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Date: Wed, 31 Jul 2019 16:09:53 -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 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.
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