clk: sifive: Factor-out PLL library as separate module
To match SiFive clock driver with latest Linux, we factor-out PLL
library as separate module under drivers/clk/analogbits.
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/clk/analogbits/Kconfig b/drivers/clk/analogbits/Kconfig
new file mode 100644
index 0000000..1d25e6f
--- /dev/null
+++ b/drivers/clk/analogbits/Kconfig
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
+
+config CLK_ANALOGBITS_WRPLL_CLN28HPC
+ bool
diff --git a/drivers/clk/analogbits/Makefile b/drivers/clk/analogbits/Makefile
new file mode 100644
index 0000000..ec1bb40
--- /dev/null
+++ b/drivers/clk/analogbits/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0+
+
+obj-$(CONFIG_CLK_ANALOGBITS_WRPLL_CLN28HPC) += wrpll-cln28hpc.o
diff --git a/drivers/clk/analogbits/wrpll-cln28hpc.c b/drivers/clk/analogbits/wrpll-cln28hpc.c
new file mode 100644
index 0000000..68eb114
--- /dev/null
+++ b/drivers/clk/analogbits/wrpll-cln28hpc.c
@@ -0,0 +1,389 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Copyright (C) 2018 SiFive, Inc.
+ * Wesley Terpstra
+ * Paul Walmsley
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * This library supports configuration parsing and reprogramming of
+ * the CLN28HPC variant of the Analog Bits Wide Range PLL. The
+ * intention is for this library to be reusable for any device that
+ * integrates this PLL; thus the register structure and programming
+ * details are expected to be provided by a separate IP block driver.
+ *
+ * The bulk of this code is primarily useful for clock configurations
+ * that must operate at arbitrary rates, as opposed to clock configurations
+ * that are restricted by software or manufacturer guidance to a small,
+ * pre-determined set of performance points.
+ *
+ * References:
+ * - Analog Bits "Wide Range PLL Datasheet", version 2015.10.01
+ * - SiFive FU540-C000 Manual v1p0, Chapter 7 "Clocking and Reset"
+ */
+
+#include <linux/bug.h>
+#include <linux/err.h>
+#include <linux/log2.h>
+#include <linux/math64.h>
+#include <linux/clk/analogbits-wrpll-cln28hpc.h>
+
+/* MIN_INPUT_FREQ: minimum input clock frequency, in Hz (Fref_min) */
+#define MIN_INPUT_FREQ 7000000
+
+/* MAX_INPUT_FREQ: maximum input clock frequency, in Hz (Fref_max) */
+#define MAX_INPUT_FREQ 600000000
+
+/* MIN_POST_DIVIDE_REF_FREQ: minimum post-divider reference frequency, in Hz */
+#define MIN_POST_DIVR_FREQ 7000000
+
+/* MAX_POST_DIVIDE_REF_FREQ: maximum post-divider reference frequency, in Hz */
+#define MAX_POST_DIVR_FREQ 200000000
+
+/* MIN_VCO_FREQ: minimum VCO frequency, in Hz (Fvco_min) */
+#define MIN_VCO_FREQ 2400000000UL
+
+/* MAX_VCO_FREQ: maximum VCO frequency, in Hz (Fvco_max) */
+#define MAX_VCO_FREQ 4800000000ULL
+
+/* MAX_DIVQ_DIVISOR: maximum output divisor. Selected by DIVQ = 6 */
+#define MAX_DIVQ_DIVISOR 64
+
+/* MAX_DIVR_DIVISOR: maximum reference divisor. Selected by DIVR = 63 */
+#define MAX_DIVR_DIVISOR 64
+
+/* MAX_LOCK_US: maximum PLL lock time, in microseconds (tLOCK_max) */
+#define MAX_LOCK_US 70
+
+/*
+ * ROUND_SHIFT: number of bits to shift to avoid precision loss in the rounding
+ * algorithm
+ */
+#define ROUND_SHIFT 20
+
+/*
+ * Private functions
+ */
+
+/**
+ * __wrpll_calc_filter_range() - determine PLL loop filter bandwidth
+ * @post_divr_freq: input clock rate after the R divider
+ *
+ * Select the value to be presented to the PLL RANGE input signals, based
+ * on the input clock frequency after the post-R-divider @post_divr_freq.
+ * This code follows the recommendations in the PLL datasheet for filter
+ * range selection.
+ *
+ * Return: The RANGE value to be presented to the PLL configuration inputs,
+ * or -1 upon error.
+ */
+static int __wrpll_calc_filter_range(unsigned long post_divr_freq)
+{
+ u8 range;
+
+ if (post_divr_freq < MIN_POST_DIVR_FREQ ||
+ post_divr_freq > MAX_POST_DIVR_FREQ) {
+ WARN(1, "%s: post-divider reference freq out of range: %lu",
+ __func__, post_divr_freq);
+ return -1;
+ }
+
+ if (post_divr_freq < 11000000)
+ range = 1;
+ else if (post_divr_freq < 18000000)
+ range = 2;
+ else if (post_divr_freq < 30000000)
+ range = 3;
+ else if (post_divr_freq < 50000000)
+ range = 4;
+ else if (post_divr_freq < 80000000)
+ range = 5;
+ else if (post_divr_freq < 130000000)
+ range = 6;
+ else
+ range = 7;
+
+ return range;
+}
+
+/**
+ * __wrpll_calc_fbdiv() - return feedback fixed divide value
+ * @c: ptr to a struct analogbits_wrpll_cfg record to read from
+ *
+ * The internal feedback path includes a fixed by-two divider; the
+ * external feedback path does not. Return the appropriate divider
+ * value (2 or 1) depending on whether internal or external feedback
+ * is enabled. This code doesn't test for invalid configurations
+ * (e.g. both or neither of WRPLL_FLAGS_*_FEEDBACK are set); it relies
+ * on the caller to do so.
+ *
+ * Context: Any context. Caller must protect the memory pointed to by
+ * @c from simultaneous modification.
+ *
+ * Return: 2 if internal feedback is enabled or 1 if external feedback
+ * is enabled.
+ */
+static u8 __wrpll_calc_fbdiv(struct analogbits_wrpll_cfg *c)
+{
+ return (c->flags & WRPLL_FLAGS_INT_FEEDBACK_MASK) ? 2 : 1;
+}
+
+/**
+ * __wrpll_calc_divq() - determine DIVQ based on target PLL output clock rate
+ * @target_rate: target PLL output clock rate
+ * @vco_rate: pointer to a u64 to store the computed VCO rate into
+ *
+ * Determine a reasonable value for the PLL Q post-divider, based on the
+ * target output rate @target_rate for the PLL. Along with returning the
+ * computed Q divider value as the return value, this function stores the
+ * desired target VCO rate into the variable pointed to by @vco_rate.
+ *
+ * Context: Any context. Caller must protect the memory pointed to by
+ * @vco_rate from simultaneous access or modification.
+ *
+ * Return: a positive integer DIVQ value to be programmed into the hardware
+ * upon success, or 0 upon error (since 0 is an invalid DIVQ value)
+ */
+static u8 __wrpll_calc_divq(u32 target_rate, u64 *vco_rate)
+{
+ u64 s;
+ u8 divq = 0;
+
+ if (!vco_rate) {
+ WARN_ON(1);
+ goto wcd_out;
+ }
+
+ s = div_u64(MAX_VCO_FREQ, target_rate);
+ if (s <= 1) {
+ divq = 1;
+ *vco_rate = MAX_VCO_FREQ;
+ } else if (s > MAX_DIVQ_DIVISOR) {
+ divq = ilog2(MAX_DIVQ_DIVISOR);
+ *vco_rate = MIN_VCO_FREQ;
+ } else {
+ divq = ilog2(s);
+ *vco_rate = target_rate << divq;
+ }
+
+wcd_out:
+ return divq;
+}
+
+/**
+ * __wrpll_update_parent_rate() - update PLL data when parent rate changes
+ * @c: ptr to a struct analogbits_wrpll_cfg record to write PLL data to
+ * @parent_rate: PLL input refclk rate (pre-R-divider)
+ *
+ * Pre-compute some data used by the PLL configuration algorithm when
+ * the PLL's reference clock rate changes. The intention is to avoid
+ * computation when the parent rate remains constant - expected to be
+ * the common case.
+ *
+ * Returns: 0 upon success or -1 if the reference clock rate is out of range.
+ */
+static int __wrpll_update_parent_rate(struct analogbits_wrpll_cfg *c,
+ unsigned long parent_rate)
+{
+ u8 max_r_for_parent;
+
+ if (parent_rate > MAX_INPUT_FREQ || parent_rate < MIN_POST_DIVR_FREQ)
+ return -1;
+
+ c->_parent_rate = parent_rate;
+ max_r_for_parent = div_u64(parent_rate, MIN_POST_DIVR_FREQ);
+ c->_max_r = min_t(u8, MAX_DIVR_DIVISOR, max_r_for_parent);
+
+ /* Round up */
+ c->_init_r = div_u64(parent_rate + MAX_POST_DIVR_FREQ - 1,
+ MAX_POST_DIVR_FREQ);
+
+ return 0;
+}
+
+/*
+ * Public functions
+ */
+
+/**
+ * analogbits_wrpll_configure() - compute PLL configuration for a target rate
+ * @c: ptr to a struct analogbits_wrpll_cfg record to write into
+ * @target_rate: target PLL output clock rate (post-Q-divider)
+ * @parent_rate: PLL input refclk rate (pre-R-divider)
+ *
+ * Given a pointer to a PLL context @c, a desired PLL target output
+ * rate @target_rate, and a reference clock input rate @parent_rate,
+ * compute the appropriate PLL signal configuration values. PLL
+ * reprogramming is not glitchless, so the caller should switch any
+ * downstream logic to a different clock source or clock-gate it
+ * before presenting these values to the PLL configuration signals.
+ *
+ * The caller must pass this function a pre-initialized struct
+ * analogbits_wrpll_cfg record: either initialized to zero (with the
+ * exception of the .name and .flags fields) or read from the PLL.
+ *
+ * Context: Any context. Caller must protect the memory pointed to by @c
+ * from simultaneous access or modification.
+ *
+ * Return: 0 upon success; anything else upon failure.
+ */
+int analogbits_wrpll_configure_for_rate(struct analogbits_wrpll_cfg *c,
+ u32 target_rate,
+ unsigned long parent_rate)
+{
+ unsigned long ratio;
+ u64 target_vco_rate, delta, best_delta, f_pre_div, vco, vco_pre;
+ u32 best_f, f, post_divr_freq, fbcfg;
+ u8 fbdiv, divq, best_r, r;
+
+ if (!c)
+ return -1;
+
+ if (c->flags == 0) {
+ WARN(1, "%s called with uninitialized PLL config", __func__);
+ return -1;
+ }
+
+ fbcfg = WRPLL_FLAGS_INT_FEEDBACK_MASK | WRPLL_FLAGS_EXT_FEEDBACK_MASK;
+ if ((c->flags & fbcfg) == fbcfg) {
+ WARN(1, "%s called with invalid PLL config", __func__);
+ return -1;
+ }
+
+ if (c->flags == WRPLL_FLAGS_EXT_FEEDBACK_MASK) {
+ WARN(1, "%s: external feedback mode not currently supported",
+ __func__);
+ return -1;
+ }
+
+ /* Initialize rounding data if it hasn't been initialized already */
+ if (parent_rate != c->_parent_rate) {
+ if (__wrpll_update_parent_rate(c, parent_rate)) {
+ pr_err("%s: PLL input rate is out of range\n",
+ __func__);
+ return -1;
+ }
+ }
+
+ c->flags &= ~WRPLL_FLAGS_RESET_MASK;
+
+ /* Put the PLL into bypass if the user requests the parent clock rate */
+ if (target_rate == parent_rate) {
+ c->flags |= WRPLL_FLAGS_BYPASS_MASK;
+ return 0;
+ }
+ c->flags &= ~WRPLL_FLAGS_BYPASS_MASK;
+
+ /* Calculate the Q shift and target VCO rate */
+ divq = __wrpll_calc_divq(target_rate, &target_vco_rate);
+ if (divq == 0)
+ return -1;
+ c->divq = divq;
+
+ /* Precalculate the pre-Q divider target ratio */
+ ratio = div64_u64((target_vco_rate << ROUND_SHIFT), parent_rate);
+
+ fbdiv = __wrpll_calc_fbdiv(c);
+ best_r = 0;
+ best_f = 0;
+ best_delta = MAX_VCO_FREQ;
+
+ /*
+ * Consider all values for R which land within
+ * [MIN_POST_DIVR_FREQ, MAX_POST_DIVR_FREQ]; prefer smaller R
+ */
+ for (r = c->_init_r; r <= c->_max_r; ++r) {
+ /* What is the best F we can pick in this case? */
+ f_pre_div = ratio * r;
+ f = (f_pre_div + (1 << ROUND_SHIFT)) >> ROUND_SHIFT;
+ f >>= (fbdiv - 1);
+
+ post_divr_freq = div_u64(parent_rate, r);
+ vco_pre = fbdiv * post_divr_freq;
+ vco = vco_pre * f;
+
+ /* Ensure rounding didn't take us out of range */
+ if (vco > target_vco_rate) {
+ --f;
+ vco = vco_pre * f;
+ } else if (vco < MIN_VCO_FREQ) {
+ ++f;
+ vco = vco_pre * f;
+ }
+
+ delta = abs(target_rate - vco);
+ if (delta < best_delta) {
+ best_delta = delta;
+ best_r = r;
+ best_f = f;
+ }
+ }
+
+ c->divr = best_r - 1;
+ c->divf = best_f - 1;
+
+ post_divr_freq = div_u64(parent_rate, best_r);
+
+ /* Pick the best PLL jitter filter */
+ c->range = __wrpll_calc_filter_range(post_divr_freq);
+
+ return 0;
+}
+
+/**
+ * analogbits_wrpll_calc_output_rate() - calculate the PLL's target output rate
+ * @c: ptr to a struct analogbits_wrpll_cfg record to read from
+ * @parent_rate: PLL refclk rate
+ *
+ * Given a pointer to the PLL's current input configuration @c and the
+ * PLL's input reference clock rate @parent_rate (before the R
+ * pre-divider), calculate the PLL's output clock rate (after the Q
+ * post-divider)
+ *
+ * Context: Any context. Caller must protect the memory pointed to by @c
+ * from simultaneous modification.
+ *
+ * Return: the PLL's output clock rate, in Hz.
+ */
+unsigned long analogbits_wrpll_calc_output_rate(struct analogbits_wrpll_cfg *c,
+ unsigned long parent_rate)
+{
+ u8 fbdiv;
+ u64 n;
+
+ WARN(c->flags & WRPLL_FLAGS_EXT_FEEDBACK_MASK,
+ "external feedback mode not yet supported");
+
+ fbdiv = __wrpll_calc_fbdiv(c);
+ n = parent_rate * fbdiv * (c->divf + 1);
+ n = div_u64(n, (c->divr + 1));
+ n >>= c->divq;
+
+ return n;
+}
+
+/**
+ * analogbits_wrpll_calc_max_lock_us() - return the time for the PLL to lock
+ * @c: ptr to a struct analogbits_wrpll_cfg record to read from
+ *
+ * Return the minimum amount of time (in microseconds) that the caller
+ * must wait after reprogramming the PLL to ensure that it is locked
+ * to the input frequency and stable. This is likely to depend on the DIVR
+ * value; this is under discussion with the manufacturer.
+ *
+ * Return: the minimum amount of time the caller must wait for the PLL
+ * to lock (in microseconds)
+ */
+unsigned int analogbits_wrpll_calc_max_lock_us(struct analogbits_wrpll_cfg *c)
+{
+ return MAX_LOCK_US;
+}