[PATCH v2 4/7] clk: sunxi: unify sun6i AHB1 clock with proper PLL6 pre-divider
From: Chen-Yu Tsai <hidden>
Date: 2014-09-27 08:49:52
Also in:
linux-devicetree
Subsystem:
arm/allwinner soc clock support, common clk framework, open firmware and flattened device tree bindings, the rest · Maintainers:
Emilio López, Michael Turquette, Stephen Boyd, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Linus Torvalds
Possibly related (same subject, not in this thread)
- 2014-10-06 · Re: [PATCH v2 4/7] clk: sunxi: unify sun6i AHB1 clock with proper PLL6 pre-divider · Chen-Yu Tsai <hidden>
- 2014-10-06 · Re: [PATCH v2 4/7] clk: sunxi: unify sun6i AHB1 clock with proper PLL6 pre-divider · Chen-Yu Tsai <hidden>
- 2014-09-30 · Re: [PATCH v2 4/7] clk: sunxi: unify sun6i AHB1 clock with proper PLL6 pre-divider · Maxime Ripard <hidden>
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 <redacted> --- 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 0d84f4b..e862818 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 9caebff..7151e2c 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"
@@ -1357,3 +1358,211 @@ 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);
--
2.1.1