Re: [DO NOT MERGE v8 14/36] clk: Compatible with narrow registers
From: Stephen Boyd
Date: Wed May 29 2024 - 19:15:33 EST
Quoting Yoshinori Sato (2024-05-29 01:01:00)
> 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@xxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/clk/clk-divider.c | 41 +++++++++++++++++++++---------
> drivers/clk/clk-gate.c | 49 ++++++++++++++++++++++++++++++++----
> include/linux/clk-provider.h | 20 ++++++++++++---
> 3 files changed, 89 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
> index a2c2b5203b0a..abafcbbb6578 100644
> --- a/drivers/clk/clk-divider.c
> +++ b/drivers/clk/clk-divider.c
> @@ -26,17 +26,34 @@
> * parent - fixed parent. No clk_set_parent support
> */
>
> -static inline u32 clk_div_readl(struct clk_divider *divider)
> -{
> +static inline u32 clk_div_read(struct clk_divider *divider)
Please don't change the name. The 'l' is for the return type, u32, which
is not changed.
> +{
> + if (divider->flags & CLK_DIVIDER_REG_8BIT)
> + return readb(divider->reg);
> + if (divider->flags & CLK_DIVIDER_REG_16BIT) {
> + if (divider->flags & CLK_DIVIDER_BIG_ENDIAN) {
> + return ioread16be(divider->reg);
> + } else {
> + return readw(divider->reg);
> + }
> + }
> if (divider->flags & CLK_DIVIDER_BIG_ENDIAN)
> return ioread32be(divider->reg);
>
> return readl(divider->reg);
> }
>
> -static inline void clk_div_writel(struct clk_divider *divider, u32 val)
> +static inline void clk_div_write(struct clk_divider *divider, u32 val)
Same comment.
> {
> - if (divider->flags & CLK_DIVIDER_BIG_ENDIAN)
> + if (divider->flags & CLK_DIVIDER_REG_8BIT)
> + writeb(val, divider->reg);
> + else if (divider->flags & CLK_DIVIDER_REG_16BIT) {
> + if (divider->flags & CLK_DIVIDER_BIG_ENDIAN) {
> + iowrite16be(val, divider->reg);
> + } else {
> + writew(val, divider->reg);
> + }
> + } else if (divider->flags & CLK_DIVIDER_BIG_ENDIAN)
> iowrite32be(val, divider->reg);
> else
> writel(val, divider->reg);
> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> index 4a537260f655..25f61bd5b952 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -508,6 +508,10 @@ 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;
> @@ -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)
Please add kunit tests for the gate at least.
>
> extern const struct clk_ops clk_gate_ops;
> struct clk_hw *__clk_hw_register_gate(struct device *dev,
> @@ -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;
> };
> @@ -697,6 +707,8 @@ struct clk_divider {
> #define CLK_DIVIDER_READ_ONLY BIT(5)
> #define CLK_DIVIDER_MAX_AT_ZERO BIT(6)
> #define CLK_DIVIDER_BIG_ENDIAN BIT(7)
> +#define CLK_DIVIDER_REG_8BIT BIT(8)
> +#define CLK_DIVIDER_REG_16BIT BIT(9)
>
> extern const struct clk_ops clk_divider_ops;
> extern const struct clk_ops clk_divider_ro_ops;
> @@ -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, u16 clk_divider_flags,
Let's just make this unsigned long for the flags. We don't need to
specify a strict size like this for the callers.
> 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, u16 clk_divider_flags,
Same here.
> 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,
> + u16 clk_divider_flags, const struct clk_div_table *table,
Same here. Preferably do that in another patch too.