Re: [PATCH] clk: Add functions to save and restore clock/dpll context en-masse

From: Keerthy
Date: Thu May 04 2017 - 04:27:26 EST

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In reply to: Tero Kristo: "Re: [PATCH] clk: Add functions to save and restore clock/dpll context en-masse"
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On Thursday 04 May 2017 01:47 PM, Tero Kristo wrote:
> On 04/05/17 10:51, Peter De Schrijver wrote:
>> On Tue, Apr 18, 2017 at 10:42:49AM +0530, Keerthy wrote:
>>> From: Russ Dill <Russ.Dill@xxxxxx>
>>>
>>> The clock/dpll registers are in the WKUP power domain. Under both
>>> RTC-only
>>> suspend and hibernation, these registers are lost. Hence save/restore
>>> them accordingly.
>>>
>>
>> This won't work for Tegra, because we need a 2 pass restore. First
>> restore
>> rate/parents with all clocks enabled and then disable the ones which were
>> disabled before entering suspend. Both passes usually go from root to
>> leave.
>> However a few clocks have to be treated separately, eg the ones
>> related to
>> SDRAM.
>
> Do you have your own implementation in place? Is it possible to modify
> the base code here to add your requirements (drivers/clk/clk.c)?
>
> I guess we could also just add clk_for_each() type of call that would
> allow us to iterate over clock hierarchy.

Any patch links to your implementation could be very helpful.

>
> -Tero
>
>>
>>
>>> Signed-off-by: Russ Dill <Russ.Dill@xxxxxx>
>>> Signed-off-by: Keerthy <j-keerthy@xxxxxx>
>>> ---
>>> drivers/clk/clk.c | 70 ++++++++++++++++++++++++
>>> drivers/clk/ti/divider.c | 36 +++++++++++++
>>> drivers/clk/ti/dpll.c | 6 +++
>>> drivers/clk/ti/dpll3xxx.c | 124
>>> +++++++++++++++++++++++++++++++++++++++++++
>>> drivers/clk/ti/gate.c | 3 ++
>>> drivers/clk/ti/mux.c | 29 ++++++++++
>>> include/linux/clk-provider.h | 11 ++++
>>> include/linux/clk.h | 25 +++++++++
>>> include/linux/clk/ti.h | 6 +++
>>> 9 files changed, 310 insertions(+)
>>>
>>> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
>>> index cddddbe..1ca87f4 100644
>>> --- a/drivers/clk/clk.c
>>> +++ b/drivers/clk/clk.c
>>> @@ -687,6 +687,76 @@ static int clk_core_enable_lock(struct clk_core
>>> *core)
>>> return ret;
>>> }
>>>
>>> +void clk_dflt_restore_context(struct clk_hw *hw)
>>> +{
>>> + if (hw->clk->core->enable_count)
>>> + hw->clk->core->ops->enable(hw);
>>> + else
>>> + hw->clk->core->ops->disable(hw);
>>> +}
>>> +EXPORT_SYMBOL_GPL(clk_dflt_restore_context);
>>> +
>>> +static int clk_save_context(struct clk_core *clk)
>>> +{
>>> + struct clk_core *child;
>>> + int ret = 0;
>>> +
>>> + hlist_for_each_entry(child, &clk->children, child_node) {
>>> + ret = clk_save_context(child);
>>> + if (ret < 0)
>>> + return ret;
>>> + }
>>> +
>>> + if (clk->ops && clk->ops->save_context)
>>> + ret = clk->ops->save_context(clk->hw);
>>> +
>>> + return ret;
>>> +}
>>> +
>>> +static void clk_restore_context(struct clk_core *clk)
>>> +{
>>> + struct clk_core *child;
>>> +
>>> + if (clk->ops && clk->ops->restore_context)
>>> + clk->ops->restore_context(clk->hw);
>>> +
>>> + hlist_for_each_entry(child, &clk->children, child_node)
>>> + clk_restore_context(child);
>>> +}
>>> +
>>> +int clks_save_context(void)
>>> +{
>>> + struct clk_core *clk;
>>> + int ret;
>>> +
>>> + hlist_for_each_entry(clk, &clk_root_list, child_node) {
>>> + ret = clk_save_context(clk);
>>> + if (ret < 0)
>>> + return ret;
>>> + }
>>> +
>>> + hlist_for_each_entry(clk, &clk_orphan_list, child_node) {
>>> + ret = clk_save_context(clk);
>>> + if (ret < 0)
>>> + return ret;
>>> + }
>>> +
>>> + return 0;
>>> +}
>>> +EXPORT_SYMBOL_GPL(clks_save_context);
>>> +
>>> +void clks_restore_context(void)
>>> +{
>>> + struct clk_core *clk;
>>> +
>>> + hlist_for_each_entry(clk, &clk_root_list, child_node)
>>> + clk_restore_context(clk);
>>> +
>>> + hlist_for_each_entry(clk, &clk_orphan_list, child_node)
>>> + clk_restore_context(clk);
>>> +}
>>> +EXPORT_SYMBOL_GPL(clks_restore_context);
>>> +
>>> /**
>>> * clk_enable - ungate a clock
>>> * @clk: the clk being ungated
>>> diff --git a/drivers/clk/ti/divider.c b/drivers/clk/ti/divider.c
>>> index d6dcb28..350a58a 100644
>>> --- a/drivers/clk/ti/divider.c
>>> +++ b/drivers/clk/ti/divider.c
>>> @@ -266,10 +266,46 @@ static int ti_clk_divider_set_rate(struct
>>> clk_hw *hw, unsigned long rate,
>>> return 0;
>>> }
>>>
>>> +/**
>>> + * clk_divider_save_context - Save the divider value
>>> + * @hw: pointer struct clk_hw
>>> + *
>>> + * Save the divider value
>>> + */
>>> +static int clk_divider_save_context(struct clk_hw *hw)
>>> +{
>>> + struct clk_divider *divider = to_clk_divider(hw);
>>> + u32 val;
>>> +
>>> + val = ti_clk_ll_ops->clk_readl(divider->reg) >> divider->shift;
>>> + divider->context = val & div_mask(divider);
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +/**
>>> + * clk_divider_restore_context - restore the saved the divider value
>>> + * @hw: pointer struct clk_hw
>>> + *
>>> + * Restore the saved the divider value
>>> + */
>>> +static void clk_divider_restore_context(struct clk_hw *hw)
>>> +{
>>> + struct clk_divider *divider = to_clk_divider(hw);
>>> + u32 val;
>>> +
>>> + val = ti_clk_ll_ops->clk_readl(divider->reg);
>>> + val &= ~(div_mask(divider) << divider->shift);
>>> + val |= divider->context << divider->shift;
>>> + ti_clk_ll_ops->clk_writel(val, divider->reg);
>>> +}
>>> +
>>> const struct clk_ops ti_clk_divider_ops = {
>>> .recalc_rate = ti_clk_divider_recalc_rate,
>>> .round_rate = ti_clk_divider_round_rate,
>>> .set_rate = ti_clk_divider_set_rate,
>>> + .save_context = clk_divider_save_context,
>>> + .restore_context = clk_divider_restore_context,
>>> };
>>>
>>> static struct clk *_register_divider(struct device *dev, const char
>>> *name,
>>> diff --git a/drivers/clk/ti/dpll.c b/drivers/clk/ti/dpll.c
>>> index 96d8488..791dd31 100644
>>> --- a/drivers/clk/ti/dpll.c
>>> +++ b/drivers/clk/ti/dpll.c
>>> @@ -39,6 +39,8 @@
>>> .set_rate_and_parent = &omap3_noncore_dpll_set_rate_and_parent,
>>> .determine_rate = &omap4_dpll_regm4xen_determine_rate,
>>> .get_parent = &omap2_init_dpll_parent,
>>> + .save_context = &omap3_core_dpll_save_context,
>>> + .restore_context = &omap3_core_dpll_restore_context,
>>> };
>>> #else
>>> static const struct clk_ops dpll_m4xen_ck_ops = {};
>>> @@ -62,6 +64,8 @@
>>> .set_rate_and_parent = &omap3_noncore_dpll_set_rate_and_parent,
>>> .determine_rate = &omap3_noncore_dpll_determine_rate,
>>> .get_parent = &omap2_init_dpll_parent,
>>> + .save_context = &omap3_noncore_dpll_save_context,
>>> + .restore_context = &omap3_noncore_dpll_restore_context,
>>> };
>>>
>>> static const struct clk_ops dpll_no_gate_ck_ops = {
>>> @@ -72,6 +76,8 @@
>>> .set_parent = &omap3_noncore_dpll_set_parent,
>>> .set_rate_and_parent = &omap3_noncore_dpll_set_rate_and_parent,
>>> .determine_rate = &omap3_noncore_dpll_determine_rate,
>>> + .save_context = &omap3_noncore_dpll_save_context,
>>> + .restore_context = &omap3_noncore_dpll_restore_context
>>> };
>>> #else
>>> static const struct clk_ops dpll_core_ck_ops = {};
>>> diff --git a/drivers/clk/ti/dpll3xxx.c b/drivers/clk/ti/dpll3xxx.c
>>> index 4534de2..44b6b64 100644
>>> --- a/drivers/clk/ti/dpll3xxx.c
>>> +++ b/drivers/clk/ti/dpll3xxx.c
>>> @@ -782,6 +782,130 @@ unsigned long omap3_clkoutx2_recalc(struct
>>> clk_hw *hw,
>>> return rate;
>>> }
>>>
>>> +/**
>>> + * omap3_core_dpll_save_context - Save the m and n values of the
>>> divider
>>> + * @hw: pointer struct clk_hw
>>> + *
>>> + * Before the dpll registers are lost save the last rounded rate m
>>> and n
>>> + * and the enable mask.
>>> + */
>>> +int omap3_core_dpll_save_context(struct clk_hw *hw)
>>> +{
>>> + struct clk_hw_omap *clk = to_clk_hw_omap(hw);
>>> + struct dpll_data *dd;
>>> + u32 v;
>>> +
>>> + dd = clk->dpll_data;
>>> +
>>> + v = ti_clk_ll_ops->clk_readl(&dd->control_reg);
>>> + clk->context = (v & dd->enable_mask) >> __ffs(dd->enable_mask);
>>> +
>>> + if (clk->context == DPLL_LOCKED) {
>>> + v = ti_clk_ll_ops->clk_readl(&dd->mult_div1_reg);
>>> + dd->last_rounded_m = (v & dd->mult_mask) >>
>>> + __ffs(dd->mult_mask);
>>> + dd->last_rounded_n = ((v & dd->div1_mask) >>
>>> + __ffs(dd->div1_mask)) + 1;
>>> + }
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +/**
>>> + * omap3_core_dpll_restore_context - restore the m and n values of
>>> the divider
>>> + * @hw: pointer struct clk_hw
>>> + *
>>> + * Restore the last rounded rate m and n
>>> + * and the enable mask.
>>> + */
>>> +void omap3_core_dpll_restore_context(struct clk_hw *hw)
>>> +{
>>> + struct clk_hw_omap *clk = to_clk_hw_omap(hw);
>>> + const struct dpll_data *dd;
>>> + u32 v;
>>> +
>>> + dd = clk->dpll_data;
>>> +
>>> + if (clk->context == DPLL_LOCKED) {
>>> + _omap3_dpll_write_clken(clk, 0x4);
>>> + _omap3_wait_dpll_status(clk, 0);
>>> +
>>> + v = ti_clk_ll_ops->clk_readl(&dd->mult_div1_reg);
>>> + v &= ~(dd->mult_mask | dd->div1_mask);
>>> + v |= dd->last_rounded_m << __ffs(dd->mult_mask);
>>> + v |= (dd->last_rounded_n - 1) << __ffs(dd->div1_mask);
>>> + ti_clk_ll_ops->clk_writel(v, &dd->mult_div1_reg);
>>> +
>>> + _omap3_dpll_write_clken(clk, DPLL_LOCKED);
>>> + _omap3_wait_dpll_status(clk, 1);
>>> + } else {
>>> + _omap3_dpll_write_clken(clk, clk->context);
>>> + }
>>> +}
>>> +
>>> +/**
>>> + * omap3_non_core_dpll_save_context - Save the m and n values of the
>>> divider
>>> + * @hw: pointer struct clk_hw
>>> + *
>>> + * Before the dpll registers are lost save the last rounded rate m
>>> and n
>>> + * and the enable mask.
>>> + */
>>> +int omap3_noncore_dpll_save_context(struct clk_hw *hw)
>>> +{
>>> + struct clk_hw_omap *clk = to_clk_hw_omap(hw);
>>> + struct dpll_data *dd;
>>> + u32 v;
>>> +
>>> + dd = clk->dpll_data;
>>> +
>>> + v = ti_clk_ll_ops->clk_readl(&dd->control_reg);
>>> + clk->context = (v & dd->enable_mask) >> __ffs(dd->enable_mask);
>>> +
>>> + if (clk->context == DPLL_LOCKED) {
>>> + v = ti_clk_ll_ops->clk_readl(&dd->mult_div1_reg);
>>> + dd->last_rounded_m = (v & dd->mult_mask) >>
>>> + __ffs(dd->mult_mask);
>>> + dd->last_rounded_n = ((v & dd->div1_mask) >>
>>> + __ffs(dd->div1_mask)) + 1;
>>> + }
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +/**
>>> + * omap3_core_dpll_restore_context - restore the m and n values of
>>> the divider
>>> + * @hw: pointer struct clk_hw
>>> + *
>>> + * Restore the last rounded rate m and n
>>> + * and the enable mask.
>>> + */
>>> +void omap3_noncore_dpll_restore_context(struct clk_hw *hw)
>>> +{
>>> + struct clk_hw_omap *clk = to_clk_hw_omap(hw);
>>> + const struct dpll_data *dd;
>>> + u32 ctrl, mult_div1;
>>> +
>>> + dd = clk->dpll_data;
>>> +
>>> + ctrl = ti_clk_ll_ops->clk_readl(&dd->control_reg);
>>> + mult_div1 = ti_clk_ll_ops->clk_readl(&dd->mult_div1_reg);
>>> +
>>> + if (clk->context == ((ctrl & dd->enable_mask) >>
>>> + __ffs(dd->enable_mask)) &&
>>> + dd->last_rounded_m == ((mult_div1 & dd->mult_mask) >>
>>> + __ffs(dd->mult_mask)) &&
>>> + dd->last_rounded_n == ((mult_div1 & dd->div1_mask) >>
>>> + __ffs(dd->div1_mask)) + 1) {
>>> + /* nothing to be done */
>>> + return;
>>> + }
>>> +
>>> + if (clk->context == DPLL_LOCKED)
>>> + omap3_noncore_dpll_program(clk, 0);
>>> + else
>>> + _omap3_dpll_write_clken(clk, clk->context);
>>> +}
>>> +
>>> /* OMAP3/4 non-CORE DPLL clkops */
>>> const struct clk_hw_omap_ops clkhwops_omap3_dpll = {
>>> .allow_idle = omap3_dpll_allow_idle,
>>> diff --git a/drivers/clk/ti/gate.c b/drivers/clk/ti/gate.c
>>> index 7151ec3..098db66 100644
>>> --- a/drivers/clk/ti/gate.c
>>> +++ b/drivers/clk/ti/gate.c
>>> @@ -33,6 +33,7 @@
>>> .init = &omap2_init_clk_clkdm,
>>> .enable = &omap2_clkops_enable_clkdm,
>>> .disable = &omap2_clkops_disable_clkdm,
>>> + .restore_context = clk_dflt_restore_context,
>>> };
>>>
>>> const struct clk_ops omap_gate_clk_ops = {
>>> @@ -40,6 +41,7 @@
>>> .enable = &omap2_dflt_clk_enable,
>>> .disable = &omap2_dflt_clk_disable,
>>> .is_enabled = &omap2_dflt_clk_is_enabled,
>>> + .restore_context = clk_dflt_restore_context,
>>> };
>>>
>>> static const struct clk_ops omap_gate_clk_hsdiv_restore_ops = {
>>> @@ -47,6 +49,7 @@
>>> .enable = &omap36xx_gate_clk_enable_with_hsdiv_restore,
>>> .disable = &omap2_dflt_clk_disable,
>>> .is_enabled = &omap2_dflt_clk_is_enabled,
>>> + .restore_context = clk_dflt_restore_context,
>>> };
>>>
>>> /**
>>> diff --git a/drivers/clk/ti/mux.c b/drivers/clk/ti/mux.c
>>> index 18c267b..e73764a 100644
>>> --- a/drivers/clk/ti/mux.c
>>> +++ b/drivers/clk/ti/mux.c
>>> @@ -90,10 +90,39 @@ static int ti_clk_mux_set_parent(struct clk_hw
>>> *hw, u8 index)
>>> return 0;
>>> }
>>>
>>> +/**
>>> + * clk_mux_save_context - Save the parent selcted in the mux
>>> + * @hw: pointer struct clk_hw
>>> + *
>>> + * Save the parent mux value.
>>> + */
>>> +static int clk_mux_save_context(struct clk_hw *hw)
>>> +{
>>> + struct clk_mux *mux = to_clk_mux(hw);
>>> +
>>> + mux->saved_parent = ti_clk_mux_get_parent(hw);
>>> + return 0;
>>> +}
>>> +
>>> +/**
>>> + * clk_mux_restore_context - Restore the parent in the mux
>>> + * @hw: pointer struct clk_hw
>>> + *
>>> + * Restore the saved parent mux value.
>>> + */
>>> +static void clk_mux_restore_context(struct clk_hw *hw)
>>> +{
>>> + struct clk_mux *mux = to_clk_mux(hw);
>>> +
>>> + ti_clk_mux_set_parent(hw, mux->saved_parent);
>>> +}
>>> +
>>> const struct clk_ops ti_clk_mux_ops = {
>>> .get_parent = ti_clk_mux_get_parent,
>>> .set_parent = ti_clk_mux_set_parent,
>>> .determine_rate = __clk_mux_determine_rate,
>>> + .save_context = clk_mux_save_context,
>>> + .restore_context = clk_mux_restore_context,
>>> };
>>>
>>> static struct clk *_register_mux(struct device *dev, const char *name,
>>> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
>>> index a428aec..2a8f636 100644
>>> --- a/include/linux/clk-provider.h
>>> +++ b/include/linux/clk-provider.h
>>> @@ -103,6 +103,11 @@ struct clk_rate_request {
>>> * Called with enable_lock held. This function must not
>>> * sleep.
>>> *
>>> + * @save_context: Save the context of the clock in prepration for
>>> poweroff.
>>> + *
>>> + * @restore_context: Restore the context of the clock after a
>>> restoration
>>> + * of power.
>>> + *
>>> * @recalc_rate Recalculate the rate of this clock, by querying
>>> hardware. The
>>> * parent rate is an input parameter. It is up to the caller to
>>> * ensure that the prepare_mutex is held across this call.
>>> @@ -198,6 +203,8 @@ struct clk_ops {
>>> void (*disable)(struct clk_hw *hw);
>>> int (*is_enabled)(struct clk_hw *hw);
>>> void (*disable_unused)(struct clk_hw *hw);
>>> + int (*save_context)(struct clk_hw *hw);
>>> + void (*restore_context)(struct clk_hw *hw);
>>> unsigned long (*recalc_rate)(struct clk_hw *hw,
>>> unsigned long parent_rate);
>>> long (*round_rate)(struct clk_hw *hw, unsigned long rate,
>>> @@ -394,6 +401,7 @@ struct clk_divider {
>>> u8 flags;
>>> const struct clk_div_table *table;
>>> spinlock_t *lock;
>>> + u32 context;
>>> };
>>>
>>> #define to_clk_divider(_hw) container_of(_hw, struct clk_divider, hw)
>>> @@ -471,6 +479,7 @@ struct clk_mux {
>>> u8 shift;
>>> u8 flags;
>>> spinlock_t *lock;
>>> + u8 saved_parent;
>>> };
>>>
>>> #define to_clk_mux(_hw) container_of(_hw, struct clk_mux, hw)
>>> @@ -912,5 +921,7 @@ struct dentry *clk_debugfs_add_file(struct clk_hw
>>> *hw, char *name, umode_t mode,
>>> void *data, const struct file_operations *fops);
>>> #endif
>>>
>>> +void clk_dflt_restore_context(struct clk_hw *hw);
>>> +
>>> #endif /* CONFIG_COMMON_CLK */
>>> #endif /* CLK_PROVIDER_H */
>>> diff --git a/include/linux/clk.h b/include/linux/clk.h
>>> index 024cd07..d071a65 100644
>>> --- a/include/linux/clk.h
>>> +++ b/include/linux/clk.h
>>> @@ -438,6 +438,23 @@ struct clk *devm_get_clk_from_child(struct
>>> device *dev,
>>> */
>>> struct clk *clk_get_sys(const char *dev_id, const char *con_id);
>>>
>>> +/**
>>> + * clks_save_context - save clock context for poweroff
>>> + *
>>> + * Saves the context of the clock register for powerstates in which the
>>> + * contents of the registers will be lost. Occurs deep within the
>>> suspend
>>> + * code so locking is not necessary.
>>> + */
>>> +int clks_save_context(void);
>>> +
>>> +/**
>>> + * clks_restore_context - restore clock context after poweroff
>>> + *
>>> + * This occurs with all clocks enabled. Occurs deep within the
>>> resume code
>>> + * so locking is not necessary.
>>> + */
>>> +void clks_restore_context(void);
>>> +
>>> #else /* !CONFIG_HAVE_CLK */
>>>
>>> static inline struct clk *clk_get(struct device *dev, const char *id)
>>> @@ -501,6 +518,14 @@ static inline struct clk *clk_get_sys(const char
>>> *dev_id, const char *con_id)
>>> {
>>> return NULL;
>>> }
>>> +
>>> +static inline int clks_save_context(void)
>>> +{
>>> + return 0;
>>> +}
>>> +
>>> +static inline void clks_restore_context(void) {}
>>> +
>>> #endif
>>>
>>> /* clk_prepare_enable helps cases using clk_enable in non-atomic
>>> context. */
>>> diff --git a/include/linux/clk/ti.h b/include/linux/clk/ti.h
>>> index d18da83..f604936 100644
>>> --- a/include/linux/clk/ti.h
>>> +++ b/include/linux/clk/ti.h
>>> @@ -159,6 +159,7 @@ struct clk_hw_omap {
>>> const char *clkdm_name;
>>> struct clockdomain *clkdm;
>>> const struct clk_hw_omap_ops *ops;
>>> + u32 context;
>>> };
>>>
>>> /*
>>> @@ -290,6 +291,11 @@ struct ti_clk_features {
>>>
>>> void ti_clk_setup_features(struct ti_clk_features *features);
>>> const struct ti_clk_features *ti_clk_get_features(void);
>>> +int omap3_noncore_dpll_save_context(struct clk_hw *hw);
>>> +void omap3_noncore_dpll_restore_context(struct clk_hw *hw);
>>> +
>>> +int omap3_core_dpll_save_context(struct clk_hw *hw);
>>> +void omap3_core_dpll_restore_context(struct clk_hw *hw);
>>>
>>> extern const struct clk_hw_omap_ops clkhwops_omap2xxx_dpll;
>>>
>>> --
>>> 1.9.1
>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-clk" in
>>> the body of a message to majordomo@xxxxxxxxxxxxxxx
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