Re: [PATCH 6/6] PCI: tegra: Add support to enable slot regulators

[Vidya Sagar]

On 8/27/2019 9:17 PM, Andrew Murray wrote:

On Mon, Aug 26, 2019 at 01:01:43PM +0530, Vidya Sagar wrote:

Add support to get regulator information of 3.3V and 12V supplies of a PCIe
slot from the respective controller's device-tree node and enable those
supplies. This is required in platforms like p2972-0000 where the supplies
to x16 slot owned by C5 controller need to be enabled before attempting to
enumerate the devices.

Signed-off-by: Vidya Sagar <vid...@nvidia.com>
---
  drivers/pci/controller/dwc/pcie-tegra194.c | 65 ++++++++++++++++++++++
  1 file changed, 65 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c 
b/drivers/pci/controller/dwc/pcie-tegra194.c
index 8a27b25893c9..97de2151a738 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -278,6 +278,8 @@ struct tegra_pcie_dw {
        u32 aspm_l0s_enter_lat;

struct regulator *pex_ctl_supply;

+       struct regulator *slot_ctl_3v3;
+       struct regulator *slot_ctl_12v;

unsigned int phy_count;

        struct phy **phys;
@@ -1047,6 +1049,59 @@ static void tegra_pcie_downstream_dev_to_D0(struct 
tegra_pcie_dw *pcie)
        }
  }

+static void tegra_pcie_get_slot_regulators(struct tegra_pcie_dw *pcie)

+{
+       pcie->slot_ctl_3v3 = devm_regulator_get_optional(pcie->dev, "vpcie3v3");
+       if (IS_ERR(pcie->slot_ctl_3v3))
+               pcie->slot_ctl_3v3 = NULL;
+
+       pcie->slot_ctl_12v = devm_regulator_get_optional(pcie->dev, "vpcie12v");
+       if (IS_ERR(pcie->slot_ctl_12v))
+               pcie->slot_ctl_12v = NULL;

Do these need to take into consideration -EPROBE_DEFER?

Since these are devm_* APIs, isn't it taken care of automatically?

Thanks,

Andrew Murray

+}
+
+static int tegra_pcie_enable_slot_regulators(struct tegra_pcie_dw *pcie)
+{
+       int ret;
+
+       if (pcie->slot_ctl_3v3) {
+               ret = regulator_enable(pcie->slot_ctl_3v3);
+               if (ret < 0) {
+                       dev_err(pcie->dev,
+                               "Failed to enable 3V3 slot supply: %d\n", ret);
+                       return ret;
+               }
+       }
+
+       if (pcie->slot_ctl_12v) {
+               ret = regulator_enable(pcie->slot_ctl_12v);
+               if (ret < 0) {
+                       dev_err(pcie->dev,
+                               "Failed to enable 12V slot supply: %d\n", ret);
+                       if (pcie->slot_ctl_3v3)
+                               regulator_disable(pcie->slot_ctl_3v3);
+                       return ret;
+               }
+       }
+
+       /*
+        * According to PCI Express Card Electromechanical Specification
+        * Revision 1.1, Table-2.4, T_PVPERL (Power stable to PERST# inactive)
+        * should be a minimum of 100ms.
+        */
+       msleep(100);
+
+       return 0;
+}
+
+static void tegra_pcie_disable_slot_regulators(struct tegra_pcie_dw *pcie)
+{
+       if (pcie->slot_ctl_12v)
+               regulator_disable(pcie->slot_ctl_12v);
+       if (pcie->slot_ctl_3v3)
+               regulator_disable(pcie->slot_ctl_3v3);
+}
+
  static int tegra_pcie_config_controller(struct tegra_pcie_dw *pcie,
                                        bool en_hw_hot_rst)
  {
@@ -1060,6 +1115,10 @@ static int tegra_pcie_config_controller(struct 
tegra_pcie_dw *pcie,
                return ret;
        }

+ ret = tegra_pcie_enable_slot_regulators(pcie);

+       if (ret < 0)
+               goto fail_slot_reg_en;
+
        ret = regulator_enable(pcie->pex_ctl_supply);
        if (ret < 0) {
                dev_err(pcie->dev, "Failed to enable regulator: %d\n", ret);
@@ -1142,6 +1201,8 @@ static int tegra_pcie_config_controller(struct 
tegra_pcie_dw *pcie,
  fail_core_clk:
        regulator_disable(pcie->pex_ctl_supply);
  fail_reg_en:
+       tegra_pcie_disable_slot_regulators(pcie);
+fail_slot_reg_en:
        tegra_pcie_bpmp_set_ctrl_state(pcie, false);

return ret;

@@ -1174,6 +1235,8 @@ static int __deinit_controller(struct tegra_pcie_dw *pcie)
                return ret;
        }

+ tegra_pcie_disable_slot_regulators(pcie);

+
        ret = tegra_pcie_bpmp_set_ctrl_state(pcie, false);
        if (ret) {
                dev_err(pcie->dev, "Failed to disable controller %d: %d\n",
@@ -1372,6 +1435,8 @@ static int tegra_pcie_dw_probe(struct platform_device 
*pdev)
                return ret;
        }

+ tegra_pcie_get_slot_regulators(pcie);

+
        pcie->pex_ctl_supply = devm_regulator_get(dev, "vddio-pex-ctl");
        if (IS_ERR(pcie->pex_ctl_supply)) {
                dev_err(dev, "Failed to get regulator: %ld\n",
--
2.17.1