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path: root/drivers/clk/meson/clk-audio-divider.c
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Diffstat (limited to 'drivers/clk/meson/clk-audio-divider.c')
-rw-r--r--drivers/clk/meson/clk-audio-divider.c144
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 0000000..6c07db0
--- /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,
+};