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

Dmitry Osipenko
2019-06-29T13:33:12Z

28.06.2019 5:12, Sowjanya Komatineni пишет:
> 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@nvidia.com>
> Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
> ---
> 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);

Why fence_udelay was needed above and not needed here?

> +}