Re: [PATCH v2 1/2] PCI: qcom: Add system PM support

[Matthias Kaehlcke]

On Wed, Jun 29, 2022 at 03:03:33PM +0530, Krishna chaitanya chundru wrote:
> Add suspend and resume pm callbacks.
> 
> When system suspends, and if the link is in L1ss, disable the clocks
> so that system enters into low power state to save the maximum power.
> And when the system resumes, enable the clocks back if they are
> disabled in the suspend path.
> 
> Changes since v1:
> 	- Fixed compilation errors.
> 
> Signed-off-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>
> ---
>  drivers/pci/controller/dwc/pcie-qcom.c | 81 ++++++++++++++++++++++++++++++++++
>  1 file changed, 81 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index 6ab9089..8e9ef37 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -41,6 +41,9 @@
>  #define L23_CLK_RMV_DIS				BIT(2)
>  #define L1_CLK_RMV_DIS				BIT(1)
>  
> +#define PCIE20_PARF_PM_STTS                     0x24
> +#define PCIE20_PARF_PM_STTS_LINKST_IN_L1SUB    BIT(8)
> +
>  #define PCIE20_PARF_PHY_CTRL			0x40
>  #define PHY_CTRL_PHY_TX0_TERM_OFFSET_MASK	GENMASK(20, 16)
>  #define PHY_CTRL_PHY_TX0_TERM_OFFSET(x)		((x) << 16)
> @@ -190,6 +193,8 @@ struct qcom_pcie_ops {
>  	void (*post_deinit)(struct qcom_pcie *pcie);
>  	void (*ltssm_enable)(struct qcom_pcie *pcie);
>  	int (*config_sid)(struct qcom_pcie *pcie);
> +	int (*enable_clks)(struct qcom_pcie *pcie);
> +	int (*disable_clks)(struct qcom_pcie *pcie);
>  };
>  
>  struct qcom_pcie_cfg {
> @@ -199,6 +204,7 @@ struct qcom_pcie_cfg {
>  	unsigned int has_ddrss_sf_tbu_clk:1;
>  	unsigned int has_aggre0_clk:1;
>  	unsigned int has_aggre1_clk:1;
> +	unsigned int support_pm_ops:1;

nit: s/support_pm_ops/supports_system_suspend/ ?

It's not really the ops that are supported, but system suspend. 'supports'
(with an 's' at the end) to specify a characteristic of the
driver/controller (similar to the 'has_<something>'s above), rather than
an imperative of what the driver should do.

In any case, it's just a nit :)

>  };
>  
>  struct qcom_pcie {
> @@ -209,6 +215,7 @@ struct qcom_pcie {
>  	struct phy *phy;
>  	struct gpio_desc *reset;
>  	const struct qcom_pcie_cfg *cfg;
> +	unsigned int is_suspended:1;
>  };
>  
>  #define to_qcom_pcie(x)		dev_get_drvdata((x)->dev)
> @@ -1308,6 +1315,23 @@ static void qcom_pcie_post_deinit_2_7_0(struct qcom_pcie *pcie)
>  	clk_disable_unprepare(res->pipe_clk);
>  }
>  
> +static int qcom_pcie_enable_clks_2_7_0(struct qcom_pcie *pcie)
> +{
> +	struct qcom_pcie_resources_2_7_0 *res = &pcie->res.v2_7_0;
> +
> +	return clk_bulk_prepare_enable(res->num_clks, res->clks);
> +}
> +
> +static int qcom_pcie_disable_clks_2_7_0(struct qcom_pcie *pcie)
> +{
> +	struct qcom_pcie_resources_2_7_0 *res = &pcie->res.v2_7_0;
> +
> +	clk_bulk_disable_unprepare(res->num_clks, res->clks);
> +
> +	return 0;
> +}
> +
> +

nit: delete one empty line

>  static int qcom_pcie_link_up(struct dw_pcie *pci)
>  {
>  	u16 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> @@ -1485,6 +1509,8 @@ static const struct qcom_pcie_ops ops_2_7_0 = {
>  	.ltssm_enable = qcom_pcie_2_3_2_ltssm_enable,
>  	.post_init = qcom_pcie_post_init_2_7_0,
>  	.post_deinit = qcom_pcie_post_deinit_2_7_0,
> +	.enable_clks = qcom_pcie_enable_clks_2_7_0,
> +	.disable_clks = qcom_pcie_disable_clks_2_7_0,
>  };
>  
>  /* Qcom IP rev.: 1.9.0 */
> @@ -1548,6 +1574,7 @@ static const struct qcom_pcie_cfg sc7280_cfg = {
>  	.ops = &ops_1_9_0,
>  	.has_tbu_clk = true,
>  	.pipe_clk_need_muxing = true,
> +	.support_pm_ops = true,
>  };
>  
>  static const struct dw_pcie_ops dw_pcie_ops = {
> @@ -1591,6 +1618,8 @@ static int qcom_pcie_probe(struct platform_device *pdev)
>  
>  	pcie->cfg = pcie_cfg;
>  
> +	pcie->is_suspended = false;

not strictly necessary because of kzalloc, but does no harm either.

> +
>  	pcie->reset = devm_gpiod_get_optional(dev, "perst", GPIOD_OUT_HIGH);
>  	if (IS_ERR(pcie->reset)) {
>  		ret = PTR_ERR(pcie->reset);
> @@ -1645,6 +1674,57 @@ static int qcom_pcie_probe(struct platform_device *pdev)
>  	return ret;
>  }
>  
> +static int __maybe_unused qcom_pcie_pm_suspend(struct device *dev)
> +{
> +	struct qcom_pcie *pcie = dev_get_drvdata(dev);
> +	u32 val;
> +
> +	if (!pcie->cfg->support_pm_ops)
> +		return 0;
> +
> +	/* if the link is not in l1ss don't turn off clocks */
> +	val = readl(pcie->parf + PCIE20_PARF_PM_STTS);
> +	if (!(val & PCIE20_PARF_PM_STTS_LINKST_IN_L1SUB)) {
> +		dev_err(dev, "Link is not in L1ss\n");

If this is an error, should the function return an error? Otherwise maybe it
should be a warning.

> +		return 0;
> +	}
> +
> +	if (pcie->cfg->ops->disable_clks)
> +		pcie->cfg->ops->disable_clks(pcie);
> +
> +	if (pcie->cfg->ops->post_deinit)
> +		pcie->cfg->ops->post_deinit(pcie);
> +
> +	pcie->is_suspended = true;
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused qcom_pcie_pm_resume(struct device *dev)
> +{
> +	struct qcom_pcie *pcie = dev_get_drvdata(dev);
> +
> +	if (!pcie->cfg->support_pm_ops)
> +		return 0;
> +
> +	if (!pcie->is_suspended)
> +		return 0;
> +
> +	if (pcie->cfg->ops->enable_clks)
> +		pcie->cfg->ops->enable_clks(pcie);
> +
> +	if (pcie->cfg->ops->post_init)
> +		pcie->cfg->ops->post_init(pcie);
> +
> +	pcie->is_suspended = false;
> +
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops qcom_pcie_pm_ops = {
> +	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(qcom_pcie_pm_suspend, qcom_pcie_pm_resume)
> +};
> +
>  static const struct of_device_id qcom_pcie_match[] = {
>  	{ .compatible = "qcom,pcie-apq8084", .data = &apq8084_cfg },
>  	{ .compatible = "qcom,pcie-ipq8064", .data = &ipq8064_cfg },
> @@ -1679,6 +1759,7 @@ static struct platform_driver qcom_pcie_driver = {
>  	.probe = qcom_pcie_probe,
>  	.driver = {
>  		.name = "qcom-pcie",
> +		.pm = &qcom_pcie_pm_ops,
>  		.suppress_bind_attrs = true,
>  		.of_match_table = qcom_pcie_match,
>  	},
> -- 
> 2.7.4
>