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SubjectRe: [PATCH v4 6/9] clk: at91: clk-generated: make gclk determine audio_pll rate
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Date
On 25/07/2017 at 09:37, Quentin Schulz wrote:
> This allows gclk to determine audio_pll rate and set the parent rate
> accordingly.
>
> However, there are multiple children clocks that could technically
> change the rate of audio_pll (via gck). With the rate locking, the first
> consumer to enable the clock will be the one definitely setting the rate
> of the clock.
>
> Since audio IPs are most likely to request the same rate, we enforce
> that the only clks able to modify gck rate are those of audio IPs.
>
> To remain consistent, we deny other clocks to be children of audio_pll.
>
> Signed-off-by: Quentin Schulz <quentin.schulz@free-electrons.com>
> Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>

Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>

> ---
> drivers/clk/at91/clk-generated.c | 63 +++++++++++++++++++++++++++++----
> 1 file changed, 57 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/clk/at91/clk-generated.c b/drivers/clk/at91/clk-generated.c
> index 7260e49..3348136 100644
> --- a/drivers/clk/at91/clk-generated.c
> +++ b/drivers/clk/at91/clk-generated.c
> @@ -26,6 +26,13 @@
> #define GENERATED_SOURCE_MAX 6
> #define GENERATED_MAX_DIV 255
>
> +#define GCK_ID_SSC0 43
> +#define GCK_ID_SSC1 44
> +#define GCK_ID_I2S0 54
> +#define GCK_ID_I2S1 55
> +#define GCK_ID_CLASSD 59
> +#define GCK_INDEX_DT_AUDIO_PLL 5
> +
> struct clk_generated {
> struct clk_hw hw;
> struct regmap *regmap;
> @@ -34,6 +41,7 @@ struct clk_generated {
> u32 id;
> u32 gckdiv;
> u8 parent_id;
> + bool audio_pll_allowed;
> };
>
> #define to_clk_generated(hw) \
> @@ -126,15 +134,14 @@ static int clk_generated_determine_rate(struct clk_hw *hw,
> {
> struct clk_generated *gck = to_clk_generated(hw);
> struct clk_hw *parent = NULL;
> + struct clk_rate_request req_parent = *req;
> long best_rate = -EINVAL;
> - unsigned long min_rate;
> + unsigned long min_rate, parent_rate;
> int best_diff = -1;
> int i;
> + u32 div;
>
> - for (i = 0; i < clk_hw_get_num_parents(hw); i++) {
> - u32 div;
> - unsigned long parent_rate;
> -
> + for (i = 0; i < clk_hw_get_num_parents(hw) - 1; i++) {
> parent = clk_hw_get_parent_by_index(hw, i);
> if (!parent)
> continue;
> @@ -150,11 +157,38 @@ static int clk_generated_determine_rate(struct clk_hw *hw,
> clk_generated_best_diff(req, parent, parent_rate, div,
> &best_diff, &best_rate);
>
> + if (!best_diff)
> + break;
> + }
> +
> + /*
> + * The audio_pll rate can be modified, unlike the five others clocks
> + * that should never be altered.
> + * The audio_pll can technically be used by multiple consumers. However,
> + * with the rate locking, the first consumer to enable to clock will be
> + * the one definitely setting the rate of the clock.
> + * Since audio IPs are most likely to request the same rate, we enforce
> + * that the only clks able to modify gck rate are those of audio IPs.
> + */
> +
> + if (!gck->audio_pll_allowed)
> + goto end;
> +
> + parent = clk_hw_get_parent_by_index(hw, GCK_INDEX_DT_AUDIO_PLL);
> + if (!parent)
> + goto end;
> +
> + for (div = 1; div < GENERATED_MAX_DIV + 2; div++) {
> + req_parent.rate = req->rate * div;
> + __clk_determine_rate(parent, &req_parent);
> + clk_generated_best_diff(req, parent, req_parent.rate, div,
> + &best_diff, &best_rate);
>
> if (!best_diff)
> break;
> }
>
> +end:
> pr_debug("GCLK: %s, best_rate = %ld, parent clk: %s @ %ld\n",
> __func__, best_rate,
> __clk_get_name((req->best_parent_hw)->clk),
> @@ -264,7 +298,8 @@ at91_clk_register_generated(struct regmap *regmap, spinlock_t *lock,
> init.ops = &generated_ops;
> init.parent_names = parent_names;
> init.num_parents = num_parents;
> - init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE;
> + init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE |
> + CLK_SET_RATE_PARENT;
>
> gck->id = id;
> gck->hw.init = &init;
> @@ -296,6 +331,7 @@ static void __init of_sama5d2_clk_generated_setup(struct device_node *np)
> struct device_node *gcknp;
> struct clk_range range = CLK_RANGE(0, 0);
> struct regmap *regmap;
> + struct clk_generated *gck;
>
> num_parents = of_clk_get_parent_count(np);
> if (num_parents == 0 || num_parents > GENERATED_SOURCE_MAX)
> @@ -327,6 +363,21 @@ static void __init of_sama5d2_clk_generated_setup(struct device_node *np)
> hw = at91_clk_register_generated(regmap, &pmc_pcr_lock, name,
> parent_names, num_parents,
> id, &range);
> +
> + gck = to_clk_generated(hw);
> +
> + if (of_device_is_compatible(np,
> + "atmel,sama5d2-clk-generated")) {
> + if (gck->id == GCK_ID_SSC0 || gck->id == GCK_ID_SSC1 ||
> + gck->id == GCK_ID_I2S0 || gck->id == GCK_ID_I2S1 ||
> + gck->id == GCK_ID_CLASSD)
> + gck->audio_pll_allowed = true;
> + else
> + gck->audio_pll_allowed = false;
> + } else {
> + gck->audio_pll_allowed = false;
> + }
> +
> if (IS_ERR(hw))
> continue;
>
>


--
Nicolas Ferre

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