[v8,4/5] clk: imx: add imx composite clock

Commit Message

Abel Vesa Sept. 21, 2018, 12:11 p.m. UTC

Since a lot of clocks on imx8 are formed by a mux, gate, predivider and
divider, the idea here is to combine all of those into one composite clock,
but we need to deal with both predivider and divider at the same time and
therefore we add the imx_clk_composite_divider_ops and register the composite
clock with those.

Signed-off-by: Abel Vesa <[e-mail]>
Suggested-by: Sascha Hauer <[e-mail]>
---
 drivers/clk/imx/Makefile        |   1 +
 drivers/clk/imx/clk-composite.c | 156 ++++++++++++++++++++++++++++++++++++++++
 drivers/clk/imx/clk.h           |  14 ++++
 3 files changed, 171 insertions(+)
 create mode 100644 drivers/clk/imx/clk-composite.c

Comments

Sascha Hauer Sept. 24, 2018, 6:47 a.m. UTC | #1

Hi Abel,

On Fri, Sep 21, 2018 at 03:11:33PM +0300, Abel Vesa wrote:
> Since a lot of clocks on imx8 are formed by a mux, gate, predivider and
> divider, the idea here is to combine all of those into one composite clock,
> but we need to deal with both predivider and divider at the same time and
> therefore we add the imx_clk_composite_divider_ops and register the composite
> clock with those.
> 
> Signed-off-by: Abel Vesa <[e-mail]>
> Suggested-by: Sascha Hauer <[e-mail]>
> ---
>  drivers/clk/imx/Makefile        |   1 +
>  drivers/clk/imx/clk-composite.c | 156 ++++++++++++++++++++++++++++++++++++++++
>  drivers/clk/imx/clk.h           |  14 ++++
>  3 files changed, 171 insertions(+)
>  create mode 100644 drivers/clk/imx/clk-composite.c
> 
> +static int imx_clk_composite_divider_set_rate(struct clk_hw *hw,
> +					unsigned long rate,
> +					unsigned long parent_rate)
> +{
> +	struct clk_divider *divider = to_clk_divider(hw);
> +	unsigned long prediv_rate;
> +	unsigned long flags = 0;
> +	int prediv_value;
> +	int div_value;
> +	u32 val;
> +
> +	prediv_value = divider_get_val(rate, parent_rate, NULL,
> +				PCG_PREDIV_WIDTH, CLK_DIVIDER_ROUND_CLOSEST);
> +	if (prediv_value < 0)
> +		return prediv_value;
> +
> +	prediv_rate = DIV_ROUND_UP_ULL((u64)parent_rate, prediv_value + 1);
> +
> +	div_value = divider_get_val(rate, prediv_rate, NULL,
> +				PCG_DIV_WIDTH, CLK_DIVIDER_ROUND_CLOSEST);
> +	if (div_value < 0)
> +		return div_value;

Does this work with expected accuracy? Consider the best divider you are
looking for is 9. With the above you'll end up with a predivider of 8
and a postdivider of 1 instead of the optimum divider values of 3 and 3.

I think you have to iterate over all possible divider combinations and
then use the best one found. The original divider code does this, albeit
a little obfuscated.

You have to do the same in round_rate aswell.

Sorry, I missed that when I last looked at it in v6.

Sascha

Patch

diff --git a/drivers/clk/imx/Makefile b/drivers/clk/imx/Makefile
index b87513c..4fabb0a 100644
--- a/drivers/clk/imx/Makefile
+++ b/drivers/clk/imx/Makefile
@@ -3,6 +3,7 @@ 
 obj-y += \
 	clk.o \
 	clk-busy.o \
+	clk-composite.o \
 	clk-cpu.o \
 	clk-fixup-div.o \
 	clk-fixup-mux.o \
diff --git a/drivers/clk/imx/clk-composite.c b/drivers/clk/imx/clk-composite.c
new file mode 100644
index 0000000..1f6cd6a
--- /dev/null
+++ b/drivers/clk/imx/clk-composite.c
@@ -0,0 +1,156 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2018 NXP
+ */
+
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/clk-provider.h>
+#include <linux/clk.h>
+
+#include "clk.h"
+
+#define PCG_PREDIV_SHIFT	16
+#define PCG_PREDIV_WIDTH	3
+
+#define PCG_DIV_SHIFT		0
+#define PCG_DIV_WIDTH		6
+
+#define PCG_PCS_SHIFT		24
+#define PCG_PCS_MASK		0x7
+
+#define PCG_CGC_SHIFT		28
+
+static unsigned long imx_clk_composite_divider_recalc_rate(struct clk_hw *hw,
+						unsigned long parent_rate)
+{
+	struct clk_divider *divider = to_clk_divider(hw);
+	unsigned long prediv_rate;
+	unsigned int prediv_value;
+	unsigned int div_value;
+
+	prediv_value = clk_readl(divider->reg) >> divider->shift;
+	prediv_value &= clk_div_mask(divider->width);
+
+	prediv_rate = divider_recalc_rate(hw, parent_rate, prediv_value,
+						NULL, divider->flags,
+						divider->width);
+
+	div_value = clk_readl(divider->reg) >> PCG_DIV_SHIFT;
+	div_value &= clk_div_mask(PCG_DIV_WIDTH);
+
+	return divider_recalc_rate(hw, prediv_rate, div_value, NULL,
+				   divider->flags, PCG_DIV_WIDTH);
+}
+
+static long imx_clk_composite_divider_round_rate(struct clk_hw *hw,
+						unsigned long rate,
+						unsigned long *prate)
+{
+	struct clk_divider *divider = to_clk_divider(hw);
+	unsigned long prediv_rate;
+
+	prediv_rate = divider_round_rate(hw, rate, prate, divider->table,
+				  divider->width, divider->flags);
+	return divider_round_rate(hw, rate, &prediv_rate, divider->table,
+				  PCG_DIV_WIDTH, divider->flags);
+}
+
+static int imx_clk_composite_divider_set_rate(struct clk_hw *hw,
+					unsigned long rate,
+					unsigned long parent_rate)
+{
+	struct clk_divider *divider = to_clk_divider(hw);
+	unsigned long prediv_rate;
+	unsigned long flags = 0;
+	int prediv_value;
+	int div_value;
+	u32 val;
+
+	prediv_value = divider_get_val(rate, parent_rate, NULL,
+				PCG_PREDIV_WIDTH, CLK_DIVIDER_ROUND_CLOSEST);
+	if (prediv_value < 0)
+		return prediv_value;
+
+	prediv_rate = DIV_ROUND_UP_ULL((u64)parent_rate, prediv_value + 1);
+
+	div_value = divider_get_val(rate, prediv_rate, NULL,
+				PCG_DIV_WIDTH, CLK_DIVIDER_ROUND_CLOSEST);
+	if (div_value < 0)
+		return div_value;
+
+	spin_lock_irqsave(divider->lock, flags);
+
+	val = clk_readl(divider->reg);
+	val &= ~((clk_div_mask(divider->width) << divider->shift) |
+			(clk_div_mask(PCG_DIV_WIDTH) << PCG_DIV_SHIFT));
+
+	val |= (u32)prediv_value << divider->shift;
+	val |= (u32)div_value << PCG_DIV_SHIFT;
+	clk_writel(val, divider->reg);
+
+	spin_unlock_irqrestore(divider->lock, flags);
+
+	return 0;
+}
+
+static const struct clk_ops imx_clk_composite_divider_ops = {
+	.recalc_rate = imx_clk_composite_divider_recalc_rate,
+	.round_rate = imx_clk_composite_divider_round_rate,
+	.set_rate = imx_clk_composite_divider_set_rate,
+};
+
+struct clk *imx_clk_composite_flags(const char *name,
+					const char **parent_names,
+					int num_parents, void __iomem *reg,
+					unsigned long flags)
+{
+	struct clk_hw *mux_hw = NULL, *div_hw = NULL, *gate_hw = NULL;
+	struct clk_divider *div = NULL;
+	struct clk_gate *gate = NULL;
+	struct clk_mux *mux = NULL;
+	struct clk *clk = ERR_PTR(-ENOMEM);
+
+	mux = kzalloc(sizeof(*mux), GFP_KERNEL);
+	if (!mux)
+		goto fail;
+
+	mux_hw = &mux->hw;
+	mux->reg = reg;
+	mux->shift = PCG_PCS_SHIFT;
+	mux->mask = PCG_PCS_MASK;
+
+	div = kzalloc(sizeof(*div), GFP_KERNEL);
+	if (!div)
+		goto fail;
+
+	div_hw = &div->hw;
+	div->reg = reg;
+	div->shift = PCG_PREDIV_SHIFT;
+	div->width = PCG_PREDIV_WIDTH;
+	div->lock = &imx_ccm_lock;
+	div->flags = CLK_DIVIDER_ROUND_CLOSEST;
+
+	gate = kzalloc(sizeof(*gate), GFP_KERNEL);
+	if (!gate)
+		goto fail;
+
+	gate_hw = &gate->hw;
+	gate->reg = reg;
+	gate->bit_idx = PCG_CGC_SHIFT;
+
+	clk = clk_register_composite(NULL, name, parent_names, num_parents,
+					mux_hw, &clk_mux_ops, div_hw,
+					&imx_clk_composite_divider_ops, gate_hw,
+					&clk_gate_ops, flags);
+	if (IS_ERR(clk))
+		goto fail;
+
+	return clk;
+
+fail:
+	kfree(gate);
+	kfree(div);
+	kfree(mux);
+	return clk;
+}
diff --git a/drivers/clk/imx/clk.h b/drivers/clk/imx/clk.h
index 12b3fd6..9d7c9c8 100644
--- a/drivers/clk/imx/clk.h
+++ b/drivers/clk/imx/clk.h
@@ -232,4 +232,18 @@  struct clk *imx_clk_cpu(const char *name, const char *parent_name,
 		struct clk *div, struct clk *mux, struct clk *pll,
 		struct clk *step);
 
+struct clk *imx_clk_composite_flags(const char *name, const char **parent_names,
+		int num_parents, void __iomem *reg, unsigned long flags);
+
+#define __imx_clk_composite(name, parent_names, reg, flags) \
+	imx_clk_composite_flags(name, parent_names, \
+		ARRAY_SIZE(parent_names), reg, \
+		flags | CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE)
+
+#define imx_clk_composite(name, parent_names, reg) \
+	__imx_clk_composite(name, parent_names, reg, 0)
+
+#define imx_clk_composite_critical(name, parent_names, reg) \
+	__imx_clk_composite(name, parent_names, reg, CLK_IS_CRITICAL)
+
 #endif