On Mon, 10 Sep 2018 at 23:48, Cédric Le Goater <c...@kaod.org> wrote:
>
> The AHB clock is used by the FMC/SPI controllers.
>
> Signed-off-by: Cédric Le Goater <c...@kaod.org>
> ---
> arch/arm/include/asm/arch-aspeed/scu_ast2500.h | 2 ++
> include/dt-bindings/clock/ast2500-scu.h | 1 +
> drivers/clk/aspeed/clk_ast2500.c | 12 ++++++++++++
> 3 files changed, 15 insertions(+)
>
> diff --git a/arch/arm/include/asm/arch-aspeed/scu_ast2500.h
> b/arch/arm/include/asm/arch-aspeed/scu_ast2500.h
> index 4988ced7ddcc..6a90ded752ad 100644
> --- a/arch/arm/include/asm/arch-aspeed/scu_ast2500.h
> +++ b/arch/arm/include/asm/arch-aspeed/scu_ast2500.h
> @@ -11,6 +11,8 @@
> #define SCU_HWSTRAP_VGAMEM_MASK (3 <<
> SCU_HWSTRAP_VGAMEM_SHIFT)
> #define SCU_HWSTRAP_MAC1_RGMII (1 << 6)
> #define SCU_HWSTRAP_MAC2_RGMII (1 << 7)
> +#define SCU_HWSTRAP_AXIAHB_DIV_SHIFT 9
> +#define SCU_HWSTRAP_AXIAHB_DIV_MASK (0x7 << SCU_HWSTRAP_AXIAHB_DIV_SHIFT)
> #define SCU_HWSTRAP_DDR4 (1 << 24)
> #define SCU_HWSTRAP_CLKIN_25MHZ (1 << 23)
>
> diff --git a/include/dt-bindings/clock/ast2500-scu.h
> b/include/dt-bindings/clock/ast2500-scu.h
> index 4803abe9f628..03e6d16d3de0 100644
> --- a/include/dt-bindings/clock/ast2500-scu.h
> +++ b/include/dt-bindings/clock/ast2500-scu.h
> @@ -17,6 +17,7 @@
> #define BCLK_MACCLK 103
> #define BCLK_SDCLK 104
> #define BCLK_ARMCLK 105
> +#define BCLK_HCLK 106
I like how the clocks are grouped in this file. Are we confident that
HCLK is going in the correct spot?
> #define MCLK_DDR 201
>
> diff --git a/drivers/clk/aspeed/clk_ast2500.c
> b/drivers/clk/aspeed/clk_ast2500.c
> index 526470051c5d..c55f8d5ae30d 100644
> --- a/drivers/clk/aspeed/clk_ast2500.c
> +++ b/drivers/clk/aspeed/clk_ast2500.c
> @@ -143,6 +143,18 @@ static ulong ast2500_clk_get_rate(struct clk *clk)
> rate = rate / apb_div;
> }
> break;
> + case BCLK_HCLK:
> + {
> + ulong ahb_div = 1 + ((readl(&priv->scu->hwstrap)
> + & SCU_HWSTRAP_AXIAHB_DIV_MASK)
> + >> SCU_HWSTRAP_AXIAHB_DIV_SHIFT);
> + ulong axi_div = 2;
> +
> + rate = ast2500_get_hpll_rate(
> + clkin, readl(&priv->scu->h_pll_param));
> + rate = rate / axi_div / ahb_div;
In the kernel driver I wrote it as:
rate / (axi_div + ahb_div)
I know that the maths works, but do the numbers come out as we expect
when doing integer division?
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