[PATCH resend v4 0/3] clk: sun6i: Unify AHB1 clock and fix rate calculation

[PATCH resend v4 0/3] clk: sun6i: Unify AHB1 clock and fix rate calculation

[Chen-Yu Tsai]

Hi everyone,

This is a resend of v4 of the sun6i AHB1 clock unification series.
This includes only the 3 patches not yet merged.

This series unifies the mux and divider parts of the AHB1 clock found
on sun6i and sun8i, while also adding support for the pre-divider on the
PLL6 input.

The rate calculation logic must factor in which parent it is using to
calculate the rate, to decide whether to use the pre-divider or not.
This is beyond the original factors clk design in sunxi. To avoid
feature bloat, this is implemented as a separate composite clk.

The new clock driver is registered with a separate OF_CLK_DECLARE.
As it shares its register with the APB1 div clock, thus shares the same
spinlock, it cannot reside in a separate file.


The contents of this series are as follows:

Patch 1 adds the unified AHB1 clock driver.

Patch 2 and 3 unify the AHB1 clock nodes on sun6i and sun8i respectively.

Changes since v3:

  - Moved AHB1 clock driver to the front of clk-sunxi.c
  
  - Dropped the following patches that were merged already:

      clk: sunxi: Specify number of child clocks for divs clocks
      clk: sunxi: Implement A31 PLL6 as a divs clock for 2x output
      ARM: sun6i: DT: Add PLL6 multiple outputs

Changes since v2:

  - Rebased onto the following patches

    clk: sunxi: Removed unused/incorrect sun6i-a31-apb2-clk driver
    ARM: dts: sunxi: Use sun4i-a10-apb1-clk for sun6i/sun8i apb2 clocks.
    ARM: dts: sunxi: unify APB1 clock
    clk: sunxi: unify APB1 clock
    ARM: dts: sun6i: Re-parent ahb1_mux to pll6 as required by dma controller

  - Dropped

    ARM: dts: sun6i: Add required ahb1 clock parent and rates for dma controller

    as it is superseded by the re-parent patch from above.

  - Expand clock bindings to include output names for PLL6

  - Use of_io_request_and_map

  - Drop ahb1 rate setting in DTS

  - Whitespace and comment style cleanups

Changes since v1:

  - Dropped "clk: sunxi: Add post clk divider for factor clocks"

  - Added "clk: sunxi: Specify number of child clocks for divs clocks"

  - Reworked the PLL6 clock into a divs clock with 2 outputs.
    This matches the style of PLL6 on the other sunxi platforms.

  - Dropped "dmaengine: sun6i: Remove obsolete clk muxing code".
    Already merged.


Cheers
ChenYu

Chen-Yu Tsai (3):
  clk: sunxi: unify sun6i AHB1 clock with proper PLL6 pre-divider
  ARM: dts: sun6i: Unify ahb1 clock nodes
  ARM: dts: sun8i: Unify ahb1 clock nodes

 Documentation/devicetree/bindings/clock/sunxi.txt |   2 +-
 arch/arm/boot/dts/sun6i-a31.dtsi                  |  14 +-
 arch/arm/boot/dts/sun8i-a23.dtsi                  |  12 +-
 drivers/clk/sunxi/clk-sunxi.c                     | 208 ++++++++++++++++++++++
 4 files changed, 214 insertions(+), 22 deletions(-)

-- 
2.1.3

[PATCH resend v4 1/3] clk: sunxi: unify sun6i AHB1 clock with proper PLL6 pre-divider

[Chen-Yu Tsai]

This patch unifies the sun6i AHB1 clock, originally supported
with separate mux and divider clks. It also adds support for
the pre-divider on the PLL6 input, thus allowing the clock to
be muxed to PLL6 with proper clock rate calculation.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
---
 Documentation/devicetree/bindings/clock/sunxi.txt |   2 +-
 drivers/clk/sunxi/clk-sunxi.c                     | 208 ++++++++++++++++++++++
 2 files changed, 209 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/clock/sunxi.txt b/Documentation/devicetree/bindings/clock/sunxi.txt
index 67b2b99..9dc4f55 100644
--- a/Documentation/devicetree/bindings/clock/sunxi.txt
+++ b/Documentation/devicetree/bindings/clock/sunxi.txt
@@ -26,7 +26,7 @@ Required properties:
 	"allwinner,sun5i-a10s-ahb-gates-clk" - for the AHB gates on A10s
 	"allwinner,sun7i-a20-ahb-gates-clk" - for the AHB gates on A20
 	"allwinner,sun6i-a31-ar100-clk" - for the AR100 on A31
-	"allwinner,sun6i-a31-ahb1-mux-clk" - for the AHB1 multiplexer on A31
+	"allwinner,sun6i-a31-ahb1-clk" - for the AHB1 clock on A31
 	"allwinner,sun6i-a31-ahb1-gates-clk" - for the AHB1 gates on A31
 	"allwinner,sun8i-a23-ahb1-gates-clk" - for the AHB1 gates on A23
 	"allwinner,sun9i-a80-ahb0-gates-clk" - for the AHB0 gates on A80
diff --git a/drivers/clk/sunxi/clk-sunxi.c b/drivers/clk/sunxi/clk-sunxi.c
index 5702025..337593c 100644
--- a/drivers/clk/sunxi/clk-sunxi.c
+++ b/drivers/clk/sunxi/clk-sunxi.c
@@ -20,11 +20,219 @@
 #include <linux/of_address.h>
 #include <linux/reset-controller.h>
 #include <linux/spinlock.h>
+#include <linux/log2.h>
 
 #include "clk-factors.h"
 
 static DEFINE_SPINLOCK(clk_lock);
 
+/**
+ * sun6i_a31_ahb1_clk_setup() - Setup function for a31 ahb1 composite clk
+ */
+
+#define SUN6I_AHB1_MAX_PARENTS		4
+#define SUN6I_AHB1_MUX_PARENT_PLL6	3
+#define SUN6I_AHB1_MUX_SHIFT		12
+/* un-shifted mask is what mux_clk expects */
+#define SUN6I_AHB1_MUX_MASK		0x3
+#define SUN6I_AHB1_MUX_GET_PARENT(reg)	((reg >> SUN6I_AHB1_MUX_SHIFT) & \
+					 SUN6I_AHB1_MUX_MASK)
+
+#define SUN6I_AHB1_DIV_SHIFT		4
+#define SUN6I_AHB1_DIV_MASK		(0x3 << SUN6I_AHB1_DIV_SHIFT)
+#define SUN6I_AHB1_DIV_GET(reg)		((reg & SUN6I_AHB1_DIV_MASK) >> \
+						SUN6I_AHB1_DIV_SHIFT)
+#define SUN6I_AHB1_DIV_SET(reg, div)	((reg & ~SUN6I_AHB1_DIV_MASK) | \
+						(div << SUN6I_AHB1_DIV_SHIFT))
+#define SUN6I_AHB1_PLL6_DIV_SHIFT	6
+#define SUN6I_AHB1_PLL6_DIV_MASK	(0x3 << SUN6I_AHB1_PLL6_DIV_SHIFT)
+#define SUN6I_AHB1_PLL6_DIV_GET(reg)	((reg & SUN6I_AHB1_PLL6_DIV_MASK) >> \
+						SUN6I_AHB1_PLL6_DIV_SHIFT)
+#define SUN6I_AHB1_PLL6_DIV_SET(reg, div) ((reg & ~SUN6I_AHB1_PLL6_DIV_MASK) | \
+						(div << SUN6I_AHB1_PLL6_DIV_SHIFT))
+
+struct sun6i_ahb1_clk {
+	struct clk_hw hw;
+	void __iomem *reg;
+};
+
+#define to_sun6i_ahb1_clk(_hw) container_of(_hw, struct sun6i_ahb1_clk, hw)
+
+static unsigned long sun6i_ahb1_clk_recalc_rate(struct clk_hw *hw,
+						unsigned long parent_rate)
+{
+	struct sun6i_ahb1_clk *ahb1 = to_sun6i_ahb1_clk(hw);
+	unsigned long rate;
+	u32 reg;
+
+	/* Fetch the register value */
+	reg = readl(ahb1->reg);
+
+	/* apply pre-divider first if parent is pll6 */
+	if (SUN6I_AHB1_MUX_GET_PARENT(reg) == SUN6I_AHB1_MUX_PARENT_PLL6)
+		parent_rate /= SUN6I_AHB1_PLL6_DIV_GET(reg) + 1;
+
+	/* clk divider */
+	rate = parent_rate >> SUN6I_AHB1_DIV_GET(reg);
+
+	return rate;
+}
+
+static long sun6i_ahb1_clk_round(unsigned long rate, u8 *divp, u8 *pre_divp,
+				 u8 parent, unsigned long parent_rate)
+{
+	u8 div, calcp, calcm = 1;
+
+	/*
+	 * clock can only divide, so we will never be able to achieve
+	 * frequencies higher than the parent frequency
+	 */
+	if (parent_rate && rate > parent_rate)
+		rate = parent_rate;
+
+	div = DIV_ROUND_UP(parent_rate, rate);
+
+	/* calculate pre-divider if parent is pll6 */
+	if (parent == SUN6I_AHB1_MUX_PARENT_PLL6) {
+		if (div < 4)
+			calcp = 0;
+		else if (div / 2 < 4)
+			calcp = 1;
+		else if (div / 4 < 4)
+			calcp = 2;
+		else
+			calcp = 3;
+
+		calcm = DIV_ROUND_UP(div, 1 << calcp);
+	} else {
+		calcp = __roundup_pow_of_two(div);
+		calcp = calcp > 3 ? 3 : calcp;
+	}
+
+	/* we were asked to pass back divider values */
+	if (divp) {
+		*divp = calcp;
+		*pre_divp = calcm - 1;
+	}
+
+	return (parent_rate / calcm) >> calcp;
+}
+
+static long sun6i_ahb1_clk_determine_rate(struct clk_hw *hw, unsigned long rate,
+					  unsigned long *best_parent_rate,
+					  struct clk **best_parent_clk)
+{
+	struct clk *clk = hw->clk, *parent, *best_parent = NULL;
+	int i, num_parents;
+	unsigned long parent_rate, best = 0, child_rate, best_child_rate = 0;
+
+	/* find the parent that can help provide the fastest rate <= rate */
+	num_parents = __clk_get_num_parents(clk);
+	for (i = 0; i < num_parents; i++) {
+		parent = clk_get_parent_by_index(clk, i);
+		if (!parent)
+			continue;
+		if (__clk_get_flags(clk) & CLK_SET_RATE_PARENT)
+			parent_rate = __clk_round_rate(parent, rate);
+		else
+			parent_rate = __clk_get_rate(parent);
+
+		child_rate = sun6i_ahb1_clk_round(rate, NULL, NULL, i,
+						  parent_rate);
+
+		if (child_rate <= rate && child_rate > best_child_rate) {
+			best_parent = parent;
+			best = parent_rate;
+			best_child_rate = child_rate;
+		}
+	}
+
+	if (best_parent)
+		*best_parent_clk = best_parent;
+	*best_parent_rate = best;
+
+	return best_child_rate;
+}
+
+static int sun6i_ahb1_clk_set_rate(struct clk_hw *hw, unsigned long rate,
+				   unsigned long parent_rate)
+{
+	struct sun6i_ahb1_clk *ahb1 = to_sun6i_ahb1_clk(hw);
+	unsigned long flags;
+	u8 div, pre_div, parent;
+	u32 reg;
+
+	spin_lock_irqsave(&clk_lock, flags);
+
+	reg = readl(ahb1->reg);
+
+	/* need to know which parent is used to apply pre-divider */
+	parent = SUN6I_AHB1_MUX_GET_PARENT(reg);
+	sun6i_ahb1_clk_round(rate, &div, &pre_div, parent, parent_rate);
+
+	reg = SUN6I_AHB1_DIV_SET(reg, div);
+	reg = SUN6I_AHB1_PLL6_DIV_SET(reg, pre_div);
+	writel(reg, ahb1->reg);
+
+	spin_unlock_irqrestore(&clk_lock, flags);
+
+	return 0;
+}
+
+static const struct clk_ops sun6i_ahb1_clk_ops = {
+	.determine_rate	= sun6i_ahb1_clk_determine_rate,
+	.recalc_rate	= sun6i_ahb1_clk_recalc_rate,
+	.set_rate	= sun6i_ahb1_clk_set_rate,
+};
+
+static void __init sun6i_ahb1_clk_setup(struct device_node *node)
+{
+	struct clk *clk;
+	struct sun6i_ahb1_clk *ahb1;
+	struct clk_mux *mux;
+	const char *clk_name = node->name;
+	const char *parents[SUN6I_AHB1_MAX_PARENTS];
+	void __iomem *reg;
+	int i = 0;
+
+	reg = of_io_request_and_map(node, 0, of_node_full_name(node));
+
+	/* we have a mux, we will have >1 parents */
+	while (i < SUN6I_AHB1_MAX_PARENTS &&
+	       (parents[i] = of_clk_get_parent_name(node, i)) != NULL)
+		i++;
+
+	of_property_read_string(node, "clock-output-names", &clk_name);
+
+	ahb1 = kzalloc(sizeof(struct sun6i_ahb1_clk), GFP_KERNEL);
+	if (!ahb1)
+		return;
+
+	mux = kzalloc(sizeof(struct clk_mux), GFP_KERNEL);
+	if (!mux) {
+		kfree(ahb1);
+		return;
+	}
+
+	/* set up clock properties */
+	mux->reg = reg;
+	mux->shift = SUN6I_AHB1_MUX_SHIFT;
+	mux->mask = SUN6I_AHB1_MUX_MASK;
+	mux->lock = &clk_lock;
+	ahb1->reg = reg;
+
+	clk = clk_register_composite(NULL, clk_name, parents, i,
+				     &mux->hw, &clk_mux_ops,
+				     &ahb1->hw, &sun6i_ahb1_clk_ops,
+				     NULL, NULL, 0);
+
+	if (!IS_ERR(clk)) {
+		of_clk_add_provider(node, of_clk_src_simple_get, clk);
+		clk_register_clkdev(clk, clk_name, NULL);
+	}
+}
+CLK_OF_DECLARE(sun6i_a31_ahb1, "allwinner,sun6i-a31-ahb1-clk", sun6i_ahb1_clk_setup);
+
 /* Maximum number of parents our clocks have */
 #define SUNXI_MAX_PARENTS	5
 
-- 
2.1.3

[PATCH resend v4 2/3] ARM: dts: sun6i: Unify ahb1 clock nodes

[Chen-Yu Tsai]

The clock driver has unified support for the ahb1 clock.
Unify the clock nodes so it works.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
---
 arch/arm/boot/dts/sun6i-a31.dtsi | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/arch/arm/boot/dts/sun6i-a31.dtsi b/arch/arm/boot/dts/sun6i-a31.dtsi
index f47156b..62d932e 100644
--- a/arch/arm/boot/dts/sun6i-a31.dtsi
+++ b/arch/arm/boot/dts/sun6i-a31.dtsi
@@ -174,19 +174,11 @@
 			clock-output-names = "axi";
 		};
 
-		ahb1_mux: ahb1_mux at 01c20054 {
-			#clock-cells = <0>;
-			compatible = "allwinner,sun6i-a31-ahb1-mux-clk";
-			reg = <0x01c20054 0x4>;
-			clocks = <&osc32k>, <&osc24M>, <&axi>, <&pll6 0>;
-			clock-output-names = "ahb1_mux";
-		};
-
 		ahb1: ahb1 at 01c20054 {
 			#clock-cells = <0>;
-			compatible = "allwinner,sun4i-a10-ahb-clk";
+			compatible = "allwinner,sun6i-a31-ahb1-clk";
 			reg = <0x01c20054 0x4>;
-			clocks = <&ahb1_mux>;
+			clocks = <&osc32k>, <&osc24M>, <&axi>, <&pll6 0>;
 			clock-output-names = "ahb1";
 		};
 
@@ -367,7 +359,7 @@
 			#dma-cells = <1>;
 
 			/* DMA controller requires AHB1 clocked from PLL6 */
-			assigned-clocks = <&ahb1_mux>;
+			assigned-clocks = <&ahb1>;
 			assigned-clock-parents = <&pll6 0>;
 		};
 
-- 
2.1.3

[PATCH resend v4 3/3] ARM: dts: sun8i: Unify ahb1 clock nodes

[Chen-Yu Tsai]

The clock driver has unified support for the ahb1 clock.
Unify the clock nodes so it works.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
---
 arch/arm/boot/dts/sun8i-a23.dtsi | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/arch/arm/boot/dts/sun8i-a23.dtsi b/arch/arm/boot/dts/sun8i-a23.dtsi
index 0746cd1..726b613 100644
--- a/arch/arm/boot/dts/sun8i-a23.dtsi
+++ b/arch/arm/boot/dts/sun8i-a23.dtsi
@@ -140,19 +140,11 @@
 			clock-output-names = "axi";
 		};
 
-		ahb1_mux: ahb1_mux_clk at 01c20054 {
-			#clock-cells = <0>;
-			compatible = "allwinner,sun6i-a31-ahb1-mux-clk";
-			reg = <0x01c20054 0x4>;
-			clocks = <&osc32k>, <&osc24M>, <&axi>, <&pll6>;
-			clock-output-names = "ahb1_mux";
-		};
-
 		ahb1: ahb1_clk at 01c20054 {
 			#clock-cells = <0>;
-			compatible = "allwinner,sun4i-a10-ahb-clk";
+			compatible = "allwinner,sun6i-a31-ahb1-clk";
 			reg = <0x01c20054 0x4>;
-			clocks = <&ahb1_mux>;
+			clocks = <&osc32k>, <&osc24M>, <&axi>, <&pll6>;
 			clock-output-names = "ahb1";
 		};
 
-- 
2.1.3

[PATCH resend v4 0/3] clk: sun6i: Unify AHB1 clock and fix rate calculation

[Maxime Ripard]

On Wed, Nov 26, 2014 at 03:16:51PM +0800, Chen-Yu Tsai wrote:
> Hi everyone,
> 
> This is a resend of v4 of the sun6i AHB1 clock unification series.
> This includes only the 3 patches not yet merged.
> 
> This series unifies the mux and divider parts of the AHB1 clock found
> on sun6i and sun8i, while also adding support for the pre-divider on the
> PLL6 input.
> 
> The rate calculation logic must factor in which parent it is using to
> calculate the rate, to decide whether to use the pre-divider or not.
> This is beyond the original factors clk design in sunxi. To avoid
> feature bloat, this is implemented as a separate composite clk.
> 
> The new clock driver is registered with a separate OF_CLK_DECLARE.
> As it shares its register with the APB1 div clock, thus shares the same
> spinlock, it cannot reside in a separate file.

Queued this for 3.20, thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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