1 files changed, 386 insertions, 0 deletions
diff --git a/arch/arm/mach-omap2/clkt_dpll.c b/arch/arm/mach-omap2/clkt_dpll.c
new file mode 100644
index 000000000000..6ce512e902c6
--- /dev/null
+++ b/arch/arm/mach-omap2/clkt_dpll.c
@@ -0,0 +1,386 @@
+/*
+ * 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
+ *
+ * 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.
+ */
+#undef DEBUG
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+
+#include <asm/div64.h>
+
+#include <plat/clock.h>
+
+#include "clock.h"
+#include "cm.h"
+#include "cm-regbits-24xx.h"
+#include "cm-regbits-34xx.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 band limits - from 34xx TRM Section 4.7.6.2 */
+#define DPLL_FINT_BAND1_MIN		750000
+#define DPLL_FINT_BAND1_MAX		2100000
+#define DPLL_FINT_BAND2_MIN		7500000
+#define DPLL_FINT_BAND2_MAX		21000000
+
+/* _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 *clk, u8 n)
+{
+	struct dpll_data *dd;
+	long fint;
+	int ret = 0;
+
+	dd = clk->dpll_data;
+
+	/* DPLL divider must result in a valid jitter correction val */
+	fint = clk->parent->rate / (n + 1);
+	if (fint < DPLL_FINT_BAND1_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 > DPLL_FINT_BAND1_MAX &&
+		   fint < DPLL_FINT_BAND2_MIN) {
+
+		pr_debug("rejecting n=%d due to Fint failure\n", n);
+		ret = DPLL_FINT_INVALID;
+
+	} else if (fint > DPLL_FINT_BAND2_MAX) {
+
+		pr_debug("rejecting n=%d due to Fint failure, "
+			 "boosting min_divider\n", n);
+		dd->min_divider = 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;
+}
+
+/* Public functions */
+
+void omap2_init_dpll_parent(struct clk *clk)
+{
+	u32 v;
+	struct dpll_data *dd;
+
+	dd = clk->dpll_data;
+	if (!dd)
+		return;
+
+	/* Return bypass rate if DPLL is bypassed */
+	v = __raw_readl(dd->control_reg);
+	v &= dd->enable_mask;
+	v >>= __ffs(dd->enable_mask);
+
+	/* Reparent in case the dpll is in bypass */
+	if (cpu_is_omap24xx()) {
+		if (v == OMAP2XXX_EN_DPLL_LPBYPASS ||
+		    v == OMAP2XXX_EN_DPLL_FRBYPASS)
+			clk_reparent(clk, dd->clk_bypass);
+	} else if (cpu_is_omap34xx()) {
+		if (v == OMAP3XXX_EN_DPLL_LPBYPASS ||
+		    v == OMAP3XXX_EN_DPLL_FRBYPASS)
+			clk_reparent(clk, dd->clk_bypass);
+	} else if (cpu_is_omap44xx()) {
+		if (v == OMAP4XXX_EN_DPLL_LPBYPASS ||
+		    v == OMAP4XXX_EN_DPLL_FRBYPASS ||
+		    v == OMAP4XXX_EN_DPLL_MNBYPASS)
+			clk_reparent(clk, dd->clk_bypass);
+	}
+	return;
+}
+
+/**
+ * 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.
+ */
+u32 omap2_get_dpll_rate(struct clk *clk)
+{
+	long long 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 = __raw_readl(dd->control_reg);
+	v &= dd->enable_mask;
+	v >>= __ffs(dd->enable_mask);
+
+	if (cpu_is_omap24xx()) {
+		if (v == OMAP2XXX_EN_DPLL_LPBYPASS ||
+		    v == OMAP2XXX_EN_DPLL_FRBYPASS)
+			return dd->clk_bypass->rate;
+	} else if (cpu_is_omap34xx()) {
+		if (v == OMAP3XXX_EN_DPLL_LPBYPASS ||
+		    v == OMAP3XXX_EN_DPLL_FRBYPASS)
+			return dd->clk_bypass->rate;
+	} else if (cpu_is_omap44xx()) {
+		if (v == OMAP4XXX_EN_DPLL_LPBYPASS ||
+		    v == OMAP4XXX_EN_DPLL_FRBYPASS ||
+		    v == OMAP4XXX_EN_DPLL_MNBYPASS)
+			return dd->clk_bypass->rate;
+	}
+
+	v = __raw_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 = (long long)dd->clk_ref->rate * dpll_mult;
+	do_div(dpll_clk, dpll_div + 1);
+
+	return dpll_clk;
+}
+
+/* DPLL rate rounding code */
+
+/**
+ * omap2_dpll_set_rate_tolerance: set the error tolerance during rate rounding
+ * @clk: struct clk * of the DPLL
+ * @tolerance: maximum rate error tolerance
+ *
+ * Set the maximum DPLL rate error tolerance for the rate rounding
+ * algorithm.  The rate tolerance is an attempt to balance DPLL power
+ * saving (the least divider value "n") vs. rate fidelity (the least
+ * difference between the desired DPLL target rate and the rounded
+ * rate out of the algorithm).  So, increasing the tolerance is likely
+ * to decrease DPLL power consumption and increase DPLL rate error.
+ * Returns -EINVAL if provided a null clock ptr or a clk that is not a
+ * DPLL; or 0 upon success.
+ */
+int omap2_dpll_set_rate_tolerance(struct clk *clk, unsigned int tolerance)
+{
+	if (!clk || !clk->dpll_data)
+		return -EINVAL;
+
+	clk->dpll_data->rate_tolerance = tolerance;
+
+	return 0;
+}
+
+/**
+ * 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, a desired target rate, and a rate tolerance, round
+ * the target rate to a possible, programmable rate for this DPLL.
+ * Rate tolerance is assumed to be set by the caller before this
+ * function is called.  Attempts to select the minimum possible n
+ * within the tolerance to reduce power consumption.  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, either because the rate is
+ * too low or because the rate tolerance is set too tightly; or the
+ * rounded rate upon success.
+ */
+long omap2_dpll_round_rate(struct clk *clk, unsigned long target_rate)
+{
+	int m, n, r, e, scaled_max_m;
+	unsigned long scaled_rt_rp, new_rate;
+	int min_e = -1, min_e_m = -1, min_e_n = -1;
+	struct dpll_data *dd;
+
+	if (!clk || !clk->dpll_data)
+		return ~0;
+
+	dd = clk->dpll_data;
+
+	pr_debug("clock: starting DPLL round_rate for clock %s, target rate "
+		 "%ld\n", clk->name, target_rate);
+
+	scaled_rt_rp = target_rate / (dd->clk_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,
+				    dd->clk_ref->rate);
+
+		/* m can't be set low enough for this n - try with a larger n */
+		if (r == DPLL_MULT_UNDERFLOW)
+			continue;
+
+		e = target_rate - new_rate;
+		pr_debug("clock: n = %d: m = %d: rate error is %d "
+			 "(new_rate = %ld)\n", n, m, e, new_rate);
+
+		if (min_e == -1 ||
+		    min_e >= (int)(abs(e) - dd->rate_tolerance)) {
+			min_e = e;
+			min_e_m = m;
+			min_e_n = n;
+
+			pr_debug("clock: found new least error %d\n", min_e);
+
+			/* We found good settings -- bail out now */
+			if (min_e <= dd->rate_tolerance)
+				break;
+		}
+	}
+
+	if (min_e < 0) {
+		pr_debug("clock: error: target rate or tolerance too low\n");
+		return ~0;
+	}
+
+	dd->last_rounded_m = min_e_m;
+	dd->last_rounded_n = min_e_n;
+	dd->last_rounded_rate = _dpll_compute_new_rate(dd->clk_ref->rate,
+						       min_e_m,  min_e_n);
+
+	pr_debug("clock: final least error: e = %d, m = %d, n = %d\n",
+		 min_e, min_e_m, min_e_n);
+	pr_debug("clock: final rate: %ld  (target rate: %ld)\n",
+		 dd->last_rounded_rate, target_rate);
+
+	return dd->last_rounded_rate;
+}
+