[PATCH 3/7] clk: sunxi: unify sun6i AHB1 clock with proper PLL6 pre-divider

Chen-Yu Tsai
2014-09-06T10:47:24Z

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 | 209 ++++++++++++++++++++++
2 files changed, 210 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/clock/sunxi.txt b/Documentation/devicetree/bindings/clock/sunxi.txt
index d3a5c3c..3d531d6 100644
--- a/Documentation/devicetree/bindings/clock/sunxi.txt
+++ b/Documentation/devicetree/bindings/clock/sunxi.txt
@@ -23,7 +23,7 @@ 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,sun4i-a10-apb0-clk" - for the APB0 clock
diff --git a/drivers/clk/sunxi/clk-sunxi.c b/drivers/clk/sunxi/clk-sunxi.c
index be9ac07..87b7740 100644
--- a/drivers/clk/sunxi/clk-sunxi.c
+++ b/drivers/clk/sunxi/clk-sunxi.c
@@ -19,6 +19,7 @@
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/reset-controller.h>
+#include <linux/log2.h>

#include "clk-factors.h"

@@ -1339,3 +1340,211 @@ static void __init sun6i_init_clocks(struct device_node *node)
}
CLK_OF_DECLARE(sun6i_a31_clk_init, "allwinner,sun6i-a31", sun6i_init_clocks);
CLK_OF_DECLARE(sun8i_a23_clk_init, "allwinner,sun8i-a23", sun6i_init_clocks);
+
+
+/**
+ * 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
+#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
+#define SUN6I_AHB1_DIV_GET(reg) ((reg >> SUN6I_AHB1_DIV_SHIFT) & \
+ SUN6I_AHB1_DIV_MASK)
+#define SUN6I_AHB1_DIV_SET(reg, div) ((reg & ~(SUN6I_AHB1_DIV_MASK << \
+ SUN6I_AHB1_DIV_SHIFT)) | \
+ (div << SUN6I_AHB1_DIV_SHIFT))
+#define SUN6I_AHB1_PLL6_DIV_SHIFT 6
+#define SUN6I_AHB1_PLL6_DIV_MASK 0x3
+#define SUN6I_AHB1_PLL6_DIV_GET(reg) ((reg >> SUN6I_AHB1_PLL6_DIV_SHIFT) & \
+ SUN6I_AHB1_PLL6_DIV_MASK)
+#define SUN6I_AHB1_PLL6_DIV_SET(reg, div) ((reg & \
+ ~(SUN6I_AHB1_PLL6_DIV_MASK << \
+ SUN6I_AHB1_PLL6_DIV_SHIFT)) | \
+ (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;
+ }
+
+ 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_iomap(node, 0);
+
+ /* 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);
--
2.1.0