clk: samsung: clk-pll: Implement pll0831x PLL type

pll0831x PLL is used in Exynos850 SoC for top-level fractional PLLs. The
code was derived from very similar pll36xx type, with next differences:

1. Lock time for pll0831x is 500*P_DIV, when for pll36xx it's 3000*P_DIV
2. It's not suggested in Exynos850 TRM that S_DIV change doesn't require
   performing PLL lock procedure (which is done in pll36xx
   implementation)
3. The offset from PMS-values register to K-value register is 0x8 for
   pll0831x, when for pll36xx it's 0x4

When defining pll0831x type, CON3 register offset should be provided as
a "con" parameter of PLL() macro, like this:

    PLL(pll_0831x, 0, "fout_mmc_pll", "oscclk",
        PLL_LOCKTIME_PLL_MMC, PLL_CON3_PLL_MMC, pll0831x_26mhz_tbl),

To define PLL rates table, one can use PLL_36XX_RATE() macro, e.g.:

    PLL_36XX_RATE(26 * MHZ, 799999877, 31, 1, 0, -15124)

as it's completely appropriate for pl0831x type and there is no sense in
duplicating that.

If bit #1 (MANUAL_PLL_CTRL) is not set in CON1 register, it won't be
possible to set new rate, with next error showing in kernel log:

    Could not lock PLL fout_mmc_pll

That can happen for example if bootloader clears that bit beforehand.
PLL driver doesn't account for that, so if MANUAL_PLL_CTRL bit was
cleared, it's assumed it was done for a reason and it shouldn't be
possible to change that PLL's rate at all.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Link: https://lore.kernel.org/r/20211008154352.19519-3-semen.protsenko@linaro.org
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>

drivers/clk/samsung/clk-pll.c

@@ -498,6 +498,103 @@ static const struct clk_ops samsung_pll0822x_clk_min_ops = {
 	.recalc_rate = samsung_pll0822x_recalc_rate,
 };
 
+/*
+ * PLL0831x Clock Type
+ */
+/* Maximum lock time can be 500 * PDIV cycles */
+#define PLL0831X_LOCK_FACTOR		(500)
+
+#define PLL0831X_KDIV_MASK		(0xFFFF)
+#define PLL0831X_MDIV_MASK		(0x1FF)
+#define PLL0831X_PDIV_MASK		(0x3F)
+#define PLL0831X_SDIV_MASK		(0x7)
+#define PLL0831X_MDIV_SHIFT		(16)
+#define PLL0831X_PDIV_SHIFT		(8)
+#define PLL0831X_SDIV_SHIFT		(0)
+#define PLL0831X_KDIV_SHIFT		(0)
+#define PLL0831X_LOCK_STAT_SHIFT	(29)
+#define PLL0831X_ENABLE_SHIFT		(31)
+
+static unsigned long samsung_pll0831x_recalc_rate(struct clk_hw *hw,
+						  unsigned long parent_rate)
+{
+	struct samsung_clk_pll *pll = to_clk_pll(hw);
+	u32 mdiv, pdiv, sdiv, pll_con3, pll_con5;
+	s16 kdiv;
+	u64 fvco = parent_rate;
+
+	pll_con3 = readl_relaxed(pll->con_reg);
+	pll_con5 = readl_relaxed(pll->con_reg + 8);
+	mdiv = (pll_con3 >> PLL0831X_MDIV_SHIFT) & PLL0831X_MDIV_MASK;
+	pdiv = (pll_con3 >> PLL0831X_PDIV_SHIFT) & PLL0831X_PDIV_MASK;
+	sdiv = (pll_con3 >> PLL0831X_SDIV_SHIFT) & PLL0831X_SDIV_MASK;
+	kdiv = (s16)((pll_con5 >> PLL0831X_KDIV_SHIFT) & PLL0831X_KDIV_MASK);
+
+	fvco *= (mdiv << 16) + kdiv;
+	do_div(fvco, (pdiv << sdiv));
+	fvco >>= 16;
+
+	return (unsigned long)fvco;
+}
+
+static int samsung_pll0831x_set_rate(struct clk_hw *hw, unsigned long drate,
+				     unsigned long parent_rate)
+{
+	const struct samsung_pll_rate_table *rate;
+	struct samsung_clk_pll *pll = to_clk_pll(hw);
+	u32 pll_con3, pll_con5;
+
+	/* Get required rate settings from table */
+	rate = samsung_get_pll_settings(pll, drate);
+	if (!rate) {
+		pr_err("%s: Invalid rate : %lu for pll clk %s\n", __func__,
+			drate, clk_hw_get_name(hw));
+		return -EINVAL;
+	}
+
+	pll_con3 = readl_relaxed(pll->con_reg);
+	pll_con5 = readl_relaxed(pll->con_reg + 8);
+
+	/* Change PLL PMSK values */
+	pll_con3 &= ~((PLL0831X_MDIV_MASK << PLL0831X_MDIV_SHIFT) |
+			(PLL0831X_PDIV_MASK << PLL0831X_PDIV_SHIFT) |
+			(PLL0831X_SDIV_MASK << PLL0831X_SDIV_SHIFT));
+	pll_con3 |= (rate->mdiv << PLL0831X_MDIV_SHIFT) |
+			(rate->pdiv << PLL0831X_PDIV_SHIFT) |
+			(rate->sdiv << PLL0831X_SDIV_SHIFT);
+	pll_con5 &= ~(PLL0831X_KDIV_MASK << PLL0831X_KDIV_SHIFT);
+	/*
+	 * kdiv is 16-bit 2's complement (s16), but stored as unsigned int.
+	 * Cast it to u16 to avoid leading 0xffff's in case of negative value.
+	 */
+	pll_con5 |= ((u16)rate->kdiv << PLL0831X_KDIV_SHIFT);
+
+	/* Set PLL lock time */
+	writel_relaxed(rate->pdiv * PLL0831X_LOCK_FACTOR, pll->lock_reg);
+
+	/* Write PMSK values */
+	writel_relaxed(pll_con3, pll->con_reg);
+	writel_relaxed(pll_con5, pll->con_reg + 8);
+
+	/* Wait for PLL lock if the PLL is enabled */
+	if (pll_con3 & BIT(pll->enable_offs))
+		return samsung_pll_lock_wait(pll, BIT(pll->lock_offs));
+
+	return 0;
+}
+
+static const struct clk_ops samsung_pll0831x_clk_ops = {
+	.recalc_rate = samsung_pll0831x_recalc_rate,
+	.set_rate = samsung_pll0831x_set_rate,
+	.round_rate = samsung_pll_round_rate,
+	.enable = samsung_pll3xxx_enable,
+	.disable = samsung_pll3xxx_disable,
+};
+
+static const struct clk_ops samsung_pll0831x_clk_min_ops = {
+	.recalc_rate = samsung_pll0831x_recalc_rate,
+};
+
 /*
  * PLL45xx Clock Type
  */
@@ -1407,6 +1504,14 @@ static void __init _samsung_clk_register_pll(struct samsung_clk_provider *ctx,
 		else
 			init.ops = &samsung_pll36xx_clk_ops;
 		break;
+	case pll_0831x:
+		pll->enable_offs = PLL0831X_ENABLE_SHIFT;
+		pll->lock_offs = PLL0831X_LOCK_STAT_SHIFT;
+		if (!pll->rate_table)
+			init.ops = &samsung_pll0831x_clk_min_ops;
+		else
+			init.ops = &samsung_pll0831x_clk_ops;
+		break;
 	case pll_6552:
 	case pll_6552_s3c2416:
 		init.ops = &samsung_pll6552_clk_ops;

drivers/clk/samsung/clk-pll.h

@@ -37,6 +37,7 @@ enum samsung_pll_type {
 	pll_1452x,
 	pll_1460x,
 	pll_0822x,
+	pll_0831x,
 };
 
 #define PLL_RATE(_fin, _m, _p, _s, _k, _ks) \