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Subject: Re: [PATCH v2 02/11] 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, tglx@linutronix.de, robh+dt@kernel.org,
        mark.rutland@arm.com
Cc:     allison@lohutok.net, pdeschrijver@nvidia.com, pgaikwad@nvidia.com,
        mturquette@baylibre.com, horms+renesas@verge.net.au,
        Jisheng.Zhang@synaptics.com, krzk@kernel.org, arnd@arndb.de,
        spujar@nvidia.com, josephl@nvidia.com, vidyas@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
References: <1574830773-14892-1-git-send-email-skomatineni@nvidia.com>
 <1574830773-14892-3-git-send-email-skomatineni@nvidia.com>
 <749de44c-ec59-3cab-c02e-7b8fcb1fb9f4@gmail.com>
 <3d1492a1-f2a5-2d56-5341-a28fcb73fe64@nvidia.com>
 <484cb1bb-4fb2-9e71-87be-2bd5bd5b2348@gmail.com>
 <e4ee58aa-c421-ea4b-a37b-574fc987c7c1@nvidia.com>
From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <e5da42b8-bf21-4b57-8ae6-37ce6ca4210c@gmail.com>
Date:   Tue, 3 Dec 2019 00:50:52 +0300
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02.12.2019 23:09, Sowjanya Komatineni пишет:
> 
> On 11/28/19 5:25 AM, Dmitry Osipenko wrote:
>> 28.11.2019 01:57, Sowjanya Komatineni пишет:
>>> On 11/27/19 7:14 AM, Dmitry Osipenko wrote:
>>>> 27.11.2019 07:59, Sowjanya Komatineni пишет:
>>>>> Tegra210 and prior Tegra PMC has clk_out_1, clk_out_2, clk_out_3 with
>>>>> mux and gate for each of these clocks.
>>>>>
>>>>> Currently these PMC clocks are registered by Tegra clock driver 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 clocks registration with PMC as a clock provider
>>>>> for these clocks. clk_ops callback implementations for these clocks
>>>>> uses tegra_pmc_readl and tegra_pmc_writel which supports PMC
>>>>> programming
>>>>> in secure mode and non-secure mode.
>>>>>
>>>>> Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
>>>>> ---
>>>>>    drivers/soc/tegra/pmc.c | 330
>>>>> ++++++++++++++++++++++++++++++++++++++++++++++++
>>>>>    1 file changed, 330 insertions(+)
>>>>>
>>>>> diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
>>>>> index ea0e11a09c12..a353f6d0a832 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 +160,91 @@
>>>>>    #define  TEGRA_SMC_PMC_READ    0xaa
>>>>>    #define  TEGRA_SMC_PMC_WRITE    0xbb
>>>>>    +struct pmc_clk_mux {
>>>>> +    struct clk_hw    hw;
>>>>> +    unsigned long    offs;
>>>>> +    u32        mask;
>>>>> +    u32        shift;
>>>>> +};
>>>>> +
>>>>> +#define to_pmc_clk_mux(_hw) container_of(_hw, struct pmc_clk_mux, hw)
>>>>> +
>>>>> +struct pmc_clk_gate {
>>>>> +    struct clk_hw    hw;
>>>>> +    unsigned long    offs;
>>>>> +    u32        shift;
>>>>> +};
>>>>> +
>>>>> +#define to_pmc_clk_gate(_hw) container_of(_hw, struct
>>>>> pmc_clk_gate, hw)
>>>>> +
>>>>> +struct pmc_clk_init_data {
>>>>> +    char *mux_name;
>>>>> +    char *gate_name;
>>>>> +    const char **parents;
>>>>> +    int num_parents;
>>>>> +    int mux_id;
>>>>> +    int gate_id;
>>>>> +    char *dev_name;
>>>>> +    u8 mux_shift;
>>>>> +    u8 gate_shift;
>>>>> +    u8 init_parent_index;
>>>>> +    int init_state;
>>>>> +};
>>>>> +
>>>>> +static const char *clk_out1_parents[] = { "clk_m", "clk_m_div2",
>>>>> +    "clk_m_div4", "extern1",
>>>>> +};
>>>>> +
>>>>> +static const char *clk_out2_parents[] = { "clk_m", "clk_m_div2",
>>>>> +    "clk_m_div4", "extern2",
>>>>> +};
>>>>> +
>>>>> +static const char *clk_out3_parents[] = { "clk_m", "clk_m_div2",
>>>>> +    "clk_m_div4", "extern3",
>>>>> +};
>>>>> +
>>>>> +static struct pmc_clk_init_data tegra_pmc_clks_data[] = {
>>>>> +    {
>>>>> +        .mux_name = "clk_out_1_mux",
>>>>> +        .gate_name = "clk_out_1",
>>>>> +        .parents = clk_out1_parents,
>>>>> +        .num_parents = ARRAY_SIZE(clk_out1_parents),
>>>>> +        .mux_id = TEGRA_PMC_CLK_OUT_1_MUX,
>>>>> +        .gate_id = TEGRA_PMC_CLK_OUT_1,
>>>>> +        .dev_name = "extern1",
>>>>> +        .mux_shift = 6,
>>>>> +        .gate_shift = 2,
>>>>> +        .init_parent_index = 3,
>>>>> +        .init_state = 1,
>>>>> +    },
>>>>> +    {
>>>>> +        .mux_name = "clk_out_2_mux",
>>>>> +        .gate_name = "clk_out_2",
>>>>> +        .parents = clk_out2_parents,
>>>>> +        .num_parents = ARRAY_SIZE(clk_out2_parents),
>>>>> +        .mux_id = TEGRA_PMC_CLK_OUT_2_MUX,
>>>>> +        .gate_id = TEGRA_PMC_CLK_OUT_2,
>>>>> +        .dev_name = "extern2",
>>>>> +        .mux_shift = 14,
>>>>> +        .gate_shift = 10,
>>>>> +        .init_parent_index = 0,
>>>>> +        .init_state = 0,
>>>>> +    },
>>>>> +    {
>>>>> +        .mux_name = "clk_out_3_mux",
>>>>> +        .gate_name = "clk_out_3",
>>>>> +        .parents = clk_out3_parents,
>>>>> +        .num_parents = ARRAY_SIZE(clk_out3_parents),
>>>>> +        .mux_id = TEGRA_PMC_CLK_OUT_3_MUX,
>>>>> +        .gate_id = TEGRA_PMC_CLK_OUT_3,
>>>>> +        .dev_name = "extern3",
>>>>> +        .mux_shift = 22,
>>>>> +        .gate_shift = 18,
>>>>> +        .init_parent_index = 0,
>>>>> +        .init_state = 0,
>>>>> +    },
>>>>> +};
>>>>> +
>>>>>    struct tegra_powergate {
>>>>>        struct generic_pm_domain genpd;
>>>>>        struct tegra_pmc *pmc;
>>>>> @@ -254,6 +344,9 @@ struct tegra_pmc_soc {
>>>>>         */
>>>>>        const struct tegra_wake_event *wake_events;
>>>>>        unsigned int num_wake_events;
>>>>> +
>>>>> +    struct pmc_clk_init_data *pmc_clks_data;
>>>>> +    unsigned int num_pmc_clks;
>>>>>    };
>>>>>      static const char * const tegra186_reset_sources[] = {
>>>>> @@ -2163,6 +2256,228 @@ 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_mux *mux = to_pmc_clk_mux(hw);
>>>>> +    int num_parents = clk_hw_get_num_parents(hw);
>>>>> +    u32 val;
>>>>> +
>>>>> +    val = tegra_pmc_readl(pmc, mux->offs) >> mux->shift;
>>>>> +    val &= mux->mask;
>>>>> +
>>>>> +    if (val >= num_parents)
>>>>> +        return -EINVAL;
>>>>> +
>>>>> +    return val;
>>>>> +}
>>>>> +
>>>>> +static int pmc_clk_mux_set_parent(struct clk_hw *hw, u8 index)
>>>>> +{
>>>>> +    struct pmc_clk_mux *mux = to_pmc_clk_mux(hw);
>>>>> +    u32 val;
>>>>> +
>>>>> +    val = tegra_pmc_readl(pmc, mux->offs);
>>>>> +    val &= ~(mux->mask << mux->shift);
>>>>> +    val |= index << mux->shift;
>>>>> +    tegra_pmc_writel(pmc, val, mux->offs);
>>>>> +    pmc_clk_fence_udelay(mux->offs);
>>>>> +
>>>>> +    return 0;
>>>>> +}
>>>>> +
>>>>> +static const struct clk_ops pmc_clk_mux_ops = {
>>>>> +    .get_parent = pmc_clk_mux_get_parent,
>>>>> +    .set_parent = pmc_clk_mux_set_parent,
>>>>> +    .determine_rate = __clk_mux_determine_rate,
>>>>> +};
>>>>> +
>>>>> +static struct clk *
>>>>> +tegra_pmc_clk_mux_register(const char *name, const char * const
>>>>> *parent_names,
>>>>> +               int num_parents, unsigned long flags,
>>>>> +               unsigned long offset, u32 shift, u32 mask)
>>>>> +{
>>>>> +    struct clk_init_data init;
>>>>> +    struct pmc_clk_mux *mux;
>>>>> +
>>>>> +    mux = kzalloc(sizeof(*mux), GFP_KERNEL);
>>>>> +    if (!mux)
>>>>> +        return ERR_PTR(-ENOMEM);
>>>>> +
>>>>> +    init.name = name;
>>>>> +    init.ops = &pmc_clk_mux_ops;
>>>>> +    init.parent_names = parent_names;
>>>>> +    init.num_parents = num_parents;
>>>>> +    init.flags = flags;
>>>>> +
>>>>> +    mux->hw.init = &init;
>>>>> +    mux->offs = offset;
>>>>> +    mux->mask = mask;
>>>>> +    mux->shift = shift;
>>>>> +
>>>>> +    return clk_register(NULL, &mux->hw);
>>>>> +}
>>>>> +
>>>>> +static int pmc_clk_is_enabled(struct clk_hw *hw)
>>>>> +{
>>>>> +    struct pmc_clk_gate *gate = to_pmc_clk_gate(hw);
>>>>> +
>>>>> +    return tegra_pmc_readl(pmc, gate->offs) & BIT(gate->shift) ? 1
>>>>> : 0;
>>>>> +}
>>>>> +
>>>>> +static void pmc_clk_set_state(struct clk_hw *hw, int state)
>>>>> +{
>>>>> +    struct pmc_clk_gate *gate = to_pmc_clk_gate(hw);
>>>>> +    u32 val;
>>>>> +
>>>>> +    val = tegra_pmc_readl(pmc, gate->offs);
>>>>> +    val = state ? (val | BIT(gate->shift)) : (val &
>>>>> ~BIT(gate->shift));
>>>>> +    tegra_pmc_writel(pmc, val, gate->offs);
>>>>> +    pmc_clk_fence_udelay(gate->offs);
>>>>> +}
>>>>> +
>>>>> +static int pmc_clk_enable(struct clk_hw *hw)
>>>>> +{
>>>>> +    pmc_clk_set_state(hw, 1);
>>>>> +
>>>>> +    return 0;
>>>>> +}
>>>>> +
>>>>> +static void pmc_clk_disable(struct clk_hw *hw)
>>>>> +{
>>>>> +    pmc_clk_set_state(hw, 0);
>>>>> +}
>>>>> +
>>>>> +static const struct clk_ops pmc_clk_gate_ops = {
>>>>> +    .is_enabled = pmc_clk_is_enabled,
>>>>> +    .enable = pmc_clk_enable,
>>>>> +    .disable = pmc_clk_disable,
>>>>> +};
>>>>> +
>>>>> +static struct clk *
>>>>> +tegra_pmc_clk_gate_register(const char *name, const char
>>>>> *parent_name,
>>>>> +                unsigned long flags, unsigned long offset,
>>>>> +                u32 shift)
>>>>> +{
>>>>> +    struct clk_init_data init;
>>>>> +    struct pmc_clk_gate *gate;
>>>>> +
>>>>> +    gate = kzalloc(sizeof(*gate), GFP_KERNEL);
>>>>> +    if (!gate)
>>>>> +        return ERR_PTR(-ENOMEM);
>>>>> +
>>>>> +    init.name = name;
>>>>> +    init.ops = &pmc_clk_gate_ops;
>>>>> +    init.parent_names = &parent_name;
>>>>> +    init.num_parents = 1;
>>>>> +    init.flags = flags;
>>>>> +
>>>>> +    gate->hw.init = &init;
>>>>> +    gate->offs = offset;
>>>>> +    gate->shift = shift;
>>>>> +
>>>>> +    return clk_register(NULL, &gate->hw);
>>>>> +}
>>>>> +
>>>>> +static void tegra_pmc_clock_register(struct tegra_pmc *pmc,
>>>>> +                     struct device_node *np)
>>>>> +{
>>>>> +    struct clk *clkmux, *clk, *parent;
>>>>> +    struct clk_onecell_data *clk_data;
>>>>> +    unsigned int num_clks;
>>>>> +    int i, ret;
>>>>> +
>>>>> +    /* each pmc clock output has a mux and a gate */
>>>>> +    num_clks = pmc->soc->num_pmc_clks * 2;
>>>>> +
>>>>> +    if (!num_clks)
>>>>> +        return;
>>>>> +
>>>>> +    clk_data = kmalloc(sizeof(*clk_data), GFP_KERNEL);
>>>>> +    if (!clk_data)
>>>>> +        return;
>>>>> +
>>>>> +    clk_data->clks = kcalloc(TEGRA_PMC_CLK_MAX,
>>>>> sizeof(*clk_data->clks),
>>>>> +                 GFP_KERNEL);
>>>>> +    if (!clk_data->clks)
>>>>> +        goto free_clkdata;
>>>>> +
>>>>> +    clk_data->clk_num = num_clks;
>>>>> +
>>>>> +    for (i = 0; i < pmc->soc->num_pmc_clks; i++) {
>>>>> +        struct pmc_clk_init_data *data;
>>>>> +
>>>>> +        data = pmc->soc->pmc_clks_data + i;
>>>>> +
>>>>> +        clkmux = tegra_pmc_clk_mux_register(data->mux_name,
>>>>> +                            data->parents,
>>>>> +                            data->num_parents,
>>>>> +                            CLK_SET_RATE_NO_REPARENT |
>>>>> +                            CLK_SET_RATE_PARENT,
>>>>> +                            PMC_CLK_OUT_CNTRL,
>>>>> +                            data->mux_shift, 3);
>>>>> +        if (IS_ERR(clkmux))
>>>>> +            goto free_clks;
>>>>> +
>>>>> +        clk_data->clks[data->mux_id] = clkmux;
>>>>> +
>>>>> +        clk = tegra_pmc_clk_gate_register(data->gate_name,
>>>>> +                          data->mux_name,
>>>>> +                          CLK_SET_RATE_PARENT,
>>>>> +                          PMC_CLK_OUT_CNTRL,
>>>>> +                          data->gate_shift);
>>>>> +        if (IS_ERR(clk))
>>>>> +            goto free_clks;
>>>>> +
>>>>> +        clk_data->clks[data->gate_id] = clk;
>>>>> +
>>>>> +        ret = clk_set_parent(clk, clkmux);
>>>>> +        if (ret < 0) {
>>>>> +            pr_err("failed to set parent of %s to %s\n",
>>>>> +                   __func__, __clk_get_name(clk),
>>>>> +                   __clk_get_name(clkmux));
>>>>> +        }
>>>>> +
>>>>> +        clk_register_clkdev(clk, data->dev_name, data->gate_name);
>>>>> +
>>>>> +        /* configure initial clock parent and state */
>>>>> +        parent = clk_get_sys(data->gate_name,
>>>>> +                     data->parents[data->init_parent_index]);

Couldn't the default parent be defined using "assigned clock" in a
device-tree? Please see "Assigned clock parents and rates" in the doc.

https://www.kernel.org/doc/Documentation/devicetree/bindings/clock/clock-bindings.txt

Then you could simply use of_clk_set_defaults(pmc->dev->of_node, true).

>>>>> +        if (!IS_ERR(parent)) {
>>>>> +            ret = clk_set_parent(clkmux, parent);
>>>>> +            if (ret < 0) {
>>>>> +                pr_err("failed to set parent of %s to %s\n",
>>>>> +                       __func__, __clk_get_name(clkmux),
>>>>> +                       __clk_get_name(parent));
>>>>> +                WARN_ON(1);
>>>>> +            }
>>>>> +        }
>>>>> +
>>>>> +        if (data->init_state) {
>>>>> +            if (clk_prepare_enable(clk)) {
>>>>> +                pr_err("failed to enable %s\n", __func__,
>>>>> +                       __clk_get_name(clk));
>>>>> +                WARN_ON(1);
>> Alternatively you could write it like this:
>>
>>     err = clk_prepare_enable(clk);
>>
>>     WARN_ON(err, "failed to enable %s: %d\n",
>>         __clk_get_name(clk), err);
>>
>>>> Should be a bit better to move the WARN_ON to the end of errors
>>>> handling
>>>> in order to catch all possible errors:
>>>>
>>>> @@ -2510,6 +2510,7 @@ static void tegra_pmc_clock_register(struct
>>>> tegra_pmc *pmc,
>>>>           return;
>>>>
>>>>    free_clks:
>>>> +       WARN_ON(1);
>>>>           kfree(clk_data->clks);
>>>>    free_clkdata:
>>>>           kfree(clk_data);
>>> Reason I had WARN_ON right during clk_set_parent failure is to have the
>>> loop continue for subsequence pmc clocks registration instead of
>>> terminating all pmc clocks registration.
>> Ah, okay. Nevertheless this WARN_ON in the end shouldn't be the least
>> (IMO).
> Hi Dmitry, Just want to be clear on the above comment. Are you
> suggesting to add additional WARN_ON at the end?

Yes, it was my suggestion.

> Thought WARN_ON right during corresponding clock failure with warn
> message showing clock names will be clear and also other clocks still
> should be registered.
> 
> To add additional WARN_ON at the end need to track status of each clock
> and use that to as warn condition.

You could add a warning/error message to every point of failure.

Primarily, it is important not to miss a error. Secondarily, it is
important to make diagnostic message meaningful.

Realistically, I doubt that this chunk of code will ever fail once it is
known to work well. So it will be nice to have a more detailed
diagnostics (just in a case), but it shouldn't be a must.