1 files changed, 370 insertions, 0 deletions
diff --git a/drivers/clk/ti/clkt_dpll.c b/drivers/clk/ti/clkt_dpll.c
new file mode 100644
index 000000000..87ece6cd4
--- /dev/null
+++ b/drivers/clk/ti/clkt_dpll.c
@@ -0,0 +1,370 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * OMAP2/3/4 DPLL clock functions
+ *
+ * Copyright (C) 2005-2008 Texas Instruments, Inc.
+ * Copyright (C) 2004-2010 Nokia Corporation
+ *
+ * Contacts:
+ * Richard Woodruff <r-woodruff2@ti.com>
+ * Paul Walmsley
+ */
+#undef DEBUG
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/io.h>
+#include <linux/clk/ti.h>
+
+#include <asm/div64.h>
+
+#include "clock.h"
+
+/* DPLL rate rounding: minimum DPLL multiplier, divider values */
+#define DPLL_MIN_MULTIPLIER		2
+#define DPLL_MIN_DIVIDER		1
+
+/* Possible error results from _dpll_test_mult */
+#define DPLL_MULT_UNDERFLOW		-1
+
+/*
+ * Scale factor to mitigate roundoff errors in DPLL rate rounding.
+ * The higher the scale factor, the greater the risk of arithmetic overflow,
+ * but the closer the rounded rate to the target rate.  DPLL_SCALE_FACTOR
+ * must be a power of DPLL_SCALE_BASE.
+ */
+#define DPLL_SCALE_FACTOR		64
+#define DPLL_SCALE_BASE			2
+#define DPLL_ROUNDING_VAL		((DPLL_SCALE_BASE / 2) * \
+					 (DPLL_SCALE_FACTOR / DPLL_SCALE_BASE))
+
+/*
+ * DPLL valid Fint frequency range for OMAP36xx and OMAP4xxx.
+ * From device data manual section 4.3 "DPLL and DLL Specifications".
+ */
+#define OMAP3PLUS_DPLL_FINT_JTYPE_MIN	500000
+#define OMAP3PLUS_DPLL_FINT_JTYPE_MAX	2500000
+
+/* _dpll_test_fint() return codes */
+#define DPLL_FINT_UNDERFLOW		-1
+#define DPLL_FINT_INVALID		-2
+
+/* Private functions */
+
+/*
+ * _dpll_test_fint - test whether an Fint value is valid for the DPLL
+ * @clk: DPLL struct clk to test
+ * @n: divider value (N) to test
+ *
+ * Tests whether a particular divider @n will result in a valid DPLL
+ * internal clock frequency Fint. See the 34xx TRM 4.7.6.2 "DPLL Jitter
+ * Correction".  Returns 0 if OK, -1 if the enclosing loop can terminate
+ * (assuming that it is counting N upwards), or -2 if the enclosing loop
+ * should skip to the next iteration (again assuming N is increasing).
+ */
+static int _dpll_test_fint(struct clk_hw_omap *clk, unsigned int n)
+{
+	struct dpll_data *dd;
+	long fint, fint_min, fint_max;
+	int ret = 0;
+
+	dd = clk->dpll_data;
+
+	/* DPLL divider must result in a valid jitter correction val */
+	fint = clk_hw_get_rate(clk_hw_get_parent(&clk->hw)) / n;
+
+	if (dd->flags & DPLL_J_TYPE) {
+		fint_min = OMAP3PLUS_DPLL_FINT_JTYPE_MIN;
+		fint_max = OMAP3PLUS_DPLL_FINT_JTYPE_MAX;
+	} else {
+		fint_min = ti_clk_get_features()->fint_min;
+		fint_max = ti_clk_get_features()->fint_max;
+	}
+
+	if (!fint_min || !fint_max) {
+		WARN(1, "No fint limits available!\n");
+		return DPLL_FINT_INVALID;
+	}
+
+	if (fint < ti_clk_get_features()->fint_min) {
+		pr_debug("rejecting n=%d due to Fint failure, lowering max_divider\n",
+			 n);
+		dd->max_divider = n;
+		ret = DPLL_FINT_UNDERFLOW;
+	} else if (fint > ti_clk_get_features()->fint_max) {
+		pr_debug("rejecting n=%d due to Fint failure, boosting min_divider\n",
+			 n);
+		dd->min_divider = n;
+		ret = DPLL_FINT_INVALID;
+	} else if (fint > ti_clk_get_features()->fint_band1_max &&
+		   fint < ti_clk_get_features()->fint_band2_min) {
+		pr_debug("rejecting n=%d due to Fint failure\n", n);
+		ret = DPLL_FINT_INVALID;
+	}
+
+	return ret;
+}
+
+static unsigned long _dpll_compute_new_rate(unsigned long parent_rate,
+					    unsigned int m, unsigned int n)
+{
+	unsigned long long num;
+
+	num = (unsigned long long)parent_rate * m;
+	do_div(num, n);
+	return num;
+}
+
+/*
+ * _dpll_test_mult - test a DPLL multiplier value
+ * @m: pointer to the DPLL m (multiplier) value under test
+ * @n: current DPLL n (divider) value under test
+ * @new_rate: pointer to storage for the resulting rounded rate
+ * @target_rate: the desired DPLL rate
+ * @parent_rate: the DPLL's parent clock rate
+ *
+ * This code tests a DPLL multiplier value, ensuring that the
+ * resulting rate will not be higher than the target_rate, and that
+ * the multiplier value itself is valid for the DPLL.  Initially, the
+ * integer pointed to by the m argument should be prescaled by
+ * multiplying by DPLL_SCALE_FACTOR.  The code will replace this with
+ * a non-scaled m upon return.  This non-scaled m will result in a
+ * new_rate as close as possible to target_rate (but not greater than
+ * target_rate) given the current (parent_rate, n, prescaled m)
+ * triple. Returns DPLL_MULT_UNDERFLOW in the event that the
+ * non-scaled m attempted to underflow, which can allow the calling
+ * function to bail out early; or 0 upon success.
+ */
+static int _dpll_test_mult(int *m, int n, unsigned long *new_rate,
+			   unsigned long target_rate,
+			   unsigned long parent_rate)
+{
+	int r = 0, carry = 0;
+
+	/* Unscale m and round if necessary */
+	if (*m % DPLL_SCALE_FACTOR >= DPLL_ROUNDING_VAL)
+		carry = 1;
+	*m = (*m / DPLL_SCALE_FACTOR) + carry;
+
+	/*
+	 * The new rate must be <= the target rate to avoid programming
+	 * a rate that is impossible for the hardware to handle
+	 */
+	*new_rate = _dpll_compute_new_rate(parent_rate, *m, n);
+	if (*new_rate > target_rate) {
+		(*m)--;
+		*new_rate = 0;
+	}
+
+	/* Guard against m underflow */
+	if (*m < DPLL_MIN_MULTIPLIER) {
+		*m = DPLL_MIN_MULTIPLIER;
+		*new_rate = 0;
+		r = DPLL_MULT_UNDERFLOW;
+	}
+
+	if (*new_rate == 0)
+		*new_rate = _dpll_compute_new_rate(parent_rate, *m, n);
+
+	return r;
+}
+
+/**
+ * _omap2_dpll_is_in_bypass - check if DPLL is in bypass mode or not
+ * @v: bitfield value of the DPLL enable
+ *
+ * Checks given DPLL enable bitfield to see whether the DPLL is in bypass
+ * mode or not. Returns 1 if the DPLL is in bypass, 0 otherwise.
+ */
+static int _omap2_dpll_is_in_bypass(u32 v)
+{
+	u8 mask, val;
+
+	mask = ti_clk_get_features()->dpll_bypass_vals;
+
+	/*
+	 * Each set bit in the mask corresponds to a bypass value equal
+	 * to the bitshift. Go through each set-bit in the mask and
+	 * compare against the given register value.
+	 */
+	while (mask) {
+		val = __ffs(mask);
+		mask ^= (1 << val);
+		if (v == val)
+			return 1;
+	}
+
+	return 0;
+}
+
+/* Public functions */
+u8 omap2_init_dpll_parent(struct clk_hw *hw)
+{
+	struct clk_hw_omap *clk = to_clk_hw_omap(hw);
+	u32 v;
+	struct dpll_data *dd;
+
+	dd = clk->dpll_data;
+	if (!dd)
+		return -EINVAL;
+
+	v = ti_clk_ll_ops->clk_readl(&dd->control_reg);
+	v &= dd->enable_mask;
+	v >>= __ffs(dd->enable_mask);
+
+	/* Reparent the struct clk in case the dpll is in bypass */
+	if (_omap2_dpll_is_in_bypass(v))
+		return 1;
+
+	return 0;
+}
+
+/**
+ * omap2_get_dpll_rate - returns the current DPLL CLKOUT rate
+ * @clk: struct clk * of a DPLL
+ *
+ * DPLLs can be locked or bypassed - basically, enabled or disabled.
+ * When locked, the DPLL output depends on the M and N values.  When
+ * bypassed, on OMAP2xxx, the output rate is either the 32KiHz clock
+ * or sys_clk.  Bypass rates on OMAP3 depend on the DPLL: DPLLs 1 and
+ * 2 are bypassed with dpll1_fclk and dpll2_fclk respectively
+ * (generated by DPLL3), while DPLL 3, 4, and 5 bypass rates are sys_clk.
+ * Returns the current DPLL CLKOUT rate (*not* CLKOUTX2) if the DPLL is
+ * locked, or the appropriate bypass rate if the DPLL is bypassed, or 0
+ * if the clock @clk is not a DPLL.
+ */
+unsigned long omap2_get_dpll_rate(struct clk_hw_omap *clk)
+{
+	u64 dpll_clk;
+	u32 dpll_mult, dpll_div, v;
+	struct dpll_data *dd;
+
+	dd = clk->dpll_data;
+	if (!dd)
+		return 0;
+
+	/* Return bypass rate if DPLL is bypassed */
+	v = ti_clk_ll_ops->clk_readl(&dd->control_reg);
+	v &= dd->enable_mask;
+	v >>= __ffs(dd->enable_mask);
+
+	if (_omap2_dpll_is_in_bypass(v))
+		return clk_hw_get_rate(dd->clk_bypass);
+
+	v = ti_clk_ll_ops->clk_readl(&dd->mult_div1_reg);
+	dpll_mult = v & dd->mult_mask;
+	dpll_mult >>= __ffs(dd->mult_mask);
+	dpll_div = v & dd->div1_mask;
+	dpll_div >>= __ffs(dd->div1_mask);
+
+	dpll_clk = (u64)clk_hw_get_rate(dd->clk_ref) * dpll_mult;
+	do_div(dpll_clk, dpll_div + 1);
+
+	return dpll_clk;
+}
+
+/* DPLL rate rounding code */
+
+/**
+ * omap2_dpll_round_rate - round a target rate for an OMAP DPLL
+ * @clk: struct clk * for a DPLL
+ * @target_rate: desired DPLL clock rate
+ *
+ * Given a DPLL and a desired target rate, round the target rate to a
+ * possible, programmable rate for this DPLL.  Attempts to select the
+ * minimum possible n.  Stores the computed (m, n) in the DPLL's
+ * dpll_data structure so set_rate() will not need to call this
+ * (expensive) function again.  Returns ~0 if the target rate cannot
+ * be rounded, or the rounded rate upon success.
+ */
+long omap2_dpll_round_rate(struct clk_hw *hw, unsigned long target_rate,
+			   unsigned long *parent_rate)
+{
+	struct clk_hw_omap *clk = to_clk_hw_omap(hw);
+	int m, n, r, scaled_max_m;
+	int min_delta_m = INT_MAX, min_delta_n = INT_MAX;
+	unsigned long scaled_rt_rp;
+	unsigned long new_rate = 0;
+	struct dpll_data *dd;
+	unsigned long ref_rate;
+	long delta;
+	long prev_min_delta = LONG_MAX;
+	const char *clk_name;
+
+	if (!clk || !clk->dpll_data)
+		return ~0;
+
+	dd = clk->dpll_data;
+
+	if (dd->max_rate && target_rate > dd->max_rate)
+		target_rate = dd->max_rate;
+
+	ref_rate = clk_hw_get_rate(dd->clk_ref);
+	clk_name = clk_hw_get_name(hw);
+	pr_debug("clock: %s: starting DPLL round_rate, target rate %lu\n",
+		 clk_name, target_rate);
+
+	scaled_rt_rp = target_rate / (ref_rate / DPLL_SCALE_FACTOR);
+	scaled_max_m = dd->max_multiplier * DPLL_SCALE_FACTOR;
+
+	dd->last_rounded_rate = 0;
+
+	for (n = dd->min_divider; n <= dd->max_divider; n++) {
+		/* Is the (input clk, divider) pair valid for the DPLL? */
+		r = _dpll_test_fint(clk, n);
+		if (r == DPLL_FINT_UNDERFLOW)
+			break;
+		else if (r == DPLL_FINT_INVALID)
+			continue;
+
+		/* Compute the scaled DPLL multiplier, based on the divider */
+		m = scaled_rt_rp * n;
+
+		/*
+		 * Since we're counting n up, a m overflow means we
+		 * can bail out completely (since as n increases in
+		 * the next iteration, there's no way that m can
+		 * increase beyond the current m)
+		 */
+		if (m > scaled_max_m)
+			break;
+
+		r = _dpll_test_mult(&m, n, &new_rate, target_rate,
+				    ref_rate);
+
+		/* m can't be set low enough for this n - try with a larger n */
+		if (r == DPLL_MULT_UNDERFLOW)
+			continue;
+
+		/* skip rates above our target rate */
+		delta = target_rate - new_rate;
+		if (delta < 0)
+			continue;
+
+		if (delta < prev_min_delta) {
+			prev_min_delta = delta;
+			min_delta_m = m;
+			min_delta_n = n;
+		}
+
+		pr_debug("clock: %s: m = %d: n = %d: new_rate = %lu\n",
+			 clk_name, m, n, new_rate);
+
+		if (delta == 0)
+			break;
+	}
+
+	if (prev_min_delta == LONG_MAX) {
+		pr_debug("clock: %s: cannot round to rate %lu\n",
+			 clk_name, target_rate);
+		return ~0;
+	}
+
+	dd->last_rounded_m = min_delta_m;
+	dd->last_rounded_n = min_delta_n;
+	dd->last_rounded_rate = target_rate - prev_min_delta;
+
+	return dd->last_rounded_rate;
+}