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path: root/drivers/clk/sunxi-ng/ccu_phase.c
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-rw-r--r--drivers/clk/sunxi-ng/ccu_phase.c124
1 files changed, 124 insertions, 0 deletions
diff --git a/drivers/clk/sunxi-ng/ccu_phase.c b/drivers/clk/sunxi-ng/ccu_phase.c
new file mode 100644
index 000000000..e4cae2afe
--- /dev/null
+++ b/drivers/clk/sunxi-ng/ccu_phase.c
@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2016 Maxime Ripard
+ * Maxime Ripard <maxime.ripard@free-electrons.com>
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/io.h>
+#include <linux/spinlock.h>
+
+#include "ccu_phase.h"
+
+static int ccu_phase_get_phase(struct clk_hw *hw)
+{
+ struct ccu_phase *phase = hw_to_ccu_phase(hw);
+ struct clk_hw *parent, *grandparent;
+ unsigned int parent_rate, grandparent_rate;
+ u16 step, parent_div;
+ u32 reg;
+ u8 delay;
+
+ reg = readl(phase->common.base + phase->common.reg);
+ delay = (reg >> phase->shift);
+ delay &= (1 << phase->width) - 1;
+
+ if (!delay)
+ return 180;
+
+ /* Get our parent clock, it's the one that can adjust its rate */
+ parent = clk_hw_get_parent(hw);
+ if (!parent)
+ return -EINVAL;
+
+ /* And its rate */
+ parent_rate = clk_hw_get_rate(parent);
+ if (!parent_rate)
+ return -EINVAL;
+
+ /* Now, get our parent's parent (most likely some PLL) */
+ grandparent = clk_hw_get_parent(parent);
+ if (!grandparent)
+ return -EINVAL;
+
+ /* And its rate */
+ grandparent_rate = clk_hw_get_rate(grandparent);
+ if (!grandparent_rate)
+ return -EINVAL;
+
+ /* Get our parent clock divider */
+ parent_div = grandparent_rate / parent_rate;
+
+ step = DIV_ROUND_CLOSEST(360, parent_div);
+ return delay * step;
+}
+
+static int ccu_phase_set_phase(struct clk_hw *hw, int degrees)
+{
+ struct ccu_phase *phase = hw_to_ccu_phase(hw);
+ struct clk_hw *parent, *grandparent;
+ unsigned int parent_rate, grandparent_rate;
+ unsigned long flags;
+ u32 reg;
+ u8 delay;
+
+ /* Get our parent clock, it's the one that can adjust its rate */
+ parent = clk_hw_get_parent(hw);
+ if (!parent)
+ return -EINVAL;
+
+ /* And its rate */
+ parent_rate = clk_hw_get_rate(parent);
+ if (!parent_rate)
+ return -EINVAL;
+
+ /* Now, get our parent's parent (most likely some PLL) */
+ grandparent = clk_hw_get_parent(parent);
+ if (!grandparent)
+ return -EINVAL;
+
+ /* And its rate */
+ grandparent_rate = clk_hw_get_rate(grandparent);
+ if (!grandparent_rate)
+ return -EINVAL;
+
+ if (degrees != 180) {
+ u16 step, parent_div;
+
+ /* Get our parent divider */
+ parent_div = grandparent_rate / parent_rate;
+
+ /*
+ * We can only outphase the clocks by multiple of the
+ * PLL's period.
+ *
+ * Since our parent clock is only a divider, and the
+ * formula to get the outphasing in degrees is deg =
+ * 360 * delta / period
+ *
+ * If we simplify this formula, we can see that the
+ * only thing that we're concerned about is the number
+ * of period we want to outphase our clock from, and
+ * the divider set by our parent clock.
+ */
+ step = DIV_ROUND_CLOSEST(360, parent_div);
+ delay = DIV_ROUND_CLOSEST(degrees, step);
+ } else {
+ delay = 0;
+ }
+
+ spin_lock_irqsave(phase->common.lock, flags);
+ reg = readl(phase->common.base + phase->common.reg);
+ reg &= ~GENMASK(phase->width + phase->shift - 1, phase->shift);
+ writel(reg | (delay << phase->shift),
+ phase->common.base + phase->common.reg);
+ spin_unlock_irqrestore(phase->common.lock, flags);
+
+ return 0;
+}
+
+const struct clk_ops ccu_phase_ops = {
+ .get_phase = ccu_phase_get_phase,
+ .set_phase = ccu_phase_set_phase,
+};
+EXPORT_SYMBOL_NS_GPL(ccu_phase_ops, SUNXI_CCU);