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Subject[PATCH v3 3/4] clk: rockchip: add support for half divider
Date
The new Rockchip socs have optional half divider:
The formula is shown as:
freq_out = 2*freq_in / (2*div + 3)
Is this the same for all of new SoCs.

So we use "branch_half_divider" + "COMPOSITE_NOMUX_HALFDIV \
DIV_HALF \ COMPOSITE_HALFDIV \ CMPOSITE_NOGATE_HALFDIV"
to hook that special divider clock-type into our clock-tree.

Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
---
drivers/clk/rockchip/Makefile | 1 +
drivers/clk/rockchip/clk-half-divider.c | 230 ++++++++++++++++++++++++++++++++
drivers/clk/rockchip/clk.c | 10 ++
drivers/clk/rockchip/clk.h | 85 ++++++++++++
4 files changed, 326 insertions(+)
create mode 100644 drivers/clk/rockchip/clk-half-divider.c

diff --git a/drivers/clk/rockchip/Makefile b/drivers/clk/rockchip/Makefile
index 59b8d320960a..2b380fafd232 100644
--- a/drivers/clk/rockchip/Makefile
+++ b/drivers/clk/rockchip/Makefile
@@ -7,6 +7,7 @@ obj-y += clk-rockchip.o
obj-y += clk.o
obj-y += clk-pll.o
obj-y += clk-cpu.o
+obj-y += clk-half-divider.o
obj-y += clk-inverter.o
obj-y += clk-mmc-phase.o
obj-y += clk-muxgrf.o
diff --git a/drivers/clk/rockchip/clk-half-divider.c b/drivers/clk/rockchip/clk-half-divider.c
new file mode 100644
index 000000000000..fb7a6501e0c1
--- /dev/null
+++ b/drivers/clk/rockchip/clk-half-divider.c
@@ -0,0 +1,230 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018 Fuzhou Rockchip Electronics Co., Ltd
+ */
+
+#include <linux/slab.h>
+#include <linux/bitops.h>
+#include <linux/regmap.h>
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include "clk.h"
+
+#define div_mask(width) ((1 << (width)) - 1)
+
+static bool _is_best_half_div(unsigned long rate, unsigned long now,
+ unsigned long best, unsigned long flags)
+{
+ if (flags & CLK_DIVIDER_ROUND_CLOSEST)
+ return abs(rate - now) < abs(rate - best);
+
+ return now <= rate && now > best;
+}
+
+static unsigned long clk_half_divider_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ struct clk_divider *divider = to_clk_divider(hw);
+ unsigned int val;
+
+ val = clk_readl(divider->reg) >> divider->shift;
+ val &= div_mask(divider->width);
+ val = val * 2 + 3;
+
+ return DIV_ROUND_UP_ULL(((u64)parent_rate * 2), val);
+}
+
+static int clk_half_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
+ unsigned long *best_parent_rate, u8 width,
+ unsigned long flags)
+{
+ unsigned int i, bestdiv = 0;
+ unsigned long parent_rate, best = 0, now, maxdiv;
+ unsigned long parent_rate_saved = *best_parent_rate;
+
+ if (!rate)
+ rate = 1;
+
+ maxdiv = div_mask(width);
+
+ if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
+ parent_rate = *best_parent_rate;
+ bestdiv = DIV_ROUND_UP_ULL(((u64)parent_rate * 2), rate);
+ if (bestdiv < 3)
+ bestdiv = 0;
+ else
+ bestdiv = (bestdiv - 3) / 2;
+ bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
+ return bestdiv;
+ }
+
+ /*
+ * The maximum divider we can use without overflowing
+ * unsigned long in rate * i below
+ */
+ maxdiv = min(ULONG_MAX / rate, maxdiv);
+
+ for (i = 0; i <= maxdiv; i++) {
+ if (((u64)rate * (i * 2 + 3)) == ((u64)parent_rate_saved * 2)) {
+ /*
+ * It's the most ideal case if the requested rate can be
+ * divided from parent clock without needing to change
+ * parent rate, so return the divider immediately.
+ */
+ *best_parent_rate = parent_rate_saved;
+ return i;
+ }
+ parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw),
+ ((u64)rate * (i * 2 + 3)) / 2);
+ now = DIV_ROUND_UP_ULL(((u64)parent_rate * 2),
+ (i * 2 + 3));
+
+ if (_is_best_half_div(rate, now, best, flags)) {
+ bestdiv = i;
+ best = now;
+ *best_parent_rate = parent_rate;
+ }
+ }
+
+ if (!bestdiv) {
+ bestdiv = div_mask(width);
+ *best_parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw), 1);
+ }
+
+ return bestdiv;
+}
+
+static long clk_half_divider_round_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *prate)
+{
+ struct clk_divider *divider = to_clk_divider(hw);
+ int div;
+
+ div = clk_half_divider_bestdiv(hw, rate, prate,
+ divider->width,
+ divider->flags);
+
+ return DIV_ROUND_UP_ULL(((u64)*prate * 2), div * 2 + 3);
+}
+
+static int clk_half_divider_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long parent_rate)
+{
+ struct clk_divider *divider = to_clk_divider(hw);
+ unsigned int value;
+ unsigned long flags = 0;
+ u32 val;
+
+ value = DIV_ROUND_UP_ULL(((u64)parent_rate * 2), rate);
+ value = (value - 3) / 2;
+ value = min_t(unsigned int, value, div_mask(divider->width));
+
+ if (divider->lock)
+ spin_lock_irqsave(divider->lock, flags);
+ else
+ __acquire(divider->lock);
+
+ if (divider->flags & CLK_DIVIDER_HIWORD_MASK) {
+ val = div_mask(divider->width) << (divider->shift + 16);
+ } else {
+ val = clk_readl(divider->reg);
+ val &= ~(div_mask(divider->width) << divider->shift);
+ }
+ val |= value << divider->shift;
+ clk_writel(val, divider->reg);
+
+ if (divider->lock)
+ spin_unlock_irqrestore(divider->lock, flags);
+ else
+ __release(divider->lock);
+
+ return 0;
+}
+
+const struct clk_ops clk_half_divider_ops = {
+ .recalc_rate = clk_half_divider_recalc_rate,
+ .round_rate = clk_half_divider_round_rate,
+ .set_rate = clk_half_divider_set_rate,
+};
+EXPORT_SYMBOL_GPL(clk_half_divider_ops);
+
+/**
+ * Register a clock branch.
+ * Most clock branches have a form like
+ *
+ * src1 --|--\
+ * |M |--[GATE]-[DIV]-
+ * src2 --|--/
+ *
+ * sometimes without one of those components.
+ */
+struct clk *rockchip_clk_register_halfdiv(const char *name,
+ const char *const *parent_names,
+ u8 num_parents, void __iomem *base,
+ int muxdiv_offset, u8 mux_shift,
+ u8 mux_width, u8 mux_flags,
+ u8 div_shift, u8 div_width,
+ u8 div_flags, int gate_offset,
+ u8 gate_shift, u8 gate_flags,
+ unsigned long flags,
+ spinlock_t *lock)
+{
+ struct clk *clk;
+ struct clk_mux *mux = NULL;
+ struct clk_gate *gate = NULL;
+ struct clk_divider *div = NULL;
+ const struct clk_ops *mux_ops = NULL, *div_ops = NULL,
+ *gate_ops = NULL;
+
+ if (num_parents > 1) {
+ mux = kzalloc(sizeof(*mux), GFP_KERNEL);
+ if (!mux)
+ return ERR_PTR(-ENOMEM);
+
+ mux->reg = base + muxdiv_offset;
+ mux->shift = mux_shift;
+ mux->mask = BIT(mux_width) - 1;
+ mux->flags = mux_flags;
+ mux->lock = lock;
+ mux_ops = (mux_flags & CLK_MUX_READ_ONLY) ? &clk_mux_ro_ops
+ : &clk_mux_ops;
+ }
+
+ if (gate_offset >= 0) {
+ gate = kzalloc(sizeof(*gate), GFP_KERNEL);
+ if (!gate)
+ goto err_gate;
+
+ gate->flags = gate_flags;
+ gate->reg = base + gate_offset;
+ gate->bit_idx = gate_shift;
+ gate->lock = lock;
+ gate_ops = &clk_gate_ops;
+ }
+
+ if (div_width > 0) {
+ div = kzalloc(sizeof(*div), GFP_KERNEL);
+ if (!div)
+ goto err_div;
+
+ div->flags = div_flags;
+ div->reg = base + muxdiv_offset;
+ div->shift = div_shift;
+ div->width = div_width;
+ div->lock = lock;
+ div_ops = &clk_half_divider_ops;
+ }
+
+ clk = clk_register_composite(NULL, name, parent_names, num_parents,
+ mux ? &mux->hw : NULL, mux_ops,
+ div ? &div->hw : NULL, div_ops,
+ gate ? &gate->hw : NULL, gate_ops,
+ flags);
+
+ return clk;
+err_div:
+ kfree(gate);
+err_gate:
+ kfree(mux);
+ return ERR_PTR(-ENOMEM);
+}
diff --git a/drivers/clk/rockchip/clk.c b/drivers/clk/rockchip/clk.c
index 3cd8ad59e0b7..cd1474c05c91 100644
--- a/drivers/clk/rockchip/clk.c
+++ b/drivers/clk/rockchip/clk.c
@@ -498,6 +498,16 @@ void __init rockchip_clk_register_branches(
list->gate_flags, flags, list->child,
&ctx->lock);
break;
+ case branch_half_divider:
+ clk = rockchip_clk_register_halfdiv(list->name,
+ list->parent_names, list->num_parents,
+ ctx->reg_base, list->muxdiv_offset,
+ list->mux_shift, list->mux_width,
+ list->mux_flags, list->div_shift,
+ list->div_width, list->div_flags,
+ list->gate_offset, list->gate_shift,
+ list->gate_flags, flags, &ctx->lock);
+ break;
case branch_gate:
flags |= CLK_SET_RATE_PARENT;

diff --git a/drivers/clk/rockchip/clk.h b/drivers/clk/rockchip/clk.h
index ef601dded32c..23c569a875d4 100644
--- a/drivers/clk/rockchip/clk.h
+++ b/drivers/clk/rockchip/clk.h
@@ -354,6 +354,7 @@ enum rockchip_clk_branch_type {
branch_inverter,
branch_factor,
branch_ddrclk,
+ branch_half_divider,
};

struct rockchip_clk_branch {
@@ -684,6 +685,79 @@ struct rockchip_clk_branch {
.gate_flags = gf, \
}

+#define COMPOSITE_HALFDIV(_id, cname, pnames, f, mo, ms, mw, mf, ds, dw,\
+ df, go, gs, gf) \
+ { \
+ .id = _id, \
+ .branch_type = branch_half_divider, \
+ .name = cname, \
+ .parent_names = pnames, \
+ .num_parents = ARRAY_SIZE(pnames), \
+ .flags = f, \
+ .muxdiv_offset = mo, \
+ .mux_shift = ms, \
+ .mux_width = mw, \
+ .mux_flags = mf, \
+ .div_shift = ds, \
+ .div_width = dw, \
+ .div_flags = df, \
+ .gate_offset = go, \
+ .gate_shift = gs, \
+ .gate_flags = gf, \
+ }
+
+#define COMPOSITE_NOGATE_HALFDIV(_id, cname, pnames, f, mo, ms, mw, mf, \
+ ds, dw, df) \
+ { \
+ .id = _id, \
+ .branch_type = branch_half_divider, \
+ .name = cname, \
+ .parent_names = pnames, \
+ .num_parents = ARRAY_SIZE(pnames), \
+ .flags = f, \
+ .muxdiv_offset = mo, \
+ .mux_shift = ms, \
+ .mux_width = mw, \
+ .mux_flags = mf, \
+ .div_shift = ds, \
+ .div_width = dw, \
+ .div_flags = df, \
+ .gate_offset = -1, \
+ }
+
+#define COMPOSITE_NOMUX_HALFDIV(_id, cname, pname, f, mo, ds, dw, df, \
+ go, gs, gf) \
+ { \
+ .id = _id, \
+ .branch_type = branch_half_divider, \
+ .name = cname, \
+ .parent_names = (const char *[]){ pname }, \
+ .num_parents = 1, \
+ .flags = f, \
+ .muxdiv_offset = mo, \
+ .div_shift = ds, \
+ .div_width = dw, \
+ .div_flags = df, \
+ .gate_offset = go, \
+ .gate_shift = gs, \
+ .gate_flags = gf, \
+ }
+
+#define DIV_HALF(_id, cname, pname, f, o, s, w, df) \
+ { \
+ .id = _id, \
+ .branch_type = branch_half_divider, \
+ .name = cname, \
+ .parent_names = (const char *[]){ pname }, \
+ .num_parents = 1, \
+ .flags = f, \
+ .muxdiv_offset = o, \
+ .div_shift = s, \
+ .div_width = w, \
+ .div_flags = df, \
+ .gate_offset = -1, \
+ }
+
struct rockchip_clk_provider *rockchip_clk_init(struct device_node *np,
void __iomem *base, unsigned long nr_clks);
void rockchip_clk_of_add_provider(struct device_node *np,
@@ -708,6 +782,17 @@ void rockchip_register_restart_notifier(struct rockchip_clk_provider *ctx,

#define ROCKCHIP_SOFTRST_HIWORD_MASK BIT(0)

+struct clk *rockchip_clk_register_halfdiv(const char *name,
+ const char *const *parent_names,
+ u8 num_parents, void __iomem *base,
+ int muxdiv_offset, u8 mux_shift,
+ u8 mux_width, u8 mux_flags,
+ u8 div_shift, u8 div_width,
+ u8 div_flags, int gate_offset,
+ u8 gate_shift, u8 gate_flags,
+ unsigned long flags,
+ spinlock_t *lock);
+
#ifdef CONFIG_RESET_CONTROLLER
void rockchip_register_softrst(struct device_node *np,
unsigned int num_regs,
--
1.9.1

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