[PATCH 07/16] clk: sunxi-ng: Add phase clock support

Maxime Ripard
2016-05-08T20:01:42Z

Add support for the clocks in the CCU that introduce a phase shift from
their parent clock.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
---
drivers/clk/sunxi-ng/Makefile | 1 +
drivers/clk/sunxi-ng/ccu_phase.c | 126 +++++++++++++++++++++++++++++++++++++++
drivers/clk/sunxi-ng/ccu_phase.h | 50 ++++++++++++++++
3 files changed, 177 insertions(+)
create mode 100644 drivers/clk/sunxi-ng/ccu_phase.c
create mode 100644 drivers/clk/sunxi-ng/ccu_phase.h

diff --git a/drivers/clk/sunxi-ng/Makefile b/drivers/clk/sunxi-ng/Makefile
index f20c6c8f217c..a47a3bbdf285 100644
--- a/drivers/clk/sunxi-ng/Makefile
+++ b/drivers/clk/sunxi-ng/Makefile
@@ -5,3 +5,4 @@ obj-y += ccu_div_table.o
obj-y += ccu_fixed_factor.o
obj-y += ccu_gate.o
obj-y += ccu_mux.o
+obj-y += ccu_phase.o
diff --git a/drivers/clk/sunxi-ng/ccu_phase.c b/drivers/clk/sunxi-ng/ccu_phase.c
new file mode 100644
index 000000000000..cf0f0b20115c
--- /dev/null
+++ b/drivers/clk/sunxi-ng/ccu_phase.c
@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2016 Maxime Ripard
+ * Maxime Ripard <maxime.ripard@free-electrons.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ */
+
+#include <linux/clk-provider.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, *pparent;
+ unsigned int parent_rate, pparent_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) */
+ pparent = clk_hw_get_parent(parent);
+ if (!pparent)
+ return -EINVAL;
+
+ /* And its rate */
+ pparent_rate = clk_hw_get_rate(pparent);
+ if (!pparent_rate)
+ return -EINVAL;
+
+ /* Get our parent clock divider */
+ parent_div = pparent_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, *pparent;
+ unsigned int parent_rate, pparent_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) */
+ pparent = clk_hw_get_parent(parent);
+ if (!pparent)
+ return -EINVAL;
+
+ /* And its rate */
+ pparent_rate = clk_hw_get_rate(pparent);
+ if (!pparent_rate)
+ return -EINVAL;
+
+ if (degrees != 180) {
+ u16 step, parent_div;
+
+ /* Get our parent divider */
+ parent_div = pparent_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, 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,
+};
diff --git a/drivers/clk/sunxi-ng/ccu_phase.h b/drivers/clk/sunxi-ng/ccu_phase.h
new file mode 100644
index 000000000000..e28b4e58a819
--- /dev/null
+++ b/drivers/clk/sunxi-ng/ccu_phase.h
@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2016 Maxime Ripard. All rights reserved.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#ifndef _CCU_PHASE_H_
+#define _CCU_PHASE_H_
+
+#include <linux/clk-provider.h>
+
+#include "ccu_common.h"
+
+struct ccu_phase {
+ u8 shift;
+ u8 width;
+
+ struct ccu_common common;
+};
+
+#define SUNXI_CCU_PHASE(_struct, _name, _parent, _reg, _shift, _width, _flags) \
+ struct ccu_phase _struct = { \
+ .shift = _shift, \
+ .width = _width, \
+ .common = { \
+ .reg = _reg, \
+ .hw.init = SUNXI_HW_INIT(_name, \
+ _parent, \
+ &ccu_phase_ops, \
+ _flags), \
+ } \
+ }
+
+static inline struct ccu_phase *hw_to_ccu_phase(struct clk_hw *hw)
+{
+ struct ccu_common *common = hw_to_ccu_common(hw);
+
+ return container_of(common, struct ccu_phase, common);
+}
+
+extern const struct clk_ops ccu_phase_ops;
+
+#endif /* _CCU_PHASE_H_ */
--
2.8.2