From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Osipenko Subject: Re: [PATCH v7 07/20] clk: tegra: clk-periph: Add save and restore support Date: Thu, 1 Aug 2019 22:00:55 +0300 Message-ID: References: <1564532424-10449-1-git-send-email-skomatineni@nvidia.com> <1564532424-10449-8-git-send-email-skomatineni@nvidia.com> <67cf6c13-688d-0305-61e2-c63c8e8b4729@nvidia.com> <550de191-f982-4544-6fbc-bf16dfeae2c6@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <550de191-f982-4544-6fbc-bf16dfeae2c6@nvidia.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Sowjanya Komatineni , thierry.reding@gmail.com, jonathanh@nvidia.com, tglx@linutronix.de, jason@lakedaemon.net, marc.zyngier@arm.com, linus.walleij@linaro.org, stefan@agner.ch, mark.rutland@arm.com Cc: pdeschrijver@nvidia.com, pgaikwad@nvidia.com, sboyd@kernel.org, linux-clk@vger.kernel.org, linux-gpio@vger.kernel.org, jckuo@nvidia.com, josephl@nvidia.com, talho@nvidia.com, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, mperttunen@nvidia.com, spatra@nvidia.com, robh+dt@kernel.org, devicetree@vger.kernel.org List-Id: devicetree@vger.kernel.org 01.08.2019 20:58, Sowjanya Komatineni пишет: > > 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 >>>>> Signed-off-by: Sowjanya Komatineni >>>>> --- >>>>>   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. 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.