[PATCH v7 01/13] clk: pwm: Use 64-bit division macros for period and duty cycle

[Guru Das Srinagesh]

Because period and duty cycle are defined in the PWM framework structs
as ints with units of nanoseconds, the maximum time duration that can be
set is limited to ~2.147 seconds. Redefining them as u64 values will
enable larger time durations to be set.

As a first step, prepare drivers to handle the switch to u64 period and
duty_cycle by replacing division operations involving pwm period and duty cycle
with their 64-bit equivalents as appropriate. The actual switch to u64 period
and duty_cycle follows as a separate patch.

Where the dividend is 64-bit but the divisor is 32-bit, use *_ULL
macros:
- DIV_ROUND_UP_ULL
- DIV_ROUND_CLOSEST_ULL
- div_u64

Where the divisor is 64-bit (dividend may be 32-bit or 64-bit), use
DIV64_* macros:
- DIV64_U64_ROUND_CLOSEST
- div64_u64

Cc: Michael Turquette <mturquette@xxxxxxxxxxxx>
Cc: Stephen Boyd <sboyd@xxxxxxxxxx>
Cc: linux-clk@xxxxxxxxxxxxxxx

Signed-off-by: Guru Das Srinagesh <gurus@xxxxxxxxxxxxxx>
---
 drivers/clk/clk-pwm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/clk-pwm.c b/drivers/clk/clk-pwm.c
index 87fe0b0e..7b1f7a0 100644
--- a/drivers/clk/clk-pwm.c
+++ b/drivers/clk/clk-pwm.c
@@ -89,7 +89,7 @@ static int clk_pwm_probe(struct platform_device *pdev)
 	}
 
 	if (of_property_read_u32(node, "clock-frequency", &clk_pwm->fixed_rate))
-		clk_pwm->fixed_rate = NSEC_PER_SEC / pargs.period;
+		clk_pwm->fixed_rate = div64_u64(NSEC_PER_SEC, pargs.period);
 
 	if (pargs.period != NSEC_PER_SEC / clk_pwm->fixed_rate &&
 	    pargs.period != DIV_ROUND_UP(NSEC_PER_SEC, clk_pwm->fixed_rate)) {
-- 
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