From 01993e1dda68d85ff6cf11cab6051bcefa46d2c1 Mon Sep 17 00:00:00 2001 From: Remi Pommarel Date: Sun, 6 Dec 2015 17:22:46 +0100 Subject: [PATCH] clk: bcm2835: add a round up ability to the clock divisor Make bcm2835_clock_choose_div to optionally round up the chosen MASH divisor so that the resulting average rate will not be higher than the requested one. Signed-off-by: Remi Pommarel Reviewed-by: Eric Anholt Signed-off-by: Michael Turquette (cherry picked from commit 9c95b32ca09364e4687b72c4e17b78dc1c420026) --- drivers/clk/bcm/clk-bcm2835.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) --- a/drivers/clk/bcm/clk-bcm2835.c +++ b/drivers/clk/bcm/clk-bcm2835.c @@ -1164,22 +1164,24 @@ static int bcm2835_clock_is_on(struct cl static u32 bcm2835_clock_choose_div(struct clk_hw *hw, unsigned long rate, - unsigned long parent_rate) + unsigned long parent_rate, + bool round_up) { struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw); const struct bcm2835_clock_data *data = clock->data; - u32 unused_frac_mask = GENMASK(CM_DIV_FRAC_BITS - data->frac_bits, 0); + u32 unused_frac_mask = + GENMASK(CM_DIV_FRAC_BITS - data->frac_bits, 0) >> 1; u64 temp = (u64)parent_rate << CM_DIV_FRAC_BITS; + u64 rem; u32 div; - do_div(temp, rate); + rem = do_div(temp, rate); div = temp; - /* Round and mask off the unused bits */ - if (unused_frac_mask != 0) { - div += unused_frac_mask >> 1; - div &= ~unused_frac_mask; - } + /* Round up and mask off the unused bits */ + if (round_up && ((div & unused_frac_mask) != 0 || rem != 0)) + div += unused_frac_mask + 1; + div &= ~unused_frac_mask; /* clamp to min divider of 1 */ div = max_t(u32, div, 1 << CM_DIV_FRAC_BITS); @@ -1219,7 +1221,7 @@ static long bcm2835_clock_round_rate(str unsigned long *parent_rate) { struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw); - u32 div = bcm2835_clock_choose_div(hw, rate, *parent_rate); + u32 div = bcm2835_clock_choose_div(hw, rate, *parent_rate, false); return bcm2835_clock_rate_from_divisor(clock, *parent_rate, div); } @@ -1288,7 +1290,7 @@ static int bcm2835_clock_set_rate(struct struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw); struct bcm2835_cprman *cprman = clock->cprman; const struct bcm2835_clock_data *data = clock->data; - u32 div = bcm2835_clock_choose_div(hw, rate, parent_rate); + u32 div = bcm2835_clock_choose_div(hw, rate, parent_rate, false); cprman_write(cprman, data->div_reg, div);