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Message-ID: <CAMuHMdVxWrrKT8H_47EPjZ61QnEvvtrZYXFo=FmozhVeYf=4Bw@mail.gmail.com>
Date: Tue, 27 Feb 2024 16:41:53 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Yoshinori Sato <ysato@...rs.sourceforge.jp>
Cc: linux-sh@...r.kernel.org, Damien Le Moal <dlemoal@...nel.org>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>,
Geert Uytterhoeven <geert+renesas@...der.be>, Michael Turquette <mturquette@...libre.com>,
Stephen Boyd <sboyd@...nel.org>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
Thomas Gleixner <tglx@...utronix.de>, Lorenzo Pieralisi <lpieralisi@...nel.org>,
Krzysztof Wilczyński <kw@...ux.com>,
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Palmer Dabbelt <palmer@...osinc.com>, Bin Meng <bmeng@...ylab.org>,
Jonathan Corbet <corbet@....net>, Jacky Huang <ychuang3@...oton.com>,
Lukas Bulwahn <lukas.bulwahn@...il.com>, Biju Das <biju.das.jz@...renesas.com>,
Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
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Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>, linux-ide@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-renesas-soc@...r.kernel.org, linux-clk@...r.kernel.org,
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Subject: Re: [DO NOT MERGE v6 14/37] clk: Compatible with narrow registers
Hi Sato-san,
On Tue, Jan 9, 2024 at 9:24 AM Yoshinori Sato
<ysato@...rs.sourceforge.jp> wrote:
> divider and gate only support 32-bit registers.
> Older hardware uses narrower registers, so I want to be able to handle
> 8-bit and 16-bit wide registers.
>
> Seven clk_divider flags are used, and if I add flags for 8bit access and
> 16bit access, 8bit will not be enough, so I expanded it to u16.
>
> Signed-off-by: Yoshinori Sato <ysato@...rs.sourceforge.jp>
Thanks for your patch!
> --- a/drivers/clk/clk-gate.c
> +++ b/drivers/clk/clk-gate.c
> @@ -143,6 +161,18 @@ struct clk_hw *__clk_hw_register_gate(struct device *dev,
> return ERR_PTR(-EINVAL);
> }
Please add a check for invalid CLK_GATE_HIWORD_MASK
and register width combinations:
if (clk_gate_flags & (CLK_GATE_REG_16BIT | CLK_GATE_REG_8BIT)) {
pr_err("HIWORD_MASK needs 32-bit registers\n");
return ERR_PTR(-EINVAL);
}
> }
> + if (clk_gate_flags & CLK_GATE_REG_16BIT) {
> + if (bit_idx > 15) {
> + pr_err("gate bit exceeds 16 bits\n");
> + return ERR_PTR(-EINVAL);
> + }
> + }
> + if (clk_gate_flags & CLK_GATE_REG_8BIT) {
> + if (bit_idx > 7) {
> + pr_err("gate bit exceeds 8 bits\n");
> + return ERR_PTR(-EINVAL);
> + }
> + }
>
> /* allocate the gate */
> gate = kzalloc(sizeof(*gate), GFP_KERNEL);
> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> index ace3a4ce2fc9..e2dfc1f083f4 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -508,12 +508,16 @@ void of_fixed_clk_setup(struct device_node *np);
> * CLK_GATE_BIG_ENDIAN - by default little endian register accesses are used for
> * the gate register. Setting this flag makes the register accesses big
> * endian.
> + * CLK_GATE_REG_8BIT - by default 32bit register accesses are used for
> + * the gate register. Setting this flag makes the register accesses 8bit.
> + * CLK_GATE_REG_16BIT - by default 32bit register accesses are used for
> + * the gate register. Setting this flag makes the register accesses 16bit.
> */
> struct clk_gate {
> struct clk_hw hw;
> void __iomem *reg;
> u8 bit_idx;
> - u8 flags;
> + u32 flags;
There is no need to increase the size of the flags field for the gate clock.
> spinlock_t *lock;
> };
>
> @@ -522,6 +526,8 @@ struct clk_gate {
> #define CLK_GATE_SET_TO_DISABLE BIT(0)
> #define CLK_GATE_HIWORD_MASK BIT(1)
> #define CLK_GATE_BIG_ENDIAN BIT(2)
> +#define CLK_GATE_REG_8BIT BIT(3)
> +#define CLK_GATE_REG_16BIT BIT(4)
>
> extern const struct clk_ops clk_gate_ops;
> struct clk_hw *__clk_hw_register_gate(struct device *dev,
The rest LGTM.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68korg
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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