otg_phy" should be parented to "otg", and the rate should be computed according to the parent rate and the divider configured.

+
+ BUG();

Don't use BUG() - it pisses off Linus :)
And it's reserved for bugs that will take the whole system down, I think. Better use WARN().


Sure, I will change it in the next version.

Thanks and best regards!


Cheers,
-Paul

+ 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 +186,13 @@ static int x1000_usb_phy_is_enabled(struct clk_hw *hw)
}

static const struct clk_ops x1000_otg_phy_ops = {
+ .get_parent = x1000_otg_phy_get_parent,
+ .set_parent = x1000_otg_phy_set_parent,
+
+ .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,
--
2.11.0