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Subject: Re: [PATCH v3 03/15] 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
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        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, lgirdwood@gmail.com,
        broonie@kernel.org, perex@perex.cz, tiwai@suse.com,
        alexios.zavras@intel.com, alsa-devel@alsa-project.org
References: <1575600535-26877-1-git-send-email-skomatineni@nvidia.com>
 <1575600535-26877-4-git-send-email-skomatineni@nvidia.com>
From:   Dmitry Osipenko <digetx@gmail.com>
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Date:   Sat, 7 Dec 2019 17:28:17 +0300
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06.12.2019 05:48, 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 | 305 ++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 305 insertions(+)
> 
> diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
> index ea0e11a09c12..b8f6eb0ed8aa 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 +160,83 @@
>  #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;
> +};
> +
> +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 const 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,
> +	},
> +	{
> +		.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,
> +	},
> +	{
> +		.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,
> +	},
> +};
> +
>  struct tegra_powergate {
>  	struct generic_pm_domain genpd;
>  	struct tegra_pmc *pmc;
> @@ -254,6 +336,9 @@ 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 +2248,211 @@ 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;

How this could ever happen?

Why are you returning negative value for u8? It doesn't different from
returning val >= num_parents.

> +	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,
> +};

What's the benefit of separating GATE from the MUX?

I think it could be a single clock.

> +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;
> +	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 = TEGRA_PMC_CLK_MAX;
> +
> +	for (i = 0; i < TEGRA_PMC_CLK_MAX; i++)
> +		clk_data->clks[i] = ERR_PTR(-ENOENT);
> +
> +	for (i = 0; i < pmc->soc->num_pmc_clks; i++) {
> +		const 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: %d\n",
> +			       __clk_get_name(clk),
> +			       __clk_get_name(clkmux), ret);
> +		}

is this really needed? GATE clock has a single parent, the MUX.