Hello Mike, Vijayakumar,
one comment below.
On Tue, 9 Feb 2010, G.N, Vijayakumar wrote:
> From: Mike Turquette <mturquette@xxxxxx>
> Date: Fri, 5 Feb 2010 19:09:52 +0530
> Subject: [PATCH] OMAP3630: Clock: Workaround for DPLL HS divider limitation
>
> This patch implements a workaround for the DPLL HS divider limitation
> in OMAP3630 as given by Errata ID: i556.
>
> Errata:
> When PWRDN bit is set, it resets the internal HSDIVIDER divide-by value (Mx).
> The reset value gets loaded instead of the previous value.
> The following HSDIVIDERs exhibit above behavior:
> . DPLL4 : M6 / M5 / M4 / M3 / M2 (CM_CLKEN_PLL[31:26] register bits)
> . DPLL3 : M3 (CM_CLKEN_PLL[12] register bit).
>
> Work Around:
> It is mandatory to apply the following sequence to ensure the write
> value will
> be loaded in DPLL HSDIVIDER FSM:
> The global sequence when using PWRDN bit is the following:
> . Disable Mx HSDIVIDER clock output related functional clock enable bits
> (in CM_FCLKEN_xxx / CM_ICLKEN_xxx)
> . Enable PWRDN bit of HSDIVIDER
> . Disable PWRDN bit of HSDIVIDER
> . Read current HSDIVIDER register value
> . Write different value in HSDIVIDER register
> . Write expected value in HSDIVIDER register
> . Enable Mx HSDIVIDER clock output related functional clocks
> (CM_FCLKEN_xxx / CM_ICLKEN_xxx)
>
> Signed-off-by: Mike Turquette <mturquette@xxxxxx>
> Signed-off-by: Vishwanath BS <vishwanath.bs@xxxxxx>
> Signed-off-by: Vijaykumar GN <vijaykumar.gn@xxxxxx>
> ---
> arch/arm/mach-omap2/clock34xx.c | 41 ++++++++++++++++++++++++++++++++++
> arch/arm/mach-omap2/clock34xx.h | 1 +
> arch/arm/mach-omap2/clock34xx_data.c | 20 ++++++++++++++++
> 3 files changed, 62 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/clock34xx.c b/arch/arm/mach-omap2/clock34xx.c
> index c1c1b93..1e6297f 100644
> --- a/arch/arm/mach-omap2/clock34xx.c
> +++ b/arch/arm/mach-omap2/clock34xx.c
> @@ -133,6 +133,47 @@ const struct clkops clkops_omap3430es2_hsotgusb_wait = {
> .find_companion = omap2_clk_dflt_find_companion,
> };
>
> +/**
> + * omap3_pwrdn_clk_enable_with_hsdiv_restore - enable clocks suffering
> + * from HSDivider PWRDN problem Implements Errata ID: i556.
> + * @clk: DPLL output struct clk
> + *
> + * 3630 only: dpll3_m3_ck, dpll4_m2_ck, dpll4_m3_ck, dpll4_m4_ck, dpll4_m5_ck
> + * & dpll4_m6_ck dividers gets loaded with reset valueafter their respective
> + * PWRDN bits are set.
> + * Any dummy write (Any other value different from the Read value) to the
> + * corresponding CM_CLKSEL register will refresh the dividers.
> + */
> +int omap3_pwrdn_clk_enable_with_hsdiv_restore(struct clk *clk)
> +{
> + u32 dummy_v, orig_v, clksel_shift;
> + int ret;
> +
> + /* Enable PWRDN bit of HSDIVIDER */
> + ret = omap2_dflt_clk_enable(clk);
> +
> + /* Restore the dividers */
> + if (!ret) {
> + clksel_shift = __ffs(clk->parent->clksel_mask);
> + orig_v = dummy_v = __raw_readl(clk->parent->clksel_reg);
> +
> + /* Write any other value different from the Read value */
> + dummy_v ^= (1 << clksel_shift);
Shouldn't there also be a:
dummy_v &= clk->parent->clksel_mask;
here to avoid writing to reserved bits?
> + __raw_writel(dummy_v, clk->parent->clksel_reg);
> +
> + /* Write the original divider */
> + __raw_writel(orig_v, clk->parent->clksel_reg);
> + }
> + return ret;
> +}
> +
> +const struct clkops clkops_omap3_pwrdn_with_hsdiv_wait_restore = {
> + .enable = omap3_pwrdn_clk_enable_with_hsdiv_restore,
> + .disable = omap2_dflt_clk_disable,
> + .find_companion = omap2_clk_dflt_find_companion,
> + .find_idlest = omap2_clk_dflt_find_idlest,
> +};
> +
> const struct clkops omap3_clkops_noncore_dpll_ops = {
> .enable = omap3_noncore_dpll_enable,
> .disable = omap3_noncore_dpll_disable,
> diff --git a/arch/arm/mach-omap2/clock34xx.h b/arch/arm/mach-omap2/clock34xx.h
> index 313efc0..29ef390 100644
> --- a/arch/arm/mach-omap2/clock34xx.h
> +++ b/arch/arm/mach-omap2/clock34xx.h
> @@ -21,5 +21,6 @@ extern const struct clkops clkops_omap3430es2_ssi_wait;
> extern const struct clkops clkops_omap3430es2_hsotgusb_wait;
> extern const struct clkops clkops_omap3430es2_dss_usbhost_wait;
> extern const struct clkops omap3_clkops_noncore_dpll_ops;
> +extern const struct clkops clkops_omap3_pwrdn_with_hsdiv_wait_restore;
>
> #endif
> diff --git a/arch/arm/mach-omap2/clock34xx_data.c b/arch/arm/mach-omap2/clock34xx_data.c
> index 8728f1f..9d11d53 100644
> --- a/arch/arm/mach-omap2/clock34xx_data.c
> +++ b/arch/arm/mach-omap2/clock34xx_data.c
> @@ -3240,6 +3240,26 @@ int __init omap3xxx_clk_init(void)
> }
> }
>
> + if (cpu_is_omap3630()) {
> +
> + /*
> + * For 3630: override clkops_omap2_dflt_wait for the
> + * clocks affected from PWRDN reset Limitation
> + */
> + dpll3_m3x2_ck.ops =
> + &clkops_omap3_pwrdn_with_hsdiv_wait_restore;
> + dpll4_m2x2_ck.ops =
> + &clkops_omap3_pwrdn_with_hsdiv_wait_restore;
> + dpll4_m3x2_ck.ops =
> + &clkops_omap3_pwrdn_with_hsdiv_wait_restore;
> + dpll4_m4x2_ck.ops =
> + &clkops_omap3_pwrdn_with_hsdiv_wait_restore;
> + dpll4_m5x2_ck.ops =
> + &clkops_omap3_pwrdn_with_hsdiv_wait_restore;
> + dpll4_m6x2_ck.ops =
> + &clkops_omap3_pwrdn_with_hsdiv_wait_restore;
> + }
> +
> clk_init(&omap2_clk_functions);
>
> for (c = omap3xxx_clks; c < omap3xxx_clks + ARRAY_SIZE(omap3xxx_clks); c++)
> --
> 1.5.6.3
>
- Paul
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