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Date:   Wed, 18 Dec 2019 16:41:04 -0800
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     Dmitry Osipenko <digetx@...il.com>, <thierry.reding@...il.com>,
        <jonathanh@...dia.com>, <mperttunen@...dia.com>,
        <gregkh@...uxfoundation.org>, <sboyd@...nel.org>,
        <robh+dt@...nel.org>, <mark.rutland@....com>
CC:     <pdeschrijver@...dia.com>, <pgaikwad@...dia.com>,
        <spujar@...dia.com>, <josephl@...dia.com>,
        <daniel.lezcano@...aro.org>, <mmaddireddy@...dia.com>,
        <markz@...dia.com>, <devicetree@...r.kernel.org>,
        <linux-clk@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 06/19] soc: tegra: Add Tegra PMC clock registrations
 into PMC driver


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@...dia.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);
>>>> +
>>>> +	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]

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