On 09/11/2018 06:42 PM, Maxim Sloyko wrote: > > > On Tue, Sep 11, 2018 at 12:35 AM, Joel Stanley <j...@jms.id.au > <mailto:j...@jms.id.au>> wrote: > > On Mon, 10 Sep 2018 at 23:48, Cédric Le Goater <c...@kaod.org > <mailto:c...@kaod.org>> wrote: > > > > The AHB clock is used by the FMC/SPI controllers. > > > > Signed-off-by: Cédric Le Goater <c...@kaod.org <mailto: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) > > > These are two different formulae -- just want to make sure that the typo only > made it into an email :) > > In any case, the exact right way to do this computation depends on how this > is implemented in the hardware itself. Most likely it's to dividers in > sequence, so dividing twice should be more accurate. Of course it would be > nice if somebody with hw design experience could comment. > > If the datasheet has formula, I think the right way is to use it exactly as > stated.
it's two dividers in sequence in the datasheet. In the SDK also. > > > I know that the maths works, but do the numbers come out as we expect > when doing integer division? Yes. 192MHz. Thanks, C. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
