1 files changed, 449 insertions, 0 deletions

diff --git a/drivers/clk/meson/clk-pll.c b/drivers/clk/meson/clk-pll.c
new file mode 100644
index 000000000..49f27fe53
--- /dev/null
+++ b/drivers/clk/meson/clk-pll.c
@@ -0,0 +1,449 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2015 Endless Mobile, Inc.
+ * Author: Carlo Caione <carlo@endlessm.com>
+ *
+ * Copyright (c) 2018 Baylibre, SAS.
+ * Author: Jerome Brunet <jbrunet@baylibre.com>
+ */
+
+/*
+ * In the most basic form, a Meson PLL is composed as follows:
+ *
+ *                     PLL
+ *        +--------------------------------+
+ *        |                                |
+ *        |             +--+               |
+ *  in >>-----[ /N ]--->|  |      +-----+  |
+ *        |             |  |------| DCO |---->> out
+ *        |  +--------->|  |      +--v--+  |
+ *        |  |          +--+         |     |
+ *        |  |                       |     |
+ *        |  +--[ *(M + (F/Fmax) ]<--+     |
+ *        |                                |
+ *        +--------------------------------+
+ *
+ * out = in * (m + frac / frac_max) / n
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/rational.h>
+
+#include "clk-regmap.h"
+#include "clk-pll.h"
+
+static inline struct meson_clk_pll_data *
+meson_clk_pll_data(struct clk_regmap *clk)
+{
+	return (struct meson_clk_pll_data *)clk->data;
+}
+
+static int __pll_round_closest_mult(struct meson_clk_pll_data *pll)
+{
+	if ((pll->flags & CLK_MESON_PLL_ROUND_CLOSEST) &&
+	    !MESON_PARM_APPLICABLE(&pll->frac))
+		return 1;
+
+	return 0;
+}
+
+static unsigned long __pll_params_to_rate(unsigned long parent_rate,
+					  unsigned int m, unsigned int n,
+					  unsigned int frac,
+					  struct meson_clk_pll_data *pll)
+{
+	u64 rate = (u64)parent_rate * m;
+
+	if (frac && MESON_PARM_APPLICABLE(&pll->frac)) {
+		u64 frac_rate = (u64)parent_rate * frac;
+
+		rate += DIV_ROUND_UP_ULL(frac_rate,
+					 (1 << pll->frac.width));
+	}
+
+	return DIV_ROUND_UP_ULL(rate, n);
+}
+
+static unsigned long meson_clk_pll_recalc_rate(struct clk_hw *hw,
+						unsigned long parent_rate)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
+	unsigned int m, n, frac;
+
+	n = meson_parm_read(clk->map, &pll->n);
+
+	/*
+	 * On some HW, N is set to zero on init. This value is invalid as
+	 * it would result in a division by zero. The rate can't be
+	 * calculated in this case
+	 */
+	if (n == 0)
+		return 0;
+
+	m = meson_parm_read(clk->map, &pll->m);
+
+	frac = MESON_PARM_APPLICABLE(&pll->frac) ?
+		meson_parm_read(clk->map, &pll->frac) :
+		0;
+
+	return __pll_params_to_rate(parent_rate, m, n, frac, pll);
+}
+
+static unsigned int __pll_params_with_frac(unsigned long rate,
+					   unsigned long parent_rate,
+					   unsigned int m,
+					   unsigned int n,
+					   struct meson_clk_pll_data *pll)
+{
+	unsigned int frac_max = (1 << pll->frac.width);
+	u64 val = (u64)rate * n;
+
+	/* Bail out if we are already over the requested rate */
+	if (rate < parent_rate * m / n)
+		return 0;
+
+	if (pll->flags & CLK_MESON_PLL_ROUND_CLOSEST)
+		val = DIV_ROUND_CLOSEST_ULL(val * frac_max, parent_rate);
+	else
+		val = div_u64(val * frac_max, parent_rate);
+
+	val -= m * frac_max;
+
+	return min((unsigned int)val, (frac_max - 1));
+}
+
+static bool meson_clk_pll_is_better(unsigned long rate,
+				    unsigned long best,
+				    unsigned long now,
+				    struct meson_clk_pll_data *pll)
+{
+	if (__pll_round_closest_mult(pll)) {
+		/* Round Closest */
+		if (abs(now - rate) < abs(best - rate))
+			return true;
+	} else {
+		/* Round down */
+		if (now <= rate && best < now)
+			return true;
+	}
+
+	return false;
+}
+
+static int meson_clk_get_pll_table_index(unsigned int index,
+					 unsigned int *m,
+					 unsigned int *n,
+					 struct meson_clk_pll_data *pll)
+{
+	if (!pll->table[index].n)
+		return -EINVAL;
+
+	*m = pll->table[index].m;
+	*n = pll->table[index].n;
+
+	return 0;
+}
+
+static unsigned int meson_clk_get_pll_range_m(unsigned long rate,
+					      unsigned long parent_rate,
+					      unsigned int n,
+					      struct meson_clk_pll_data *pll)
+{
+	u64 val = (u64)rate * n;
+
+	if (__pll_round_closest_mult(pll))
+		return DIV_ROUND_CLOSEST_ULL(val, parent_rate);
+
+	return div_u64(val,  parent_rate);
+}
+
+static int meson_clk_get_pll_range_index(unsigned long rate,
+					 unsigned long parent_rate,
+					 unsigned int index,
+					 unsigned int *m,
+					 unsigned int *n,
+					 struct meson_clk_pll_data *pll)
+{
+	*n = index + 1;
+
+	/* Check the predivider range */
+	if (*n >= (1 << pll->n.width))
+		return -EINVAL;
+
+	if (*n == 1) {
+		/* Get the boundaries out the way */
+		if (rate <= pll->range->min * parent_rate) {
+			*m = pll->range->min;
+			return -ENODATA;
+		} else if (rate >= pll->range->max * parent_rate) {
+			*m = pll->range->max;
+			return -ENODATA;
+		}
+	}
+
+	*m = meson_clk_get_pll_range_m(rate, parent_rate, *n, pll);
+
+	/* the pre-divider gives a multiplier too big - stop */
+	if (*m >= (1 << pll->m.width))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int meson_clk_get_pll_get_index(unsigned long rate,
+				       unsigned long parent_rate,
+				       unsigned int index,
+				       unsigned int *m,
+				       unsigned int *n,
+				       struct meson_clk_pll_data *pll)
+{
+	if (pll->range)
+		return meson_clk_get_pll_range_index(rate, parent_rate,
+						     index, m, n, pll);
+	else if (pll->table)
+		return meson_clk_get_pll_table_index(index, m, n, pll);
+
+	return -EINVAL;
+}
+
+static int meson_clk_get_pll_settings(unsigned long rate,
+				      unsigned long parent_rate,
+				      unsigned int *best_m,
+				      unsigned int *best_n,
+				      struct meson_clk_pll_data *pll)
+{
+	unsigned long best = 0, now = 0;
+	unsigned int i, m, n;
+	int ret;
+
+	for (i = 0, ret = 0; !ret; i++) {
+		ret = meson_clk_get_pll_get_index(rate, parent_rate,
+						  i, &m, &n, pll);
+		if (ret == -EINVAL)
+			break;
+
+		now = __pll_params_to_rate(parent_rate, m, n, 0, pll);
+		if (meson_clk_pll_is_better(rate, best, now, pll)) {
+			best = now;
+			*best_m = m;
+			*best_n = n;
+
+			if (now == rate)
+				break;
+		}
+	}
+
+	return best ? 0 : -EINVAL;
+}
+
+static long meson_clk_pll_round_rate(struct clk_hw *hw, unsigned long rate,
+				     unsigned long *parent_rate)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
+	unsigned int m, n, frac;
+	unsigned long round;
+	int ret;
+
+	ret = meson_clk_get_pll_settings(rate, *parent_rate, &m, &n, pll);
+	if (ret)
+		return meson_clk_pll_recalc_rate(hw, *parent_rate);
+
+	round = __pll_params_to_rate(*parent_rate, m, n, 0, pll);
+
+	if (!MESON_PARM_APPLICABLE(&pll->frac) || rate == round)
+		return round;
+
+	/*
+	 * The rate provided by the setting is not an exact match, let's
+	 * try to improve the result using the fractional parameter
+	 */
+	frac = __pll_params_with_frac(rate, *parent_rate, m, n, pll);
+
+	return __pll_params_to_rate(*parent_rate, m, n, frac, pll);
+}
+
+static int meson_clk_pll_wait_lock(struct clk_hw *hw)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
+	int delay = 24000000;
+
+	do {
+		/* Is the clock locked now ? */
+		if (meson_parm_read(clk->map, &pll->l))
+			return 0;
+
+		delay--;
+	} while (delay > 0);
+
+	return -ETIMEDOUT;
+}
+
+static int meson_clk_pll_init(struct clk_hw *hw)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
+
+	if (pll->init_count) {
+		meson_parm_write(clk->map, &pll->rst, 1);
+		regmap_multi_reg_write(clk->map, pll->init_regs,
+				       pll->init_count);
+		meson_parm_write(clk->map, &pll->rst, 0);
+	}
+
+	return 0;
+}
+
+static int meson_clk_pll_is_enabled(struct clk_hw *hw)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
+
+	if (meson_parm_read(clk->map, &pll->rst) ||
+	    !meson_parm_read(clk->map, &pll->en) ||
+	    !meson_parm_read(clk->map, &pll->l))
+		return 0;
+
+	return 1;
+}
+
+static int meson_clk_pcie_pll_enable(struct clk_hw *hw)
+{
+	meson_clk_pll_init(hw);
+
+	if (meson_clk_pll_wait_lock(hw))
+		return -EIO;
+
+	return 0;
+}
+
+static int meson_clk_pll_enable(struct clk_hw *hw)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
+
+	/* do nothing if the PLL is already enabled */
+	if (clk_hw_is_enabled(hw))
+		return 0;
+
+	/* Make sure the pll is in reset */
+	meson_parm_write(clk->map, &pll->rst, 1);
+
+	/* Enable the pll */
+	meson_parm_write(clk->map, &pll->en, 1);
+
+	/* Take the pll out reset */
+	meson_parm_write(clk->map, &pll->rst, 0);
+
+	if (meson_clk_pll_wait_lock(hw))
+		return -EIO;
+
+	return 0;
+}
+
+static void meson_clk_pll_disable(struct clk_hw *hw)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
+
+	/* Put the pll is in reset */
+	meson_parm_write(clk->map, &pll->rst, 1);
+
+	/* Disable the pll */
+	meson_parm_write(clk->map, &pll->en, 0);
+}
+
+static int meson_clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
+				  unsigned long parent_rate)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
+	unsigned int enabled, m, n, frac = 0;
+	unsigned long old_rate;
+	int ret;
+
+	if (parent_rate == 0 || rate == 0)
+		return -EINVAL;
+
+	old_rate = clk_hw_get_rate(hw);
+
+	ret = meson_clk_get_pll_settings(rate, parent_rate, &m, &n, pll);
+	if (ret)
+		return ret;
+
+	enabled = meson_parm_read(clk->map, &pll->en);
+	if (enabled)
+		meson_clk_pll_disable(hw);
+
+	meson_parm_write(clk->map, &pll->n, n);
+	meson_parm_write(clk->map, &pll->m, m);
+
+	if (MESON_PARM_APPLICABLE(&pll->frac)) {
+		frac = __pll_params_with_frac(rate, parent_rate, m, n, pll);
+		meson_parm_write(clk->map, &pll->frac, frac);
+	}
+
+	/* If the pll is stopped, bail out now */
+	if (!enabled)
+		return 0;
+
+	ret = meson_clk_pll_enable(hw);
+	if (ret) {
+		pr_warn("%s: pll did not lock, trying to restore old rate %lu\n",
+			__func__, old_rate);
+		/*
+		 * FIXME: Do we really need/want this HACK ?
+		 * It looks unsafe. what happens if the clock gets into a
+		 * broken state and we can't lock back on the old_rate ? Looks
+		 * like an infinite recursion is possible
+		 */
+		meson_clk_pll_set_rate(hw, old_rate, parent_rate);
+	}
+
+	return ret;
+}
+
+/*
+ * The Meson G12A PCIE PLL is fined tuned to deliver a very precise
+ * 100MHz reference clock for the PCIe Analog PHY, and thus requires
+ * a strict register sequence to enable the PLL.
+ * To simplify, re-use the _init() op to enable the PLL and keep
+ * the other ops except set_rate since the rate is fixed.
+ */
+const struct clk_ops meson_clk_pcie_pll_ops = {
+	.recalc_rate	= meson_clk_pll_recalc_rate,
+	.round_rate	= meson_clk_pll_round_rate,
+	.is_enabled	= meson_clk_pll_is_enabled,
+	.enable		= meson_clk_pcie_pll_enable,
+	.disable	= meson_clk_pll_disable
+};
+EXPORT_SYMBOL_GPL(meson_clk_pcie_pll_ops);
+
+const struct clk_ops meson_clk_pll_ops = {
+	.init		= meson_clk_pll_init,
+	.recalc_rate	= meson_clk_pll_recalc_rate,
+	.round_rate	= meson_clk_pll_round_rate,
+	.set_rate	= meson_clk_pll_set_rate,
+	.is_enabled	= meson_clk_pll_is_enabled,
+	.enable		= meson_clk_pll_enable,
+	.disable	= meson_clk_pll_disable
+};
+EXPORT_SYMBOL_GPL(meson_clk_pll_ops);
+
+const struct clk_ops meson_clk_pll_ro_ops = {
+	.recalc_rate	= meson_clk_pll_recalc_rate,
+	.is_enabled	= meson_clk_pll_is_enabled,
+};
+EXPORT_SYMBOL_GPL(meson_clk_pll_ro_ops);
+
+MODULE_DESCRIPTION("Amlogic PLL driver");
+MODULE_AUTHOR("Carlo Caione <carlo@endlessm.com>");
+MODULE_AUTHOR("Jerome Brunet <jbrunet@baylibre.com>");
+MODULE_LICENSE("GPL v2");