Re: [PATCH V5 06/18] clk: tegra: Save and restore CPU and System clocks context

[Dmitry Osipenko]

28.06.2019 5:12, Sowjanya Komatineni ÐÐÑÐÑ:
> During system suspend state, core power goes off and looses all the
> CAR controller register settings.
> 
> This patch creates APIs for saving and restoring the context of Tegra
> CPUG, CPULP and SCLK.
> 
> CPU and System clock context includes
> - CPUG, CPULP, and SCLK burst policy settings for clock sourcea of all
>   their normal states.
> - SCLK divisor and System clock rate for restoring SCLK, AHB and APB
>   rates on resume.
> - OSC_DIV settings which are used as reference clock input to some PLLs.
> - SPARE_REG and CLK_MASK settings.
> 
> These APIs are used in Tegra210 clock driver during suspend and resume
> operation.
> 
> Acked-by: Thierry Reding <treding@xxxxxxxxxx>
> Signed-off-by: Sowjanya Komatineni <skomatineni@xxxxxxxxxx>
> ---
>  drivers/clk/tegra/clk-tegra-super-gen4.c |  4 --
>  drivers/clk/tegra/clk.c                  | 80 ++++++++++++++++++++++++++++++++
>  drivers/clk/tegra/clk.h                  | 14 ++++++
>  3 files changed, 94 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/clk/tegra/clk-tegra-super-gen4.c b/drivers/clk/tegra/clk-tegra-super-gen4.c
> index cdfe7c9697e1..ed69ec4d883e 100644
> --- a/drivers/clk/tegra/clk-tegra-super-gen4.c
> +++ b/drivers/clk/tegra/clk-tegra-super-gen4.c
> @@ -19,10 +19,6 @@
>  #define PLLX_MISC2 0x514
>  #define PLLX_MISC3 0x518
>  
> -#define CCLKG_BURST_POLICY 0x368
> -#define CCLKLP_BURST_POLICY 0x370
> -#define SCLK_BURST_POLICY 0x028
> -#define SYSTEM_CLK_RATE 0x030
>  #define SCLK_DIVIDER 0x2c
>  
>  static DEFINE_SPINLOCK(sysrate_lock);
> diff --git a/drivers/clk/tegra/clk.c b/drivers/clk/tegra/clk.c
> index 573e3c967ae1..9e863362d2bf 100644
> --- a/drivers/clk/tegra/clk.c
> +++ b/drivers/clk/tegra/clk.c
> @@ -70,6 +70,12 @@ static struct clk **clks;
>  static int clk_num;
>  static struct clk_onecell_data clk_data;
>  
> +static u32 cclkg_burst_policy_ctx[2];
> +static u32 cclklp_burst_policy_ctx[2];
> +static u32 sclk_burst_policy_ctx[2];
> +static u32 sys_clk_divisor_ctx, system_rate_ctx;
> +static u32 spare_ctx, misc_clk_enb_ctx, clk_arm_ctx;
> +
>  /* Handlers for SoC-specific reset lines */
>  static int (*special_reset_assert)(unsigned long);
>  static int (*special_reset_deassert)(unsigned long);
> @@ -199,6 +205,80 @@ const struct tegra_clk_periph_regs *get_reg_bank(int clkid)
>  	}
>  }
>  
> +void tegra_cclkg_burst_policy_save_context(void)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < BURST_POLICY_REG_SIZE; i++)
> +		cclkg_burst_policy_ctx[i] = readl_relaxed(clk_base +
> +							  CCLKG_BURST_POLICY +
> +							  (i * 4));
> +}
> +
> +void tegra_cclkg_burst_policy_restore_context(void)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < BURST_POLICY_REG_SIZE; i++)
> +		writel_relaxed(cclkg_burst_policy_ctx[i],
> +			       clk_base + CCLKG_BURST_POLICY + (i * 4));
> +
> +	fence_udelay(2, clk_base);
> +}
> +
> +void tegra_sclk_cclklp_burst_policy_save_context(void)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < BURST_POLICY_REG_SIZE; i++) {
> +		cclklp_burst_policy_ctx[i] = readl_relaxed(clk_base +
> +							  CCLKLP_BURST_POLICY +
> +							  (i * 4));
> +
> +		sclk_burst_policy_ctx[i] = readl_relaxed(clk_base +
> +							  SCLK_BURST_POLICY +
> +							  (i * 4));
> +	}
> +
> +	sys_clk_divisor_ctx = readl_relaxed(clk_base + SYS_CLK_DIV);
> +	system_rate_ctx = readl_relaxed(clk_base + SYSTEM_CLK_RATE);
> +	spare_ctx = readl_relaxed(clk_base + SPARE_REG0);
> +	misc_clk_enb_ctx = readl_relaxed(clk_base + MISC_CLK_ENB);
> +	clk_arm_ctx = readl_relaxed(clk_base + CLK_MASK_ARM);
> +}
> +
> +void tegra_sclk_cpulp_burst_policy_restore_context(void)
> +{
> +	unsigned int i;
> +	u32 val;
> +
> +	/*
> +	 * resume SCLK and CPULP clocks
> +	 * for SCLk, set safe dividers values first and then restore source
> +	 * and dividers
> +	 */
> +
> +	writel_relaxed(0x1, clk_base + SYSTEM_CLK_RATE);
> +	val = readl_relaxed(clk_base + SYS_CLK_DIV);
> +	if (val < sys_clk_divisor_ctx)
> +		writel_relaxed(sys_clk_divisor_ctx, clk_base + SYS_CLK_DIV);
> +
> +	fence_udelay(2, clk_base);
> +
> +	for (i = 0; i < BURST_POLICY_REG_SIZE; i++) {
> +		writel_relaxed(cclklp_burst_policy_ctx[i],
> +			       clk_base + CCLKLP_BURST_POLICY + (i * 4));
> +		writel_relaxed(sclk_burst_policy_ctx[i],
> +			       clk_base + SCLK_BURST_POLICY + (i * 4));
> +	}
> +
> +	writel_relaxed(sys_clk_divisor_ctx, clk_base + SYS_CLK_DIV);
> +	writel_relaxed(system_rate_ctx, clk_base + SYSTEM_CLK_RATE);
> +	writel_relaxed(spare_ctx, clk_base + SPARE_REG0);
> +	writel_relaxed(misc_clk_enb_ctx, clk_base + MISC_CLK_ENB);
> +	writel_relaxed(clk_arm_ctx, clk_base + CLK_MASK_ARM);
> +}
> +
>  struct clk ** __init tegra_clk_init(void __iomem *regs, int num, int banks)
>  {
>  	clk_base = regs;
> diff --git a/drivers/clk/tegra/clk.h b/drivers/clk/tegra/clk.h
> index 8532f5150091..c66b0a73bb01 100644
> --- a/drivers/clk/tegra/clk.h
> +++ b/drivers/clk/tegra/clk.h
> @@ -10,6 +10,16 @@
>  #include <linux/clkdev.h>
>  #include <linux/delay.h>
>  
> +#define SCLK_BURST_POLICY	0x28
> +#define SYSTEM_CLK_RATE		0x30
> +#define CLK_MASK_ARM		0x44
> +#define MISC_CLK_ENB		0x48
> +#define CCLKG_BURST_POLICY	0x368
> +#define CCLKLP_BURST_POLICY	0x370
> +#define SYS_CLK_DIV		0x400
> +#define SPARE_REG0		0x55c
> +#define BURST_POLICY_REG_SIZE	2

"clk-tegra30.c",  "clk-tegra114.c" and "clk-tegra124.c" also define the
CCLKG_BURST_POLICY .. apparently you haven't tried to compile ARM32 kernel because I
assume that compile should bark at the re-definitions.