[PATCH v3 6/6] clk: zynqmp: Add support for clock with CLK_DIVIDER_POWER_OF_TWO flag

Rajan Vaja
2019-12-05T06:37:54Z

From: Tejas Patel <tejas.patel@xilinx.com>

Existing clock divider functions is not checking for
base of divider. So, if any clock divider is power of 2
then clock rate calculation will be wrong.

Add support to calculate divider value for the clocks
with CLK_DIVIDER_POWER_OF_TWO flag.

Signed-off-by: Tejas Patel <tejas.patel@xilinx.com>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Signed-off-by: Rajan Vaja <rajan.vaja@xilinx.com>
---
drivers/clk/zynqmp/divider.c | 36 +++++++++++++++++++++++++++++++-----
1 file changed, 31 insertions(+), 5 deletions(-)

diff --git a/drivers/clk/zynqmp/divider.c b/drivers/clk/zynqmp/divider.c
index e0d49cc..1d5a416 100644
--- a/drivers/clk/zynqmp/divider.c
+++ b/drivers/clk/zynqmp/divider.c
@@ -2,7 +2,7 @@
/*
* Zynq UltraScale+ MPSoC Divider support
*
- * Copyright (C) 2016-2018 Xilinx
+ * Copyright (C) 2016-2019 Xilinx
*
* Adjustable divider clock implementation
*/
@@ -45,9 +45,26 @@ struct zynqmp_clk_divider {
};

static inline int zynqmp_divider_get_val(unsigned long parent_rate,
- unsigned long rate)
+ unsigned long rate, u16 flags)
{
- return DIV_ROUND_CLOSEST(parent_rate, rate);
+ int up, down;
+ unsigned long up_rate, down_rate;
+
+ if (flags & CLK_DIVIDER_POWER_OF_TWO) {
+ up = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
+ down = DIV_ROUND_DOWN_ULL((u64)parent_rate, rate);
+
+ up = __roundup_pow_of_two(up);
+ down = __rounddown_pow_of_two(down);
+
+ up_rate = DIV_ROUND_UP_ULL((u64)parent_rate, up);
+ down_rate = DIV_ROUND_UP_ULL((u64)parent_rate, down);
+
+ return (rate - up_rate) <= (down_rate - rate) ? up : down;
+
+ } else {
+ return DIV_ROUND_CLOSEST(parent_rate, rate);
+ }
}

/**
@@ -79,6 +96,9 @@ static unsigned long zynqmp_clk_divider_recalc_rate(struct clk_hw *hw,
else
value = div >> 16;

+ if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
+ value = 1 << value;
+
if (!value) {
WARN(!(divider->flags & CLK_DIVIDER_ALLOW_ZERO),
"%s: Zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n",
@@ -157,10 +177,13 @@ static long zynqmp_clk_divider_round_rate(struct clk_hw *hw,
else
bestdiv = bestdiv >> 16;

+ if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
+ bestdiv = 1 << bestdiv;
+
return DIV_ROUND_UP_ULL((u64)*prate, bestdiv);
}

- bestdiv = zynqmp_divider_get_val(*prate, rate);
+ bestdiv = zynqmp_divider_get_val(*prate, rate, divider->flags);

/*
* In case of two divisors, compute best divider values and return
@@ -198,7 +221,7 @@ static int zynqmp_clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
int ret;
const struct zynqmp_eemi_ops *eemi_ops = zynqmp_pm_get_eemi_ops();

- value = zynqmp_divider_get_val(parent_rate, rate);
+ value = zynqmp_divider_get_val(parent_rate, rate, divider->flags);
if (div_type == TYPE_DIV1) {
div = value & 0xFFFF;
div |= 0xffff << 16;
@@ -207,6 +230,9 @@ static int zynqmp_clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
div |= value << 16;
}

+ if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
+ div = __ffs(div);
+
ret = eemi_ops->clock_setdivider(clk_id, div);

if (ret)
--
2.7.4