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Message-ID: <8ce4c1d8-e379-4fe0-ae31-ba5bdf4c1e06@kernel.org>
Date: Fri, 5 Apr 2024 22:07:04 +0900
From: Damien Le Moal <dlemoal@...nel.org>
To: Geert Uytterhoeven <geert@...ux-m68k.org>,
Yoshinori Sato <ysato@...rs.sourceforge.jp>
Cc: linux-sh@...r.kernel.org, Niklas Cassel <cassel@...nel.org>,
Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>,
Michael Turquette <mturquette@...libre.com>, Stephen Boyd
<sboyd@...nel.org>, David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
Thomas Gleixner <tglx@...utronix.de>, Bjorn Helgaas <bhelgaas@...gle.com>,
Lorenzo Pieralisi <lpieralisi@...nel.org>,
Krzysztof Wilczyński <kw@...ux.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jirislaby@...nel.org>, Magnus Damm <magnus.damm@...il.com>,
Daniel Lezcano <daniel.lezcano@...aro.org>, Rich Felker <dalias@...c.org>,
John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
Lee Jones <lee@...nel.org>, Helge Deller <deller@....de>,
Heiko Stuebner <heiko.stuebner@...rry.de>, Shawn Guo <shawnguo@...nel.org>,
Sebastian Reichel <sre@...nel.org>, Chris Morgan <macromorgan@...mail.com>,
Linus Walleij <linus.walleij@...aro.org>, Arnd Bergmann <arnd@...db.de>,
David Rientjes <rientjes@...gle.com>, Hyeonggon Yoo <42.hyeyoo@...il.com>,
Vlastimil Babka <vbabka@...e.cz>, Baoquan He <bhe@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>, Guenter Roeck
<linux@...ck-us.net>, Kefeng Wang <wangkefeng.wang@...wei.com>,
Stephen Rothwell <sfr@...b.auug.org.au>,
Javier Martinez Canillas <javierm@...hat.com>, Guo Ren <guoren@...nel.org>,
Azeem Shaikh <azeemshaikh38@...il.com>, Max Filippov <jcmvbkbc@...il.com>,
Jonathan Corbet <corbet@....net>, Jacky Huang <ychuang3@...oton.com>,
Herve Codina <herve.codina@...tlin.com>,
Manikanta Guntupalli <manikanta.guntupalli@....com>,
Anup Patel <apatel@...tanamicro.com>, Biju Das <biju.das.jz@...renesas.com>,
Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
Sam Ravnborg <sam@...nborg.org>, Sergey Shtylyov <s.shtylyov@....ru>,
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, dri-devel@...ts.freedesktop.org,
linux-pci@...r.kernel.org, linux-serial@...r.kernel.org,
linux-fbdev@...r.kernel.org
Subject: Re: [RESEND v7 14/37] clk: Compatible with narrow registers
On 4/5/24 21:56, Geert Uytterhoeven wrote:
> Hi Sato-san,
>
> On Thu, Apr 4, 2024 at 7:15 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 the update!
>
>> --- a/drivers/clk/clk-divider.c
>> +++ b/drivers/clk/clk-divider.c
>> @@ -26,20 +26,38 @@
>> * parent - fixed parent. No clk_set_parent support
>> */
>>
>> -static inline u32 clk_div_readl(struct clk_divider *divider)
>> -{
>> - if (divider->flags & CLK_DIVIDER_BIG_ENDIAN)
>> - return ioread32be(divider->reg);
>> -
>> - return readl(divider->reg);
>> +static inline u32 clk_div_read(struct clk_divider *divider)
>> +{
>> + if (divider->flags & CLK_DIVIDER_REG_8BIT)
>
> When you need curly braces in one branch of an if/else statement,
> please use curly braces in all branches (everywhere).
>
>> + return readb(divider->reg);
>> + else if (divider->flags & CLK_DIVIDER_REG_16BIT) {
And no need for an else after a return...
>> + if (divider->flags & CLK_DIVIDER_BIG_ENDIAN)
>> + return ioread16be(divider->reg);
>> + else
and here.
>> + return readw(divider->reg);
>> + } else {
>> + if (divider->flags & CLK_DIVIDER_BIG_ENDIAN)
>> + return ioread32be(divider->reg);
>> + else
here too.
>> + return readl(divider->reg);
>> + }
>> }
>
>> --- a/drivers/clk/clk-gate.c
>> +++ b/drivers/clk/clk-gate.c
>
>> @@ -137,12 +155,30 @@ struct clk_hw *__clk_hw_register_gate(struct device *dev,
>> struct clk_init_data init = {};
>> int ret = -EINVAL;
>>
>> + /* validate register size option and bit_idx */
>> if (clk_gate_flags & CLK_GATE_HIWORD_MASK) {
>> if (bit_idx > 15) {
>> pr_err("gate bit exceeds LOWORD field\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);
>> + }
>> + }
>> + if ((clk_gate_flags & CLK_GATE_HIWORD_MASK) &&
>
> If you use parentheses around "a & b" here...
>
>> + clk_gate_flags & (CLK_GATE_REG_8BIT | CLK_GATE_REG_16BIT)) {
>
> please add parentheses here, too.
>
>> + pr_err("HIWORD_MASK required 32-bit register\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 4a537260f655..eaa6ff1d0b2e 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;
>
> (from my comments on v6)
> There is no need to increase the size of the flags field for the gate clock.
>
>
>> spinlock_t *lock;
>> };
>>
>
>> @@ -675,13 +681,17 @@ struct clk_div_table {
>> * CLK_DIVIDER_BIG_ENDIAN - By default little endian register accesses are used
>> * for the divider register. Setting this flag makes the register accesses
>> * big endian.
>> + * CLK_DIVIDER_REG_8BIT - by default 32bit register accesses are used for
>> + * the gate register. Setting this flag makes the register accesses 8bit.
>> + * CLK_DIVIDER_REG_16BIT - by default 32bit register accesses are used for
>> + * the gate register. Setting this flag makes the register accesses 16bit.
>> */
>> struct clk_divider {
>> struct clk_hw hw;
>> void __iomem *reg;
>> u8 shift;
>> u8 width;
>> - u8 flags;
>> + u16 flags;
>> const struct clk_div_table *table;
>> spinlock_t *lock;
>> };
>
>> @@ -726,18 +738,18 @@ struct clk_hw *__clk_hw_register_divider(struct device *dev,
>> struct device_node *np, const char *name,
>> const char *parent_name, const struct clk_hw *parent_hw,
>> const struct clk_parent_data *parent_data, unsigned long flags,
>> - void __iomem *reg, u8 shift, u8 width, u8 clk_divider_flags,
>> + void __iomem *reg, u8 shift, u8 width, u32 clk_divider_flags,
>
> "u16 clk_divider_flags", to match clk_divider.flags.
>
>> const struct clk_div_table *table, spinlock_t *lock);
>> struct clk_hw *__devm_clk_hw_register_divider(struct device *dev,
>> struct device_node *np, const char *name,
>> const char *parent_name, const struct clk_hw *parent_hw,
>> const struct clk_parent_data *parent_data, unsigned long flags,
>> - void __iomem *reg, u8 shift, u8 width, u8 clk_divider_flags,
>> + void __iomem *reg, u8 shift, u8 width, u32 clk_divider_flags,
>
> Likewise.
>
>> const struct clk_div_table *table, spinlock_t *lock);
>> struct clk *clk_register_divider_table(struct device *dev, const char *name,
>> const char *parent_name, unsigned long flags,
>> void __iomem *reg, u8 shift, u8 width,
>> - u8 clk_divider_flags, const struct clk_div_table *table,
>> + u32 clk_divider_flags, const struct clk_div_table *table,
>
> Likewise.
>
>> spinlock_t *lock);
>> /**
>> * clk_register_divider - register a divider clock with the clock framework
>
> Gr{oetje,eeting}s,
>
> Geert
>
--
Damien Le Moal
Western Digital Research
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