linux-kernel - Re: [PATCH V3 08/17] clk: tegra: add support for peripheral clock suspend and resume

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Message-ID: <20190618115055.GK28892@ulmo>
Date:   Tue, 18 Jun 2019 13:50:55 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Sowjanya Komatineni <skomatineni@...dia.com>
Cc:     jonathanh@...dia.com, tglx@...utronix.de, jason@...edaemon.net,
        marc.zyngier@....com, linus.walleij@...aro.org, stefan@...er.ch,
        mark.rutland@....com, 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, digetx@...il.com,
        devicetree@...r.kernel.org
Subject: Re: [PATCH V3 08/17] clk: tegra: add support for peripheral clock
 suspend and resume

On Tue, Jun 18, 2019 at 12:46:22AM -0700, Sowjanya Komatineni wrote:
> This patch creates APIs to save and restore the state of all
> peripheral clocks reset and enables.
> 
> These APIs are invoked by Tegra210 clock driver during suspend and
> resume to save the peripheral clocks state before suspend and to
> restore them on resume.
> 
> Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
> ---
>  drivers/clk/tegra/clk.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++-
>  drivers/clk/tegra/clk.h |  3 +++
>  2 files changed, 72 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/tegra/clk.c b/drivers/clk/tegra/clk.c
> index 26690663157a..bd3b46c5f941 100644
> --- a/drivers/clk/tegra/clk.c
> +++ b/drivers/clk/tegra/clk.c
> @@ -70,6 +70,7 @@ static struct clk **clks;
>  static int clk_num;
>  static struct clk_onecell_data clk_data;
>  
> +static u32 *periph_ctx;
>  static u32 cclkg_burst_policy_ctx[2];
>  static u32 cclklp_burst_policy_ctx[2];
>  static u32 sclk_burst_policy_ctx[2];
> @@ -279,6 +280,63 @@ void tegra_sclk_cpulp_burst_policy_restore_context(void)
>  	writel_relaxed(clk_arm_ctx, clk_base + CLK_MASK_ARM);
>  }
>  
> +void tegra_clk_periph_suspend(void __iomem *clk_base)
> +{
> +	int i, idx;

Can be unsigned int. Same for below.

> +
> +	idx = 0;
> +	for (i = 0; i < periph_banks; i++, idx++)
> +		periph_ctx[idx] =
> +			readl_relaxed(clk_base + periph_regs[i].rst_reg);
> +
> +	for (i = 0; i < periph_banks; i++, idx++)
> +		periph_ctx[idx] =
> +			readl_relaxed(clk_base + periph_regs[i].enb_reg);
> +}
> +
> +void tegra_clk_periph_force_on(u32 *clks_on, int count, void __iomem *clk_base)

count can also be unsigned int.

> +{
> +	int i;
> +
> +	WARN_ON(count != periph_banks);
> +
> +	for (i = 0; i < count; i++)
> +		writel_relaxed(clks_on[i], clk_base + periph_regs[i].enb_reg);
> +}
> +
> +void tegra_clk_periph_resume(void __iomem *clk_base)
> +{
> +	int i, idx;
> +
> +	idx = 0;
> +	for (i = 0; i < periph_banks; i++, idx++)
> +		writel_relaxed(periph_ctx[idx],
> +			       clk_base + periph_regs[i].rst_reg);
> +
> +	/* ensure all resets have propagated */
> +	fence_udelay(2, clk_base);
> +	tegra_read_chipid();
> +
> +	for (i = 0; i < periph_banks; i++, idx++)
> +		writel_relaxed(periph_ctx[idx],
> +			       clk_base + periph_regs[i].enb_reg);
> +
> +	/* ensure all enables have propagated */
> +	fence_udelay(2, clk_base);
> +	tegra_read_chipid();
> +}
> +
> +static int tegra_clk_suspend_ctx_init(int banks)
> +{
> +	int err = 0;
> +
> +	periph_ctx = kcalloc(2 * banks, sizeof(*periph_ctx), GFP_KERNEL);
> +	if (!periph_ctx)
> +		err = -ENOMEM;
> +
> +	return err;
> +}
> +
>  struct clk ** __init tegra_clk_init(void __iomem *regs, int num, int banks)
>  {
>  	clk_base = regs;
> @@ -295,11 +353,21 @@ struct clk ** __init tegra_clk_init(void __iomem *regs, int num, int banks)
>  	periph_banks = banks;
>  
>  	clks = kcalloc(num, sizeof(struct clk *), GFP_KERNEL);
> -	if (!clks)
> +	if (!clks) {
>  		kfree(periph_clk_enb_refcnt);
> +		return NULL;
> +	}
>  
>  	clk_num = num;
>  
> +	if (IS_ENABLED(CONFIG_PM_SLEEP)) {
> +		if (tegra_clk_suspend_ctx_init(banks)) {
> +			kfree(periph_clk_enb_refcnt);
> +			kfree(clks);
> +			return NULL;
> +		}
> +	}
> +
>  	return clks;
>  }
>  
> diff --git a/drivers/clk/tegra/clk.h b/drivers/clk/tegra/clk.h
> index c8f8a23096e2..a354cacae5a6 100644
> --- a/drivers/clk/tegra/clk.h
> +++ b/drivers/clk/tegra/clk.h
> @@ -853,6 +853,9 @@ void tegra_cclkg_burst_policy_save_context(void);
>  void tegra_cclkg_burst_policy_restore_context(void);
>  void tegra_sclk_cclklp_burst_policy_save_context(void);
>  void tegra_sclk_cpulp_burst_policy_restore_context(void);
> +void tegra_clk_periph_suspend(void __iomem *clk_base);
> +void tegra_clk_periph_resume(void __iomem *clk_base);
> +void tegra_clk_periph_force_on(u32 *clks_on, int count, void __iomem *clk_base);
>  
>  /* Combined read fence with delay */
>  #define fence_udelay(delay, reg)	\

Other than the nitpicks, looks good:

Acked-by: Thierry Reding <treding@...dia.com>

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