1 files changed, 144 insertions, 0 deletions
diff --git a/drivers/clk/meson/clk-audio-divider.c b/drivers/clk/meson/clk-audio-divider.c
new file mode 100644
index 000000000000..6c07db06642d
--- /dev/null
+++ b/drivers/clk/meson/clk-audio-divider.c
@@ -0,0 +1,144 @@
+/*
+ * Copyright (c) 2017 AmLogic, Inc.
+ * Author: Jerome Brunet <jbrunet@baylibre.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * i2s master clock divider: The algorithm of the generic clk-divider used with
+ * a very precise clock parent such as the mpll tends to select a low divider
+ * factor. This gives poor results with this particular divider, especially with
+ * high frequencies (> 100 MHz)
+ *
+ * This driver try to select the maximum possible divider with the rate the
+ * upstream clock can provide.
+ */
+
+#include <linux/clk-provider.h>
+#include "clkc.h"
+
+#define to_meson_clk_audio_divider(_hw) container_of(_hw, \
+				struct meson_clk_audio_divider, hw)
+
+static int _div_round(unsigned long parent_rate, unsigned long rate,
+		      unsigned long flags)
+{
+	if (flags & CLK_DIVIDER_ROUND_CLOSEST)
+		return DIV_ROUND_CLOSEST_ULL((u64)parent_rate, rate);
+
+	return DIV_ROUND_UP_ULL((u64)parent_rate, rate);
+}
+
+static int _get_val(unsigned long parent_rate, unsigned long rate)
+{
+	return DIV_ROUND_UP_ULL((u64)parent_rate, rate) - 1;
+}
+
+static int _valid_divider(struct clk_hw *hw, int divider)
+{
+	struct meson_clk_audio_divider *adiv =
+		to_meson_clk_audio_divider(hw);
+	int max_divider;
+	u8 width;
+
+	width = adiv->div.width;
+	max_divider = 1 << width;
+
+	return clamp(divider, 1, max_divider);
+}
+
+static unsigned long audio_divider_recalc_rate(struct clk_hw *hw,
+					       unsigned long parent_rate)
+{
+	struct meson_clk_audio_divider *adiv =
+		to_meson_clk_audio_divider(hw);
+	struct parm *p;
+	unsigned long reg, divider;
+
+	p = &adiv->div;
+	reg = readl(adiv->base + p->reg_off);
+	divider = PARM_GET(p->width, p->shift, reg) + 1;
+
+	return DIV_ROUND_UP_ULL((u64)parent_rate, divider);
+}
+
+static long audio_divider_round_rate(struct clk_hw *hw,
+				     unsigned long rate,
+				     unsigned long *parent_rate)
+{
+	struct meson_clk_audio_divider *adiv =
+		to_meson_clk_audio_divider(hw);
+	unsigned long max_prate;
+	int divider;
+
+	if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
+		divider = _div_round(*parent_rate, rate, adiv->flags);
+		divider = _valid_divider(hw, divider);
+		return DIV_ROUND_UP_ULL((u64)*parent_rate, divider);
+	}
+
+	/* Get the maximum parent rate */
+	max_prate = clk_hw_round_rate(clk_hw_get_parent(hw), ULONG_MAX);
+
+	/* Get the corresponding rounded down divider */
+	divider = max_prate / rate;
+	divider = _valid_divider(hw, divider);
+
+	/* Get actual rate of the parent */
+	*parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw),
+					 divider * rate);
+
+	return DIV_ROUND_UP_ULL((u64)*parent_rate, divider);
+}
+
+static int audio_divider_set_rate(struct clk_hw *hw,
+				  unsigned long rate,
+				  unsigned long parent_rate)
+{
+	struct meson_clk_audio_divider *adiv =
+		to_meson_clk_audio_divider(hw);
+	struct parm *p;
+	unsigned long reg, flags = 0;
+	int val;
+
+	val = _get_val(parent_rate, rate);
+
+	if (adiv->lock)
+		spin_lock_irqsave(adiv->lock, flags);
+	else
+		__acquire(adiv->lock);
+
+	p = &adiv->div;
+	reg = readl(adiv->base + p->reg_off);
+	reg = PARM_SET(p->width, p->shift, reg, val);
+	writel(reg, adiv->base + p->reg_off);
+
+	if (adiv->lock)
+		spin_unlock_irqrestore(adiv->lock, flags);
+	else
+		__release(adiv->lock);
+
+	return 0;
+}
+
+const struct clk_ops meson_clk_audio_divider_ro_ops = {
+	.recalc_rate	= audio_divider_recalc_rate,
+	.round_rate	= audio_divider_round_rate,
+};
+
+const struct clk_ops meson_clk_audio_divider_ops = {
+	.recalc_rate	= audio_divider_recalc_rate,
+	.round_rate	= audio_divider_round_rate,
+	.set_rate	= audio_divider_set_rate,
+};