Re: [RFC PATCH v1 1/6] rockchip: rockchip: add new clock-type for the ddrclk

Heiko Stübner
2016-06-03T12:51:49Z

Am Freitag, 3. Juni 2016, 17:55:14 schrieb Lin Huang:
> On new rockchip platform(rk3399 etc), there have dcf controller to
> do ddr frequency scaling, and this controller will implement in
> arm-trust-firmware. We add a special clock-type to handle that.
>
> Signed-off-by: Lin Huang <hl@rock-chips.com>
> ---
> Changes in v1:
> - None
>
> drivers/clk/rockchip/Makefile | 1 +
> drivers/clk/rockchip/clk-ddr.c | 147
> +++++++++++++++++++++++++++++++++++++++++ drivers/clk/rockchip/clk.c |
> 9 +++
> drivers/clk/rockchip/clk.h | 27 ++++++++
> 4 files changed, 184 insertions(+)
> create mode 100644 drivers/clk/rockchip/clk-ddr.c
>
> diff --git a/drivers/clk/rockchip/Makefile b/drivers/clk/rockchip/Makefile
> index f47a2fa..b5f2c8e 100644
> --- a/drivers/clk/rockchip/Makefile
> +++ b/drivers/clk/rockchip/Makefile
> @@ -8,6 +8,7 @@ obj-y += clk-pll.o
> obj-y += clk-cpu.o
> obj-y += clk-inverter.o
> obj-y += clk-mmc-phase.o
> +obj-y += clk-ddr.o
> obj-$(CONFIG_RESET_CONTROLLER) += softrst.o
>
> obj-y += clk-rk3036.o
> diff --git a/drivers/clk/rockchip/clk-ddr.c b/drivers/clk/rockchip/clk-ddr.c
> new file mode 100644
> index 0000000..5b6630d
> --- /dev/null
> +++ b/drivers/clk/rockchip/clk-ddr.c
> @@ -0,0 +1,147 @@
> +/*
> + * Copyright (c) 2016 Rockchip Electronics Co. Ltd.
> + * Author: Lin Huang <hl@rock-chips.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.
> + *
> + * 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.
> + */
> +
> +#include <linux/of.h>
> +#include <linux/slab.h>
> +#include <linux/io.h>
> +#include <linux/clk.h>
> +#include <linux/clk-provider.h>
> +#include "clk.h"
> +
> +struct rockchip_ddrclk {
> + struct clk_hw hw;
> + void __iomem *reg_base;
> + int mux_offset;
> + int mux_shift;
> + int mux_width;
> + int mux_flag;
> + int div_shift;
> + int div_width;
> + int div_flag;
> + spinlock_t *lock;
> +};
> +
> +#define to_rockchip_ddrclk_hw(hw) container_of(hw, struct rockchip_ddrclk,
> hw)
> +#define val_mask(width) ((1 << (width)) - 1)

maybe use GENMASK?

> +
> +static int rockchip_ddrclk_set_rate(struct clk_hw *hw, unsigned long drate,
> + unsigned long prate)
> +{
> + struct rockchip_ddrclk *ddrclk = to_rockchip_ddrclk_hw(hw);
> + unsigned long flags;
> +
> + spin_lock_irqsave(ddrclk->lock, flags);
> +
> + /* TODO: set ddr rate in bl31 */

I expect this interface to be in existence and merged into the main ATF first.

Right now the whole clock-type does nothing more than a simple COMPOSITE with
added CLK_DIVIDER_READ_ONLY | CLK_MUX_READ_ONLY.

Also Mike is propably still working in the so called coordinated rate change
for clocks needing special handling on rate changes, which might provide a
second approach to this.

So please, first of all get the ATF-interface merged and meanwhile if you need
to read the clock-rate, just use a regular composite, with the read-only flags.

> + spin_unlock_irqrestore(ddrclk->lock, flags);
> +
> + return 0;
> +}
> +
> +static unsigned long
> +rockchip_ddrclk_recalc_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + struct rockchip_ddrclk *ddrclk = to_rockchip_ddrclk_hw(hw);
> + int val;
> +
> + val = clk_readl(ddrclk->reg_base +
> + ddrclk->mux_offset) >> ddrclk->div_shift;
> + val &= val_mask(ddrclk->div_width);
> +
> + return DIV_ROUND_UP_ULL((u64)parent_rate, val + 1);

return divider_recalc_rate(...)

Heiko