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Subject: Re: [PATCH v4 06/19] soc: tegra: Add Tegra PMC clock registrations
 into PMC driver
To:     Sowjanya Komatineni <skomatineni@nvidia.com>,
        thierry.reding@gmail.com, jonathanh@nvidia.com,
        mperttunen@nvidia.com, gregkh@linuxfoundation.org,
        sboyd@kernel.org, robh+dt@kernel.org, mark.rutland@arm.com
Cc:     pdeschrijver@nvidia.com, pgaikwad@nvidia.com, spujar@nvidia.com,
        josephl@nvidia.com, daniel.lezcano@linaro.org,
        mmaddireddy@nvidia.com, markz@nvidia.com,
        devicetree@vger.kernel.org, linux-clk@vger.kernel.org,
        linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org
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 <c5bb3c25-1fae-3ca9-6bf3-c3d66be20e19@nvidia.com>
 <664f1a41-d539-36e8-092b-11d7e4555108@nvidia.com>
From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <31020f6b-97bf-eb48-1150-0355c868eafc@gmail.com>
Date:   Fri, 20 Dec 2019 04:39:43 +0300
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20.12.2019 04:21, Sowjanya Komatineni пишет:
> 
> On 12/18/19 4:41 PM, Sowjanya Komatineni wrote:
>>
>> On 12/18/19 1:44 PM, Dmitry Osipenko wrote:
>>> 18.12.2019 11:35, Dmitry Osipenko пишет:
>>>> 18.12.2019 11:30, Dmitry Osipenko пишет:
>>>>> 17.12.2019 23:03, Sowjanya Komatineni пишет:
>>>>>> Tegra PMC has clk_out_1, clk_out_2, and clk_out_3 clocks and
>>>>>> currently
>>>>>> these PMC clocks are registered by Tegra clock driver with each
>>>>>> clock as
>>>>>> separate mux and gate clocks using clk_register_mux and
>>>>>> clk_register_gate
>>>>>> by passing PMC base address and register offsets and PMC
>>>>>> programming for
>>>>>> these clocks happens through direct PMC access by the clock driver.
>>>>>>
>>>>>> With this, when PMC is in secure mode any direct PMC access from the
>>>>>> non-secure world does not go through and these clocks will not be
>>>>>> functional.
>>>>>>
>>>>>> This patch adds these PMC clocks registration to pmc driver with
>>>>>> PMC as
>>>>>> a clock provider and registers each clock as single clock.
>>>>>>
>>>>>> clk_ops callback implementations for these clocks uses
>>>>>> tegra_pmc_readl and
>>>>>> tegra_pmc_writel which supports PMC programming in both secure
>>>>>> mode and
>>>>>> non-secure mode.
>>>>>>
>>>>>> Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
>>>>>> ---
>>>>>>   drivers/soc/tegra/pmc.c | 248
>>>>>> ++++++++++++++++++++++++++++++++++++++++++++++++
>>>>>>   1 file changed, 248 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
>>>>>> index ea0e11a09c12..6d65194a6e71 100644
>>>>>> --- a/drivers/soc/tegra/pmc.c
>>>>>> +++ b/drivers/soc/tegra/pmc.c
>>>>>> @@ -13,6 +13,9 @@
>>>>>>     #include <linux/arm-smccc.h>
>>>>>>   #include <linux/clk.h>
>>>>>> +#include <linux/clk-provider.h>
>>>>>> +#include <linux/clkdev.h>
>>>>>> +#include <linux/clk/clk-conf.h>
>>>>>>   #include <linux/clk/tegra.h>
>>>>>>   #include <linux/debugfs.h>
>>>>>>   #include <linux/delay.h>
>>>>>> @@ -48,6 +51,7 @@
>>>>>>   #include <dt-bindings/pinctrl/pinctrl-tegra-io-pad.h>
>>>>>>   #include <dt-bindings/gpio/tegra186-gpio.h>
>>>>>>   #include <dt-bindings/gpio/tegra194-gpio.h>
>>>>>> +#include <dt-bindings/soc/tegra-pmc.h>
>>>>>>     #define PMC_CNTRL            0x0
>>>>>>   #define  PMC_CNTRL_INTR_POLARITY    BIT(17) /* inverts INTR
>>>>>> polarity */
>>>>>> @@ -100,6 +104,7 @@
>>>>>>   #define PMC_WAKE2_STATUS        0x168
>>>>>>   #define PMC_SW_WAKE2_STATUS        0x16c
>>>>>>   +#define PMC_CLK_OUT_CNTRL        0x1a8
>>>>>>   #define PMC_SENSOR_CTRL            0x1b0
>>>>>>   #define  PMC_SENSOR_CTRL_SCRATCH_WRITE    BIT(2)
>>>>>>   #define  PMC_SENSOR_CTRL_ENABLE_RST    BIT(1)
>>>>>> @@ -155,6 +160,64 @@
>>>>>>   #define  TEGRA_SMC_PMC_READ    0xaa
>>>>>>   #define  TEGRA_SMC_PMC_WRITE    0xbb
>>>>>>   +struct pmc_clk {
>>>>>> +    struct clk_hw    hw;
>>>>>> +    unsigned long    offs;
>>>>>> +    u32        mux_mask;
>>>>>> +    u32        mux_shift;
>>>>>> +    u32        gate_shift;
>>>>>> +};
>>>>>> +
>>>>>> +#define to_pmc_clk(_hw) container_of(_hw, struct pmc_clk, hw)
>>>>>> +
>>>>>> +struct pmc_clk_init_data {
>>>>>> +    char *name;
>>>>>> +    const char *const *parents;
>>>>>> +    int num_parents;
>>>>>> +    int clk_id;
>>>>>> +    u8 mux_shift;
>>>>>> +    u8 gate_shift;
>>>>>> +};
>>>>>> +
>>>>>> +static const char * const clk_out1_parents[] = { "osc", "osc_div2",
>>>>>> +    "osc_div4", "extern1",
>>>>>> +};
>>>>>> +
>>>>>> +static const char * const clk_out2_parents[] = { "osc", "osc_div2",
>>>>>> +    "osc_div4", "extern2",
>>>>>> +};
>>>>>> +
>>>>>> +static const char * const clk_out3_parents[] = { "osc", "osc_div2",
>>>>>> +    "osc_div4", "extern3",
>>>>>> +};
>>>>>> +
>>>>>> +static const struct pmc_clk_init_data tegra_pmc_clks_data[] = {
>>>>>> +    {
>>>>>> +        .name = "clk_out_1",
>>>>>> +        .parents = clk_out1_parents,
>>>>>> +        .num_parents = ARRAY_SIZE(clk_out1_parents),
>>>>>> +        .clk_id = TEGRA_PMC_CLK_OUT_1,
>>>>>> +        .mux_shift = 6,
>>>>>> +        .gate_shift = 2,
>>>>> I'd replace these with a single .shift, given that mux_shift =
>>>>> gate_shift + 4 for all clocks.
>>>>>
>>>>>> +    },
>>>>>> +    {
>>>>>> +        .name = "clk_out_2",
>>>>>> +        .parents = clk_out2_parents,
>>>>>> +        .num_parents = ARRAY_SIZE(clk_out2_parents),
>>>>>> +        .clk_id = TEGRA_PMC_CLK_OUT_2,
>>>>>> +        .mux_shift = 14,
>>>>>> +        .gate_shift = 10,
>>>>>> +    },
>>>>>> +    {
>>>>>> +        .name = "clk_out_3",
>>>>>> +        .parents = clk_out3_parents,
>>>>>> +        .num_parents = ARRAY_SIZE(clk_out3_parents),
>>>>>> +        .clk_id = TEGRA_PMC_CLK_OUT_3,
>>>>>> +        .mux_shift = 22,
>>>>>> +        .gate_shift = 18,
>>>>>> +    },
>>>>>> +};
>>>>>> +
>>>>>>   struct tegra_powergate {
>>>>>>       struct generic_pm_domain genpd;
>>>>>>       struct tegra_pmc *pmc;
>>>>>> @@ -254,6 +317,9 @@ struct tegra_pmc_soc {
>>>>>>        */
>>>>>>       const struct tegra_wake_event *wake_events;
>>>>>>       unsigned int num_wake_events;
>>>>>> +
>>>>>> +    const struct pmc_clk_init_data *pmc_clks_data;
>>>>>> +    unsigned int num_pmc_clks;
>>>>>>   };
>>>>>>     static const char * const tegra186_reset_sources[] = {
>>>>>> @@ -2163,6 +2229,173 @@ static int tegra_pmc_clk_notify_cb(struct
>>>>>> notifier_block *nb,
>>>>>>       return NOTIFY_OK;
>>>>>>   }
>>>>>>   +static void pmc_clk_fence_udelay(u32 offset)
>>>>>> +{
>>>>>> +    tegra_pmc_readl(pmc, offset);
>>>>>> +    /* pmc clk propagation delay 2 us */
>>>>>> +    udelay(2);
>>>>>> +}
>>>>>> +
>>>>>> +static u8 pmc_clk_mux_get_parent(struct clk_hw *hw)
>>>>>> +{
>>>>>> +    struct pmc_clk *clk = to_pmc_clk(hw);
>>>>>> +    u32 val;
>>>>>> +
>>>>>> +    val = tegra_pmc_readl(pmc, clk->offs) >> clk->mux_shift;
>>>>>> +    val &= clk->mux_mask;
>>>>>> +
>>>>>> +    return val;
>>>>>> +}
>>>>>> +
>>>>>> +static int pmc_clk_mux_set_parent(struct clk_hw *hw, u8 index)
>>>>>> +{
>>>>>> +    struct pmc_clk *clk = to_pmc_clk(hw);
>>>>>> +    u32 val;
>>>>>> +
>>>>>> +    val = tegra_pmc_readl(pmc, clk->offs);
>>>>>> +    val &= ~(clk->mux_mask << clk->mux_shift);
>>>>>> +    val |= index << clk->mux_shift;
>>>>>> +    tegra_pmc_writel(pmc, val, clk->offs);
>>>>>> +    pmc_clk_fence_udelay(clk->offs);

Is this fencing applies only to clock changes or maybe it won't hurt to
move it into tegra_pmc_writel()?

>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static int pmc_clk_is_enabled(struct clk_hw *hw)
>>>>>> +{
>>>>>> +    struct pmc_clk *clk = to_pmc_clk(hw);
>>>>>> +
>>>>>> +    return tegra_pmc_readl(pmc, clk->offs) & BIT(clk->gate_shift)
>>>>>> ? 1 : 0;
>>>>>> +}
>>>>>> +
>>>>>> +static void pmc_clk_set_state(unsigned long offs, u32 shift, int
>>>>>> state)
>>>>>> +{
>>>>>> +    u32 val;
>>>>>> +
>>>>>> +    val = tegra_pmc_readl(pmc, offs);
>>>>>> +    val = state ? (val | BIT(shift)) : (val & ~BIT(shift));
>>>>>> +    tegra_pmc_writel(pmc, val, offs);
>>>>>> +    pmc_clk_fence_udelay(offs);
>>>>>> +}
>>>>>> +
>>>>>> +static int pmc_clk_enable(struct clk_hw *hw)
>>>>>> +{
>>>>>> +    struct pmc_clk *clk = to_pmc_clk(hw);
>>>>>> +
>>>>>> +    pmc_clk_set_state(clk->offs, clk->gate_shift, 1);
>>>>>> +
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static void pmc_clk_disable(struct clk_hw *hw)
>>>>>> +{
>>>>>> +    struct pmc_clk *clk = to_pmc_clk(hw);
>>>>>> +
>>>>>> +    pmc_clk_set_state(clk->offs, clk->gate_shift, 0);
>>>>>> +}
>>>>>> +
>>>>>> +static const struct clk_ops pmc_clk_ops = {
>>>>>> +    .get_parent = pmc_clk_mux_get_parent,
>>>>>> +    .set_parent = pmc_clk_mux_set_parent,
>>>>>> +    .determine_rate = __clk_mux_determine_rate,
>>>>>> +    .is_enabled = pmc_clk_is_enabled,
>>>>>> +    .enable = pmc_clk_enable,
>>>>>> +    .disable = pmc_clk_disable,
>>>>>> +};
>>>>>> +
>>>>>> +static struct clk *
>>>>>> +tegra_pmc_clk_out_register(const struct pmc_clk_init_data *data,
>>>>>> +               unsigned long offset)
>>>>>> +{
>>>>>> +    struct clk_init_data init;
>>>>>> +    struct pmc_clk *pmc_clk;
>>>>>> +
>>>>>> +    pmc_clk = kzalloc(sizeof(*pmc_clk), GFP_KERNEL);
>>>>>> +    if (!pmc_clk)
>>>>>> +        return ERR_PTR(-ENOMEM);
>>>>>> +
>>>>>> +    init.name = data->name;
>>>>>> +    init.ops = &pmc_clk_ops;
>>>>>> +    init.parent_names = data->parents;
>>>>>> +    init.num_parents = data->num_parents;
>>>>>> +    init.flags = CLK_SET_RATE_NO_REPARENT | CLK_SET_RATE_PARENT |
>>>>>> +             CLK_SET_PARENT_GATE;
>>>>>> +
>>>>>> +    pmc_clk->hw.init = &init;
>>>>>> +    pmc_clk->offs = offset;
>>>>>> +    pmc_clk->mux_mask = 3;
>>>>> If mux_mask is a constant value, perhaps will be better to replace the
>>>>> variable with a literal?
>>>>>
>>>>> #define PMC_CLK_OUT_MUX_MASK    GENMASK(1, 0)
>>>> Maybe even:
>>>>
>>>> #define PMC_CLK_OUT_MUX_MASK(c)    GENMASK(c->shift + 1, c->shift)
>>
>> MUX Mask is used only here for PMC clock out and is same for all
>> clk_out mux so will use
>>
>> #define PMC_CLK_OUT_MUX_MASK    GENMASK(1, 0)
>>
>>> I want to point out that may be a separated gate/mux shifts is a fine
>>> variant, you should try and see whether another variants produce more
>>> concise result.
>>>
>>> [snip]
> 
> We can do mux_shift as gate_shift + 4 and that restricts this clk
> register only for clk1/2/3 as well and there are no other clocks in pmc
> anyway.
> 
> How about using bit shift define for CLK1, CLK2, and CLK3?
> 
> .mux_shift = PMC_CLK1_SRC_SEL_SHIFT,
> 
> .gate_shift = PMC_CLK1_FORCE_EN_SHIFT,
> 
> 

I think that just renaming ".gate_shift" -> ".force_en_shift" should be
good enough.