lkml.org 
[lkml]   [2018]   [Jul]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v4 2/4] clk: tegra: refactor 7.1 div calculation
On Tue, Jul 10, 2018 at 05:17:05PM +0100, Jon Hunter wrote:
>
> On 09/07/18 17:38, Aapo Vienamo wrote:
> > From: Peter De Schrijver <pdeschrijver@nvidia.com>
> >
> > Move this to a separate file so it can be used to calculate the sdmmc
> > clock dividers.
>
> Sorry for not commenting sooner, but what is the motivation for moving
> this to its own file? I don't see why we need to do this in order to use
> elsewhere. Furthermore, the original file is quite aptly named 'clk-divider.c'
> and now we have a div71.c which seems quite specific.

How else would you do it?

Peter.

> > Signed-off-by: Peter De-Schrijver <pdeschrijver@nvidia.com>
> > Signed-off-by: Aapo Vienamo <avienamo@nvidia.com>
> > Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com>
> > ---
> > drivers/clk/tegra/Makefile | 1 +
> > drivers/clk/tegra/clk-divider.c | 30 +++++-----------------------
> > drivers/clk/tegra/clk.h | 3 +++
> > drivers/clk/tegra/div71.c | 43 +++++++++++++++++++++++++++++++++++++++++
> > 4 files changed, 52 insertions(+), 25 deletions(-)
> > create mode 100644 drivers/clk/tegra/div71.c
> >
> > diff --git a/drivers/clk/tegra/Makefile b/drivers/clk/tegra/Makefile
> > index b716923..6d4f563 100644
> > --- a/drivers/clk/tegra/Makefile
> > +++ b/drivers/clk/tegra/Makefile
> > @@ -24,3 +24,4 @@ obj-$(CONFIG_ARCH_TEGRA_132_SOC) += clk-tegra124.o
> > obj-y += cvb.o
> > obj-$(CONFIG_ARCH_TEGRA_210_SOC) += clk-tegra210.o
> > obj-$(CONFIG_CLK_TEGRA_BPMP) += clk-bpmp.o
> > +obj-y += div71.o
> > diff --git a/drivers/clk/tegra/clk-divider.c b/drivers/clk/tegra/clk-divider.c
> > index 16e0aee..ad87858 100644
> > --- a/drivers/clk/tegra/clk-divider.c
> > +++ b/drivers/clk/tegra/clk-divider.c
> > @@ -32,35 +32,15 @@
> > static int get_div(struct tegra_clk_frac_div *divider, unsigned long rate,
> > unsigned long parent_rate)
> > {
> > - u64 divider_ux1 = parent_rate;
> > - u8 flags = divider->flags;
> > - int mul;
> > -
> > - if (!rate)
> > - return 0;
> > -
> > - mul = get_mul(divider);
> > -
> > - if (!(flags & TEGRA_DIVIDER_INT))
> > - divider_ux1 *= mul;
> > -
> > - if (flags & TEGRA_DIVIDER_ROUND_UP)
> > - divider_ux1 += rate - 1;
> > -
> > - do_div(divider_ux1, rate);
> > -
> > - if (flags & TEGRA_DIVIDER_INT)
> > - divider_ux1 *= mul;
> > + int div;
> >
> > - divider_ux1 -= mul;
> > + div = div71_get(rate, parent_rate, divider->width, divider->frac_width,
> > + divider->flags);
> >
> > - if ((s64)divider_ux1 < 0)
> > + if (div < 0)
> > return 0;
> >
> > - if (divider_ux1 > get_max_div(divider))
> > - return get_max_div(divider);
> > -
> > - return divider_ux1;
> > + return div;
> > }
> >
> > static unsigned long clk_frac_div_recalc_rate(struct clk_hw *hw,
> > diff --git a/drivers/clk/tegra/clk.h b/drivers/clk/tegra/clk.h
> > index e3b9c22..149cc70 100644
> > --- a/drivers/clk/tegra/clk.h
> > +++ b/drivers/clk/tegra/clk.h
> > @@ -812,6 +812,9 @@ extern tegra_clk_apply_init_table_func tegra_clk_apply_init_table;
> > int tegra_pll_wait_for_lock(struct tegra_clk_pll *pll);
> > u16 tegra_pll_get_fixed_mdiv(struct clk_hw *hw, unsigned long input_rate);
> > int tegra_pll_p_div_to_hw(struct tegra_clk_pll *pll, u8 p_div);
> > +int div71_get(unsigned long rate, unsigned parent_rate, u8 width,
> > + u8 frac_width, u8 flags);
> > +
> >
> > /* Combined read fence with delay */
> > #define fence_udelay(delay, reg) \
> > diff --git a/drivers/clk/tegra/div71.c b/drivers/clk/tegra/div71.c
> > new file mode 100644
> > index 0000000..1eecc84
> > --- /dev/null
> > +++ b/drivers/clk/tegra/div71.c
> > @@ -0,0 +1,43 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (c) 2018, NVIDIA CORPORATION. All rights reserved.
> > + */
> > +
> > +#include <asm/div64.h>
> > +
> > +#include "clk.h"
> > +
> > +#define div_mask(w) ((1 << (w)) - 1)
> > +
> > +int div71_get(unsigned long rate, unsigned parent_rate, u8 width,
> > + u8 frac_width, u8 flags)
> > +{
> > + u64 divider_ux1 = parent_rate;
> > + int mul;
> > +
> > + if (!rate)
> > + return 0;
> > +
> > + mul = 1 << frac_width;
> > +
> > + if (!(flags & TEGRA_DIVIDER_INT))
> > + divider_ux1 *= mul;
> > +
> > + if (flags & TEGRA_DIVIDER_ROUND_UP)
> > + divider_ux1 += rate - 1;
> > +
> > + do_div(divider_ux1, rate);
> > +
> > + if (flags & TEGRA_DIVIDER_INT)
> > + divider_ux1 *= mul;
> > +
> > + if (divider_ux1 < mul)
> > + return 0;
> > +
> > + divider_ux1 -= mul;
> > +
> > + if (divider_ux1 > div_mask(width))
> > + return div_mask(width);
> > +
> > + return divider_ux1;
> > +}
>
> I don't see anything in the above that makes this 7.1? It seems that the
> fractional width is being passed meaning it could be m.n unless I am missing
> something.
>
> Cheers
> Jon
>
> --
> nvpublic
> --
> To unsubscribe from this list: send the line "unsubscribe linux-clk" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html

\
 
 \ /
  Last update: 2018-07-11 10:01    [W:0.040 / U:2.776 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site