Re: [PATCH 13/16] clk: sunxi-ng: Add N-K-M Factor clock

Chen-Yu Tsai
2016-05-23T14:10:16Z

Hi,

On Mon, May 9, 2016 at 4:01 AM, Maxime Ripard
<maxime.ripard@free-electrons.com> wrote:
> Introduce support for clocks that multiply and divide using two linear
> multipliers and one linear divider.
>
> Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
> ---
> drivers/clk/sunxi-ng/Makefile | 1 +
> drivers/clk/sunxi-ng/ccu_nkm.c | 144 +++++++++++++++++++++++++++++++++++++++++
> drivers/clk/sunxi-ng/ccu_nkm.h | 42 ++++++++++++
> 3 files changed, 187 insertions(+)
> create mode 100644 drivers/clk/sunxi-ng/ccu_nkm.c
> create mode 100644 drivers/clk/sunxi-ng/ccu_nkm.h
>
> diff --git a/drivers/clk/sunxi-ng/Makefile b/drivers/clk/sunxi-ng/Makefile
> index fba64c7f4fcd..2bb8bc22e907 100644
> --- a/drivers/clk/sunxi-ng/Makefile
> +++ b/drivers/clk/sunxi-ng/Makefile
> @@ -8,6 +8,7 @@ obj-y += ccu_m.o
> obj-y += ccu_mp.o
> obj-y += ccu_mux.o
> obj-y += ccu_nk.o
> +obj-y += ccu_nkm.o
> obj-y += ccu_nm.o
> obj-y += ccu_p.o
> obj-y += ccu_phase.o
> diff --git a/drivers/clk/sunxi-ng/ccu_nkm.c b/drivers/clk/sunxi-ng/ccu_nkm.c
> new file mode 100644
> index 000000000000..9019c7f6988c
> --- /dev/null
> +++ b/drivers/clk/sunxi-ng/ccu_nkm.c
> @@ -0,0 +1,144 @@
> +/*
> + * Copyright (C) 2016 Maxime Ripard
> + * Maxime Ripard <maxime.ripard@free-electrons.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation; either version 2 of
> + * the License, or (at your option) any later version.
> + */
> +
> +#include <linux/clk-provider.h>
> +#include <linux/rational.h>
> +
> +#include "ccu_gate.h"
> +#include "ccu_nkm.h"
> +
> +void ccu_nkm_find_best(unsigned long parent, unsigned long rate,
> + unsigned long max_n, unsigned long max_k, unsigned long max_m,
> + unsigned long *n, unsigned long *k, unsigned long *m)

Would it be easier to just pass struct ccu_nkm* here?

> +{
> + unsigned long best_rate = 0;
> + unsigned long best_n = 0, best_k = 0, best_m = 0;
> + unsigned long _n, _k, _m;
> +
> + for (_k = 1; _k <= max_k; _k++) {
> + unsigned long tmp_rate;
> +
> + rational_best_approximation(rate / _k, parent,
> + max_n, max_m, &_n, &_m);
> +
> + tmp_rate = parent * _n * _k / _m;
> +
> + if (tmp_rate > rate)
> + continue;
> +
> + if ((rate - tmp_rate) < (rate - best_rate)) {
> + best_rate = tmp_rate;
> + best_n = _n;
> + best_k = _k;
> + best_m = _m;
> + }
> + }
> +
> + *n = best_n;
> + *k = best_k;
> + *m = best_m;
> +}
> +
> +static void ccu_nkm_disable(struct clk_hw *hw)
> +{
> + struct ccu_nkm *nkm = hw_to_ccu_nkm(hw);
> +
> + return ccu_gate_helper_disable(&nkm->common, nkm->enable);
> +}
> +
> +static int ccu_nkm_enable(struct clk_hw *hw)
> +{
> + struct ccu_nkm *nkm = hw_to_ccu_nkm(hw);
> +
> + return ccu_gate_helper_enable(&nkm->common, nkm->enable);
> +}
> +
> +static int ccu_nkm_is_enabled(struct clk_hw *hw)
> +{
> + struct ccu_nkm *nkm = hw_to_ccu_nkm(hw);
> +
> + return ccu_gate_helper_is_enabled(&nkm->common, nkm->enable);
> +}
> +
> +static unsigned long ccu_nkm_recalc_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + struct ccu_nkm *nkm = hw_to_ccu_nkm(hw);
> + unsigned long n, m, k;
> + u32 reg;
> +
> + reg = readl(nkm->common.base + nkm->common.reg);
> +
> + n = reg >> nkm->n.shift;
> + n &= (1 << nkm->n.width) - 1;
> +
> + k = reg >> nkm->k.shift;
> + k &= (1 << nkm->k.width) - 1;
> +
> + m = reg >> nkm->m.shift;
> + m &= (1 << nkm->m.width) - 1;
> +
> + return parent_rate * (n + 1) * (k + 1) / (m + 1);
> +}
> +
> +static long ccu_nkm_round_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long *parent_rate)
> +{
> + struct ccu_nkm *nkm = hw_to_ccu_nkm(hw);
> + unsigned long n, k, m;
> +
> + ccu_nkm_find_best(*parent_rate, rate, 1 << nkm->n.width,
> + 1 << nkm->k.width, 1 << nkm->m.width,
> + &n, &k, &m);
> +
> + return *parent_rate * n * k / m;
> +}
> +
> +static int ccu_nkm_set_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long parent_rate)
> +{
> + struct ccu_nkm *nkm = hw_to_ccu_nkm(hw);
> + unsigned long n, k, m;
> + unsigned long flags;
> + u32 reg;
> +
> + ccu_nkm_find_best(parent_rate, rate, 1 << nkm->n.width,
> + 1 << nkm->k.width, 1 << nkm->m.width,
> + &n, &k, &m);
> +
> + spin_lock_irqsave(nkm->common.lock, flags);
> +
> + reg = readl(nkm->common.base + nkm->common.reg);
> + reg &= ~GENMASK(nkm->n.width + nkm->n.shift, nkm->n.shift);
> + reg &= ~GENMASK(nkm->k.width + nkm->k.shift, nkm->k.shift);
> + reg &= ~GENMASK(nkm->m.width + nkm->m.shift, nkm->m.shift);

GENMASK(width + shift - 1, shift)

> +
> + reg |= (n - 1) << nkm->m.shift;
> + reg |= (k - 1) << nkm->m.shift;
> + reg |= (m - 1) << nkm->m.shift;
> +
> + writel(reg, nkm->common.base + nkm->common.reg);
> +
> + spin_unlock_irqrestore(nkm->common.lock, flags);
> +
> + ccu_helper_wait_for_lock(&nkm->common, nkm->lock);
> +
> + return 0;
> +}
> +
> +const struct clk_ops ccu_nkm_ops = {
> + .disable = ccu_nkm_disable,
> + .enable = ccu_nkm_enable,
> + .is_enabled = ccu_nkm_is_enabled,
> +
> + .recalc_rate = ccu_nkm_recalc_rate,
> + .round_rate = ccu_nkm_round_rate,
> + .set_rate = ccu_nkm_set_rate,
> +};
> diff --git a/drivers/clk/sunxi-ng/ccu_nkm.h b/drivers/clk/sunxi-ng/ccu_nkm.h
> new file mode 100644
> index 000000000000..1301e9f08305
> --- /dev/null
> +++ b/drivers/clk/sunxi-ng/ccu_nkm.h
> @@ -0,0 +1,42 @@
> +/*
> + * Copyright (c) 2016 Maxime Ripard. All rights reserved.
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that 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.
> + */
> +
> +#ifndef _CCU_NKM_H_
> +#define _CCU_NKM_H_
> +
> +#include <linux/clk-provider.h>
> +
> +#include "ccu_factor.h"
> +#include "ccu_common.h"
> +
> +struct ccu_nkm {
> + u32 enable;
> + u32 lock;
> +
> + struct ccu_factor n;
> + struct ccu_factor k;
> + struct ccu_factor m;
> +
> + struct ccu_common common;
> +};
> +
> +static inline struct ccu_nkm *hw_to_ccu_nkm(struct clk_hw *hw)
> +{
> + struct ccu_common *common = hw_to_ccu_common(hw);
> +
> + return container_of(common, struct ccu_nkm, common);
> +}
> +
> +extern const struct clk_ops ccu_nkm_ops;

No macro? I like the macros as they give the actual driver a more table-like
look.

Regards
ChenYu

> +
> +#endif /* _CCU_NKM_H_ */
> --
> 2.8.2
>