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SubjectRe: [PATCH 1/3] clk: tegra: refactor 7.1 div calculation
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Good Morning,

Just a heads up.
During compilation with your patches, I get the following warning:

In file included from ./arch/arm/include/asm/div64.h:127:0,
from ./include/linux/kernel.h:174,
from drivers/clk/tegra/div71.c:17:
drivers/clk/tegra/div71.c: In function ‘div71_get’:
./include/asm-generic/div64.h:222:28: warning: comparison of distinct
pointer types lacks a cast
(void)(((typeof((n)) *)0) == ((uint64_t *)0)); \
^
drivers/clk/tegra/div71.c:40:2: note: in expansion of macro ‘do_div’
do_div(divider_ux1, rate);
^~~~~~

Very Respectfully,
Peter Geis


On 07/03/2018 07:35 AM, 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.
>
> Signed-off-by: Peter De-Schrijver <pdeschrijver@nvidia.com>
> Signed-off-by: Aapo Vienamo <avienamo@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 | 51 +++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 60 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 e1f8846..f14e136 100644
> --- a/drivers/clk/tegra/clk.h
> +++ b/drivers/clk/tegra/clk.h
> @@ -811,6 +811,9 @@ 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..27b3846
> --- /dev/null
> +++ b/drivers/clk/tegra/div71.c
> @@ -0,0 +1,51 @@
> +/*
> + * Copyright (c) 2018, NVIDIA CORPORATION. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/kernel.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)
> +{
> + s64 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;
> +
> + divider_ux1 -= mul;
> +
> + if (divider_ux1 > div_mask(width))
> + return div_mask(width);
> +
> + return divider_ux1;
> +}

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