[PATCH 04/13] clk: divider: implement CLK_DIVIDER_ALLOW_ZERO

[Ahmad Fatoum]

We already support CLK_DIVIDER_ONE_BASED and incoming STM32MP13 clock
support can have clock dividers evaluate to zero. Add support for
CLK_DIVIDER_ALLOW_ZERO analogously to Linux.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 drivers/clk/clk-divider.c | 6 ++++++
 include/linux/clk.h       | 1 +
 2 files changed, 7 insertions(+)

diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
index 1eaff1675b24..150b1fe60fd4 100644
--- a/drivers/clk/clk-divider.c
+++ b/drivers/clk/clk-divider.c
@@ -88,6 +88,12 @@ unsigned long divider_recalc_rate(struct clk *clk, unsigned long parent_rate,
 	unsigned int div;
 
 	div = _get_div(table, val, flags, width);
+	if (!div) {
+		WARN(!(flags & CLK_DIVIDER_ALLOW_ZERO),
+			"%s: Zero divisor and CLK_DIVIDER_ALLOW_ZERO not set\n",
+			clk->name);
+		return parent_rate;
+	}
 
 	return DIV_ROUND_UP_ULL((u64)parent_rate, div);
 }
diff --git a/include/linux/clk.h b/include/linux/clk.h
index 9975c1a601c4..269664b0ba63 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -417,6 +417,7 @@ struct clk_divider {
 #define clk_div_mask(width)	((1 << (width)) - 1)
 
 #define CLK_DIVIDER_POWER_OF_TWO	(1 << 1)
+#define CLK_DIVIDER_ALLOW_ZERO		(1 << 2)
 #define CLK_DIVIDER_HIWORD_MASK		(1 << 3)
 #define CLK_DIVIDER_READ_ONLY		(1 << 5)
 
-- 
2.39.2