[PATCH v3 2/5] clk: samsung: clk-pll: Implement pll0831x PLL type

Sam Protsenko
2021-10-08T15:44:14Z

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>
---
Changes in v3:
- (none)

Changes in v2:
- Added R-b tag by Krzysztof Kozlowski
- Added Ack tag by Chanwoo Choi

drivers/clk/samsung/clk-pll.c | 105 ++++++++++++++++++++++++++++++++++
drivers/clk/samsung/clk-pll.h | 1 +
2 files changed, 106 insertions(+)

diff --git a/drivers/clk/samsung/clk-pll.c b/drivers/clk/samsung/clk-pll.c
index 03131b149c0b..83d1b03647db 100644
--- a/drivers/clk/samsung/clk-pll.c
+++ b/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;
diff --git a/drivers/clk/samsung/clk-pll.h b/drivers/clk/samsung/clk-pll.h
index 213e94a97f23..a739f2b7ae80 100644
--- a/drivers/clk/samsung/clk-pll.h
+++ b/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) \
--
2.30.2