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Date: Thu, 1 Aug 2019 10:58:40 -0700
From: Sowjanya Komatineni <skomatineni@...dia.com>
To: Dmitry Osipenko <digetx@...il.com>, <thierry.reding@...il.com>,
<jonathanh@...dia.com>, <tglx@...utronix.de>,
<jason@...edaemon.net>, <marc.zyngier@....com>,
<linus.walleij@...aro.org>, <stefan@...er.ch>,
<mark.rutland@....com>
CC: <pdeschrijver@...dia.com>, <pgaikwad@...dia.com>,
<sboyd@...nel.org>, <linux-clk@...r.kernel.org>,
<linux-gpio@...r.kernel.org>, <jckuo@...dia.com>,
<josephl@...dia.com>, <talho@...dia.com>,
<linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<mperttunen@...dia.com>, <spatra@...dia.com>, <robh+dt@...nel.org>,
<devicetree@...r.kernel.org>
Subject: Re: [PATCH v7 07/20] clk: tegra: clk-periph: Add save and restore
support
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 пишет:
>>> 31.07.2019 3:20, Sowjanya Komatineni пишет:
>>>> 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@...dia.com>
>>>> Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
>>>> ---
>>>> drivers/clk/tegra/clk-periph-fixed.c | 33
>>>> ++++++++++++++++++++++++++++++++
>>>> drivers/clk/tegra/clk-periph-gate.c | 34
>>>> +++++++++++++++++++++++++++++++++
>>>> drivers/clk/tegra/clk-periph.c | 37
>>>> ++++++++++++++++++++++++++++++++++++
>>>> drivers/clk/tegra/clk-sdmmc-mux.c | 28
>>>> +++++++++++++++++++++++++++
>>>> drivers/clk/tegra/clk.h | 6 ++++++
>>>> 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,
>>>> return (unsigned long)rate;
>>>> }
>>>> +static int tegra_clk_periph_fixed_save_context(struct clk_hw *hw)
>>>> +{
>>>> + struct tegra_clk_periph_fixed *fixed =
>>>> to_tegra_clk_periph_fixed(hw);
>>>> + u32 mask = 1 << (fixed->num % 32);
>>>> +
>>>> + fixed->enb_ctx = readl_relaxed(fixed->base +
>>>> fixed->regs->enb_reg) &
>>>> + mask;
>>>> + fixed->rst_ctx = readl_relaxed(fixed->base +
>>>> fixed->regs->rst_reg) &
>>>> + mask;
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static void tegra_clk_periph_fixed_restore_context(struct clk_hw *hw)
>>>> +{
>>>> + struct tegra_clk_periph_fixed *fixed =
>>>> to_tegra_clk_periph_fixed(hw);
>>>> + u32 mask = 1 << (fixed->num % 32);
>>>> +
>>>> + if (fixed->enb_ctx)
>>>> + writel_relaxed(mask, fixed->base + fixed->regs->enb_set_reg);
>>>> + else
>>>> + writel_relaxed(mask, fixed->base + fixed->regs->enb_clr_reg);
>>>> +
>>>> + udelay(2);
>>>> +
>>>> + if (!fixed->rst_ctx) {
>>>> + udelay(5); /* reset propogation delay */
>>>> + writel_relaxed(mask, fixed->base + fixed->regs->rst_reg);
>>>> + }
>>>> +}
>>>> +
>>>> static const struct clk_ops tegra_clk_periph_fixed_ops = {
>>>> .is_enabled = tegra_clk_periph_fixed_is_enabled,
>>>> .enable = tegra_clk_periph_fixed_enable,
>>>> .disable = tegra_clk_periph_fixed_disable,
>>>> .recalc_rate = tegra_clk_periph_fixed_recalc_rate,
>>>> + .save_context = tegra_clk_periph_fixed_save_context,
>>>> + .restore_context = tegra_clk_periph_fixed_restore_context,
>>>> };
>>>> 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);
>>>> #define read_rst(gate) \
>>>> readl_relaxed(gate->clk_base + (gate->regs->rst_reg))
>>>> +#define write_rst_set(val, gate) \
>>>> + writel_relaxed(val, gate->clk_base + (gate->regs->rst_set_reg))
>>>> #define write_rst_clr(val, gate) \
>>>> writel_relaxed(val, gate->clk_base + (gate->regs->rst_clr_reg))
>>>> @@ -110,10 +112,42 @@ static void clk_periph_disable(struct
>>>> clk_hw *hw)
>>>> spin_unlock_irqrestore(&periph_ref_lock, flags);
>>>> }
>>>> +static int clk_periph_gate_save_context(struct clk_hw *hw)
>>>> +{
>>>> + struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
>>>> +
>>>> + gate->clk_state_ctx = read_enb(gate) & periph_clk_to_bit(gate);
>>>> + gate->rst_state_ctx = read_rst(gate) & periph_clk_to_bit(gate);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static void clk_periph_gate_restore_context(struct clk_hw *hw)
>>>> +{
>>>> + struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
>>>> +
>>>> + if (gate->clk_state_ctx)
>>>> + write_enb_set(periph_clk_to_bit(gate), gate);
>>>> + else
>>>> + write_enb_clr(periph_clk_to_bit(gate), gate);
>>>> +
>>>> + udelay(5);
>>>> +
>>>> + if (!(gate->flags & TEGRA_PERIPH_NO_RESET) &&
>>>> + !(gate->flags & TEGRA_PERIPH_MANUAL_RESET)) {
>>>> + if (gate->rst_state_ctx)
>>>> + write_rst_set(periph_clk_to_bit(gate), gate);
>>>> + else
>>>> + write_rst_clr(periph_clk_to_bit(gate), gate);
>>>> + }
>>>> +}
>>>> +
>>>> const struct clk_ops tegra_clk_periph_gate_ops = {
>>>> .is_enabled = clk_periph_is_enabled,
>>>> .enable = clk_periph_enable,
>>>> .disable = clk_periph_disable,
>>>> + .save_context = clk_periph_gate_save_context,
>>>> + .restore_context = clk_periph_gate_restore_context,
>>>> };
>>>> 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)
>>>> gate_ops->disable(gate_hw);
>>>> }
>>>> +static int clk_periph_save_context(struct clk_hw *hw)
>>>> +{
>>>> + struct tegra_clk_periph *periph = to_clk_periph(hw);
>>>> + const struct clk_ops *gate_ops = periph->gate_ops;
>>>> + struct clk_hw *gate_hw = &periph->gate.hw;
>>>> +
>>>> + if (!(periph->gate.flags & TEGRA_PERIPH_NO_GATE))
>>>> + gate_ops->save_context(gate_hw);
>>>> +
>>>> + periph->parent_ctx = clk_periph_get_parent(hw);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static void clk_periph_restore_context(struct clk_hw *hw)
>>>> +{
>>>> + struct tegra_clk_periph *periph = to_clk_periph(hw);
>>>> + const struct clk_ops *gate_ops = periph->gate_ops;
>>>> + struct clk_hw *gate_hw = &periph->gate.hw;
>>>> + const struct clk_ops *div_ops = periph->div_ops;
>>>> + struct clk_hw *div_hw = &periph->divider.hw;
>>>> +
>>>> + clk_periph_set_parent(hw, periph->parent_ctx);
>>>> +
>>>> + if (!(periph->gate.flags & TEGRA_PERIPH_NO_DIV))
>>>> + 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.
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