This pll code is primarily based on the code from the kendryte standalone sdk in
lib/drivers/sysctl.c. k210_pll_calc_params is roughly analogous to the algorithm
used to set the pll frequency, but it has been completely rewritten to be
fixed-point based.
Signed-off-by: Sean Anderson <sean...@gmail.com>
---
arch/riscv/mach-k210/Makefile | 1 -
board/sipeed/maix/Kconfig | 1 +
configs/sipeed_maix_bitm_config | 1 +
drivers/clk/Kconfig | 1 +
drivers/clk/Makefile | 1 +
drivers/clk/kendryte/Kconfig | 7 +
drivers/clk/kendryte/Makefile | 1 +
drivers/clk/kendryte/pll.c | 455 ++++++++++++++++++++++++++++++++
drivers/clk/kendryte/pll.h | 38 +++
9 files changed, 505 insertions(+), 1 deletion(-)
delete mode 100644 arch/riscv/mach-k210/Makefile
create mode 100644 drivers/clk/kendryte/Kconfig
create mode 100644 drivers/clk/kendryte/Makefile
create mode 100644 drivers/clk/kendryte/pll.c
create mode 100644 drivers/clk/kendryte/pll.h
diff --git a/arch/riscv/mach-k210/Makefile b/arch/riscv/mach-k210/Makefile
deleted file mode 100644
index 6defe5ccb2..0000000000
--- a/arch/riscv/mach-k210/Makefile
+++ /dev/null
@@ -1 +0,0 @@
-obj-y := sysctl.o
diff --git a/board/sipeed/maix/Kconfig b/board/sipeed/maix/Kconfig
index 257135b2cb..838f2fb263 100644
--- a/board/sipeed/maix/Kconfig
+++ b/board/sipeed/maix/Kconfig
@@ -37,6 +37,7 @@ config BOARD_SPECIFIC_OPTIONS
select ARCH_K210
imply SIFIVE_CLINT
imply K210_SYSCTL
+ imply CLK_K210
imply SPI
imply DM_GPIO
imply CMD_GPIO
diff --git a/configs/sipeed_maix_bitm_config b/configs/sipeed_maix_bitm_config
index bb2d2e7932..f20145feac 100644
--- a/configs/sipeed_maix_bitm_config
+++ b/configs/sipeed_maix_bitm_config
@@ -95,6 +95,7 @@ CONFIG_BLOCK_CACHE=y
CONFIG_CLK=y
CONFIG_CLK_CCF=y
CONFIG_CLK_COMPOSITE_CCF=y
+CONFIG_CLK_K210=y
CONFIG_CPU=y
CONFIG_CPU_RISCV=y
CONFIG_MMC=y
diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index 16d4237f89..af75c7c4cf 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -145,6 +145,7 @@ source "drivers/clk/analogbits/Kconfig"
source "drivers/clk/at91/Kconfig"
source "drivers/clk/exynos/Kconfig"
source "drivers/clk/imx/Kconfig"
+source "drivers/clk/kendryte/Kconfig"
source "drivers/clk/meson/Kconfig"
source "drivers/clk/mvebu/Kconfig"
source "drivers/clk/owl/Kconfig"
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index 06131edb9f..4f3893f6fc 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_CLK_BCM6345) += clk_bcm6345.o
obj-$(CONFIG_CLK_BOSTON) += clk_boston.o
obj-$(CONFIG_CLK_EXYNOS) += exynos/
obj-$(CONFIG_CLK_HSDK) += clk-hsdk-cgu.o
+obj-$(CONFIG_CLK_K210) += kendryte/
obj-$(CONFIG_CLK_MPC83XX) += mpc83xx_clk.o
obj-$(CONFIG_CLK_OWL) += owl/
obj-$(CONFIG_CLK_RENESAS) += renesas/
diff --git a/drivers/clk/kendryte/Kconfig b/drivers/clk/kendryte/Kconfig
new file mode 100644
index 0000000000..a178d50f5e
--- /dev/null
+++ b/drivers/clk/kendryte/Kconfig
@@ -0,0 +1,7 @@
+config CLK_K210
+ bool "Clock support for Kendryte K210"
+ depends on K210_SYSCTL
+ select CLK
+ select CLK_CCF
+ help
+ This enables support clock driver for Kendryte K210 platforms.
diff --git a/drivers/clk/kendryte/Makefile b/drivers/clk/kendryte/Makefile
new file mode 100644
index 0000000000..c56d93ea1c
--- /dev/null
+++ b/drivers/clk/kendryte/Makefile
@@ -0,0 +1 @@
+obj-y += pll.o
diff --git a/drivers/clk/kendryte/pll.c b/drivers/clk/kendryte/pll.c
new file mode 100644
index 0000000000..b6aa16cd0d
--- /dev/null
+++ b/drivers/clk/kendryte/pll.c
@@ -0,0 +1,455 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019 Sean Anderson <sean...@gmail.com>
+ */
+#include "pll.h"
+
+#define LOG_CATEGORY UCLASS_CLK
+#include <asm/io.h>
+/* For DIV_ROUND_DOWN_ULL, defined in linux/kernel.h */
+#include <div64.h>
+#include <dt-bindings/clock/k210-sysctl.h>
+#include <linux/bitfield.h>
+#include <linux/clk-provider.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <log.h>
+
+#define CLK_K210_PLL "clk_k210_pll"
+#define to_k210_pll(_clk) container_of(_clk, struct k210_pll, clk)
+
+static int k210_pll_enable(struct clk *clk);
+static int k210_pll_disable(struct clk *clk);
+
+/*
+ * The k210 PLLs have three factors: r, f, and od. 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 possible settings for the PLL. However, most of these settings can
+ * be ruled out immediately because they do not have the correct ratio. Of
these
+ * remaining options, there are at most 97, due to the limited range of f, r,
+ * and od.
+ *
+ * Throughout the calculation function, fixed point arithmetic is used. Because
+ * the range of rate and rate_in may be up to 1.8 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.
+ *
+ * The r and od factors are stored in a table. This is to make it easy to find
+ * the next-largest product.
+ *
+ * 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:
+ * factors = {}
+ * for i in range(1, 17):
+ * for j in range(1, 17):
+ * (x, y) = factors.get(i*j) or (17, 1)
+ * # Pick "balanced" factors
+ * if abs(i - j) < abs(x - y):
+ * factors[i*j] = (i, j)
+ * for k, v in sorted(factors.items()):
+ * 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(2, 2),
+ PACK(1, 5),
+ PACK(2, 3),
+ PACK(1, 7),
+ PACK(2, 4),
+ PACK(3, 3),
+ PACK(2, 5),
+ PACK(1, 11),
+ PACK(3, 4),
+ PACK(1, 13),
+ PACK(2, 7),
+ PACK(3, 5),
+ PACK(4, 4),
+ PACK(3, 6),
+ PACK(4, 5),
+ PACK(3, 7),
+ PACK(2, 11),
+ PACK(4, 6),
+ PACK(5, 5),
+ PACK(2, 13),
+ PACK(3, 9),
+ PACK(4, 7),
+ PACK(5, 6),
+ PACK(4, 8),
+ PACK(3, 11),
+ PACK(5, 7),
+ PACK(6, 6),
+ PACK(3, 13),
+ PACK(5, 8),
+ PACK(6, 7),
+ PACK(4, 11),
+ PACK(5, 9),
+ PACK(6, 8),
+ PACK(7, 7),
+ PACK(5, 10),
+ PACK(4, 13),
+ PACK(6, 9),
+ PACK(5, 11),
+ PACK(7, 8),
+ PACK(6, 10),
+ PACK(7, 9),
+ PACK(8, 8),
+ PACK(5, 13),
+ PACK(6, 11),
+ PACK(7, 10),
+ PACK(8, 9),
+ PACK(5, 15),
+ PACK(7, 11),
+ PACK(6, 13),
+ PACK(8, 10),
+ PACK(9, 9),
+ PACK(7, 12),
+ PACK(8, 11),
+ PACK(9, 10),
+ PACK(7, 13),
+ PACK(8, 12),
+ PACK(7, 14),
+ PACK(9, 11),
+ PACK(10, 10),
+ PACK(8, 13),
+ PACK(7, 15),
+ PACK(9, 12),
+ PACK(10, 11),
+ PACK(8, 14),
+ PACK(9, 13),
+ PACK(10, 12),
+ 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(12, 12),
+ 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),
+};
+
+struct k210_pll_params {
+ u8 r;
+ u8 f;
+ u8 od;
+};
+
+static int k210_pll_calc_params(u32 rate, u32 rate_in,
+ struct k210_pll_params *best)
+{
+ int i;
+ s64 error, best_error;
+ u64 ratio, inv_ratio; /* fixed point 32.32 ratio of the rates */
+ u64 r, f, od;
+
+ /* Can't go over 1.8 GHz */
+ if (rate > 1800000000)
+ 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;
+
+ /* Variables get immediately incremented, so start at -1th iteration */
+ i = -1;
+ f = 0;
+ r = 0;
+ od = 0;
+ best_error = S64_MAX;
+ /* do-while here so we always try at least one ratio */
+ do {
+ /*
+ * Try the next largest value for f (or r and od) and
+ * recalculate the other parameters based on that
+ */
+ if (rate > rate_in) {
+ i++;
+ r = UNPACK_R(factors[i]);
+ od = UNPACK_OD(factors[i]);
+
+ /* Round close */
+ f = (r * od * ratio + BIT(31)) >> 32;
+ if (f > 64)
+ f = 64;
+
+ } else {
+ u64 last_od = od;
+ u64 last_r = r;
+ 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;
+ }
+ }
+ /* 32.0 * 32.32 = 64.32 */
+ 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;
+ }
+ } while (f < 64 && i + 1 < ARRAY_SIZE(factors) && error != 0);
+
+ log_debug("best error %lld\n", best_error);
+ return 0;
+}
+
+static ulong k210_pll_set_rate(struct clk *clk, ulong rate)
+{
+ int err;
+ long long rate_in = clk_get_parent_rate(clk);
+ struct k210_pll_params params = {};
+ struct k210_pll *pll = to_k210_pll(clk);
+ 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_params(rate, rate_in, ¶ms);
+ if (err)
+ return err;
+ log_debug("Got r=%u f=%u od=%u\n", params.r, params.f, params.od);
+
+ /*
+ * Don't use clk_disable as it might not actually disable the pll due to
+ * refcounting
+ */
+ err = k210_pll_disable(clk);
+ if (err)
+ return err;
+
+ reg = readl(pll->reg);
+ reg &= ~K210_PLL_CLKR
+ & ~K210_PLL_CLKF
+ & ~K210_PLL_CLKOD
+ & ~K210_PLL_BWADJ;
+ reg |= FIELD_PREP(K210_PLL_CLKR, params.r - 1)
+ | FIELD_PREP(K210_PLL_CLKF, params.f - 1)
+ | FIELD_PREP(K210_PLL_CLKOD, params.od - 1)
+ | FIELD_PREP(K210_PLL_BWADJ, params.f - 1);
+ writel(reg, pll->reg);
+
+ err = k210_pll_enable(clk);
+ if (err)
+ return err;
+
+ return clk_get_rate(clk);
+}
+
+static ulong k210_pll_get_rate(struct clk *clk)
+{
+
+ long long rate_in = clk_get_parent_rate(clk);
+ struct k210_pll *pll = to_k210_pll(clk);
+ u64 r, f, od;
+ u32 reg = readl(pll->reg);
+
+ if (rate_in < 0)
+ return rate_in;
+
+ if (reg & K210_PLL_BYPASS)
+ return rate_in;
+
+ 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);
+}
+
+/* Check if the PLL is locked */
+static int k210_pll_locked(struct k210_pll *pll)
+{
+ u32 reg = readl(pll->lock);
+
+ return (reg & pll->lock_mask) == pll->lock_mask;
+}
+
+/*
+ * 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_pll *pll)
+{
+ while (!k210_pll_locked(pll)) {
+ u32 reg = readl(pll->lock);
+
+ reg |= BIT(pll->shift + K210_PLL_CLEAR_SLIP);
+ writel(reg, pll->lock);
+ udelay(1);
+ }
+}
+
+/* Adapted from sysctl_pll_enable */
+static int k210_pll_enable(struct clk *clk)
+{
+ struct k210_pll *pll = to_k210_pll(clk);
+ u32 reg = readl(pll->reg);
+
+ reg &= ~K210_PLL_BYPASS;
+ writel(reg, pll->reg);
+
+ reg |= K210_PLL_PWRD;
+ writel(reg, pll->reg);
+
+ /* Ensure reset is low before asserting it */
+ reg &= ~K210_PLL_RESET;
+ writel(reg, pll->reg);
+ reg |= K210_PLL_RESET;
+ writel(reg, pll->reg);
+ /* FIXME: this doesn't really have to be a whole microsecond */
+ udelay(1);
+ reg &= ~K210_PLL_RESET;
+ writel(reg, pll->reg);
+
+ k210_pll_waitfor_lock(pll);
+ return 0;
+}
+
+static int k210_pll_disable(struct clk *clk)
+{
+ struct k210_pll *pll = to_k210_pll(clk);
+ u32 reg = readl(pll->reg);
+
+ /*
+ * 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, pll->reg);
+
+ reg &= ~K210_PLL_PWRD;
+ writel(reg, pll->reg);
+ return 0;
+}
+
+const struct clk_ops k210_pll_ops = {
+ .get_rate = k210_pll_get_rate,
+ .set_rate = k210_pll_set_rate,
+ .enable = k210_pll_enable,
+ .disable = k210_pll_disable,
+};
+
+struct k210_pll *k210_clk_comp_pll(void __iomem *reg, void __iomem *lock,
+ u8 shift, u8 width)
+{
+ struct k210_pll *pll;
+
+
+ pll = kzalloc(sizeof(*pll), GFP_KERNEL);
+ if (!pll)
+ return pll;
+ pll->reg = reg;
+ pll->lock = lock;
+ pll->shift = shift;
+ pll->lock_mask = GENMASK(shift + width, shift);
+ return pll;
+}
+
+struct clk *k210_clk_pll(const char *name, const char *parent_name,
+ void __iomem *reg, void __iomem *lock, u8 shift,
+ u8 width)
+{
+ int err;
+ struct k210_pll *pll;
+
+ pll = k210_clk_comp_pll(reg, lock, shift, width);
+ if (!pll)
+ return ERR_PTR(-ENOMEM);
+
+ err = clk_register(&pll->clk, CLK_K210_PLL, name, parent_name);
+ if (err) {
+ kfree(pll);
+ return ERR_PTR(err);
+ }
+ return &pll->clk;
+}
+
+U_BOOT_DRIVER(k210_pll) = {
+ .name = CLK_K210_PLL,
+ .id = UCLASS_CLK,
+ .ops = &k210_pll_ops,
+ .flags = DM_FLAG_PRE_RELOC,
+};
diff --git a/drivers/clk/kendryte/pll.h b/drivers/clk/kendryte/pll.h
new file mode 100644
index 0000000000..6a8734a295
--- /dev/null
+++ b/drivers/clk/kendryte/pll.h
@@ -0,0 +1,38 @@
+#ifndef K210_PLL_H
+#define K210_PLL_H
+
+#include <clk.h>
+
+#define K210_PLL_CLKR GENMASK(3, 0)
+#define K210_PLL_CLKF GENMASK(9, 4)
+#define K210_PLL_CLKOD GENMASK(13, 10)
+#define K210_PLL_BWADJ GENMASK(19, 14)
+#define K210_PLL_RESET BIT(20)
+#define K210_PLL_PWRD BIT(21)
+#define K210_PLL_INTFB BIT(22)
+#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
+
+struct k210_pll {
+ struct clk clk;
+ void __iomem *reg; /* Base PLL register */
+ void __iomem *lock; /* Common PLL lock register */
+ u8 shift; /* Offset of bits in lock register */
+ u8 lock_mask; /* Mask of lock bits to test against, pre-shifted */
+};
+
+extern const struct clk_ops k210_pll_ops;
+
+struct k210_pll *k210_clk_comp_pll(void __iomem *reg, void __iomem *lock,
+ u8 shift, u8 width);
+struct clk *k210_clk_pll(const char *name, const char *parent_name,
+ void __iomem *reg, void __iomem *lock, u8 shift,
+ u8 width);
+
+#endif /* K210_PLL_H */
--
2.24.1
