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Message-ID: <5510143A.8090404@ti.com>
Date: Mon, 23 Mar 2015 15:25:14 +0200
From: Tero Kristo <t-kristo@...com>
To: Tony Lindgren <tony@...mide.com>,
Mike Turquette <mturquette@...aro.org>,
Stephen Boyd <sboyd@...eaurora.org>
CC: <linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
Brian Hutchinson <b.hutchman@...il.com>,
Matthijs van Duin <matthijsvanduin@...il.com>
Subject: Re: [PATCH 2/3] clk: ti: Implement FAPLL set_rate for the synthesizer
On 03/23/2015 12:35 AM, Tony Lindgren wrote:
> We can pretty much get any rate out of the FAPLL because of the fractional
> divider. Let's first try just adjusting the post divider, and if that is
> not enough, then reprogram both the fractional divider and the post divider.
>
> Let's also add a define for the fixed SYNTH_PHASE_K instead of using 8.
>
> Cc: Brian Hutchinson <b.hutchman@...il.com>
> Cc: Matthijs van Duin <matthijsvanduin@...il.com>
> Cc: Tero Kristo <t-kristo@...com>
> Signed-off-by: Tony Lindgren <tony@...mide.com>
> ---
> drivers/clk/ti/fapll.c | 134 ++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 132 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/ti/fapll.c b/drivers/clk/ti/fapll.c
> index 3b5e231..4064f7b 100644
> --- a/drivers/clk/ti/fapll.c
> +++ b/drivers/clk/ti/fapll.c
> @@ -12,6 +12,7 @@
> #include <linux/clk-provider.h>
> #include <linux/delay.h>
> #include <linux/err.h>
> +#include <linux/math64.h>
> #include <linux/of.h>
> #include <linux/of_address.h>
> #include <linux/clk/ti.h>
> @@ -47,6 +48,8 @@
> /* Synthesizer frequency register */
> #define SYNTH_LDFREQ BIT(31)
>
> +#define SYNTH_PHASE_K 8
> +#define SYNTH_MAX_INT_DIV 0xf
> #define SYNTH_MAX_DIV_M 0xff
>
> struct fapll_data {
> @@ -204,7 +207,7 @@ static unsigned long ti_fapll_synth_recalc_rate(struct clk_hw *hw,
> /*
> * Synth frequency integer and fractional divider.
> * Note that the phase output K is 8, so the result needs
> - * to be multiplied by 8.
> + * to be multiplied by SYNTH_PHASE_K.
> */
> if (synth->freq) {
> u32 v, synth_int_div, synth_frac_div, synth_div_freq;
> @@ -215,7 +218,7 @@ static unsigned long ti_fapll_synth_recalc_rate(struct clk_hw *hw,
> synth_div_freq = (synth_int_div * 10000000) + synth_frac_div;
> rate *= 10000000;
> do_div(rate, synth_div_freq);
> - rate *= 8;
> + rate *= SYNTH_PHASE_K;
> }
>
> /* Synth post-divider M */
> @@ -224,11 +227,138 @@ static unsigned long ti_fapll_synth_recalc_rate(struct clk_hw *hw,
> return DIV_ROUND_UP_ULL(rate, synth_div_m);
> }
>
> +static unsigned long ti_fapll_synth_get_frac_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + struct fapll_synth *synth = to_synth(hw);
> + unsigned long current_rate, frac_rate;
> + u32 post_div_m;
> +
> + current_rate = ti_fapll_synth_recalc_rate(hw, parent_rate);
> + post_div_m = readl_relaxed(synth->div) & SYNTH_MAX_DIV_M;
> + frac_rate = current_rate * post_div_m;
> +
> + return frac_rate;
> +}
> +
> +static u32 ti_fapll_synth_set_frac_rate(struct fapll_synth *synth,
> + unsigned long rate,
> + unsigned long parent_rate)
> +{
> + u32 post_div_m, synth_int_div, synth_frac_div, v;
> +
> + post_div_m = DIV_ROUND_UP_ULL((u64)parent_rate * SYNTH_PHASE_K, rate);
> + post_div_m = post_div_m / SYNTH_MAX_INT_DIV;
> + if (post_div_m > SYNTH_MAX_DIV_M)
> + return -EINVAL;
> + if (!post_div_m)
> + post_div_m = 1;
> +
> + for (; post_div_m < SYNTH_MAX_DIV_M; post_div_m++) {
> + synth_int_div = DIV_ROUND_UP_ULL((u64)parent_rate *
> + SYNTH_PHASE_K *
> + 10000000,
> + rate * post_div_m);
> + synth_frac_div = synth_int_div % 10000000;
> + synth_int_div /= 10000000;
> +
> + if (synth_int_div <= SYNTH_MAX_INT_DIV)
> + break;
> + }
> +
> + if (synth_int_div > SYNTH_MAX_INT_DIV)
> + return -EINVAL;
> +
> + v = readl_relaxed(synth->freq);
> + v &= ~0x1fffffff;
> + v |= (synth_int_div & SYNTH_MAX_INT_DIV) << 24;
> + v |= (synth_frac_div & 0xffffff);
This code is generating these compile time warnings for me:
CC drivers/clk/ti/fapll.o
drivers/clk/ti/fapll.c: In function ‘ti_fapll_synth_set_rate’:
drivers/clk/ti/fapll.c:394:5: warning: ‘synth_int_div’ may be used
uninitialized in this function [-Wuninitialized]
drivers/clk/ti/fapll.c:373:18: note: ‘synth_int_div’ was declared here
drivers/clk/ti/fapll.c:400:23: warning: ‘synth_frac_div’ may be used
uninitialized in this function [-Wuninitialized]
drivers/clk/ti/fapll.c:373:33: note: ‘synth_frac_div’ was declared here
-Tero
> + v |= SYNTH_LDFREQ;
> + writel_relaxed(v, synth->freq);
> +
> + return post_div_m;
> +}
> +
> +static long ti_fapll_synth_round_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long *parent_rate)
> +{
> + struct fapll_synth *synth = to_synth(hw);
> + struct fapll_data *fd = synth->fd;
> + unsigned long r;
> +
> + if (ti_fapll_clock_is_bypass(fd) || !synth->div || !rate)
> + return -EINVAL;
> +
> + /* Only post divider m available with no fractional divider? */
> + if (!synth->freq) {
> + unsigned long frac_rate;
> + u32 synth_post_div_m;
> +
> + frac_rate = ti_fapll_synth_get_frac_rate(hw, *parent_rate);
> + synth_post_div_m = DIV_ROUND_UP(frac_rate, rate);
> + r = DIV_ROUND_UP(frac_rate, synth_post_div_m);
> + goto out;
> + }
> +
> + r = *parent_rate * SYNTH_PHASE_K;
> + if (rate > r)
> + goto out;
> +
> + r = DIV_ROUND_UP_ULL(r, SYNTH_MAX_INT_DIV * SYNTH_MAX_DIV_M);
> + if (rate < r)
> + goto out;
> +
> + r = rate;
> +out:
> + return r;
> +}
> +
> +static int ti_fapll_synth_set_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long parent_rate)
> +{
> + struct fapll_synth *synth = to_synth(hw);
> + struct fapll_data *fd = synth->fd;
> + unsigned long frac_rate, post_rate = 0;
> + u32 post_div_m = 0, v;
> +
> + if (ti_fapll_clock_is_bypass(fd) || !synth->div || !rate)
> + return -EINVAL;
> +
> + /* Produce the rate with just post divider M? */
> + frac_rate = ti_fapll_synth_get_frac_rate(hw, parent_rate);
> + if (frac_rate < rate) {
> + if (!synth->freq)
> + return -EINVAL;
> + } else {
> + post_div_m = DIV_ROUND_UP(frac_rate, rate);
> + if (post_div_m && (post_div_m <= SYNTH_MAX_DIV_M))
> + post_rate = DIV_ROUND_UP(frac_rate, post_div_m);
> + if (!synth->freq && !post_rate)
> + return -EINVAL;
> + }
> +
> + /* Need to recalculate the fractional divider? */
> + if ((post_rate != rate) && synth->freq)
> + post_div_m = ti_fapll_synth_set_frac_rate(synth,
> + rate,
> + parent_rate);
> +
> + v = readl_relaxed(synth->div);
> + v &= ~SYNTH_MAX_DIV_M;
> + v |= post_div_m;
> + v |= SYNTH_LDMDIV1;
> + writel_relaxed(v, synth->div);
> +
> + return 0;
> +}
> +
> static struct clk_ops ti_fapll_synt_ops = {
> .enable = ti_fapll_synth_enable,
> .disable = ti_fapll_synth_disable,
> .is_enabled = ti_fapll_synth_is_enabled,
> .recalc_rate = ti_fapll_synth_recalc_rate,
> + .round_rate = ti_fapll_synth_round_rate,
> + .set_rate = ti_fapll_synth_set_rate,
> };
>
> static struct clk * __init ti_fapll_synth_setup(struct fapll_data *fd,
>
--
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