clk: k210: Move pll into the rest of the driver
Now that there no separate PLL driver, we can no longer make the PLL
functions static. By moving the PLL driver in with the rest of the clock
code, we can make these functions static again. We still keep the pll
header for unit testing, but it is pretty reduced.
Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
diff --git a/drivers/clk/kendryte/Makefile b/drivers/clk/kendryte/Makefile
index 6fb6825..6710a1d 100644
--- a/drivers/clk/kendryte/Makefile
+++ b/drivers/clk/kendryte/Makefile
@@ -1 +1 @@
-obj-y += bypass.o clk.o pll.o
+obj-y += bypass.o clk.o
diff --git a/drivers/clk/kendryte/clk.c b/drivers/clk/kendryte/clk.c
index 34e8e74..de9db84 100644
--- a/drivers/clk/kendryte/clk.c
+++ b/drivers/clk/kendryte/clk.c
@@ -2,17 +2,30 @@
/*
* Copyright (C) 2019-20 Sean Anderson <seanga2@gmail.com>
*/
-#include <kendryte/clk.h>
+#define LOG_CATEGORY UCLASS_CLK
#include <common.h>
-#include <dt-bindings/clock/k210-sysctl.h>
-#include <dt-bindings/mfd/k210-sysctl.h>
+#include <clk.h>
+#include <clk-uclass.h>
+#include <div64.h>
#include <dm.h>
#include <log.h>
#include <mapmem.h>
-
-#include <kendryte/bypass.h>
+#include <serial.h>
+#include <dt-bindings/clock/k210-sysctl.h>
+#include <dt-bindings/mfd/k210-sysctl.h>
#include <kendryte/pll.h>
+#include <linux/bitfield.h>
+
+/**
+ * struct k210_clk_priv - K210 clock driver private data
+ * @base: The base address of the sysctl device
+ * @in0: The "in0" external oscillator
+ */
+struct k210_clk_priv {
+ void __iomem *base;
+ struct clk in0;
+};
/*
* All parameters for different sub-clocks are collected into parameter arrays.
@@ -249,6 +262,30 @@
#undef MUX_LIST
/**
+ * struct k210_pll_params - K210 PLL parameters
+ * @off: The offset of the PLL from the base sysctl address
+ * @shift: The offset of the LSB of the lock status
+ * @width: The number of bits in the lock status
+ */
+struct k210_pll_params {
+ u8 off;
+ u8 shift;
+ u8 width;
+};
+
+static const struct k210_pll_params k210_plls[] = {
+#define PLL(_off, _shift, _width) { \
+ .off = (_off), \
+ .shift = (_shift), \
+ .width = (_width), \
+}
+ [0] = PLL(K210_SYSCTL_PLL0, 0, 2),
+ [1] = PLL(K210_SYSCTL_PLL1, 8, 1),
+ [2] = PLL(K210_SYSCTL_PLL2, 16, 1),
+#undef PLL
+};
+
+/**
* enum k210_clk_flags - The type of a K210 clock
* @K210_CLKF_MUX: This clock has a mux and not a static parent
* @K210_CLKF_PLL: This clock is a PLL
@@ -286,7 +323,6 @@
};
};
-
static const struct k210_clk_params k210_clks[] = {
#if CONFIG_IS_ENABLED(CMD_CLK)
#define NAME(_name) .name = (_name),
@@ -382,6 +418,564 @@
#undef CLK_LIST
};
+#define K210_PLL_CLKR GENMASK(3, 0)
+#define K210_PLL_CLKF GENMASK(9, 4)
+#define K210_PLL_CLKOD GENMASK(13, 10) /* Output Divider */
+#define K210_PLL_BWADJ GENMASK(19, 14) /* BandWidth Adjust */
+#define K210_PLL_RESET BIT(20)
+#define K210_PLL_PWRD BIT(21) /* PoWeReD */
+#define K210_PLL_INTFB BIT(22) /* Internal FeedBack */
+#define K210_PLL_BYPASS BIT(23)
+#define K210_PLL_TEST BIT(24)
+#define K210_PLL_EN BIT(25)
+#define K210_PLL_TEST_EN BIT(26)
+
+#define K210_PLL_LOCK 0
+#define K210_PLL_CLEAR_SLIP 2
+#define K210_PLL_TEST_OUT 3
+
+#ifdef CONFIG_CLK_K210_SET_RATE
+static int k210_pll_enable(struct k210_clk_priv *priv, int id);
+static int k210_pll_disable(struct k210_clk_priv *priv, int id);
+static ulong k210_pll_get_rate(struct k210_clk_priv *priv, int id, ulong rate_in);
+
+/*
+ * The PLL included with the Kendryte K210 appears to be a True Circuits, Inc.
+ * General-Purpose PLL. The logical layout of the PLL with internal feedback is
+ * approximately the following:
+ *
+ * +---------------+
+ * |reference clock|
+ * +---------------+
+ * |
+ * v
+ * +--+
+ * |/r|
+ * +--+
+ * |
+ * v
+ * +-------------+
+ * |divided clock|
+ * +-------------+
+ * |
+ * v
+ * +--------------+
+ * |phase detector|<---+
+ * +--------------+ |
+ * | |
+ * v +--------------+
+ * +---+ |feedback clock|
+ * |VCO| +--------------+
+ * +---+ ^
+ * | +--+ |
+ * +--->|/f|---+
+ * | +--+
+ * v
+ * +---+
+ * |/od|
+ * +---+
+ * |
+ * v
+ * +------+
+ * |output|
+ * +------+
+ *
+ * The k210 PLLs have three factors: r, f, and od. Because of the feedback mode,
+ * the effect of the division by f is to multiply the input frequency. The
+ * equation for the output rate is
+ * rate = (rate_in * f) / (r * od).
+ * Moving knowns to one side of the equation, we get
+ * rate / rate_in = f / (r * od)
+ * Rearranging slightly,
+ * abs_error = abs((rate / rate_in) - (f / (r * od))).
+ * To get relative, error, we divide by the expected ratio
+ * error = abs((rate / rate_in) - (f / (r * od))) / (rate / rate_in).
+ * Simplifying,
+ * error = abs(1 - f / (r * od)) / (rate / rate_in)
+ * error = abs(1 - (f * rate_in) / (r * od * rate))
+ * Using the constants ratio = rate / rate_in and inv_ratio = rate_in / rate,
+ * error = abs((f * inv_ratio) / (r * od) - 1)
+ * This is the error used in evaluating parameters.
+ *
+ * r and od are four bits each, while f is six bits. Because r and od are
+ * multiplied together, instead of the full 256 values possible if both bits
+ * were used fully, there are only 97 distinct products. Combined with f, there
+ * are 6208 theoretical settings for the PLL. However, most of these settings
+ * can be ruled out immediately because they do not have the correct ratio.
+ *
+ * In addition to the constraint of approximating the desired ratio, parameters
+ * must also keep internal pll frequencies within acceptable ranges. The divided
+ * clock's minimum and maximum frequencies have a ratio of around 128. This
+ * leaves fairly substantial room to work with, especially since the only
+ * affected parameter is r. The VCO's minimum and maximum frequency have a ratio
+ * of 5, which is considerably more restrictive.
+ *
+ * The r and od factors are stored in a table. This is to make it easy to find
+ * the next-largest product. Some products have multiple factorizations, but
+ * only when one factor has at least a 2.5x ratio to the factors of the other
+ * factorization. This is because any smaller ratio would not make a difference
+ * when ensuring the VCO's frequency is within spec.
+ *
+ * Throughout the calculation function, fixed point arithmetic is used. Because
+ * the range of rate and rate_in may be up to 1.75 GHz, or around 2^30, 64-bit
+ * 32.32 fixed-point numbers are used to represent ratios. In general, to
+ * implement division, the numerator is first multiplied by 2^32. This gives a
+ * result where the whole number part is in the upper 32 bits, and the fraction
+ * is in the lower 32 bits.
+ *
+ * In general, rounding is done to the closest integer. This helps find the best
+ * approximation for the ratio. Rounding in one direction (e.g down) could cause
+ * the function to miss a better ratio with one of the parameters increased by
+ * one.
+ */
+
+/*
+ * The factors table was generated with the following python code:
+ *
+ * def p(x, y):
+ * return (1.0*x/y > 2.5) or (1.0*y/x > 2.5)
+ *
+ * factors = {}
+ * for i in range(1, 17):
+ * for j in range(1, 17):
+ * fs = factors.get(i*j) or []
+ * if fs == [] or all([
+ * (p(i, x) and p(i, y)) or (p(j, x) and p(j, y))
+ * for (x, y) in fs]):
+ * fs.append((i, j))
+ * factors[i*j] = fs
+ *
+ * for k, l in sorted(factors.items()):
+ * for v in l:
+ * print("PACK(%s, %s)," % v)
+ */
+#define PACK(r, od) (((((r) - 1) & 0xF) << 4) | (((od) - 1) & 0xF))
+#define UNPACK_R(val) ((((val) >> 4) & 0xF) + 1)
+#define UNPACK_OD(val) (((val) & 0xF) + 1)
+static const u8 factors[] = {
+ PACK(1, 1),
+ PACK(1, 2),
+ PACK(1, 3),
+ PACK(1, 4),
+ PACK(1, 5),
+ PACK(1, 6),
+ PACK(1, 7),
+ PACK(1, 8),
+ PACK(1, 9),
+ PACK(3, 3),
+ PACK(1, 10),
+ PACK(1, 11),
+ PACK(1, 12),
+ PACK(3, 4),
+ PACK(1, 13),
+ PACK(1, 14),
+ PACK(1, 15),
+ PACK(3, 5),
+ PACK(1, 16),
+ PACK(4, 4),
+ PACK(2, 9),
+ PACK(2, 10),
+ PACK(3, 7),
+ PACK(2, 11),
+ PACK(2, 12),
+ PACK(5, 5),
+ PACK(2, 13),
+ PACK(3, 9),
+ PACK(2, 14),
+ PACK(2, 15),
+ PACK(2, 16),
+ PACK(3, 11),
+ PACK(5, 7),
+ PACK(3, 12),
+ PACK(3, 13),
+ PACK(4, 10),
+ PACK(3, 14),
+ PACK(4, 11),
+ PACK(3, 15),
+ PACK(3, 16),
+ PACK(7, 7),
+ PACK(5, 10),
+ PACK(4, 13),
+ PACK(6, 9),
+ PACK(5, 11),
+ PACK(4, 14),
+ PACK(4, 15),
+ PACK(7, 9),
+ PACK(4, 16),
+ PACK(5, 13),
+ PACK(6, 11),
+ PACK(5, 14),
+ PACK(6, 12),
+ PACK(5, 15),
+ PACK(7, 11),
+ PACK(6, 13),
+ PACK(5, 16),
+ PACK(9, 9),
+ PACK(6, 14),
+ PACK(8, 11),
+ PACK(6, 15),
+ PACK(7, 13),
+ PACK(6, 16),
+ PACK(7, 14),
+ PACK(9, 11),
+ PACK(10, 10),
+ PACK(8, 13),
+ PACK(7, 15),
+ PACK(9, 12),
+ PACK(10, 11),
+ PACK(7, 16),
+ PACK(9, 13),
+ PACK(8, 15),
+ PACK(11, 11),
+ PACK(9, 14),
+ PACK(8, 16),
+ PACK(10, 13),
+ PACK(11, 12),
+ PACK(9, 15),
+ PACK(10, 14),
+ PACK(11, 13),
+ PACK(9, 16),
+ PACK(10, 15),
+ PACK(11, 14),
+ PACK(12, 13),
+ PACK(10, 16),
+ PACK(11, 15),
+ PACK(12, 14),
+ PACK(13, 13),
+ PACK(11, 16),
+ PACK(12, 15),
+ PACK(13, 14),
+ PACK(12, 16),
+ PACK(13, 15),
+ PACK(14, 14),
+ PACK(13, 16),
+ PACK(14, 15),
+ PACK(14, 16),
+ PACK(15, 15),
+ PACK(15, 16),
+ PACK(16, 16),
+};
+
+TEST_STATIC int k210_pll_calc_config(u32 rate, u32 rate_in,
+ struct k210_pll_config *best)
+{
+ int i;
+ s64 error, best_error;
+ u64 ratio, inv_ratio; /* fixed point 32.32 ratio of the rates */
+ u64 max_r;
+ u64 r, f, od;
+
+ /*
+ * Can't go over 1.75 GHz or under 21.25 MHz due to limitations on the
+ * VCO frequency. These are not the same limits as below because od can
+ * reduce the output frequency by 16.
+ */
+ if (rate > 1750000000 || rate < 21250000)
+ return -EINVAL;
+
+ /* Similar restrictions on the input rate */
+ if (rate_in > 1750000000 || rate_in < 13300000)
+ return -EINVAL;
+
+ ratio = DIV_ROUND_CLOSEST_ULL((u64)rate << 32, rate_in);
+ inv_ratio = DIV_ROUND_CLOSEST_ULL((u64)rate_in << 32, rate);
+ /* Can't increase by more than 64 or reduce by more than 256 */
+ if (rate > rate_in && ratio > (64ULL << 32))
+ return -EINVAL;
+ else if (rate <= rate_in && inv_ratio > (256ULL << 32))
+ return -EINVAL;
+
+ /*
+ * The divided clock (rate_in / r) must stay between 1.75 GHz and 13.3
+ * MHz. There is no minimum, since the only way to get a higher input
+ * clock than 26 MHz is to use a clock generated by a PLL. Because PLLs
+ * cannot output frequencies greater than 1.75 GHz, the minimum would
+ * never be greater than one.
+ */
+ max_r = DIV_ROUND_DOWN_ULL(rate_in, 13300000);
+
+ /* Variables get immediately incremented, so start at -1th iteration */
+ i = -1;
+ f = 0;
+ r = 0;
+ od = 0;
+ best_error = S64_MAX;
+ error = best_error;
+ /* do-while here so we always try at least one ratio */
+ do {
+ /*
+ * Whether we swapped r and od while enforcing frequency limits
+ */
+ bool swapped = false;
+ u64 last_od = od;
+ u64 last_r = r;
+
+ /*
+ * Try the next largest value for f (or r and od) and
+ * recalculate the other parameters based on that
+ */
+ if (rate > rate_in) {
+ /*
+ * Skip factors of the same product if we already tried
+ * out that product
+ */
+ do {
+ i++;
+ r = UNPACK_R(factors[i]);
+ od = UNPACK_OD(factors[i]);
+ } while (i + 1 < ARRAY_SIZE(factors) &&
+ r * od == last_r * last_od);
+
+ /* Round close */
+ f = (r * od * ratio + BIT(31)) >> 32;
+ if (f > 64)
+ f = 64;
+ } else {
+ u64 tmp = ++f * inv_ratio;
+ bool round_up = !!(tmp & BIT(31));
+ u32 goal = (tmp >> 32) + round_up;
+ u32 err, last_err;
+
+ /* Get the next r/od pair in factors */
+ while (r * od < goal && i + 1 < ARRAY_SIZE(factors)) {
+ i++;
+ r = UNPACK_R(factors[i]);
+ od = UNPACK_OD(factors[i]);
+ }
+
+ /*
+ * This is a case of double rounding. If we rounded up
+ * above, we need to round down (in cases of ties) here.
+ * This prevents off-by-one errors resulting from
+ * choosing X+2 over X when X.Y rounds up to X+1 and
+ * there is no r * od = X+1. For the converse, when X.Y
+ * is rounded down to X, we should choose X+1 over X-1.
+ */
+ err = abs(r * od - goal);
+ last_err = abs(last_r * last_od - goal);
+ if (last_err < err || (round_up && last_err == err)) {
+ i--;
+ r = last_r;
+ od = last_od;
+ }
+ }
+
+ /*
+ * Enforce limits on internal clock frequencies. If we
+ * aren't in spec, try swapping r and od. If everything is
+ * in-spec, calculate the relative error.
+ */
+ while (true) {
+ /*
+ * Whether the intermediate frequencies are out-of-spec
+ */
+ bool out_of_spec = false;
+
+ if (r > max_r) {
+ out_of_spec = true;
+ } else {
+ /*
+ * There is no way to only divide once; we need
+ * to examine the frequency with and without the
+ * effect of od.
+ */
+ u64 vco = DIV_ROUND_CLOSEST_ULL(rate_in * f, r);
+
+ if (vco > 1750000000 || vco < 340000000)
+ out_of_spec = true;
+ }
+
+ if (out_of_spec) {
+ if (!swapped) {
+ u64 tmp = r;
+
+ r = od;
+ od = tmp;
+ swapped = true;
+ continue;
+ } else {
+ /*
+ * Try looking ahead to see if there are
+ * additional factors for the same
+ * product.
+ */
+ if (i + 1 < ARRAY_SIZE(factors)) {
+ u64 new_r, new_od;
+
+ i++;
+ new_r = UNPACK_R(factors[i]);
+ new_od = UNPACK_OD(factors[i]);
+ if (r * od == new_r * new_od) {
+ r = new_r;
+ od = new_od;
+ swapped = false;
+ continue;
+ }
+ i--;
+ }
+ break;
+ }
+ }
+
+ error = DIV_ROUND_CLOSEST_ULL(f * inv_ratio, r * od);
+ /* The lower 16 bits are spurious */
+ error = abs((error - BIT(32))) >> 16;
+
+ if (error < best_error) {
+ best->r = r;
+ best->f = f;
+ best->od = od;
+ best_error = error;
+ }
+ break;
+ }
+ } while (f < 64 && i + 1 < ARRAY_SIZE(factors) && error != 0);
+
+ if (best_error == S64_MAX)
+ return -EINVAL;
+
+ log_debug("best error %lld\n", best_error);
+ return 0;
+}
+
+static ulong k210_pll_set_rate(struct k210_clk_priv *priv, int id, ulong rate,
+ ulong rate_in)
+{
+ int err;
+ const struct k210_pll_params *pll = &k210_plls[id];
+ struct k210_pll_config config = {};
+ u32 reg;
+
+ if (rate_in < 0)
+ return rate_in;
+
+ log_debug("Calculating parameters with rate=%lu and rate_in=%lu\n",
+ rate, rate_in);
+ err = k210_pll_calc_config(rate, rate_in, &config);
+ if (err)
+ return err;
+ log_debug("Got r=%u f=%u od=%u\n", config.r, config.f, config.od);
+
+ /*
+ * Don't use clk_disable as it might not actually disable the pll due to
+ * refcounting
+ */
+ k210_pll_disable(priv, id);
+
+ reg = readl(priv->base + pll->off);
+ reg &= ~K210_PLL_CLKR
+ & ~K210_PLL_CLKF
+ & ~K210_PLL_CLKOD
+ & ~K210_PLL_BWADJ;
+ reg |= FIELD_PREP(K210_PLL_CLKR, config.r - 1)
+ | FIELD_PREP(K210_PLL_CLKF, config.f - 1)
+ | FIELD_PREP(K210_PLL_CLKOD, config.od - 1)
+ | FIELD_PREP(K210_PLL_BWADJ, config.f - 1);
+ writel(reg, priv->base + pll->off);
+
+ err = k210_pll_enable(priv, id);
+
+ serial_setbrg();
+ return k210_pll_get_rate(priv, id, rate);
+}
+#else
+static ulong k210_pll_set_rate(struct k210_clk_priv *priv, int id, ulong rate,
+ ulong rate_in)
+{
+ return -ENOSYS;
+}
+#endif /* CONFIG_CLK_K210_SET_RATE */
+
+static ulong k210_pll_get_rate(struct k210_clk_priv *priv, int id,
+ ulong rate_in)
+{
+ u64 r, f, od;
+ u32 reg = readl(priv->base + k210_plls[id].off);
+
+ if (rate_in < 0 || (reg & K210_PLL_BYPASS))
+ return rate_in;
+
+ if (!(reg & K210_PLL_PWRD))
+ return 0;
+
+ r = FIELD_GET(K210_PLL_CLKR, reg) + 1;
+ f = FIELD_GET(K210_PLL_CLKF, reg) + 1;
+ od = FIELD_GET(K210_PLL_CLKOD, reg) + 1;
+
+ return DIV_ROUND_DOWN_ULL(((u64)rate_in) * f, r * od);
+}
+
+/*
+ * Wait for the PLL to be locked. If the PLL is not locked, try clearing the
+ * slip before retrying
+ */
+static void k210_pll_waitfor_lock(struct k210_clk_priv *priv, int id)
+{
+ const struct k210_pll_params *pll = &k210_plls[id];
+ u32 mask = (BIT(pll->width) - 1) << pll->shift;
+
+ while (true) {
+ u32 reg = readl(priv->base + K210_SYSCTL_PLL_LOCK);
+
+ if ((reg & mask) == mask)
+ break;
+
+ reg |= BIT(pll->shift + K210_PLL_CLEAR_SLIP);
+ writel(reg, priv->base + K210_SYSCTL_PLL_LOCK);
+ }
+}
+
+/* Adapted from sysctl_pll_enable */
+static int k210_pll_enable(struct k210_clk_priv *priv, int id)
+{
+ const struct k210_pll_params *pll = &k210_plls[id];
+ u32 reg = readl(priv->base + pll->off);
+
+ if ((reg & K210_PLL_PWRD) && (reg & K210_PLL_EN) &&
+ !(reg & K210_PLL_RESET))
+ return 0;
+
+ reg |= K210_PLL_PWRD;
+ writel(reg, priv->base + pll->off);
+
+ /* Ensure reset is low before asserting it */
+ reg &= ~K210_PLL_RESET;
+ writel(reg, priv->base + pll->off);
+ reg |= K210_PLL_RESET;
+ writel(reg, priv->base + pll->off);
+ nop();
+ nop();
+ reg &= ~K210_PLL_RESET;
+ writel(reg, priv->base + pll->off);
+
+ k210_pll_waitfor_lock(priv, id);
+
+ reg &= ~K210_PLL_BYPASS;
+ reg |= K210_PLL_EN;
+ writel(reg, priv->base + pll->off);
+
+ return 0;
+}
+
+static int k210_pll_disable(struct k210_clk_priv *priv, int id)
+{
+ const struct k210_pll_params *pll = &k210_plls[id];
+ u32 reg = readl(priv->base + pll->off);
+
+ /*
+ * Bypassing before powering off is important so child clocks don't stop
+ * working. This is especially important for pll0, the indirect parent
+ * of the cpu clock.
+ */
+ reg |= K210_PLL_BYPASS;
+ writel(reg, priv->base + pll->off);
+
+ reg &= ~K210_PLL_PWRD;
+ reg &= ~K210_PLL_EN;
+ writel(reg, priv->base + pll->off);
+ return 0;
+}
+
static u32 k210_clk_readl(struct k210_clk_priv *priv, u8 off, u8 shift,
u8 width)
{
diff --git a/drivers/clk/kendryte/pll.c b/drivers/clk/kendryte/pll.c
deleted file mode 100644
index 1f0275c..0000000
--- a/drivers/clk/kendryte/pll.c
+++ /dev/null
@@ -1,587 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0+
-/*
- * Copyright (C) 2019-20 Sean Anderson <seanga2@gmail.com>
- */
-#define LOG_CATEGORY UCLASS_CLK
-
-#include <common.h>
-#include <dm.h>
-/* For DIV_ROUND_DOWN_ULL, defined in linux/kernel.h */
-#include <div64.h>
-#include <log.h>
-#include <serial.h>
-#include <asm/io.h>
-#include <dt-bindings/clock/k210-sysctl.h>
-#include <dt-bindings/mfd/k210-sysctl.h>
-#include <kendryte/pll.h>
-#include <linux/bitfield.h>
-#include <linux/clk-provider.h>
-#include <linux/delay.h>
-#include <linux/err.h>
-
-/**
- * struct k210_pll_params - K210 PLL parameters
- * @off: The offset of the PLL from the base sysctl address
- * @shift: The offset of the LSB of the lock status
- * @width: The number of bits in the lock status
- */
-struct k210_pll_params {
- u8 off;
- u8 shift;
- u8 width;
-};
-
-static const struct k210_pll_params k210_plls[] = {
-#define PLL(_off, _shift, _width) { \
- .off = (_off), \
- .shift = (_shift), \
- .width = (_width), \
-}
- [0] = PLL(K210_SYSCTL_PLL0, 0, 2),
- [1] = PLL(K210_SYSCTL_PLL1, 8, 1),
- [2] = PLL(K210_SYSCTL_PLL2, 16, 1),
-#undef PLL
-};
-
-#ifdef CONFIG_CLK_K210_SET_RATE
-int k210_pll_enable(struct k210_clk_priv *priv, int id);
-int k210_pll_disable(struct k210_clk_priv *priv, int id);
-ulong k210_pll_get_rate(struct k210_clk_priv *priv, int id, ulong rate_in);
-
-/*
- * The PLL included with the Kendryte K210 appears to be a True Circuits, Inc.
- * General-Purpose PLL. The logical layout of the PLL with internal feedback is
- * approximately the following:
- *
- * +---------------+
- * |reference clock|
- * +---------------+
- * |
- * v
- * +--+
- * |/r|
- * +--+
- * |
- * v
- * +-------------+
- * |divided clock|
- * +-------------+
- * |
- * v
- * +--------------+
- * |phase detector|<---+
- * +--------------+ |
- * | |
- * v +--------------+
- * +---+ |feedback clock|
- * |VCO| +--------------+
- * +---+ ^
- * | +--+ |
- * +--->|/f|---+
- * | +--+
- * v
- * +---+
- * |/od|
- * +---+
- * |
- * v
- * +------+
- * |output|
- * +------+
- *
- * The k210 PLLs have three factors: r, f, and od. Because of the feedback mode,
- * the effect of the division by f is to multiply the input frequency. The
- * equation for the output rate is
- * rate = (rate_in * f) / (r * od).
- * Moving knowns to one side of the equation, we get
- * rate / rate_in = f / (r * od)
- * Rearranging slightly,
- * abs_error = abs((rate / rate_in) - (f / (r * od))).
- * To get relative, error, we divide by the expected ratio
- * error = abs((rate / rate_in) - (f / (r * od))) / (rate / rate_in).
- * Simplifying,
- * error = abs(1 - f / (r * od)) / (rate / rate_in)
- * error = abs(1 - (f * rate_in) / (r * od * rate))
- * Using the constants ratio = rate / rate_in and inv_ratio = rate_in / rate,
- * error = abs((f * inv_ratio) / (r * od) - 1)
- * This is the error used in evaluating parameters.
- *
- * r and od are four bits each, while f is six bits. Because r and od are
- * multiplied together, instead of the full 256 values possible if both bits
- * were used fully, there are only 97 distinct products. Combined with f, there
- * are 6208 theoretical settings for the PLL. However, most of these settings
- * can be ruled out immediately because they do not have the correct ratio.
- *
- * In addition to the constraint of approximating the desired ratio, parameters
- * must also keep internal pll frequencies within acceptable ranges. The divided
- * clock's minimum and maximum frequencies have a ratio of around 128. This
- * leaves fairly substantial room to work with, especially since the only
- * affected parameter is r. The VCO's minimum and maximum frequency have a ratio
- * of 5, which is considerably more restrictive.
- *
- * The r and od factors are stored in a table. This is to make it easy to find
- * the next-largest product. Some products have multiple factorizations, but
- * only when one factor has at least a 2.5x ratio to the factors of the other
- * factorization. This is because any smaller ratio would not make a difference
- * when ensuring the VCO's frequency is within spec.
- *
- * Throughout the calculation function, fixed point arithmetic is used. Because
- * the range of rate and rate_in may be up to 1.75 GHz, or around 2^30, 64-bit
- * 32.32 fixed-point numbers are used to represent ratios. In general, to
- * implement division, the numerator is first multiplied by 2^32. This gives a
- * result where the whole number part is in the upper 32 bits, and the fraction
- * is in the lower 32 bits.
- *
- * In general, rounding is done to the closest integer. This helps find the best
- * approximation for the ratio. Rounding in one direction (e.g down) could cause
- * the function to miss a better ratio with one of the parameters increased by
- * one.
- */
-
-/*
- * The factors table was generated with the following python code:
- *
- * def p(x, y):
- * return (1.0*x/y > 2.5) or (1.0*y/x > 2.5)
- *
- * factors = {}
- * for i in range(1, 17):
- * for j in range(1, 17):
- * fs = factors.get(i*j) or []
- * if fs == [] or all([
- * (p(i, x) and p(i, y)) or (p(j, x) and p(j, y))
- * for (x, y) in fs]):
- * fs.append((i, j))
- * factors[i*j] = fs
- *
- * for k, l in sorted(factors.items()):
- * for v in l:
- * print("PACK(%s, %s)," % v)
- */
-#define PACK(r, od) (((((r) - 1) & 0xF) << 4) | (((od) - 1) & 0xF))
-#define UNPACK_R(val) ((((val) >> 4) & 0xF) + 1)
-#define UNPACK_OD(val) (((val) & 0xF) + 1)
-static const u8 factors[] = {
- PACK(1, 1),
- PACK(1, 2),
- PACK(1, 3),
- PACK(1, 4),
- PACK(1, 5),
- PACK(1, 6),
- PACK(1, 7),
- PACK(1, 8),
- PACK(1, 9),
- PACK(3, 3),
- PACK(1, 10),
- PACK(1, 11),
- PACK(1, 12),
- PACK(3, 4),
- PACK(1, 13),
- PACK(1, 14),
- PACK(1, 15),
- PACK(3, 5),
- PACK(1, 16),
- PACK(4, 4),
- PACK(2, 9),
- PACK(2, 10),
- PACK(3, 7),
- PACK(2, 11),
- PACK(2, 12),
- PACK(5, 5),
- PACK(2, 13),
- PACK(3, 9),
- PACK(2, 14),
- PACK(2, 15),
- PACK(2, 16),
- PACK(3, 11),
- PACK(5, 7),
- PACK(3, 12),
- PACK(3, 13),
- PACK(4, 10),
- PACK(3, 14),
- PACK(4, 11),
- PACK(3, 15),
- PACK(3, 16),
- PACK(7, 7),
- PACK(5, 10),
- PACK(4, 13),
- PACK(6, 9),
- PACK(5, 11),
- PACK(4, 14),
- PACK(4, 15),
- PACK(7, 9),
- PACK(4, 16),
- PACK(5, 13),
- PACK(6, 11),
- PACK(5, 14),
- PACK(6, 12),
- PACK(5, 15),
- PACK(7, 11),
- PACK(6, 13),
- PACK(5, 16),
- PACK(9, 9),
- PACK(6, 14),
- PACK(8, 11),
- PACK(6, 15),
- PACK(7, 13),
- PACK(6, 16),
- PACK(7, 14),
- PACK(9, 11),
- PACK(10, 10),
- PACK(8, 13),
- PACK(7, 15),
- PACK(9, 12),
- PACK(10, 11),
- PACK(7, 16),
- PACK(9, 13),
- PACK(8, 15),
- PACK(11, 11),
- PACK(9, 14),
- PACK(8, 16),
- PACK(10, 13),
- PACK(11, 12),
- PACK(9, 15),
- PACK(10, 14),
- PACK(11, 13),
- PACK(9, 16),
- PACK(10, 15),
- PACK(11, 14),
- PACK(12, 13),
- PACK(10, 16),
- PACK(11, 15),
- PACK(12, 14),
- PACK(13, 13),
- PACK(11, 16),
- PACK(12, 15),
- PACK(13, 14),
- PACK(12, 16),
- PACK(13, 15),
- PACK(14, 14),
- PACK(13, 16),
- PACK(14, 15),
- PACK(14, 16),
- PACK(15, 15),
- PACK(15, 16),
- PACK(16, 16),
-};
-
-TEST_STATIC int k210_pll_calc_config(u32 rate, u32 rate_in,
- struct k210_pll_config *best)
-{
- int i;
- s64 error, best_error;
- u64 ratio, inv_ratio; /* fixed point 32.32 ratio of the rates */
- u64 max_r;
- u64 r, f, od;
-
- /*
- * Can't go over 1.75 GHz or under 21.25 MHz due to limitations on the
- * VCO frequency. These are not the same limits as below because od can
- * reduce the output frequency by 16.
- */
- if (rate > 1750000000 || rate < 21250000)
- return -EINVAL;
-
- /* Similar restrictions on the input rate */
- if (rate_in > 1750000000 || rate_in < 13300000)
- return -EINVAL;
-
- ratio = DIV_ROUND_CLOSEST_ULL((u64)rate << 32, rate_in);
- inv_ratio = DIV_ROUND_CLOSEST_ULL((u64)rate_in << 32, rate);
- /* Can't increase by more than 64 or reduce by more than 256 */
- if (rate > rate_in && ratio > (64ULL << 32))
- return -EINVAL;
- else if (rate <= rate_in && inv_ratio > (256ULL << 32))
- return -EINVAL;
-
- /*
- * The divided clock (rate_in / r) must stay between 1.75 GHz and 13.3
- * MHz. There is no minimum, since the only way to get a higher input
- * clock than 26 MHz is to use a clock generated by a PLL. Because PLLs
- * cannot output frequencies greater than 1.75 GHz, the minimum would
- * never be greater than one.
- */
- max_r = DIV_ROUND_DOWN_ULL(rate_in, 13300000);
-
- /* Variables get immediately incremented, so start at -1th iteration */
- i = -1;
- f = 0;
- r = 0;
- od = 0;
- best_error = S64_MAX;
- error = best_error;
- /* do-while here so we always try at least one ratio */
- do {
- /*
- * Whether we swapped r and od while enforcing frequency limits
- */
- bool swapped = false;
- u64 last_od = od;
- u64 last_r = r;
-
- /*
- * Try the next largest value for f (or r and od) and
- * recalculate the other parameters based on that
- */
- if (rate > rate_in) {
- /*
- * Skip factors of the same product if we already tried
- * out that product
- */
- do {
- i++;
- r = UNPACK_R(factors[i]);
- od = UNPACK_OD(factors[i]);
- } while (i + 1 < ARRAY_SIZE(factors) &&
- r * od == last_r * last_od);
-
- /* Round close */
- f = (r * od * ratio + BIT(31)) >> 32;
- if (f > 64)
- f = 64;
- } else {
- u64 tmp = ++f * inv_ratio;
- bool round_up = !!(tmp & BIT(31));
- u32 goal = (tmp >> 32) + round_up;
- u32 err, last_err;
-
- /* Get the next r/od pair in factors */
- while (r * od < goal && i + 1 < ARRAY_SIZE(factors)) {
- i++;
- r = UNPACK_R(factors[i]);
- od = UNPACK_OD(factors[i]);
- }
-
- /*
- * This is a case of double rounding. If we rounded up
- * above, we need to round down (in cases of ties) here.
- * This prevents off-by-one errors resulting from
- * choosing X+2 over X when X.Y rounds up to X+1 and
- * there is no r * od = X+1. For the converse, when X.Y
- * is rounded down to X, we should choose X+1 over X-1.
- */
- err = abs(r * od - goal);
- last_err = abs(last_r * last_od - goal);
- if (last_err < err || (round_up && last_err == err)) {
- i--;
- r = last_r;
- od = last_od;
- }
- }
-
- /*
- * Enforce limits on internal clock frequencies. If we
- * aren't in spec, try swapping r and od. If everything is
- * in-spec, calculate the relative error.
- */
- while (true) {
- /*
- * Whether the intermediate frequencies are out-of-spec
- */
- bool out_of_spec = false;
-
- if (r > max_r) {
- out_of_spec = true;
- } else {
- /*
- * There is no way to only divide once; we need
- * to examine the frequency with and without the
- * effect of od.
- */
- u64 vco = DIV_ROUND_CLOSEST_ULL(rate_in * f, r);
-
- if (vco > 1750000000 || vco < 340000000)
- out_of_spec = true;
- }
-
- if (out_of_spec) {
- if (!swapped) {
- u64 tmp = r;
-
- r = od;
- od = tmp;
- swapped = true;
- continue;
- } else {
- /*
- * Try looking ahead to see if there are
- * additional factors for the same
- * product.
- */
- if (i + 1 < ARRAY_SIZE(factors)) {
- u64 new_r, new_od;
-
- i++;
- new_r = UNPACK_R(factors[i]);
- new_od = UNPACK_OD(factors[i]);
- if (r * od == new_r * new_od) {
- r = new_r;
- od = new_od;
- swapped = false;
- continue;
- }
- i--;
- }
- break;
- }
- }
-
- error = DIV_ROUND_CLOSEST_ULL(f * inv_ratio, r * od);
- /* The lower 16 bits are spurious */
- error = abs((error - BIT(32))) >> 16;
-
- if (error < best_error) {
- best->r = r;
- best->f = f;
- best->od = od;
- best_error = error;
- }
- break;
- }
- } while (f < 64 && i + 1 < ARRAY_SIZE(factors) && error != 0);
-
- if (best_error == S64_MAX)
- return -EINVAL;
-
- log_debug("best error %lld\n", best_error);
- return 0;
-}
-
-static ulong k210_pll_set_rate(struct k210_clk_priv *priv, int id, ulong rate,
- ulong rate_in)
-{
- int err;
- const struct k210_pll_params *pll = &k210_plls[id];
- struct k210_pll_config config = {};
- u32 reg;
-
- if (rate_in < 0)
- return rate_in;
-
- log_debug("Calculating parameters with rate=%lu and rate_in=%lld\n",
- rate, rate_in);
- err = k210_pll_calc_config(rate, rate_in, &config);
- if (err)
- return err;
- log_debug("Got r=%u f=%u od=%u\n", config.r, config.f, config.od);
-
- /*
- * Don't use clk_disable as it might not actually disable the pll due to
- * refcounting
- */
- k210_pll_disable(clk);
-
- reg = readl(priv->base + pll->off);
- reg &= ~K210_PLL_CLKR
- & ~K210_PLL_CLKF
- & ~K210_PLL_CLKOD
- & ~K210_PLL_BWADJ;
- reg |= FIELD_PREP(K210_PLL_CLKR, config.r - 1)
- | FIELD_PREP(K210_PLL_CLKF, config.f - 1)
- | FIELD_PREP(K210_PLL_CLKOD, config.od - 1)
- | FIELD_PREP(K210_PLL_BWADJ, config.f - 1);
- writel(reg, priv->base + pll->off);
-
- err = k210_pll_enable(clk);
- if (err)
- return err;
-
- serial_setbrg();
- return clk_get_rate(clk);
-}
-#else
-ulong k210_pll_set_rate(struct k210_clk_priv *priv, int id, ulong rate,
- ulong rate_in)
-{
- return -ENOSYS;
-}
-#endif /* CONFIG_CLK_K210_SET_RATE */
-
-ulong k210_pll_get_rate(struct k210_clk_priv *priv, int id, ulong rate_in)
-{
- u64 r, f, od;
- u32 reg = readl(priv->base + k210_plls[id].off);
-
- if (rate_in < 0 || (reg & K210_PLL_BYPASS))
- return rate_in;
-
- if (!(reg & K210_PLL_PWRD))
- return 0;
-
- r = FIELD_GET(K210_PLL_CLKR, reg) + 1;
- f = FIELD_GET(K210_PLL_CLKF, reg) + 1;
- od = FIELD_GET(K210_PLL_CLKOD, reg) + 1;
-
- return DIV_ROUND_DOWN_ULL(((u64)rate_in) * f, r * od);
-}
-
-/*
- * Wait for the PLL to be locked. If the PLL is not locked, try clearing the
- * slip before retrying
- */
-void k210_pll_waitfor_lock(struct k210_clk_priv *priv, int id)
-{
- const struct k210_pll_params *pll = &k210_plls[id];
- u32 mask = GENMASK(pll->width - 1, 0) << pll->shift;
-
- while (true) {
- u32 reg = readl(priv->base + K210_SYSCTL_PLL_LOCK);
-
- if ((reg & mask) == mask)
- break;
-
- reg |= BIT(pll->shift + K210_PLL_CLEAR_SLIP);
- writel(reg, priv->base + K210_SYSCTL_PLL_LOCK);
- }
-}
-
-/* Adapted from sysctl_pll_enable */
-int k210_pll_enable(struct k210_clk_priv *priv, int id)
-{
- const struct k210_pll_params *pll = &k210_plls[id];
- u32 reg = readl(priv->base + pll->off);
-
- if ((reg & K210_PLL_PWRD) && (reg & K210_PLL_EN) &&
- !(reg & K210_PLL_RESET))
- return 0;
-
- reg |= K210_PLL_PWRD;
- writel(reg, priv->base + pll->off);
-
- /* Ensure reset is low before asserting it */
- reg &= ~K210_PLL_RESET;
- writel(reg, priv->base + pll->off);
- reg |= K210_PLL_RESET;
- writel(reg, priv->base + pll->off);
- nop();
- nop();
- reg &= ~K210_PLL_RESET;
- writel(reg, priv->base + pll->off);
-
- k210_pll_waitfor_lock(priv, id);
-
- reg &= ~K210_PLL_BYPASS;
- reg |= K210_PLL_EN;
- writel(reg, priv->base + pll->off);
-
- return 0;
-}
-
-int k210_pll_disable(struct k210_clk_priv *priv, int id)
-{
- const struct k210_pll_params *pll = &k210_plls[id];
- u32 reg = readl(priv->base + pll->off);
-
- /*
- * Bypassing before powering off is important so child clocks don't stop
- * working. This is especially important for pll0, the indirect parent
- * of the cpu clock.
- */
- reg |= K210_PLL_BYPASS;
- writel(reg, priv->base + pll->off);
-
- reg &= ~K210_PLL_PWRD;
- reg &= ~K210_PLL_EN;
- writel(reg, priv->base + pll->off);
- return 0;
-}