[U-Boot] [PATCH] arm: mvebu: set 38x and 39x AVS on lower frequency

[Chris Packham]

On Tue, Jun 25, 2019 at 5:50 PM Baruch Siach <baruch at tkos.co.il> wrote:
>
> Hi Chris,
>
> On Tue, Jun 25 2019, Chris Packham wrote:
> > On Mon, Jun 24, 2019 at 8:30 PM Baruch Siach <baruch at tkos.co.il> wrote:
> >>
> >> Reduce Auto Voltage Scaling VDD limit when core frequency is lower than
> >> 1600MHz. This reduces core voltage level from 1.25V to 1.15V, which
> >> saves power.
> >>
> >> The code is taken from Marvell's U-Boot 2013.01 revision 18.06.
> >>
> >> Signed-off-by: Baruch Siach <baruch at tkos.co.il>
> >
> > I gave it a quick spin on DB-88F6820-AMC and x530. Both booted fine.
>
> Is there AVS feedback circuit on these boards? If so, have you measured
> how this patch affects core voltage?
>

Both boards have circuitry for AVS_FB although the x530 strapping will
probably mean that this code skips it. I'll see if I can measure and
difference in behaviour tomorrow.

> > Reviewed-by: Chris Packham <judge.packham at gmail.com>
> > Tested-by: Chris Packham <judge.packham at gmail.com>
>
> Thanks,
> baruch
>
> >> ---
> >>  arch/arm/mach-mvebu/include/mach/cpu.h        |  3 +++
> >>  arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c | 26 +++++++++++++++++++
> >>  arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h |  4 +++
> >>  arch/arm/mach-mvebu/spl.c                     |  3 +++
> >>  4 files changed, 36 insertions(+)
> >>
> >> diff --git a/arch/arm/mach-mvebu/include/mach/cpu.h b/arch/arm/mach-mvebu/include/mach/cpu.h
> >> index e6140d67293e..e1128ee90f01 100644
> >> --- a/arch/arm/mach-mvebu/include/mach/cpu.h
> >> +++ b/arch/arm/mach-mvebu/include/mach/cpu.h
> >> @@ -163,6 +163,9 @@ int serdes_phy_config(void);
> >>   */
> >>  int ddr3_init(void);
> >>
> >> +/* Auto Voltage Scaling */
> >> +void mv_avs_init(void);
> >> +
> >>  /*
> >>   * get_ref_clk
> >>   *
> >> diff --git a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c
> >> index d387893af37d..e9dd096ad0f5 100644
> >> --- a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c
> >> +++ b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c
> >> @@ -256,3 +256,29 @@ u8 sys_env_device_rev_get(void)
> >>         value = reg_read(DEV_VERSION_ID_REG);
> >>         return (value & (REVISON_ID_MASK)) >> REVISON_ID_OFFS;
> >>  }
> >> +
> >> +void mv_avs_init(void)
> >> +{
> >> +       u32 sar_freq;
> >> +
> >> +       if (!(IS_ENABLED(CONFIG_ARMADA_38X) || IS_ENABLED(CONFIG_ARMADA_39X)))
> >> +               return;
> >> +
> >> +       reg_write(AVS_DEBUG_CNTR_REG, AVS_DEBUG_CNTR_DEFAULT_VALUE);
> >> +       reg_write(AVS_DEBUG_CNTR_REG, AVS_DEBUG_CNTR_DEFAULT_VALUE);
> >> +
> >> +       sar_freq = reg_read(DEVICE_SAMPLE_AT_RESET1_REG);
> >> +       sar_freq = sar_freq >> SAR_FREQ_OFFSET & SAR_FREQ_MASK;
> >> +
> >> +       /* Set AVS value only for core frequency of 1600MHz or less.
> >> +        * For higher frequency leave the default value.
> >> +        */
> >> +       if (sar_freq <= 0xd) {
> >> +               u32 avs_reg_data = reg_read(AVS_ENABLED_CONTROL);
> >> +
> >> +               avs_reg_data &= ~(AVS_LOW_VDD_LIMIT_MASK
> >> +                               | AVS_HIGH_VDD_LIMIT_MASK);
> >> +               avs_reg_data |= AVS_LOW_VDD_SLOW_VAL | AVS_HIGH_VDD_SLOW_VAL;
> >> +               reg_write(AVS_ENABLED_CONTROL, avs_reg_data);
> >> +       }
> >> +}
> >> diff --git a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h
> >> index 365332d2b048..1774a5b780ca 100644
> >> --- a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h
> >> +++ b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h
> >> @@ -33,6 +33,8 @@
> >>  #define DEV_ID_REG_DEVICE_ID_OFFS      16
> >>  #define DEV_ID_REG_DEVICE_ID_MASK      0xffff0000
> >>
> >> +#define SAR_FREQ_OFFSET                        10
> >> +#define SAR_FREQ_MASK                  0x1f
> >>  #define SAR_DEV_ID_OFFS                        27
> >>  #define SAR_DEV_ID_MASK                        0x7
> >>
> >> @@ -155,10 +157,12 @@
> >>  #define AVS_LOW_VDD_LIMIT_OFFS         4
> >>  #define AVS_LOW_VDD_LIMIT_MASK         (0xff << AVS_LOW_VDD_LIMIT_OFFS)
> >>  #define AVS_LOW_VDD_LIMIT_VAL          (0x27 << AVS_LOW_VDD_LIMIT_OFFS)
> >> +#define AVS_LOW_VDD_SLOW_VAL           (0x23 << AVS_LOW_VDD_LIMIT_OFFS)
> >>
> >>  #define AVS_HIGH_VDD_LIMIT_OFFS                12
> >>  #define AVS_HIGH_VDD_LIMIT_MASK                (0xff << AVS_HIGH_VDD_LIMIT_OFFS)
> >>  #define AVS_HIGH_VDD_LIMIT_VAL         (0x27 << AVS_HIGH_VDD_LIMIT_OFFS)
> >> +#define AVS_HIGH_VDD_SLOW_VAL          (0x23 << AVS_HIGH_VDD_LIMIT_OFFS)
> >>
> >>  /* Board ID numbers */
> >>  #define MARVELL_BOARD_ID_MASK          0x10
> >> diff --git a/arch/arm/mach-mvebu/spl.c b/arch/arm/mach-mvebu/spl.c
> >> index d54de5195624..3cb27b7f4b20 100644
> >> --- a/arch/arm/mach-mvebu/spl.c
> >> +++ b/arch/arm/mach-mvebu/spl.c
> >> @@ -126,6 +126,9 @@ void board_init_f(ulong dummy)
> >>         ddr3_init();
> >>  #endif
> >>
> >> +       /* Initialize Auto Voltage Scaling */
> >> +       mv_avs_init();
> >> +
> >>         /*
> >>          * Return to the BootROM to continue the Marvell xmodem
> >>          * UART boot protocol. As initiated by the kwboot tool.
>
> --
>      http://baruch.siach.name/blog/                  ~. .~   Tk Open Systems
> =}------------------------------------------------ooO--U--Ooo------------{=
>    - baruch at tkos.co.il - tel: +972.52.368.4656, http://www.tkos.co.il -