Re: [PATCH v7 07/20] clk: tegra: clk-periph: Add save and restore support

[Dmitry Osipenko]

01.08.2019 20:58, Sowjanya Komatineni ÐÐÑÐÑ:
> 
> On 7/31/19 4:09 PM, Sowjanya Komatineni wrote:
>>
>> On 7/31/19 3:44 AM, Dmitry Osipenko wrote:
>>> 31.07.2019 12:50, Dmitry Osipenko ÐÐÑÐÑ:
>>>> 31.07.2019 3:20, Sowjanya Komatineni ÐÐÑÐÑ:
>>>>> This patch implements save and restore context for peripheral fixed
>>>>> clock ops, peripheral gate clock ops, sdmmc mux clock ops, and
>>>>> peripheral clock ops.
>>>>>
>>>>> During system suspend, core power goes off and looses the settings
>>>>> of the Tegra CAR controller registers.
>>>>>
>>>>> So during suspend entry clock and reset state of peripherals is saved
>>>>> and on resume they are restored to have clocks back to same rate and
>>>>> state as before suspend.
>>>>>
>>>>> Acked-by: Thierry Reding <treding@xxxxxxxxxx>
>>>>> Signed-off-by: Sowjanya Komatineni <skomatineni@xxxxxxxxxx>
>>>>> ---
>>>>> Â drivers/clk/tegra/clk-periph-fixed.c | 33
>>>>> ++++++++++++++++++++++++++++++++
>>>>>  drivers/clk/tegra/clk-periph-gate.c | 34
>>>>> +++++++++++++++++++++++++++++++++
>>>>> Â drivers/clk/tegra/clk-periph.cÂÂÂÂÂÂ | 37
>>>>> ++++++++++++++++++++++++++++++++++++
>>>>> Â drivers/clk/tegra/clk-sdmmc-mux.cÂÂÂ | 28
>>>>> +++++++++++++++++++++++++++
>>>>> Â drivers/clk/tegra/clk.hÂÂÂÂÂÂÂÂÂÂÂÂÂ |Â 6 ++++++
>>>>> Â 5 files changed, 138 insertions(+)
>>>>>
>>>>> diff --git a/drivers/clk/tegra/clk-periph-fixed.c
>>>>> b/drivers/clk/tegra/clk-periph-fixed.c
>>>>> index c088e7a280df..21b24530fa00 100644
>>>>> --- a/drivers/clk/tegra/clk-periph-fixed.c
>>>>> +++ b/drivers/clk/tegra/clk-periph-fixed.c
>>>>> @@ -60,11 +60,44 @@ tegra_clk_periph_fixed_recalc_rate(struct
>>>>> clk_hw *hw,
>>>>> ÂÂÂÂÂ return (unsigned long)rate;
>>>>> Â }
>>>>> Â +static int tegra_clk_periph_fixed_save_context(struct clk_hw *hw)
>>>>> +{
>>>>> +ÂÂÂ struct tegra_clk_periph_fixed *fixed =
>>>>> to_tegra_clk_periph_fixed(hw);
>>>>> +ÂÂÂ u32 mask = 1 << (fixed->num % 32);
>>>>> +
>>>>> +ÂÂÂ fixed->enb_ctx = readl_relaxed(fixed->base +
>>>>> fixed->regs->enb_reg) &
>>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂ mask;
>>>>> +ÂÂÂ fixed->rst_ctx = readl_relaxed(fixed->base +
>>>>> fixed->regs->rst_reg) &
>>>>> +ÂÂÂÂÂÂÂÂÂÂÂÂ mask;
>>>>> +
>>>>> +ÂÂÂ return 0;
>>>>> +}
>>>>> +
>>>>> +static void tegra_clk_periph_fixed_restore_context(struct clk_hw *hw)
>>>>> +{
>>>>> +ÂÂÂ struct tegra_clk_periph_fixed *fixed =
>>>>> to_tegra_clk_periph_fixed(hw);
>>>>> +ÂÂÂ u32 mask = 1 << (fixed->num % 32);
>>>>> +
>>>>> +ÂÂÂ if (fixed->enb_ctx)
>>>>> +ÂÂÂÂÂÂÂ writel_relaxed(mask, fixed->base + fixed->regs->enb_set_reg);
>>>>> +ÂÂÂ else
>>>>> +ÂÂÂÂÂÂÂ writel_relaxed(mask, fixed->base + fixed->regs->enb_clr_reg);
>>>>> +
>>>>> +ÂÂÂ udelay(2);
>>>>> +
>>>>> +ÂÂÂ if (!fixed->rst_ctx) {
>>>>> +ÂÂÂÂÂÂÂ udelay(5); /* reset propogation delay */
>>>>> +ÂÂÂÂÂÂÂ writel_relaxed(mask, fixed->base + fixed->regs->rst_reg);
>>>>> +ÂÂÂ }
>>>>> +}
>>>>> +
>>>>> Â static const struct clk_ops tegra_clk_periph_fixed_ops = {
>>>>> ÂÂÂÂÂ .is_enabled = tegra_clk_periph_fixed_is_enabled,
>>>>> ÂÂÂÂÂ .enable = tegra_clk_periph_fixed_enable,
>>>>> ÂÂÂÂÂ .disable = tegra_clk_periph_fixed_disable,
>>>>> ÂÂÂÂÂ .recalc_rate = tegra_clk_periph_fixed_recalc_rate,
>>>>> +ÂÂÂ .save_context = tegra_clk_periph_fixed_save_context,
>>>>> +ÂÂÂ .restore_context = tegra_clk_periph_fixed_restore_context,
>>>>> Â };
>>>>> Â Â struct clk *tegra_clk_register_periph_fixed(const char *name,
>>>>> diff --git a/drivers/clk/tegra/clk-periph-gate.c
>>>>> b/drivers/clk/tegra/clk-periph-gate.c
>>>>> index 4b31beefc9fc..6ba5b08e0787 100644
>>>>> --- a/drivers/clk/tegra/clk-periph-gate.c
>>>>> +++ b/drivers/clk/tegra/clk-periph-gate.c
>>>>> @@ -25,6 +25,8 @@ static DEFINE_SPINLOCK(periph_ref_lock);
>>>>> Â Â #define read_rst(gate) \
>>>>> ÂÂÂÂÂ readl_relaxed(gate->clk_base + (gate->regs->rst_reg))
>>>>> +#define write_rst_set(val, gate) \
>>>>> +ÂÂÂ writel_relaxed(val, gate->clk_base + (gate->regs->rst_set_reg))
>>>>> Â #define write_rst_clr(val, gate) \
>>>>> ÂÂÂÂÂ writel_relaxed(val, gate->clk_base + (gate->regs->rst_clr_reg))
>>>>> Â @@ -110,10 +112,42 @@ static void clk_periph_disable(struct
>>>>> clk_hw *hw)
>>>>> ÂÂÂÂÂ spin_unlock_irqrestore(&periph_ref_lock, flags);
>>>>> Â }
>>>>> Â +static int clk_periph_gate_save_context(struct clk_hw *hw)
>>>>> +{
>>>>> +ÂÂÂ struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
>>>>> +
>>>>> +ÂÂÂ gate->clk_state_ctx = read_enb(gate) & periph_clk_to_bit(gate);
>>>>> +ÂÂÂ gate->rst_state_ctx = read_rst(gate) & periph_clk_to_bit(gate);
>>>>> +
>>>>> +ÂÂÂ return 0;
>>>>> +}
>>>>> +
>>>>> +static void clk_periph_gate_restore_context(struct clk_hw *hw)
>>>>> +{
>>>>> +ÂÂÂ struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
>>>>> +
>>>>> +ÂÂÂ if (gate->clk_state_ctx)
>>>>> +ÂÂÂÂÂÂÂ write_enb_set(periph_clk_to_bit(gate), gate);
>>>>> +ÂÂÂ else
>>>>> +ÂÂÂÂÂÂÂ write_enb_clr(periph_clk_to_bit(gate), gate);
>>>>> +
>>>>> +ÂÂÂ udelay(5);
>>>>> +
>>>>> +ÂÂÂ if (!(gate->flags & TEGRA_PERIPH_NO_RESET) &&
>>>>> +ÂÂÂÂÂÂÂ !(gate->flags & TEGRA_PERIPH_MANUAL_RESET)) {
>>>>> +ÂÂÂÂÂÂÂ if (gate->rst_state_ctx)
>>>>> +ÂÂÂÂÂÂÂÂÂÂÂ write_rst_set(periph_clk_to_bit(gate), gate);
>>>>> +ÂÂÂÂÂÂÂ else
>>>>> +ÂÂÂÂÂÂÂÂÂÂÂ write_rst_clr(periph_clk_to_bit(gate), gate);
>>>>> +ÂÂÂ }
>>>>> +}
>>>>> +
>>>>> Â const struct clk_ops tegra_clk_periph_gate_ops = {
>>>>> ÂÂÂÂÂ .is_enabled = clk_periph_is_enabled,
>>>>> ÂÂÂÂÂ .enable = clk_periph_enable,
>>>>> ÂÂÂÂÂ .disable = clk_periph_disable,
>>>>> +ÂÂÂ .save_context = clk_periph_gate_save_context,
>>>>> +ÂÂÂ .restore_context = clk_periph_gate_restore_context,
>>>>> Â };
>>>>> Â Â struct clk *tegra_clk_register_periph_gate(const char *name,
>>>>> diff --git a/drivers/clk/tegra/clk-periph.c
>>>>> b/drivers/clk/tegra/clk-periph.c
>>>>> index 58437da25156..06fb62955768 100644
>>>>> --- a/drivers/clk/tegra/clk-periph.c
>>>>> +++ b/drivers/clk/tegra/clk-periph.c
>>>>> @@ -99,6 +99,37 @@ static void clk_periph_disable(struct clk_hw *hw)
>>>>> ÂÂÂÂÂ gate_ops->disable(gate_hw);
>>>>> Â }
>>>>> Â +static int clk_periph_save_context(struct clk_hw *hw)
>>>>> +{
>>>>> +ÂÂÂ struct tegra_clk_periph *periph = to_clk_periph(hw);
>>>>> +ÂÂÂ const struct clk_ops *gate_ops = periph->gate_ops;
>>>>> +ÂÂÂ struct clk_hw *gate_hw = &periph->gate.hw;
>>>>> +
>>>>> +ÂÂÂ if (!(periph->gate.flags & TEGRA_PERIPH_NO_GATE))
>>>>> +ÂÂÂÂÂÂÂ gate_ops->save_context(gate_hw);
>>>>> +
>>>>> +ÂÂÂ periph->parent_ctx = clk_periph_get_parent(hw);
>>>>> +
>>>>> +ÂÂÂ return 0;
>>>>> +}
>>>>> +
>>>>> +static void clk_periph_restore_context(struct clk_hw *hw)
>>>>> +{
>>>>> +ÂÂÂ struct tegra_clk_periph *periph = to_clk_periph(hw);
>>>>> +ÂÂÂ const struct clk_ops *gate_ops = periph->gate_ops;
>>>>> +ÂÂÂ struct clk_hw *gate_hw = &periph->gate.hw;
>>>>> +ÂÂÂ const struct clk_ops *div_ops = periph->div_ops;
>>>>> +ÂÂÂ struct clk_hw *div_hw = &periph->divider.hw;
>>>>> +
>>>>> +ÂÂÂ clk_periph_set_parent(hw, periph->parent_ctx);
>>>>> +
>>>>> +ÂÂÂ if (!(periph->gate.flags & TEGRA_PERIPH_NO_DIV))
>>>>> +ÂÂÂÂÂÂÂ div_ops->restore_context(div_hw);
>>>> Could you please point to where the divider's save_context() happens?
>>>> Because I can't see it.
>>> Ah, I now see that there is no need to save the dividers context because
>>> clk itself has enough info that is needed for the context's restoring
>>> (like I pointed in the review to v6).
>>>
>>> Looks like you could also implement a new clk_hw_get_parent_index()
>>> generic helper to get the index instead of storing it manually.
>>
>> clk_periph_get_parent basically invokes existing clk_mux_ops
>> get_parent() which is then saved in tegra_clk_periph.
>>
>> All existing drivers are using directly get_parent() from clk_mux
>> which actually gets index from the register read.
>>
>> To have this more generic w.r.t save/restore context point of view,
>> probably instead of implementing new get_parent_index helper, I think
>> its better to implement save_context and restore_context to
>> clk_mux_ops along with creating parent_index field into clk_mux to
>> cache index during set_parent.
>>
>> So we just need to invoke mux_ops save_context and restore_context.
>>
> I hope its ok to add save/restore context to clk_mux_ops to be more
> generic w.r.t save/restore context rather than get_parent_index API.
> Please confirm if you agree.

Sounds like a good idea. I see that there is a 'restoring' helper for
the generic clk_gate, seems something similar could be done for the
clk_mux. And looks like anyway you'll need to associate the parent clock
with the hw index in order to restore the muxing.