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

[Sowjanya Komatineni <skomatineni@nvidia.com>]

On 7/21/19 11:10 PM, Dmitry Osipenko wrote:
> 22.07.2019 1:45, Sowjanya Komatineni пишет:
>> On 7/21/19 2:38 PM, Dmitry Osipenko wrote:
>>> 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?
>>>
>> during resume pllu init is needed and to use same terga210_init_pllu,
>> poll_timeout_atomic can't be used as its ony for atomic context.
>>
>> So changed to use wait_for_mask which should work in both cases.
> Atomic variant could be used from any context, not sure what do you
> mean. The 'atomic' part only means that function won't cause scheduling
> and that's it.

Sorry, replied incorrect. readx_poll_timeout_atomic uses ktime_get() and 
during resume timekeeping suspend/resume happens later than clock 
suspend/resume. So using tegra210_wait_for_mask.

both timekeeping and clk-tegra210 drivers are registered as syscore but 
not ordered.

>>>>            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)    \
>>>>