Re: [PATCH V6 14/21] clk: tegra210: Add suspend and resume support

Dmitry Osipenko
2019-07-21T21:38:53Z

21.07.2019 22:40, Sowjanya Komatineni пишет:
> This patch adds support for clk: tegra210: suspend-resume.
>
> All the CAR controller settings are lost on suspend when core
> power goes off.
>
> This patch has implementation for saving and restoring all PLLs
> and clocks context during system suspend and resume to have the
> clocks back to same state for normal operation.
>
> Acked-by: Thierry Reding <treding@nvidia.com>
> Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
> ---
> drivers/clk/tegra/clk-tegra210.c | 68 ++++++++++++++++++++++++++++++++++++++--
> drivers/clk/tegra/clk.c | 14 +++++++++
> drivers/clk/tegra/clk.h | 1 +
> 3 files changed, 80 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/clk/tegra/clk-tegra210.c b/drivers/clk/tegra/clk-tegra210.c
> index 55a88c0824a5..68271873acc1 100644
> --- a/drivers/clk/tegra/clk-tegra210.c
> +++ b/drivers/clk/tegra/clk-tegra210.c
> @@ -9,6 +9,7 @@
> #include <linux/clkdev.h>
> #include <linux/of.h>
> #include <linux/of_address.h>
> +#include <linux/syscore_ops.h>
> #include <linux/delay.h>
> #include <linux/export.h>
> #include <linux/mutex.h>
> @@ -220,11 +221,15 @@
> #define CLK_M_DIVISOR_SHIFT 2
> #define CLK_M_DIVISOR_MASK 0x3
>
> +#define CLK_MASK_ARM 0x44
> +#define MISC_CLK_ENB 0x48
> +
> #define RST_DFLL_DVCO 0x2f4
> #define DVFS_DFLL_RESET_SHIFT 0
>
> #define CLK_RST_CONTROLLER_RST_DEV_Y_SET 0x2a8
> #define CLK_RST_CONTROLLER_RST_DEV_Y_CLR 0x2ac
> +#define CPU_SOFTRST_CTRL 0x380
>
> #define LVL2_CLK_GATE_OVRA 0xf8
> #define LVL2_CLK_GATE_OVRC 0x3a0
> @@ -2825,6 +2830,7 @@ static int tegra210_enable_pllu(void)
> struct tegra_clk_pll_freq_table *fentry;
> struct tegra_clk_pll pllu;
> u32 reg;
> + int ret;
>
> for (fentry = pll_u_freq_table; fentry->input_rate; fentry++) {
> if (fentry->input_rate == pll_ref_freq)
> @@ -2853,9 +2859,8 @@ static int tegra210_enable_pllu(void)
> reg |= PLL_ENABLE;
> writel(reg, clk_base + PLLU_BASE);
>
> - readl_relaxed_poll_timeout_atomic(clk_base + PLLU_BASE, reg,
> - reg & PLL_BASE_LOCK, 2, 1000);
> - if (!(reg & PLL_BASE_LOCK)) {
> + ret = tegra210_wait_for_mask(&pllu, PLLU_BASE, PLL_BASE_LOCK);
> + if (ret) {

Why this is needed? Was there a bug?

> pr_err("Timed out waiting for PLL_U to lock\n");
> return -ETIMEDOUT;
> }
> @@ -3288,6 +3293,56 @@ static void tegra210_disable_cpu_clock(u32 cpu)
> }
>
> #ifdef CONFIG_PM_SLEEP
> +#define car_readl(_base, _off) readl_relaxed(clk_base + (_base) + ((_off) * 4))
> +#define car_writel(_val, _base, _off) \
> + writel_relaxed(_val, clk_base + (_base) + ((_off) * 4))
> +
> +static u32 spare_reg_ctx, misc_clk_enb_ctx, clk_msk_arm_ctx;
> +static u32 cpu_softrst_ctx[3];
> +
> +static int tegra210_clk_suspend(void)
> +{
> + unsigned int i;
> +
> + clk_save_context();
> +
> + /*
> + * save the bootloader configured clock registers SPARE_REG0,
> + * MISC_CLK_ENB, CLK_MASK_ARM, CPU_SOFTRST_CTRL

Nit: Start all multi-line comments with a capital letter and put dot in
the end of sentence.

> + */
> + spare_reg_ctx = readl_relaxed(clk_base + SPARE_REG0);
> + misc_clk_enb_ctx = readl_relaxed(clk_base + MISC_CLK_ENB);
> + clk_msk_arm_ctx = readl_relaxed(clk_base + CLK_MASK_ARM);
> +
> + for (i = 0; i < ARRAY_SIZE(cpu_softrst_ctx); i++)
> + cpu_softrst_ctx[i] = car_readl(CPU_SOFTRST_CTRL, i);
> +
> + return 0;
> +}
> +
> +static void tegra210_clk_resume(void)
> +{
> + unsigned int i;
> +
> + tegra_clk_osc_resume(clk_base);
> +
> + /*
> + * restore the bootloader configured clock registers SPARE_REG0,
> + * MISC_CLK_ENB, CLK_MASK_ARM, CPU_SOFTRST_CTRL from saved context.

Same here.

> + */
> + writel_relaxed(spare_reg_ctx, clk_base + SPARE_REG0);
> + writel_relaxed(misc_clk_enb_ctx, clk_base + MISC_CLK_ENB);
> + writel_relaxed(clk_msk_arm_ctx, clk_base + CLK_MASK_ARM);
> +
> + for (i = 0; i < ARRAY_SIZE(cpu_softrst_ctx); i++)
> + car_writel(cpu_softrst_ctx[i], CPU_SOFTRST_CTRL, i);
> +
> + fence_udelay(5, clk_base);
> +
> + tegra210_init_pllu();
> + clk_restore_context();
> +}
> +
> static void tegra210_cpu_clock_suspend(void)
> {
> /* switch coresite to clk_m, save off original source */
> @@ -3303,6 +3358,11 @@ static void tegra210_cpu_clock_resume(void)
> }
> #endif
>
> +static struct syscore_ops tegra_clk_syscore_ops = {
> + .suspend = tegra210_clk_suspend,
> + .resume = tegra210_clk_resume,
> +};
> +
> static struct tegra_cpu_car_ops tegra210_cpu_car_ops = {
> .wait_for_reset = tegra210_wait_cpu_in_reset,
> .disable_clock = tegra210_disable_cpu_clock,
> @@ -3587,5 +3647,7 @@ static void __init tegra210_clock_init(struct device_node *np)
> tegra210_mbist_clk_init();
>
> tegra_cpu_car_ops = &tegra210_cpu_car_ops;
> +
> + register_syscore_ops(&tegra_clk_syscore_ops);
> }
> CLK_OF_DECLARE(tegra210, "nvidia,tegra210-car", tegra210_clock_init);
> diff --git a/drivers/clk/tegra/clk.c b/drivers/clk/tegra/clk.c
> index 573e3c967ae1..eb08047fd02f 100644
> --- a/drivers/clk/tegra/clk.c
> +++ b/drivers/clk/tegra/clk.c
> @@ -23,6 +23,7 @@
> #define CLK_OUT_ENB_W 0x364
> #define CLK_OUT_ENB_X 0x280
> #define CLK_OUT_ENB_Y 0x298
> +#define CLK_ENB_PLLP_OUT_CPU BIT(31)
> #define CLK_OUT_ENB_SET_L 0x320
> #define CLK_OUT_ENB_CLR_L 0x324
> #define CLK_OUT_ENB_SET_H 0x328
> @@ -199,6 +200,19 @@ const struct tegra_clk_periph_regs *get_reg_bank(int clkid)
> }
> }
>
> +void tegra_clk_set_pllp_out_cpu(bool enable)
> +{
> + u32 val;
> +
> + val = readl_relaxed(clk_base + CLK_OUT_ENB_Y);
> + if (enable)
> + val |= CLK_ENB_PLLP_OUT_CPU;
> + else
> + val &= ~CLK_ENB_PLLP_OUT_CPU;
> +
> + writel_relaxed(val, clk_base + CLK_OUT_ENB_Y);
> +}
> +
> 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 562a3ee2d537..0ffa763c755b 100644
> --- a/drivers/clk/tegra/clk.h
> +++ b/drivers/clk/tegra/clk.h
> @@ -863,6 +863,7 @@ int div_frac_get(unsigned long rate, unsigned parent_rate, u8 width,
> u8 frac_width, u8 flags);
> void tegra_clk_sync_state_pll(struct clk_hw *hw);
> void tegra_clk_osc_resume(void __iomem *clk_base);
> +void tegra_clk_set_pllp_out_cpu(bool enable);
>
> /* Combined read fence with delay */
> #define fence_udelay(delay, reg) \
>