[PATCH] cpufreq: add suspend/resume support in Armada 37xx DVFS driver

[Viresh Kumar]

On 21-04-18, 16:19, Miquel Raynal wrote:
> Add suspend/resume hooks in Armada 37xx DVFS driver to handle S2RAM
> operations. As there is currently no 'driver' structure, create one
> to store both the regmap and the register values during suspend
> operation.
> 
> A syscore_ops is used to export the suspend/resume hooks.
> 
> Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>
> ---
>  drivers/cpufreq/armada-37xx-cpufreq.c | 73 ++++++++++++++++++++++++++++++++++-
>  1 file changed, 71 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cpufreq/armada-37xx-cpufreq.c b/drivers/cpufreq/armada-37xx-cpufreq.c
> index 72a2975499db..9c9c3673cbbe 100644
> --- a/drivers/cpufreq/armada-37xx-cpufreq.c
> +++ b/drivers/cpufreq/armada-37xx-cpufreq.c
> @@ -22,6 +22,7 @@
>  #include <linux/pm_opp.h>
>  #include <linux/regmap.h>
>  #include <linux/slab.h>
> +#include <linux/syscore_ops.h>
>  
>  /* Power management in North Bridge register set */
>  #define ARMADA_37XX_NB_L0L1	0x18
> @@ -56,6 +57,18 @@
>   */
>  #define LOAD_LEVEL_NR	4
>  
> +#if defined(CONFIG_PM)
> +struct armada37xx_cpufreq_state {
> +	struct regmap *regmap;
> +	u32 nb_l0l1;
> +	u32 nb_l2l3;
> +	u32 nb_dyn_mod;
> +	u32 nb_cpu_load;
> +};
> +
> +static struct armada37xx_cpufreq_state *armada37xx_cpufreq_state;
> +#endif /* CONFIG_PM */
> +
>  struct armada_37xx_dvfs {
>  	u32 cpu_freq_max;
>  	u8 divider[LOAD_LEVEL_NR];
> @@ -136,7 +149,7 @@ static void __init armada37xx_cpufreq_dvfs_setup(struct regmap *base,
>  	clk_set_parent(clk, parent);
>  }
>  
> -static void __init armada37xx_cpufreq_disable_dvfs(struct regmap *base)
> +static void armada37xx_cpufreq_disable_dvfs(struct regmap *base)
>  {
>  	unsigned int reg = ARMADA_37XX_NB_DYN_MOD,
>  		mask = ARMADA_37XX_NB_DFS_EN;
> @@ -162,6 +175,46 @@ static void __init armada37xx_cpufreq_enable_dvfs(struct regmap *base)
>  	regmap_update_bits(base, reg, mask, mask);
>  }
>  
> +#if defined(CONFIG_PM)
> +static int armada37xx_cpufreq_suspend(void)
> +{
> +	struct armada37xx_cpufreq_state *state = armada37xx_cpufreq_state;
> +
> +	regmap_read(state->regmap, ARMADA_37XX_NB_L0L1, &state->nb_l0l1);
> +	regmap_read(state->regmap, ARMADA_37XX_NB_L2L3, &state->nb_l2l3);
> +	regmap_read(state->regmap, ARMADA_37XX_NB_CPU_LOAD,
> +		    &state->nb_cpu_load);
> +	regmap_read(state->regmap, ARMADA_37XX_NB_DYN_MOD, &state->nb_dyn_mod);
> +
> +	return 0;
> +}
> +
> +static void armada37xx_cpufreq_resume(void)
> +{
> +	struct armada37xx_cpufreq_state *state = armada37xx_cpufreq_state;
> +
> +	/* Ensure DVFS is disabled otherwise the following registers are RO */
> +	armada37xx_cpufreq_disable_dvfs(state->regmap);
> +
> +	regmap_write(state->regmap, ARMADA_37XX_NB_L0L1, state->nb_l0l1);
> +	regmap_write(state->regmap, ARMADA_37XX_NB_L2L3, state->nb_l2l3);
> +	regmap_write(state->regmap, ARMADA_37XX_NB_CPU_LOAD,
> +		     state->nb_cpu_load);
> +
> +	/*
> +	 * NB_DYN_MOD register is the one that actually enable back DVFS if it
> +	 * was enabled before the suspend operation. This must be done last
> +	 * otherwise other registers are not writable.
> +	 */
> +	regmap_write(state->regmap, ARMADA_37XX_NB_DYN_MOD, state->nb_dyn_mod);
> +}
> +
> +static struct syscore_ops armada37xx_cpufreq_syscore_pm_ops = {
> +	.suspend = armada37xx_cpufreq_suspend,
> +	.resume = armada37xx_cpufreq_resume,
> +};

And why can't you use the suspend/resume callbacks present in the struct
cpufreq_driver ?

-- 
viresh